Author
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Rosebrough, Robert |
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Submitted to: Feedstuffs
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/1/2002 Publication Date: 5/1/2003 Citation: Rosebrough, R.W. 2003. Dietary protein and the modern turkey poult: An update on intermediary metabolism. Feedstuffs. 74(5):17. Interpretive Summary: The modern turkey has been extensively selected for breast muscle growth. This selection practice is quite different from the multi-factorial approach used in the broiler industry. While metabolism in the modern broiler will respond to changes in dietary energy, protein and amino acids, little is known about dietary influences on in vitro metabolism in the turkey other than what was published over 20 yr. ago. This summary of results obtained over almost 20 yr. will elucidate some of the changes that have occurred in both growth and intermediary metabolism as selection pressures on the modern turkey have intensified.Results of the present study demonstrated a continued role for protein in the regulation of metabolism in the turkey. It was of interest to note that increases in growth of the modern turkey 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. Technical Abstract: Turkey poults growing from 7 to 28 d were fed diets containing 24 or 30% protein (1980) or 18, 24 or 30% protein (1995) to determine dietary effects on growth and intermediary metabolism. All diets contained 58% of the total energy as carbohydrate so that effects could be attributed solely to protein content. At both intervals, 30% crude protein resulted in the greatest weight gain and feed consumption. In vitro lipogenesis and malic enzyme activity were inversely related to dietary crude protein. In contrast, increasing dietary crude protein increased the activities of both aspartate aminotransferase and isocitrate dehydrogenase. Values for plasma triglycerides were higher and uric acids were lower when lower levels of crude protein are fed to the modern turkey. Both parameters can be taken as valid indicators of changes in body fat and protein stores, respectively. Results of these studies demonstrate a continued and accentuated, role for protein in the regulation of turkey metabolism. Results also indicate that selection practices over the last 15-20 yr. have resulted in improved growth rates on lower protein diets and increased lipid synthetic potential. |
