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Simple Summary: This study investigated the effects of guanidinoacetic acid (GAA) supplementation on the growth performance, rumen fermentation, blood indices, nutrient digestion, and nitrogen metabolism of Angus steers. In a 130-day feeding experiment, steers receiving GAA at a conventional dose (0.8 g/kg) and a high dose (1.6 g/kg) exhibited significantly higher average daily weight gain and improved feed conversion efficiency compared to the control group without GAA. GAA supplementation also influenced rumen fermentation, with lower acetate levels, higher propionate levels, and higher acetate: propionate ratio in GAA groups. Blood analyses revealed elevated concentrations of urea, blood ammonia, GAA, creatine, and catalase, indicating improved creatine metabolism and antioxidant activity. A subsequent 3-day digestive metabolism experiment confirmed that the GAA-supplemented groups had increased dry matter and crude protein digestibility, as well as increased N retention and improved organismal nitrogen metabolism. In summary, dietary GAA supplementation at a 0.8 g/kg and 1.6 g/kg DM basis positively influenced growth performance, rumen fermentation, blood indices, nutrient digestion, and nitrogen metabolism in Angus steers, emphasizing its potential as a nutritional strategy. 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. [ABSTRACT FROM AUTHOR]

Simple Summary: Effect of high sulfur diet on digestion and morphology of the ruminant gastrointestinal tract was investigated both in vitro and in vivo. The results showed that, though sulfur level had little effect on rumen fermentation and most of the rumen microbials, sulfate-reducing bacteria (SRB) pop-ulation and sulfur metabolism had been changed, which led to inhibit methane emission. How-ever, high sulfur in the diet could increase risk of inflammation of rumen epithelium. These experiments were conducted to evaluate the effect of excessive sulfur on rumen fermentation, microflora, and epithelial barrier function in steers through in vitro gas production and animal feeding experiments. Nine and four levels of sulfur addition were evaluated in in vitro ruminal fermentation and animal feeding experiment, respectively. The results showed that increasing the level of sulfur in substrates decreased the total gas and methane production linearly, while increasing the production of hydrogen sulfide gas (p < 0.01). Volatile fatty acid concentrations, especially that of butyric acid, were increased by extra sulfur (p < 0.01). Sulfur content in the diet had no significant effect (p > 0.05) on most of the rumen microbes, except for Desulfovibrio, one of the major sulfate-reducing bacteria (SRB) in the rumen, whose population increased by adding extra sulfur (p < 0.001). The changes in the morphology of rumen epithelium and thickening of the total epithelial layer were mainly attributed to the increase in the acanthosis cell layer and stratum basale (p < 0.05). Further, the relative expressions of two tight junction protein regulating genes, CLDN-1 and TJP1, were reduced (p < 0.05). Excessive sulfur in the diet can change the type of rumen fermentation, sulfate metabolism and SRB population, and the rumen epithelial barrier function. The results of this study demonstrated that sulfur can be used as a methane inhibitor with the mechanism that SRB competitively used protons to produce hydrogen sulfide. However, a higher level of sulfur in the diet could increase the inflammatory reaction of the rumen epithelium which may affect nutrient absorption. [ABSTRACT FROM AUTHOR]

Simple Summary: Various methods such as in situ, gas production and enzymatic methods are exercised to estimate the in vivo fermentable organic matter (FOM). However, each of these methods has its limitations. The in vivo method with fistulated animals for FOM determination is expensive, laborious and negatively affects animal welfare. Similarly, the in situ method also requires rumen fluid and is costly. However, enzymatic methods eliminate the need for fistulated animals and are comparatively simple, cheaper, faster, have greater repeatability, and also ensure the standardization of the process. Additionally, in situ technique can be disregarded as a standard method to test the accuracy of other techniques in cases where in vivo testing is not feasible. Therefore, in the current study, we compared the in situ nylon bag technique with the in vitro neutral detergent cellulase method and chemical composition to estimate in vivo FOM of roughages. In Vivo fermentable organic matter (FOM) reflects the energy production and the potential of rumen's microbial protein synthesis. However, the in vivo method with fistulated animals for FOM measurement compromises animal welfare and is laborious as well as expensive. Although the alternative in situ nylon bag technique has been widely used, it is also costly and requires rumen liquor. Therefore, the present study was performed to compare the in situ nylon bag technique with the in vitro neutral detergent cellulase (NDC) method or chemical composition to estimate in vivo FOM of roughages. For this purpose, we selected 12 roughages, including six each from forages and crop residues. Our results have shown the strong correlation equations between FOMin situ and FOMNDC of forages (n = 6; R2 = 0.79), crop residues (n = 6; R2 = 0.80), and roughages (n = 12; R2 = 0.84), respectively. Moreover, there were also strong correlations between the chemical composition of roughages and FOMin situ (n = 12; R2 = 0.84–0.93) or FOMNDC (n = 12; R2 = 0.79–0.89). In conclusion, the in vitro NDC method and chemical composition were alternatives to in situ nylon bag technique for predicting in vivo FOM of roughages in the current experiment. [ABSTRACT FROM AUTHOR]

Simple Summary: Two corn hybrid types, dual-purpose and silage-specific, were harvested at the one half to three fourths milk line and ensiled in fermentation bags for 60 days. Parameters such as fermentation quality, chemical composition, yield prediction and energy value, carbohydrate profile, and in situ digestibility were evaluated for the comparison of two corn types. Our analysis for the above parameters showed that under favourable production conditions, for whole-plant corn silage, the nutritive value per unit was higher for dual-purpose corn, but biomass yield and nutritive value per ha were higher in silage-specific corn. Our current study provides data for whole-plant corn silage research and reference data for ruminant nutrition in selecting corn silage. This study was designed to evaluate the effect of hybrid type on the fermentation and nutritional parameters of whole-plant corn silage (dual-purpose and silage-specific corn). For this purpose, the two corn hybrid types were harvested at the one-half to three-fourths milk line and ensiled in fermentation bags (50 × 80 cm) for 60 day. Our results demonstrated that the ratio of lactic acid to acetic acid (p = 0.004), propionic acid (p < 0.001), Flieg point (p < 0.001), ether extract (p = 0.039), starch (p < 0.001), milk-per-ton index (p < 0.005), net energy for lactation (p = 0.003), total digestible nutrients (p < 0.001), neutral detergent soluble fiber (p =0.04), and in situ dry matter digestibility (TDMDis) (p < 0.001) were higher in dual-purpose corn silage, while the pH (p = 0.014), acetic acid (p = 0.007), the ratio of ammonia nitrogen to total nitrogen (p = 0.045), neutral detergent fiber (p < 0.001), acid detergent fiber (p < 0.001), acid detergent lignin (p < 0.001), dry matter yield per ha (p < 0.001), milk-per-acre index (p = 0.003), available neutral detergent fiber (p < 0.001), and unavailable neutral detergent fiber (p < 0.001) were higher in silage-specific corn silage. Based on our analysis, we concluded that under favourable production conditions for whole-plant corn silage, the nutritive value per unit was higher in dual-purpose corn while biomass yield and nutrient value per ha were higher in silage-specific corn. [ABSTRACT FROM AUTHOR]

Simple Summary: Silage additives, such as complex lactic acid bacteria inoculants and mixed organic acid salts, are effective at improving fermentation and preservation of corn silage. However, the effects of applying these additives at ensiling on beef cattle performance require further investigation. This study showed that corn silage, inoculated with complex lactic acid bacteria, significantly improved daily dry matter intake, ruminal ammonia nitrogen, and blood urea nitrogen; and numerically enhanced the average daily gain of growing–finishing bulls. Corn crops ensilaged with mixed organic acid salts alone or together with complex inoculants had no significant effect on animal performance, although it did alter some rumen fermentation characteristics and blood parameters. Our research contributes to the future development and selection of silage additives. This study aimed to investigate the effect of applying various silage additives to whole corn crops at ensiling on growth performance, rumen fermentation, and blood physiology in growing–finishing bulls. Sixty Simmental × Yellow Cattle crossbred bulls were blocked by initial body weight (BW; 324.0 ± 5.4 kg) into 15 blocks. Animals in each block were randomly assigned to one of four diets formulated based on the following corn silage: control (CON), inoculated with complex lactic acid bacteria (CLB), ensilaged with mixed organic acid salts (MS), and ensilaged with CLB and MS (CLBMS). The feeding experiment lasted over 155 days, with an additional 7 days for adaptation. The results showed that bulls fed CLB-inoculated silage had greater (p < 0.05) daily dry matter intake than the other groups. The experimental treatment had no significant effect on average daily gain (p = 0.33) and feed-to-gain ratio (p = 0.13), although bulls fed CLB-inoculated silage had a larger numeric average daily gain. All additive-treated silage increased ruminal NH3–N content (p < 0.05) and reduced the acetate-to-propionate ratio (p < 0.05) of bulls compared with the control group. Bulls fed CLB-inoculated silage had a lower ruminal pH value (p < 0.05) than that of the other groups. Compared with the control group, bulls fed CLB-inoculated silage had greater blood cholesterol, albumin, and urea nitrogen (p < 0.05). Blood physiological responses were similar in bulls fed MS-treated and control silage, whereas those in cattle fed CLBMS-treated silage were between bulls fed CLB- and MS-treated silages and more similar to the former. Taking animal performance and cost effectiveness into consideration, the application of CLB alone to whole corn crops at ensiling appears to be a better choice compared with the application of either MS alone or both of them together. [ABSTRACT FROM AUTHOR]

Simple Summary: Feedstuffs, such as cassava alcohol residue or potato starchy residue, have not been traditionally used as ruminant feeds for commercial production due to high fiber content and low digestibility. Steam explosion treatment can break down lignocellulosic structural components with no (or few) chemical agents, is environmentally friendly, and uses little energy, which offers great potential for large-scale application. We studied the effect of steam explosion treatment on the chemical composition, in vitro digestibility, energy value, Cornell Net Carbohydrate and Protein System (CNCPS) composition of five byproduct feedstuffs, to provide a theoretical basis for the development and utilization of the steam explosion technique to produce ruminant feedstuff. The data revealed that steam explosion treatment improved the nutritive value and in vitro dry matter digestibility of cassava alcohol residues, distillers' grains, rapeseed meal and potato starchy residue. Therefore, steam explosion treatment offers the potential to improve the suitability of these feedstuffs. Although many byproducts of milling industries have potential as a ruminant feed, they have not been widely used due to their low nutritive value, especially high-fiber content and difficult processing techniques. Steam explosion can increase the degradation of hemicellulose, cellulose and lignin and make byproduct feedstuffs more suitable as ruminant feed. Five byproduct feedstuffs: cassava alcohol residue (CAR), distillers' grains (DG), cottonseed meal (CM), rapeseed meal (RM) and potato starchy residues (PSR), were steam-exploded using five different processing parameters and the effects on the chemical composition, in vitro digestibility, energy value, and Cornell Net Carbohydrate and Protein System composition were assessed in order to provide a theoretical basis for the technique's development and utilization for ruminant feed production. In this study, after steam-explosion treatment, the nutritive value and in vitro dry matter digestibility (IVDMD) of CAR, DG, RM and PSR were improved (p < 0.05), while there was no effect on nutritive value of CM (p > 0.05). Specifically, steam explosion treatment decreased the contents of neutral detergent fiber, acid detergent fiber, available cell wall, and slowly degraded protein, and increased the total digestible nutrients, digestible energy, metabolic energy, net energy for maintenance, and net energy for gain, sugar, non-structural carbohydrate and IVDMD. Therefore, steam-explosion treatment offers the potential to improve the suitability of byproduct feedstuffs as ruminant feed. [ABSTRACT FROM AUTHOR]