The purpose of this study was to evaluate how ascorbic acid with dietary flaxseed oil affects the quality and fertility of cryopreserved ram sperm in South African indigenous rams. Treatment diets were supplemented 60 days before semen collection to afford proper spermatogenesis, adaptation to the feed formulated and fed throughout the study. Semen was collected with the use of artificial vagina following dietary supplementation with five treatment diets (neg. cont. - negative control, pos. cont. - positive control, FLO - 5% Flaxseed oil, ASA - 4% Ascorbic acid, and FLO + ASA). Semen was then extended using tris-based extender and cryopreserved using the programmable freezer (CBS Freezer 2100 series, Laboratory consumables & chemical suppliers, America). Ovaries were collected from a neighbouring slaughter house and conveyed to the lab in 0.9% saline at 37 °C. Data (sperm parameters and in vitro fertility) was then exposed to the GLM (General Linear Model) in Minitab 17. Pearson\'s correlation coefficient was utilized to investigate the relationship between cryopreserved sperm quality and in vitro fertility. The student Least Significant Difference Test was used to separate the treatment means, and differences were accepted when the p-value was less than 0.05. The FLO + ASA group had higher (p < 0.05) progressive (36.33 ± 1.87), total (88.24 ± 2.24), rapid motility (27.52 ± 1.74), intact plasma membrane (75.67 ± 2.08), total fertilization (65.98 ± 7.39), and total cleavage (66.19 ± 6.50) when compared to other treatment groups. Total fertilization rate had a medium significant (p < 0.001) medium correlation with the progressive motility (r2 = 0.435), total motility (r2 = 0.447) and rapid motility (r2 = 0.409). In conclusion, dietary flaxseed and ascorbic acid (FLO + ASA) improves cryopreserved semen quality, in vitro fertilization rate, and the total cleavage rate. Noteworthy, the progressive, total and rapid motility play a crucial in the in vitro fertilization rate.

Ticks can compromise productivity and welfare in free-ranging sheep. Chemical tick control may not be sustainable in the long term. Alternative control measures must be sought for an integrated control programme. Birth and weaning weights as well as log transformed overall tick count of indigenous fat-tailed Namaqua Afrikaner (NA), commercial Dorper and NA x Dorper cross lambs were studied under extensive conditions. Relative to NA lambs, Dorper lambs were 22.2% heavier at weaning (P < 0.05). Geometric means for total tick count on Dorper lambs exceeded those of their Namaqua Afrikaner contemporaries by more than twofold (P < 0.05). Relative to the pure-breed midparent value, the mean performance of NA x Dorper lambs was 7.9% more for birth weight, 11.2% more for weaning weight and 26.2% less for the back transformed means for total tick count (P < 0.05). Heterosis for total tick count was slightly greater at -29.3% when data were adjusted for the larger size of NA x Dorper lambs. Crossing commercial Dorper sheep with a hardy, indigenous breed therefore resulted in lower levels of tick infestation without compromising live weight in progeny so derived. Hardy, indigenous genetic resources like the NA should be conserved and used in further studies of ovine genetics of resistance to ticks in South Africa.

A population structure study was performed in South African ovine populations using the OvineSNP50 beadchip. Blood samples were obtained from 295 sheep of which 172 had been identified as smallholder Dorpers, 4 smallholder White Dorpers, 46 purebred Dorpers, 26 purebred South African Mutton Merinos and 47 purebred Namaqua Afrikaners. Blood from the latter three breeds were obtained from a resource flock maintained on the Nortier research farm. Genetic diversity was estimated using allelic richness (A r), observed heterozygosity (H o), expected heterozygosity (H e) and inbreeding coefficient (F). Population structure analysis was performed using fastSTRUCTURE to determine the breed composition of each genotyped individual. The Namaqua Afrikaner had the lowest H e of 0.280 ± 0.18 while the H e of smallholder Dorper, Dorper and South African Mutton Merino did not differ and were 0.364 ± 0.13, 0.332 ± 0.16 and 0.329 ± 0.17, respectively. The average inbreeding coefficient was highest for the pure breeds, Namaqua Afrikaner, Dorper and South African Mutton Merino compared to the average inbreeding coefficient for the smallholder Dorper population. The smallholder Dorper were introgressed with Namaqua Afrikaner, South African Mutton Merino and White Dorpers. Similarly, the smallholder Dorper population was more genetically diverse than the purebred Dorper, South African Mutton Merino and Namaqua Afrikaner from the research farm. The higher genetic diversity among the smallholder sheep may be advantageous for their fitness and can be used to facilitate selective breeding.

The genetics of tick infestation in sheep need study, as host resistance often forms part of integrated pest control programs. Repeated udder health scores, site-specific tick count, mating weight and reproduction records (N=879-1204) were recorded annually from 2010 to 2015 on ewes of the indigenous Namaqua Afrikaner (NA) fat-tailed breed, as well as the commercial Dorper and SA Mutton Merino (SAMM) breeds. Udders were scored subjectively on a 1-5 scale (1 - udder intact and 5 - udder damaged severely) and ticks were counted on three locations. The body sites counted were the head and thoracic limb (HTLTC), udder-pelvic limb (UPLTC) and perineum-breech-tail (PBTTC). These counts were also totaled for a total tick count (TTC). Reproduction traits were number of lambs weaned per ewe lambed and total weight of lamb weaned per ewe lambed. Udder health scores of NA ewes were lower than those of Dorpers, which in turn had lower scores than SAMM ewes. NA ewes had lower values for HTLTC, UPLTC and TTC than the commercial breeds, but higher values for PBTTC than Dorpers. Heritability estimates amounted to 0.26±0.04 for HTLTC, 0.53±0.04 for UPLTC, 0.07±0.06 for PBTTC, 0.44±0.06 for TTC and 0.61±0.03 for udder health score. Animal permanent environment also affected PBTTC (0.14±0.07). Significant genetic correlations were found between the HTLTC and UPLTC (0.47±0.10), UPLTC and udder health score (0.52±0.07), HTLTC and UPLTC (0.24±0.11) as well as UPLTC and PBTTC (-0.44±0.11). Heavier ewes had higher UPLTC (0.38±0.09), TTC (0.33±0.09) and impaired udder health (0.21±0.08). Udder health scores and tick counts at all sites were not related to reproduction traits. The indigenous NA breed outperformed the commercial breeds with lower values for HTLTC, UPLTC, TTC and a better udder health score. Mechanisms contributing to the better performance of the NA breed under pastoral conditions and the scope for selection for tick tolerance within breeds should be studied further.