The Effects of Improved Feeding and Hormonal Treatments on Reproductive Performance of Desert Goats in the Sudan

Abstract

The study was conducted to investigate the effects of feed supplementation and hormonal treatment, using Controlled Internal Drug Release Device (CIDR) and different doses of eCG, onthe reproductive performance of Desert goats and to study the effects of feed supplementation and postpartum administration of GnRH or PGF2αon postpartum length and kidding interval. To realize these objectives three experiments were conducted. The first experiment involved 60 matured females divided into three groups (20 in each). These groups in addition to grazing were supplemented with concentrate ration at the rate of 0.0, 0.25, and 0.5 kg/head/day thus forming three groups: A, B and C, respectively. Again, according to the eCG doses given, each group was divided into two equal sub-groups (10 in each). Oestrous cycle in all the groups were synchronized with CIDR for 13 days followed by administration of 500 i.u or 700 i.u eCG immediately followingremoval of CIDR. Regardless of appearance of signs of oestrous, does were artificially inseminated 48-52 hours after CIDR removal, using fresh diluted semen. Goats, which returned to oestrus, were artificially re-inseminated. The treatments were randomly assigned in a factorial experiment using completely randomized design. The reproductive traits measured in this experiment included oestrous response, interval from removal of CIDR to occurrence of oestrous, durationof oestrous, non-return rate, pregnancy rate, kidding rate, twinning rate, litter size, gestation period and progesterone profile during gestation. The results indicated that all hormonal protocols were capable of inducing and synchronizing oestrus in the Sudanese Desert goats. However, the response of does to oesrtus was observed in 85%, 75% and 75% for treatment groups A, B and C, respectively, with the highest value scored by group A (P<0.05). The mean interval from removal of CIDR to occurrence of XIV oestrus was 37.68, 28.62 and 33.35 hours for treatment groups A, B and C, respectively. The eCG doses had significant effect on the interval of oestrous occurrence. The oestrous duration was 27.29, 27.56 and 31.60 hours for treatment A, B and C, respectively. The overall non- return rate was 85% for group A, 80% for B and 80% for C, with significant difference between treatment groups. The overall kidding rate was 70.84%, 74.61%and 65.14% for treatment groups A, B and C, respectively, with significant difference. Where 500 iu eCG had significant higher kidding rate than 700 iu eCG (P< 0.5). The twining rate was significantly higher (P< 0.5) for the doesin treatment group B, intermediate in group C, and lower in treatment group A. The litter size was significantly higher for does in treatment groups B and C compared to group A. The mean birth weight of the kids were 2.04, 2.08 and 2.25 kg for treatment groups A, B and C, respectively. The male kids had heavier birth weight than female kids. However, the singleton kids had greater birth weight than twin kids. The mean gestation period was 151.22 for A, 149.69 for Band 151.25days for C. Does with triplets had a significantly (P < 0.05) shorter gestation length than those with twins and singleton. The gestation length of the does which were bearing male kids was longer than those bearing female kids. The mean serum progesterone concentration during pregnancy was 5.93, 5.51and 5.47ng/ml for treatment groups A, B and C, respectively. The progesterone level began at 1.34 ng/ml and then rose to reach 13.82 ng/ml as a maximum level, then declined and remained above 1 ng/ml until the end of the gestation period at parturition. The second experiment involved dividingdoes shortly after kidding into three sub-group comprising untreated group A and GnRH or PGF2αtreated groups B and C, respectively. The first postpartumoestrous to determine the postpartum period was monitored using a vasectomizedbuck and hormonal assay to detect XV the first rise of progesterone in the blood. The results showed that the mean postpartum period was 52.87 for A. 48.53 for B, and 49.47days for C. GnRH treatment showed significantly shorter postpartum period than the control and PGF2α(P<0.05). The third experiment involved monitoring the does for two successive oestrous cycles, then all the groups were subjected to oestrous synchronization using CIDR and administration of 500 i.u eCG followed by artificial insemination as in the first experiment. The mean kidding interval for the treatment groups A, B and C were 248.03, 238.73 and 242.80 days, respectively, with group B showing significantly shorter interval (P<0.05). It could be concluded that feed supplementation with hormones improves the conception rate, kidding rate and litter size and shortens kidding interval. Therefore, with improved management ofDesert goats, the owners can harvest four kid crops at 27 months interval. The study recommended further research on the effect of season on the success rate of different hormonal protocols used for oestrous synchronization.