Аңдатпа
Currently, dairy cattle breeding places particular emphasis on studying the genetic characteristics of breeds, their phylogeny and breed formation, similarities and differences, as well as identifying genetic anomalies and their origin. This study presents a comparative analysis of lactation patterns in Holstein and Alatau cows depending on their line affiliation. The research was conducted at the private farm “Karimov” in the Koksu district of the Zhetysu region. The objects of the study were cows of different breeds and genealogical lines (genotypes): Wis Bek Ideal 1013415 and Reflection Sovereign 198998 (Holstein breed), as well as the related groups Meridian 90827 and Concentrate 106157 (Alatau breed). A linear (genotypic) and age-related (phenotypic) dependence of productive traits was established. First-calving cows of the Meridian related group exceeded those of the Concentrate group in milk yield by 1,038 kg (P<0.001); in the second lactation by 613 kg (P<0.001); and in the third and subsequent lactations by 714 kg (P<0.001). In terms of milk fat content, cows of the Concentrate group showed slightly higher values than those of the Meridian group; on average, the difference amounted to 0.04% (P<0.05). No significant differences were found in milk protein content. Mature cows were characterized by the highest uniformity of lactation yield (Cv = 4.2–8.1%). Cows of the Wis Bek Ideal line consistently outperformed those of the Reflection Sovereign line in milk yield across all age groups: by 394 kg in the first lactation (P<0.001), by 1,264 kg in the second (P<0.001), and by 1,092 kg in the third and subsequent lactations (P<0.001). On average, milk yield across lactations was 530 kg higher (P<0.001) in the Wis Bek Ideal line. Analysis of monthly milk yield dynamics showed that the lactation curves of the Wis Bek Ideal line and the Meridian group correspond to the first type (high and stable), whereas those of the Reflection Sovereign line and the Concentrate group correspond to the second type (high but unstable).