Fertility response using three estrus synchronization regimens in lactating anestrous buffaloes

Abstract

The objective of present study was to elucidate the efficacy of 3 estrus synchronization regimens for optimizing fertility in lactating anestrous buffaloes. Regimen1 (9, GPG), buffaloes were administered (i/m) gonadotropin releasing hormone (GnRH, 0.02 mg) on day 0 and 9, and prostaglandin F_2α (PGF_2α, 500μg cloprostenol sodium) on day 7; regimen 2 (17, GPG+CIDR), in addition to regimen 1, buffaloes were inserted per-vaginally a controlled internal drug release (CIDR, 1.38g progesterone) device for 7 days (day 0–7); regimen 3 (14, GP-hCG), in this regimen, the second- GnRH of the GPG regimen was replaced by human chorionic gonadotropin (hCG, 3000 IU, i/m). Artificial insemination was carried out on days 10 and 11 at 24 h interval. Buffaloes failing to conceive and returning to estrus were again inseminated at their spontaneous estrus. Subsequent to first-GnRH, with or without CIDR device, a good synchrony in the stage of estrous cycle on day 7 was evident as the diameter of largest follicles was not less than 10 mm and was similar between regimens. On day 10, the diameter of largest follicle was more in buffaloes synchronized with CIDR. Buffaloes administered a CIDR device exhibited better estrus behaviour at 48 (day 9) and 72 (day 10) h after CIDR withdrawal compared to controls (GPG). First service conception rate and total % of buffaloes conceived were higher in the buffaloes of GPG+CIDR regimen compared to other regimens. Treatment with CIDR withdrawal had no additional beneficial impact on plasma estradiol at induced-estrus. The body condition score, lactation status, thyroid hormone status and blood biochemical (glucose, total cholesterol, triglycerides, total proteins, creatinine and blood urea nitrogen) profiles were similar between buffaloes of various regimens. In brief, GPG+CIDR based synchronization regimen followed by AI at 72 h and 96 h after CIDR withdrawal is most suitable for optimizing the fertility status of lactating anestrous buffaloes.