Potential of guava leaves for mitigating methane emissions and modulating ruminal fermentation characteristics and nutrient degradability

Environmental impact of phytobiotic additives on greenhouse gas emission reduction, rumen fermentation manipulation, and performance in ruminants: an updated review

Ruminal fermentation is a natural process involving beneficial microorganisms that contribute to the production of valuable products and efficient nutrient conversion. However, it also leads to the emission of greenhouse gases, which have detrimental effects on the environment and animal productivity. Phytobiotic additives have emerged as a potential solution to these challenges, offering benefits in terms of rumen fermentation modulation, pollution reduction, and improved animal health and performance. This updated review aims to provide a comprehensive understanding of the specific benefits of phytobiotic additives in ruminant nutrition by summarizing existing studies. Phytobiotic additives, rich in secondary metabolites such as tannins, saponins, alkaloids, and essential oils, have demonstrated biological properties that positively influence rumen fermentation and enhance animal health and productivity. These additives contribute to environmental protection by effectively reducing nitrogen excretion and methane emissions from ruminants. Furthermore, they inhibit microbial respiration and nitrification in soil, thereby minimizing nitrous oxide emissions. In addition to their environmental impact, phytobiotic additives improve rumen manipulation, leading to increased ruminant productivity and improved quality of animal products. Their multifaceted properties, including anthelmintic, antioxidant, antimicrobial, and immunomodulatory effects, further contribute to the health and well-being of both animals and humans. The potential synergistic effects of combining phytobiotic additives with probiotics are also explored, highlighting the need for further research in this area. In conclusion, phytobiotic additives show great promise as sustainable and effective solutions for improving ruminant nutrition and addressing environmental challenges.

Review: Mechanism, effectiveness, and the prospects of medicinal plants and their bioactive compounds in lowering ruminants' enteric methane emission

Animal nutritionists continue to investigate new strategies to combat the challenge of methane emissions from ruminants. Medicinal plants (MPs) are known to be beneficial to animal health and exert functional roles in livestock due to their phytogenic compounds with antimicrobial, immunostimulatory, antioxidative, and anti-inflammatory activities. Some MP has been reported to be anti-methanogenic and can effectively lower ruminants' enteric methane emissions. This review overviews trends in MP utilization in ruminants, their bioactivity and their effectiveness in lowering enteric methane production. It highlights the MP regulatory mechanism and the gaps that must be critically addressed to improve its efficacy. MP could reduce enteric methane production by up to 8-50% by regulating the rumen fermentation pathway, directing hydrogen toward propionogenesis, and modifying rumen diversity, structure, and population of the methanogens and protozoa. Yet, factors such as palatability, extraction techniques, and economic implications must be further considered to exploit their potential fully.

Ensiling Characteristics, In Vitro Rumen Fermentation Patterns, Feed Degradability, and Methane and Ammonia Production of Berseem (Trifolium alexandrinum L.) Co-Ensiled with Artichoke Bracts (Cynara cardunculus L.)

This study investigated the effect of co-ensiling increasing levels of artichoke bracts (Cynara cardunculus L.) with berseem (Trifolium alexandrinum L.) (100:0, 75:25, 50:50, 25:75, and 0:100, respectively) on silage quality after 0, 30, 60, and 120 days. Moreover, the in vitro rumen fermentation characteristics and methane (CH₄) and ammonia (NH₃-N) production were evaluated using a buffalo inoculum source. The results showed that pH of the silage and the concentration of acetic, propionic, butyric acid, and NH₃-N significantly decreased (L; p < 0.01) with the increasing amounts of artichoke bracts in the mixture. At 30 and 60 days of ensiling, the highest lactic acid concentration was observed at intermediate proportions of artichoke bracts (p < 0.01). Cumulative gas production was higher in artichoke bracts than in the berseem silage. After 24 h of incubation, the highest value (p < 0.05) of truly dry matter, organic matter, natural detergent fiber degradability, and NH₃-N concentration was recorded with 500 g/kg of forage mixtures. As the artichoke bract concentration increased, the partitioning factor and ruminal pH declined linearly (p ≤ 0.05). No significant differences were observed for total volatile fatty acids and volatile fatty acids molar proportions. In summary, co-ensiling artichoke bracts with berseem at a ratio of 1:1 might be a promising and easy method for the production of high-quality silage from legume forage with positively manipulating rumen fermentation.

Farang (Psidium guajava L.) Dried Leaf Extracts: Phytochemical Profiles, Antioxidant, Anti-Diabetic, and Anti-Hemolytic Properties for Ruminant Health and Production

Due to its advantageous antioxidant phytochemical components, Psidium guajava L. has become an indispensable plant in pharmaceutical formulations, playing a crucial role in safeguarding human health. On ruminant animals, however, there has been limited investigation. The purpose of this investigation was to assess the phytochemical profiles and biological potential of Farang (P. guajava L.) leaf extracts for ruminant health. Methanolic and hexanoic extracts from various agricultural areas were prepared over a five-month period. By means of HPLC-DAD, vitamin C (ascorbic acid), essential oil (eugenol), tannin (gallic acid), cinnamic acids (caffeic acid, syringic acid, p-coumaric acid, sinapic acid, and ferulic acid), and flavonoids (catechin, rutin, myricetin, quercetin, apigenin, and kaempferol) were detected and quantified. Solvent type, but not cultivation site or sampling time, explained the observed variation in phytochemical profile. Phytochemicals were found in lower concentrations in hexanoic extracts than in methanolic extracts. Catechin and sinapic acid were discovered to be the two most abundant phytochemicals in the methanolic extract of Farang leaf, followed by other phenolic compounds, essential oils, and water-soluble vitamins. Compared with the methanolic extract, the hexanoic extract of Farang leaves was less effective at scavenging oxidation in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide, and superoxide, and α-glucosidase inhibitory activity. Hexanoic extract was found to be less protective against oxidative damage in ruminant erythrocytes than methanolic extract in terms of inhibiting hemoglobin oxidation, lipid peroxidation, and hemolysis. According to the findings of this study, the leaves of Farang (P. guajava L.) are a potential source of phytochemical compounds with wellness properties for ruminant production.

Potential of selected plant extracts to control severe subacute ruminal acidosis in vitro as compared with monensin

Background

In recent years, researchers have become increasingly interested in developing natural feed additives that can stabilize ruminal pH and thus prevent or eliminate the risk of severe subacute rumen acidosis. Herein, 3 experiments were conducted using a semi-automated in vitro gas production technique. In the experiment (Exp.) 1, the efficacy of 9 plant extracts (1.5 mg/ml), compared to monensin (MON; 12 μg/ml), to counteract ruminal acidosis stimulated by adding glucose (0.1 g/ml) as a fermentable carbohydrate without buffer was assessed for 6 h. In Exp. 2, cinnamon extract (CIN) and MON were evaluated to combat glucose-induced acidosis with buffer use for 24 h. In Exp. 3, the effect of CIN and MON on preventing acidosis when corn or barley grains were used as substrate was examined.

Results

In Exp. 1, cinnamon, grape seeds, orange, pomegranate peels, propolis, and guava extracts significantly increased (P < 0.05) pH compared to control (CON). Both CIN and MON significantly increased the pH (P < 0.001) but reduced cumulated gas production (P < 0.01) compared to the other treatments. In Exp. 2, the addition of CIN extract increased (P < 0.01) pH value compared to CON at the first 6 h of incubation. However, no significant differences in pH values between CIN and CON at 24 h of incubation were observed. The addition of CIN extract and MON decreased (P < 0.001) lactic acid concentration and TVFA compared to CON at 24 h. The CIN significantly (P < 0.01) increased acetate: propionate ratio while MON reduced it. In Exp. 3, both CIN and MON significantly increased (P < 0.05) ruminal pH at 6 and 24 h and reduced lactic acid concentration at 24 h compared to CON with corn as substrate. However, CIN had no effect on pH with barley substrate at all incubation times.

Conclusions

It can be concluded that CIN can be used effectively as an alternative antibiotic to MON to control ruminal acidosis when corn is used as a basal diet.

Influence of Functional Feed Supplements on the Milk Production Efficiency, Feed Utilization, Blood Metabolites, and Health of Holstein Cows during Mid-Lactation

A 70-day feeding trial was performed to assess the effect of feeding a mixture of functional feed supplements (FFS; contains encapsulated cinnamaldehyde, condensed tannins, capsaicin, piperine, and curcumin) during mid-lactation on the milk production and composition, feed intake, and blood profile of multiparous dairy cows. Sixty Holstein dairy cows (116.1 ± 17.1 days in milk, 606 ± 9.3 kg BW, and 45.73 ± 6.7 kg/d milk production) were distributed into two trial groups: control (CON: n = 30), which received a basal diet; and FFS (n = 30) treatment, which received a basal diet fortified with the FFS at a rate of 35 g/day/head. The results revealed that daily milk production (p = 0.01) and solids-not-fat yield (p = 0.05) were significantly higher in dairy cows that had received FFS compared with the control group. In addition, the 3.5% fat-corrected milk, energy-corrected milk, lactose and protein yields, and milk energy output tended to be higher (p ≤ 0.10) in dairy cattle that consumed FFS during the experimental period. Significant treatment x period interactions were identified (p ≤ 0.02) with respect to feed efficiency and somatic cell count. Dry matter intake tended to be greater (p = 0.064) in dairy cattle that consumed FFS during weeks 0–2 and 2–4 of the trial period. Most serum biochemical parameters were not changed (p ≥ 0.114) between FFS and control cows. However, a greater concentration of serum albumin (p = 0.007) was observed in cows fed diets supplemented with FFS. In summary, supplementing FFS to lactating Holstein cows during mid-lactation was associated with enhanced lactation performance, feed efficiency, and a tendency to increase feed intake, with no obvious adverse effects.

Sustainable impact of pulp and leaves of Glycyrrhiza glabra to enhance ruminal biofermentability, protozoa population, and biogas production in sheep

The aim of this study was to evaluate the effect of pulp and leaves of Glycyrrhiza glabra to reduce the ruminal biogas production in sheep. Five experimental diets of two levels of Glycyrrhiza glabra pulp (GGP) and Glycyrrhiza glabra leaves (GGL) at 150 and 300 g/kg dry matter (DM) were assessed for biogas production and fermentation parameters. Diets were control (diet without GGP or GGL), GGP15 (diet contains GGP at 150 g/kg DM), GGP30 (diet contains GGP at 300 g/kg DM), GGL15 (diet contains GGL at 150 g/kg DM), and GGL30 (diet contains GGL at 300 g/kg DM). Inclusion of 150 and 300 g/kg GGP and 300 g/kg GGL decreased (P < 0.0001) asymptotic biogas production (A), fermentation rate (μ), biogas production at 24 h of incubation (GP24), apparent degraded substrate (ADS), in vitro organic matter disappearance (OMD), and metabolizable energy (ME). Microbial protein biomass (MP) was improved (P = 0.003) by GGP15, GGL15, and GGL30 versus control. Total VFAs (P = 0.003), acetate (P = 0.009), and butyrate (P = 0.002), CH4 (mmol and mL/g OMD), CO2 (mmol and mL/g OMD) (P = 0.0003 and P = 0.0002, respectively), were decreased in GGP15, GGP30, and GGL30 diets versus control. Acetate to propionate ratio (Ac/Pr) was decreased (P = 0.038) in GGL30 diet compared to other diets. Replacing GGP and GGL with alfalfa reduced NH3-N concentration (P = 0.022), total protozoa (P < 0.0001), Isotricha spp. (P = 0.047), Dasytricha spp. (P = 0.067), subfamilies of Entodiniinae (P < 0.0001), and Diplodiniinae (P = 0.06). Results suggested that inclusion of dietary GGL at 150 g/kg dry matter positively modified some rumen parameters such as microbial protein production, protozoa population, and NH3-N concentration, which may be useful economically in ruminant animals and decreasing of environmental pollution.

Role of Secondary Plant Metabolites on Enteric Methane Mitigation in Ruminants

The rumen microbiome plays a fundamental role in all ruminant species, it is involved in health, nutrient utilization, detoxification, and methane emissions. Methane is a greenhouse gas which is eructated in large volumes by ruminants grazing extensive grasslands in the tropical regions of the world. Enteric methane is the largest contributor to the emissions of greenhouse gases originating from animal agriculture. A large variety of plants containing secondary metabolites [essential oils (terpenoids), tannins, saponins, and flavonoids] have been evaluated as cattle feedstuffs and changes in volatile fatty acid proportions and methane synthesis in the rumen have been assessed. Alterations to the rumen microbiome may lead to changes in diversity, composition, and structure of the methanogen community. Legumes containing condensed tannins such as Leucaena leucocephala have shown a good methane mitigating effect when fed at levels of up to 30–35% of ration dry matter in cattle as a result of the effect of condensed tannins on rumen bacteria and methanogens. It has been shown that saponins disrupt the membrane of rumen protozoa, thus decreasing the numbers of both protozoa and methanogenic archaea. Trials carried out with cattle housed in respiration chambers have demonstrated the enteric methane mitigation effect in cattle and sheep of tropical legumes such as Enterolobium cyclocarpum and Samanea saman which contain saponins. Essential oils are volatile constituents of terpenoid or non-terpenoid origin which impair energy metabolism of archaea and have shown reductions of up to 26% in enteric methane emissions in ruminants. There is emerging evidence showing the potential of flavonoids as methane mitigating compounds, but more work is required in vivo to confirm preliminary findings. From the information hereby presented, it is clear that plant secondary metabolites can be a rational approach to modulate the rumen microbiome and modify its function, some species of rumen microbes improve protein and fiber degradation and reduce feed energy loss as methane in ruminants fed tropical plant species.

Paulownia Leaves as A New Feed Resource: Chemical Composition and Effects on Growth, Carcasses, Digestibility, Blood Biochemistry, and Intestinal Bacterial Populations of Growing Rabbits

Simple Summary

Paulownia trees are grown as a woody biofuel crop, and they yield large amounts of leafy biomass rich in nitrogen. However, there is limited information on the use of paulownia leaves as an animal feed resource. Hence, this study was conducted to assess the effects of paulownia leaf meal (0%, 15%, and 30% in diets) on the growth performance, nutrient digestibility, blood biochemistry, and intestinal microbiota of growing rabbits. The chemical analyses of paulownia leaves indicated that most of the nutrients are similar to those in alfalfa hay. The in vivo results showed that the use of up to 15% paulownia leaf meal instead of alfalfa hay in the diets of the rabbits did not have any negative effects on their performance, nutrient digestibility, and blood constituents. In addition, a notable reduction in both cecal and feed pathogenic bacteria was observed when paulownia leaf meal was included in the diets.

Abstract

This experiment was conducted to study the effects of paulownia leaf meal (PLM) as a nontraditional feed on the growth, carcasses, digestibility, blood chemistry, and intestinal microbiota of growing rabbits. Sixty rabbits (5-weeks old) were randomly allotted to three dietary treatments containing three amounts of PLM (0%, 15%, and 30%). The results showed that PLM has a higher content of ether extract, organic matter, methionine, tyrosine, histidine, manganese, and zinc than alfalfa hay. Body weight gain decreased when 30% PLM was provided. The best feed conversion ratio was recorded in the rabbits fed 15% PLM. A notable increase in high-density lipoprotein levels with a significant decrease in low-density lipoprotein was noted in the rabbits fed the PLM diets. Total fungi and Enterobacteriaceae and total bacterial count in the feed were significantly reduced because of PLM. In the cecum, coliforms, Enterobacteriaceae species, and total bacterial count declined in the rabbits fed the PLM diets. Conclusively, up to 15% PLM can be used in rabbit diets without any deleterious effects on the performance, nutrient digestibility, and blood constituents. In addition, dietary inclusion of PLM has the potential to reduce cecal pathogenic bacteria in rabbits.