Níveis de energia metabolizável e relações energia:proteína para aves de corte de crescimento lento criadas em sistema semiconfinado

Abstract

RESUMO. Foram conduzidos três ensaios para determinar as exigências de energia metabolizável (EM) e a melhor relação energia:proteína (E:P) para fêmeas de corte de crescimento lento, criadas em sistema semiconfinado nas fases inicial, crescimento e final. O delineamento experimental foi o inteiramente casualizado com cinco níveis de EM (tratamentos) e quatro repetições de 20 aves cada. Os níveis de EM na fase inicial variaram de 2600 a 3200 kcal kg-1 , crescimento de 2700 a 3300 kcal kg-1 , e na fase final de 2800 a 3400 kcal kg-1. A proteína bruta e os demais nutrientes foram mantidos constantes em todas as rações. A relação E:P e o nível de EM que maximizaram o desempenho e as características da carcaça das fêmeas ISA Label em cada fase estudada foram: 128 e 2750 (inicial); 147 e 2850 (crescimento); 172 e 3100 kcal de EM kg-1 na ração (final).

Metabolizable energy for broilers with different genetic growth potentials under a free-range system

“…It is known that dietary metabolizable energy level plays a key role in broiler feed intake regulation and feed efficiency (Abudabos et al,2014) . Mendonça et al (2007), working with females of the slow-growing broiler lineage "Isa Label" from 22 to 49 days and from 50 to 84 days did not observe an effect of the energy level on weight gain during either evaluation period. However, in Mendonça et al (2008), a quadratic effect of the metabolizable energy level (2800 to 3400 kcal/kg) on the weight gain of slow-growing male broilers between 50 and 70 days old reared in a free-range system was observed, with an estimated 3222 kcal/ kg energy level expected to provide greater weight gain.…”

“…Previous research has also shown similar behavior. Mendonça et al (2007), working with females of the lineage "Isa Label", observed a linear decrease in the intake during three study stages. The same effect was reported by Mendonça et al (2008) when working with males of the same lineage.…”

“…There was a quadratic effect of the feed energy level on feed conversion, and the feed energy level was estimated at 3046 kcal/ kg for the best response in food conversion. Mendonça et al (2007) tested 5 feed energy levels ranging from 2800 to 3400 kcal/kg during the initial phase (1 to 21 days old), the growth phase (22 to 49 days old) and the final phase (50 to 85 days old) and found a linear effect of the feed energy level on the feed conversion in all evaluation periods. Similarly, Ferreira et al (2015), working with free-range broilers, observed a linear effect on the improvement of feed conversion with an increase in the feed energy level.…”