Influence of the selection of parent pairs on the variability of cows’ milk productivity indicators

Abstract

Goal. To study the variability of milk productivity indicators in cows depending on different methods of selection of parent pairs. Methods. Zootechnical (milk productivity), retrospective analysis (zootechnical accounting data), biometric (average values and their errors, probability of research results), and dispersion analysis (power of factor influence). Results. During inline breeding, the first-borns of the Chif 1427381 line were characterized by the highest milk yield (6633 kg), and milk fat yield (238.0 kg). The firstborns of the S.T. Rokita 25280 line were the best in terms of fat content in milk (3.71%). Their probable (P<0.05 – 0.01) advantage for this indicator over individuals of the rest of the studied lines was 0.11 – 0.13%. During the third lactation, the highest indicators of milk yield (7825 kg), fat content in milk (3.61%), and milk fat yield (282.9 kg) were obtained by cows of the Starbak 352790 line. For interline breeding of the first-born cross of the lines Valiant 1650414 — Chif 1427381 according to milk yield (6903 kg), and yield of milk fat (249.1 kg), probably (P<0.05 – 0.01) outperformed the crossbred cows of lines R. Meximes 297414 — Chif 1427381, and Khaneve 1629391 — Starbak 352790 by 985 and 37.4, and by 1428 kg and 51.9 kg, respectively, and according to the output of milk fat, also individuals of the Haneve 1629391 — Chif 1427381 line cross by 34.8 kg. Compared to the animals of the other studied crosses, the firstborn of the Valiant 1650414 — Chif 1427381 line cross had an unreliable advantage in terms of these indicators. The highest content of fat in the milk (3.62%) was found in the first-born cross of Cavalier 1620273 — Chif 1427381 lines. During the third lactation, the highest milk yield (75.39 kg), fat content in milk (3.62%), and milk fat output (273.1 kg) were characterized by cows of the Elevaition 1491007 — Starbak 352790 line. The method of selecting parent pairs had a reliable (P<0.05) influence on milk yield (13.6%), and milk fat output (15.4%) of full-aged cows and did not have a likely influence on the indicators of milk productivity of first-borns. Conclusions. To improve economically useful indicators of cows of the Ukrainian black and white dairy breed, it is important to identify the best lines and outline the most promising ones for further improvement of the breed. The selection of parental pairs had the most significant effect on fertility and the amount of milk fat of adult cows, and the weakest — on the content of fat in milk during the third lactation.