Analysis of the influence of the Norwegian Red bull-sires with different breeding value on milk productivity, health, exterior and reproductive traits of daughters

An analysis of the influence of breeding bulls of the Norwegian Red (NR) breeds with different breeding values (BV) on the milk productivity of daughters, their health, reproductive characteristics, udder characteristics, exterior, and indices of productive use. The study material was the data from the electronic catalog of breeding bulls of the NR breed as of April 4, 2023. The sample was formed from the data of only those breeders recommended for reproduction in 2023 by Geno SA. The animals were grouped according to the Total Merit Index (TMI). Breeding bulls with the highest TMI – 53-35 (n = 24) were assigned to the I group, to the II group – with an average TMI – 34-25 (n = 25), and to the III group – bulls with the lowest TMI – 24-10 (n = 22). As a result of the research, it was established that the most significant influence on the indices of productive use of daughters was observed in breeding bulls of the NR breed of the I group (High production index (HPI) – 118.13 % (Р < 0.001), Grazing index (GI) – 110.88 % (Р < 0.05)). According to the TMI index, bulls of the I and II groups prevailed over the sires of the III group, according to their improving effect, on such signs of milk productivity of daughters as milk yield (Р < 0.01), amount of milk fat (Р < 0.05; Р < 0.01) and protein (Р < 0.01; Р < 0.001) and milk productivity index (Р < 0.001 and Р < 0.01) in daughter cows. The greatest improving effect on the udder health of the daughter cows was observed in breeding bulls of the NR breed with TMI 53-35. Bull-sires of groups I and II reduced the number of somatic cells count in the milk of daughter cows by 15.58 and 9.16 %, and bulls of III – only by 3.82 %. Breeder bulls of groups I and III increased milking speed in daughter cows by 4.25 and 1.68 %, and breeders of group II decreased it by 1.96 %. However, the difference was significant only between groups I and II (P < 0.05). Studied breeding sires increased daughters' stature (height) in all groups. Group I sires had the most significant influence on daughters' stature – 114.88, and III group sires had the most minor influence – 102.00. However, the difference was significant between the I and II and I and III groups (Р < 0.05; Р < 0.001). Bull-sires of the I group of the NR breed increased the feet and legs index in daughter cows, as well as the foot angle by 7.58 and 7.38 %, II breeders by 3.48 and 2.48 %, and bulls III reduced these traits in daughters by 0.41 and 0.14 %. The difference between the I and III groups was significant (P < 0.05). Breeder bulls of the NR breed with TMI 53–35 were leaders in improving the udder index of daughters, as well as in reducing its udder depth, strengthening the fore udder attachment, increasing the rear udder width and rear udder height. Therefore, the most significant impact on most of the studied traits was observed in breeding bulls of the NR breed with the highest BV – TMI 53-35. The influence of sires with TMI 53-35 and 34-25 on daughters' milk production was almost the same and improving. However, in terms of the effect on the reproductive characteristics of daughter cows, no significant difference was found between all experimental groups of breeding bulls.