Last update: April 7, 2011 11:59:49 AM E-mail Print



MA Snyman & M.J. Herselman

Grootfontein Agricultural Development Institute, Middelburg, 5900

J.A.N. Cloete

Carnarvon Experimental Station, Carnarvon, 8925


It is a  fact that  fat-tailed sheep carcasses are  labelled at the abattoirs and prices of up to R3-00 per kg less are paid for fat-tailed carcasses when compared to other non fat-tailed carcasses of the same fat grade. At the Departmental Experimental Station at Carnarvon, a Namaqua Afrikaner and a Dorper flock are run under similar management conditions. The lambs of these two flocks run together from weaning at the age of 100 days. The purpose of this study was to evaluate the carcass quality of Namaqua Afrikaner ram lambs by comparing it to those of Dorper ram lambs. Thirty-one Namaqua ram lambs and 42 Dorper ram lambs born during August-September 1994 were slaughtered as soon as they reached a live body weight of approximately 42 kg. All lambs were slaughtered directly from the veld and received no supplementary feeding. It should be noted that the rainfall for the period August 1994 to July 1995 was 106 mm, compared to the average annual rainfall of 210 mm. This lead to relatively poor grazing conditions, as will be evident from the relatively high slaughter ages in both breeds. The same measurements as those taken in the National Lamb Carcass Competition were recorded on each carcass. The data were analysed with Least-squares-mean procedures, and fixed effects for breed and rearing status as well as a covariate for slaughter weight were included in the model. The following results were obtained for Namaqua Afrikaner and Dorper ram lambs respectively (in those traits followed by an * significant differences (P<0.01) were observed between the two breeds) : age at slaughter (301.88±3.49 days and 293.63±3.63 days); average daily gain from birth to slaughter age (127.77±1.34 g/day and 131.35±1.40 g/day); carcass weight (19.11±0.23 kg and 18.48±0.23 kg); dressing percentage* (51.90±0.57 % and 48.51±0.59 %); b1-measurement* (39.53±0.23 cm and 35.06±0.24 cm); b2-measurement* (52.47±0.27 cm and 47.90±0.28 cm); leg circumference* (65.52±0.28 cm and 69.15±0.29 cm); carcass length* (111.06±0.43 cm and 105.43±0.45 cm); v1* (13.94±0.76 mm and 7.41±0.80 mm); v2* (11.43±0.64 mm and 5.29±0.67 mm); v3* (9.57±0.55 mm and 5.62±0.57 mm); v4 (2.50±0.25 mm and 2.47±0.26 mm); v5* (0.75±0.09 mm and 1.08±0.09 mm); fat distribution over the eye muscle* (2.19±0.12 and 3.60±0.12); conformation score* (1.93±0.44 and 5.88±0.46); abdominal cavity fat score (4.58±0.17 and 4.50±0.18). The weight of the fat tails of the Namaqua Afrikaner lambs ranged from 0.8 kg to 3.0 kg, with an average of 1.8 kg. The results indicate that Namaqua Afrikaner lambs have a higher dressing percentage than Dorper lambs and their carcasses are longer with more fat in the posterior parts and less fat in the anterior parts. Dorper carcasses have a more square conformation, compared to the narrower carcasses of the Namaqua Afrikaner. This may in part explain the consumer resistance against fat-tailed carcasses, as the more expensive cuts are not as attractive as those of Dorper carcasses.




Congress DAB-SASAS, Pilansberg, 1-4 October