The paper presents results of assessing black-and-white bulls by the quality of the offspring with application of different methods. The evaluation of bulls was carried out with application of the “daughter-mother” method in the conditions of Volzhsky Research Institute of Hydraulic Engineering and Land Reclamation. The valuation showed that the bulls Aist 7 and Muscat 8 increased milk yield of daughters, in comparison with mothers, by 951 and 486 kg, or by 26.7 and 12.9%. The rest of the servicing bulls reduced milk yield of the offspring by 46 - 1019 kg (1.1 - 24.7%). When assessing the bulls using the “daughterpeer” method, the highest milk productivity was shown by the descendants of Sazan 25 and Aist 7 of Vis Back Ideal line, which surpassed their peers in milk yield by 273 and 419 kg, or by 3.8 and 5.7%, respectively. The producers Snop 57 (his 17 daughters had average milk yield of 4224 kg for the first lactation with milk fat of 3.80%) and Muscat 8 (with an average milk yield of daughters of 4254 kg , milk fat - 3.83%) are also of significant value for the breeding work of this farm. According to the assessment results, the producer Aist 7 was assigned to the breeding category of A1 of milk yield improvers. Bulls Sazan 25 and Muscat 8 are also rated as daughters’ milk yield improvers and are categorized as A2 and A3. All bulls evaluated by comparing daughters to the breed standards are improvers of daughters’ milk yield (+ 454-1860 kg).
Effects of maternal age and stress on offspring quality in a viviparous fly