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Apart from slight changes in starch contents, maize grain quality was largely unaffected by drying at different temperatures between 85° and 105°C. Over a feeding period of 28 days feed intake was increased (P < O.O5) as a result of heat-treating the maize up to 95°C. Including a microbial enzyme, Avizyme l500, resulted in an increase (P < O.O5) in final body weight of chicks but there was no response when growth was assessed at an earlier age. Over the entire feeding period, feed conversion efficiency (FCE) declined (P < O.O1) with increasing oven temperature, regardless of supplementation with the microbial enzyme. The weight of visceral organs, protein content and activities of pancreatic and jejunal digestive enzymes were unaffected by grain heat treatment or microbial enzyme supplement. The ileal digestibility of calcium was reduced (P < O.O1) on diets based on fresh maize and maize that was oven-dried at 105°C. Heat-treatment improved (P < O.O5) the ileal digestibility of phosphorus in chicks on the diets without the enzyme supplement. No effects of grain heat treatment or microbial enzyme supplementation was observed on ileal digestibility of energy, protein, Ca and amino acids. The results indicate some variations in grain quality as a result of heat treatment but the differences were not significant enough to stimulate major responses to the microbial enzyme. |
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