Crossbred lambs better?

Rising input costs and low market prices are forcing sheep producers to produce more meat and wool per hectare
Issue date 26 October 2007

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Rising input costs and low market prices are forcing sheep producers to produce more meat and wool per hectare. According to Jasper Cloete, an animal production specialist from the Cape Institute of Agricultural Training at Elsenburg, crossbreeding is a valuable tool which allows producers to cash in on short-term market tendencies, “Crossbreeding is used with great success in the pork and beef industries. It allows producers to take advantage of hybrid vigour and sexual dimorphism and can increase offspring’s growth and survival rates by 10%,” Cloete told delegates at a Red Meat Producers’ Information Day hosted by Van Rensburgs Foods and Nova Feeds in George in the Western Cape. Realistic expectations C loete has compared the impact of crossbreeding different ram breeds – Dormers, Ile de France, SA Mutton Merino, Merino Landsheep, Suffolk and Dorpers – with Merino ewes, on lamb growth, carcass composition and meat quality. He said none of the ram breeds performed significantly better than the others and crossbreeding didn’t impact significantly on meat quality. When selecting rams for crossbreeding, farmers should therefore look at other factors such as availability of rams and wool contamination. D ue to hybrid vigour, however, crossbred lambs were ready for slaughter at a younger age than control lambs produced from Merino rams. On average, purebred Merino lambs were slaughtered 40 to 50 days later than crossbred lambs, which were also 9% to 11% heavier at slaughter. Less fatty Dorpers P urebred Merino and Merino Landsheep had lower fat cover than crossbred lambs. Dorper and Dormer crossbred lambs had the highest fat cover at the 13th rib and between the third and fourth lumbar vertebrae. I n another study Cloete aimed to use crossbreeding to produce heavier lambs with less fat, since pure Dorper lambs often gain too much fat at a young age. He crossbred ewes with Ile de France, Mutton Merino and Merino Landsheep rams and found that, irrespective of the cross-selection, cross lambs had around 20% less fat than pure Dorper lambs. The meat from the Mutton Merino x cross lambs was significantly more tender than that of any of the other cross selections or the pure bred lambs. pointed out, however, that more research is needed to determine the impact of crossbreeding on meat quality. Hybrid vigour versus breed strength A nother research trial compared the use of Dormer and rams as terminal crosses on an Mutton Merino (ram) x Merino (ewe) cross. The offspring’s performance was compared with the performance of pure Merinos and Mutton Merinos. loete found that hybrid vigour led to higher lamb percentages – slaughter lambs per cross ewe were around 116%, compared to 107% for the Mutton Merinos and 90% for Merinos. The average weight of slaughter lambs was also higher for the cross ewes (44,2kg) than for the Mutton Merinos (42,7kg) and the pure Merinos (32,9kg). But Cloete warned that crossbreeding shouldn’t be used at the expense of genetic improvement in specific breeds, which “helps preserve and improve specific traits associated with a specific breed. Producers mustn’t find themselves in a situation where they’ve crossbred all their ewes and have no replacement animals in the herd,” he said. Contact Jasper Cloete on (021) 808 5489. |fw