Effects of dry yeast supplementation on growth performance, rumen fermentation characteristics, slaughter performance and microbial communities in beef cattle

Isoacids supplementation improves growth performance and feed fiber digestibility associated with ruminal bacterial community in yaks

Introduction

This study was conducted to assess the effect of mixed isoacid (MI) supplementation on fermentation characteristics, nutrient apparent digestibility, growth performance, and rumen bacterial community in yaks.

Methods

A 72-h in vitro fermentation experiment was performed on an ANKOM RF gas production system. MI was added to five treatments at doses of 0, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% on the dry matter (DM) basis of substrates using a total of 26 bottles (4 bottles per treatment and 2 bottles as the blank). Cumulative gas production was measured at 4, 8, 16, 24, 36, 48, and 72 h. Fermentation characteristics including pH, the concentration of volatile fatty acids (VFAs), ammonia nitrogen (NH₃-N), microbial proteins (MCP), and the disappearance rate of dry matter (DMD), neutral detergent fiber (NDFD), and acid detergent fiber (ADFD) were measured after a 72-h in vitro fermentation to determine an optimal MI dose. Fourteen Maiwa male yaks (180-220 kg, 3-4 years old of age) were randomly assigned to the control group (without MI, n = 7) and the supplemented MI group (n = 7, supplemented with 0.3% MI on DM basis) for the 85-d animal experiment. Growth performance, nutrient apparent digestibility, rumen fermentation parameters, and rumen bacterial diversity were measured.

Results

Supplementation with 0.3% MI achieved the greatest propionate and butyrate content, NDFD and ADFD compared with other groups (P < 0.05). Therefore, 0.3% was used for the animal experiment. Supplementation with 0.3% MI significantly increased the apparent digestibility of NDF and ADF (P < 0.05), and the average daily weight gain of yaks (P < 0.05) without affecting the ruminal concentration of NH₃-N, MCP, and VFAs. 0.3% MI induced rumen bacteria to form significantly different communities when compared to the control group (P < 0.05). g__norank_f__Bacteroidales_BS11_gut_group, g__norank_f__Muribaculaceae, g__Veillonellaceae_UCG-001, g__Ruminococcus_gauvreauii_group, g__norank_f__norank_o__RF39 and g__Flexilinea were identified as the biomarker taxa in responding to supplementation with 0.3% MI. Meanwhile, the abundance of g__Flexilinea and g__norank_f__norank_o__RF39 were significantly positively correlated with the NDF digestibility (P < 0.05).

Conclusion

In conclusion, supplementation with 0.3% MI improved the in vitro rumen fermentation characteristics, feed fiber digestibility, and growth performance in yaks, which was associated with changes of the abundance of g__Flexilinea and g__norank_f__norank_o__RF39.

Effects of a novel direct-fed microbial on growth performance, carcass characteristics, nutrient digestibility, and ruminal morphology of beef feedlot steers

The effects of a novel direct-fed microbial (DFM) on feedlot performance, carcass characteristics, digestibility, ruminal morphology, and volatile fatty acid (VFA) profile of finishing steers were evaluated. Single-source Angus-crossbred yearling steers (n = 144; initial body weight (BW) = 371 ± 19 kg) were used in a randomized complete block design. Steers were blocked by initial BW and randomly assigned to treatments (12 pens/treatment; 4 steers/pen). Treatments included (A) CONTROL (no DFM, tylosin, or monensin, (B) MONTY (monensin sodium [330 mg/animal-daily] and tylosin phosphate [90 mg/animal-daily]), and (C) MONPRO (monensin sodium [same as previous] and Lactobacillus salivarius L28 [1 × 106 CFU/animal-daily]). Treatments were included in a steam-flaked corn-based finisher diet offered once daily using a clean-bunk management for ~149 d. The digestibility assessment was performed from days 70 to 74. Ruminal fluid and rumen tissue samples were collected at the slaughter for VFA profile and papillae morphology analyses, respectively. Data were analyzed using the GLIMMIX procedure of SAS with pen serving as the experimental unit, treatment as fixed effect, and BW block as random effect. Steers offered MONPRO had on average 5.3% less (P < 0.01) dry matter intake (9.56 kg/d) compared with either CONTROL (10.16 kg/d) or MONTY (9.96 kg/d). The carcass-adjusted final BW (613 kg; P = 0.23), overall average daily gain (1.64 kg/d; P = 0.23), and gain-efficiency (0.165; P = 0.61) were not affected by treatments. Steers offered CONTROL had greater (P < 0.01) marbling score and tended (P = 0.06) to have less carcasses grading Select and tended (P = 0.10) to have more carcasses grading Upper-Choice, while other carcass characteristics and liver-abscesses were not affected (P ≥ 0.23) by treatments. The digestibility of nutrients (P ≥ 0.13) and the ruminal VFA profile (P ≥ 0.12) were not affected by treatments. Steers offered MONPRO tended (P = 0.09) to have 16% greater average papillae number compared to other treatments. Yearlings offered finishing diets containing L. salivarius L28 plus monensin did not affect growth performance, digestibility, or ruminal VFA, but reduced feed intake. Carcass quality was negatively affected by treatments, while animals consuming L. salivarius L28 and monensin tended to improve ruminal morphology. Current findings in ruminal morphology and feed intake may warrant further assessment of diets containing L. salivarius L28 on beef cattle food safety aspects.

Alterations in the rumen bacterial communities and metabolites of finishing bulls fed high-concentrate diets supplemented with active dry yeast and yeast culture

This study investigated the effects of active dry yeast (ADY) and yeast culture (YC) supplementation on rumen bacteria and metabolites in finishing bulls fed high-concentrate diets using the full-length 16S rDNA gene sequencing and liquid chromatography-mass spectrometry. Supplementation with ADY improved the alpha diversity and relative abundance of rumen bacteria, while YC only affected relative abundance of rumen bacteria at the genus level. Sixty-three differential metabolites were identified in rumen fluid after ADY supplementation, and 17 after YC. PICRUSt2 functional prediction showed that ADY supplementation improved the capacity of amino acid metabolism, lipid metabolism, carbohydrate metabolism, metabolism of terpenoids and polyketides, and energy metabolism in rumen bacteria (all P < 0.05). Correlation analysis showed that the rumen differential metabolites following ADY supplementation were mainly related to Oligosphaera, Verruc, Mycoplasma, and Anaeroplasma. Supplementation with ADY was more effective than YC in remodeling the rumen bacterial flora structure and metabolite composition under high-concentrate diets.

Role of probiotics in ruminant nutrition as natural modulators of health and productivity of animals in tropical countries: an overview

Given the ever-growing population in the developing countries located in the tropics of Asia, Africa, South America, and the Caribbean, the demand for products of animal origin has increased. Probiotics have proven to be a substantial substitute for antibiotics used in the animal diet and thus gained popularity. Probiotics are live and non-pathogenic microbes commercially utilized as modulators of gut microflora, hence exerting advantageous effects on the health and productivity of animals in tropical countries. Probiotics are mainly derived from a few bacterial (Lactobacillus, Enterococcus, Streptococcus, Propionibacterium, and Prevotella bryantii) and yeast (Saccharomyces and Aspergillus) species. Numerous studies in tropical animals revealed that probiotic supplementation in a ruminant diet improves the growth of beneficial rumen microbes, thus enhancing nutrient intake and digestibility, milk production, and reproductive and feed efficiency, along with immunomodulation. Furthermore, probiotic applications have proven to minimize adverse environmental consequences, including reduced methane emissions from ruminants' anaerobic fermentation of tropical feedstuffs. However, obtained results were inconsistent due to sources of probiotics, probiotic stability during storage and feeding, dose, feeding frequency, and animal factors including age, health, and nutritional status of the host. Furthermore, the mechanism of action of probiotics by which they exhibit beneficial effects is still not clear. Thus, more definitive research is needed to select the most effective strains of probiotics and their cost-benefit analysis. In this review article, we have briefly explained the impact of feeding probiotics on nutrient intake, digestibility, reproduction, growth efficiency, productivity, and health status of tropical ruminant animals.

Implication and challenges of direct-fed microbial supplementation to improve ruminant production and health

Direct-fed microbials (DFMs) are feed additives containing live naturally existing microbes that can benefit animals' health and production performance. Due to the banned or strictly limited prophylactic and growth promoting usage of antibiotics, DFMs have been considered as one of antimicrobial alternatives in livestock industry. Microorganisms used as DFMs for ruminants usually consist of bacteria including lactic acid producing bacteria, lactic acid utilizing bacteria and other bacterial groups, and fungi containing Saccharomyces and Aspergillus. To date, the available DFMs for ruminants have been largely based on their effects on improving the feed efficiency and ruminant productivity through enhancing the rumen function such as stabilizing ruminal pH, promoting ruminal fermentation and feed digestion. Recent research has shown emerging evidence that the DFMs may improve performance and health in young ruminants, however, these positive outcomes were not consistent among studies and the modes of action have not been clearly defined. This review summarizes the DFM studies conducted in ruminants in the last decade, aiming to provide the new knowledge on DFM supplementation strategies for various ruminant production stages, and to identify what are the potential barriers and challenges for current ruminant industry to adopt the DFMs. Overall literature research indicates that DFMs have the potential to mitigate ruminal acidosis, improve immune response and gut health, increase productivity (growth and milk production), and reduce methane emissions or fecal shedding of pathogens. More research is needed to explore the mode of action of specific DFMs in the gut of ruminants, and the optimal supplementation strategies to promote the development and efficiency of DFM products for ruminants.