Abstract
A study was conducted to establish non-genetic factors affecting growth and carcass traits in Large White and Landrace pigs. This study was based on 20 079 and 12 169 growth and 5 406 and 2 533 carcass data collected on performance tested pigs between 1990 and 2008 from Large White and Landrace breeds respectively. The traits analyzed were backfat thickness (BFAT), test period gain (TPG), lifetime gain (LTG), feed conversion ratio (FCR), age at slaughter (AGES), lean percentage (LEAN), drip-free lean percentage (DLEAN), drip loss (DRIP), dressing percentage (DRESS), carcass length (CRLTH) and eye muscle area (AREA). Significant effects were determined using PROC GLM of SAS. Herd of origin, year of testing and their interaction significantly affected all traits. Most traits were not affected by season of testing in both breeds, while all traits in both breeds were significantly affected by sex. Testing environment (station, farm) affected all growth traits except for LTG. Backfat thickness and AGES increased with increasing total feed intake, while other traits decreased as total feed intake increased. Improved test centre management did not compensate for pre-test underperformance. Castrates produced higher carcass yields of lower quality than females, while performance testing showed the best results when done at testing centres. This study showed the importance of adjusting for fixed effects when performing genetic evaluations in the two pig populations.Keywords: Carcass traits, growth traits, environmental effects, Large White, Landrace, swine
Highlights
The value of a meat animal is realized when its product is marketed and expressed relative to the input costs incurred
Pre-test environment has an effect on growth and carcass attributes (Beattie et al, 2000; Gentry et al, 2002; 2004; Hansen et al, 2006). These results suggest that differences in growth performance may be due to differences in management practices applied on different farms
The purpose of this study was to evaluate the non-genetic effects on growth and carcass traits within the two major South African commercial pig breeds
Summary
The value of a meat animal is realized when its product is marketed and expressed relative to the input costs incurred. Valuable pigs are the ones which, for each unit of food energy, waste least in such processes as digestion and physical activity, and retain most by favouring conversion of metabolizable energy to lean than conversion to fat tissue (Webster, 1977). This has desirable implications on enterprise profit, as feed constitutes a large portion (60 – 70%) of pig enterprise costs (Hoque et al, 2007). Pig characteristics that are positive for profitability, are high growth rate, food conversion ratio and low carcass fatness (McPhee & MacBeth, 2000). Improvement has been achieved in some breeding programmes through selection for lean growth rate (McPhee et al, 1991; Cameron, 1994)
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