STUDY ON EFFECT OF MULTIPLE OVULATION AND GnRH TREATMENT ON EMBRYO RECOVERY AND QUALITY IN PUREBRED AND CROSSBRED SAHIWALCATTLE WITH REFERENCE TO CIRCULATING OVARIAN STEROIDS
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Date
2007
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AAU, Anand
Abstract
Study on effect of multiple ovulation and GnRH treatment on embryo recovery and quality in pure and crossbred Sahiwal cattle with reference to circulating ovarian steroids was conducted, at Sabarmati Ashram Gaushala (SAG), Bidaj in Kheda district of Gujarat state, on 24 animals (Group A: 6 purebred Sahiwal cows; Group B; 6 purebred Sahiwal heifers; Group C and D: 6 HF X Sahiwal crossbred cows each). For induction of multiple ovulations, FSH-P (Folltropin-V Bioniche, Canada), @ 200 mg per donor (8 equal doses of 1.25 ml each) was administered by i.m. route over four days at 12 hr interval, starting day 9 -11 post estrus. A single dose of PG was given 48 hr after the first FSH injection, to bring the donor in heat. The first Al was done 48 hr after PG injection, followed by two more Al at 12 hr intervals. A dose of 2.5 ml Receptal (GnRH) was given to the cows of Group D only at the time of Al. On day 7 of first Al, all the donors were flushed for embryo recovery by standard non-surgical technique. The recovered embryos were classified as viable and degenerated embryos and un-fertilized ova. Viable embryos were further graded as A (Excellent), B (Good) and C (Fair). The blood plasma samples were analysed for estrogen and progesterone concentrations using Radio Immuno Assay (RIA). Among the six purebred Sahiwal donor cows (Group A), only 3 donors (50.00%) responded to treatment with the total number of CL to be 17 (5.67/donor) and a total of 10 (3 VE and 7 degenerated) embryos. The mean recovery of total and viable embryos for responded donors and overall were found to be 3.33 and 1.00 and 1.67 and 0.50 embryos per flush, respectively. All the purebred Sahiwal heifers (Group B) responded to treatment with the total number of CL to be 50 (8.33/donor) and a total of 37 (18 VE; 2 UFO; 1 zona and 16 degenerated) embryos. The mean recovery of total and viable embryos was found to be 6.17 and 3.00 embryos per flush, respectively. Four (66.67%) HF X Sahiwal crossbred cows (Group C) responded to treatment with the total number of CL to be 28 (7.00/donor) and with 17 (3 VE; 11 UFO; no zona and 3 degenerated) embryos. The mean recovery of total and viable embryos for responded donors and overall were found to be 4.25 and 0.75 and 2.83 and 0.50 embryos per flush, respectively. Among the six HF x Sahiwal crossbred cows (Group D), 5 (83.33%) cows responded to treatment with the total number of CL to be 31 (6.20/donor) and a total of 21 (12 VE; 6 UFO; no zona and 3 degenerated) embryos. The mean recovery of total and viable embryos for responded donors and overall were found to be 4.20 and 2.40 and 3.50 and 2.00 embryos per flush, respectively. The Sahiwal heifers (Group B) yielded comparatively higher number of mean ovulations (8.33) and embryos, both total (6.17) as well as viable (3.00), than those of the cows under Group A (3.17, 1.67 and 0.50, respectively). Comparatively better response was observed in crossbred cows (Group C: 4.88 mean ovulations and 2.83 total embryos) than in purebred Sahiwal cows (Group A: 3.17 mean ovulations and 1.67 total embryos). Comparatively higher response to multiple ovulation treatment and higher recovery of total and viable embryos (5.33, 3.50, 2.00, respectively) were observed in crossbred cows of Group D than in crossbred cows of Group C (4.83, 2.83, 0.50, respectively). The mean number of ovulations for superovulatory responsive (SR) and non-SR cows were found to be 6.33+1.83 and 0.67+0.27, respectively. Mean age in months and parity of SR and non-SR donor cows were 70.75 ± 20.42, 3.17 ± 0.91 and 96.67 + 39.46, 3.83 ± 1.56, respectively. No significant variation was found in blood plasma concentrations of progesterone among four groups of donors for all the stages of MOET. The mean blood plasma concentrations of estrogen varied significantly between groups. The mean blood plasma estrogen concentrations were found to be significantly (t=3.293, p<0.05) higher at all the stages of MOET for Sahiwal heifers than cows (t=3.293); for Sahiwal crossbred cows than purebred Sahiwal cows (t=3.955) as well as for crossbred cows (without GnRH) than crossbred cows (with GnRH) with the difference being non significant. The mean blood plasma concentrations of progesterone and estrogen at Stage IV (synchronized estrus; 0.42+0.17 ng/ml and 18.50+7.55 pg/ml, respectively) and at Stage VII (at PG injection during FSH treatment; 1.85+0.76 ng/ml and 12.67+5.17 pg/ml, respectively) in purebred Sahiwal heifers (Group B) were found to be correlated significantly with the rate of ovulation, i.e., 8.33 ovulations/donor (R2=0.902, p<0.031; R^=0.831, p<0.069, respectively).The mean blood plasma concentrations of progesterone and estrogen at Stage VI (initiation of FSH treatment; 1.90+0.77 ng/ml and 37.50+15.31 pg/ml, respectively) and at Stage VII (at PG injection during FSH treatment; 2.05+0.84 ng/ml and 37.00+15.11 pg/ml, respectively) in HP x Sahiwal crossbred cows (Group C) were found to be correlated significantly with the rate of ovulation, i.e., 4.83 ovulations/donor (R2=0.898, p<0.033; R2=0.841, p<0.064, respectively). The plasma concentrations of estrogen remained to be the highest at superovulatory estrus in all four groups (A, B, C and D) of donors (39.33+16.06; 18.33+7.48; 60.33+24.63 and 49.17+20.07 pg/ml, respectively). The mean blood plasma progesterone concentration declined significantly after PG injection during FSH treatment (Stage VII) and on the day of superovulatory estrus (Stage VIII) in all groups (A, B, C and D) of donors (2.11+0.86 to 0.25+0.10; 1.85+ 0.76 to 0.73+0.30; 2.05+0.84 to 0.27+0.11 and 1.84+0.75 to 0.41+0.17 ng/ml, respectively). For SR and non-SR donors, the mean number of ovulations and recovery of total and viable embryos were found to be 6.33+1.83, 4.00+1.15 and 1.50+0.43; and 0.67+0.27, nil and nil, respectively. The SR cows (n=12) yielded a total of 48 embryos comprising 18 (37.50%) viable embryos (@ 1.50/flush) and remaining 30 (62.50%) to be either un-fertilized ova (17) or degenerated embryos (13). The mean plasma progesterone and estrogen levels have been found to be substantially higher in SR donor cows than non- SR donor cows at all the stages of MOET. The total number of ovulations did not vary significantly between donors of Group C and D (29 Vs 32). However, there was a significantly higher recovery of viable embryos in Group D (12 VE; @ 2.0/flush) than that of Group C (3 VE; @ 0.5/flush). Based on the results obtained, it was concluded that since purebred Sahiwal heifers had superior SOV response to gonadotrophin treatment and higher recovery of total and viable embryos as compared to Sahiwal cows, heifers can be used as potential embryos donors. The significantly higher levels of mean blood plasma progesterone and estrogen in SR cows than in non-SR cows are indicative of possible underlying role of sound profile of ovarian circulating steroids in contributing towards better results of MOET. Administration of GnRH at the time of Al in superovulated donors may help in increasing the fertilization rate and recovery of more viable embryos of superior quality. Decreasing superovulatory response in donor cows with an increase in cows' age, parity and lactational stress, is suggestive of the use of young and stress free animals for MOET work.
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Veterinary Obstetrics and Gynaecology, A Study