نوع مقاله : مقاله پژوهشی
نویسندگان
1 عضو هیئت علمی، بخش تحقیقات علوم دامی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان گیلان، سازمان تحقیقات، آموزش و ترویج کشاورزی،
2 بخش علوم دامی، دانشکده علوم و مهندسی کشاورزی، پردیس کشاورزی و منابع طبیعی، دانشگاه رازی، کرمانشاه، ایران
3 هیئت علمی گروه علوم دامی، دانشگاه آزاد اسلامی واحد گلپایگان
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Castration is one of the management activities practiced worldwide in order to reduce aggressive behaviour, sexual activity and to facilitate management ease. Numerous studies have been conducted comparing production efficiencies and carcass traits of intact and castrated beef cattle and sheep. It has been agreed generally that castration causes less growth efficiency and produces carcasses with higher fat contents which results in increased proportion of saturated fatty acids. However, effects of castration on mentioned parameters in goats has been less investigated, despite the fact that goats genetically deposit less fat in their muscles with a more favorable fatty acid composition compared with other ruminants. Therefore, this research was conducted to evaluate carcass and meat quality attributes in Markhoz breed and the effects of castration on performance, meat quality attributes and fatty acid composition of triceps brachii muscle and omental fat.
Materials and Methods: Sixteen male Morkhoz kids (13.2±1.6 kg live body weight, 3 months old) were used to evaluate the effects of castration on growth performance, meat quality attributes and fatty acid composition of muscle and omental fat based on a completely randomized design with 2 treatments and 8 replicates. Kids were castrated using ring castration in the respective treatment one week before the beginning of the experimental period. During 119 days of feeding experimental diet (formulated to meet NRC recommendations for small ruminants), growth performance of kids was recorded individually. Then, all kids were slaughtered and enough samples of triceps brachii muscle and omental fat were collected from each carcass, vacuum-packed and frozen at −20°C until subsequent determination of quality attributes including shear force, cooking loss, colour, proximate composition and fatty acids profile. The value of pH24, percentages of drip loss and water holding capacity were determined immediately on the day after slaughtering.
Results: Kids growth performance parameters, including average daily feed intake, average daily weight gain, and feed efficiency declined significantly in response to castration (P<0.05). However, empty body weight (% of live weight), cold carcass percentage and maximum width and depth of longissimus thoracis muscle were similar between treatments. With the exception of fat percentage of triceps brachii muscle, which increased significantly by castration (P<0.05), other measured quality attributes of mentioned muscle, including pH24, drip loss, water holding capacity and the percentages of moisture, protein and ash, were not affected by castration. Castration had no significant effect on fatty acid composition of intramuscular fat in the triceps brachii muscle; but, in abdominal fat tissue the percentages of 17:0 and 18:3 n3 fatty acids and the cumulative amount of odd chain fatty acids decreased and the n6/n3 ratio increased in response to kids castration (P<0.05).
Conclusion: In conclusion, results showed that Morkhoz kids castration at weaning, in addition to diminution of growth performance and feed efficiency, with respect to consumers’ health, will also reduce the nutritional quality of meat and internal fat tissue.
کلیدواژهها [English]
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