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Body constituents retention for broilers at 7 days old according to temperature

Rodrigo Borille ; Carla Heloisa de Faria Domingues ; Gustavo D. Lovato ; Patricia C. Aristimunha ; Giovani Farina ; Carlos Ongaratto ;  Bruna Schroeder ; Alexandre de Mello Kessler
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Considering that part of intake metabolizable energy (ME) is retained in the body and part is lost as heat (heat increment), the proportion retained represents the efficiency of ME conversion of diet in liquid energy. The aim of the study was to evaluate body constituents retention for broilers at 7 days old raised in different temperatures. Were used 300 broilers from 1 day old lineage "Cobb 500", distributed in 30 boxes. Each box was submitted to different temperatures for 7 days (the variation of environmental temperature among all the boxes were 21?C to 34.5 ?C). Experimental diets were formulated according to Rostagno et al. (2011). Apparent metabolizable energy content of diet was 3180.20 kcal/kg feed, estimated by recovery of chromium oxide in excreta added to the feed in proportion of 0.14%. Metabolizable energy intake (MEI kcal/bird/day) was measured based on feed intake of the period. From comparative culling technique, protein contents (g/bird/day), fat (g/bird/day) and crude energy (kcal/bird/day) retained in the body were analyzed by the difference between the beginning and ending of experiment. Statistical analyzes were performed using regression analyzes (P<0,01; linear and/or quadratic). Temperature was considered independent variable. MEI, protein, fat and energy retained were considered dependent variables. There was quadratic effect (P<0.01) between temperature levels for MEI (MEI=-68.72+9.569*T-0.1743*T?), with an estimating of maximum MEI of 62.6kcal/bird/day at 27.6 ?C. Protein (P=-7.683+0.7022*T-0.01230*T?), fat (F=-4.049+0.3532*T-0.005984*T?) and crude energy (CE=-88.47+7.850*T-0.1358*T?) also showed quadratic effect (P<0.01). Estimating of maximum retention of protein (2.33 g/bird/day) occurred at 28.5 ?C, for fat (1.16 g/bird/day) at 29.5 ?C and for crude energy (24.9 kcal/bird/day) at 28.9 ?C. According to the present study, temperature can change body constitution of broilers from 1 to 7 days old. The highest body constitution retention occurred between 28.5 ?C and 29.5 ?C.