Background: Hu sheep, a key meat breed introduced to Xinjiang, face growth inhibition and low feed efficiency due to challenges in adapting to the cold, arid climate and drastic seasonal temperature fluctuations in northern Xinjiang. Guanidinoacetic acid (GAA), a precursor of creatine, has been shown to enhance growth performance by optimizing energy metabolism and improving health by modulating immunity and antioxidant capacity. However, research on GAA in ruminants remains limited, and few mechanistic studies have addressed nutritional regulation strategies to optimize growth performance and stress resistance of Hu sheep under the harsh climatic conditions of northern Xinjiang, particularly regarding the efficacy of Rumen-protected Guanidinoacetic acid (RPGAA) in bypassing ruminal degradation to improve production performance. This study systematically evaluated the effects of the supplements of GAA and RPGAA in diet on growth performance, serum biochemistry, immunity, and antioxidant capacity in Hu sheep, aiming to elucidate metabolic regulatory mechanisms and provide theoretical and technical support for efficient Hu sheep farming.Methods: A total of sixty-three healthy Hu rams were randomly divided into three groups, each with three replicates and seven sheep per replicate pen. The three groups were as follows: Group I (control group with basal diet), Group II (basal diet + 1.0 g/kg GAA), and Group III (basal diet + 1.0 g/kg RPGAA).Results: Compared to the control, RPGAA increased final body weight and average daily gain (P<0.01), with a lower feed-to-gain ratio than GAA (P<0.01). Both supplements enhanced feed intake (P<0.01), but RPGAA showed superior nutrient utilization efficiency. Serum biochemical analyses revealed that RPGAA significantly elevated glucose (P<0.01), albumin (P<0.01), and albumin-to-globulin ratio (P<0.01), while reducing triglycerides (P<0.05) and cholesterol (P<0.05). GAA showed similar trends but with less pronounced effects. Immunologically, RPGAA increased IgG levels (P<0.05) and reduced pro-inflammatory cytokines (IFN-γ, IL-2; P<0.05). Antioxidant capacity improved in both groups, with RPGAA uniquely enhancing glutathione activity (P<0.05) alongside increased SOD, T-AOC, and CAT activities (P<0.05) and reduced MDA (P<0.05).Conclusion: Dietary supplementation with 1.0 g/kg guanidinoacetic acid (GAA) or rumen-protected GAA (RPGAA) significantly enhances growth performance, nutrient metabolism, antioxidant capacity, and immune function in Hu sheep while mitigating inflammation in northern Xinjiang region. By circumventing ruminal degradation, RPGAA demonstrates superior efficacy over conventional GAA, as evidenced by improved feed efficiency, enhanced serum biochemical profiles (e.g., glucose, albumin), elevated immunoglobulin G (IgG), and unique augmentation of glutathione (GSH) activity. These findings establish RPGAA as an innovative nutritional strategy to optimize production efficiency and stress resilience in ruminants under challenging environmental conditions, offering practical insights for high-performance sheep farming in arid and cold climates.

Introduction: Guanidinoacetic acid (GAA), the direct precursor of creatine, has been shown to improve growth performance in monogastric animals, but its metabolic effects in ruminants remain unclear. This study examined whether dietary GAA and rumen-protected GAA (RPGAA) are associated with changes in intestinal creatine-related metabolism, portal nutrient concentrations, and hepatic IGF-1 expression in Hu sheep. Methods: Twenty-seven Hu rams were randomly assigned to three treatments for 45 days: a basal diet (control), the basal diet supplemented with 1.0 g/kg GAA, or the basal diet supplemented with 1.0 g/kg RPGAA. Growth performance, intestinal mucosal GAA and creatine concentrations, expression of genes related to creatine metabolism and nutrient transport, portal blood nutrient concentrations, serum biochemical variables, and hepatic IGF-1 indices were determined. Results: RPGAA significantly increased final body weight and average daily gain and decreased feed-to-gain ratio ( p < 0.05). RPGAA increased GAA and creatine concentrations in the jejunal mucosa, downregulated AGAT mRNA expression, and upregulated transporter-related genes ( p < 0.01). These changes were accompanied by higher concentrations of glucose, arginine, methionine, and lysine in portal blood ( p < 0.05), as well as increased hepatic IGF-1 mRNA expression and IGF-1 concentration ( p < 0.01). In addition, serum glucose and albumin increased, whereas total cholesterol and bilirubin decreased in the RPGAA group ( p < 0.05). Discussion: These findings suggest that the improved growth performance induced by RPGAA is associated with enhanced jejunal GAA availability, portal nutrient concentrations, and hepatic IGF-1 expression in Hu sheep.

Background: Xinjiang is characterized by extremely cold weather and significant seasonal temperature variations, and these harsh climatic conditions have led to a high incidence of diarrhea and increased mortality rates among newborn calves, resulting in substantial economic losses for the local cattle industry. Saccharomyces boulardii cell wall polysaccharide (SBWP) is a natural prebiotic that has emerged as a promising alternative to conventional antibiotics for the mitigation of systemic inflammation, diarrhea, and mortality in livestock production. Therefore, this study aimed to investigate the effects of SBWP supplementation on growth performance, diarrhea frequency, serum immunity, and intestinal microbiota in newborn calves.Methods: In this study, a one-way experimental design was employed. A total of 45 newborn calves (Simmental♂ × Yili brown cattle♀, male, average body weight (BW) 35.58 ± 5.79 kg) were randomly allocated into five experimental groups. Each group consisted of three pens, with three calves per pen, and this allocation was carried out based on the percentage of SBWP used as a feed supplement. The diet for the five groups were as follows: group I received milk + basal diet without additives, group II received milk + basal diet + 0.005% gentamicin, group III received milk + basal diet + 250 mg/day/calf SBWP, group IV received milk + basal diet + 500 mg/day/calf SBWP, and group V received milk + basal diet + 1,000 mg/day/calf SBWP. Daily feed consumption was recorded, and BW was measured on days 1, 14, and 28 to calculate average daily gain (ADG), average daily feed intake, and feed-to-gain (F/G) ratio. Fecal samples were collected on days 1, 7, 14, 21, and 28 for microbiological analysis, and fecal scores were subjectively monitored and recorded daily by the same individual. In addition, blood samples were collected from each calf at the end of the trial for immune analysis.Results: In comparison to group I, group IV showed a significant increase in both BW and ADG. Specifically, on the 14th and 28th trial days, BW of group IV showed a significant increase of 3.95 and 4.90%, respectively (p < 0.05). Similarly, during the 1–28 trial day period, ADG of group IV showed a significant increase of 28.49% (p < 0.05), whereas their F/G ratio decreased significantly by 22.89% (p < 0.05). No statistically significant difference was observed in BW, ADG, dry matter intake, and F/G ratio (p > 0.05) between groups IV and II. In addition, the fecal score and the diarrhea rate in group IV were significantly reduced by 31.62 and 18.54%, respectively (p < 0.05). No statistically significant difference was observed between groups IV and II (p > 0.05). Moreover, in group IV, IgG and IL-10 levels were significantly increased by 51.97 and 45.45%, respectively (p < 0.05), while IL-1, IL-6, and TNF-α levels were significantly decreased by 30.47, 28.17, and 25.49%, respectively (p < 0.05). Furthermore, a decreasing trend in the number of Escherichia coli and Clostridium perfringens was observed in the fecal microbiota samples obtained from group IV, whereas an increasing trend was observed in the growth of Lactobacillus and Bifidobacterium. Supplementing newborn calves with 500 mg of SBWP per day significantly enhanced the β-diversity indices and demonstrated a trend toward increasing α-diversity in their fecal microbiota, in contrast to the detrimental effects caused by 0.005% gentamicin. Furthermore, 500 mg/day/calf SBWP significantly increased the relative abundance of Lactobacillus and decreased the relative abundance of Escherichia-Shigella. However, no significant difference was observed in the relative abundance of Escherichia-Shigella between the groups receiving 500 mg/day/calf SBWP and 0.005% gentamicin.Conclusion: The findings of this study show that the supplementation of 500 mg/day/calf SBWP to newborn calves significantly improves their growth performance, serum immunity, and intestinal microbiota structure while significantly reducing diarrhea frequency and inflammation. These findings indicate that the supplementation of 500 mg/day/calf SBWP can most effectively enhance the growth performance and reduce the diarrhea frequency in newborn calves.

This study was conducted to investigate the effects of dietary supplementation with rumen-protected arginine (RP-Arg) on growth performance, rumen fermentation parameters, microbial diversity, and blood physiological and biochemical indices in fattening Altay sheep. A total of 24 healthy, 6-month-old Altay male lambs were randomly assigned to three groups, with eight replicates per group. The control group received a basal diet, while the experimental groups were supplemented with either 0.50% or 1.00% RP-Arg on a dry matter basis, respectively. The results indicated that RP-Arg supplementation had no significant effect on feed intake, growth performance, or slaughter performance of the lambs (p > 0.05), whereas backfat thickness decreased linearly (p < 0.05). With increasing RP-Arg levels, serum low-density lipoprotein cholesterol, leptin, and catalase activity increased linearly (p < 0.05), while blood ammonia, alanine aminotransferase, and Ig M exhibited a significant quadratic increase (p < 0.05). RP-Arg supplementation led to a linear decrease in ruminal propionate and valerate concentrations (p < 0.05). Analysis of bacterial diversity revealed that the class Vampirivibrionia and the order Gastranaerophilales were biomarkers for the 0.50% RP-Arg group, while several taxa within the phyla Proteobacteria and Thermoplasmatota served as biomarkers for the 1.00% RP-Arg group. In summary, although supplementation of a forage-based diet with RP-Arg partially modified rumen microbial composition and fermentation profile, and regulated several blood biochemical parameters, it did not translate into any beneficial effects on growth performance. Larger-scale studies are therefore warranted to further elucidate the role of RP-Arg in fattening lambs.

Background: The high rates of diarrhea, mortality, and feed conversion ratio (F/G) among weaned piglets have significantly hindered the development of pig feeding practices in Jinhua, located in the North Xinjiang region. Saccharomyces boulardii cell wall polysaccharide (SBWP) is a probiotic that has the potential to enhance gastrointestinal immunity and health, while also reducing systemic inflammation, diarrhea rates, and mortality. This study investigates the effects of SBWP on the performance, immune capacity, antioxidant capacity, and mucosal morphology of weaned piglets from Jinhua, North Xinjiang region, through a 28-day feeding trial.Methods: A total of 64 male weaned Jinhua piglets, aged 28 days and with a mean body weight of 4.23 ± 0.53 kg, were utilized in this study. The piglets were randomly assigned to four experimental groups, each consisting of four pens with four piglets per pen, based on varying percentages of SBWP as a feed supplement. The supplementation concentrations for the four groups were 0% (control group), 0.2%, 0.5%, and 1.0% of SBWP, respectively.Results: Compared to the CON group, the 0.5% and 1.0% SBWP groups demonstrated a increase in average daily feed intake (ADFI) and average daily gain (ADG), alongside a decrease in the feed-to-gain ratio (F/G). Additionally, the average fecal score and diarrhea frequency in the 0.5% and 1.0% SBWP groups were reduced, with no mortality recorded in these groups, which represented a 37.50% reduction compared to the CON group. In terms of ileal mucosal immunity, the 0.5% and 1.0% SBWP supplementation groups demonstrated reduced concentrations of pro-inflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), as well as diamine oxidase (DAO). Conversely, both groups exhibited significantly elevated concentrations of the anti-inflammatory cytokine interleukin-10 (IL-10). Furthermore, the addition of 0.5% and 1.0% SBWP significantly increased secretory immunoglobulin A (SIgA). In serum immunity, both SBWP groups had reduced concentrations of TNF-α, IL-1β, IL-6 and DAO. Regarding the antioxidant capacity of the ileal mucosa, the content of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in the 0.5% and 1.0% SBWP groups were decreased, while catalase (CAT), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) were increased, and superoxide dismutase (SOD) activity was enhanced. Lastly, the addition of 0.5% and 1.0% SBWP to the basal diet resulted in a promotion in villus height and the ratio of villus height to crypt depth (VCR), thereby improving the morphology of the ileal mucosa. In conclusion, the growth performance of weaned piglets from Jinhua in northern Xinjiang improved by 0.5-1.0% when supplemented with SBWP in the basal diet. This enhancement is attributed to the increased antioxidant capacity, improved immune function, enhanced mucosal morphology, and reduced concentrations of inflammatory factors in both the ileal mucosa and serum.

Introduction: Neonatal calves exhibit immature digestive and immune systems, rendering them susceptible to environmental stressors such as cold temperatures, which exacerbate gastrointestinal dysfunction and diarrhea incidence. Antibiotic use for mitigation poses risks, including microbiota disruption and resistance development, necessitating safe probiotic alternatives. Methods: This study evaluated the effects of Bacillus megaterium supplementation on growth performance, diarrhea occurrence, serum biochemical, immune, and antioxidant parameters, and rectal microbiota composition in neonatal calves under Xinjiang’s cold climate. Fifty crossbred calves were randomly assigned to five groups ( n = 10): basal diet (Group I), basal plus 50 mg/day gentamicin (Group II), or basal plus 250, 500, or 1,000 mg/day B. megaterium (Groups III–V). Supplementation occurred via milk over 28 days, with assessments of growth performance, fecal scores, serum indices, and rectal microbiota. Results and discussion: The 500 mg/day B. megaterium treatment (Group IV) significantly increased average daily gain (ADG) and reduced feed-to-gain ratio (F/G) and diarrhea frequency compared to control ( p < 0.05). Serum IgG increased, whereas pro-inflammatory cytokines (IL-1β, TNF-α, IFN-γ) decreased in the probiotic group compared with controls ( p < 0.05). Antioxidant capacity improved significantly, with GSH-Px and CAT elevated and MDA reduced ( p < 0.05). Rectal microbiota Shannon index was significantly higher in Group IV compared to the Group II (median: 2.7 vs. 3.8; p < 0.05). The relative abundance of Firmicutes increased, and beneficial genera ( Lactobacillus , Faecalibacterium , Ruminococcaceae_UCG-014 ) were enriched, whereas Escherichia–Shigella decreased in Group IV ( p < 0.05). Beneficial taxa were positively associated with immune and antioxidant markers and negatively associated with pro-inflammatory cytokines. Overall, these findings suggest that B. megaterium is a promising antibiotic alternative for promoting calf health, productivity, and beneficial gut microbiota under cold stress, with implications for more sustainable ruminant production systems.