Optimal timing of artificial insemination in gilts

Abstract

In the article it is highlighted the results of research on the features of cervix permeability and optimal periods of fertilization in pubertal gilts. Five high-productive boars of the Large White breed, aged 18-36 months, were used in experiments and evaluated for the quality of sperm. The start of the estrus was carried out using a test boar. In the first experiment to determine the permeability of the cervical canal, 3 groups of the Large White breed were formed for 15 heads in each, which were inseminated at the onset: of the first (1st group), the second (2nd group) and the third period of the estrus at the age of 6 - 8 months. Gilt were fertilized with a sperm dosage of 70 ml of a diluent containing 2 billion of spermatozoa. In the second experiment to determine the optimal timing of insemination, 66 gilt of the Large White breed aged 8 to 9 months, live weight 110-130 kg, with clear signs of the start of proestrus, estrus and diestrus were used. The beginning of the estrus was set twice a day at 7 o'clock and 19 o'clock. The doses of sperm (2 billion of spermatozoa in 70 ml of diluent) were injected into the gilts according to the following scheme: Group I - after the prescribed period of the estrus - 0 hours; Group II - after 6 hours; III - group - 12 hours; Group IV - 18 hours; V - 24 hours; VI - 36 hours. It has been determined that cervical permeability increases with age of gilts and the number of reproductive cycles. In gilts, in the first reproductive cycle, the permeability of the cervical canal is 4.61 cm and intensively increases twice: 1.9 (p <0.001) (2nd estrus) and 2.5 times (p <0.001) (3rd estrus). The introduction of sperm by the intracerviсal method on the third period of the estrus allows them to be fertilized at a level of 86 % and receive 10.2 newborn piglets.Cervix permeability in gilts increases from the beginning of the estrus for the next 24 hours. The high indexes of their reproductive capacity are determined at the introduction of sperm dosage in 24-36 hours after the onset of the estrus. The number of live newborns piglets was maximal when sperm is introduced into cervix of gilts in 12; 24 and 30 hours after the start of the estrus. The live weight of newborn piglets depends on the period of the introduction of sperm into the pigs, being maximal at the start of the estrus, and in 24 and 30 hours after the introduction of sperm. The postponement of the procedure up to 36 hours leads to a decrease of this index (p <0.001). Key words: reproductive cycle, estrus, cervix, fertilization, sperm, gilt.