RELATIONSHIP OF MILK PRODUCTIVITY OF COWS WITH LIVE WEIGHT AND AGE AT THE FIRST INSEMINATION
Authors: Ilyashenko G. D. 
Published: November 2018

The efficiency of the use of cattle of one or another breed is determined both by the level of milk productivity and the ability of the cattle to reproduce. At the same time, the future reproductive capacity, milk yield and duration of economic use to a large extent depends on the live weight and age when heifers insemination.

The purpose of research. Study the effect of live weight and age at the first insemination on the milk productivity cows of Ukrainian red dairy breed.

Methods. The research was carried out in the breeding plant of the state enterprise "Elite" of the Kirovograd state agricultural research station of NAAS on 697 cows of Ukrainian red dairy breeds, which were found during 2004–2014. Milk productivity of cows and their live weight and age at the first insemination were investigated according to the materials of the primary zootechnical and pedigree records. The degree of connection of live weight and age at the first insemination with milk productivity was estimated by correlation analysis. One-factor dispersion analysis determined the level of influence of the age of the first insemination and live weight on the productivity of cows. The calculations were made using methods of mathematical statistics using the software package "STATISTICA-6.1".

Results of research. By the analysis of milk production on experimental cows, determined, that its level depends on the live weight of animals at the first insemination. Therefore, cows with live weight at the first insemination was 420–439 kg, dominated by mercy unique live weight of 380 kg in the first lactation at 244 kg (6242 vs 5998 kg), td = 1,96 for the third – 1069 kg (7465 vs 6396 kg), td = 2,37 by best lactation 498 kg (7916 vs 7418 kg), td = 2,03, significance level for all lactation (P < 0,05). To the milk fat, accordingly, the predominance was 13.2 kg (260,2 vs 247,0 kg), 22,9 (309,5 vs 286,6 kg) and 21,0 kg (325,1 vs 304,1 kg), the difference is close to the true values. The peers with a live weight of 400–419 kg and 440 kg and more also yielded in the first milk yield. The difference the milk I, III and the best lactation was 72 kg, 219 kg and 91 161 kg, 674, 589 kg for milk fat yield 5 kg, 10.3, 6.1 kg and 11.5 kg, 28.8, 19.5 kg, respectively. Due to the lesser number of animals, the vast majority of values did not reach a reliable level.

Studies of milk productivity of cows, depending on the age of the first insemination, showed that its cow was the highest, which were counted at the age of 455 days. The lowest rates of dairy productivity were the animals that were fertilized at the age of 606 or more days.

Correlation analysis found the highly reliable of feedback age insemination of cows milk yield in the first three lactation (-0,25 ... -0,37). Similar patterns of feedback for somewhat lower correlation coefficients are noted with the release of milk fat (-0,23 ... -0,33). Coherence of live weight at the I insemination and follow-on milk production was significantly lower (compared with age insemination) in absolute value, for only a certain level of first lactation milk yield and milk fat yield (P < 0,05).

The significant influence of the investigated factors on milk yield of cows is established. Thus, by milk yield and milk fat and protein for 305 days of lactation cows power of influence age of first insemination exceeded 50%, the fat and protein in milk index of potency is 32 and 30% by high-confidence values for milk yield and yield of milk protein and fat . Somewhat lower than 20 to 33%, the effect of live weight on the first insemination was shown on the performance of cows.

Сonclusion. The heifers of the Ukrainian Red dairy breed in conditions of the Central region of Ukraine advisable to fertilize at the age of 455 days, or 14,5–15 months, when they reach the living weight of 420–439 kg.

The revealed feedback of the inseminative age and milk productivity can be explained by more intensive growth, better development and economic rapidity of the previously diced heifers and its should lead to intensive rearing of young animals.

Determined, that the force of age-old influence of the first insemination on the lactic productivity of the cows exceeds 50%, the live weight reaches from 20 to 33%. Discovered tendency also confirms the expediency of intensive growth of repair heifers.