Effect of intrauterine recombinant bovine interleukin-8 (rbIL-8) administration to dairy cows on conception rate in the postpartum period

The objective of this thesis is to ascertain the impact of the intrauterine administration of recombinant bovine interleukin-8 in primiparous Holstein cows in the postpartum period on the conception rate at first insemination, weekly milk yields over 90 days postpartum, and blood serum levels of beta-hydroxybutyric acid (BHBA), calcium (Ca) and non-esterified free fatty acids (NEFA). For this purpose, 40 primiparous cows aged between 24 and 35 months, whose births were not assisted and whose placentas were expelled without assistance within 24 hours after calving, and whose clinical examination findings were healthy, were selected. The selected cows were divided into two groups: the intrauterine recombinant bovine interleukin-8 group (IL-8 /n=20) and the control group (Con/ n=20). The IL-8 group received an intrauterine administration of 1,250 µg rbIL-8 + 500 mL 0.9% NaCl, while the Con group received only an intrauterine administration of 500 mL 0.9% NaCl. In cows in the IL-8 and Con groups, the day of intrauterine administration was designated as "day 0", and metabolic profile analyses were performed on blood samples collected on days 0, 7, and 21. The weekly milk yields of cows in the IL-8 and Con groups were recorded up to postpartum day 98. On the 50th day following the birth, the cows in both groups were subjected to the presynch+ovsynch protocol and underwent fixed-time insemination. A pregnancy examination was performed on cows that underwent artificial insemination on the 35th day. As a result of the pregnancy examinations conducted, no statistical difference was determined between the IL-8 and Con groups in terms of pregnancy rates at first insemination. According to the biochemical analysis results, the IL-8 group was found to have lower serum NEFA and BHBA values on day 7 compared to the Con group. In conclusion, postpartum intrauterine rbIL-8 administration was found to have no significant effect on conception rate, weekly milk yield, and milk fat/protein/electrical conductivity data; however, it may have an effect on NEFA and BHBA levels in the early postpartum period.