Results of studies on the correlation between ribeye area and backfat thickness with live weight in kazakh white-headed and auliekol bull calves

Abstract

Background and Aim. In the context of the growing demand for high-quality beef, the development of beef cattle breeding in Kazakhstan is becoming increasingly important. Domestic specialized beef breeds, the Kazakh White Headed and Auliekol, are characterized by high adaptability to harsh climatic conditions, the ability for intensive fattening, and the accumulation of energy reserves. The realization of their genetic potential, especially under adequate nutrition at an early age, has a positive effect on productivity and meat quality. The aim of this study was to determine the relationship between ribeye muscle area and subcutaneous fat thickness with live weight in bulls of these breeds, and to identify animals with a genetically determined combination of high live weight and favorable product quality traits.

Materials and Methods. The objects of the study were Kazakh White-Headed and Auliekol bulls aged 8 to 12 months that underwent performance testing at the base farms of Daŭren Farm (Abai Region) and Dievskaya Agrofirm LLP (Kostanay Region). Indicators of live weight, average daily gain, ribeye muscle area, and subcutaneous fat thickness were studied. The latter two parameters were measured using ultrasonography, followed by statistical processing of the obtained data.

Results. The live weight of Auliekol bulls exceeded the breed standard of Class I by an average of 38 kg (12.2%), whereas Kazakh White-Headed bulls corresponded to the elite record class. The Kazakh White-Headed breed was characterized by greater early maturity: with a feed conversion of 6.9 feed units per 1 kg of weight gain, the average daily gain reached 1,475 g. It was established that, in the Kazakh White-Headed breed, as live weight increased, both ribeye muscle area and subcutaneous fat thickness increased proportionally, whereas in the Auliekol breed, the increase in ribeye muscle area was less pronounced.

Conclusion. Breed-specific, biologically determined differences in the intensity and duration of growth of bulls were identified. These differences should be taken into account in breeding programs and in the formation of productive groups of beef cattle.