Correlations of subjectively assessed fleece and conformation traits with production and reproduction in Afrino sheep

Data used for this study were collected on the Carnarvon Afrino flock from 1986 to 1998, and include data records on several subjectively assessed traits, body weight and fleece traits of 3291 animals, the progeny of 127 sires and 772 dams. Reproduction data of 686 ewes born from 1986 to 1997 were also included. The heritabilities of and genetic and phenotypic correlations among the subjectively assessed traits were estimated, as well as the genetic and phenotypic correlations of these traits with body weight, objective fleece traits and reproduction. Heritability estimates for the various subjectively assessed traits ranged from 0.06±0.02 for straightness of the top line to 0.51±0.04 for softness of fleece. Positive genetic correlations, ranging from 0.33±0.18 to 0.80±0.06 were estimated amongst the conformation traits head, front quarters, top line and hocks. High genetic correlations were estimated among the subjectively assessed fleece traits and fibre diameter, where animals with lower fibre diameter had softer fleeces, better crimp definition, their fleeces were more even, less dense and had higher creeping belly scores (the extent to which belly wool tends to creep up the side into the fleece). Estimated genetic correlations between the subjectively assessed fleece traits and reproduction were variable in sign and magnitude. The most important of these is the unfavourable genetic correlation (-0.33±0.23) between creeping belly and reproduction. The conformation traits had moderate to high genetic correlations with body weight at all ages. Of the subjectively assessed fleece traits, creeping belly score had the highest genetic correlation with body weight, ranging from -0.26±0.10 for weaning weight to -0.38±0.07 for 15-month body weight. No noteworthy phenotypic correlations were discernable between the reproductive traits and any of the subjectively assessed traits. Of the objective fleece traits, only fibre diameter had some significant phenotypic correlations with the subjectively assessed fleece traits. These were similar in sign, but smaller in magnitude than the corresponding genetic correlations. It is concluded that, with the exception of two or three traits, the subjectively assessed traits would not be negatively influenced when selection is based on the economically important production traits. It is, however, important that selection priorities be based on economic values of the traits. South African Journal of Animal Science Vol.32(2) 2002: 88-9

A comparison of leather properties of skins from ten different South African sheep breeds

(South African J of Animal Science, 2000, 30, Supplement 1: 129-130

The impact of DNA parentage verification on breeding value estimation and sire ranking in South African Angora goats

Pedigree integrity plays a crucial role in the achievement of genetic progress in livestock selection programmes. DNA marker-based parentage testing has become a useful tool for amending inaccuracies in on-farm pedigree records. In the current study, the extent of inaccurate and incomplete pedigree records was quantified in 381 South African Angora goats using a 12 microsatellite markers. Eight half-sib families with a total of 317 Angora kids,40 kids with unknown sires and an additional 16 putative sires were included in the study.14.3% of the on-farm pedigrees were amended, including incorrect (according to the DNA verification) or incomplete records. Estimated breeding values (EBV) for fleece traits (fibre diameter and fleece weight) as well as body weights (birth weight and weaning weight)were calculated for 21 sires using ASREML, firstly for the breeder’s recorded pedigree and secondly for the DNA-verified pedigree. An overall greater effect was observed in bodyweight traits than in fleece weight traits with regard to sire EBVs and the ranking there of. The significant change realised in sire ranking after DNA marker-based pedigree verification emphasises the importance of pedigree integrity in maximising selection accuracy for the production of the highest quality mohair clip in the South African Angora goat industry.The International Foun-dation for Science, Stockholm, Sweden through a researchgrant (B/4998-1). This work is based on the research sup-ported in part by a number of grants from the NationalResearch Foundation of South Africa (UID: 78566 (NRF RISPgrant for the ABI3500)).http://www.elsevier.com/locate/smallrumreshb201

Quantitative trait loci associated with pre-weaning growth in South African Angora goats

This study aimed to identify chromosomal regions associated with genetic variation in preweaning growth traits in Angora goats. A genome-wide scan was performed by genotyping 1042 offspring from 12 half-sib families using 88 microsatellite caprine markers covering 1368cM. Phenotypes were recorded at birth (BW) and weaning (WW) and analysed using GridQTL software. A total of six putative QTL were detected on six different chromosomes, all at chromosome-wide significance level. Four QTL were identified for BW on CHI 4, 8, 17 and 27 and two QTL for WW on CHI 16 and 19. QTL effects ranged from −0.32 to 0.25 in units of residual standard deviation in different families. Some of these QTL correspond to chromosomes where QTL associated with growth have been identified in other species. These chromosomal segments hold potential to influence weight gain in young goats.http://www. elsevier.com/locate/smallrumreshb201

The effect of water intake prior to blood sampling on packed cell volume in sheep : short communication

The effect of water intake prior to blood sampling on subsequent packed cell volume (PCV) was investigated in ewe lambs (8 months of age) of the Dohne Merino, Merino and Letelle flocks at Grootfontein Agricultural Development Institute. On the afternoon of the day before the experiment was conducted, a blood sample for a baseline PCV value (R) was taken from each animal. The following day, 15 ewes of each breed (n=45) were dosed with 1 litre of water and another 15 of each (n=45) were used as a control. Blood samples for PCV were taken concurrently for both the control and water treatment groups before the dose (0), and at 15, 30 and 60 minutes after dosing . PCV were subsequently determined with the microcapillary centrifuge technique. Baseline PCV of Letelle ewes was higher (32.4 + 0.6) than that of the Dohne Merino (29.7 + 0.6) and Merino (28.7 + 0.6) ewes. Furthermore, recovery rate at 30 minutes after treatment also differed among breeds. Although there were significant differences between the control and water treatment groups at R and 0 minutes, which were probably due to inherent animal differences, there were no significant differences between PCV of the 2 groups during the remainder of the experimental period. Overall it can be concluded that water intake before blood sampling for the determination of PCV has no significant effect on haematocrit. Differences among breeds were more pronounced than those between treatment groups

Productive performance of hair and wool type Dorper sheep under extensive conditions

The reproductive performance, growth, slaughter traits, and several conformation characteristics in Dorper sheep (hair and wool types) were evaluated under extensive conditions in the north-western Karoo region of South Africa. From 1993 to 2000, lambs of hair (n=1070) and wool (n=1044) type Dorper sheep, and corresponding reproductive records from 872 and 874, respectively, were analysed. There was no significant differences between hair and wool type lambs for body weight from 42 days till 12 months of age, and for pre- or post-weaning growth rate. The analysis of conformation tend to suggest that the hair type lambs were blockier with shorter legs, compared to the leggier appearance of the wool type lambs. This is also evident from the longer carcass length (108.5 vs. 107.2 cm) and hind leg length of wool type lambs compared to hair type lambs. With regard to other carcass traits, wool type lambs had heavier carcasses (19.6 vs. 19.2 kg) and higher dressing percentage (49.9 vs. 49.0%), though, fat measurements and carcass grades were similar. The ewes of the hair type were heavier at mating than wool type (57.4 vs. 56.4 kg). No differences were, however, observed for percentage of ewes lambed, lambs born, lambs weaned, survival rate of lambs or kg lamb produced per ewe per year. It was concluded that the economically important reproduction and growth traits were similar between the hair and wool types of Dorper sheep. Differences that do occur in some conformation and carcass traits will not effect the economic realisation from the different types