Evaluation of the herd reproduction program with sexed seed in a large agricultural enterprise

. For diary herding, milk production is one of the determining factors of effective actions. That is why it’s very important to get a high percentage of heifers into a processing of herd reproducing, which became possible after introduction of sexed seed – sperm, which cells are divided concerning the sex. Using of sexed seed allows us to repair the herd more quickly, and also to increase the realization volume of heifers by breed enterprises, which very good influence on their profitability. Provided of researching analyses showed us, that using the seed divided by sex into a large agricultural enterprise, the fertility rate is lower on 5-8%, than we will use the traditional seed, and female calves are much higher.


Introduction
Nowadays one of innovative methods of cattle reproduction is using of genetically material, separated by sex.[1,2].The leader of producing and realization of sexed seed is the USA company named CRI.The company gets the sexed seed from the best milkbreeding bulls.The seed includes at least 90% spermatozoids, which carry female sex chromosomes [3].Using of seed, separated by sex, gives an opportunity to get 80% heifers from all the calves received, which in turn, allows to renew the herd with the first heifers much quicker and if necessary to increase the herd annually [4,7].With the increase in the intensification of dairy cattle industry, accompanied by decrease of prolongation of farm cows using, zoo-veterinary specialists has an aim as to get more quantity of female calves for the timely herd repairing.However, despite on visible advantages , researches and practitioners don't have one common point of view concerning the using of sexed seed.[5][6][7].It connected with number of researches and their database, which shows that real advantages of this very method reduces the percentage of stockability in cows.Therefore, studying of influence the sexed seed using for reproductive qualities of cows is relevant [3].
The aim of researching was studying the effectiveness of using sexed seed on uterine herd with Holstein cattle.

Materials and methods of investigation
Works concerning the using and studying sexed and traditional seed, were made on a basis of large cattle enterprise, contained about 6 thousand cows of Holstein cattle.
Into the enterprise sexed seed is used more for insemination of clinically healthy heifers, concerning the certain scheme: heifers are usually inseminated by sexed seed and then after 30 days are required an ultrasonic control of the stack capacity of animals and if results won't be satisfied-animal should go through the same procedure again, but now using the sexed sperm only.If the third and next insemination is failed, it goes the traditional seed then.
Also, the clinically healthy cows of the first heifer are inseminated by sexed seed.These animals being inseminated by a separated sexually sperm just once, with a forward control of the pregnancy in 30 days.If pregnancy doesn't confirm, then next insemination will conduct with the traditional seed.
An average milk productivity of enterprise animals is more than 8,000 kg of milk per fodder cow.All animals were into the same conditions of feeding and maintenance concerning their age group and status.
An evaluation of effectiveness using of sexed seed into intensive milk production conditions was carried out during the period of 2019-20.Trough this period 1922 heads was inseminated by sexed seed and 4038 by the traditional.

Results of investigation
An artificial insemination in enterprise is being conducted by cervical method with a rectal fixation of cervix.Companies use schemes of synchronization of Presynch and Ovynch to synchronize sexual cycle of the cows.The traditional seed uses for cows of the second lactation and more, and heifers, which were treated before.Sexed seed uses with clinically healthy heifers and cows of the second lactation.The pregnancy test will be carried out after 30 days of pregnancy using the portable ultrasonic scanner with the rectal censor.
During the period of researching there were 4038 animals inseminated by traditional seed, including 3514 cows and 524 heifers.A total of 3166 heads were calved, 2771(78,9%) from them are cows and 395(75,4%) are heifers.As a result of insemination there weren't calved 872 heads, which was 21,4%.The total cows' litter was 2821 heads, 1607 were male and 1214 female.The total heifers' offspring was 395 heads, 217 from which were female and 178 male.
Base on the data obtained, we can get the best result using of sexed seed was obtained by insemination of heifers -percentage of calved animals was 88,1%, at the same time while when inseminated first-calf heifer was only 47%.It is marked the high percentage of females as from heifers as from cows, which total was 87% and 88,1%.Supplying company of sexed sperm can guarantee a 90% yield of the animals of the desired sex, but the percentage of insemination couldn't be predicted and being guaranteed, because it depends on qualifications of the inseminators, physiological animal conditions in the farm and conditions of their containing.Moreover, the number of specialists note a lower fertility when sexed sperm was used, which is observed in our studies only when it is used concerning the insemination of healthy cows.

E3S Web of
An important indicator of the effectiveness of the herd reproduction program is calf crop per 100 cows, the enterprise total of which during 2019 year was 76% with the use of sexed seed, and 88% with the use of traditional seed, which is 1,16 times higher.
During the study of sexed seed influence on a heifer's fertility the retrospective data from 2018-2019 period were investigated (figure 1).The total results have shown that when we used sexed seed, the percentage of calved animals was from 71 till 77%, which was 10% lower, than with traditional seeds.In the analysis of the data by the number of viable calves produced, it was noted, that while using sexed seed, the yield of the calves was 66-76% and 80-88% of traditional seed using (figure 2) An important indicator for increasing the profitability of the diary livestock industry is the yield of heifers.The data from our investigation give us a confidence, the yield of heifers when we use the sexed seed is stable more than 85%.In the last three years it was noted the decrease of female calves, obtained by using the traditional seed from 56% in 2018 till 39% in 2020.

Conclusion
We can make some conclusions on the example of this operation, that the fertilization ability of seed is 5-8% lower, than using the traditional one, which can be concern with much lower viability of spermatozoids after the sex separation procedure.The yield of calves per 100 cows during the researchable period was higher when traditional seed was used, which notes during the retrospective investigation also.
When we use the sexed seed, the quantity of female calves is more than twice, than when we use the traditional seed, and the calf yield ranges from 80-85 per cent.Based on the research conducted, it can be concluded that in order to increase the efficiency of insemination of sex-separated sperm, it is necessary to use it only for insemination of heifers.The use of sexed sperm to inseminate cows is inefficient and costly, as the number of calved cows is within 47%.

Fig. 3 .
Fig. 3.The heifers are on the total number of calves born.