Abstract
This research sought to develop a mathematical model to predict the growth and feed intake of Boer goat kids destined for slaughter. Data were collected from castrated kids that were housed in individual pens and fed diets that varied in energy content (11.3, 12.0, and 12.7 MJ metabolizable energy (ME)/kg feed). Growth and feed intake were monitored weekly for 20 weeks, from the time that the kids weighed 22.2 ± 3.5 kg until they were slaughtered at 48.3 ± 0.8 kg. The linear equation (bodyweight = 0.202 age – 5.241 (R2 = 0.84)) was found to predict the growth of kids between 126 and 266 days old. Correlations between expressions of intake and bodyweight were evaluated, cumulative feed intake and bodyweight being most highly correlated (r = 0.93). Linear models were developed to predict cumulative feed intake from bodyweight for goats fed each diet. Regression coefficients were compared between diets, with the slope of the equation for goats on the low energy diet (6.74 ± 0.25) being greater than that of the medium (5.80 ± 0.23) and high energy diets (5.82 ± 0.23). This indicates that goats on the medium and high energy diets gained weight more efficiently than those on the low energy diet. The results from this study can be used by goat producers to predict the growth and intake of goats and determine the ideal feedlot finishing period for optimal productivity.______________________________________________________________________________________Keywords: cumulative intake, dietary energy, modelling
Highlights
Small stock production is of great importance for the production of wool, leather, red meat and dairy products for human use (Sayed, 2011)
On entry to the feedlot, the kids were stratified by bodyweight and within strata were randomly allocated to one of three finishing diets, which varied in metabolizable energy content (Table 1), namely a low (11.3 MJ ME/kg feed), medium (12.0 MJ ME/kg feed) and a high energy diet (12.7 MJ ME/kg feed)
This study is not aimed at the overall production characteristics, but at changes in weight and feed intake of Boer goat kids being fed for slaughter in order to develop prediction models that can be integrated in decision support systems
Summary
Small stock production is of great importance for the production of wool, leather, red meat and dairy products for human use (Sayed, 2011). Small stock production in Africa has increased tremendously since 1993. In 2016 South Africa had an estimated 20.4 million head of sheep and 1.88 million goats (DAFF, 2017). Sheep and goat production in South Africa varies from free range to extensive and intensive production systems on commercial farms, with a large sector consisting of communally herded livestock. The versatility of the small stock industry is made possible with a wide selection of breeds that are suited to specific environmental and production conditions (Visser et al, 2004; Schoeman et al, 2010). Increases in South African mutton and lamb meat and chevon (meat from goats with fewer than two permanent incisors) prices (DAFF, 2017) have resulted in farmers finishing lambs and kids in feedlot systems to achieve a desirable slaughter weight at an earlier age with an optimal degree of fatness. To ensure efficient optimal levels of production, an understanding is needed of the growth trends and feed consumption of slaughter kids
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