Zhenming Zhou

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.

In vitro rumen gas production experiment was conducted with 57 kinds of feedstuff, which were categorized into energy feed, protein feed, and roughage, collected within China. Eight mathematical models were employed to describe the kinetics of in vitro rumen gas production. The results found that for energy feeds, protein feeds, and roughages, respectively, Michaelis–Menten (MM) or Logistic-Exponential with lag (LEL), MM, and Mitscherlich (MIT) exhibited the highest or shown no significant difference compared to the highest coefficient of determination (R²) (P < 0.05) for all categories of feed. Furthermore, regression estimation of intercept and slope for regression estimates of intercept and slope for Observed versus Predicted of aforementioned models shown no significant difference from 0 and 1, respectively (P < 0.05), except LEL for energy feed. Mean absolute error (MAE), root mean squared error of prediction (RMSEP), mean squared error of prediction (MSEP) of those models were relatively lower, with minimal systematic bias and regression bias. Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) rankings were higher compared with other models. Given these results, in studies where feedstuff categories are not distinguished or multiple feedstuffs categories are included, the MM model proves to be a good choice. MM or LEL was considered to better fit energy feedstuffs. The MM model was the optimal choice for fitting protein feedstuffs. MIT provided the best accuracy and moderate precision when fitting roughages.

The aim of this experiment is to explore the effect of sodium sulfate (Na₂SO₄) on methane reduction in the rumen, and its impact on anaerobic methane-oxidizing archaea (ANME). Using mixed rumen fluid from four Angus cattle fistulas, this study conducted an in vitro fermentation. Adding Na₂SO₄ to the fermentation substrate resulted in sulfur concentrations in the substrate of 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, and 2.4%. The gas production rate and methane yield were measured using an in vitro gas production method. Subsequently, the fermentation fluid was collected to determine the fermentation parameters. The presence of ANME in the fermentation broth, as well as the relationship between the number of bacteria, archaea, sulfate reducing bacteria (SRB), ANME, and the amount of Na₂SO₄ added to the substrate, were measured using qPCR. The results showed that: (1) the addition of Na₂SO₄ could significantly reduce CH₄ production and was negatively correlated with CO₂ production; (2) ANME-1 and ANME-2c did exist in the fermentation broth; (3) the total number of archaea, SRB, ANME-1, and ANME-2c increased with the elevation of Na₂SO₄. The above results indicated that Na₂SO₄ could mitigate methane production via sulfate-dependent anaerobic methane oxidation (S-DAMO) in the rumen. In the future management of beef cattle, including sodium sulfate in their diet can stimulate S-DAMO activity, thereby promoting a reduction in methane emissions.

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.

Guanidinoacetic acid (GAA) functions as a precursor for creatine synthesis in the animal body, and maintaining ample creatine reserves is essential for fostering rapid growth. This study aimed to explore the impact of GAA supplementation on growth performance, rumen fermentation, blood indices, nutrient digestion, and nitrogen metabolism in Angus steers through two experiments: a feeding experiment (Experiment 1) and a digestive metabolism experiment (Experiment 2). In Experiment 1, thirty-six Angus steers (485.64 ± 39.41 kg of BW) at 16 months of age were randomly assigned to three groups: control (CON), a conventional dose of GAA (CGAA, 0.8 g/kg), and a high dose of GAA (HGAA, 1.6 g/kg), each with twelve steers. The adaptation period lasted 14 days, and the test period was 130 days. Weighing occurred before morning feeding on days 0, 65, and 130, with rumen fluid and blood collected before morning feeding on day 130. Experiment 2 involved fifteen 18-month-old Angus steers (575.60 ± 7.78 kg of BW) randomly assigned to the same three groups as in Experiment 1, with a 7-day adaptation period and a 3-day test period. Fecal and urine samples were collected from all steers during this period. Results showed a significantly higher average daily gain (ADG) in the CGAA and HGAA groups compared to the CON group (p = 0.043). Additionally, the feed conversion efficiency (FCE) was significantly higher in the CGAA and HGAA groups than in the CON group (p = 0.018). The concentrations of acetate and the acetate:propionate ratio were significantly lower in the CGAA and HGAA groups, while propionate concentration was significantly higher (p < 0.01). Serum concentration of urea (UREA), blood ammonia (BA), GAA, creatine, and catalase (CAT) in the CGAA and HGAA groups were significantly higher than in the CON group, whereas malondialdehyde (MDA) concentrations were significantly lower (p < 0.05). Digestibility of dry matter (DM) and crude protein (CP) and the nitrogen retention ratio were significantly higher in the CGAA and HGAA groups than in the CON group (p < 0.05). In conclusion, dietary addition of both 0.8 g/kg and 1.6 g/kg of GAA increased growth performance, regulated rumen fermentation and blood indices, and improved digestibility and nitrogen metabolism in Angus steers. However, higher doses of GAA did not demonstrate a linear stacking effect.

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.

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.