MATRIZ DE GESTIÓN DEL TALENTO HUMANO

attributes of Broiler Meat

1 1 2 1

AKINWUMI, A.O., ODUNSI, A.A., OMOJOLA, A. B AND ADEMOLA, S.G.

1_{Department of Animal Nutrition and Biotechnology, Ladoke Akintola University of Technology,}

Ogbomoso, Nigeria.

2_{Meat Science Laboratory, Department Animal Science, University of Ibadan, Ibadan, Nigeria.}

safe concentrations in the tissue of the animal or the interval from the time an animal is removed from medication until the permitted time of slaughter. The purpose of withdrawal periods is to ensure that residues are at acceptable levels, taking into account the method of administration, the rate of absorption, metabolism and excretion of the drug. Adherence to withdrawal time maybe considered burdensome,

inconvenient and expensive (Sundlorf, 1989; Akinwumi et al., 2013). Also improper maintenance of

treatment records, or failure to identify treated animals adequately, and attempting to salvage terminally ill animals for slaughter purposes that recently have been treated with antibacterial drugs can lead to

abbreviated withdrawal periods. Akinwumi et al., (2013) stated that most farmers (91%) in Nigeria

claimed to be aware of the withdrawal period but their frequencies of observing (54%) it showed that some farmers are not always conscious of it and this could be counter-productive to the consuming public.

Apart from the reports on effect of antibiotics on resistance and existence of the residue, not much is known about the potential influence on meat quality of veterinary drugs. Overall quality traits of meat comprise hygienic aspects in relation to safety and toxicology (presence of undesirable microorganisms or residues such as antibiotics, hormones or chemical contaminants), nutritional value and technological

and sensory attributes (Cavani et al., 2009). As reported by Aliu (2004) the palatability, aroma and

quality of meat could also be affected by drug residues. However, Hughes and Heritage (2004) reported direct beneficial effects on the product quality, such as decreased fat and increased protein in the meat, and indirect benefits such as a reduction in the amount of feed needed, and therefore a reduction in the amount of waste.

The study determined the effect of withdrawal period of antibiotic (Tetracin®)on physico-chemical properties and organoleptic properties of broiler meat.

Material and Methods

A 6- week experiment was conducted with 150, 2 week old broilers chicks that were randomly assigned to graded levels of veterinary antibiotic Tetracin®. Tetracin® (feed grade antibiotics) drug was bought at a reliable veterinary store and administered through Conventional broiler starter (CP – 23%, ME 3000kcal/kg) and broiler finisher (CP – 20%, ME 2900kcal/kg) diets at different inclusion levels.The withdrawal period (the feed grade antibiotic was stopped for selected birds) was observed for 15 days, 7 days and 0 day prior to slaughtering. Fifteen days was the actual label withdrawal period for Tetracin®. Five birds for each group were slaughtered by severing the jungular veins and carotid arteries, oesophagus and trachea, without severing the spinal cord.

Following slaughtering, Physico-chemical parameters of the meat from these birds were analyzed and compared. WHC of the samples were determined by the filter press method as modified by Tsai and Ockerman (1981). Cooking loss and thermal loss were calculated as the difference in percentage terms between pre - and post-cooking weight and length respectively (Honickel, 1998). Warner Brazter shear force (WBSF) determination was performed on the boiled meat samples using the modified Warner Brazter Shear Force procedure (Bouton and Harris, 1978). Proximate analysis was use to determine the chemical attributes of the broiler meat according to A.O.A.C (1999). The organoleptic properties was conducted using a 10 member trained panelists according to the procedures of AMSA (1995). The trained panelists evaluated the samples for colour, flavour, juiciness, tenderness and general acceptability. The assessment was based on a 9 point hedonic scale.

All data obtained were processed and subjected to analysis of variance (ANOVA) using statistical analysis software (SAS, 1999). Significantly different means were separated using Duncan's multiple Range (DMR) test.

Results

There were significant (P<0.05) differences observed in cooking loss, WHC, drip loss and chilling loss of the broiler chicken (Table 1). At 15 days withdrawal period, a lower (P<0.05) cooking loss (18.42%) was observed compared to values obtained for 0 day (24.45%) and 7 days (21.34%) withdrawal periods. The WHC for the meat samples expectedly showed similar trend with the cooking loss but in an inverse way. The highest (P<0.05) value was obtained in 15days withdrawal period with 81.60% and the least in 0day (74.82%). Both drip loss and chilling loss showed a progressive decrease with an increase in the days of withdrawal period and the least values were found in the 15 days withdrawal period. Shear force showed no significant differences (P>0.05) as the days of withdrawal period increased. The withdrawal periods of the antibiotics had no significant (P>0.05) effect on the chemical composition of the meat (Table 1). The CP, EE and ash numerically decreased as the withdrawal periods increased. When withdrawal periods are not observed (0 day), the highest CP and EE were recorded as 21.32% and 7.03% respectively. Significant (P<0.05) difference was also observed in the moisture content as the lowest was found in day0 of the withdrawal period.

The sensory evaluation of the panelist is as shown in Table 2. The withdrawal period had no effect (P>0.05) on the colour, flavor and general acceptability of the broiler meat. The tenderness and the

®

Table 1. Effect of withdrawal periods of Tetracin on physical and chemical properties of broiler

chickens

Withdrawal periods

Parameters (%) 0day 7days 15days SEM

Physical properties Thermal loss 12.34 11.89 10.57 2.43 Cooking loss 24.45a _21.34b _18.42c _1.34 WHC 74.82c _78.06b _81.60a _2.34 Drip loss 3.66a 3.47b 3.21c 0.23 Chilling loss 5.79a _4.34b _3.42c _0.54 Shear force 2.24 2.29 2.14 0.07 Chemical properties Crude protein 21.32 19.51 19.31 1.82 Ether Extract 7.03 5.96 6.00 0.34 Ash 1.13 1.19 1.08 0.04 Moisture content 70.15b 72.37a 73.23a 0.42

a,b,c: _{Means along the same row with different superscripts differ significantly (P<0.05)}

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Table 2. Effect of withdrawal periods of Tetracin on organoleptic properties of broiler chickens

Withdrawal periods

Parameters (%) 0day 7days 15days SEM

Colour 6.42 6.34 6.53 0.42

Flavour 5.37 5.52 5.68 0.25

Juiciness 6.62b 6.67b 7.16a 0.33

Tenderness 6.34a 5.83ab 5.00c 0.21

General Acceptability 7.42 7.32 7.51 0.53

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juiciness of the meat samples were however significantly (P<0.05) influenced significantly (P<0.05) by the withdrawal periods. An increase (P<0.05) in value was observed in the values for juiciness while a decrease (P<0.05) was observed in the tenderness as the days of withdrawal increased.

Discussion

The ability of fresh meat to retain moisture is arguably one of the most important quality characteristics of raw products. Product weight losses due to purge loss entail the loss of a significant

amount of nutrients (Melody et al.,2004). Lower WHC indicated losses in the nutritive value through

exudates that are released and result in drier and tougher meat (Dabes, 2001; Akinwumi, 2006). It was however observed that the physical properties (especially cooking loss and the WHC) improved when withdrawal periods were observed at 15days.

This study corroborated the earlier findings of Hughes and Heritage (2004) that antibiotics in animal feeds result in a better meat quality with a reduced fat and increased protein contents. Higher values for protein was reported when withdrawal periods was not observed, it was also puzzling to observe a decline in the fat contents as the withdrawal periods of the antibiotic increased.

No influence was observed by the panelist on the withdrawal periods of the general acceptability of the broiler meat. It was rated as moderately liked. This means with or without observation of withdrawal period of antibiotic, consumer will still like the meat and will be willing to consume it. This was in agreement with Ristic (2003), who reported that production system did not affect overall

sensory attributes. Omojola et al. (2012) also stated that meat acceptability was mostly based on

attractive colour, desirable flavour in the first instance, and on the combined effects of tenderness, juiciness and texture of a particular meat as evaluated by an individual consumer. However, the juiciness increased while the tenderness reduced with the increase in days of withdrawal period, this could be attributed to the improved values in WHC and cooking loss. But all this was to no avail with

the overall panelists rating of the meat. This result corroborated Aberle et al.,(2001) who reported that

experience of eating meat did not cause separate impressions of tenderness, juiciness, and flavour, but rather an overall impression.

Conclusively, this study has revealed a better cooking loss and WHC with no adverse effect on proximate composition of meat when withdrawal period of antibiotic was observed. The overall acceptability of the meat showed that with or without observation of withdrawal period of antibiotic, consumer will be willing to consume it.

References

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Introduction

Citrus sinensis originated in Asia, mainly South-east, where many species can be found growing in the wild and belongs to the family Rutacea. The world production of citrus is greater than that of any other fruit crops (Okwu and Emenike, 2007). Citrus is the world number one fruit crop in terms of production

Keywords: Cybopogon flexuosus, Xylopia aethiopica, Ocimum gratissimum, Cybopogon citratus, Pycathus angonensis, Penicillium rot, Essential oil, Citrus.

Abstract

Increasing public concern over the level of pesticide residues in food, especially fresh produce, has built up adequate pressure for scientists to look for less hazardous and environmentally safer compounds for controlling post-harvest diseases. This study, therefore identify the essential oils with antifungal activity from some Nigerian plants and their potential application as antifungal compounds against Penicillium digitatum infected Citrus sinensis fruit in an in-vivo experiment. The Cybopogon flexuosus oil exhibited significantly (P < 0.05) highest antifungal activity of 100% mycelial inhibition at 1200 part per million (ppm). Similar trends were observed on the effect of essential oil of Cybopogon flexuosus on spore germination, germ tube elongation and weight of mycelial of P. digitatum. This was followed by that of Xylopia aethiopica which also gave significantly (P < 0.05) high degree of mycelial and spore germination inhibition. The essential oil of Pycathus angonensis did not show any inhibitory effect on mycelial growth of P. digitatum even at the highest concentration. While the essential oil of Ocimum gratissimum and Cybopogon citrutus respectively gave the significantly (P < 0.05) least degree of mycelial and spore germination inhibition. Spore germination and germ tube elongation of the pathogens in potato dextrose agar were significantly (P < 0.05) decreased with increase in the concentration of Cybopogon flexuosus oil. The same concentration of this oil reduced the percentage of decayed Citrus sinensis. This result showed that the essential oil of C.flexuosus gave the significantly (P < 0.05) least fruit rot of 21.91% at the 21 days after incubation (DAI) and concentration of 1200ppm. The result showed that the essential oil of C. flexuosus at the highest concentration of 1200ppm gave the significantly (P < 0.05) least fruit rot of 21.91% at the 21 DAI compared with the artificial inoculated fruit with no treatment that gave significantly (P < 0.05) complete fruit rot of 100%. In addition, when unwounded naturally infected Citrus sinensis fruits were treated with different concentrations of essential oil of C.flexuosus only 8.92% fruit rot was recorded at the concentration of 1200ppm and 21 DAI. The fruit rot in unwounded and naturally infected Citrus sinensis was significantly (P < 0.05) lower than the wounded and artificially inoculated Citrus sinensis fruits. The result showed that Citrus sinensis fruits were better protected against fruit rot, whether artificial or naturally inoculated over a period of 21 DAI using essential oil of Cybopogon flexuosus. Whereas, the significantly (P < 0.05) highest fruits rots of 70.14% was observed at 21 DAI when the fruits were not wounded and 100% fruit rot in the artificially inoculated fruit. The inhibitory effect of the essential oil of C.flexuosus significantly (P < 0.05) increased with increase in concentrations. Application of essential oils for postharvest disease control of fresh produce, as a novel emerging alternative to hazardous anti-fungal treatments will allow a safer and environmentally more acceptable management of postharvest diseases.