Effect of method of delivery of sodium butyrate on maturation of the small intestine in newborn calves

The effect of sodium butyrate (SB) supplementation in milk replacer (MR), starter mixture (SM), or both on small intestine maturation in newborn calves was investigated. Twenty-eight male calves with a mean age of 5 (±1) d were randomly allocated into 1 of 4 groups (7 animals per group) and fed (1) MR and SM, without SB (MR⁻ and SM⁻, respectively; MR⁻/SM⁻); (2) MR⁻ and SM supplemented with SB encapsulated within triglyceride matrix (SM⁺, 0.6% as fed; MR⁻/SM⁺); (3) MR supplemented with crystalline SB (MR⁺, 0.3% as fed) and SM⁻ (MR⁺/SM⁻); or (4) MR⁺ and SM⁺ (MR⁺/SM⁺). The MR was offered in amounts equal to 10% of initial body weight of the calf. The SM was blended with whole corn grain (50/50; wt/wt) and offered ad libitum as a starter diet. Calves were slaughtered at 26d (±1) of age and small intestine development was investigated. Treatment with MR⁺ decreased villus height in the proximal jejunum and decreased villus height, crypt depth, and tunica mucosa thickness in the middle jejunum, whereas treatment with SM⁺ tended to increase small intestine weight and crypt depth in the proximal jejunum, and increased villus height in the distal jejunum. In the duodenum, crypt depth and tunica mucosa thickness were greater for the MR⁻/SM⁺ group compared with MR⁻/SM⁻, MR⁺/SM⁻, and MR⁺/SM⁺ groups. In the ileum, crypt depth was less for MR⁻/SM⁺ compared with MR⁻/SM⁻. Supplementation with SB in both MR and SM enhanced cell proliferation and decreased apoptosis in the middle jejunum mucosa. Regarding brush border enzyme activities, addition of SB to MR increased lactase activity in the middle jejunum and maltase activity in the distal jejunum, and tended to increase lactase activity in the distal jejunum, aminopeptidase A activity in the middle jejunum and ileum, and aminopeptidase N activity in the ileum. In contrast, SM⁺ increased dipeptidylpeptidase IV activity in the distal jejunum and tended to increase aminopeptidase N in the distal jejunum. In conclusion, both MR⁺ and SM⁺ affected small intestine development in newborn calves. This effect depended on the method of SB delivery but MR⁺ generally had a more pronounced effect. No synergistic effect of SB supplementation into MR and SM was found.