GRAIN SCREENINGS AS A DIETARY COMPONENT FOR PIGS AND SHEEP. II. ANIMAL UTILIZATION

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The digestibility of four types of grain screenings, No. 1 screenings, rapeseed screenings, mixed feed oats and refuse screenings was measured with pigs, rats and sheep. For the pig diets, hammermilled screenings replaced 60% of a complete basal diet, with the exception of the rapeseed screenings, where replacement level was 10% (hammermilled) and 20% (whole). Digestibility values were determined by difference. In the rat diets screenings were incorporated to provide 1.5 g N 100 g−1 dry matter (DM) and the biological value (BV) of the protein was also measured. In the sheep diets, all screenings except rapeseed were provided as the sole dietary component, with the No. 1 feed screenings and the mixed feed oats pelleted without prior grinding and the other screenings ground before pelleting. For rapeseed screenings, incorporation in the sheep diets was at a level of 30%. For No. 1 screenings, apparent digestibility of organic matter (OMD) and nitrogen (ND) for pigs was 82.3 and 83.2%, respectively; BV for rats was 77.4%, while OMD and ND for sheep was 73.9 and 72.7%, respectively. For rapeseed screenings, OMD and ND for pigs for the hammermilled screenings were 46.1 and 50.7%, respectively, and for the whole screenings were 30.3 and 11.5%, respectively. Biological value (rats) was 80.0%, while for sheep OMD and ND it was 63.9 and 77.4%, respectively. For mixed feed oats, OMD and ND for pigs were 63.8 and 82.6%, respectively; BV (rats) was 61.1% and OMD and ND for sheep were 64.2 and 73.4%, respectively. For refuse screenings, OMD and ND for pigs were 63.8 and 65.4%, respectively; BV (rats) was 83.8%, while OMD and ND for sheep were 59.9 and 65.3%, respectively. Number 1 feed screenings are of a high nutritive value and are suitable as a grain for both pigs and sheep. Unprocessed rapeseed screenings are unpalatable for pigs with both dry matter and protein poorly utilized. With sheep, pelleted rapeseed screenings are readily accepted, and the nitrogen is well digested. If mixed feed oats are ground, protein is well digested by both species although dry matter digestibility is low. Refuse screenings appear to be suitable only for ruminant diets. Key words: Grain, wheat, barley, oats, rapeseed, screenings