Effects of milk replacer feeding level on growth performance, rumen development and the ruminal bacterial community in lambs

Influence of different amounts of milk replacer on esophageal leakage, rumen fermentation characteristics, gastrointestinal tract passage rate, and microbial crude protein synthesis of nursling animals

We aimed to evaluate the esophageal leakage, ruminal fermentation characteristics, passage rate, and microbial crude protein (MCP) synthesis and its flow in the immature rumen of preweaning animals fed different amounts of liquid diet. Sixty newborn male kids, not castrated, from Saanen and Swiss Alpine breeds, with BW of 3.834 ± 0.61 kg (mean ± SD), were distributed in a randomized block design in a 2 × 6 factorial scheme composed of 2 nutritional plans (either 1 L or 2 L of milk replacer [MR] per kid per day), and 6 time points of slaughter after feeding. Breeds were the blocking factor in the model (random effect). All kids were slaughtered at 45 d of life. Esophageal leakage was not affected by the nutritional plan. Esophageal leakage into the rumen averaged 56.0%, whereas 42.0% leaked directly into the abomasum. Furthermore, a low proportion (2.0%) of the MR escaped immediately into the small intestine. Passage rates were also not affected by the nutritional plan (P > 0.050). Milk replacer passage rates were 0.290 h-1, 0.307 h-1, and 0.369 h-1, and their respective mean retention times were 3.44 h, 3.22 h, and 6.06 h in the kids' rumen, abomasum, and small intestine, respectively. Microbial crude protein synthesis was not affected by the nutritional plan, averaging 1.95 (g/day) for the kids. Lastly, most ruminal fermentation characteristics were affected by the nutritional plans and slaughter time after feeding, such as ammonia, soluble protein, and VFA. In conclusion, a high MR allowance influences performance and rumen parameters without affecting esophageal leakage, passage rates, and MCP synthesis in preweaning dairy kids.

Enhancing Holstein steers growth performance: oregano essential oil's impact on rumen development, functionality and microorganism

BACKGROUND

Dietary supplementation with oregano essential oil (OEO), a natural plant extracts, is an effective and acceptable method to improve growth, beef quantity and quality, but the undergoing mechanism in rumen has not yet been reported in Holstein steers. This study investigated the effects of oregano essential oil (OEO) on growth performance, fermentation parameters, digestive enzymes activity, rumen development and microbiota in Holstein steers. Eighteen steers were randomly divided into two groups (n = 9) and fed either a basal diet (CCK) or the same diet supplemented with 20 g/(d·head) OEO (CEO) for 270 days.

RESULTS

OEO increased the rumen contents of volatile fatty acids (VFA, acetate (P = 0.011), propionate (P = 0.008), butyrate (P = 0.018)) and digestive enzymes activity (cellulase (P = 0.018), protease and β-glucosidase (P < 0.001)), and improved rumen development (papillae width (P = 0.008) and micropapillary density (P = 0.001)), which reasons contribute to increase body weight (BW, P = 0.022), average daily gain (ADG, P = 0.021), carcass weight (P = 0.001), dressing percentage (P < 0.001), and net meat production (P = 0.001) of steers. Meanwhile, metagenomic and metabolomic analysis revealed OEO significantly reduced abundance of rumen microorganisms, especially methanogenic archaea and viruses while beneficial bacteria (Bifidobacterium) and virulence factors were not affected. KEGG analysis revealed that OEO significantly reduces the host risk of disease, improves the digestive system, and reduces the energy basic metabolism level. A correlation analysis indicated fourteen kinds key microbiome and six downregulated metabolites interfere with each other and together influence the growth performance of steers.

CONCLUSION

These results suggest that feed with 20 g/(d·head) OEO in steers diets could improve growth performance, and reduces virus abundance and disease risk. And the findings provide fundamental insights into OEO, as an alternative source of natural bioactive compounds, how effect on rumen development, composition and function of microorganisms.

Microbial insights into ruminal fiber degradation and feed efficiency of Hu sheep

Ruminal fiber degradation is essential for feed conversion efficiency in sheep; however, it remains unclear whether individual variations in ruminal fiber degradation directly affect feed conversion efficiency. Here, the relationship between ruminal fiber degradation rate and feed conversion efficiency and influence of rumen structure, function, and microbiota on fiber degradation were investigated. A total of 190 male Hu lambs were randomly selected, raised from birth to 180 days, and slaughtered. The relationships between ruminal fiber degradation rate and feed conversion efficiency, growth performance, and ruminal fermentation parameters were analyzed. Key microorganisms influencing ruminal fiber degradation were identified using multiple methods: microbial wide association study, correlation analysis, and differential abundance analysis. Both neutral detergent fiber (NDF) and acid detergent fiber (ADF) degradation rates were significantly correlated with feed conversion efficiency and intake. Seven genera were closely associated with NDF degradation rate: 6 belonged to Firmicutes (Anaerotruncus, Family_XIII_UCG-002, Lachnoclostridium_1, Moryella, Ruminococcaceae_NK4A214_group, and Veillonellaceae_UCG-001); 1, Bacteroidetes (Prevotellaceae_UCG-003). Eight genera were closely associated with ADF degradation rate: 6, Firmicutes (Lachnospiraceae_ND3007_group, Family_XIII_UCG-002, Lachnoclostridium_1, Lachnospiraceae_UCG-002, Moryella, and Ruminococcaceae_NK4A214_group); 1, Bacteroidetes (Prevotellaceae_UCG-003); and 1, Actinobacteria (Olsenella). In conclusion, high ruminal fiber degradation rates significantly enhance feed conversion efficiency, with specific microbial genera from the phylum Firmicutes and family Lachnospiraceae playing pivotal roles in fiber utilization. These findings provide a microbial basis for optimizing rumen fiber degradation efficiency in sheep and highlight the potential of uncultured taxa as future targets for improving feed conversion efficiency.

Oregano essential oil enhanced body weight and well-being by modulating the HPA axis and 23-nordeoxycholic acid of cecal microbiota in Holstein steers under cold stress

BACKGROUND

Prolonged exposure to cold stress in cattle increases basal energy consumption and impedes optimal production. Consequently, herds require adequate attention during cold, extended winters to alleviate cold stress and maintain profitability. This study investigated the effects of oregano essential oil (EO) on body weight (BW), well-being, blood parameters, and cecal microbiota. Eighteen steers were randomly divided into two groups (n = 9) and fed either a basal diet (CK) or the same diet supplemented with 20 g/(d·head) EO for 270 days.

RESULTS

EO increased BW by increasing cecal microbial abundance and carbohydrate metabolism CAZymes, leading to elevated the total volatile fatty acids (VFA) levels. Cold stress activated the HPA axis, and mitigated stress by reducing serum levels of cortisol (COR), corticosterone (CORT), adrenocorticotropic hormone (ACTH), and dopamine (DA). EO increased well-being by decreasing viral species without apparent contribution to drug or antibiotic resistance development, and cecal metabolites were primarily enriched in growth, carbohydrate metabolism, and amino acid metabolism pathways. Specifically, tryptophan metabolism (2-picolinic acid, quinolinic acid, and oxindole) enhanced steer well-being by increasing antioxidants (superoxide dismutase (SOD), peroxidases (POD), and glutathione (GSH)) and reducing inflammatory factors (interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)) following EO treatment. Notably, low-abundance microorganisms (s_Streptomyces_gardneri, s_Paenibacillus_sp._S09, and s_Nocardia_sp._Root136) may play a significant role in growth and immunity.

CONCLUSION

These findings provide fundamental insights into how EO alleviates cold stress by modulating the HPA axis, promotes growth and well-being of steers under cold stress by influencing mediates tryptophan metabolism of cecal microbiota in Holstein steers.

The characteristics, influence factors, and regulatory strategies of growth retardation in ruminants: a review

Growth retardation represents a main barrier to affect the productivity and efficiency of ruminants production, which is characterized by low growth rate, a disparity between skeletal and physiological maturation, gastrointestinal dysfunction and reduced reproductive performance. This review provides a concise overview of growth retardation in ruminants, and summarizes the key factors that influence their growth and development, including genetics, nutrition, microbiota and environment. Also, this review emphasizes the central role of nutritional management and gastrointestinal development, as well as the regulatory mechanisms involved in growth processes. In addition, recent advances in these aspects are discussed to form an integrative framework aimed at improving physiological function in ruminants. This review provides a comprehensive perspective for understanding the complex mechanism of growth retardation in ruminants, puts forward a theoretical basis for optimizing the production efficiency of ruminants industry and emphasizes the importance of multidisciplinary collaboration to provide a reference for advancing systematic research on growth and development of ruminants.

Interactions between rumen epithelium-associated microbiota and host immunological and metabolic adaptations in response to different milk replacer feeding intensities in dairy calves

The milk replacer feeding regime in dairy calves has a great impact on metabolic and immunological functioning and affects animal welfare and lifetime performance. The feeding regime influences the rumen microbial composition, and epithelium-associated microbes may interact with the immune system of the host. We examined the correlations between blood leukocyte counts and the rumen epithelium-associated microbiome in dairy calves fed 2 different milk replacer feeding intensities and if these factors related to metabolic traits. Fourteen newborn female dairy calves were allocated to a group receiving either 10% (n = 7) or 20% (n = 7) milk replacer of their body weight (on average 41 kg) and provided ad libitum access to grass hay and concentrate pellets. At 3 weeks of life, all calves were fitted with a rumen cannula. Calves were weaned at 12 weeks of life and received a total mixed ration for ad libitum intake. Pre- (8-10 weeks of life) and post-weaning (21-23 weeks of life), methane production was measured in respiration chambers, and rumen epithelium and blood were sampled for 16S rRNA sequencing and leukocyte analyses, respectively. Pre-weaning, the reduced milk replacer feeding intensity was accompanied with higher concentrate intake but lower growth performance (P < 0.001), a higher abundance of amylolytic and lower abundance of cellulolytic epimural microbes. The group fed a low milk replacer intensity had also greater portions of monocytes (P = 0.031), CD8+ (P < 0.001), and CD14+ (P = 0.044) leukocytes, suggesting elevated inflammatory conditions. Correlations between CD8+ T cells and rumen methanogens, Ruminococcaceae, and Lachnospiraceae were recorded, but these were not consistent throughout maturation. Post-weaning, differences in feed intake and rumen microbial composition converged among milk replacer groups, while differences in growth performance (P = 0.040) and CD8+ cells (P < 0.001) were still present. In conclusion, a reduced milk replacer feeding intensity in dairy calves compromised growth performance and immunity and this effect persisted in the long-term. Significant correlations between the proportion of leukocytes and distinct epimural microbe taxa indicated an interplay between rumen epimural colonization and immune functioning of the host. However, further research is required addressing this interplay between rumen epimural microbes and immune functioning in dairy calves.

Early-life milk replacer feeding mediates lipid metabolism disorders induced by colonic microbiota and bile acid profiles to reduce body weight in goat model

BACKGROUND

Dysregulation of lipid metabolism and its consequences on growth performance in young ruminants have attracted attention, especially in the context of alternative feeding strategies. This study aims to elucidate the effects of milk replacer (MR) feeding on growth, lipid metabolism, colonic epithelial gene expression, colonic microbiota composition and systemic metabolism in goat kids compared to breast milk (BM) feeding, addressing a critical knowledge gap in early life nutrition.

METHODS

Ten female goat kids were divided into 2 groups: those fed breast milk (BM group) and those fed a milk replacer (MR group). Over a period of 28 d, body weight was monitored and blood and tissue samples were collected for biochemical, transcriptomic and metabolomic analyses. Profiling of the colonial microbiota was performed using 16S rRNA gene sequencing. Intestinal microbiota transplantation (IMT) experiments in gnotobiotic mice were performed to validate causality.

RESULTS

MR-fed pups exhibited reduced daily body-weight gain due to impaired lipid metabolism as evidenced by lower serum and liver total cholesterol (TC) and non-esterified fatty acid (NEFA) concentrations. Transcriptomic analysis of the colonic epithelium revealed upregulated genes involved in negative regulation of lipid metabolism, concomitant with microbiota shifts characterized by a decrease in Firmicutes and an increase in Actinobacteria. Specifically, genera such as Bifidobacterium and Prevotella were enriched in the MR group, while Clostridium and Faecalibacterium were depleted. Metabolomics analyses confirmed alterations in bile acid and fatty acid metabolic pathways. IMT experiments in mice recapitulated the metabolic phenotype observed in MR-fed goats, confirming the role of the microbiota in modulating host lipid metabolism.

CONCLUSIONS

Milk replacer feeding in goat kids disrupts lipid metabolism and gut microbiota dynamics, resulting in reduced growth rates and metabolic alterations. These findings highlight the importance of early nutritional intervention on metabolic programming and suggest that modulation of the gut microbiota may be a target for improving growth and metabolic health in ruminants. This study contributes to the understanding of nutritional management strategies in livestock and their impact on animal health and productivity.

Exploring the Rumen Microbiota and Serum Metabolite Profile of Hainan Black Goats with Different Body Weights before Weaning

The critical role of the rumen microbiota in the growth performance of livestock is recognized, yet its significance in determining the body weight of goat kids before weaning remains less understood. To bridge this gap, our study delved into the rumen microbiota, serum metabolome, rumen fermentation, and rumen development in goat kids with contrasting body weights before weaning. We selected 10 goat kids from a cohort of 100, categorized into low body weight (LBW, 5.56 ± 0.98 kg) and high body weight (HBW, 9.51 ± 1.01 kg) groups. The study involved sampling rumen contents, tissues, and serum from these animals. Our findings showed that the HBW goat kids showed significant enrichment of VFA-producing bacteria, particularly microbiota taxa within the Prevotellaceae genera (UCG-001, UCG-003, and UCG-004) and the Prevotella genus. This enrichment correlated with elevated acetate and butyrate levels, positively influencing rumen papillae development. Additionally, it was associated with elevated serum levels of glucose, total cholesterol, and triglycerides. The serum metabonomic analysis revealed marked differences in fatty acid metabolism between the LBW and HBW groups, particularly in encompassing oleic acid and both long-chain saturated and polyunsaturated fatty acids. Further correlational analysis underscored a significant positive association between Prevotellaceae_UCG-001 and specific lipids, such as phosphatidylcholine (PC) (22:5/18:3) and PC (20:3/20:1) (r > 0.60, p < 0.05). In summary, this study underscores the pivotal role of the rumen microbiota in goat kids' weight and its correlation with specific serum metabolites. These insights could pave the way for innovative strategies aimed at improving animal body weight through targeted modulation of the rumen microbiota.

Transcriptome Analysis to Elucidate the Effects of Milk Replacer Feeding Level on Intestinal Function and Development of Early Lambs

Although early feeding strategies influence intestinal development, the effects of milk replacer (MR) feeding level on intestinal structure and functional development and underlying regulatory mechanisms remain unclear. In this study, 14 male Hu lambs were fed MR at 2% or 4% of their average body weight and weaned at 35 days of age. The MR was produced by the Institute of Feed Research of the Chinese Academy of Agricultural Sciences, and it contains 96.91% dry matter, 23.22% protein, and 13.20% fat. Jejunal tissues were assessed by RNA-seq for differences in the gene expression of lambs at 49 days of age; regulatory pathways and mechanisms of the effects of early nutrition on intestinal function and development were analyzed, along with growth performance, feed intake, jejunal histomorphology, and digestive enzyme activities. Increasing MR- feeding levels increased dry matter intake and daily gain before weaning, as well as lactase, amylase, lipase, trypsin, and chymotrypsin activities and intestinal villus length and muscular thickness. Overall, 1179 differentially expressed genes were identified, which were enriched in nutrient metabolism, coagulation cascades, and other pathways. Further, intensive MR feeding affected insulin sensitivity to reduce excessive glucose interception by intestinal tissues to ensure adequate absorbed glucose release into the portal circulation and promoted lipid and protein degradation in intestinal tissues to meet the energy demand of intestinal cells by regulating AHSG, IGFBP1, MGAT2, ITIH, and CYP2E1 expression.