The growth of heifers depending on birth weight and the level of total immunoglobulins in the colostrum period

The development of Holstein calves obtained from sperm by various freezing methods, as well as depending on the level of immunoglobulins in the blood serum during the colostrum period (on the third day of life), depending on the live weight at birth, was studied. The work was carried out in the winter period at the “Agrofirma Zarya” in collaboration with Federal Research Center for Animal Husbandry named after Academy Member L.K. Ernst and the All-Russian Scientific and Research Institute of Animal Breeding under a scientific cooperation agreement.A total of 36 heifers were used in the experiment with different evaluation criteria: Depending on the use of sperm prepared in different ways: Group I (experimental) - heifers obtained from sexed semen (n = 18), Subgroup II (control) - heifers obtained from conventional semen (n = 18). Depending on birth weight: Group I - birth weight up to 35 kg (n = 11), Group II — 35–39 kg (n = 14), Group III - 40 kg and above (n = 11). Depending on the concentration IgG, they were divided into three groups: Group I (n = 6) — 6.0–6.5 g/dl, Group II (n = 14) — 6.6–7.5 g/dl, Group III (n = 16) — 7.6 g/dl and higher. It was found that the live weight of calves has a significant difference at p < 0.05, that is, heifers born from sperm harvested in the traditional way had 3.5 kg more live weight compared to heifers born from a sex-separated one. The discrepancy remains until 5 months of age, and at one year of age, on the contrary, calves born from sexed semen will have a birth weight greater by 9.1 kg than heifers born from conventional semen. Similar results at birth were noted in the analysis of daily weight gains (р < 0.01). It was revealed that calves with different live weight at birth had a significant difference before the age of 5 months, and after the age of 6 months, everything gradually smooths out.83% of calves had serum IgG levels above 6.6 g/dL. Only 16.7% of calves (n = 6) had relatively low serum IgG levels on day 3 of life. The heifer groups by IgG levels had a high level of significance (р < 0.01). Serum globulins did not have a significant effect on subsequent calf development.