The influence of genotype, year and age of first calving of Black-and-White primiparas on the results of conformation assessment and milk performance
2003
Stanek, P. | Litwinczuk, Z. | Zelezik, M. | Kowalski, P. (Akademia Rolnicza, Lublin (Poland). Katedra Hodowli Bydla)
The surveys were carried out to evaluate the conformation and milk performance of 227 primiparous BW with varying proportion of HF upgrading in the Lublin region. There were cows that calved between 1995 and 2000 and completed their first lactation. Conformation was evaluated in a 100-point scale. The performance evaluation included analysis of milk, fat and protein yield for lactation and milking day as well as protein and fat content and protein-fat proportion in milk. Average daily milk, fat and protein yields were also analysed. Throughout the analysed period, considerable genetic progress was observed as far as milk performance and body conformation were concerned. A significant influence was contributed by HF genes in the improvement of conformation traits in the analysed cows. A greater proportion of Holstein Friesian was found in the genotype of the local cattle upgraded in caliber, type and udder structure. No differences were found in leg and hoof structure. The increase in proportion of HF gene caused a significant increase in milk, fat and protein yield for lactation day and for full lactation, simultaneously affecting the elongation of the lactation period from 321 to 372 days. The most favourable relation between protein and fat was found in cows of highest HF upgrading (greater or equal 75 percent). The age at first calving did not influence the subsequent performance of the analysed cows. The best conformation was obtained for calving primiparas between 24 and 28 months
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