In South Africa, assisted reproductive technologies (ART) such as oestrus synchronization and AI in cattle have traditionally been applied in commercial production systems but not communal production systems because of several challenges such as infrastructure and cost. The study was designed to assess factors affecting response to oestrus synchronization, conception, and calving rate of organised communal cows following timed AI in Limpopo province, South Africa. A total of 140 cows were selected from organised communal villages and categorized according to body condition score (BCS), parity, age, frame size (small to medium) and breed type (Nguni, Bonsmara, and Brahman). A 9-day CIDR® (Pfizer Laboratories, New York, NY, USA) protocol was used to synchronize the selected cows. Heat mount detectors (Karma®; Four Lakes) were used to assess oestrous synchronisation responce. The AI was done twice at 36 and 48 h post-CIDR® removal using Nguni frozen–thawed semen. Pregnancy diagnosis was performed 90 days following AI using ultrasound scanner and trans-rectal palpation. Data on influence of factors such as BCS, parity, age, district, breed type, and frame size on oestrus response, conception and calving rate were analysed using logistic regression procedure of SAS. Of 140 cows synchronized, 75% (105/140) had tripped patches and underwent AI, 41% (43/105) conceived, and 36% (38/105) calved. Parity, age, breed type, and frame size did not significantly affect oestrous synchronisation response, conception, and calving rate. However, BCS significantly (P = 0.0042) affected calving rate, whereby cows in BCS of >3 had a greater probability of success than those with BCS ≤3. Small-framed Nguni and Bonsmara type cows in their first parity with a BCS ≥3 had greater odds of conceiving following timed AI. Noteworthy, calving rate in the current study was comparable to other studies under communal areas (South African Vet. Assoc. 2004 75, 30-36; Appl. Anim. Husb. Rural Develop. 2013 6, 48-54). Therefore, the current study demonstrated an opportunity to improve the production of organised communal cattle using superior sire germplasm though assisted reproductive technologies. Cows in organised communal areas have greater probability of conceiving and calving when their condition score is >3, regardless of their age, parity, size, or breed type. It is concluded, therefore, that AI technology should be applied in cows of organised communal farmers to facilitate dissemination and propagation of superior germplasm.

Heat stress during IVF is associated with reduced fertility in cattle oocytes. It may, however, enhance thermo-tolerance or cause detrimental effects on a variety of cell types or organisms, depending on the duration and intensity of the thermal challenge. The aim of this study was to evaluate the developmental potential of cumulus-oocyte complexes (COC) matured for 18 or 24 h and incubated at 39°C or 41°C. A total of 1000 immature oocytes were collected at slaughter from indigenous South African cow ovaries. The COC were randomly allocated (100/treatment) into 2 maturation times (18 or 24 h) and cultured in M199 + FSH-LH-estradiol medium under oil at 100% humidity and 5% CO2 at 39°C or 41°C. Post maturation, oocytes were subjected to normal subsequent embryo conditions. The Bracket and Oliphant medium was used for IVF. All matured oocytes were fertilised for 6 h with frozen-thawed Nguni bull semen at a concentration of 265 × 106. The presumptive zygotes from each treatment were cultured into SOF-BSA medium under oil and incubated at 39°C for assessment of cleavage rate 48 h post IVF. After Day 7 of culture, blastocyst were stained (Hoechst 33323) for nuclei cell count. Statistical analyses was performed using Genstat® software of SAS (SAS Institute, Cary, NC, USA; P < 0.05). Oocytes that were matured for 18 h in 41°C resulted in more 8-cell embryos (41%) compared with those incubated at 39°C (21.6%). However, no difference was observed for cleavage rate at both maturation times and incubation temperatures (41 or 39°C). There was more morula formation from oocytes matured for 18 h (19.6%) and 24 h (19.0%) at 41°C compared to 39°C (8.4%) group. The results further showed more blastocyst formation during 18 h at 41°C (15.2%) than at 39°C (7.4%) and during 24 h at 41°C (11.2%), 39°C (11.4%). However there was no difference in the nuclei cell number during 18 h at 41°C (45.2), 24 h (45.8), and 18 h at 39°C (43.4) of maturation. Thus, there was a significant difference in the nuclei cell numbers at 24 h on 39°C (n = 133.2) and 41°C (n = 45.8). In conclusion, oocytes that were matured for 18 and 24 h at 41°C or for 18 h at 39°C developed further to blastocyst stage on in vitro embryo production, however, with low nuclei cell numbers due to accelerated maturation temperature or shortened maturation period.

The bull’s 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 cow’s 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® (1.9 g), which was removed on Day 7. Prostaglandin was then administered (2 mL) 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 bull’s sperm characteristics were examined by CASA before in vitro fertilization. Data were analysed using ANOVA. Treatment means were compared using the Fisher’s 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.

The processes of semen cryopreservation and thawing affect sperm membrane integrity and motility and increases morphological defects as well as DNA damage. The most influential cause of this is oxidative stress. When endogenous antioxidant capacity of seminal plasma is reduced during the freeze-thawing process, plant extracts exhibiting strong antioxidant activity can be used as supplements for compensation. Baobab oil has gained interest because it is rich in powerful antioxidants, which could protect sperm cells from oxidative damage during cryopreservation. Our study aimed to assess the effects of baobab oil on post-thaw sperm quality parameters in an egg-yolk-based extender. Thirty semen ejaculates were collected from 15 Nguni bulls using an electro ejaculator. Semen samples were randomly allocated to control (no baobab oil), 20μL (1%), 50μL (2.5%), and 100μL (5%) baobab oil per millilitre extender. Following dilution, semen samples were loaded into 0.25-mL semen straws, equilibrated for 4h at 5°C, and transferred into a controlled rate programmable freezer. The frozen semen straws were stored in a liquid nitrogen tank (−196°C) until thawing. Semen straws were thawed (37°C/60 minutes) after 1 week of cryopreservation and analysed for (1) sperm motility using a computer-aided sperm analyser, (2) morphological defects and viability using eosin-nigrosin stain, (3) membrane integrity by hypo-osmotic swelling test, and (4) DNA integrity by terminal deoxynucleotidyl transferase dUTP nick end labelling assay. Data was analysed using analysis of variance. Treatment means were compared in relation to the control group by Dunnett's test. We found that supplementing semen extender with baobab oil at 1% significantly (P&lt;0.05) preserved sperm DNA integrity (88.3±3.7) and membrane integrity (74.0±4.2) when compared with the control group (71.7±3.7 and 55.8±4.4, respectively). Baobab oil supplementation either at 1% (5.9±0.5), 2.5% (7.2±0.5), or 5% (6.0±0.5) significantly reduced sperm morphological defects compared with control (9.5±0.5). Total motility (1% (72.7%), 2.5% (72.7%), 5% (71.9%), control (59.3%)) and viability (1% (79.1%), 2.5% (79.8%), 5% (77.8%), control (67.6%)) were also improved by supplementation; however, the difference was not significant. In conclusion, it was demonstrated that supplementing bull semen extender with 1% baobab oil protects sperm from morphological defects, maintains membrane integrity, as well as preserves sperm DNA. All the baobab oil supplementation levels preserved post-thaw bull-sperm quality parameters.