FACTORS AFFECTING RYE (SECALE CEREALE L.) UTILIZATION IN GROWING CHICKS. II. THE INFLUENCE OF PROTEIN TYPE, PROTEIN LEVEL AND PENICILLIN

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Abstract
Three experiments were conducted to evaluate the influence of protein type, protein level and penicillin on the utilization of rye by growing chicks. The effects of the following dietary ingredients, respectively, were studied: meat meal or fish meal in rye or wheat diets containing 18 or 26% crude protein, increasing levels of penicillin in rye diets containing meat meal or fish meal, and two levels of penicillin in rye or wheat diets containing meat meal or fish meal. The results indicate that the type (quality) and level (quantity) of the dietary protein plus penicillin affected chick performance. As a dietary ingredient, rye consistently depressed chick growth and the efficiency of feed utilization relative to wheat; these adverse effects were accentuated by feeding rye diets containing a low level of a lower quality protein. However, supplementation of these diets with penicillin or a higher quality protein markedly alleviated these effects. The maximum improvement in chick performance was achieved with rye diets containing fish meal plus penicillin compared to those containing meat meal without penicillin; these relative changes for rye and wheat diets, respectively, were: +121 and +26% for weight gain; +35 and +5% for feed intake, −39 and −17% for feed:gain, +11 and −1% for dry matter retention and +83 and +30% for protein retention. Results would suggest that rye contains factor(s) that reduce(s) the utilization of nutrients, particularly protein. Penicillin supplementation appears to have a protein-sparing effect, particularly when the dietary protein quality and/or levels are suboptimal.