Enhancing follicular growth as a prerequisite for GnRH treatment of true anestrum in buffalo

A total of 140 true anestrous buffalo were divided on the basis of receiving short-term (20 days) nutritional supplementation (N, n = 80) or not (WN, n = 60). The animals in N group were subdivided into NQ (n = 40) where the quantity of the offered diet was increased by 20% and NF (n = 40) where the offered diet was supplemented by 3% of dry protected fat. Buffaloes in either NQ or NF were equally allotted on the following treatment regimens: Insulin/GnRH (NQi or NFi, n = 10 for each); rbST/GnRH (NQr or NFr, n = 10 for each); GnRH alone treated (NQG or NFG, n = 10 for each) and saline-treated control (NQc or NFc, n = 10 for each). Insulin-treated subgroups (NQi or NFi) received s/c injection of insulin at a dose of 0.25 I.U./kg on Days 21, 22 and 23 while rbST–treated subgroups (NQr or NFr) received single IM injection of rbST (500 mg Sometribove) on Day 21. GnRH was injected at a dose of 0.020 mg buserelin (5 ml Receptal®) on Day 24 in all subgroups except NQCand NFC where Day 1 was the first day of the short-term nutritional improvement. Buffalo in the WN (n = 60) were equally allotted on the same treatment regimens applied in the first group insulin/GnRH (WNi, n = 15), rbST/GnRH (WNr, n = 15); GnRH alone treated (WNG, n = 15) and saline-treated control (WNC, n = 15). onic scanning of ovaries was conducted on Day 24 to measure largest follicle diameter (LFD). The results showed increases (P < 0.05) in the LFD following nutritional supplementation with insulin or rbST. The recorded EIRs for GnRH pre-treated with nutritional improvement – metabolic hormones combinations (9/10 and 8/10 for NQi and NFi or 8/10 for NQr) were greater (P < 0.05) than those pre-treated with either metabolic hormone alone (7/15 for WNi and/or WNr) or nutritional improvement alone (6/10 for NQG and/or NFG) and control as well. The greatest CR was recorded in the NQi group. ld be concluded that pre-GnRH nutritional improvement plus administration of insulin or rbST increases LFD in true anestrous buffalo having LFD < 8.5 mm thereby increasing their fertility response to GnRH in terms of EIRs and CRs.