Lanolin-derived branched-chain fatty acids supplementation in early-life Holstein calves.

This study was conducted to explore the effects of branched-chain fatty acids derived from lanolin (BCFA-DFL) on growth performance, digestibility, blood metabolites, intestinal development, and fecal bacterial structure of calves aged 0 to approximately 28 d. Twenty-four newborn Holstein dairy calves (birth weight = 41.88 ± 4.56 kg, mean ± SD) were divided into the control group receiving whole milk without BCFA-DFL and the treatment group (BCFA) receiving whole milk with BCFA-DFL (4 g/d) supplementation according to the randomized block design based on their birth weight and birth date. Calves fed BCFA-DFL had higher ADG, feed efficiency, heart girth, and total-tract apparent digestibility of nutrients, but the treatments did not affect total DMI. Plasma cholesterol and haptoglobin were lower in calves fed BCFA-DFL than in the control group. The BCFA-DFL supplementation reduced the frequency of diarrhea, the duration of diarrhea, and the number of medication doses required for treating diarrhea. In contrast to the control group, feeding BCFA-DFL increased the gene relative expression of tight junction protein 1, claudin 2, β-defensin-1, β-defensin 4, regenerating islet-derived protein (REG) 3α, REG 3γ, and IL-10 in the small intestine of calves, while decreasing the gene relative expression of IL-1β and TNF-α. Supplementation with BCFA significantly elevated the total content of short-chain fatty acids (SCFA) in calf feces, as well as the proportions of isobutyric acid and butyric acid relative to total SCFA. In addition, the relative abundance of Subdoligranulum and Faecalibacterium was significantly increased in the feces of calves fed BCFA-DFL at 14 d of age, and Prevotella_9 was the first to appear in the BCFA group at 14 d of age. Overall, this study explored the effect of BCFA-DFL on the health status of calves in the early stage of their lives, laying a foundation for the research on BCFA-DFL in terms of the intestinal health of young ruminants.