Author
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Rosebrough, Robert |
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Submitted to: Feedstuffs
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/8/2003 Publication Date: 12/8/2003 Citation: Rosebrough, R.W. 2003. Dietary protein and sex effects in the young broiler. Feedstuffs. 74(11):12. Interpretive Summary: Excess fat production by the modern broiler chicken presents a two-fold problem. The consumer has health concerns about the link between cardiovascular disease and dietary fat. The producer would like to produce more lean meat rather than fat condemned at the processing plant. Historically shifts in metabolism have resulted in dietary fat being merely shunted to replace that synthesized from other feed ingredients. We have found that altering feeding regimens and dietary crude protein in the broiler will cause permanent changes in fat synthesis and storage, such that dietary fat will not be shunted to body fat stores. The present study was designed to determine if dietary protein elicited changes in intermediary metabolism and if changes resulted from alterations in the expression of genes coding regulatory proteins. Although increasing dietary protein decreased fat synthesis by the broiler, gene expression did not accompany this decrease unless the diet contained a very high level of protein. Modest increases in dietary protein will decrease lipid synthesis without affecting gene expression. Technical Abstract: Male and female broiler chickens growing from 7 to 28 days were fed diets containing 12, 21 or 30% crude protein to determine sex x protein interactions affecting growth and intermediary metabolism. Results of the present study demonstrated a continued role for protein in the regulation of metabolism in the chicken. It was of interest to note that increases in growth of the modern chicken over the past 15 to 20 yr. have occurred while feeding lower levels of dietary protein. In turn, this response has also been accompanied by an increase in lipogenesis. It could be suggested that one of the byproducts of this selection process has been a favoring of appetite as efficiencies of feed utilization have remained unchanged. The data also demonstrate the validity of sex-separate rearing conditions for at least the early to mid starter period. Sex separate rearing, in our hands, means feeding higher protein diets to males than to female broiler chickens. Regretfully, sex-separate responses to dietary protein could not be explained by the usual measurements of intermediary metabolism we use to describe adaptations to diets. |
