Biomedical subjects
JP Greyling
Publications and source records attributed to JP Greyling.
Reproduction traits in the Boer goat doe.
The aim of this review is to give insight into the reproduction potential of the Boer goat doe. Assessment of the reproduction traits in the Boer goat doe demonstrates a mean body weight at puberty of between 30.6 and 27.5kg, depending on the dietary energy level. Kids weaned during the natural breeding season (April/May) exhibit oestrus or puberty earlier than those weaned outside the natural breeding season. The mean age at the onset of puberty in the Boer goat doe is 191.1 and 157.2 days for kids born in August (late winter) and January (mid-summer). Although periods of complete anoestrus was not observed, the peak of sexual activity occurred during autumn and the period of lowest sexual activity from late spring to mid-summer. The duration of the oestrous cycle was recorded as being 20.7+/-0.7 days, with the mean duration of the oestrous period being 37.4+/-8.6h and the position of the LH peak (indicative of ovulation) being 8.0+/-1.5h following the onset of oestrus. The time of ovulation was recorded as occurring 36.8h after the onset of oestrus, with a mean ovulation rate of 1.72+/-0.9 ovulations per doe. The mean gestation period is quoted as being 148.2+/-3.7 days, with multiple births having no significant effect on gestation length. Involution of the Boer goat uterus is macroscopically complete by day 28 post-partum with the duration of the post-partum anoestrous period in the Boer goat being 55.5+/-24.9 days. The mean interval from partus to conception recorded, was 62.0+/-20.2 days. To optimise the reproductive efficiency in the Boer goat doe, it is essential that its reproductive potential be known and exploited.
Synchronization of oestrus in goats: dose effect of progestagen.
A trial was conducted to test the efficiency of different doses of intravaginal progestagen in the synchronization of different goat breeds, in the breeding season. Sixty Multiparous Boer and 60 Indigenous feral does were allocated to three treatment groups. The groups consisted of a control group (natural oestrus) (n=20/breed); 60mg MAP sponge groups inserted for 14 days plus 300IU PMSG at sponge withdrawal (n=20/breed) and halved 60mg MAP (+/-30mg) sponges inserted for 14 days plus 300IU PMSG at withdrawal (n=20/breed). The time from sponge withdrawal to oestrus was not significantly different in the treatment groups (whole and halved sponges), irrespective of breed. The duration of the oestrous period was significantly (p<0.01) shorter in the control group (29.3+/-14.9h versus 28.0+/-15.7h for the Indigenous and Boer goats, respectively), compared to the induced period for the 60mg (31.1+/-14.7 and 31.5+/-15.9h) or 30mg (40.0+/-22.0h versus 34.3+/-21.7h) for the Boer and Indigenous goats, respectively. No significant difference in pregnancy rate following AI was recorded (mean 74.2%). The mean serum progesterone concentration for the observation period varied between 0.01 and 6.19ng/ml for Indigenous and 0.01 and 9.05ng/ml for Boer goat does. No significant correlation was recorded between the does pregnant and serum progesterone levels. Mean serum LH concentration of the 60mg MAP groups (0.59+/-0.22ng/ml) was significantly (p<0.05) lower than the control (0.84+/-0.66ng/ml) and the halved sponge (1.9+/-0.49ng/ml) groups. Dose of progestagen played no role in the efficiency of synchronization, regardless of the breed. The mean pregnancy rate achieved, is acceptable following fixed-time AI in both breeds and at both doses progestagen.