Branched-chain fatty acids derived from lanolin supplementation in early life Holstein dairy calves modulate growth performance, digestibility, blood metabolites, and intestinal health

This study was conducted to explore the effects of branched-chain fatty acids derived from lanolin (BCFAs-DFL) on growth performance, digestibility, blood metabolites, intestinal development, and fecal bacterial structure of calves aged 0 ~28 d. Twenty-four newborn Holstein dairy calves [birth weight = 41.88 ± 4.56 kg, mean ± SD] were divided into the control group (Control) receiving whole milk without BCFAs-DFL and the treatment group (BCFA) receiving whole milk with BCFAs-DFL (4g/d) supplementation according to the randomized block design based on their birth weight and birth date. Calves fed BCFAs-DFL had higher ADG, feed efficiency, heart girth, and total-tract apparent digestibility of nutrients, while the treatments did not affect total DMI. Plasma cholesterol and haptoglobin were lower in calves fed BCFAs-DFL than in the control group. BCFAs-DFL 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 BCFAs-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 BCFAs significantly elevated the total content of short-chain fatty acids (SCFAs) in calf feces, as well as the proportions of isobutyric acid and butyric acid relative to total SCFAs. In addition, the relative abundance of Subdoligranulum and Faecalibacterium was significantly increased in the feces of calves fed BCFAs-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 impact of BCFAs-DFL on the health status of calves in the early stage of their lives, laying a foundation for the research on BCFAs-DFL in terms of the intestinal health of young ruminants.