Effect of GnRH on Embryo Recovery and Quality in Crossbred Sahiwal Cows

Abstract

Effect of GnRH on embryo recovery and quality in crossbred Sahiwal cows was studied in 12
crossbred (HF x Sahiwal) cows divided in two groups (Group A: 6 cows without GnRH and Group B: 6
cows with GnRH). For induction of superovulation, FSH-P (Folltropin-V, Bioniche Animal Health,
Canada, @ 200 mg per donor in 8 equally divided doses of 1.25 ml each) was administered by i.m. route
over 4 days at 12 hr interval, starting day 9 -11 post estrus. A single dose of PGF2a (Iliren, lntervet, @ 5
ml) was given i.m. 48 hr after the first FSH injection, to bring the donor in heat. First Al was done 48 hr
after PG injection, followed by two more inseminations at 12 hr intervals. A dose of2.5 ml Receptal (10.5
μg Buserelin Acetate, GnRH Analogue, lntervet International, GmbH, Germany) was given i.m. to cows of
Group B only at the time of first Al. On day 7 of first AI, cows were flushed for embryo recovery. Among
6 cows (Group A), only 4 (66.67%) responded to FSH treatment with the total number of CL to be 28
(7 .00/donor) and a total of 17 (3 viable, 3 degenerated and 11 UFO) embryos. The mean recovery of total
and viable embryos (VE) for responded cows and overall were found to be.4.25 and 0.75 and 2.83 and 0.50
embryos per flush, respectively. Among 6 cows (Group B), 5 (83.33%) responded to FSH treatment with
the total number of CL to be 31 (6.20/donor) and a total of 21 (12 viable, 3 degenerated and 6 UFO)
embryos. The mean recovery of total and viable embryos for responded cows and overall were found to be
4.20 and 2.40 and 3.50 and 2.00 embryos per flush, respectively. There was a significantly higher recovery
of viable embryos in Group B (12 VE; @ 2.0/flush) than of Group A (3 VE; @ 0.5 /flush). The quality of
viable en,bryos recovered from Group B (with GnRH) was higher (83.33% grade A and 16.67% grade B)
than Group A (66.67% grade A and 33.33% grade B). It was concluded that injecting GnRH at the time of
Al in superovulated cows is helpful in increasing the fertilization rate and recovery of more viable embryos
of superior quality.