Abstract
The article presents the results of research on the influence of paternal origin and belonging to a related group on the level of milk productivity of cows and the reproductive capacity of Jersey cows in the farm “Dan-Milk” of the Zhytomyr Region. The purpose of this study is to establish the influence of paternal origin and belonging to a related group on the level of milk productivity and reproductive capacity parameters of Jersey cows. The study established a substantial level of differentiation in the main economically useful features between groups of half-sisters by father. The best quantitative indicators of milk productivity were noted among the daughters of bulls DJ Jante 302761 (P<0.001) and Headline 114114336 (P<0.001), the worst indicators – among daughters of Karl 67037285. The highest indicators of fat and protein content in milk were noted in the cows bred from the bull Legal 61929249, the lowest – from the bull Karl 67037285. The influence of the origin of cows by father on the variability of milk yield and yield of milk fat and protein was 20.3–30.3% (up to P<0.001), the content of fat and protein in milk decreased to 13.2-20.0% (P<0.01 and P<0.05), and according to the reproductive capacity features – to 7.8-19.0% with an unreliable level of statistical significance. Prepotent as to milk yield are bulls Legal 61929249 and Headline 114114336, as to the content and yield of milk protein – Legal 61929249. Cows of the related group bred from the bull Observer 553236 are characterised by the highest milk yield and yield of milk fat and protein for both the first and best lactation, and cows of the related group bred from Surville 604694 are characterised by the worst yield. The influence of belonging to a related group on the studied features was several times lower (0.2-10.5%) compared to the influence of paternal origin. With an increase in the milk yield of cows over the first lactation, there is a stable and substantial decrease in the reproductive capacity coefficient due to the lengthening of the service period between the first and second calving. Such natural antagonism does not imply the goal of increasing the duration of the service period to obtain maximum milk yields for firstborn cows, since this will lead to a decrease in the yield of calves and render timely replenishment of the herd impossible. It is optimal to milk the firstborn up to 8 tonnes over 305 days of lactation while maintaining a satisfactory reproductive level
Highlights
Jersey cattle are described by high productive qualities and are the world's best dairy breed in terms of fat and protein content in milk
The highest indicators of fat and protein content in milk were noted in the cows bred from the bull Legal 61929249, the lowest – from the bull Karl 67037285
Apart from milk productivity, the authors of this study have investigated the features of reproductive capacity of the offspring of various breeding bulls as an essential aspect of the development of modern dairy cattle breeding
Summary
Jersey cattle are described by high productive qualities and are the world's best dairy breed in terms of fat and protein content in milk. This breed is quite common in England, New Zealand, Australia, Denmark, and several other countries [1,2,3]. The Jersey breed has been a source of valuable heredity, which determines exceptionally high levels of fat and protein content in milk and payment for feed with products, which depends on the correct choice of the breeding bull [4; 6]. The decisive role in the breeding process belongs precisely to breeding bulls, since they account for about 90% of the breeding effect [7]
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