Capsaicin (CAP) and Yucca schidigera extract (YSE) are two types of plant extracts that can change rumen fermentation. This study was conducted to investigate whether supplementation of beef cattle diets with CAP and YSE for 90 days would affect rumen fermentation and microflora. Forty-five healthy Angus steers (initial body weight = 510.54 ± 41.27 kg) were divided into three groups: control (CON), CAP, and YSE. Ammonia nitrogen (NH₃-N) and total volatile fatty acid (TVFA) concentrations were significantly higher in the YSE group than in the CON group and significantly lower in the CAP group than in the CON group. At the phylum level, YSE increased the relative abundances of Bacteroidota and Patescibacteria and reduced that of Bacillota. At the genus level, CAP and YSE both increased the relative abundances of genera subordinate to Bacteroidota and decreased the relative abundances of genera subordinate to Bacillota. Our study shows that YSE and CAP have different effects on rumen fermentation and microflora after long-term supplementation.

Neonatal calf diarrhea (NCD) is a broad symptom encompassing many potential underlying causes. While alterations in the gut microbiota have been correlated with diarrhea, the effects of diarrhea on gut communities have not been sufficiently studied. To explore these effects and identify key microbiota involved, we profiled the fecal microbial community of 21 calves with varying health conditions using the 16S rRNA gene. In comparison to healthy calves, diarrheic calves exhibited significantly decreased diversity and evenness indices. There was a notable increase in the relative abundance of Proteobacteria and Actinobacteriota, and a significant decrease in the relative abundance of Bacteroidetes. At the genus level, there were increased relative abundances of Escherichia-Shigella and Lactobacillus. Notably, the abundance of Lactobacillus continued to increase during the recovery from diarrhea. Clinical observation and bacterial typing analysis revealed fecal microbiome dysbiosis as a significant characteristic of NCD. This work identifies dysbiosis as a key factor promoting diarrhea in neonatal calves, characterized by a low-diversity microbiome. The increased abundance of Lactobacillus might contribute to the curative properties of diarrhea.

Guanidinoacetic acid (GAA) has been used in ruminant feeding, but it is still unclear whether the exogenous addition of methyl donors, such as methionine (Met), can enhance the effects of GAA. This study investigated the effects of dietary GAA alone or combined with Met on beef cattle growth performance and explored the underlying mechanisms via blood analysis, liver metabolomics, and transcriptomics. Forty-five Simmental bulls (453.43 ± 29.05 kg) were assigned to three groups for 140 days: CON (control), GAA (0.1% GAA), and GAM (0.1% GAA + 0.1% Met), where each group consisted of 15 bulls. Compared with the CON group, the average daily gain (ADG) and feed conversion efficiency (FCE) of the two feed additive groups were significantly increased, and the digestibility of neutral detergent fiber (NDF) was improved (p < 0.05). Among the three treatment groups, the GAM group showed a higher rumen total volatile fatty acids (TVFAs) content and digestibility of dry matter (DM) and crude protein (CP) in the beef cattle. The serum indices showed that the contents of indicators related to protein metabolism, lipid metabolism, and creatine metabolism showed different increases in the additive groups (p < 0.05). It is worth noting that the antioxidant indexes in the serum and liver tissues of beef cattle in the two additive groups were significantly improved (p < 0.05). The liver metabolites related to protein metabolism (e.g., L-asparagine, L-glutamic acid) and lipid metabolism (e.g., PC (17:0/0:0)) were elevated in two additive groups, where Met further enhanced the amino acid metabolism in GAM. In the two additive groups, transcriptomic profiling identified significant changes in the expression of genes associated with protein metabolism (including PIK3CD, AKT3, EIF4E, HDC, and SDS) and lipid metabolism (such as CD36, SCD5, ABCA1, APOC2, GPD2, and LPCAT2) in the hepatic tissues of cattle (p < 0.05). Overall, the GAA and Met supplementation enhanced the growth performance by improving the nutrient digestibility, serum protein and creatine metabolisms, antioxidant capacity, and hepatic energy and protein and lipid metabolisms. The inclusion of Met in the diet was shown to enhance the nutrient digestibility and promote more efficient amino acid metabolism within the liver of the beef cattle.

This study investigates the impact of varying concentrate levels in the diets of Angus beef cattle on their performance, nutrient digestion, and metabolism during the growth (7 to 12 months) and fattening (13 to 30 months) phases. Fifteen Angus steers were continuously fed and divided into low-concentrate (L) and high-concentrate (H) groups based on the fattening period and dietary formulations. Throughout each 9-week trial phase, a comprehensive range of parameters was systematically measured, including dry matter intake (DMI), average daily gain (ADG), gain-to-feed ratio (G/F), blood parameters, rumen fluid composition, and microbial diversity. In the fattening phases, an increase in concentrate levels resulted in a significant rise in the cattle’s DMI. Although there was a minor increase in ADG compared to the growing phases, this increase was not statistically significant. The efficiency of nitrogen (N) utilization in the cattle decreased, accompanied by a significant reduction in the apparent digestibility of nutrients. Ruminal fermentation produced more energy substances; however, there was a notable decrease in the abundance of fiber-decomposing microbes (such as the NK4A214_group, Ruminococcus, Papillibacter, and Acetitomaculum) and a significant increase in the abundance of starch-degrading microbes (including Bacteroidota and Prevotellaceae). Additionally, there was a significant reduction in the abundance of immune system-related functional pathways. This suggests that high-concentrate fattening does not necessarily lead to improved growth performance and may negatively affect metabolic health and nutrient digestion.

This study was conducted to explore the potential effect of Yucca schidigera extract (YSE) on the metabolism of beef cattle. Thirty Angus crossbreed steers were selected, with an initial mean body weight of 506.6 ± 33.3 kg, and assigned to two treatments: a diet with no additives (CON group) and a diet supplemented with 1.75 g/kg of YSE (YSE group) (on a dry matter basis). The experiment lasted for 104 days, with 14 days for adaptation. The results showed that adding YSE could significantly improve the average daily gain (ADG) from 1 to 59 d (15.38%) (p = 0.01) and 1 to 90 d (11.38%) (p < 0.01), as well as dry matter digestibility (DMD) (0.84%) (p < 0.05). The contents of alanine aminotransferase, aspartate aminotransferase, and bilirubin and the total antioxidant capacity were increased and blood urea was reduced in the YSE group, compared to the CON group (p < 0.05). Both the glycerophospholipids and bile acids, including phosphocholine, glycerophosphocholine, PC(15:0/18:2(9Z,12Z)), PE(18:0/20:3(5Z,8Z,11Z)), PE(18:3(6Z,9Z,12Z)/P-18:0), LysoPC(15:0), LysoPC(17:0), LysoPC(18:0), LysoPC(20:5(5Z,8Z,11Z,14Z,17Z)), deoxycholic acid, glycocholic acid, and cholic acid, were upregulated by the addition of YSE. In summary, YSE may improve the ADG by increasing the blood total antioxidant capacity and glycerophospholipid synthesis, maintaining steers under a healthy status that is beneficial for growth. Furthermore, YSE may also increase the expression of bile acid synthesis, thereby promoting DMD, which, in turn, offers more nutrients available for growth.