INFLUENCE OF HIGH-FIBER DIETS GIVEN TO GESTATING SOWS ON SERUM CONCENTRATIONS OF MICRONUTRIENTS

The objective of the present woek was to evaluate the effects of high fibre diets given to sows during two consecutive gestations on the evo lution of serum concentrations of some micronutrients. Eighty-eight gi lts were distributed among the three following experimental diets: (1) corn-soybean meal, (2) corn cobs-wheat bran and (3) oats-oat hulls. D ietary fibre represented 14, 30 and 46% of diets 1, 2 and 3, respectiv ely. Blood samples were taken from the jugular vein at 5, 10 and 15 wk of gestation from all sows at each parity. In the first parity, serum concentration of folates per unit of folates ingested was higher with diet 1 (P = 0.003), whereas it was the opposite in the second gestati on, serum folates being higher with diets 2 and 3 (P = 0.02). In the f irst gestation, the lowest serum concentration of vitamin B-12 per uni t ingested was observed in sows fed diet 2 (P less than or equal to 0. 05); in the second gestation, serum vitamin B-12 was lower for sows fe d diets 2 and 3 than for those fed diet 1 (P less than or equal to 0.0 5). Serum concentrations of calcium, phosphorus, copper and zinc per u nit of mineral ingested were lower in sows fed the two high fibre diet s (P less than or equal to 0.05). Serum concentrations of these minera ls were lower in second than in first parity whatever the diet (P less than or equal to 0.05). Results of the present study give an indicati on that feeding high fibre diets to gestating sows could reduce B-comp lex vitamin, especially vitamin B-12, availability. Responses of serum concentrations of minerals to dietary treatments, in spite of the lim itations of these measurements, also raise the question of the effect of dietary fibre on mineral availability. Supplementary studies, mainl y on mineral metabolism, need to be conducted to confirm these observa tions and to define precisely the composition of premixes in order to maintain the B-complex vitamin and mineral status of gestating sows fe d high fibre diets at an optimum level.