Influence Of Different Factors On Lactation Performance Of Black-And-White And Holstein Cows

Abstract

Research objective:to study and analyze the increase of the indicators of lactation
performance of Black-and-White and Holstein cows depending on various factors.
Material and methods. The research included Black-and-White dairy herd of the agricultural
holding “Abdulla” and Holstein dairy herd of the agricultural holding “Khantemir” located in
the Akkurgan district of the Tashkent region of Uzbekistan. The lactation performance of
cows was studied and analyzed according to methods generally accepted in zootechnics.Each
experimental herd had identical conditions for feeding and animal welfare.
Results.Results of the study showed that the level of lactation performance depended on a
number of factors. Black-and-White cows ofIII lactation and over withservice period of 46-
90 days gave milk yield of 5473.5 kg, being higher compared to the indicators of milk yield
of cows with service periods up to 45 days and 91 days and over -499 and 881.5 kg,
respectively. Besides, Holsteins of III lactation and over achieved the highest rate of lactation
performance at their body weight of 721-750 kg, with milk yield of 8214.2 kg, which was
2216.7 kg more than that of cows weighing 600 kg.
Conclusion. The highest indicator of lactation performance was noted in Holsteins of winter
calving. The milk yield of cows of winter calving amounted for 7385.3 kg, and the indicators
of cows of spring, summer and autumn calving amounted for 400.9, 855.3 and 479.5 kg,
butterfat yield 14.7, 35.7 and 17.6 kg, and 4% milk yield 368, 1072.2 and 432 kg
respectively.