Effects of tributyrin supplementation in calf starter on growth, blood parameters and development of rumen and small intestine in Holstein calves fed milk replacers with different fatty acid profile

Abstract

The objective of this study was to evaluate the effects of tributyrin (TB) supplementation in calf starter on development of the rumen and small intestine for calves fed two milk replacers differing in fatty acid composition. Fifty-four Holstein calves (38 heifers and 16 bull calves) were assigned to one of the four treatments: (1) milk replacer containing 31 g/kg C8:0 and 29 g/kg C10:0 in total fatty acids (MR-) and calf starter without TB (ST-) (MR-ST-; n = 14), (2) MR- and calf starter with a TB supplement (600 g/kg TB and 400 g/kg silicon dioxide) at 6 g/kg of DM (ST+) (MR-ST+; n = 13), (3) milk replacer containing 26 g/kg C4:0, 57 g/kg C8:0, and 56 g/kg C10:0 in total fatty acids (MR+) and ST- (MR+ST-; n = 13), and (4) MR+ and ST+ (MR+ST+; n = 14). Milk replacers were offered at 600 g/d (powder basis) from 8 to 14 d, increased up to 1300 g/d from 15 to 21 d, 1400 g/d from 22 to 49 d, decreased down to 700 g/d from 50 to 56 d, and 600 g/d from 57 to 63 d, and then weaned at 64 d of age. Data and samples were collected until 91 d of age. All the calves were fed one of the calf starters and chopped hay ad libitum from 8 d of age. Bull calves were euthanized at weaning to determine weights of digestive organs and evaluate ruminal and small intestinal morphology. Calf starter and milk replacer treatments did not affect dry matter intake, growth performance, digestive organs weights (kg/100 kg of body weight), and rumen papillae length. However, calves fed ST+ had greater ratio of villus height to crypt depth (2.20 vs. 1.84; P < 0.01) in the ileum compared to those fed ST-. In addition, calves fed MR+ had less crypt depth (240 vs. 298 µm; P = 0.02) and greater ratio of villus height to crypt depth (2.22 vs. 1.91; P < 0.01) in the ileum compared to those fed MR-. A tendency for interaction between milk replacer and calf starter treatments was observed for the ratio of villus height to crypt depth in the jejunum, in which TB in calf starter increased the ratio only for calves fed MR-. Milk replacer treatment did not affect plasma glucagon-like peptide-2 (GLP-2) concentration. However, calves fed ST+ had greater plasma GLP-2 concentration compared to those fed ST- after weaning (1.16 vs. 0.80 ng/mL; P < 0.02). These results suggest that TB supplementation for dairy calves may affect small intestinal morphology at weaning, and increase plasma GLP-2 concentration after weaning.