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ORIGINAL PAPER
Assessment of metabolizable energy requirements for broilers
in both conventional indoor and free-range rearing systems
1
Alexandria University, Faculty of Agriculture (El-Shatby), Poultry Production Department,
21545 Alexandria, Egypt
2
Universidad Autónoma de Yucatán (UADY), Facultad de Medicina Veterinaria y Zootecnia (CCBA),
97315 Mérida, Yucatán, Mexico
3
Cairo University, Faculty of Agriculture, Department of Animal Production, 12613 Cairo, Egypt
Publication date: 2026-03-27
Corresponding author
L. A. Sarmiento-Franco
Universidad Autónoma de Yucatán (UADY), Facultad de Medicina Veterinaria y Zootecnia (CCBA), 97315 Mérida, Yucatán, Mexico
Universidad Autónoma de Yucatán (UADY), Facultad de Medicina Veterinaria y Zootecnia (CCBA), 97315 Mérida, Yucatán, Mexico
KEYWORDS
TOPICS
ABSTRACT
The current study aimed to determine the metabolizable energy
(ME) requirements of broiler chickens reared under free-range conditions and
compared their energy use and performance with birds raised in a conventional
indoor system. Ninety-six Cobb-500 male broilers were assigned to indoor or
free-range treatments from 14 to 42 days of age. Growth performance, behaviour,
and energy partitioning were assessed. A digestibility trial and comparative
slaughter method were used to determine ME intake (MEI), energy retention,
and heat production (HP). No significant differences were observed in body
weight (BW) gain, feed intake, or feed conversion ratio between both systems.
Free-range broilers displayed significantly higher foraging and locomotion, and
reduced feeding and resting behaviours, reflecting their increased physical
activity. Consequently, they retained less energy (mainly in the form of body fat)
and had higher HP than indoor birds. The additional ME required for outdoor
activity in the free-range group was estimated at 40.50 kcal/kg BW0.75/day,
representing approximately 8% of total MEI. Free-range broilers maintained
productive performance despite higher energy demand and expressed more
natural behaviours. These results indicate that dietary energy supply in freerange
systems may require adjustment to improve feeding strategies in order to
balance economic efficiency and animal welfare.
CONFLICT OF INTEREST
The Authors declare that there is no conflict of interest.
REFERENCES (29)
1.
Abouelezz K.F.M., Wang Y., Wang W., Lin X., Li L., Gou Z., Fan Q., Jiang S., 2019. Impacts of graded levels of metabolizable energy on growth performance and carcass characteristics of slow-growing yellow-feathered male chickens. Animals (Basel). 9, 461, https://doi.org/10.3390/ani907....
2.
Ahiwe E.U., Omede A.A., Abdallh M.B., Iji P.A., 2018. Managing dietary energy intake by broiler chickens to reduce production costs and improve product quality. In: B. Yücel, T. Taşkin (Editors). Animal Husbandry and Nutrition. IntechOpen Ltd. London (UK), pp. 115–145, https://doi.org/10.5772/intech....
3.
AOAC International, 2000. Official Methods of Analysis 17th Edition. Association of Official Analytical Chemists. Washington, DC (USA).
4.
Bartlett J.R., Liles K.M., Beckford R.C., 2015. Comparing the effects of conventional and pastured poultry production systems on broiler performance and meat quality. J. Agric. Life Sci. 2, 29–36.
5.
Bokkers E.A.M., Koene P., 2003. Behaviour of fast- and slow-growing broilers to 12 weeks of age and the physical consequences. Appl. Anim. Behav. Sci. 81, 59–72, https://doi.org/10.1016/S0168-....
6.
Brainer M.M.A., Rabello C.B.V., Santos M.J.B., Lopes C.C., Ludke J.V., Silva J.H.V., Lima R.A., 2016. Prediction of the metabolizable energy requirements of free-range laying hens. J. Anim. Sci. 94, 117–124, https://doi.org/10.2527/jas.20....
7.
Campbell Y.L., Walker L.L., Bartz B.M., Eckberg J.O., Pullin A.N., 2025. Outdoor access versus conventional broiler chicken production: Updated review of animal welfare, food safety, and meat quality. Poult. Sci. 104, 104906, https://doi.org/10.1016/j.psj.....
8.
Chwalibog A., 1991. Energetics of animal production. Acta Agric. Scand. 41, 147–160, https://doi.org/10.1080/000151....
9.
CONAGUA, 2020. Tables of average temperatures at the national level and by state from January to December 2020 (in Spanish). Reporte del Clima en México. Comision Nacional del Agua (Mexico).
10.
Duncan D.B., 1955. Multiple range and multiple “F” test. Biometrics 11, 1–42, https://doi.org/10.2307/300147....
11.
Fanatico A.C., Mench J.A., Archer G.S., Liang Y., Brewer Gunsaulis V.B., Owens C.M., Donoghue A.M., 2016. Effect of outdoor structural enrichments on the performance, use of range area, and behavior of organic meat chickens. Poult. Sci. 95, 1980–1988, https://doi.org/10.3382/ps/pew....
12.
Fanatico A.C., Pillai P.B., Hester P.Y., Falcone C., Mench J.A., Owens C.M., Emmert J.L., 2008. Performance, livability, and carcass yield of slow- and fast-growing chicken genotypes fed low-nutrient or standard diets and raised indoors or with outdoor access. Poult. Sci. 87, 1012–1021, https://doi.org/10.3382/ps.200....
13.
Liu W., Lin C.H., Wu Z.K., Liu G.H., Yan H.J., Yang H.M., Cai H.Y., 2017. Estimation of the net energy requirement for maintenance in broilers. Asian-Australas. J. Anim. Sci. 30, 849–856, https://doi.org/10.5713/ajas.1....
14.
Lopez G., Leeson S., 2008. Assessment of the nitrogen correction factor in evaluating metabolizable energy of corn and soybean meal in diets for broilers. Poult. Sci. 87, 298–306, https://doi.org/10.3382/ps.200....
15.
Lusk J.L., 2018. Consumer preferences for and beliefs about slow growth chicken. Poult. Sci. 97, 4159–4166, https://doi.org/10.3382/ps/pey....
16.
Noblet J., van Milgen J., Carre B., Dimon P., Dubois S., Rademacher M., van Cauwenberghe S., 2003. Effect of body weight and dietary crude protein on energy utilization in growing pigs and broilers. In: W.B. Souffrant, C.C. Metges (Editors). Progress in Research on Energy and Protein Metabolism. Wageningen Academic Publishers. Wageningen (Netherlands), pp. 205–208, https://doi.org/10.3920/978908....
17.
Połtowicz K., Doktor J., 2011. Effect of free-range raising on performance, carcass attributes and meat quality of broiler chickens. Anim. Sci. Pap. Rep. 29, 139–149.
18.
Ponte P.I.P., Rosado C.M.C., Crepso J.P. et al., 2008. Pasture intake improves the performance and meat sensory attributes of free-range broilers. Poult. Sci. 87, 71–79, https://doi.org/10.3382/ps.200....
19.
Ravindran V., Hew L., Ravindran G., Bryden W., 1999. A comparison of ileal digesta and excreta analysis for the determination of amino acids digestibility in food ingredients for poultry. Br. Poult. Sci. 40, 266–274, https://doi.org/10.1080/000716....
20.
Sakomura N.K., Fernandes J.B.K., Resende K.T., Rabello C.B.V., Longo F., Neme R., 2011. Modelling energy utilization in poultry. In: D. Sauvant, J. Milgen, P. Faverdin, N. Friggens (Editors). Modelling Nutrient Digestion and Utilisation in Farm Animals. Wageningen Academic Publishers. Wageningen (Netherlands), pp. 297–305, https://doi.org/10.3920/978-90....
21.
Sakomura N.K., Silva R., Couto H.P., Coon C., Pacheco C.R., 2003. Modelling metabolizable energy utilization in broiler breeder pullets. Poult. Sci. 82, 419–427, https://doi.org/10.1093/ps/82.....
22.
Sánchez-Casanova R., Sarmiento-Franco L., Segura-Correa J., Phillips C.J.C., 2019. Effects of outdoor access and indoor stocking density on behaviour and stress in broilers in the subhumid tropics. Animals 9, 1016, https://doi.org/10.3390/ani912....
23.
Sánchez-Casanova R.E., Sarmiento-Franco L., Phillips C.J.C., 2022. The effects of providing outdoor access to broilers in the tropics on their behaviour and stress responses. Animals 12, 1917, https://doi.org/10.3390/ani121....
24.
Scott M.L., Nesheim M.C., Young R.J., 1982. Nutrition of the Chicken. Nottingham University Press. Ithaca, NY (USA), pp. 312–357.
25.
Silva R.T., Nascimento R.S.K.M., Kiefer C., Copat L.L.P., Freitas B.H., Chaves N.R.B., Silva R.L.A., Leite J.V., Ofiço A.V., 2021. Metabolizable energy levels in diets with a fixed nutrient: calorie ratio for free-range broilers. Semin. Ciênc. Agrár. 42, 4009–4022, https://doi.org/10.5433/1679-0....
26.
Skomorucha I., Muchacka R., Sosnówka-Czajka E., Herbut E., 2008. Effects of rearing with or without outdoor access and stocking density on broiler chicken productivity. Ann. Anim. Sci. 8, 387–393.
27.
Tong H.B., Cai J., Lu J., Wang Q., Shao D., Zou J.M., 2015. Effects of outdoor access days on growth performance, carcass yield, meat quality, and lymphoid organ index of a local chicken breed. Poult. Sci. 94, 1115–1121, https://doi.org/10.3382/ps/pev....
28.
van Milgen J., Noblet J., Dubois S., 2001. Energetic efficiency of starch, protein, and lipid utilization in growing pigs. J. Nutr. 131, 1309–1318, https://doi.org/10.1093/jn/131....
29.
Wang K.H., Shi S.R., Dou T.C., Sun H.J., 2009. Effect of a free-range raising system on growth performance, carcass yield, and meat quality of slow-growing chicken. Poult. Sci. 88, 2219–2223, https://doi.org/10.3382/ps.200....
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