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Abstract
An increasing number of producers opt to finish their lambs in on-farm feedlots. Therefore, detailed production information is required to implement precision finishing of lambs of different genotypes. Precision finishing monitors growth, feed intake and efficiency to optimize management. In this study, feedlot production characteristics of Dohne Merino, Dormer, Dorper, Meatmaster, Merino, Namaqua Afrikaner, and South African Mutton Merino (SAMM) lambs were evaluated. The lambs were reared in a feedlot and fed a diet with 10.41 MJ metabolizable energy (ME)/kg feed and 19.06% crude protein. Feed intake and body weight were recorded weekly from an initial weight of 30 kg until they had the subcutaneous fat cover needed to produce an A2 carcass. Subcutaneous fat was measured on the Longissimus lumborum muscle with an ultrasound scanner. Dorper, Meatmaster and Namaqua Afrikaner had the shortest rearing periods in the feedlot, and were market ready at a lower live weight (P <0.05). As a result, these lambs consumed less feed in the feedlot. Namaqua Afrikaner and Merino lambs were least efficient: 7.08 and 5.63 kg feed/kg gain, respectively. Dohne Merino, Dormer, Dorper, and Meatmaster rams and Dorper ewes were more efficient; approximately 3.58 kg feed/kg gain. Dohne Merino and Dormer rams had the highest growth rates: approximately 465 g/day. The end weights described in this study could be used as an indication for producers of the ideal slaughter weights for breeds of different maturity types.Keywords: average daily gain, fat deposition, feed efficiency, rearing period
Highlights
Vast semi-arid and arid regions in South Africa and Namibia are unsuitable for most agricultural practices, with the exception of extensive sheep production, because sheep are well adapted to these conditions (Brand, 2000)
The length of the feeding period generally did not differ between ewe and ram lambs (P =0.574), Namaqua Afrikaner ewe lambs spent a longer time in the feedlot than the corresponding ram lambs (39 and 18 days, respectively) (P
Merino lambs were fed for the longest time, but the time on feed for Dohne Merino, South African Mutton Merino (SAMM), Dormer required a similar time on feed to produce an A2 carcass
Summary
Vast semi-arid and arid regions in South Africa and Namibia are unsuitable for most agricultural practices, with the exception of extensive sheep production, because sheep are well adapted to these conditions (Brand, 2000). The most popular breeds in commercial production systems, based on the number of weaning weight records, are Merino, Dohne Merino and Dorper, followed by the SAMM and Dormer (Cloete & Olivier, 2010). The Meatmaster is a more recent composite fat-tailed breed, with predominantly Damara lineage, which was developed for commercial lamb production in extensive arid conditions (Peters et al, 2010). The Namaqua Afrikaner is regarded as an unimproved indigenous fat-tailed breed with low mature weight, which tolerates harsh environmental conditions (Qwabe et al, 2013). These breeds all vary in their growth and maturity characteristics
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