• Asian-Australasian Journal of Animal Sciences
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• v.30 no.6
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• pp.849-856
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• 2017

Objective: The net energy requirement for the maintenance ($NE_m$) of broilers was determined using regression models by the indirect calorimetry method (ICM) or the comparative slaughter method (CSM). Methods: A $2{\times}4$ factorial arrangement of treatments including the evaluation method (ICM or CSM) and feed intake (25%, 50%, 75%, or 100% of ad libitum recommended) was employed in this experiment. In the ICM, 96 male Arbor Acres (AA) birds aged d 15 were used with 4 birds per replicate and 6 replicates in each treatment. In the CSM, 116 male AA birds aged d 15 were used. Among these 116 birds, 20 were selected as for initial data and 96 were assigned to 4 treatments with 6 replicate cages and 4 birds each. The linear regression between retained energy (RE) and metabolizable energy intake (MEI) or the logarithmic regression between heat production (HP) and MEI were used to calculate the metabolizable or net energy requirement for maintenance ($ME_m$) or $NE_m$, respectively. Results: The evaluation method did not detect any differences in the metabolizable energy (ME), net energy (NE), and NE:ME of diet, and in the MEI, HP, and RE of broilers. The MEI, HP, and RE of broilers decreased (p<0.01) as the feed intake decreased. No evaluation method${\times}$feed intake interaction was observed on these parameters. The $ME_m$ and $NE_m$ estimated from the linear relationship were 594 and 386 kJ/kg of body weight $(BW)^{0.75}/d$ in the ICM, and 618 and 404 kJ/kg of $BW^{0.75}/d$ in the CSM, respectively. The $ME_m$ and $NE_m$ estimated by logarithmic regression were 607 and 448 kJ/kg of $BW^{0.75}/d$ in the ICM, and were 619 and 462 kJ/kg of $BW^{0.75}/d$ in the CSM, respectively. Conclusion: The NEm values obtained in this study provide references for estimating the NE values of broiler diets.

• Animal Bioscience
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• v.35 no.5
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• pp.690-697
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• 2022

Objective: This study aimed to evaluate the effect of the ad libitum and restricted feeding regimen on fasting heat production (FHP) and body composition. Methods: Twelve Hubbard broilers breeders were selected with the same body weight and submitted in two feeding regimes: Restricted (T1) with feed intake of 150 g/bird/d and ad libitum (T2). The birds were randomly distributed on the treatments in two runs with three replications per treatment (per run). The birds were adapted to the feed regimens for ten days. After that, they were allocated in the open-circuit chambers and kept for three days for adaptation. On the last day, oxygen consumption (VO₂) and carbon dioxide production (VCO₂) were measured by 30 h under fasting. The respiratory quotient (RQ) was calculated as the VCO₂/VO₂ ratio, and the heat production (HP) was obtained using the Brower equation (1985). The FHP was estimated throughout the plateau of HP 12 hours after the feed deprivation. The body composition was analyzed by dual-energy X-ray absorptiometry scanning at the end of each period. Data were analyzed for one-way analysis of variance using the Minitab software. Results: The daily feed intake was 30 g higher to T2 (p<0.01) than the T1. Also, the birds of the T2 had significatively (p<0.05) more oxygen consumption (+3.1 L/kg^0.75/d) and CO₂ production (+2.2 L/kg^0.75/d). That resulted in a higher FHP 359±14 kJ/kg^0.75/d for T2 than T1 296±17.23 kJ/kg^0.75/d. In contrast, the RQ was not different between treatments, with an average of 0.77 for the fasting condition. In addition, protein and fat composition were not affected by the treatment, while a tendency (p<0.1) was shown to higher bone mineral content on the T1. Conclusion: The birds under ad libitum feeding had a higher maintenance energy requirement but their body composition was not affected compared to restricted feeding.