title: Fasting heat production and metabolic BW in group-housed broilers.
abstract: Fasting heat production (FHP) is used for characterizing the basal metabolic rate of animals and the corresponding maintenance energy requirements and in the calculation of net energy value of feeds. In broilers, the most recent FHP estimates were obtained in the 1980s in slow-growing and fatter birds than nowadays. The FHP values (n=73; six experiments) measured in 3 to 6-week-old modern lines of broilers weighing 0.6 to 2.8 kg and growing at 80 to 100 g/day were used to update these literature values. Each measurement was obtained in a group of fasting broilers (5 to 14 birds) kept in a respiration chamber for at least 24 h. The FHP estimate corresponds to the asymptotic heat production corrected for zero physical activity obtained by modeling the decrease in heat production during the fasting day. The compilation of these data indicates that FHP was linearly related to the BW(0.70) (in kg), which can be considered as the metabolic BW of modern broilers. The 0.70 exponent differs from the conventional value of 0.75 used for mature animals. The FHP per kg of BW(0.70) ranged between 410 and 460 kJ/day according to the experiment (P<0.01). An experiment conducted with a shorter duration of fasting (16 h) indicated that FHP values are higher than those obtained over at least 24 h of fasting. Our values are similar to those obtained previously on fatter and slow-growing birds, even though the comparison is difficult since measurement conditions and methodologies have changed during the last 30 years. The FHP values obtained in our trials represent a basis for energy nutrition of modern broilers.
authors.affiliation: 1INRA,UMR1348 Pegase,F-35590 Saint Gilles,France.
authors.forename: J
authors.initials: J
authors.lastname: Noblet
authors.affiliation: 1INRA,UMR1348 Pegase,F-35590 Saint Gilles,France.
authors.forename: S
authors.initials: S
authors.lastname: Dubois
authors.affiliation: 1INRA,UMR1348 Pegase,F-35590 Saint Gilles,France.
authors.forename: J
authors.initials: J
authors.lastname: Lasnier
authors.affiliation: 3Federal University of Parana,88035 Curitiba,Parana,Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Warpechowski
authors.affiliation: 1INRA,UMR1348 Pegase,F-35590 Saint Gilles,France.
authors.forename: P
authors.initials: P
authors.lastname: Dimon
authors.affiliation: 4INRA,UR83 Recherches Avicoles,F-37380 Nouzilly,France.
authors.forename: B
authors.initials: B
authors.lastname: Carré
authors.affiliation: 1INRA,UMR1348 Pegase,F-35590 Saint Gilles,France.
authors.forename: J
authors.initials: J
authors.lastname: van Milgen
authors.affiliation: 1INRA,UMR1348 Pegase,F-35590 Saint Gilles,France.
authors.forename: E
authors.initials: E
authors.lastname: Labussière
mesh_terms: D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D005215:Fasting / Q000502:physiology*; D008954:Models, Biological; D022722:Thermogenesis / Q000502:physiology*; D013997:Time Factors
keywords: broiler; calorimetry; energy; fasting heat production; metabolic BW