CUANTIFICACIÓN DE LA DESAPARICIÓN DE NUTRIENTES DE LA LUZ DEL TUBO DIGESTIVO DIGESTIBILIDAD

Texto completo

(1)

DIGESTIBILIDAD

(2)

Chapter 1 The animal and its food

4

Table 1.1 Composition of some plant and animal products expressed on a fresh basis and a dry matter basis

Water Carbohydrate Lipid Protein Ash

Fresh basis (g/kg) Turnips 910 70 2 11 7 Grass (young) 800 137 8 35 20 Barley grain 140 730 15 93 22 Groundnuts 60 201 449 268 22 Dairy cow 570 2 206 172 50 Milk 876 47 36 33 8 Muscle 720 6 44 215 15 Egg 667 8 100 118 107

Dry matter basis (g/kg)

Turnips 0 778 22 122 78 Grass (young) 0 685 40 175 100 Barley grain 0 849 17 108 26 Groundnuts 0 214 478 285 23 Dairy cow 0 5 479 400 116 Milk 0 379 290 266 65 Muscle 0 21 157 768 54 Egg 0 24 300 355 321

1.1

WATER

The water content of the animal body varies with age.The newborn animal contains 750–800 g/kg water but this falls to about 500 g/kg in the mature fat animal. It is vital to the life of the organism that the water content of the body be maintained: an animal will die more rapidly if deprived of water than if deprived of food. Water functions in the body as a solvent in which nutrients are transported about the body and in which waste products are excreted. Many of the chemical reactions brought about by enzymes take place in solution and involve hydrolysis. Because of the high specific heat of water, large changes in heat production can take place within the animal with very little alteration in body temperature. Water also has a high latent heat of evaporation, and its evaporation from the lungs and skin gives it a further role in the regulation of body temperature.

The animal obtains its water from three sources: drinking water, water present in its food, and metabolic water, this last being formed during metabolism by the oxidation of hydrogen-containing organic nutrients. The water content of foods is variable and can range from as little as 60 g/kg in concentrates to over 900 g/kg in some root crops. Be-cause of this great variation in water content, the composition of foods is often ex-pressed on a dry matter basis, which allows a more valid comparison of nutrient content. This is illustrated inTable 1.1, which lists a few examples of plant and animal products. The water content of growing plants is related to the stage of growth, being greater in younger plants than in older plants. In temperate climates the acquisition of drink-ing water is not usually a problem and animals are provided with a continuous supply. There is no evidence that under normal conditions an excess of drinking water is harmful, and animals normally drink what they require.

Peso fresco (g/kg) “tal cual”

Nabo Vaca Lechera Leche Músculo Huevo Grano de cebada Maní

Pasto joven (tierno)

Materia seca (g/kg) Nabo Vaca Lechera Leche Músculo Huevo Grano de cebada Maní

Pasto joven (tierno)

Tabla 1.1: Composición de algunos materiales vegetales y productos animales expresados como peso fresco (“tal cual”) o como materia seca

Agua Carbohidratos Lípidos Proteína Cenizas

McDonald, Edward, Greenhalgh y Morgan. Nutrición Animal, 5ta Edición

Cantidad

potencial de

nutrientes

No todo está

disponible para

los animales

(3)

CO2 NAD NADH+H H2O

½ O2

ADP+P

ATP

TRABAJO

SÍNTESIS

ALIMENTOS

· LECHE · FETO catabolismo oxidativo fosforilación oxidativa AGUA

HECES

A B C

AGUA

O2

CO2

CALOR

· TEJIDOS CORPORALES E F D G H I

CH4

CH4

BIOMOLÉCULAS 1 (COHN) BIOMOLÉCULAS 2 (COHN)

Hay pérdidas de nutrientes y energía en heces, orina, y pérdidas

adicionales de energía en gases de fermentación y calor

(4)

DIGESTIBILIDAD

ALIMENTO

HECES

DIGESTIBILIDAD 1: in vivo

(5)

10 kg MS/d

4 kg MS/d

ALIMENTO

HECES

DIGESTIBILIDAD 1: in vivo

Pérdidas fecales

10 kg MS/d – 4 kg MS/d = 6 kg MS /d

DIGESTIBILIDAD IN VIVO

10 kg MS/d – 4 kg MS/d

10 kg MS / d

= 0,6 (o 60 %)

Desaparecieron en el tubo digestivo

(6)

DIGESTIBILIDAD 3 : un suplemento

10 kg MS/d

4 kg MS/d

ALIMENTO

HECES

12 kg MS/d – 5 kg MS/d = 7 kg MS /d

DIGESTIBILIDAD IN VIVO SUPLEMENTO

2 kg MS/d – (5 kg MS/d – 4 kg MS/d)

2 kg MS / d

= 0,5 (o 50 %)

Desaparecieron en el tubo digestivo

Dieta Base

Dieta Base

Suplemento

2 kg MS/d

Suplemento

1 kg MS/d

Total

Total

12 kg MS/d

5 kg MS/d

ASUME ADITIVIDAD

à

no hay interacciones entre ambos alimentos

10 kg MS/d – 4 kg MS/d = 6 kg MS /d

(7)

Chapter 1 The animal and its food

4

Table 1.1 Composition of some plant and animal products expressed on a fresh basis and a dry matter basis

Water Carbohydrate Lipid Protein Ash

Fresh basis (g/kg) Turnips 910 70 2 11 7 Grass (young) 800 137 8 35 20 Barley grain 140 730 15 93 22 Groundnuts 60 201 449 268 22 Dairy cow 570 2 206 172 50 Milk 876 47 36 33 8 Muscle 720 6 44 215 15 Egg 667 8 100 118 107

Dry matter basis (g/kg)

Turnips 0 778 22 122 78 Grass (young) 0 685 40 175 100 Barley grain 0 849 17 108 26 Groundnuts 0 214 478 285 23 Dairy cow 0 5 479 400 116 Milk 0 379 290 266 65 Muscle 0 21 157 768 54 Egg 0 24 300 355 321

1.1

WATER

The water content of the animal body varies with age.The newborn animal contains 750–800 g/kg water but this falls to about 500 g/kg in the mature fat animal. It is vital to the life of the organism that the water content of the body be maintained: an animal will die more rapidly if deprived of water than if deprived of food. Water functions in the body as a solvent in which nutrients are transported about the body and in which waste products are excreted. Many of the chemical reactions brought about by enzymes take place in solution and involve hydrolysis. Because of the high specific heat of water, large changes in heat production can take place within the animal with very little alteration in body temperature. Water also has a high latent heat of evaporation, and its evaporation from the lungs and skin gives it a further role in the regulation of body temperature.

The animal obtains its water from three sources: drinking water, water present in its food, and metabolic water, this last being formed during metabolism by the oxidation of hydrogen-containing organic nutrients. The water content of foods is variable and can range from as little as 60 g/kg in concentrates to over 900 g/kg in some root crops. Be-cause of this great variation in water content, the composition of foods is often ex-pressed on a dry matter basis, which allows a more valid comparison of nutrient content. This is illustrated inTable 1.1, which lists a few examples of plant and animal products. The water content of growing plants is related to the stage of growth, being greater in younger plants than in older plants. In temperate climates the acquisition of drink-ing water is not usually a problem and animals are provided with a continuous supply. There is no evidence that under normal conditions an excess of drinking water is harmful, and animals normally drink what they require.

Peso fresco (g/kg) “tal cual”

Nabo Vaca Lechera Leche Músculo Huevo Grano de cebada Maní

Pasto joven (tierno)

Materia seca (g/kg) Nabo Vaca Lechera Leche Músculo Huevo Grano de cebada Maní

Pasto joven (tierno)

Tabla 1.1: Composición de algunos materiales vegetales y productos animales expresados como peso fresco (“tal cual”) o como materia seca

Agua Carbohidratos Lípidos Proteína Cenizas

¿?

¿Qué quiere decir proteína aquí?

¿Qué amino ácidos tiene cada una?

¿Cuántos escenciales hay por unidad

de proteína en cada una?

Proteína Bruta

Las proteínas tienen en promedio 160 g N/ kg (16 g %)

SI todo el N del alimento viniese de la proteína, cada 160 g de

N que midiésemos en un alimento, habría 1000 g de proteína.

La proteína bruta es: N total (g) / 0,16

o bien N total (g) * 6,25 (porque 1/ 0,16 = 6,25)

19,5 16 17,2 45,6 64 42,5 122,9 56,8

N total (g/kg MS)

(8)

N fecal

Heces

N fecal endógeno

(fecal metabólico)

1- Secreciones digestivas

2- Células descamadas

ALIMENTO

N (PB)

N indigestible del

alimento

3- Proteína microbiana

(9)

N fecal

Heces

N fecal endógeno

(fecal metabólico)

1- Secreciones digestivas

2- Células descamadas

ALIMENTO

N (PB)

N indigestible

del alimento

3- Proteína microbiana

Proteína aparentemente digestible:

N consumido – N heces

Digestibilidad aparente de la proteína:

N consumido – N heces

N consumido

(10)

N fecal (g/día)

consumo alimento (kg MS/día)

N indigestible del alimento

Secreciones digestivas

Células descamadas

Proteína microbiana

¿Secreciones digestivas?

¿Células descamadas?

Nitrógeno endógeno (fecal metabólico)

N endógeno

basal

N endógeno

específico

(11)

N fecal

Heces

N fecal endógeno

(fecal metabólico)

1- Secreciones

digestivas

2- Células

descamadas

ALIMENTO

N (PB)

N indigestible

del alimento

N ileal

(12)

N fecal

Heces

N fecal endógeno

(fecal metabólico)

ALIMENTO

N (PB)

N indigestible

del alimento

N ileal

N consumido – N ileal – N endógeno basal

N “verdaderamente”

digestible en íleon

E Basal

Figure

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Referencias

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