Estradiol Priming Potentiates the Kisspeptin-Induced Release of LH in Ovariectomized Cows

Uterine Tube Resection by Vaginotomy as an Alternative to Ovariectomy in Mature Cattle

The prevention of pregnancy is desirable for female cattle destined for sale in the northern Australian rangelands for both economic and welfare reasons. Controlled access to bulls is often not feasible, nor are any non-surgical methods currently available. Many females are therefore surgically spayed. This study describes a technique for uterine tube resection (UTR), which leaves the ovaries intact and is performed using a vaginal approach, and compares the outcomes from 70 Brahman cows subjected to the procedure with 60 heifers spayed using the dropped ovary technique. The animals were monitored for 10 days following the surgery. There were no mortalities, and two animals were treated for illnesses after the UTRs and recovered. The animals subjected to both surgical procedures showed signs of pelvic discomfort and mild inflammation during recovery. The cows gained an average of 9.3 kg (SD 14.5 kg) of weight over the 10 days of the study compared to the spayed heifers, which lost 3.5 kg (SD 13.3 kg), with 19 and 63% of the animals in each of the groups losing weight, respectively. Uterine tube resection can be considered as a viable alternative to surgical spaying.

Effects of kisspeptin-10 on the reproductive performance of sows in a fixed-time artificial insemination programme

Kisspeptin (KP) is a major positive regulator of the hypothalamo-pituitary-gonadal axis and affects female reproductive cyclicity in mammals. It offers an attractive alternative strategy to control reproduction in fixed-time artificial insemination (FTAI) protocols. We aimed to evaluate the effects of different doses of kisspeptin-10 (KP-10) on sow reproductive performance in FTAI protocols. One hundred ninety-eight weaned sows were divided into three groups at random. A FTAI-GnRH group of sows (n = 98) received 100 µg (2 mL) gonadotropin-releasing hormone (GnRH; gonadorelin) by intramuscular injection at 96 h after weaning (t = 0 h); FTAI-KPL (KPL: low-dose KP-10, n = 50), and FTAI-KPH groups of sows (KPH: high-dose KP-10, n = 50) received 0.5 or 1 mg KP-10 (2 mL) respectively at 96 h after weaning. Sows were checked twice daily for oestrus. Ultrasonographic evaluations were performed to determine the follicular diameter and time of ovulation; blood samples were collected immediately before injection (t₀ = 0 min) and at 15, 30, 45, 60, 75, 90 min, 24 and 48 h postinjection. Sows were inseminated at 112 and 132 h after weaning. The oestrus rates (96 vs 92%; 96 vs 88%) and weaning-to-oestrus intervals (98.9 vs 98.6 h; 98.9 vs 97.1 h) were not affected by treatment, but oestrus in the FTAI-KPL group was significantly longer than in the FTAI-GnRH group (38.7 vs 30.0 h; P < 0.05). The peak LH concentrations were 1.29 times greater than at t₀ = 0 in the FTAI-GnRH group, and 1.45 and 1.44 times greater than at t₀ = 0 in the FTAI-KPL and FTAI-KPH groups, respectively. Follicular diameters and pregnancy rates (86 vs 88%, 86 vs 80%, respectively) did not differ between the treatments. Moreover, the total numbers of piglets born and those born alive did not differ among the three groups. These findings suggested that 0.5 mg KP-10 given at 96 h after weaning could be used in FTAI programmes to manage batch farrowing in sows.