Effects of maternal supplementation and inclusion of protected fat in the finishing diet on nutrient digestibility and expression of intestinal genes in Nellore steers

Abstract

Maternal nutrition during pregnancy has potential impact on nutrient utilization by the offspring. The study had the objective to evaluate total nutrient digestibility of Nellore progeny from cows supplemented during mid to late gestation, fed diets with o r without rumen-protected fat. In addition, it was analyzed the gene expression of transporters in the small intestine, as well as α-amylase activity. Forty-eight Nellore steers, averaging 21 ± 0.7 mo and 340 ± 9.38 kg, were housed in individual pens and allotted in a completely randomized design using a 2 x 2 factorial arrangement, totaling 12 replicates per treatment. The treatments were: not supplemented dams (NS) or supplemented dams (SUPP) during mid to late gestation; and diets without rumen-protected fat (NFAT) or with rumen-protected fat (RPF - 6% calcium salts) during feedlot phase. Cows’ supplementation (369 g crude protein and 2.11 Mcal/d) started after 124 ± 21 d of gestation. Total nutrient digestibility was evaluated by total feces collection. α-amylase activity was analyzed in pancreas tissue using a commercial kit. Duodenal and jejunal samples were taken to analyze the expression of SLC5A1, CD36 and CCK mRNA genes and villi morphometry. Progeny from not supplemented cows and fed RPF had the lowest dry matter intake. Feeding RPF decreased (P < 0.01) the intake of non-fiber carbohydrates, crude protein and starch, whilst increased the digestibility (P < 0.01) of dry matter, organic matter, neutral detergent fiber, crude protein, ether extract, starch and total digestible nutrients. Inclusion of RPF decreased starch content in feces (P < 0.01) and fecal output (P < 0.01), whereas increased fecal pH (P < 0.01). Maternal supplementation tended to decrease (P = 0.07) villus height of duodenum, whereas the inclusion of RPF tended to decreased crypt depth (P = 0.07) of jejunum of the progeny. Activity of α-amylase was unaffected by maternal supplementation (P > 0.28) or RPF inclusion (P > 0.87). Duodenal expression of SLC5A1, CD36 and CCK mRNA increased in progeny from not supplemented cows. Supplementation of beef cows during mid to late gestation does not alter the apparent digestibility of nutrients in the offspring during the finishing phase. However, it decreases the expression of SLC5A1, CD36 and CCK mRNA in duodenum. Steers fed rumen-protected fat have lower intake in the feedlot, but they have better nutrient digestibility.