The Use of Physiological Indices in Attempt to Predict the Optimal Time for Artificial Insemination in Dairy Cattle

Cryobiology of Gametes Department, Institute of Biology and Immunology of Reproduction "Acad. K. Bratanov", Bulgarian Academy of Sciences, BG-1113 Sofia, Bulgaria


HRISTOV, P. and St. ZLATAREV, 2004. The use of physiological indices in attempt to predict the optimal time for artificial insemination in dairy cattle. Bulg. J. Agric. Sci., 10: 649-655

The purpose of the current study was to explore the possibility of determining the optimal time for artificial insemination (AI) in dairy cows by relating the values of certain physiological parameters (rectal body temperature, blood pressure, and heart rate) and the manifestation of spontaneous milk ejection (SME). 24 clinically healthy pure breed Simmental dairy cows were divided into two groups. According to the experiment design half of the animals were allocated to the test group (Group A, n=12), and the rest - to the control group (Group B, n=12). The values of rectal body temperature, heart rate and blood pressure were measured in animals from group A during four test periods: proestrus, estrus, SME and early metestrus. In animals from Group B we performed none of the above measurements. The cows from group A were artificially inseminated (AI) with frozen-thawed semen immediately after manifestation of the SME. The animals in a group B were artificially inseminated with frozen-thawed semen according to the conventional a.m.-p.m. rule. All cows were palpated per rectum after 30 days from AI to determine pregnancies. We obtain a very high conception rate (83.3%) with artificial insemination of cows from Group A conducted during the third tests period, while the conception rate of cows from Group B was 36.8%. The results obtained, in terms of conception rates of animals from group A, make us not entirely unjustified in claiming that the values of the physiological parameters under examination could be used as highly informative indices with respect to the determination of the optimal time for artificial insemination of cows.

Key words: estrus, spontaneous milk ejection reflex, AI, dairy cow