Effects of Milk Replacer-Based Lactobacillus on Growth and Gut Development of Yaks' Calves: a Gut Microbiome and Metabolic Study

Abstract

The gut microbiota and its metabolic activities are crucial for maintaining host homoeostasis and health, of which the role of probiotics has indeed been emphasized. The current study delves into the performance of probiotics as a beneficial managemental strategy, which further highlights their impact on growth performance, serologic investigation, gut microbiota, and metabolic profiling in yaks' calves. A field experiment was employed consisting of 2 by 3 factorial controls, including two development stages, namely, 21 and 42 days (about one and a half month), with three different feeding treatments. Results showed a positive impact of probiotic supplements on growth performance by approximately 3.16 kg (P < 0.01) compared with the blank control. Moreover, they had the potential to improve serum antioxidants and biochemical properties. We found that microorganisms that threaten health were enriched in the gut of the blank control with the depletion of beneficial bacteria, although all yaks were healthy. Additionally, the gut was colonized by a microbial succession that assembled into a more mature microbiome, driven by the probiotics strategy. The gut metabolic profiling was also changed significantly after the probiotic strategy, i.e., the concentrations of metabolites and the metabolic pattern, including enrichments in protein digestion and absorption, vitamin digestion and absorption, and biosynthesis of secondary metabolites. In summary, probiotics promoted gut microbiota/metabolites, developing precise interventions and achieving physiological benefits based on intestinal microecology. Hence, it is important to understand probiotic dietary changes to the gut microbiome, metabolome, and the host phenotype. IMPORTANCE The host microbiome is a composite of the trillion microorganisms colonizing host bodies. It can be impacted by various factors, including diet, environmental conditions, and physical activities. The yaks' calves have a pre-existing imbalance in the intestinal microbiota with an inadequate feeding strategy, resulting in poor growth performance, diarrhea, and other intestinal diseases. Hence, targeting gut microbiota might provide a new effective feeding strategy for enhancing performance and maintaining a healthy intestinal environment. Based on the current findings, milk replacer-based Lactobacillus feeding may improve growth performance and health in yaks' calves.

Keywords: Lactobacillus; gut development; metabolomics; microbiome; yak calf.

FIG 1

Body weight and serum antioxidant properties of yaks’ calves, supplemented with LAB in three different groups. (A) yaks’ calves. (B) Initial and final body weight of calves. (C) Serum antioxidant properties of 21-day-old calves. (D) Serum antioxidant properties of 42-day-old calves. *, P < 0.05; **, P < 0.01.

FIG 2

Effects of LAB-MR supplementation on serum biochemical indexes and alpha diversity of gut microbiome in three different groups. (A) Alpha diversity of 21-day-old calves. (B) Alpha diversity of 42-day-old calves. (C) Serum biochemical indexes of 21-day-old calves. (D) Serum biochemical indexes of 42-day-old calves. *, P < 0.05; **, P < 0.01.

FIG 3

Effects of LAB-MR supplementation on gut bacterial communities’ structures. (A) Rarefaction curve; (B) rank abundance curve; (C) species accumulate curve; (D, E) represent the microbial similarity between groups by using PCoA scatter plot and UPGMA, respectively; (F, G) represent the analysis of microbial communities’ structures at the phylum and genus levels, respectively.

FIG 4

Significant differences in the relative abundance of gut microbiota among three different groups at phylum and genus levels. *, P < 0.05; **, P < 0.01.

FIG 5

Different metabolic patterns among three different groups. OPLS-DA score plot of gut metabolome in the ESI+ (A, B) and ES− modes (C, D). The permutation test for OPLS-DA in the ESI+ (E, F) and ES− modes (G, H) demonstrated the reliability of current OPLS-DA model. PCA score plot in the ESI+ (I, J) and ES− modes (K, L) assessed the metabolites’ similarity between groups.

FIG 6

Differential gut metabolites and metabolic pathways driven by LAB-MR supplementation. The metabolic pathways that were significantly changed in the ESI+ (A, B) and ES− modes (C, D). Volcano map showed the metabolites that were significantly up- or down- abundant driven by LAB-MR supplement in the ESI+ (E, F) and ES− modes (G, H).

FIG 7

Potential correlations between LAB-MR strategy-linked microbes and metabolites in the ESI1 and ES2 modes. (A, B) Represented covariation associations between FC and FW groups. (C, D) represented covariation associations between FM and FW groups.