Effect of production system on the growth rate, carcass characteristics and carcass composition of Dorper lambs
An investigation on the effect of production system on growth rate, carcass characteristics and carcass composition of Dorper lambs was carried out under South African conditions. The study involved sixty lambs which were divided into two production/feeding groups (feedlot (FL) vs. free-range (FR)) at weaning. Each group consisted of 10 lambs from three gender classes (ewes, rams and castrates). The FL-lambs were fed a commercial pelleted ration while the FR-group grazed natural pastures. The production system x gender interaction indicated that male lambs (castrates and rams) grew twice as fast as ewes under FL-conditions. Gender groups were less pronounced in FR-lambs. FL-lambs produced heavier carcasses, higher dressing percentages and greater carcass fatness levels than FR-lambs. Ram lambs attained heavier slaughter weights and produced heavier carcasses than ewe lambs with castrates being intermediate. Production system did not have an effect on intramuscular lipid concentration, barring a tendency in the Biceps femoris muscle. It was concluded that the FL-diets were generally associated with better lamb growth rates, greater carcass fatness and an improved dressing percentage. Although animal performance was generally improved in the more intensive FL-system, it was also concluded that discerning consumers will likely prefer the more natural (and therefore more ethically acceptable) FR-meat.