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METABOLISM AND NUTRITION |

* Department of Biosystems, Katholieke Universiteit Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium; and
UR83 Recherches Avicoles, Institut National de la Recherche Agronomique, F-37380 Nouzilly, France
1 Corresponding author: johan.buyse{at}biw.kuleuven.be
The aim of this study was to investigate the role of diet-induced thermogenesis (DIT) in the regulation of feed intake in age-matched broiler and layer cockerels. In addition, the effect of genotype on endocrine functioning and key metabolites of the intermediary metabolism as well as on the expression of muscular uncoupling protein (avUCP) was explored. One-day-old male broiler (Ross) and layer (ISA Brown) chicks were reared under standard conditions on commercial broiler starter and finisher diets. From 22 d of age, twice per week, 3 broiler and 6 layer cockerels were placed in open circuit respiratory chambers. After adaptation, the animals were feed-deprived for 24 h, and heat production was measured by indirect calorimetry. During the subsequent 7-h refeeding period, feed intake and DIT were measured. Blood samples were taken after feed deprivation and re-feeding. Muscle samples were taken after refeeding for determination of avUCP expression. A significantly higher heat production per metabolic BW (MBW) in the layer compared with the broiler cockerels, independent of nutritional state, suggests that the broilers used a greater proportion of the metabolizable energy intake for growth. The DIT per MBW and per gram of feed intake was higher for the layer than for the broiler cockerels. However, feed intake per MBW was also significantly higher in the layer cockerels. Thus, no feedback effect of DIT on feed intake per MBW was observed, and the model formulated for adult mammals relating feed intake to DIT could not be corroborated. The muscular expression of avUCP was not different between genotypes, which does not support the hypothesis of an involvement of avUCP in the higher DIT measured in layer cockerels. Circulating uric acid, glucose, triglyceride, and free fatty acid levels were significantly elevated in the layer compared with the broiler cockerels. As the diet was formulated according to broiler requirements, the higher metabolite levels of the layer cockerels might reflect a relative oversupply of dietary nutrients.
Key Words: genotype diet-induced thermogenesis feed intake regulation broiler chicken layer chicken
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Q. Swennen, P.-J. Verhulst, A. Collin, A. Bordas, K. Verbeke, G. Vansant, E. Decuypere, and J. Buyse Further Investigations on the Role of Diet-Induced Thermogenesis in the Regulation of Feed Intake in Chickens: Comparison of Adult Cockerels of Lines Selected for High or Low Residual Feed Intake Poult. Sci., September 1, 2007; 86(9): 1960 - 1971. [Abstract] [Full Text] [PDF] |
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