FACTORS AFFECTING COW REPRODUCTION
FACTORS AFFECTING COW REPRODUCTION
Anna Krovikova
Candidate of Biological Sciences, Associate Professor Federal State Budgetary Educational Institution of Higher Education "Moscow State Academy of Veterinary Medicine and Biotechnology - MVA named after K. I. Skryabin,
Russia, Moscow
The economic efficiency of dairy cattle breeding directly depends on the rate of reproduction of livestock. From each cow, under optimal conditions, you can get a calf per year. To do this, it is necessary that the cows in the herd become pregnant within 80-85 days after calving.
Reproduction of animals is one of the urgent problems of dairy cattle breeding. To improve the situation, normal conditions for keeping and feeding livestock are necessary, as well as proper organization of reproduction, first of all, timely and scientifically based measures to prepare heifers for insemination.
Reproductive and productive abilities depend not only on the age of heifers, but also on their body weight during the period of fruitful insemination. The first insemination of black-and-white Holstein cattle is optimally carried out at the age of 18 months at 360 kg of live weight. With earlier terms and lower weight, calves are born small, and milk yield for the first lactation does not reach the genetic potential. Nevertheless, in production conditions, the bulk of heifers are inseminated up to 18 months of age with a live weight of 300-330 kg.
Such important indicators as the yield of calves per 100 cows and milk productivity also depend on the timing of insemination after calving. Most recommendations note that insemination of cows in the first month after calving gives the greatest effect. However, when analyzing the real indicators of animal reproduction, it is not difficult to make sure that fertilization occurs in most cases not in the first, but in the second hunt. In this regard, V. Masalov conducted research to identify the optimal timing of insemination of cows after calving.
Low fertilization of cows in the first month can be explained not only by poor conditions of maintenance and feeding, but also by the fact that the involution of their genitals ends no earlier than 40-60 days after calving. At this time, the energy consumption of the diet for lactation is still insignificant, and by 2-3 months they will increase sharply. Proper feeding and maintenance of cows during pregnancy and after calving will ensure their fruitful insemination in the first months after childbirth, which will increase the yield of calves and increase milk production.
V. Masalov revealed the dependence of reproduction indicators on the level of productivity and age of cows. The highest fertilization was observed during the periods of the third and fourth lactation, and the lowest — at the age of the first and sixth lactation. It is possible that with the improvement of housing and feeding conditions, the fertilization of cows will increase with age. With increasing productivity, fertilization decreases. The inverse relationship between these indicators can be explained by "competition" in the distribution of feed energy. It follows from this that such physiological processes as fertilization and milk productivity, interconnected with each other, are also influenced by feeding conditions.
The results of V. Masalov's research explain the relationship of cow milk yield with the duration of the service period, studied during the third lactation. From the data obtained, it follows that the lowest milk yield was in the group of cows fertilized in the first hunt after calving. However, this ultimately increases both the yield of calves and the level of productivity of cows on average for all lactation. Thus, the production indicators of farms in the Orel region indicate that with the increase in the yield of calves, the milk yield per feed cow also increases.
V. Masalov's research revealed the dependence of fertilization on the season of the year. The lowest indicator falls on the winter-stall period of maintenance, and the highest — on the summer-pasture period. At this time, the great activity of the reproductive functions of heifers and cows is due to proper nutrition during grazing, solar radiation, exercise, as well as a high content of phytohormones in the grass.
Calving is distributed accordingly. The main number of them falls on the stall period. The current seasonality can be explained by the fact that with poor preparation for calving and inadequate nutrition after it, most cows that calved during the winter-warm period are fertilized when they are transferred to foot food.
From the materials conducted by V. Masalov, it follows that in order to organize year-round calving and fertilization of cows, it is necessary to improve the structure of the feed base, improve the quality of harvested feed and the usefulness of rations. V. Masalov recommends providing year-round calving (8-12% of dairy cows per month).
One of the crucial moments of dairy cattle breeding technology is the dry period (Masalov V.N., 2007). It is at this time that the foundations are laid for the well-being of the clinical condition of the mother and offspring, a favorable outcome of calving and the postpartum period, the course of lactation. The state of the cow before calving has a great importance on the intensity of reproduction. It was found that cows of lower average fatness during the deadwood period had a service period of 193 days, and cows of average fatness were fertilized after calving after 164 days, that is, 1 month earlier. The correlation coefficient between the studied indicators is equal to r = 0.20-0.29.
According to some scientists, the duration of the dry period largely depends on the qualifications of the milkmaid. In the studies of Yulmetyeva Yu.R. (2011), the duration of the dry period in the studied groups ranged from 53-67 days. The average duration of the dry period in all breeds decreased from the initial to the next generations, in Dutch and German breeds to the second generation, in Danish to the third generation. That is, lower values of the average duration of the dry period in Dutch and German cows were observed in the second, and in the Danish in the third generation, which turned out to be 12 and 8 days less in comparison with the original cows of the same breeds. The variability of the dry-hardy period in cows of different groups varies: from 26.2% in imported Dutch to 39.7% in the first generation of Danish heifers, which requires a more attentive attitude to the organization of the launch of cows.
In the Orel region, according to zootechnical and breeding records, the reproductive ability of Holstein cows of different bloodlines was studied in comparison with the original animals of the black-and-white breed. The data obtained show that the crossing of cattle allowed to increase the milk productivity of crossbreeds compared with purebred animals. With an increase in the proportion of blood of the Holstein breed, a decrease in reproductive ability was observed in the crossbreeds. This is evidenced by data on the duration of the service period, MOS and fertilization of animals after calving (Rodina N. D., 2005, 2011).
Violation of the reproductive system of cattle currently represents the main obstacle to increasing milk yields and economic efficiency of animal husbandry (Bakai A.V., Skripnichenko G.G., Bakai F.R., 2005; Lapteva N.N., Gavrikov A.M., 2013). To achieve maximum milk productivity, it is necessary to constantly maintain a high level of reproduction of the herd. Hormonal synchronization program is widely used in all countries with developed animal husbandry to stimulate and synchronize hunting with subsequent insemination. At the same time, the fertilization of cows increases by 93.5% (Perepelyuk A., Shishkin O., 2011).
The main reasons for culling cows on the farm are low productivity, gynecological diseases, infertility, leukemia, injuries, udder diseases, digestive diseases. According to the majority of domestic studies, highly productive animals should be used for at least five to six lactations. The optimal duration of the interbody period is 365 days. The interbody period can range from 340-405 days, it depends on the size of the service period. An increase in the interbody period entails a reduction in the yield of calves. The interbody period is one of the most important indicators determining the efficiency of the dairy herd. The cow's ability to become pregnant in time depends on its ability to show signs of hunting and fertilization.
References:
- Bakai, A.V. Morbidity of reproductive organs in cows depending on belonging to different genealogical groups, lines and branches / Bakai A.V., Skripnichenko G.G., Bakai F.R. // International scientific and practical conference, "Achievements of zootechnical science and practice – the basis for the development of livestock production" / Volgograd. State. S-x. acad. Volgograd. 2005. – pp. 101-104.
- Lapteva, N.N. features of the reproductive function of purebred and crossbred cows / Lapteva N.N., Gavrikov A.M. // Zootechnia. - No. 10. – 2013. – pp.31-32.
- Masalov, V. V. Ways to increase the reproductive function of cows and heifers / Masalov V. N., Enin Yu. M., Sinitsyn A. N., Kozlov A. S. // Vestnik Orel Gau. – 2007. - No. 1. – pp. 23-24.
- Perepelyuk, A. Effective methods of herd reproduction control / Perepelyuk A., Shishkin O. // Animal Husbandry of Russia.- 2011. - No.11. from 44-45.