EFFECT OF EXPANDER CONDITIONING AND OR PELLETING OF A DIET ON THE ILEAL DIGESTIBILITY OF NUTRIENTS AND ON FEED-INTAKE AFTER CHOICE FEEDING OF PIGS/

A pig diet, processed in three different ways, was evaluated in an ile al digestibility trial. The complete diet contained mainly pea, tapioc a and soybean meal and was processed by steam-pelleting (SP), high-she ar conditioning (expander treatment; E) and expander-pelleting (EP), r espectively. Expander-pelleting clearly improved the physical quality of pellets in terms of hardness and durability as compared to steam-pe lleting. The apparent ileal digestibility of dietary nitrogen, dry mat ter, organic matter and crude fat determined with piglets in the weigh t range of 20-25 kg was not affected by the technological treatments u nder investigation. Only the crude fibre digestibility was significant ly improved by single expander conditioning (P < 0.05); the absolute l evel of 7.6% however was of low significance. Under the conditions of the present study, high shear conditioning (expander treatment) prior to pelleting showed no favourable effects on the apparent ileal digest ibility of nutrients. Feed intake of the diets, offered in a choice fe eding design to piglets of about 27 kg liveweight showed a large varia tion between piglets but in favour of the SP and E diet. Since diet ha rdness is related directly to the animal feed intake, maximisation of diet durability of expanded or pelleted diets should be achieved in re lation to an optimisation of diet hardness and nutrient utilisation in piglets. (C) 1998 SCI.