Last update: November 22, 2010 11:03:57 AM E-mail Print

 

THE EFFECT OF DOCKING ON GROWTH, CARCASS QUALITY, FAT DISTRIBUTION

AND REPRODUCTIVE PERFORMANCE OF NAMAQUA AFRIKANER SHEEP

 

1M. A. Snyman, M van Heerden & B.R. King, 2J.A.N. Cloete, 3M.L. Jonker

 

1Grootfontein Agricultural Development Institute, P/Bag X529, Middelburg, 5900, South Africa

2Carnarvon Experimental Station, P.O. Box 98, Carnarvon, 8925, South Africa

3Vaalharts Research Station, Private Bag X9, Jan Kempdorp, 8550, South Africa



The aim of this study was to investigate the effect of docking of Namaqua Afrikaner lambs on growth performance, slaughter traits, fat distribution over the carcass and reproductive performance. The Namaqua Afrikaner ewe flock (105 ewes) of the Carnarvon Experimental Station was used for this study. In April 1997, thirty additional ewes were mated. The lambs of these ewes, born during September 1997, were docked two days after birth with elastrator bands. Ram lambs were slaughtered at 40 kg body weight and compared to their counterparts with intact fat tails. The ewe lambs were allowed to reproduce for three lambing opportunities and their reproductive performance was compared with that of the intact 1997-born ewes over the same period. There was no difference in birth weight of docked and intact lambs, which was to be expected. However, intact lambs were heavier (P<0.05) than docked lambs at 42-days of age. From weaning till 12 months of age, no difference in body weight occurred between groups. Docked lambs had significantly lower carcass weights than intact lambs (19.5±0.5 kg vs. 20.8±1.2 kg). This was due to the lower dressing percentage (48.7±1.0 % vs. 51.9±1.2 %) of docked lambs. Weight of the fat tail/fat around the tail differed between intact and docked lambs (1748±113 g vs. 557±96 g). It was obvious that docked lambs still accumulated some fat around the tail. There was no significant difference in fat distribution over the carcass between docked and intact carcasses. Intact ewes had a higher body weight than docked ewes. Docked ewes had a 6 % higher conception rate, a 9 % higher lambing percentage and a 16.5 % higher weaning percentage than intact ewes. Docked ewes also had a lower percentage of stillbirths and their lambs had a higher survival rate from birth to weaning. Individual weaning weights of lambs did not differ between docked and intact ewes. From the results of this study it is evident that docking of Namaqua Afrikaner lambs after birth did not influence growth rate, carcass traits or fat distribution over the carcass. Ewes that have been docked tended to have a higher reproductive rate than intact ewes, most probably due to rams being better able to service docked ewes. There was no evidence that docking of Namaqua Afrikaner ewes influenced their hardiness during the trial period.