A study of factors that influence growth performance and carcass and meat quality of iberian pigs reared under intensive management systems : Estudio de los factores que influyen sobre la productividad y la calidad de la canal y la carne de cerdo Ibérico

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(1)UNIVERSIDAD POLITÉCNICA DE MADRID ESCUELA TÉCNICA SUPERIOR DE INGENIEROS AGRÓNOMOS. A STUDY OF FACTORS THAT INFLUENCE GROWTH PERFORMANCE AND CARCASS AND MEAT QUALITY OF IBERIAN PIGS REARED UNDER INTENSIVE MANAGEMENT SYSTEMS. Estudio de los factores que influyen sobre la productividad y la calidad de la canal y la carne de cerdo Ibérico en intensivo. TESIS DOCTORAL. Martina Pérez Serrano Ingeniero Agrónomo. 2008.

(2) DEPARTAMENTO DE PRODUCCIÓN ANIMAL ESCUELA TÉCNICA SUPERIOR DE INGENIEROS AGRÓNOMOS. A STUDY OF FACTORS THAT INFLUENCE GROWTH PERFORMANCE AND CARCASS AND MEAT QUALITY OF IBERIAN PIGS REARED UNDER INTENSIVE MANAGEMENT SYSTEMS. Martina Pérez Serrano Ingeniero Agrónomo. Directores de la tesis. Gonzalo González Mateos. Rosa Lázaro García. Dr. Ingeniero Agrónomo. Dr. Ingeniero Agrónomo 2008.

(3) Queda prohibido llorar sin aprender. Queda prohibido no sonreír a los problemas, no luchar por lo que quieres, abandonarlo todo por miedo y no convertir en realidad tus sueños. Si te vas a calentar, que sea al sol. Si vas a engañar, que sea a tu estómago. Si vas a llorar, que sea de alegría. Si vas a mentir, que sea la edad. Si vas a robar, que sea un beso. Si vas a perder, que se pierda el miedo. Y si existe hambre, que sea de amor. Y si es para ser feliz, que sea todo el tiempo. Pablo Neruda. A mi familia y a Diego.

(4) AGRADECIMIENTOS A mis padres por haber hecho de mi casa un hogar, de mi familia mi pilar y de mi lo que soy. Por vuestro apoyo incondicional y por el esfuerzo que habéis hecho por darnos siempre lo mejor. Sois los mejores padres que se puede tener. Gracias papá. Gracias mamá. A mis hermanos por ser mi apoyo y mi respaldo. A Candi, por ser mi referente en la vida en tantos aspectos, por estar siempre pendiente de todos, por haberme guiado siempre por el buen camino y por ayudarme tanto. A Javi, por inculcarme el amor a los animales, siempre recordaré mi infancia a tu lado. A Zequi por su infinita paciencia, porque al ser el que más cerca estás, te ha tocado aguantar los momentos difíciles. A Marga por dejarme formar parte de su vida tantas y tantas horas. Por estar siempre ahí, por dar a tu casa y a la mía la alegría y las ganas de vivir que desprendes y por ser la hermana que nunca tuve. Gracias por compartir tu vida con nosotros. A Rosa por darnos a esos dos enanos que le quitan las penas a cualquiera. A mis niños por ser la luz de mis días. Gracias Sara por hacerme ver proyectada en ti en tantas cosas. Siempre serás mi niña del alma, mi ojo derecho. Gracias Alba por ser capaz de convertir cualquier lágrima en una sonrisa y por darme los mejores regalos que he recibido; tus abrazos. La vida es mucho más fácil desde que tú estás con nosotros. Gracias Fernando por ser capaz de hacerme regresar a la infancia con tu vida llena de locura. Gracias Alejandro, el bebé de la casa, por representar la inocencia en el mundo en que vivimos. Gracias por tus sonrisas enano. A Diego porque sin ti ni este sueño ni tantos otros hubiesen sido posibles. Gracias por ser como eres y por vivir como vives. Por ser un ejemplo de superación constante, por tu manera de relativizar los problemas y por tener siempre una sonrisa. Compartir la vida contigo es un aprendizaje continuo. A tu lado no hay problemas, todo tiene solución. Eres la persona más fuerte, más valiente y más alegre que he conocido. Gracias por haberlo dado todo por buscar tu sitio en la vida y gracias a Dios.

(5) por convertir tu Norte en mi Sur y haberte puesto en mi camino. En conclusión, eres el mejor resultado de esta Tesis, sin discusión. A mi nueva familia en Colombia y, en especial a Rodri. Sois los mejores humoristas con los que uno se puede encontrar. A la abuela por ser una fuente de aliento y de halago. A Rafa por iniciarme en el trabajo de granja y en la vida en el campo. A mis amigos por entender la cantidad de tiempo que les he robado por dedicarme a estos menesteres. Gracias a todos por vuestra gran amistad y por los buenos momentos. A Gonzalo y a Rosa por darme el privilegio de trabajar con vosotros, por enseñarme y confiar en mí. Gracias por todo lo que aprendido en la Tesis Doctoral que he hecho de la vida. Seguro que me servirá siempre. A la Comunidad de Madrid y a la U.P. Madrid por contratarme. A Alfonso Fuentetaja, Marcos Nieto, Isabel, Laura, Marta y David de Copese, S.A. por su constante ayuda y por los buenos momentos que hemos compartido. Ha sido un placer trabajar con vosotros. Al personal de la Estación Tecnológica de la Carne por su colaboración y por enseñarme a analizar las muestras de carne y grasa. A Clemente López-Bote y a Argimiro Daza por resolverme tantas dudas. A Carlos de Blas, Rosa Carabaño y Javier García por sus consejos estadísticos. A David Menoyo, José Sánchez, Angel González, Beatriz Babé, Mohamed Frikha, Hosam Safaa, Javier Corchero, Gladistone Brumano y Nuria Parera por hacer la recta final mucho más fácil y por vuestra ayuda tanto en la nave como fuera de ella. A José Daniel Rodríguez por su ayuda en los análisis de laboratorio. A Javier Rodríguez y a Yolanda Alegre pos su simpatía y disponibilidad para ayudarme en lo que hizo falta. A todos los que alguna vez tuvieron una sonrisa A todos, muchas gracias.

(6) INDEX.

(7) Index INDEX OF CONTENTS. Page 14. CHAPTER 1: LITERATURE REVIEW AND OBJECTIVES CHAPTER 2: EFFECT OF GENDER AND CASTRATION OF FEMALES AND SLAUGHTER WEIGHT ON PERFORMANCE AND CARCASS AND MEAT QUALITY OF IBERIAN PIGS REARED. 98. UNDER INTENSIVE MANAGEMENT SYSTEMS (TRIAL 1) CHAPTER 3: INFLUENCE OF FEED RESTRICTION AND GENDER ON GROWTH PERFORMANCE AND CARCASS AND MEAT. 126. QUALITY OF IBERIAN PIGS REARED INDOORS (TRIAL 2) CHAPTER 4: EFFECT OF CASTRATION ON PRODUCTIVE PERFORMANCE, QUALITY. OF. CARCASS IBERIAN. CHARACTERISTICS. PIG. FEMALES. AND. REARED. MEAT UNDER. INTENSIVE MANAGEMENT SYSTEMS (TRIAL 3). 155. CHAPTER 5: INFLUENCE OF SEX AND TERMINAL SIRE LINE ON PERFORMANCE AND CARCASS AND MEAT QUALITY OF IBERIAN PIGS REARED UNDER INTENSIVE MANAGEMENT 183. SYSTEMS (TRIAL 4) CHAPTER 6: GENERAL DISCUSSION AND CONCLUSIONS. 213. ANNEX I: RESUMEN EN ESPAÑOL. 235. II.

(8) Index INDEX Page Resumen. 1. Abstract. 8. CHAPTER 1: LITERATURE REVIEW AND OBJECTIVES. 14. 1. Literature review. 15. 1.1. Introduction. 15. 1.2. Legislation for Iberian pig products. 16. 1.3. Productivity of Iberian pigs. 18. 1.4. Measures of carcass quality. 22. 1.4.1. Carcass yield. 22. 1.4.2. Carcass fat. 26. 1.4.3. Carcass length. 28. 1.4.4. Perimeter and length of hams. 29. 1.4.5. Perimeter and length of tarsus. 30. 1.4.6. pH. 31. 1.4.7. Shrink loss. 34. 1.4.8. Primal cuts. 34. 1.4.9. Weight loss of the ham during ripening. 39 40. 1.5. Measures of meat quality 1.5.1. Chemical composition. 41. 1.5.2. Meat colour. 46 52. 1.6. Measures of fat quality 1.7. Factors that influence productivity, carcass and meat quality and fatty acid profile of subcutaneous fat. 61. 1.7.1. Gender and castration. 61. 1.7.2. Slaughter weight. 67. 1.7.3. Feed restriction. 74. 1.7.4. Sire line. 82. 2. Objectives. 87. 3. References. 88. III.

(9) Index CHAPTER 2: EFFECT OF GENDER AND CASTRATION OF FEMALES AND SLAUGHTER WEIGHT ON PERFORMANCE AND CARCASS AND MEAT QUALITY OF IBERIAN PIGS REARED UNDER INTENSIVE MANAGEMENT SYSTEMS (TRIAL 1) 1. Introduction 2. Material and methods. 98 99 100. 2.1. Husbandry and diets. 100. 2.2. Productive performance traits. 103. 2.3. Carcass traits. 103. 2.4. Meat traits and fatty acid profile of subcutaneous fat. 105. 2.5. Statistical analyses. 106. 3. Results. 107. 3.1. Productive performance traits. 107. 3.2. Carcass traits. 110. 3.3. Meat traits and fatty acid profile of subcutaneous fat. 112. 4. Discussion. 115. 4.1. Productive performance traits. 115. 4.2. Carcass traits. 116. 4.3. Meat traits and fatty acid profile of subcutaneous fat. 118. 5. Conclusions. 120. 6. References. 120. CHAPTER 3: INFLUENCE OF FEED RESTRICTION AND GENDER ON GROWTH PERFORMANCE AND CARCASS AND MEAT QUALITY OF IBERIAN PIGS REARED INDOORS (TRIAL 2). 126. 1. Introduction. 127. 2. Materials and methods. 128. 2.1. Pig husbandry and growth performance. 128. 2.2. Handling, slaughtering and carcass traits. 131. 2.3. Meat quality traits and fatty acid profile of subcutaneous fat. 133. 2.4. Statistical analyses. 134. 3. Results. 135. 3.1. Growth performance. 135. 3.2. Carcass traits. 138. 3.3. Meat quality traits and fatty acid profile of subcutaneous fat. 141. 4. Discussion. 143. IV.

(10) Index 4.1. Growth performance. 143. 4.2. Carcass traits. 144. 4.3. Meat quality traits and fatty acid profile of subcutaneous fat. 147. 5. Conclusions. 148. 6. References. 148. CHAPTER 4: EFFECT OF CASTRATION ON PRODUCTIVE PERFORMANCE, QUALITY. OF. CARCASS IBERIAN. CHARACTERISTICS. PIG. FEMALES. AND. REARED. MEAT UNDER. INTENSIVE MANAGEMENT SYSTEMS (TRIAL 3). 155. 1. Introduction. 156. 2. Material and methods. 157. 2.1. Pig husbandry and growth performance. 157. 2.2. Handling, slaughtering and carcass traits. 160. 2.3. Meat quality traits and fatty acid profile of subcutaneous fat. 161. 2.4. Statistical analyses. 163. 3. Results. 164. 3.1. Growth performance. 164. 3.2. Carcass traits. 168. 3.3. Meat quality traits and fatty acid profile of subcutaneous fat. 170. 4. Discussion. 173. 4.1. Growth performance. 173. 4.2. Carcass traits. 173. 4.3. Meat quality traits and fatty acid profile of subcutaneous fat. 175. 5. Conclusions. 177. 6. References. 177. CHAPTER 5: INFLUENCE OF SEX AND TERMINAL SIRE LINE ON PERFORMANCE AND CARCASS AND MEAT QUALITY OF IBERIAN PIGS REARED UNDER INTENSIVE PRODUCTION 183. SYSTEMS (TRIAL 4) 1. Introduction. 184. 2. Material and methods. 185. 2.1. Husbandry and diets. 185. 2.2. Productive performance traits. 186. 2.3. Carcass traits. 187. V.

(11) Index 2.4. Meat traits and fatty acid profile of subcutaneous fat. 189. 2.5. Statistical analyses. 190. 3. Results. 191. 3.1. Productive performance traits. 191. 3.2. Carcass traits. 194. 3.3. Meat traits and fatty acid profile of subcutaneous fat. 198. 4. Discussion. 200. 4.1. Productive performance traits. 200. 4.2. Carcass traits. 201. 4.3. Meat traits and fatty acid profile of subcutaneous fat. 204. 5. Conclusions. 206. 6. References. 206. CHAPTER 6: GENERAL DISCUSSION AND CONCLUSIONS 1. General discussion. 213 214. 1.1. Influence of gender and castration on productivity, carcass and meat quality and fatty acid profile of subcutaneous fat. 214. 1.1.1. Productivity. 214. 1.1.2. Carcass quality. 214. 1.1.3. Meat quality. 217. 1.1.4. Fatty acid profile of subcutaneous fat. 218. 1.2. Influence of slaughter weight on productivity and carcass and 219. meat quality 1.2.1. Productivity. 219. 1.2.2. Carcass quality. 220. 1.2.3. Meat quality. 221. 1.3. Influence of feed restriction on productivity, carcass and meat quality and fatty acid profile of subcutaneous fat. 221. 1.3.1. Productivity. 221. 1.3.2. Carcass quality. 222. 1.3.3. Meat quality. 223. 1.3.4. Fatty acid profile of subcutaneous fat. 224. 1.4. Influence of sire line on productivity, carcass and meat quality 224. and fatty acid profile of subcutaneous fat 1.4.1. Productivity. 224. 1.4.2. Carcass quality. 225. VI.

(12) Index 1.4.3. Meat quality. 226. 1.4.4. Fatty acid profile of subcutaneous fat. 227. 2. Conclusions. 227. 3. References. 228 235. ANNEX I: RESUMEN EN ESPAÑOL 1. Revisión bibliográfica. 237. 1.1. Introducción. 237. 1.2. Norma de calidad para productos Ibéricos. 238. 1.3. Factores que influyen sobre la productividad y la calidad de la canal y la carne en cruces de cerdo Ibérico x Duroc producidos bajo 241. sistemas intensivos 2. Objetivo de la Tesis Doctoral. 244. 3. Material y métodos. 245. 3.1. Animales y manejo. 245. 3.2. Diseño experimental. 245. 3.3. Controles. 248. 3.3.1. Productividad. 248. 3.3.2. Calidad de la canal. 249. 3.3.3. Calidad de la carne. 253. 3.3.4. Perfil de ácidos grasos de la grasa subcutánea. 253 254. 3.4. Análisis estadísticos 4. Resultados. 256. 4.1. Influencia del sexo y la castración de las hembras sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea (Ensayos 1, 2, 3 y 4). 256. 4.2. Influencia del peso al sacrificio sobre la productividad y la 260. calidad de la canal y la carne (Ensayo 1) 4.3. Influencia de la restricción del consumo de pienso sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea (Ensayo 2). 260. 4.4. Influencia de la línea paterna sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea (Ensayo 4). 262. 5. Discusión general. 264. VII.

(13) Index 5.1. Influencia del sexo y la castración de las hembras sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea (Ensayos 1, 2, 3 y 4). 264. 5.1.1. Productividad. 264. 5.1.2. Calidad de la canal. 264. 5.1.3. Calidad de la carne. 267. 5.1.4. Perfil de ácidos grasos de la grasa subcutánea. 269. 5.2. Influencia del peso al sacrificio sobre la productividad y la calidad de la canal y de la carne (Ensayo 1). 270. 5.2.1. Productividad. 270. 5.2.2. Calidad de la canal. 270. 5.2.3. Calidad de la carne. 272. 5.3. Influencia de la restricción del consumo de pienso sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea (Ensayo 2). 272. 5.3.1. Productividad. 272. 5.3.2. Calidad de la canal. 274. 5.3.3. Calidad de la carne. 275. 5.3.4. Perfil de ácidos grasos de la grasa subcutánea. 275. 5.4. Influencia de la línea paterna sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa 276. subcutánea (Ensayo 4) 5.4.1. Productividad. 276. 5.4.2. Calidad de la canal. 276. 5.4.3. Calidad de la carne. 278. 5.4.4. Perfil de ácidos grasos de la grasa subcutánea. 279. 6. Conclusiones generales y recomendaciones de la Tesis Doctoral. 279. 7. Referencias. 280. VIII.

(14) ABBREVIATION KEYS.

(15) Abbreviation keys. ABBREVIATION KEYS ºC: degree Celsius; grado centígrado. *: P<0.05. **: P<0.01. ***: P<0.001. %: percentage; porcentaje. ∑: sum; sumatorio. †: tendency (P<0.10); tendencia (P<0,10). A: ampere; amperio. a*: redness; tendencia al rojo. ADFI: average daily feed intake. ADG: average daily gain. AL: ad libitum. b*: yellowness; tendencia al amarillo. BF: backfat. BW: body weight. c*: chroma; croma. C12:0: lauric acid; ácido laúrico. C14:0: miristic acid; ácido mirístico. C16:0: palmitic acid; ácido palmítico. C16:1: palmitoleic acid; ácido palmitoleico. C17:0: margaric acid; ácido margárico. C17:1: heptadecenoic acid; ácido heptadecanoico. C18:0: stearic acid; ácido esteárico. C18:1: oleic acid; ácido oleico.. X.

(16) Abbreviation keys C18:2: linoleic acid; ácido linoleico. C18:3: linolenic acid; ácido linolénico. C20:0: acid araquidic; ácido araquídico. C20:1. gadoleic acid; ácido gadoleico. CDC28 + FR83: pigs fed on concentrates in confinement for 28 initial d and in free-range with acorns and grass for 83 d. CDC65 + FR46: pigs fed on concentrates in confinement for 65 initial d and in free-range with acorns and grass for 46 d. CDC111: pigs fed on concentrates in confinement for 111 d CF: castrated female. CM: castrated male. cm: centimeter; centímetro. CMD: consumo medio diario. CP: crude protein. d: day; día. DD: Danish Duroc; Duroc Danés. DE: Duroc Estándar Degesa. DFD: dark, firm and dry meat; carne oscura, firme y seca. DMb: purplish-red deoxymyoglobin. DU: Duroc. et al.: and collaborators; y colaboradores. FA: fatty acid. FCR: feed conversion ratio. FR: feed restriction. FR111: pigs fed, under free-range conditions, with acorns and grass for 111 d.. XI.

(17) Abbreviation keys g: gram; gramo. G:F: gain:feed. GIM: grasa intramuscular. GM: Gluteus medius. GMD: ganancia media diaria. h: hour; hora. Hº: hue angle; ángulo hue. ha: hectare; hectárea. HE: hembra entera. HC: hembra castrada. HR: humedad relativa. IB: Iberian; Ibérico. IC: índice de conversión. IF: intact female. IM: intact male. IMF: intramuscular fat. kcal: kilocalorie; kilocaloría. kg: kilogram; kilogramo. km: kilometer; kilómetro. L*: lightness; luminosidad. Ld: Landrace. LL: Longissimus lumborum. LM: Longissimus dorsi. LW: Large White. m: meter; metro.. XII.

(18) Abbreviation keys m2: meter square; metro cuadrado. m.: muscle; músculo. m. BF: Bíceps femoris. m. CF: Cuadriceps femoris. MC: macho castrado. MF: muscular fat. mg: miligram; miligramo. min: minute; minuto. MJ: megajoule; megajulio. mL: mililiter; mililitro. mm: milimeter; milímetro. mo: month. MMb: brown metmyoglobin. MS: Masseter. MUFA: monounsaturated fatty acid. N: nitrogen; nitrógeno. n: replicates per treatment; réplicas por tratamiento. nm: nanometer; nanometro. no.: number; número. NS: not significant difference (P>0.10); diferencia no significativa (P>0,10). OMb: bright red oxymyoglobin. P: probability; probabilidad. P2: backfat depth between the third and fourth last ribs on the midline of the carcass. pH2: pH at 2 h post mortem; pH a 2 h post mortem. pH24: pH at 24 h post mortem; pH a 24 h post mortem.. XIII.

(19) Abbreviation keys pHu: ultimate pH or pH at 24 h post mortem; pH último o pH a 24 h post mortem. Pi: Pietrain. PM: Psoas major. PSE: pale, soft and exudative meat; carne pálida, suave y exudativa. PUFA: polyunsaturated fatty acid. PV: peso vivo. r: Pearson correlation coefficient; coeficiente de correlación de Pearson. RH: relative humidity. RIB: Retinto Iberian; Retinto Ibérico. s: second; segundo. SAS: Statistical Analysis Systems. SD: Spanish Duroc. SEM: standard error of the mean. SFA: saturated fatty acid. SM: Semimembranosus. SV: Serratus ventralis. SW: slaughter weight. TC: Tibialis cranialis. UI: unsaturation index. V: volt; voltio. vs.: versus.. XIV.

(20) RESUMEN.

(21) Resumen RESUMEN. El objetivo general de esta Tesis Doctoral fue estudiar la influencia de los fatores que influyen sobre la productividad y la calidad de la canal y la carne de cerdos Ibéricos (IB) criados en sistemas intensivos. Los factores estudiados fueron el sexo y la castración de las hembras, el peso al sacrificio, la restricción de la alimentación y la línea paterna. Se llevaron a cabo cuatro ensayos.. En el primer ensayo se utilizaron 360 cerdos cruce de hembra IB (Retinta) con macho Duroc (Degesa) para estudiar la influencia del sexo y la castración de las hembras (hembra entera, HE vs. hembra castrada, HC vs. macho castrado, MC) y el peso al sacrificio (145 vs. 156 kg de peso vivo, PV) sobre la productividad y la calidad de la canal y la carne. Asimismo, se estudió la influencia del sexo y la castración sobre el perfil en ácidos grasos de la grasa subcutánea en cerdos sacrificados a 145 kg PV. Los cerdos que se sacrificaron con 145 kg PV (251 d de edad) iniciaron la prueba con 20 kg PV (80 d de edad) y los cerdos que se sacrificaron con 156 kg PV (268 d de edad) iniciaron la prueba con 30 kg PV (97 d de edad). Las muestras de carne se tomaron del m. Longissimus dorsi a la altura de la última costilla y las de grasa subcutánea a la altura de la inserción del rabo. Se llevó a cabo un diseño completamente al azar con los tratamientos ordenados de forma factorial con cuatro réplicas por tratamiento. La unidad experimental fue el departamento que constó de 15 cerdos para productividad y calidad de la canal, cuatro cerdos para calidad de la carne y dos cerdos para perfil de ácidos grasos. Al final de la prueba, las HE consumieron menos pienso (2,72 vs. 2,85 y 2,92 kg/d; P<0,01) y tendieron a ser más eficientes (3,75 vs. 3,92 y 3,92; P<0,10) que las HC y los MC. Asimismo, las HE presentaron canales con más grasa que las HC y los MC. 2.

(22) Resumen (P<0,001). Sin embargo, el rendimiento de jamón perfilado (18,2 vs. 16,8 y 17,2%), paleta perfilada (11,6 vs. 10,9 y 10,9%) y lomo (4,0 vs. 3,5 y 3,6%) fue mayor (P<0,001) para HE que para HC y MC. No se observó efecto alguno del sexo sobre las pérdidas de peso de los jamones durante el proceso de curado, la composición química de la carne o el perfil de ácidos grasos de la grasa subcutánea. Al final de la prueba (de 20 a 145 y de 30 a 156 kg PV, según tratamiento), los cerdos sacrificados con 145 kg PV consumieron menos pienso (2,74 vs. 2,92 kg/d; P<0,001) y fueron más eficientes (3,75 vs. 3,97; P<0,01) que los cerdos sacrificados con 156 kg PV. Un incremento del peso al sacrificio de 145 a 156 kg PV aumentó el peso y el rendimiento de la canal (P<0,05) y el pH2 y pH24 (P<0,01) y tendió a disminuir el rendimiento de jamón perfilado (17,6 vs. 17,3%; P<0,10). El peso al sacrificio no influyó sobre las pérdidas de peso de los jamones durante el curado ni sobre la calidad de la carne (P>0,10). Se concluye que las hembras enteras son una buena alternativa a las hembras castradas para la producción de cerdo Ibérico en intensivo. Además, se recomienda la disminución del peso al sacrificio de 156 a 145 kg en este tipo de producción.. En el segundo ensayo se utilizaron 168 cerdos cruce de hembra Retinto IB con macho Duroc Danés con una edad de 152 d (42 ± 2,5 kg de peso vivo, PV) para estudiar la influencia del sexo y la castración de las hembras (hembra entera, HE vs. hembra castrada, HC vs. macho castrado, MC) y el nivel de alimentación (ad libitum, AL vs. 82% del consumo AL de 152 a 201 d y 72% de 202 a 263 d de edad) sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea. De 264 d de edad hasta el sacrificio a 317 d de edad, todos los cerdos consumieron pienso AL. Las muestras de carne se tomaron del m. Longissimus dorsi a la altura de la última costilla y las de grasa subcutánea a la altura de la inserción del. 3.

(23) Resumen rabo. El diseño experimental fue completamente al azar con los tratamientos ordenados de forma factorial con cuatro réplicas por tratamiento. La unidad experimental fue el departamento con siete cerdos para productividad y calidad de la canal y cinco cerdos para calidad de la carne y perfil de ácidos grasos. Las HE tendieron a ser más eficientes que las HC y los MC (4,07 vs. 4,33 y 4,27; P<0,10). Además, las HE tuvieron menos grasa en la canal (P<0,05), más rendimiento de partes nobles perfiladas (32,8 vs. 30,6 y 30,4%; P<0,01) y menos grasa (P <0,01) y más proteína (P <0,05) en el m. Longissimus dorsi que las HC y los MC. De 152 a 263 d de edad, los cerdos alimentados AL crecieron más (P<0,001) que los cerdos restringidos. Sin embargo, de 264 a 317 d de edad, cuando todos los cerdos consumieron pienso AL, los cerdos que habían estado restringidos previamente comieron más pienso (P<0,05), crecieron más (P<0,001) y fueron más eficientes (P<0,01) que los cerdos que habían consumido pienso AL. Al final de la prueba, los cerdos que habían estado restringidos crecieron menos (640 vs. 699 g/d; P<0,001) y en consecuencia, tuvieron menor peso al sacrificio (147,0 vs. 157,5 kg; P<0,05) que los cerdos que consumieron pienso AL durante toda la prueba. Asimismo los cerdos que estuvieron restringidos tendieron a presentar menor rendimiento de la canal (P<0,10) que los cerdos alimentados AL. Sin embargo, los cerdos que tuvieron alimentación restringida tendieron a presentar menos grasa en la canal y mayor rendimiento de partes nobles perfiladas (31,8 vs. 30,6%) que los cerdos alimentados AL (P<0,10). El nivel de alimentación no influyó sobre la calidad de la carne. Se concluye que las hembras enteras tienen mejores rendimientos productivos y mayor rendimiento de partes nobles que las hembras castradas. Asimismo, la restricción del consumo aplicada de 152 a 263 d de edad mejora el rendimiento de partes nobles perfiladas sin perjudicar la conversión alimenticia o la calidad de la carne. La utilización. 4.

(24) Resumen de hembras enteras y restringir el consumo voluntario son prácticas aconsejables para la producción de cerdo Ibérico en sistemas intensivos.. En el tercer ensayo se utilizaron 60 hembras cruces de madres Retinto IB con padres Duroc Danés de 80 ± 2,0 d de edad (17,6 ± 0,13 kg de peso vivo, PV) para estudiar la influencia de la castración (HE, hembras enteras vs. hembras castradas, HC) sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea. Los animales se castraron con 92 d de edad (26,1± 0,19 kg PV) y se sacrificaron con 267 d de vida (143,6 ± 6,49 kg PV). Las muestras de carne se tomaron del m. Longissimus dorsi a la altura de la última costilla y las muestras de grasa subcutánea a la altura de la inserción del rabo. El diseño experimental fue completamente al azar con los tratamientos ordenados de forma factorial con cinco réplicas por tratamiento. La unidad experimental fue el departamento con seis animales para productividad y calidad de la canal y cuatro para calidad de la carne y perfil de ácidos grasos. En el global de la prueba (18 a 144 kg PV), las HE comieron menos pienso y fueron más eficientes que las HC (P<0,05). Además, las HE tuvieron menor rendimiento de la canal (P<0,01) y espesor de grasa a la altura del m. Gluteus medius (P<0,05) y tendieron a presentar menor espesor de grasa dorsal a nivel P2 (P<0,10) que las HC. Las HE tuvieron mayor rendimiento de paletas a 2 h y a 24 h post mortem (P<0,05) y tras el perfilado (P<0,10) que las HC. El m. Semimembranosus de las HE tendió a presentar menor pH24 que el mismo músculo de las HC (P<0,10). Además, el m. Longissimus dorsi de las HE tuvo menos grasa y más humedad que el mismo músculo de las HC (P<0,05). La carne de las HE presentó mayor luminosidad (L*; P<0,01), mayor tendencia al rojo (a*; P<0,001) y mayor intensidad del color (mayor c*; P<0,001) que la carne de las HC. La grasa subcutánea fue más saturada en las HC que. 5.

(25) Resumen en las HE (P<0,05), en gran parte debido al mayor contenido de ácido palmítico (P<0,05) y menor en ácido linolénico (P<0,05). Se concluye que las hembras enteras tienen menor rendimiento de la canal pero presentan mejores rendimientos productivos y mayor rendimiento de paletas que las hembras castradas sin que la castración afecte a la calidad de la carne. Por lo tanto, cuando se consideran el bienestar animal, el coste de la castración, los rendimientos productivos y la calidad de la canal y la carne, las hembras enteras son una buena alternativa a las hembras castradas en la producción de cerdo Ibérico en sistemas intensivos.. En el cuarto ensayo se utilizaron 180 cerdos (19 ± 2,5 kg de peso vivo, PV y 80 ± 10 d de edad) para estudiar la influencia del sexo (hembra entera, HE vs. macho castrado, MC) y la línea paterna (Duroc Danés, DD vs. Duroc Estándar Degesa, DE vs. Retinto IB, RIB) sobre la productividad, la calidad de la canal y la carne y el perfil de ácidos grasos de la grasa subcutánea en cerdos sacrificados con 145 kg PV. En todos los casos, la línea materna fue Retinto IB puro. Las muestras de carne se tomaron del m. Longissimus dorsi a la altura de la última costilla y las de grasa subcutánea a la altura de la inserción del rabo. En este ensayo el perfil de ácidos grasos sólo se determinó en las muestras de los cerdos procedentes de las líneas paternas DD y DE. El diseño experimental fue completamente al azar con los tratamientos ordenados de forma factorial con cinco réplicas por tratamiento. La unidad experimental fue el departamento con seis cerdos para productividad y calidad de la canal, tres cerdos para calidad de la carne y cinco cerdos para perfil de ácidos grasos. De 19 a 145 kg PV, las HE comieron menos pienso (2,61 vs. 2,81 kg/d; P<0,05) y fueron más eficientes (4,10 vs. 4,41; P<0,05) que los MC. Asimismo, las HE tuvieron menor rendimiento de la canal (P<0,01) y menos grasa en la canal (P<0,05) y en la carne (P<0,01) que los MC. Sin. 6.

(26) Resumen embargo, las HE tuvieron mayor rendimiento de jamón perfilado (18,4 vs. 17,8%; P<0,10), paleta perfilada (11,7 vs. 11,3%; P<0,05) y lomo (4,3 vs. 3,8%; P<0,001) que los MC. El sexo no influyó sobre el perfil de ácidos grasos de la grasa subcutánea (P>0,10). Los cruces de IB x Duroc crecieron más (689 vs. 549 g/d; P<0,001) y tuvieron mejor conversión (3,90 vs. 4,99; P<0,001) que los cerdos IB puros. Asimismo, los cerdos IB puros necesitaron 49 d más de prueba que los cerdos cruzados con líneas Duroc para alcanzar el mismo peso al sacrificio (311 y 262 d de edad para los cerdos IB puros y para los cruzados con líneas Duroc, respectivamente). No se detectaron diferencias en productividad entre las dos líneas Duroc utilizadas (DD vs. DE). Los cerdos IB puros tuvieron más grasa en la canal (P<0,001) y mayor pH a 2 y a 24 h post mortem (P<0,001) que los cruces con Duroc. Los cerdos cruzados con Duroc tuvieron mayor rendimiento de jamón perfilado (19,7 vs. 14,8%) y de paleta perfilada (12,3 vs. 9,9%) y mayores pérdidas de peso de los jamones durante el curado que los cerdos IB puros (P<0,001). La carne de los cerdos IB puros tuvo más grasa (P<0,05), fue más roja (a*; P<0,001) y tuvo mayor intensidad del color (mayor c* y menor Hº; P<0,01) que la de los cruces de IB x Duroc. No se observó ningún efecto sobre el perfil de ácidos grasos de la grasa subcutánea al remplazar la línea paterna DD por la DE (P>0,10). Se concluye que el uso de hembras enteras mejora la productividad y el rendimiento de partes nobles respecto al uso de machos castrados. La línea paterna Duroc Danés es una buena alternativa a la Duroc Degesa y a la Retinto Ibérico para la producción de cerdos Ibéricos producidos en sistemas intensivos.. 7.

(27) ABSTRACT.

(28) Abstract ABSTRACT. The general aim of this Doctoral Thesis has been to study the influence of factors that influence growth performance and carcass and meat quality of Iberian (IB) pigs reared under intensive management systems. The influence of gender and castration of females, slaughter weight, feed restriction and terminal sire line were studied. To reach these goals, four trials were carried out.. In the first trial a total of 360 IB dam x Spanish Duroc sire pigs was used to study the influence of gender and castration (intact females, IF vs. castrated females, CF vs. castrated males, CM) and slaughter weight (SW; 145 vs. 156 kg body weight, BW) on performance and carcass and meat quality. Pigs that were slaughtered with 145 kg BW (251 d of age) began the trial with 20 kg BW (80 d of age) and pigs that were slaughtered with 156 kg BW (268 d of age) began the trial with 30 kg BW (97 d of age). Meat samples were taken at m. Longissimus dorsi at the level of the last rib and backfat (BF) samples were taken at the tail insertion. Fatty acid profile of BF was not analysed in the pigs slaughtered at 156 kg BW and therefore only the fatty acid profile of each gender from pigs slaughtered at 145 kg BW were compared. There were six treatments with four replicates each. The experimental unit was a pen (15 pigs for productive performance and carcass quality, four pigs for meat quality and two pigs for fatty acid profile of BF). For the entire experiment, IF ate less feed (2.72 vs. 2.85 and 2.92 kg/d; P<0.01) and tended to be more efficient (3.75 vs. 3.92 and 3.92; P<0.10) than CF and CM. No differences were detected for average daily gain or SW between genders. Carcasses from IF were less fatter than carcasses from CF and CM (P<0.001). However, trimmed ham (18.2 vs. 16.8 and 17.2%), trimmed shoulder (11.6 vs. 10.9 and. 9.

(29) Abstract 10.9%) and untrimmed loin (4.0 vs. 3.5 and 3.6%) yield was higher (P<0.001) for IF than for CF and CM. Gender did not affect ham weight losses during ripening, meat chemical composition or fatty acid profile of BF (P>0,10). For the entire experiment (from 20 to 145 and from 30 to 156 kg BW, respectively), pigs slaughtered at 145 kg BW ate less feed (2.74 vs. 2.92 kg/d; P<0.001) and were more efficient (3.75 vs. 3.97; P<0.01) than pigs slaughtered at 156 kg BW. An increase in SW from 145 to 156 kg BW increased carcass weight and carcass yield (P<0.05) and pH2 and pH24 (P<0.01) and tended to reduce trimmed ham yield (17.6 vs. 17.3%; P<0.10). Slaughter weight did not affect ham weight losses during ripening or meat quality (P>0.10). It is concluded that intact females are an alternative to castrated females for intensive production of Iberian pigs. Also, the reduction in slaughter weight from 156 to 145 kg body weight is recommended for this type of production.. In the second trial, IB × Duroc pigs (n=168), with an average age of 152 d (42 ± 2 kg) were used to investigate the influence of feeding regimen (ad libitum access to feed, AL vs. 82% of AL from 152 to 201 d of age and 72% from 202 to 263 d of age, FR) and gender (intact females, IF vs. castrated females, CF vs. castrated males, CM) on growth performance and carcass and meat quality. For the last 54 d before slaughter at 317 d of age, all pigs had AL access to feed. Meat samples were taken at m. Longissimus dorsi at the level of the last rib. Between 152 and 263 d of age, pigs consuming AL had greater (P<0.001) ADG and G:F than FR pigs. However, when all pigs received AL access to feed (264 to 317 d of age), ADFI (P<0.05), ADG (P<0.001), and G:F (P<0.01) were increased in FR pigs compared to AL pigs. Across the entire feeding period (152 to 317 d of age), ADG of FR pigs was less (P<0.001) than that of AL pigs. Feed restricted pigs tended to have greater (P<0.10) yields of trimmed hams and shoulders and less carcass. 10.

(30) Abstract fat than AL pigs; yet, feeding regimen did not (P>0.10) affect pork quality. Intact females tended (P<0.10) to have greater G:F and produced carcasses with less (P<0.05) fat, greater (P<0.01) proportions of primal cuts and increased (P<0.05) CP in the LM than CF and CM. It was concluded from this experiment that feed restriction applied from 152 to 263 d of age improved primal cut yields without affecting gain:feed, pork quality and cured ham production traits. Moreover, intact females were superior to their castrated counterparts (particularly castrated females) for performance and primal cuts yield traits. Therefore, feed restriction, coupled with the use of intact versus castrated females, can be recommended as acceptable practices for the production of Iberian pigs under intensive conditions.. In the third trial a total of sixty crossbred (IB dam x Duroc sire) females, 80 d of age (17.6 ± 0.13 kg body weight, BW), was used to investigate the effect of castration on productive performance, carcass and meat quality and fatty acid profile of backfat (BF). There were two treatments (intact females, IF vs. castrated females, CF) and five replicates of six pigs per treatment. Pigs were ovariectomized at 92 d of age (26.1 ± 0.19 kg BW) and slaughtered at 267 d of age (143.6 ± 6.49 kg BW). Meat samples were taken at m. Longissimus dorsi at the level of the last rib and BF samples were taken at the tail insertion. For the global experiment (18 to 144 kg BW), IF ate less feed and were more efficient than CF (P<0.05). Also, IF had less carcass yield (P<0.01) and fat thickness at the m. Gluteus medius (P<0.05) and tended to have lower carcass BF depth (P<0.10) than CF. However, IF had higher shoulder yield at 2 and at 24 h post mortem (P<0.05) and after trimmed (P<0.10) than CF. The pH24 of the m. Semimembranosus tended to be lower for IF than for CF. Also, IF had more moisture (71.0 vs. 69.1%) and less fat (6.64 vs. 9.12%) in the m. Longissimus dorsi than CF (P<0.05). Meat from IF. 11.

(31) Abstract was more lightness (L*; P<0.01), redder (a*; P<0.001) and had more intensive colour (c*; P<0.001) than meat from CF. Backfat was more saturated in CF than in IF (P<0.05), mostly because of the higher palmitic acid (P<0.05) and the lower linolenic acid (P<0.05) content. It is concluded that intact females have better productive performance and shoulder yield but less carcass yield than castrated females and that castration does not improve meat quality. Therefore, when animal welfare, cost of castration, productive performance and carcass and meat quality traits are considered, the use of intact females rather than castrated females is recommended for the production of Iberian pigs reared under intensive management systems.. In the fourth trial a total of 180 pigs (19 ± 2.5 kg body weight, BW and 80 ± 10 d of age) was used to study the effect of sex (intact female, IF vs. castrated male, CM) and terminal sire line (Danish Duroc, DD vs. Spanish Duroc, SD vs. Retinto IB, RIB) on performance and carcass and meat quality of pigs sacrificed at 145 kg BW (262 and 311 d of age for Duroc crossbreds and for pure IB pigs, respectively). The female line used was pure IB in all cases. Meat samples were taken at m. Longissimus dorsi at the level of the last rib and backfat (BF) samples were taken at the tail insertion. Fatty acid profile of BF was not analysed in the RIB sired pigs and therefore only the two Duroc sire lines (DD vs. SD) of each sex were compared. There were six treatments with five replicates each. The experimental unit was a pen (six pigs for productive performance and carcass quality, three pigs for meat quality and five pigs for fatty acid profile). From 19 to 145 kg BW, IF ate less feed (2.61 vs. 2.81 kg/d; P<0.05) and were more efficient (4.10 vs. 4.41; P<0,05) than CM. Also, IF had lower carcass yield (P<0.01) and less carcass (P<0.05) and muscular fat (P<0.01) than CM. However, IF had higher trimmed ham (18.4 vs. 17.8%; P<0.10), trimmed shoulder (11.7 vs. 11.3%; P<0.05) and loin (4.3. 12.

(32) Abstract vs. 3.8%; P<0.001) yields than CM. Gender did not affect fatty acid profile of BF (P>0.10). Duroc sired pigs grew faster (689 vs. 549 g/d; P<0.001) and had better feed conversion (3.90 vs. 4.99; P<0.001) than RIB sired pigs. Pure IB pigs needed 49 d more than Duroc sire line pigs to reach the pre-planned slaughter weight. No differences were detected for productivity between the two Duroc lines used (DD vs. SD). Pure IB pigs had fatter carcasses (P<0.001) and higher pH at 2 and 24 h post mortem (P<0.001) than Duroc crossbreds. Iberian x Duroc pigs had higher trimmed ham (19.7 vs. 14.8%) and trimmed shoulder (12.3 vs. 9.9%) yields and higher ham weight losses during ripening than pure IB pigs (P<0.001). Meat from IB pigs had more fat (P<0.05) and was redder (a*; P<0.001) and had higher intensity of colour (higher c* and lower Hº; P<0.01) than meat from IB x Duroc pigs. No differences were detected between the fatty acid profile of BF from DD and SD sire lines (P>0.10). It is concluded that productive performance and primal cuts yield are higher for intact females than for castrated males. Danish Duroc sires are a good alternative to Spanish Duroc and Retinto Iberian sires for production of Iberian pigs under intensive systems.. 13.

(33) CHAPTER 1: LITERATURE REVIEW AND OBJECTIVES.

(34) Chap pter 1: Literrature revieew and objecctives 1. Liiterature reeview. 1.1.In Introductionn. T Iberian (IB) pig iss a native dark-haired breed The b of Sppain originaally reared under u free-range condditions, fed on o grass annd acorns an nd slaughterred at heavyy weight (1 160 to k of body weight, BW W). Most caarcasses of IB pigs aree destined to the produ uction 180 kg of hiigh quality cured produucts mainlyy hams, sho oulders and loins becauuse of the strong s consuumer demannd for prodducts derivedd from anceestral pigs (López-Bote ( e, 1998). Neear of 12% of 42.6 miillions of haams and shooulders produced in Sppain in 2006 derivates from E 2006. Figure 1)). IB piigs (Alimenntación en España,. Figure 1. Originn of the ham ms and shouulder produced in Spain (Alimentaación en Esp paña, 20066). 6.8% 2.9 miill. 5..2% 2..2 mill H white pigs Ham. Shoulder white pigs. H Iberian pigs Ham. Shoulder Iberian pigs. 79.1% 33.7 mill 8.9% 3.8 mill. F Free-range f fattening haas importantt consequen nces on the quality q of thhe meat, both for freshh consumptiion and for elaborationn of dry-curred products. In fact, pproducts fro om IB pig free-range f f fattened attaain the highhest prices in i the markeet because of preference by. 15.

(35) Chapter 1: Literature review and objectives consumers. The main reason for this preference is the high oleic acid (C18:1) content in the fat of these pigs, which is mostly due to the high C18:1 content of the acorns that they consume. However, the productivity of pure IB sows (less than 14 piglets weaned/sow/year) and pure IB fattening pigs (feed conversion ratio from 25 to 160 kg BW higher than 5.6) is low. Also, the production of IB pigs reared outdoors has some inconveniences as longer cycles, high cost and the heterogeneousness of the final products. In addition, the production area of acorns and extensive IB pigs is limited and the number of IB pigs has been increased (around 600,000 sows in 2007). Consequently, the growth of the IB pig industry is based primarily on pigs reared indoors and 80% of IB pigs (Ventanas et al., 2007) are currently crossed with Duroc (DU) sires, fed on concentrates under intensive systems and slaughtered at 140 to 150 kg BW. These modifications of the traditional rearing system lead to produce IB drycured products of different quality and price. In order to avoid commercial frauds and to guarantee the consumers rights, the Spanish Ministry of Agriculture, Fishery and Food has enacted a law, called ‘‘Quality Policy’’, to regulate the market of IB products (Boletín Oficial Estado, 2007).. 1.2. Legislation for Iberian pig products. The lack of legislation for IB pig products permitted that no IB products were labelled as such causing important frauds. The Real Decreto 1083/2001 (Boletín Oficial Estado, 2001) was the first law that regulated the ham, shoulder and loin production of IB pigs in Spain. Currently, the Real Decreto 1469/2007 of Boletín Oficial Estado (2007) regulates the production of fresh and cured products of IB pigs in permitted areas of Spain and Portugal. The rule contains the most important factors that determine. 16.

(36) Chapter 1: Literature review and objectives the quality as breed (pure IB or crossbred IB pig), feeding during the fattening period (“montanera”, “recebo”, “cebo campo” or “cebo”) and the age (handling) and requires the pursuit of IB products (Table 1). Genetic and feeding background have to be shown in the label of the IB dry-cured products.. Products labelled as pure IB must derive from a pure IB male and a pure IB female. However, the legislation for the production of dry-cured products labelled as IB allows IB x DU crosses if the IB pig is the maternal line, in order to preserve the IB breed purity. The feeding during the fattening period is classified in four groups: 1) acorn and grass or “montanera”, 2) montanera supplemented with concentrates or “recebo”, 3) exclusively fed on mixed but outdoors for 60 d before to slaughter or “cebo campo” and 4) exclusively fed on mixed indoors until slaughter or “cebo”. The minimum age at slaughter should be of 14 months for “montanera” and “recebo” IB pigs, 12 months for “cebo de campo” IB pigs and 10 months for “cebo” IB pigs.. 17.

(37) Chapter 1: Literature review and objectives Table 1. Law for Iberian pig products (Boletín Oficial Estado, 2007) Classification. Bellota. Recebo. Cebo campo. Feeding. Concentrate-. Concentrate-. montanera. montanera-. Cebo 1. Concentrate. Concentrate. concentrate Beggining of montanera Av. BW2/lot, kg. 92 to 115. 92 to 115. 92 to 115. -. Dates. 1/10 to 15/12. 1/10 to 15/01. -. -. kg BW. > 46. > 29. -. -. Days. ≥ 60. ≥ 60. ≥ 60 d. -. Replacement. Slaughter. -. BW minimum, kg Av. carcass/lot. 117. 117. 117. 117. Minimum/carcass. 108. 108. 108. 108. Minimum age, m. 14. 14. 12. 10. Dates. 15/12 to 15/04. 15/12 to 15/05. -. -. ≤2. ≤2. ≤ 15. -. Pig/ha 1. Minimum distance among feeders and drinkers of 100 m. 2 Average body weight.. 1.3. Productivity of Iberian pigs. There is information about the average daily gain (ADG), but the information available about the average daily feed intake (ADFI) and the feed conversion ratio (FCR) of IB pigs is very scarce. Serra et al (1998) observed that AGD was around 30% higher for Landrace than for IB pigs (Table 2). However, Morales et al. (2002, 2003). 18.

(38) Chapter 1: Literature review and objectives did not found differences on the ADG of IB and Landrace pigs fed on concentrates. However, these authors observed that IB pigs ate 23-32% more and were 25% less efficient than Landrace pigs. The higher voluntary feed intake of IB pigs is associated with digestive tract adaptations, as it is an increased stomach content, lower digesta content in the hindgut compartment and a shorter time of retention of digesta for fermentation. Differences in the FCR between IB and white pigs could be explain mainly by differences in the energy content of their weight gains due to the higher fat content of the carcass from IB pigs. In general, the crossbreed of IB with DU pigs improves ADG and FCR (López-Bote, 1998) respect to pure IB pigs. In fact, Mayoral et al. (1999) found ADG of 315 g for pure IB pigs while other authors (Morcuende et al., 2007; Ramírez and Cava, 2007) have observed ADG from 512 to 598 g for crossbreds with DU pigs. However, these differences also are due to pigs were fed different in these researches.. The IB pigs fed in confinement grew 23% more that those fed under extensive condition (Daza et al., 2006; Table 3). When the average daily energetic intake is similar, the reduction of the observed ADG of the pigs fed with acorn and grass would correspond to the effects of the physical activity (Lachica and Aguilera, 2000), climatic conditions (López-Bote et al., 2000) and to the lower ingestion of digestible protein (Aparicio, 1987). However, Rey et al. (2006) did not found differences for the ADG of IB pigs fed on montanera or indoors with concentrates, acorn or acorn and grass. The cause of this discrepancy could be that ADG of IB pigs of montanera depends of quantity of acorns available that is different each year.. 19.

(39) Chapter 1: Literature review and objectives Table 2. Productivity of different breeds of pigs Breed. Gender1. Feed 5. Body weight, kg 6, 7. Iberian Guadyerbas Landrace SEM8 Probability9 Iberian. Concentrates. CF and IM. 14.3 to 118±11 14.3 to 105±10. Free-range10. 1.5 to 152.75. Iberian11. Concentrates12. CF and CM CM. 37.7 to 86.9 86.9 to 108.2 37.7 to 89.9 89.9 to 107.2. ADG, g2. ADFI, g3. FCR4. Reference. 450 640 10.0 *** 315. -. -. Serra et al. (1998). Mayoral et al. (1999). 550 Morales et al. (2002) 775 3,495 4.73 Landrace 750 765 2,700 3.59 SEM 44.0 199.0 0.488 Probability NS ** * Iberian 74% corn CM 108 to 133 936 3,739 4.00 Morales et al. (2003) Landrace 740 2,574 3.48 Iberian 40% acorn + 613 3,405 5.73 Landrace 20% sorghum 612 2,301 3.81 SEM 72.0 128.0 0.565 Probability breed NS *** + Probability feed13 * + NS Iberian x Duroc14 Concentrates CM Morcuende et al. (2007) 50 to 147.7±10.3 598 ± 40 Duroc x Iberian15 50 to 138.8±5.5 580 ± 35 *16 * Probability 17 Iberian x Duroc 1 Semi-intensive CF 80.1 to 149.719 512b Ramírez and Cava (2007) Duroc 1 x Iberian and CM 91.2 to 165.919 549a Duroc 2 x Iberian18 84.0 to 160.319 561ab Probability * 1 CF: castrated female; IM: intact male; CM: castrated male. 2Average daily gain, g. 3 Average daily feed intake, g. 4 Feed conversion ratio.5 Fed ad libitum on a cereal based commercial diet under intensive conditions. 6 Iberian pigs were six weeks older than Landrace pigs. 7 Standard deviation of the mean. 8 Standard error of the mean. 9 NS P>0.10; + P<0.10; * P<0.05; ** P<0.01; *** P<0.001. a, b Means without a common superscript letter within a column differ (P<0.05). 10 Fed ad libitum with natural resources, except during lactation (from 1.25 to 14.31 kg). It was spring from 14.31 to 56.00 kg, summer from 56.00 to 76.63 kg, autumn from 76.63 to 83.25 kg, winter from 83.25 to 96.88 kg and montanera from 96.88 to 152.75 kg. 11 Iberian pigs were restricted to 75% of ad libitum feed intake. At the beginning of the trial, Iberian and Landrace pigs were 195 and 150 d of age, respectively. 12 In the second phase (from 86.9 to 108.2 and from 89.9 to 107.2 for Iberian and Landrace pigs, respectively), half of the replicates of each breed consumed a diet with 75.4% corn. The other half of replicates consumed a diet with 37.6% corn, 27.5% sorghum and 12.5% semi-decorticated acorn but differences between diets did not reach significances for any trait and interaction breed*feed was not significant (P>0.10). 13 The interaction breed*feed was not significant (P>0.10). 14 Iberian dam x Duroc sire slaughtered at 235 d of age. 15 Duroc dam x Iberian sire slaughtered at 235 d of age. 16 For slaughter weight. 17 The genotype Duroc 1 corresponded to pigs selected for the production of drycured meat products with a high level of fattening. 18 The genotype Duroc 2 corresponded to pigs selected for meat production with high percentages of meat cuts and low carcass fat. 19 All pigs were slaughtered at 316 d of age.. 20.

(40) Chapter 1: Literature review and objectives Table 3. Productivity of Iberian pigs finishing fed on montanera or with concentrates Breed Iberian Silvela Iberian Lampiño Iberian Entrepelado Iberian Retinto Iberian Mamellado Iberian Torbiscal Iberian Torbiscal SEM montanera SEM concentrates Probability Iberian Torbiscal. SEM Probability Iberian Torbiscal. Feed Montanera5, 6. Gender1 CM. Body weight, kg 53 to 164. Montanera 92 d Concentrates 92 d8. CM. 102.0 to 152.4 102.0 to 159.0. Montanera 97 d Concentrates 97 d Acorn 97 d9 Acorn + Grass 97 d10. CM. FR11112 CDC28 + FR83. CM. CDC65 + FR46. SEM FR13 SEM CDC SEM FR + CDC Probability FR14 Iberian Torbiscal. CD111. Concentrates 167 d Montanera 117 d15. SEM Probability. CM. 100.4 to 152.3 100.4 to 156.9 100.4 to 158.8 100.4 to 150.4 12.511 NS11 100.9 to 144.5 99.3 to 111.1 CDC28 111.1 to 142.2 FR83 99.3 to 142.2 99.9 to 127.6 CDC65 127.6 to141.5 FR46 99.9 to 141.5 101.5 to 145.9. 23.5 to 99.71617 71.7 to 101.4 81.6 to 102.618 99.7 to 131.4 101.4 to 149.7 102.6 to 154.3 0.99 and 0.3819. 1. ADG, g2 406.5±4.517 422.0±10.05 418.0±6.24 428.8±4.21 499.2±13.87 468.9±5.83 501.5 653.4 26.02 11.12 * 535 582 602 515 NS 392.8a 421.9 377.3a 388.5 426.0 303.0b 375.0 400.1 23.1 16.9 18.9 * 457.0 178.0 126.0 270.2b 412.8a 441.8a 5.52 *. ADFI, g3 -. FCR4 -. 3,720 0 2,600 2,800 3,100 2,500 1,500 1,300 -. 5.69 5.47 8.43 10.32 -. -. -. Reference Barba et al. (2000). Daza et al. (2006). Rey et al. (2006). Daza et al. (2007a). Daza et al. (2007b). Castrated male. 2Average daily gain, g. 3 Average daily feed intake, g. 4 Feed conversion ratio. 5 Fed on acorn and grass, exclusively. 6 From 116 to 164 kg. 7 Standard deviation of the mean. 8 Fed ad libitum on a commercial diet under intensive conditions. 9 Under intensive conditions with 5-7 kg/d of acorn. 10 Under intensive conditions with 5-7 kg/d of acorn and 2 kg/d of grass. 11 For slaughter weight. 12 FR111: pigs fed, under free-range conditions, with acorns and grass for 111 d. CDC28 + FR83: pigs fed on concentrates in confinement for 28 initial d and in free-range with acorns and grass for 83 d. CDC65 + FR46: pigs fed on concentrates in confinement for 65 initial d and in free-range with acorns and grass for 46 d. CDC111: pigs fed on concentrates in confinement for 111 d. The ADFI is for concentrate exclusively, in all cases. Probability for CDC and CDC + FR was not significant (P>0.10). 13 Standard error of the mean. 14 NS P>0.10; * P<0.05. a, b Means without a common superscript letter within a column differ (P<0.05). 15 With 0.6 pigs/ha. 16 Begin the montanera with 8 months of age. 17 Begin the montanera with 12 months of age. 18 Begin the montanera with 14 months of age. 19 For initial and final body weight, respectively.. 21.

(41) Chapter 1: Literature review and objectives 1.4. Measures of carcass quality. Yield, fat thickness, carcass length, perimeter and length of carcass, ham and tarsus, pH, shrink loss during chilling, weight and yield of primal cuts and ham weight loss during ripening are traits that define the carcass quality.. 1.4.1. Carcass yield. The carcass yield is the proportion between the carcass weight and the live BW at slaughter. Carcass yield can be measured in hot carcass after slaughter or in cold carcass after chilling. The carcass yield of a pig conventionally includes the head, feet, tail and skin and is usually between 70 and 80% of its live BW. The loss is mostly blood and internal organs. Many factors influence carcass yield such as breed, gender, fibre content of the diet, age and BW at slaughter, transport conditions and time of faster before the slaughter. In white pigs, carcass yield increases by about 0.1 percentage units for each mm increase in P2 backfat (BF) depth between 8 and 18 mm (Kyriazakis and Whittemore, 2006). The carcass yield increases with fat carcass content because in pigs most of the fat is deposited in the carcass (subcutaneous and intermuscular) and only about 10% is in the abdomen, to be discarded with the internal organs. Then, heavier animals tend to be fatter, and fatter animals have higher carcass yield than leaner animals at any given BW. Consequently, the carcass yield is higher for IB pigs than for white pigs (Serra et al., 1998) with crossbreds of IB x DU pigs being intermediate (Table 4). However, there is no scientific information available that compare the carcass yield of pure IB pigs and IB dam x DU sire pigs. Morcuende et al. (2007) and Ramírez and Cava (2007) studied the carcass yield of IB x DU pigs but they did not compare. 22.

(42) Chapter 1: Literature review and objectives with pure IB pigs. These authors obtained carcass yields from 78.6 to 82.8% for IB x DU pigs, while the carcass yield of IB pigs was between 76.94 and 86.92% (Serra et al., 1998; Barba et al., 2000; Daza et al., 2006).. On the other hand, in general the average carcass yield is higher for IB pigs reared outdoors and fed with acorn and grass (81.4%) than for IB pigs fed on concentrates (80.2%; Table 5). However, Daza et al. (2007a) did not found differences between the carcass yield of IB pigs reared outdoors and indoors. Also, Daza et al. (2006) and Rey et al. (2006) found that carcass yield was higher for IB pigs fed on concentrates that for IB pigs fed on montanera. The higher crude fibre consumption in pigs fed extensively reduced the carcass yield, probably due to an increase of digesta content in the caecum and colon and to the additional quantity of water that the fibre attracts toward the intestine.. 23.

(43) Chapter 1: Literature review and objectives. Table 4. Carcass weight and carcass yield of Iberian, Landrace and Iberian x Duroc pigs Breed. Feed. Gender1. Slaughter weight, kg. Carcass weight, kg. Carcass yield, %. Reference. Iberian Guadyerbas. Concentrates2. CF. 118±113, 4. 93.1±1.9. 78.6±0.7. Serra et al. (1998). and IM. 105±10. 76.2±1.5. 72.4±0.5. -. ***. ***. 147.7±10.3. 118.2±8.9. 80.0±0.9. Duroc x Iberian7. 138.8±5.5. 111.6±4.9. 80.4±0.9. Probability. *. NS. NS. CF. 149.711. 124.6b. 82.8a. and CM. 165.911. 135.8a. 81.9a. Duroc 2 x Iberian9. 160.311. 125.9ab. 78.6b. SEM10. -. 2.04. 0.62. Probability. -. *. **. Landrace Probability 5 Iberian x Duroc6. Iberian x Duroc 18 Duroc 1 x Iberian. Concentrates. Semi-intensive. CM. 1. Morcuende et al. (2007). Ramírez and Cava (2007). CF: castrated female; IM: intact male; CM: castrated male. 2 Fed ad libitum on a commercial diet under intensive conditions. 3 Iberian pigs were six weeks older than Landrace pigs. 4 Standard deviation of the mean. 5NS P>0.10; * P<0.05; ** P<0.01; ***: P <0.001. a, b Means without a common superscript letter within a column differ (P<0.05). 6 Iberian dam x Duroc sire slaughtered at 235 d of age. 7 Duroc dam x Iberian sire slaughtered at 235 d of age. 8 The genotype Duroc 1 corresponded to pigs selected for the production of dry-cured products with a high level of fattening. 9 The genotype Duroc 2 corresponded to pigs selected for meat production with high percentages of meat cuts and low carcass fat. 10 Standard error of the mean. 11 All pigs were slaughtered at 316 d of age.. 24.

(44) Chapter 1: Literature review and objectives Table 5. Carcass weight and carcass yield of Iberian pigs fed on montanera or concentrates Breed Iberian Silvela Iberian Lampiño Iberian Entrepelado Iberian Retinto Iberian Mamellado Iberian Torbiscal Iberian Iberian Torbiscal SEM montanera6 SEM concentrates Probability7 Iberian Torbiscal. SEM Probability Iberian Torbiscal. SEM Probability Iberian Torbiscal. SEM Probability. Feed Montanera2, 3. Gender1 CM. Slaughter weight, kg 164. Montanera Montanera 92 d Concentrates 92 d5. CM CM. Montanera 97 d Concentrates 97 d Acorn 97 d8 Acorn + Grass 97 d9. CM. FR11110 CDC28 + FR83 CDC65 + FR46 CD111. CM. Montanera 117 d11. CM. 161.12 152.4 159.0 152.3 156.9 158.8 150.4 12.5 NS 144.5 142.2 141.5 145.9 1.61 NS 131.412 149.713 154.314 0.99 and 0.3815 -. 1. Carcass weight, kg 4. 132.26±1.28 146.99±3.24 132.32±1.61 138.62±0.80 145.91±2.10 143.48±1.76 131.11±16.51 121.31 119.79 1.76 1.79 NS 118.94b 130.04a 126.17ba 123.57ba 10.72 ** 116.3 113.9 113.0 117.4 1.69 NS 104.2b 120.6a 124.9a 1.10 *. Carcass yield, % 81.59±0.28 86.92±0.38 83.73±0.20 84.45±0.13 83.89±0.29 82.99±0.39 76.94 77.97 0.23 0.26 * 78.45b 82.01a 79.56ba 82.16a 1.90 *** 80.5 80.0 79.9 80.5 0.21 NS 79.3 80.6 80.9 0.14 NS. Reference Barba et al. (2000). Fernández et al. (2003) Daza et al. (2006). Rey et al. (2006). Daza et al. (2007a). Daza et al. (2007b). Castrated male. 2 Fed on acorn and grass, exclusively. 3 From 116 to 164 kg. 4 Standard deviation of the mean. 5 Fed ad libitum on a commercial diet under intensive conditions. 6 Standard error of the mean. 7 NS P>0.10; * P<0.05; ** P<0.01; *** P<0.001. a, b Means without a common superscript letter within a column differ (P<0.05). 8 Under intensive conditions with 5-7 kg/d of acorn. 9 Under intensive conditions with 5-7 kg/d of acorn and 2 kg/d of grass. 10 FR111: pigs fed, under free-range conditions, with acorns and grass for 111 d. CDC28 + FR83: pigs fed on concentrates in confinement for 28 initial d and in free-range with acorns and grass for 83 d. CDC65 + FR46: pigs fed on concentrates in confinement for 65 initial d and in free-range with acorns and grass for 46 d. CDC111: pigs fed on concentrates in confinement for 111 d. 11 With 0.6 pigs/ha. 12 Begin the montanera with 8 months of age. 13 Begin the montanera with 12 months of age. 14 Begin the montanera with 14 months of age. 15 For initial and final body weight, respectively.. 25.

(45) Chapter 1: Literature review and objectives 1.4.2. Carcass fat. The main difference between the carcass of IB and white pigs is their fat content. In the final phases of fattening (140 to 160 kg BW), pure IB pigs fed on acorn and grass can reach 60% of carcass fat, 15 cm of BF thickness and 10 to 13% of intramuscular fat (IMF) content (López-Bote, 1998). Serra et al. (1998) observed a BF thickness 27.4 mm higher for IB pigs than for Landrace pigs, fed both on concentrates (Table 6). The average BF thickness in heavy white pigs is from 24.5 to 25.2 in CF and CM slaughtered between 118 and 124 kg BW (Latorre et al., 2004; Peinado et al., 2008). However, the average BF thickness in IB x DU pigs is in the range of 44.2 to 64.0 mm for pigs slaughtered at 138.8 and 165.9 kg, respectively (Morcuende et al., 2007; Ramírez and Cava, 2007). Due to the high energy content of acorns, the elevate age at slaughter and the breed, IB pigs fed with acorns and grass should have more carcass fat than IB pigs fed on concentrates. However, Daza et al. (2006) did not observe differences between the BF thickness of IB pigs reared outdoors or indoors.. Fat that cover the ham generally is measured at m. Gluteus medius (GM) and it is a good indicator of the IMF content. When the fat at GM is very high, consumers reject the hams. Nevertheless, for the manufacture of high quality dry-cured products a high level of fattening is required to development of adequate sensory characteristics during the ripening (Gandemer, 2002). However, the information available about the thickness of fat that cover the ham in IB pigs is very scarce. Ramírez and Cava (2007) observed a ham fat thickness from 27 to 34 mm in crossbred of IB x DU pigs reared under a semiintensive system.. 26.

(46) Chapter 1: Literature review and objectives. Table 6. Carcass fat of Iberian pigs Breed. Feed. Gender1. Slaughter weight, kg. Backfat, mm. Ham fat, mm. Reference. Iberian Guadyerbas Landrace Probability5 Iberian Torbiscal. Concentrates2. CF and IM CM. Concentrates. CM. Semi-intensive. CF and CM. 48.1±1.4 20.7±1.0 *** 54.79 and 32.07 56.07 and 48.57 42b 49a 49a 0.4 * 48.3±6.3 44.2±4.5 NS 63ab 64a 53b 1.8 *. 31ab 34a 27b 1.1 **. Serra et al. (1998). Montanera 92 d6 Concentrates 92 Montanera 117 d. 118±113, 4 105±10 152.4 159.0 131.48 149.79 154.310 0.38 147.7±10.3 138.8±5.5 * 149.716 165.916 160.316 -. Iberian Torbiscal SEM11 Probability Iberian x Duroc12 Duroc x Iberian13 Probability Iberian x Duroc 114 Duroc 1 x Iberian Duroc 2 x Iberian15 SEM Probability. CM. 1. Daza et al. (2006) Daza et al. (2007b). Morcuende et al. (2007). Ramírez and Cava (2007). CF: castrated female; IM: intact male; CM: castrated male. 2 Fed ad libitum on a commercial diet under intensive conditions. 3 Iberian pigs were six weeks older than Landrace pigs. 4 Standard deviation of the mean. 5 NS P>0.10; * P<0.05; ** P<0.01; *** P<0.001. a, b Means without a common superscript letter within a column differ (P<0.05). 6 Fed on acorn and grass exclusively with 0.6 pigs/ha for Daza et al. (2007b). 7 Average of backfat thickness measured in three points real and with ultrasounds, respectively. 8 Begin the montanera with 8 months of age. 9 Begin the montanera with 12 months of age. 10 Begin the montanera with 14 months of age. 11 Standard error of the mean. 12 Iberian dam x Duroc sire slaughtered at 235 d of age. 13 Duroc dam x Iberian sire slaughtered at 235 d of age.14 The genotype Duroc 1 corresponded to pigs selected for the production of dry-cured products with a high level of fattening. 15 The genotype Duroc 2 corresponded to pigs selected for meat production with high percentages of meat cuts and low carcass fat. 16 All pigs were slaughtered at 316 d of age.. 27.

(47) Chapter 1: Literature review and objectives 1.4.3. Carcass length. Carcass length is measured from the posterior edge of the symphysis pubis to the anterior edge of the first rib and can be measured inner or outer, being an average of 40.2 cm higher the outer carcass length than the inner carcass length (Daza et al., 2007b. Table 7). Carcasses with higher length have worse conformation and their evisceration and quartering is more difficult. There is no information that compares the carcass length of IB, white and IB x DU pigs. In general, IB pigs slaughtered between 131.4 and 154.3 kg BW present inner carcass lengths from 80.7 to 83.6 cm (Daza et al., 2007a,b). On the other hand, in heavy weight pigs, inner carcass length is from 83.2 cm in pigs slaughter at 114 kg to 87.6 cm in pigs slaughter at 122 kg BW (Peinado et al., 2008). However, there is no information available about the carcass length of IB dam x DU sire pigs. Carcass length is higher for IB pigs fed on concentrates for 111 d than for IB pigs fed on montanera for 83 or 111 d (Daza et al., 2007a).. 28.

(48) Chapter 1: Literature review and objectives Table 7. Carcass length of castrated males Iberian pigs. Breed. Feed. Iberian Torbiscal. FR1111 CDC28 + FR83 CDC65 + FR46 CD111. SEM2 Probability3 Iberian Torbiscal. Slaughter weight, kg 144.5 142.2 141.5 145.9 -. Montanera 117 d. Carcass length, cm 81.1b 80.7b 82.1ab 83.6a 0.35 *. 4. Inner lenght. SEM Probability Outer lenght. SEM Probability. Reference Daza et al. (2007a). Daza et al. (2007b) 131.45 149.76 154.37 0.38 131.45 149.76 154.37 0.38 -. 81.2b 83.4a 83.3ab 0.21 * 116.7b 127.3a 124.4a 0.35 *. 1. FR111: pigs fed, under free-range conditions, with acorns and grass for 111 d. CDC28 + FR83: pigs fed on concentrates in confinement for28 initial d and in free-range with acorns and grass for 83 d. CDC65 + FR46: pigs fed on concentrates in confinement for 65 initial d and in free-range with acorns and grass for 46 d. CDC111: pigs fed on concentrates in confinement for 111 d. 2 Standard error of the mean. 3 * P<0.05. a, b Means without a common superscript letter within a column differ (P<0.05). 4 Fed on acorn and grass exclusively with 0.6 pigs/ha. 5 Begin the montanera with 8 months of age. 6 Begin the montanera with 12 months of age. 7 Begin the montanera with 14 months of age.. 1.4.4. Perimeter and length of hams. Perimeter and length of hams define the conformation of the ham. Generally, ham perimeter is measured at the widest side and ham length is measured from the anterior edge of the symphysis pubis to the hock joint. In Spain, consumers prefer hams narrow and with high length. The information available about the perimeter of IB hams is very scarce. Daza et al. (2007a) observed that hams from IB pigs fed on concentrates have a perimeter 5% higher than hams from IB pigs fed on montanera (Table 8). There is no information about the ham length of IB pigs. Ham length is related with the percentage of bone in the carcass and with the potential capacity to muscle development because. 29.

(49) Chapter 1: Literature review and objectives there is a high positive correlation between the length of the extremities and the final BW.. Table 8. Ham perimeter of castrated males Iberian pigs (Daza et al., 2007a). Breed. Feed. Slaughter weight, kg. Ham perimeter, cm. Iberian Torbiscal. FR1111. 144.5. 65.2b. CDC28 + FR83. 142.2. 65.6b. CDC65 + FR46. 141.5. 65.4b. CD111. 145.9. 68.8a. SEM2. 0.28 3. Probability. -. *. 1. FR111: pigs fed, under free-range conditions, with acorns and grass for 111 d. CDC28 + FR83: pigs fed on concentrates in confinement for 28 initial d and in free-range with acorns and grass for 83 d. CDC65 + FR46: pigs fed on concentrates in confinement for 65 initial d and in free-range with acorns and grass for 46 d. CDC111: pigs fed on concentrates in confinement for 111 d. 2 Standard error of the mean. 3 * P<0.05. a, b Means without a common superscript letter within a column differ (P<0.05).. 1.4.5. Perimeter and length of tarsus. In the IB pigs, other important measures are the perimeter and the length of the tarsus. Generally, tarsus perimeter is measured at the medium of the tarsus and tarsus length is measured from the hock joint to the beginning of the hoof. Consumers of IB hams show a clear preference for long pieces with a narrow tarsus because these characteristics are associated with greater percentage of IB blood (Figure 2) and, consequently, with higher quality of the product. However, there is no information about the dimensions of tarsus of IB pigs.. 30.

(50) Chapter 1: Literature review and objectives Figure 2. Comparison between perimeter and length of hams from white (a) and Iberian (b) pigs a). b). 1.4.6. pH. pH of the primal cuts affect water migration and consequently, the rate and extension of the ripening process and the acceptability of the cured products (RuízCarrascal et al., 2000; Bañón et al., 2003). Then, pH value of pig meat gives information about the capacity to the processing of the meat and is commonly influenced by several factors that affect post mortem metabolism such as breed, gender, physical activity, stress and carcass temperature. pH representatives of the carcass generally are measured in m. Semimembranosus (SM), m. Longissimus dorsi (LM), m. Bíceps femoris (m. BF) or m. Psoas major (PM). Serra et al. (1998) observed in IB pigs that pH of the m. Longissimus lumborum (LL) was 0.09 units higher and 0.05 units lower than pH SM at 45 min and 24 h post mortem, respectively. Ramírez and Cava (2007) observed that pH at 45 min and at 24 h post mortem were 0.01 units higher in m.. 31.

(51) Chapter 1: Literature review and objectives BF than in LM of IB x DU pigs. Also, Morcuende et al. (2007) found higher pH in PM than in LM being m. BF intermediate in IB pigs (Table 9).. In the post mortem muscle, supply of oxygen is stopped and consequently ATP must be regenerated by an anaerobic glycolytic breakdown of glycogen. The accumulation of lactic acid contributes to an acidification and thus to decreased pH in the muscle. A normal pH decrease from pH 7.2 in the living muscle to an ultimate pH (pHu at 24 h post mortem) of 5.5 that can be observed in well-fed unstressed genetically unaffected pigs, depending on the muscle and muscle glycogen level. In a short term pre-slaughter stressed pigs, the pH decreases faster that leads to pale, soft and exudative (PSE) meat. The pH of PSE meat at 45 min post mortem is lower than 6.2 and the temperature is higher than 37ºC. The incidence of PSE meat is very low in IB pigs.. On the other hand, a pre-slaughter stress for a long term, results in a less extended pH decrease and in a high pHu. This meat is dark and firm and has a dry surface (DFD). The pH of DFD meat at 24 h post mortem is higher than 6.2. Although there is not information about the incidence of DFD meat, IB pigs are inclined to present it because normally arrive to the slaughterhouse with low levels of glycogen (Ventanas and Córdoba, 1992).. Serra et al. (1998) did not find differences between the pH of LL or SM at 45 min post mortem of IB and Landrace pigs. However, at 24 h post mortem, IB pigs had higher pH than Landrace pigs in both muscles. There is no information that compares the pH of IB and IB dam x DU sire pigs. There is no information available about the pH of IB pigs fed on montanera or concentrates.. 32.

(52) Chapter 1: Literature review and objectives Table 9. pH of Iberian pig muscles Breed Feed Gender1 Slaughter weight, kg pH 45 min pH 24 h Reference 2 3, 4 Iberian Guadyerbas Concentrates CF and Serra et al. (1998) 118±11 LL5 IM 5.75 (0.02) 6.49 (0.06)6 105±10 SM7 6.40 (0.06) 5.80 (0.03) Landrace 5.59 (0.02) LL 6.37 (0.04) SM 6.46 (0.05) 5.58 (0.02) Probability LL8 NS *** NS *** Probability SM Iberian x Duroc Concentrates CM 6.00 Morcuende et al. (2007) 147.7±10.3 Duroc x Iberian 6.04 138.8±5.5 0.03 SEM9 NS Probability m. BF10 6.01ab 11 LM 5.92b 12 PM 6.14a SEM 0.03 * Probability Semi-intensive CF and 149.715 Ramírez and Cava (2007) Iberian x Duroc 113 LM CM 5.7 5.7a m. BF 5.8a 5.8a 15 Duroc 1 x Iberian 165.9 LM 5.8 5.5ab a m. BF 5.9 5.7a 14 15 Duroc 2 x Iberian 160.3 LM 5.8 5.1b b m. BF 5.6 5.2b SEM LM 0.05 0.07 SEM m. BF 0.05 0.06 NS * Probability LM ** *** Probability m. BF 1 CF: castrated female; IM: intact male; CM: castrated male. 2 Fed ad libitum on a commercial diet under intensive conditions. 3 Iberian pigs were six weeks older than Landrace pigs. 4 Standard deviation of the mean. 5 Longissimus lumborum. 6 Between brackets, standard error of the mean. 7 Semimembranosus. 8 NS P>0.10; * P<0.05; ** P<0.01; *** P<0.001. a, b Means without a common superscript letter within a column differ (P<0.05). 9 Standard error of the mean. 10 Bíceps femoris. 11 Longissimus dorsi. 12 Psoas major. 13 The genotype Duroc 1 corresponded to pigs selected for the production of dry-cured products with a high level of fattening. 14 The genotype Duroc 2 corresponded to pigs selected for meat production with high percentages of meat cuts and low carcass fat. 15 All pigs were slaughtered at 316 d of age.. 33.

(53) Chapter 1: Literature review and objectives 1.4.7. Shrink loss. The shrink loss during chilling (4º C for 24 h) includes evaporative loss and can be calculated as the relation between the difference in weight before and after chilling and the pre-chilling weight of carcass or of primal cuts. Shrink loss increases with the area of exposition and consequently, shrink loss will be greater when is measured in the whole carcass than when is measured in hams and shoulders, exclusively. Cisneros et al. (1996) and Lebret et al. (2001) have reported shrink loss of carcass in white pigs between 2 and 3%. However, Calini (2000) found shrink loss of 1% in hams of heavy white pigs slaughtered at 160 kg BW. Also, the shrink loss decreases with the increase of carcass fat and then should be higher for white pigs than for pure IB pigs, being IB x DU pigs intermediate. Also, shrink loss should be higher for IB pigs fed on concentrates than for IB pigs fed on montanera. However, there is no information available about the shrink loss of IB or IB dam x DU sire pigs reared outdoors or indoors.. 1.4.8. Primal cuts. Primal cuts are the portion of the carcass with higher economic value (hams, shoulders and loins). In IB pigs, the primal cuts are a 25 to 30% of carcass weight (Table 10) but are an 80 to 90% of their economic value. Weights and yields of primal cuts generally are measured fresh (at 2 h post mortem), after chilling (at 24 h post mortem) and after trimmed. Trimming of hams and shoulders consists in eliminate a part of the external fat and skin to get the commercial form requires by the market. The commercial form depends of the type of ham. In IB hams, trimming finishes in point while in hams from white pig finishes in round. In general, the weight of primal cuts is. 34.