J.P.C. 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.

Different synchronization techniques in Boer goat does outside the normal breeding season

Synchronization techniques outside the normal breeding season were evaluated on 85 Boer goats with intravaginal progestagen sponges, sponges plus prostaglandin, and two injections of prostaglandin, with or without 500 IU PMSG. Oestrous response following the double prostaglandin injection regime was significantly (P < 0.01) lower than in the intravaginal sponge and sponge plus protaglandin groups (with and without exogenous PMSG). The PMSG led to a higher (P < 0.01) oestrous response in goats treated with intravaginal sponges only (100.0% vs. 53.3%). Administration of 500 IU PMSG led to a shorter time interval (P<0.01) from cessation of treatment to the onset of oestrus in the intravaginal sponge and sponge plus prostaglandin groups (40.0 vs. 72.1 hr and 39.3 vs. 71.3hr, respectively). Time interval from treatment to the LH peak was shorter (P<0.01) in the groups (excluding the double injection prostaglandin groups) receiving 500 IU PMSG, with no significant difference between the two intravaginal sponge treated groups. No significant differences in the time interval between LH peak and onset of the oestrous period was recorded between treatment groups. There was no significant difference in fertility between the intravaginal sponge and sponge plus prostaglandin groups (73.3 vs. 66.7% with PMSG and 53.3 vs. 60.0% without PMSG). Intravaginal sponge and sponge plus prostaglandin techniques (with PMSG) are effective as synchronizing agents outside the breeding season in Boer goat does. The double prostaglandin injection regime on the other hand proved ineffective outside the breeding season.

Ovulation in the boer goat doe

Abstract A total of 40 Boer goat does were slaughtered 26 ( n = 15), 32 ( n = 10) or 38 ( n = 15) h after onset of oestrus. Blood was sampled from eight does in each group for serum progesterone and LH concentration determinations from the time of onset of oestrus to slaughter. Follicular activity (follicles greater than 0.2 cm) in the ovary increased significantly ( P Mean interval from onset of oestrus to the pre-ovulatory LH peak was 11.3 ± 4.3; 13.1 ± 3.0 and 10.5 ± 4.1 h for the groups slaughtered at 26, 32 and 38 h, respectively. The interval between the LH peak and ovulation was relatively constant at 24.7 h for all does. Knowledge of the time of onset of the LH peak permits approximate predictions regarding the time of ovulation.

Macroscopic uterine involution in the post-partum Boer goat

Abstract Sixteen Boer goat does were slaughtered at different intervals between parturition and 34 days post-partum and all the relevant macroscopic uterine measurements recorded. Involution of the post-partum uterus and macroscopic changes of different parameters are described and predicted in the Boer goat by Y = A e Bt + Ct 2 . Considerable anatomical variation existed between individuals, but the objective was to monitor when the uterus had macroscopically involuted. Mass and volume of the uterus declined drastically after parturition. According to the model, the involution process was complete by 27.0 and 27.4 days for the uterus mass and volume, with rate of decrease 17.2 ± 2.7% and 20.8 ± 3.0%/day for the first 34 days post-partum, respectively. The external diameter of the cervix decreased in size from 7.5 cm following parturition to approximately 2.0 cm by day 4 post-partum. This decrease was theoretically complete 20.7 days post-partum. Similarly the external diameter of the body of the uterus was static 21.3 days post-partum with a rate of decrease of 12.4 ± 2.5%/day. Mean length and diameter of the uterine horns reached normal, non-pregnant size by 24 and 27.9 days post-partum, respectively. Diameter of the largest caruncles exhibited an initial fast decline (11.2 ± 1.7%/day for the entire observation period), tapering off towards the end of the period. Caruncles were “back to normal” by 26.3 days post-partum. The involution process of the uterus was macroscopically complete by approximately 28 days post-partum in the Boer goat.

Oestrous synchronisation and pregnancy rate following artificial insemination (AI) in South African indigenous goats

The study evaluated the effect of duration of progestagen treatment and breed on response to oestrous synchronisation and pregnancy rate following AI in 47 Boer and 27 unimproved indigenous goats. Each breed was subdivided into two groups, based on the duration of progestagen treatment. In the long-term progestagen treatment, controlled internal drug release dispensers (CIDRs) were inserted for 16 days, while in the short-term progestagen treatment, CIDRs were inserted for 9 days. Oestrous detection was performed for a period of 72 h, starting at CIDRs withdrawal. AI was performed 48 h following CIDRs removal with raw or frozen/thawed semen. Pregnancy diagnosis was performed at day 35 following AI. Boer goat exhibited a significantly (p <0.05) higher oestrous response (100%) than unimproved indigenous goats (88.9%). Breed had no effect on the onset of oestrus. Boer goat does recorded a longer duration of the induced oestrous period, compared to the unimproved indigenous goats. No significant difference was observed between short or long-term progestagen, with respect to the oestrous response, onset and duration of the induced oestrous period. The pregnancy rate was not affected by breed and semen cryopreservation. However, long-term progestagen treatment drastically reduced pregnancy rate. In conclusion, breed had an effect on oestrous response and the duration of induced oestrous period. The interaction of breed and duration of progestagen treatment had no effect on response to oestrus and onset of oestrus. The pregnancy rates of the current study were generally low and were affected by the duration of progestagen treatment.

Effect of an anabolic steroid on body measurements in ram lambs

Abstract Twenty Ile de France ram lambs were allocated to two groups following weaning. One group (n= 10) was treated weekly with an intramuscular injection of an anabolic steroid (50 mg nandrolone laurate ) for a 12-wk period. The other group (n= 10) served as a control. Treatment with an anabolic steroid did not significantly increase mean shoulder width (22.8 vs. 22.0 cm), shoulder height (61.7 vs. 60.8 cm), body length (72.8 vs. 70.2 cm) and body weight (42.5 vs. 39.8 kg). Scrotal circumference and testes volume were significantly (P Although use of the anabolic steroid in young ram lambs did not result in a significant increase in muscle deposition, the androgenic effect retarded testicular development and could possibly affect the future reproductive performance of the ram.

15 QUANTIFICATION OF BULL SPERM TRAITS AS ASSESSED BY COMPUTER-ASSISTED SEMEN ANALYSIS AND THE RELATIONSHIP TO PREGNANCY RATE FOLLOWING CONTROLLED BREEDING

The bulls contribution through artificial insemination to reproductive efficiency is of great biological importance. The objectives were (1) to compare the oestrous synchronization response of Bonsmara and Nguni cows; and (2) to find the relationship between cows conception rate (in vivo and in vitro fertilization) and bull sperm motility rate assessed by computer-assisted semen analysis (CASA) following AI. For the in vivo sperm fertility test, 100 Bonsmara and 482 Nguni cows were randomly selected and subjected to oestrous synchronization protocol and AI with frozen-thawed assessed semen by CASA before AI. Briefly at Day 0, cows were inserted with an intravaginal CIDR® (1.9g), which was removed on Day 7. Prostaglandin was then administered (2mL) on Day 8 and a heatmount detector was placed on the hindquarter of each cow. For the in vitro sperm fertility test, collected oocytes from slaughterhouse were in vitro matured (n=360) and in vitro fertilized (sperm/mL) in 100-µL droplets (final volume) of BO-IVF medium per treatment bulls (Bonsmara or Nguni bull). The frozen/thawed semen straws of Bonsmara and Nguni bulls were randomly selected and used under the same IVF conditions. The thawed bulls sperm characteristics were examined by CASA before in vitro fertilization. Data were analysed using ANOVA. Treatment means were compared using the Fishers protected least significant difference t-test. There was no significant difference in oestrous response for the Bonsmara (83.0%) and Nguni (90.8%) cows, respectively. The Bonsmara cows recorded a significantly higher pregnancy rate (59.0%) compared with the Nguni (37.1%) cows (P<0.05). Sperm traits such as total motility (TM), progressive motility and rapid were found to be positively correlated with conception rate (r=0.06, 0.03, and 0.08, respectively; P<0.01), although correlations were low. There was no difference in the average frozen-thawed sperm TM rate of Nguni (92.2%) and Bonsmara (81.0%). There was a lower fertilization rate following IVF with Bonsmara and Nguni bull sperm. In conclusion, Nguni cows had similar oestrous response as Bonsmara cows. The sperm traits from Bonsmara and Nguni bulls were found to be related to in vivo conception and in vitro fertilization rate when sperm cells were assessed by CASA technology. However, the pregnancy rate was lower in Nguni cows.