The effect of inclusion of oat hulls in piglet diets based on raw or cooked rice and maize

An experiment was conducted to investigate the influence of the main cereal (maize and rice), heat-processing of the cereal (HP; raw and cooked) and the inclusion of cooked oat hulls (OH; 0 and 20 g/kg) in the diet on coefficient of total tract apparent digestibility of major dietary components (CTTAD) and productive performance of piglets weaned at 21 days. Each treatment was replicated six times and the trial lasted for 35 days. From 21 to 49 days of age piglets were fed their respective experimental complex diets and from 49 to 56 days they received a common starter diet. The CTTAD was determined at 33, 43 and 49 days and productive performance was measured at 35, 49 and 56 days of age. Gross energy (GE), organic matter (OM) and ether extract (EE) digestibilities were higher for rice- than for maize-based diets (P<0.001 for GE and OM and P<0.05 for EE) but digestibility of crude protein was not affected by the cereal used. Heat processing improved CTTAD of all dietary components examined (P<0.01). The CTTAD of OM was lower for diets containing 20 g OH/kg than for control diets (P<0.01) but the opposite effect was observed for EE digestibility (P<0.05). From 21 to 49 days of age piglets fed rice had higher feed intake (580 versus 491; P<0.001) and average daily gain (388 versus 332; P<0.001) than piglets fed maize. The differences observed were maintained until the end of the trial. Neither HP of the cereal nor OH inclusion affected any productive trait. It is concluded that the inclusion of rice in substitution of maize in pre-starter feeds for piglets improves diet digestibility and growth performance; HP of the cereal improves diet digestibility but not growth performance and the inclusion of moderate levels of OH to low fibre diets has minor effects on diet digestibility and productive performance of young pigs.