Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

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The objective of this work was to define the effects of dietary energy intake on broiler fat deposition and metabolism. Fatty broilers are one of the major problems in the broiler industry. The effects of changing calorie to protein (Cal/Pr) ratios, and the addition of cellulose or dried distiller's byproduct (DDBP) in the diet, on abdominal fat deposition, liver lipogenesis and glucose oxidation and broiler performance indicated that the mean body weight of broilers fed narrower Cal/Pr ratio diets (124 and 143 for starter and grower, respectively) were lower (P<.01) than broilers fed diets with mid-Cal/Pr ratios (138 and 160) and wide Cal/Pr ratios (147 and 171). Feed conversion was better (P<.01) for broilers fed the diet with wide Cal/Pr ratio than the broilers fed the diet with narrow Cal/Pr ratio. Abdominal fat deposition increased (P<.001) with wide Cal/Pr ratio than narrow Cal/Pr ratio. No significant differences were found in in vitro liver lipogenesis and glucose oxidation when Cal/Pr ratio was widened. Mean body weight, feed conversion and abdominal fat levels of broilers fed 5% cellulose or 10% DDBP diets were not different when compared to broilers fed diets with the same Cal/Pr ratio without these two feed ingredients. The time-course of the deposition of abdominal fat fitted a negative exponential growth curve. The data also indicated that the highest potential for abdominal fat deposition was during the first two weeks of age. When the feed intakes of broilers were restricted for a 6 day period beginning at 1, 2, 3 and 4 weeks of age, the feed efficiencies of all the restricted broilers were significantly improved compared with broilers fed ad libitum. No significant differences were observed in mean body weight between the different treatments. The percentage of abdominal fat in broilers restricted-fed starting either at 1 or 2 weeks old for a 6-day period were lower (P<.05) than broilers fed ad libitum. Feed restriction from days 7 to 12 reduced the adipocyte size but not the number. Feed restriction decreased (P<.05) lipogenesis at 2 and 8 weeks of age. No significant effects were found in lipolysis between the restricted and ad libitum-fed broilers. These studies demonstrate that early feed restriction (days 7 to 12) reduced abdominal fat deposition which is attributed to the reduction in the adipocyte size. Smaller size adipocyte resulted from decreased activity of lipogenesis. / Graduation date: 1991