Ruminant Nutrition Research Articles

Genome-wise engineering of ruminant nutrition – nutrigenomics: applications, challenges, and future perspectives – A review

Abstract Use of genomic information in ruminant production systems can help alleviating concerns related to food security and sustainability of production. Nutritional genomics (i.e., nutrigenomics) is the field of research that is interested in all types of reciprocal interactions between nutrients and the genomes of organisms, i.e., variable patterns of gene expression and effect of genetic variations on the nutritional environment. Devising a revolutionary analytical approach to the traditional ruminant nutrition research, the relatively novel area of ruminant nutrigenomics has several studies concerning different aspects of animal production systems. This paper aims to review the current nutrigenomics research in the frame of how nutrition of ruminants can be modified accounting for individual genetic backgrounds and gene/diet relationships behind productivity, quality, efficiency, disease resistance, fertility, and greenhouse gas emissions. Furthermore, current challenges facing ruminant nutrigenomics are evaluated and future directions for the novel area are strongly argued by this review.

The Effect of Harvest Date on the Chemical Composition and Fodder Yield of Guizotia abyssinica (Guizotia abyssinica (L.f.) Cass.) under the Climatic Conditions of South-West Poland

Guizotia abyssinica (Guizotia abyssinica (L.f.) Cass.) is regarded as a minor oilseed crop, which is important in terms of its nutritional value and potential uses. An important benefit of this crop is its cultivation for green matter and seed yield even under the difficult conditions of marginal cultivation. Guizotia abyssinica has not yet gained popularity in Europe. However, in a changing climate and taking into account its feeding value, it could gain in importance for ruminant nutrition in the near future. A field experiment was conducted in 2018 and 2019 in the west part of Poland on a farm in Opolskie voivodship (commune Prudnik). The objective of the field study was to assess the effect of three harvest dates on the yield and the chemical composition of fodder in a 90-day cultivation cycle in each year of the study. Stage of growth seems to be the most important factor affecting yield and the chemical composition of Guizotia abyssinica. In both years of the research, the green fodder yield reached the highest value after 90 days from sowing—32.5 and 36.9 t ha−1—while dry matter was 6.85 and 7.99 t ha−1, respectively. Chemical composition was also significantly dependent on harvesting date. Crude protein (in 2018 from 154.5 to 100.7 g kg−1 and in 2019 from 148.3 to 78.2 g kg−1) and crude ash (in 2018 from 165.8 to 98.7 and in 2019 from 155.2 to 89.9 g kg−1) content decreased with progressive harvest date while nitrogen-free extracts (in 2018 from 500.5 to 562.0 g kg−1 and in 2019 from 582.2 to 605.2 g kg−1) and gross energy increased (in 2018 from 19.4 to 21.17 MJ kg−1 and in 2019 from 18.63 to 19.73 MJ kg−1.). The most favorable date for harvesting green forage is 90 days after sowing, due to the significantly highest yield of fresh and dry matter of green forage and with potential as a forage for animals.

PARTIAL SUBSTITUTION OF CONCENTRATE MIX WITH DRIED Leucaena leucocephala LEAF REDUCED in vitro METHANE PRODUCTION IN RAMS WITHOUT AFFECTING THE NUTRIENT INTAKE AND PERFORMANCE TRAITS

<p><strong>Background.</strong> Through <em>in vitro</em> studies, dried <em>Leucaena leucocephala<strong> </strong></em>leaf (DLL) was identified as potential candidate in mitigating enteric methane (CH<sub>4</sub>) emission. Nevertheless, its efficiency as suitable feed for sheep has not been determined in Ethiopia<strong>. Objective.</strong> To assess the suitability of replacing the concentrate mix (CM) with DLL on voluntary intake, growth performance in rams and <em>in vitro</em> CH<sub>4</sub> production. <strong>Methodology.</strong> Thirty yearling rams were first stratified according to their initial body weight similarities and then individuals from each stratum were randomly assigned to five treatment diets with six rams each. The control diet contained CM with 346 g/head/d (T1), and treatment diets replacing the CM in the control diet with DLL at a rate of 5% (T2), 10% (T3), 15% (T4) and 20% (T5) with the corresponding CM to DLL mixture ratio of 346:0, 329:17, 311:35, 294:52 and 277:69 g/head/day. Grass hay was provided <em>ad libitum</em> to all rams. Data were collected on fed intake and body weight. Methane (CH<sub>4</sub>) production was determined along with 24h <em>in vitro</em> gas production (GP). Digestible organic matter (DOM) and Metabolizable energy (ME) were estimated from 24h GP. <strong>Results. </strong>The contents of ash, crude protein (CP), neutral detergent fiber (NDFom), acid detergent fiber (ADFom) and acid detergent lignin were higher in DLL than in the control diet while it contained the lowest EE value. The DLL had the highest Ca and K values as compared to the control diet. The feed intake, live weight and weight gain did not differ (P>0.05) among rams supplemented with various levels of DLL. The total intake of CP increased across treatment diets and was significantly higher for T3, T4 and T5 than T1 and T2 diets. None of the supplementation levels of <em>L. leucocephala</em> affected the total intake of DM, NDFom and ADFom. There was a linear reduction (p<0.05) of <em>in vitro</em> CH<sub>4</sub> production as the levels of DLL in the diet were increased. It was lowest in T4 and T5 diets being significantly different from those of T1 and T2. The T5 diet showed the lowest values and differed (p<0.05) from those of T1, T2 and T3. The ME and DOM values were higher (p<0.05) in T1 and T2 diets than that of T4 and T5. No difference in ME and DOM values were observed between T1, T2 and T3 diets as well as among T4 and T5 diets. <strong>Implications.</strong> The current findings suggest that conventional CM could be replaced with DLL up to 20% as alternative protein source in ruminant nutrition in tropical and sub-tropical regions. <strong>Conclusion</strong>. The replacement of CM with DLL significantly reduced the <em>in vitro</em> CH<sub>4</sub> production across treatment diets without affecting the voluntary intake and growth performance parameters in rams.</p>

Tailored Nanoparticles With the Potential to Reduce Ruminant Methane Emissions.

Agricultural methane produced by archaea in the forestomach of ruminants is a key contributor to rising levels of greenhouse gases leading to climate change. Functionalized biological polyhydroxybutyrate (PHB) nanoparticles offer a new concept for the reduction of enteric methane emissions by inhibiting rumen methanogens. Nanoparticles were functionalized in vivo with an archaeal virus lytic enzyme, PeiR, active against a range of rumen Methanobrevibacter species. The impact of functionalized nanoparticles against rumen methanogens was demonstrated in pure cultures, in rumen batch and continuous flow rumen models yielding methane reduction of up to 15% over 11 days in the most complex system. We further present evidence of biological nanoparticle fermentation in a rumen environment. Elevated levels of short-chain fatty acids essential to ruminant nutrition were recorded, giving rise to a promising new strategy combining methane mitigation with a possible increase in animal productivity.

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.

In vitro study on the effects of exogenic fibrolytic enzymes produced from Trichoderma longibrachiatum on ruminal degradation of olive mill waste.

Olive mill waste is low-quality feed and rarely used in ruminant nutrition because of its high lignocellulose content, the existence of anti-nutritional factors such as total polyphenol and condensed tannin, and low protein contents. This in vitro research was conducted to valorize this waste (crude olive cake, extracted olive cake, and olive leaves) using an exogenous fibrolytic enzyme produced from Trichoderma longibrachiatum in ruminal nutrition. The enzymatic activity of this additive was 1161 units of endoglucanase per millilitre, 113 units of exoglucanase per millilitre, and 2267 units of xylanases per millilitre. This treatment was applied by spraying substrates with four doses: 0 (control), 1 (low), 2 (medium), and 4 (high) of dry matter olive mill waste in an air-conditioned room at 26 for 12 h before in vitro incubation.For the crude olive cake, this additive at high doses increased degradation of 14 % of cellulose and 8 % of hemicellulose compared with the control at 12 h before the in vitro incubation. Consequently, it increased dry matter solubility and reduced sugars at this period compared to the control. Upon ruminal incubation, the high dose of exogenous fibrolytic enzyme increased the gas production from the immediately soluble fraction and insoluble fraction, the rate of gas production for the insoluble fraction, the dry matter degradability by 26 %, the organic matter degradability by 24 %, the metabolizable energy value by 28 %, and the microbial crude protein production by 24 % compared with the control. For olive leaves, an exogenous fibrolytic enzyme at medium dosage can also hydrolyse the hemicellulose compound, release fewer sugars, and increase dry matter solubility compared with the control at 12 h before the in vitro incubation.Upon in vitro incubation, the medium dose increased the gas production from immediately soluble and insoluble fractions, the rate of gas production for the insoluble fraction, the dry matter degradability by 13 %, the organic matter degradability by 11 %, the metabolizable energy value by 12 %, and the microbial crude protein production by 12 % compared with the control. However, the highest dose altered the gas production from insoluble fractions and decreased microbial crude protein production by 6 % compared with the control. Under the same conditions, an exogenous fibrolytic enzyme applied to extracted olive cake did not produce any effect in the chemical composition and nutritional value. These results showed clearly that effectiveness of exogenous fibrolytic enzyme varied with incubated waste. Increasing the nutritional value of crude olive cake and olive leaves using an exogenous fibrolytic enzyme can encourage breeders to use this waste as feed at a low cost in animal nutrition. This valorization of waste is a good solution to reduce pollution of soils and groundwater caused by throwing out this polluted waste into the environment.

Treating tropical grass with fibrolytic enzymes from the fungus Trichoderma reesei: Effects on animal performance, digestibility and enteric methane emissions of growing lambs

Food security and climate change concerns are pressing livestock production industry to seek sustainable practices to increase productivity while reducing the intensity of enteric methane (CH4) emissions. In this scenario, the use of enzyme products in ruminant nutrition may be an important alternative to meet future increased demands for animal products with reduced environmental impacts. The objective of this study was to evaluate the effects of treating forage with a fibrolytic enzymes extract (FEE), produced by Trichoderma reesei, on animal performance, blood biochemical parameters, nutrient digestibility, ruminal fermentation, and enteric CH4 production of growing lambs. Nineteen Santa Inês growing lambs were divided into two groups: control (CTL) and enzyme (ENZ). The animals were fed with 700 g/kg of tifton-85 hay and 300 g/kg (as fed basis) of concentrate mixture for 73 days. The FEE was manually applied 24 h before each feed supply. Initially, animals were kept in individual pens for the growth performance trial (15 days of adaptation plus 45 for data collection), then were taken to metabolic cages (seven days) and to gas measurement chambers (six days) for the metabolism assay and determination of CH4 production, respectively. No effects (P > 0.05) were observed on dry matter intake (DMI), average daily gain (ADG), and feed conversion ratio. However, ENZ animals showed higher proportion of body weight gain (PBWG) when considering the entire growth performance period (P < 0.05). Analysis of blood parameters indicated that FEE did not impair animals’ health. Lambs fed forages treated with FEE showed 12% higher acid detergent fiber (ADF) digestibility (P < 0.05) and 20% lower enteric CH4 yield (i.e. per kg of digestible organic matter intake) (P < 0.05). Microbial protein synthesis, pH, ammonia nitrogen, short-chain fatty acids concentration and protozoa population were not affected by the addition of FEE (P > 0.05). The results indicated that FEE can be used in diets of lambs, leading to higher PBWG, improving ADF digestibility and reducing CH4 yield, suggesting its potential suitability as a strategy to increase animal productivity and contribute to the mitigation of enteric CH4 production, especially when animals are fed poor-quality forages.

Using Mid-IR spectroscopy (ATR-FTIR) as a fast analytical tool to reveal association between protein spectral profiles and metabolizable protein supply, protein rumen degradation characteristics and estimated intestinal protein digestion before and after rumen incubation of faba bean partitions and faba bean silage

To our knowledge, there is little research done in using vibrational MID-IR molecular spectroscopy- attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR) for ruminant system study. The objective of this study was to use ATR-FTIR as a fast analytical tool to reveal association between protein molecular structure in faba and metabolizable protein supply and nutrient delivery, and to explore the relationship between protein molecular structure in original and ruminal degraded residue and in situ rumen protein degradation and protein metabolism characteristics of faba bean samples (whole crop, stem, leaf, whole pods, and faba silage). The experiment for ruminant nutrition research was RCBD. Fourier transform Infrared (FTIR) spectra of faba samples before and after 12 and 24 h rumen incubations were collected with JASCO FT/IR-4200 with ATR at mid-IR range (ca. 4000–700 cm−1) with 128 scans and at 4 cm−1 resolution. The univariate molecular spectral analysis was carried using OMNIC software. Protein related spectral parameters before and after rumen degradation included amide region (ca. 1730–1480 cm−1), amide I region (ca. 1713–1558 cm−1) and amide II region (ca. 1558–1485 cm−1). Within amide I region, α-helix (ca. 1644 cm−1) and β-sheet (ca. 1630 cm−1) were studied. The results showed that ATR-FTIR protein molecular spectral features were significantly different before and after rumen incubation. Protein availability and digestion characteristic are mainly determined by original ATR-FTIR spectral profiles. Total truly digestible protein value (DVE) of faba partitions could be predicted with this equation: DVE (g/kg DM) = 1207.7 HAII12 + 228.7 alpha_beta24 − 310.8 (with R-square = 0.94, RSD = 8.06, model P < 0.001). The study shows that vibrational MID-IR molecular spectroscopy (ATR-FTIR) show a high potential to be a fast analytical tool to predict nutrient delivery.

Irish Grassland Research — main achievements and advancements in the past 60 yrs and where to progress to next

AbstractIn the last 60 yr Irish grassland production has increased substantially in no small part due to high-quality fundamental grassland research. Increased production from grassland has arisen from improved understanding (research and practice) of soil and plant nutrition, plant physiology and variety improvement, while improved understanding of feed evaluation, ruminant nutrition, grazing management and silage technology has contributed to increased utilisation of grassland. Annual grass DM production varies from 12.7 to 15.0 t DM/ha based on Department of Agriculture, Food and the Marine grass variety trials. More recent data from PastureBase Ireland indicate that average annual grass production (2020) on efficient dairy and dry stock farms is 13.5 and 10.0 t DM/ha, respectively. Ireland is now one of the world leaders in grassland research, particularly in the area of grazing utilisation, the development and use of grassland databases, decision support systems and grass selection indices for grass varieties. Future pasture-based systems must extend beyond food production to deliver additional benefits to farmers, to consumers and the wider society. Future systems will require more robust grazing animals with healthier functional traits, more diverse swards supporting improved animal performance and require fewer fertiliser and chemical inputs, and will support more biodiversity and enhanced carbon storage.

The use of near-infrared and mid-infrared spectroscopy to rapidly measure the nutrient composition and the in vitro rumen dry matter digestibility of brown seaweeds

Brown seaweeds are the most studied and exploited algae type for ruminant nutrition due to their biomass availability, ease of harvest and content of bioactive compounds. Infrared spectroscopy represents a rapid, non-invasive and chemical-free technique that is widely applied for the chemical characterization and digestible quality of many terrestrial forages. However, there is limited information regarding its application to seaweeds. This study compared the effectiveness of Near-Infrared (NIR: 9000–4000 cm-1) and Mid-Infrared (MIR: 4000–400 cm-1) spectroscopy to measure the nutritional value and in vitro dry matter rumen digestibility of brown seaweeds. Due to the small number of seaweed samples available, 40 samples were analysed in triplicate with a total dataset of 120 samples. For partial least-squares regression model development and evaluation purposes, the dataset (n = 120) was divided into two subsets, the first one for training and model development purposes (70% of data, n = 84), and the second one for model testing and evaluation (internal evaluation) purposes (30% of data, n = 36). Partial least-squares regression was employed to develop multivariate calibration models which were internally and externally validated. The samples were analysed using established wet chemistry methods which were regarded as the reference methods. NIR showed high accuracy for the quantitative prediction of crude protein (R2P = 0.99; RMSEP = 0.51; RER = 26.9; RPD = 6.9) and total polyphenolic content (R2P = 0.94; RMSEP = 0.20; RER= 10; RPD= 3.2), whereas MIR could only accurately predict crude protein (R2P = 0.96; RMSEP = 1.12; RER = 11.64; RPD = 3.14). Ash, neutral and acid detergent fiber, lignin (sa) and in vitro dry matter rumen digestibility models showed limited applicability for quantitative measurements (R2P < 0.85; RPD < 2). Overall, NIR and MIR could be used to rapidly evaluate the nutritional composition and digestibility of brown seaweeds in their dried form but further evaluation on an external database would be required to assess the robustness of these models on unrelated data. Furthermore, the use of these spectroscopic methods showed lower accuracy and precision compared to wet chemistry methods, which better qualifies them for screening rather than confirmatory analysis.

Evaluation of in vitro degradability of total mixed ration by synergistic supplementation of herbal extract-probiotic mixture in ruminants

In Kerala, crossbred cattle feeding is restricted to grazing on low-quality forages with meagre allowances of concentrates and this necessitates the supplementation of feed additives for better utilisation of low quality feed resources. The probiotic culture of Aspergillus oryzae is widely used in ruminant nutrition because of its buffering function in stabilizing the rumen environment and stimulation of microbial activity especially fibrolytic activity. Psidium guajava leaves are antimethanogenic in action and the biological activities of these leaves include improving rumen fermentation and nutrient utilization in livestock. Hence a preliminary screening of the synergistic supplementation of different levels of A. oryzae and P. guajava leaf extracts at 0, 0.5, 0.25, and 0.125 per cent respectively in the total mixed ration (TMR) of concentrate: roughage (60:40) on dry matter(DM) basis was studied using in vitro gas production technique (IVGPT) with a view to estimate the metabolisable energy, digestible organic matter, methane production and in vitro degradable nitrogen(IVDN). The percentage of IVDN was significantly (p&lt;0.01) higher for the treatment group supplemented with the herbal extract-probiotic mixture at 0.25% level. The percentage of methane production was significantly (p&lt;0.01) lower for the treatment groups supplemented with the herbal extract-probiotic mixture at 0.5% and 0.25% with values of 8.42% and 10.8% respectively. The results indicated that synergistic supplementation of P. guajava leaf extract and A. oryzae probiotic culture each at 0.25% level in the TMR gave the best performance in terms of methane mitigation and optimum availability of IVDN for improved growth performance in crossbred dairy calves.

Impact of improved agricultural extension approaches on technology adoption: Evidence from a randomised controlled trial in rural Tunisia

Summary Low and slow adoption of innovative technologies among smallholder farmers in Tunisia is a key agricultural development problem partly related to the existing technology transfer approach used in the country. The objective of this study is to analyse how to design innovative technology transfer strategies more effective in terms of increasing female and male farmers’ adoption of an improved barley variety, ‘Kounouz’, for small ruminant nutrition. A randomised controlled trial method was used with farmers in Tunisia to implement four extension treatments and to evaluate their effects on adoption of Kounouz. Difference-in-difference estimates showed that intensive agricultural trainings can significantly improve adoption of Kounouz. Technical trainings combined with economic and organisational training and female empowerment courses resulted in a higher adoption rate. This finding has important policy implications, because it suggests that ensuring more widespread and equitable adoption of improved technologies may not require changes in the research system, but rather introduction measures that ensure better access for women to gender-sensitive extension programmes given their positive impacts on technology adoption of the household.

Optimization of the Fermentation Conditions for Brewing Yeast Biomass Production Using the Response Surface Methodology and Taguchi Technique

Yeast (including brewing yeast) and yeast-based preparations derived from bioprocesses or agroindustrial byproducts represent valuable feed additives and ingredients for ruminants. The optimization of brewing yeast biotechnological processing through fermentation mediated by the brewing yeast strain Saccharomyces pastorianus ssp. carlsbergensis W34/70 was investigated. The cultivation conditions (temperature, pH, carbon source, and nitrogen source) were selected and designed according to a Taguchi fractional experimental plan, with four factors on three levels, and their influence on the evolution of the bioprocess of obtaining the brewing yeast biomass was evaluated. The dependent variables were the yeast biomass amount in wet form, yeast biomass amount in dried form after lyophilization, dried yeast biomass wettability assayed through the contact angle (CA), protein content (PC), and dry matter content (DS). The effects that the experimental conditions had on the system responses were visualized in tridimensional space using the response surface methodology, and the combination of biotechnological parameters that ensured process quality and robustness was then determined using the Taguchi technique through its performance indicator, i.e., the signal-to-noise ratio. By optimizing the biotechnological parameters, this study provides a valuable contribution in the area of brewing yeast biomass processing, with the aim of producing probiotic yeast for ruminant nutrition.

Using attenuated-total-reflection Fourier-transformed spectroscopy to reveal molecular structural differences among willow (Salix spp.) foliage cultivars in relation to their potential as fodders.

Willow trees represent a suitable species for the development of agroforestry systems, integrating bioenergy and animal feed production. However, there is a lack of information regarding the suitability of leaves and stems, considered a bioenergy by-product, as animal feed. The aim of this study was the employment of attenuated total reflectance Fourier transform infrared spectroscopy (550-4000 cm-1 ) to investigate differences in the nutrient molecular structure profile of leaves and stems of selected willow cultivars to understand their utility for ruminant nutrition. Univariate analysis of variance of leaves showed lower intensities of cellulosic compounds and higher of protein in comparison with stems, which suggests higher leaf dry matter and protein digestibility. Spectral analyses revealed differences in both plant parts between Salix cv. Terra Nova and Salix cv. Beagle, cv. Resolution, and cv. Olof. The higher α-helix to β-sheet ratio, which is related to a higher protein digestibility, was in correlation with the lower content of condensed tannins. Principal component and agglomerative hierarchical cluster analyses showed significant discrimination among willow cultivars in the cellulosic, structural carbohydrate, and amide regions, whereas differences were less evident for total carbohydrate and lipid-related regions. The application of attenuated total reflectance Fourier transform infrared molecular spectroscopy is an effective tool to rapidly identify spectral features related to the nutritional composition of willow foliage and to discriminate between cultivars and parts of the plant. This information would be useful to optimize the use of willow fodders in agroforestry systems. © 2021 Society of Chemical Industry.

Influence of microbial probiotics on ruminant health and nutrition: sources, mode of action and implications

Globally, ruminant production contributes immensely to the supply of the highest quality and quantity of proteins for human consumption, sustenance of livelihoods, and attainment of food security. Nevertheless, the phasing out of antibiotics in animal production has posed a myriad of challenges, including poor growth, performance and nutrient utilization, pathogen colonization, dysbiosis, and food safety issues in ruminants. Probiotics (direct-fed microbials), comprising live microbial strains that confer health and nutritional benefits to the host when administered in appropriate quantities, are emerging as a viable, safe, natural and sustainable alternative to antibiotics. Although the mechanisms of action exerted by probiotics on ruminants are not well elucidated, dietary probiotic dosage to ruminants enhances development and maturation, growth and performance, milk production and composition, nutrient digestibility, feed efficiency, pathogen reduction, and mitigation of gastrointestinal diseases. However, the beneficial response to probiotic supplementation in ruminants is not consistent, being dependent on the microbial strain selected, combination of strains, dose, time and frequency of supplementation, diet, animal breed, physiological stage, husbandry practice, and farm management. Nonetheless, several studies have recently reported beneficial effects of probiotics on ruminant performance, health and production. This review conclusively re-iterates the need for probiotics inclusion for the sustainability of ruminant production. Considering the role that ruminants play in food production and employment, global acceptance of sustainable ruminant production through supplementation with probiotics will undoubtedly ensure food security and food safety for the world. © 2021 Society of Chemical Industry.

L-Arginine Nutrition and Metabolism in Ruminants.

L-Arginine (Arg) plays a central role in the nitrogen metabolism (e.g., syntheses of protein, nitric oxide, polyamines, and creatine), blood flow, nutrient utilization, and health of ruminants. This amino acid is produced by ruminal bacteria and is also synthesized from L-glutamine, L-glutamate, and L-proline via the formation of L-citrulline (Cit) in the enterocytes of young and adult ruminants. In pre-weaning ruminants, most of the Cit formed de novo by the enterocytes is used locally for Arg production.In post-weaning ruminants, the small intestine-derived Cit is converted into Arg primarily in the kidneys and, to a lesser extent, in endothelial cells, macrophages, and other cell types. Under normal feeding conditions, Arg synthesis contributes 65% and 68% of total Arg requirements for nonpregnant and late pregnany ewes fed a diet with ~12% crude protein, respectively, whereas creatine production requires 40% and 36% of Arg utilized by nonpregnant and late pregnant ewes, respectively. Arg has not traditionally been considered a limiting nutrient in diets for post-weaning, gestating, or lactating ruminants because it has been assumed that these animals can synthesize sufficient Arg to meet their nutritional and physiological needs. This lack of a full understanding of Arg nutrition and metabolism has contributed to suboptimal efficiencies for milk production, reproductive performance, and growth in ruminants. There is now considerable evidence that dietary supplementation with rumen-protected Arg (e.g., 0.25-0.5% of dietary dry matter) can improve all these production indices without adverse effectson metabolism or health. Because extracellular Cit is not degraded by microbes in the rumen due to the lack of uptake, Cit can be used without any encapsulation as an effective dietary source for the synthesis of Arg in ruminants, including dairy and beef cows, as well as sheep and goats. Thus, an adequate amount of supplemental rumen-protected Arg or unencapsulated Cit is necessary to support maximum survival, growth, lactation, reproductive performance, and feed efficiency, as well as optimum health and well-being in all ruminants.

The Utilisation of Tannin Extract as a Dietary Additive in Ruminant Nutrition: A Meta-Analysis.

Simple SummaryTannin has been extensively assessed for its potential and utilisation as a ruminant feed additive in recent years and is becoming important due to its beneficial effects on modulating ruminant performance and health and mitigating methane emissions. However, evidence concerning the effect of tannin in extracted forms on ruminants appears to be inconclusive on whether it can genuinely provide either beneficial or detrimental effects for ruminants. Moreover, the effects of various sources, types of tannin extract, or appropriate levels of supplementation on ruminants remain unclear. Therefore, there is a need for a systematic evaluation concerning the effects of tannin extract on rumen fermentation, digestibility, performance, methane emissions, and metabolism of ruminants.The objective of this meta-analysis was to elucidate whether there are general underlying effects of dietary tannin extract supplementation on rumen fermentation, digestibility, methane production, performance, as well as N utilisation in ruminants. A total of 70 papers comprised of 348 dietary treatments (from both in vivo and in situ studies) were included in the study. The database was then statistically analysed by the mixed model methodology, in which different experiments were considered as random effects and tannin-related factors were treated as fixed effects. The results revealed that an increased level of tannin extract inclusion in the diet lowered ruminant intake, digestibility, and production performance. Furthermore, the evidence also showed that an increased level of tannin extract decreased animal N utilisation where most of rumen by-pass protein was not absorbed well in the small intestine and directly excreted in the faeces. Due to the type of tannin extract, HT is more favourable to maintain nutrient intake, digestibility, and production performance and to mitigate methane production instead of CT, particularly when supplemented at low (<1%) to moderate (~3%) levels.

Bioavailability of Dietary Zinc Sources and Their Effect on Mineral and Antioxidant Status in Lambs

This study investigated the relative bioavailability (RBV) of zinc from different sources used as feed additives in ruminant nutrition based on Zn concentration and the activity of Zn-dependent enzymes in lamb tissues. Thirty-two male lambs of Improved Valachian breed (three months old) were randomly assigned to four dietary treatments. For 120 days, the lambs were fed either the total mix ration (TMR) providing 29.6 mg Zn/kg or the TMR supplemented with either zinc sulphate (ZnSO4), zinc chelate of glycine hydrate (ZnGly), or zinc chelate of protein hydrolysate (ZnProt). The supplemented diets contained a total of 80 mg Zn/kg. Supplementation with ZnSO4 increased Zn concentration in the liver, while the highest Zn uptake was in the kidneys of lambs fed the ZnProt diet. The ZnGly supplemented diet elevated the activity of the Cu/Zn-dependent enzyme superoxide dismutase (Cu/Zn SOD) in the liver. Regardless of Zn source, Zn supplementation resulted in increased total antioxidant status (TAS) in the pancreas. The estimated RBV of Zn based on linear regression slope ratios did not differ among the Zn sources. Our results indicate similar availability of Zn from organic dietary sources as from commonly used zinc sulphate; however, their effects on mineral and antioxidant status may differ slightly in growing lambs.

In vitro ruminal fermentation, methane production and nutrient degradability as affected by fruit and vegetable pomaces in differing concentrations.

Pomaces are food industry by-products and may serve as animal feed to increase sustainability of meat and milk production. The aim of the present study was to evaluate fermentation characteristics of dried fruit and vegetable pomaces in a short-term in vitro experiment using the Hohenheim Gas Test. A selection of six fruit (apple, aronia, orange, pomegranate, red, white grape) and three vegetable (beetroot, carrot, tomato) pomaces was tested in three concentrations (150, 300, 500gkg-1 of dry matter (DM)) as supplement to the basal diet (hay, used as control). Three runs were performed, using rumen fluid from one of three different rumen-cannulated cows in each run. Per run, each compound was tested in duplicate. After 24h incubation, total gas production, methane and CO2 concentration, short-chain fatty acids, in vitro organic matter digestibility as well as microbial counts were determined. In addition, the pomaces' polyphenol content including the fractions non-tannin phenols, condensed tannins and hydrolysable tannins were analysed. Most pomaces did not significantly affect rumen fermentation characteristics in any of the tested dosages and may thus be applied in ruminant nutrition without adverse effects. Aronia significantly decreased (-14.5%) the organic matter digestibility in the highest concentration whereas apple (+12%), carrot (+10%) and beetroot (+8%) increased gas formation related to digestible organic matter. The 500gkg-1 dosage of pomegranate significantly decreased methane formation by about 28% without impairing digestibility. Pomegranate was the only pomace of those high in total tannins that contained exceptionally high amounts of hydrolysable (90% of total tannins) and proportionally low amounts of condensed tannins (10% of total tannins), indicating that the hydrolysable tannins most likely reduced the methane production. Therefore, pomegranate pomace may be an interesting option for a methane mitigating feed supplement in ruminants and should be considered for following in vivo testing.

Proper motility enhances rumen fermentation and microbial protein synthesis with decreased saturation of dissolved gases in rumen simulation technique

The physiological function of the reticulorumen plays an essential role in ruminant nutrition, and detailed knowledge of rumen motility can further advance understanding of ruminant nutrition and physiology. Rumen motility was simulated by setting different stirrer rotation speeds in a rumen simulation technique (RUSITEC) system. The aim of this study was to investigate the effects of rotation speeds on rumen fermentation, saturation factor of dissolved gases, hydrogen (H2) and methane (CH4) emissions, microbial protein synthesis, and selected microbial population using RUSITEC. The experiment was performed according to a balanced 3 × 3 Latin square design, and each period included 7 d for adaptation and 3 d for sampling. Three motility treatments included 5, 15, and 25 rpm rotation speeds. Daily total gas and H2 and CH4 emissions had quadratic responses to the increasing rotation speed and were highest at 15 rpm. Quadratic and linear responses (highest at 5 rpm) to increasing rotation speed were observed for saturation factors of H2 and CH4, liquid-dissolved H2 and CH4 concentrations, and headspace concentration of H2 in the gas phase, whereas increasing rotation speed linearly decreased saturation factors of CO2 and liquid-dissolved CO2 concentration. Quadratic and linear responses to increasing rotation speed were observed for molar percentages of acetate, ammonia, and microbial protein concentration, whereas increasing rotation speed quadratically increased pH and decreased total volatile fatty acid concentration and acetate-to-propionate ratio. The 15-rpm rotation speed had the highest values of total volatile fatty acids, acetate molar percentage, and microbial protein concentration. Quadratic and linear responses to increasing rotation speed were observed for copy numbers of solid-associated fungi and fluid-associated bacteria, fungi, and protozoa, while increasing rotation speed linearly increased copy numbers of solid-associated protozoa. Rotation at 15 rpm increased populations of fungi and protozoa in the solid rumen contents and the population of bacteria and fungi in the liquid rumen contents. In summary, this study provides insights on the biofunction of proper rumen motility (i.e., at a rotation speed of 15 rpm), such as improving feed fermentation, increasing gas emissions with decreased dissolved gas concentrations and saturation factors, and promoting microbial colonization and microbial protein synthesis, although further increase in rotation speed (i.e., to 25 rpm) decreases feed fermentation and microbial protein synthesis.