Abstract
Two trials were carried out to study the energy restriction (3200, 2960 and 2720 kcal of ME kg-1 ) for late finishing pigs, by means of adding dietary fiber (ground rice hull). Experiment I - 36 pigs were used (69.39 ｱ 5.38 kg). The variables studied (performance, carcass traits and PUN) were separated according to the slaughter weight (70-90 kg and 90-115 kg). 12 pigs weighting 87.55 ｱ 3.12 kg and 15 pigs weighting 115.41 ｱ 6.20 kg were slaughtered. None of the variables studied were influenced by the different levels of ME. Experiment II -15 barrows were used (84.8 ｱ 4.5 kg) and kept on metabolism crates. There was a linear increase of total feces, dry matter (DM) and organic matter output, according to dietary energy reduction, without causing an increase in total phosphorous (P) and nitrogen (N) excretion. Digestibility coefficient of DM and crude protein decreased, which led to a decrease in daily weight gain and an increase in feed: gain ratio. Results suggest the possibility to slaughter high lean meat pigs, weighting up to 115 kg, without impairing performance and carcass traits, regardless dietary energy level. However, total feces output increased without causing an increase in N and P excretion, as ME decreased and crude fiber increased.
Highlights
There was a linear increase of total feces, dry matter (DM) and organic matter output, according to dietary energy reduction, without causing an increase in total phosphorous (P) and nitrogen (N) excretion
Digestibility coefficient of DM and crude protein decreased, which led to a decrease in daily weight gain and an increase in feed: gain ratio
Total feces output increased without causing an increase in N and P excretion, as metabolizable energy (ME) decreased and crude fiber increased
Summary
Sendo um experimento de desempenho e outro de digestibilidade. As rações experimentais (Tabela 1) foram as mesmas para os dois experimentos. A ração do T1 continha 0,68 e 0,56% de lisina, respectivamente, para as fases 70-90 kg e 90-115 kg, sendo os níveis dos demais nutrientes ajustados de acordo com o recomendado pelo NRC (1998). Para os T2 e T3, foi adicionada a casca de arroz moída (como fonte de fibra) à ração para reduzir os níveis de EM em 7,5 e 15%, respectivamente (Tabela 1). No período pré-experimental (55 kg aos 69,39 ± 5,38 kg de PV), os animais receberam a mesma ração, contendo níveis nutricionais indicados pelo NRC (1998), conforme Tabela 1. No período experimental de 69,39 ± 5,38 kg até os 114,04 ± 9,09 kg, as dietas foram divididas em duas fases (70 a 90 kg e 90 a 115 kg), como apresentado na Tabela 1
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