The replacement of maize meal with sodium hydroxide treated wheat straw in growth diets for lambs

Author: H.S. Hofmeyr, T.H. Jansen & C.Z. Roux
Year: 1982
Issue: 2
Volume: 12
Page: 113 - 118

The possible replacement of maize with NaOH-treated straw in growth diets of lambs were tested. Four diets with 43; 29; 14 and 0% maize grain and 0; 24; 48 and 72% treated straw were formulated in such a way that the concentrate : roughage ratio changed from 65:35 to 28:72 while the calculated energy digestibility for all 4 diets remained at 68%. Maize straw was used with the maize grain to bring down the energy content. Digestibility and metabolizability of the energy in the diets were tested with 4 mature wethers in a 4 x 4 Latin square design experiment at maintenance level of intake. Faecal energy excretion increased significantly with increased level of treated straw, probably due to an underestimation of the digestibility of the maize straw. Urinary energy dropped with increased levels of treated straw, but the ratio of ME:DE remained constant at 0,79 due to a tendency for increased methane production with increased treated straw level. Voluntary feed intake, growth and body composition on the 4 diets were tested with Dohne merino lambs averaging 27,5 kg. Forty-eight lambs were divided into 4 groups, each group receiving one of the diets ad libitum. With 7 day intervals, one animal per group was slaughtered and analysed for body and carcass DM-, protein- and fat content. Body mass and feed intake of the growing lambs were measured weekly. Although DM-intake increased highly significantly with increased treated straw levels, the ME-intakes of the 4 groups were the same. Body mass and carcass mass as well as body and carcass proteins did not differ between groups. DM and fat gains of body and carcass decreased significantly with increased treated straw

Keywords: chemical treatment, growth diets, lambs, maize meal, NaOH, wheat straw
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