Influence of Oleic Acid on Rumen Fermentation and Fatty Acid Formation In Vitro

Integrating 16S rRNA Sequencing and LC-MS-Based Metabolomics to Evaluate the Effects of Dietary Crude Protein on Ruminal Morphology, Fermentation Parameter and Digestive Enzyme Activity in Tibetan Sheep

The dietary crude protein level could affect ruminal fermentation parameters and the microflora of ruminants. The present study's aim was to investigate the effects of different protein level diets on ruminal morphology, fermentation parameters, digestive enzyme activity, microflora and metabolites of Tibetan sheep. Ninety weaned lambs (initial weight of 15.40 ± 0.81 kg, 2 months old) were selected and randomly divided into three groups (six pens/treatment, five rams/pen). Dietary treatments were formulated with 13.03% (high protein, HP), 11.58% (moderate protein, MP) and 10.20% (low protein, LP), respectively. Compared with LP, both papillae length and papillae width were significantly promoted in HP and MP (p < 0.05). The concentrations of ammonia nitrogen, total VFAs, propionic acids and butyric acids in HP were significantly increased compared to those in MP and LP (p < 0.05). The activities of protease and α-amylase in HP were significantly greater than those of LP (p < 0.05). For the ruminal microbial community, higher proportions of phylum Prevotella 1 and Succiniclasticum and genus Rikenellaceae RC9 gut group and Ruminococcus 1 were observed in HP (p < 0.05). A total of 60 differential metabolites (DMs) (28 up, 32 down) between HP and MP; 73 DMs (55 up, 18 down) between HP and LP; and 65 DMs (49 up, 16 down) between MP and LP were identified. Furthermore, four pathways of the biosynthesis of unsaturated fatty acids, tryptophan metabolism, bile secretion and ABC transporters were significantly different (p < 0.05). The abundance of phylum Prevotella 1 was negatively associated with stearic acid and palmitic acid but positively associated with the taurine. The abundance of genus Ruminococcus 1 was negatively associated with stearic acid, oleic acid, erucic acid, Indole-3-acetamide and palmitic acid but positively associated with 6-hydroxymelatonin. In conclusion, a 13.03% CP level improved ruminal morphology, fermentation parameters and digestive enzyme activities through modulating the microbial community and regulating metabolism in Tibetan sheep.

Methane emission, intake, digestibility, performance and blood metabolites in sheep supplemented with cupuassu and tucuma cake in the eastern Amazon

The use of co-products as a feed supplement for ruminants makes livestock sustainable and optimizes the use of available areas and animal performance. Furthermore, when cakes are used, the residual fat composition can influence ruminal metabolism and methane (CH4) production. This study aimed to assess the effects of a diet containing cupuassu (CUP; Theobroma grandiflorum) and tucuma (TUC; Astrocaryum vulgare Mart.) cakes on intake, digestibility, serum metabolites, performance, and CH4 emissions in confined sheep in the Amazon. Approximately 28 animals, Dorper-Santa Inês, castrated, with an average initial live weight (ILW) of 35 ± 2.3 kg, were distributed in metabolic cages, in a completely randomized design, with four treatments and seven replications: (1) Control (C40), without the addition of Amazonian cake and with 40 g of ether extract (EE)/kg of dietary dry matter (DM); (2) CUP, the inclusion of the CUP cake and 70 g of EE/kg; (3) TUC, the inclusion of the TUC cake and 70 g of EE/kg; and (4) Control (C80), without the addition of Amazonian cake and with 80 g of EE/kg of dietary DM, with roughage to concentrate ratio of 40:60. The use of the TUC cake as a feed supplement reduced the intake of DM, crude protein (CP), and EE compared to the inclusion of the CUP cake (p < 0.05); however, it increased the intake of neutral detergent fiber (NDF) by 32% (p < 0.01). The highest averages of DM (732 g/kg) and CP (743 g/kg) digestibility were presented in C40, while the highest digestibility of NDF was presented in TUC (590 g/kg). Albumin levels stayed above and protein levels were below the reference values, and the C40 diet also obtained below results for cholesterol, triglycerides and High Density Lipoprotein (HDL) (P < 0.05). Sheep fed CUP (91 g) and TUC (45 g) had lower daily weight gains (DWGs) than those fed with diets without the inclusion of cakes (C40 = 119 g; C80 = 148 g), and feed efficiency (FE) was also lower in CUP (84) and TUC (60) diets than in C40 (119) and C80 (137) diets. CH4 emissions were lower in animals fed TUC (26 L/day) and higher in C40 (35 L/day); however, TUC resulted in higher CH4 emissions in grams/body live weight (BW) gain/day (353 g/BW/day) vs. 183 g/BW/day (C40), 157 g/BW/day (C80), and 221 g/BW/day (CUP). The supplementation with cakes did not improve intake, digestibility and performance, did not compromise blood metabolites and did not reduce the enteric CH4 emission in confined sheep in the Amazon; however, the use of CUP cake showed similar results to the control treatments and did not increase CH4 emissions, as occurred with the inclusion of TUC cake.

Litter size influences rumen microbiota and fermentation efficiency, thus determining host early growth in goats

Introduction

Multiple litters are accompanied by low birth weight, low survival rates, and growth rates in goats during early life. Regulating rumen microbiota structure can indirectly or directly affect host metabolism and animal growth. However, the relationship between high litter size and rumen microbiome, rumen fermentation, and growth performance in goat kids is unclear.

Methods

In the present study, thirty 6-month-old, female goats were investigated, of which 10 goats were randomly chosen from single, twin and triplet goats respectively, and their birth weight was recorded. From birth, all goats were subjected to the same feed and management practices. Individual weaning and youth body weight were measured, and the rumen fluid samples were collected to characterize the bacterial communities and to determine the ruminal volatile fatty acids (VFA), free amino acids (AA), and free fatty acids (FA) concentration of those young goats.

Results and Discussion

Compared with the single and twin goats, triplet goats have lower weaning and youth body weight and average daily gain (ADG). Ruminal propionate, butyrate, and total VFA were decreased in triplet goats. Meanwhile, ruminal AA, such as branched chain amino acids (BCAA), essential amino acids (EAA), unsaturated fatty acids (UFA), and monounsaturated fatty acids (MUFA) were decreased, while saturated fatty acids (SFA) and odd and branched chain fatty acids (OBCFA) were increased in triplet goats. Our results also revealed that litter size significantly affected the rumen bacterial communities, and triplet goats had a lower the Firmicutes: Bacteroidota ratio, the abundance of Firmicutes phylum, Rikenellaceae family, and Rikenellaceae RC9 gut group, and had a higher proportion of Prevotellaceae family, and several genera of Prevotellaceae, such as Prevotella, and unclassified f Prevotellaceae. Furthermore, Spearman's correlation network analysis showed that the changes in the rumen bacteria were associated with changes in rumen metabolites. In conclusion, this study revealed that high litter size could bring disturbances to the microbial communities and decrease the rumen fermentation efficiency and growth performance, which can be utilized to better understand variation in microbial ecology that will improve growth performance in triplet goats.

In vitro rumen fermentation pattern: insights from concentrate level and plant oil supplement

The addition of oil to ruminant diets and oil fatty acid profiles are major factors that negatively affect ruminal fermentation, while increased forage level attenuates the adverse effects. The aim of this study was to determine the effects of oil source supplementation and concentrate level in the diet on in vitro ruminal fermentation kinetics. Pomegranate, garlic or sunflower oils were added (2 % dry matter (DM) basis) to the diets containing 40 % or 60 % (DM basis) concentrates. In vitro gas production parameters, pH, ammonia nitrogen concentration and total protozoa count were measured. Additionally, metabolizable energy (ME), short-chain fatty acid (SCFA) production and organic matter digestibility (OMD) were determined. Rumen fermentation parameters and protozoal population counts were analyzed as a completely randomized design with a 2  ×  3 factorial arrangement of treatments, and gas production parameters were analyzed as a 2  ×  3 factorial arrangement in a randomized block design. The results showed that the HCPO (high (60 %) concentrate diet containing pomegranate oil) and HCSO (high (60 %) concentrate diet containing sunflower oil) diets produced the highest (5.40 mg dL - 1 ) and lowest (2.61 mg dL - 1 ) concentrations of NH 3 -N ( p > 0.01 ), respectively. Total protozoa count tended ( p = 0.07 ) to be highest in HCPO and lowest in HCSO diets (5.10 vs. 4.81 Log 10 g - 1 digesta). No interaction effects between the concentrate level and oil source were found on in vitro gas production parameters, pH, estimated ME, SCFA and OMD, and Entodinium and Diplodinium populations ( p > 0.05 ). It is concluded that dietary supplementation with highly unsaturated oil from three different sources at 2 % level (DM basis) had no apparent effects on in vitro ruminal fermentation patterns.

Effect of canola oil supplementation level on total tract digestion, ruminal fermentation, and methane emissions of cows grazing Urochloa sp. supplemented with a fixed amount of concentrate

Four rumen-cannulated cows (Bos taurus × Bos indicus, 657 ± 92 kg body weight, BW) in a rotational grazing (Urochloa sp.) system were assigned to different canola oil (CO) inclusion levels, 0.0, 0.40, 0.80, and 1.2 g/kg according to shrunk body weight (SBW, BW adjusted for gastrointestinal filling) in a 4 × 4 Latin Square design to evaluate CO on the CH₄ emissions and dietary energy intake. CH₄ emissions were estimated using an infrared analyzer methodology (Sniffer method). Grass intake and fecal production were estimated using Cr₂O₃ as an external marker. CO supplementation increased (linear effect, P ≤ 0.05) total dry matter and gross energy intake with a linear increase (P = 0.09) in neutral detergent fiber (NDF) intake. While digestible energy (Mcal/kg) linearly increased with increasing CO supplementation level (linear effect, P < 0.05), total tract digestion of organic matter, NDF, and CP was comparable (P > 0.05) between levels. Maximal CO supplementation (1.2 g/kg SBW) significantly decreased total ruminal protozoa population, acetate:propionate ratio, and enteric methane production (g/kg DMI) by 9, 5.3, and 17.5%, respectively. This study showed that, for cows grazing tropical forages, CO can be supplemented up to 1.2 g/kg SBW (5.8% of the total diet) without negatively affecting intake and nutrient digestion while reducing ruminal fermentation efficiency and enteric methane emission (≤ 17.5%).

Effect of increasing doses of neem (Azadirachta indica) seed oil on feed intake, nutrients digestibility, ruminal fermentation and nitrogen utilization of Omani sheep

This study was conducted to examine the effects of neem (Azadirachta indica) seed oil (NSO) on feed intake, ruminal fermentability, feed digestibility, nitrogen balance, and blood parameters in Omani sheep. Nine Omani male sheep (BW; 54.44 ± 8 kg/sheep) were used in a replicated 3 × 3 Latin Square design with three dietary treatments and three periods, with each period lasting 21 days. The animals were randomly assigned into three treatment groups: basal diet without NSO (control); 20 mL/sheep per day NSO (low dose) or 40 mL/sheep per day NSO (high dose). Sheep fed with high dose presented lower (p < 0.05) intake, fiber digestibility, and excreted N in urine. However, diet supplemented with high NSO dose had a lower (p < 0.05) ruminal acetate proportion, while increased (p < 0.05) ruminal propionate compared to the control group. Moreover, sheep offered with NSO showed a linear decrease (p = 0.052) in ruminal ammonia nitrogen (NH₃-N) concentration. The high dose increased (p < 0.05) blood glucose and cholesterol, while decreased urea nitrogen concentrations. Emission of predicted methane (CH₄) reduced (p = 0.007) by 13% for high dose compared to the control group. In conclusion, these results suggested that NSO is a potential feed additive with up to 20 ml/kg of DM alters rumen fermentation profile, decreased CH₄ production, feed digestibility, and nitrogen metabolism for sheep.

Cricket Meal (Gryllus bimaculatus) as a Protein Supplement on In Vitro Fermentation Characteristics and Methane Mitigation

Simple Summary

Protein sources of high quality and sustainability are found in insects. In many regions, insects are a primary food source, such as in Africa, South America, Asia, and Oceania. Insects are considered promising alternative feed sources, in particular as a source of protein. The use of edible insects as high-protein sources is widespread, and cricket has been proved to be a potential food and feed insect species. Cricket (Gryllus bimaculatus) also contain 54.10% crude protein, 6.90% crude fiber, 26.90% fat, and 78.90% total digestible nutrient, as well as a variety of essential amino acids, including methionine, lysine, histidine, valine, and leucine. In addition, insects have been investigated as a source of protein in diets of poultry, swine, and fish. However, there are currently little data on the utilization of insects as ruminant feed. The objective of this experiment was to conduct the effects of Cricket meal (Gryllus bimaculatus) (CM) as a protein replacement for soybean meal on in vitro fermentation end products, gas production, nutrient degradability, and methane mitigation.

Abstract

The aim of this work was to conduct the effects of cricket (Gryllus bimaculatus) meal (CM) as a protein supplement on in vitro gas production, rumen fermentation, and methane (CH₄) mitigation. Dietary treatments were randomly assigned using a completely randomized design (CRD) with a 2 × 5 factorial arrangement. The first factor was two ratios of roughage to concentrate (R:C at 60:40 and 40:60), and the second factor was the level of CM to replace soybean meal (SBM) in a concentrate ratio at 100:0, 75:25, 50:50, 25:75, and 0:100, respectively. It was found that in vitro DM degradability and the concentration of propionic (C₃) were significantly increased (p < 0.05), while the potential extent of gas production (a + b), acetate (C₂), acetate and propionate (C₂:C₃) ratio, and protozoal population were reduced (p < 0.05) by lowering the R:C ratio and the replacement of SBM by CM. In addition, rumen CH₄ production was mitigated (p < 0.05) with increasing levels of CM for SBM. In this study, CM has the potential to improve rumen fermentation by enhancing C₃ concentration and DM degradability, reduced methane production, and C₂:C₃ ratio. The effects were more pronounced (p < 0.05) at low levels of roughage.

Potential of graded doses of neem (Azadirachta indica) seed oil on ruminal fermentation characteristics, degradability, and methane formation in vitro

Neem (Azadirachta indica) belongs to Meliaceae family, represented mainly by trees, and widely cultivated and adapted in many tropical regions. The objective of this study was to evaluate the effect of increasing doses of neem seed oil (NSO) on ruminal methane (CH4) formation, diet degradability, and fermentation characteristics 24 h of in vitro incubation. Treatments were randomly designed to four doses of NSO supplemented to the basal diet (0, 20, 40, or 60 ml/kg DM). Increasing NSO dose resulted in a quadratic decrease (P < 0.05) in net gas (expressed as ml/g DM and ml/g TDOM) and CH4 (expressed as ml/g TDNDF) production, while CH4 (expressed as ml/g TDOM), acetate and propionate proportions decreased linearly confirming a dose-related effect. A quadratic increase in TDOM and linear increase (P = 0.023) in DNDF, NH3-N concentrations, and total protozoal counts were observed. However, a linear increase (P = 0.009) was found in the ruminal butyrate proportion and partitioning factor as dietary NSO supplementation increased. In conclusion, dietary NSO supplementation mediated some desirable fermentation patterns, reducing ruminal NH3-N concentration and CH4 production with some adverse effects on fiber degradability. However, practical research under long-term conditions is required for further investigation.

Effects of the natural sweetener rebaudioside A on intake, nutrient digestion, rumen fermentation, and blood biochemical parameters in adult goats during summer

The effects of dietary rebaudioside A inclusion on feed intake, digestion of nutrients, rumen fermentation, and blood biochemical parameters of goats were evaluated in a replicated 3 × 3 Latin square study. Nine adult goats during summer were fed a basal forage/concentrate-based diet and the forage was chopped rice straw. The three dietary treatments were 0, 350, and 700 mg rebaudioside A per kg chopped rice straw on a DM basis. No significant improvement was observed in dry matter intake (DMI) of forage and diet among treatments. Nutrient digestibility of DM and organic matter (OM) showed a significant trend (p < .10) across groups. Rebaudioside A inclusion significantly (p < .01) increased the concentration of total volatile fatty acids in the rumen, however, there were no differences in concentration of ruminal ammonia, and molar proportions of acetate, propionate, and butyrate. About blood metabolites, increasing rebaudioside A in the diet caused a quadratic response in glucose and total protein, and albumin concentrations. Under the conditions of this study, supplementation with rebaudioside A at 350 and 700 mg/kg forage did not improve consumption of rice straw-based diet in adult goats in summer. However, the responses in digestibility, rumen fermentation, and blood metabolites appear to indicate the potential of rebaudioside A as a bio-active substance in goats.

Effects of Essential Fatty Acid Supplementation on in vitro Fermentation Indices, Greenhouse Gas, Microbes, and Fatty Acid Profiles in the Rumen

This study estimated the effect of essential fatty acid (FA) supplementation on fermentation indices, greenhouse gases, microbes, and FA profiles in the rumen. The treatments used pure FAs consisting of C18:2n-6 FA (LA), C18:3n-3 FA (LNA), or a mixture of these FAs at 1:1 ratio (Combo). In vitro rumen incubation was performed in 50 mL glass serum bottles containing 2 mg of pure FAs, 15 mL of rumen buffer (rumen fluid+anaerobe culture medium = 1:2), and 150 mg of synthetic diet (411 g cellulose, 411 g starch, and 178 g casein/kg dry matter) at 39°C for 8 h with five replications and three blanks. In rumen fermentation indices, LA exhibited highest (P < 0.05) ammonia-N and total gas volume after 8 h of incubation. Furthermore, LA presented lower (P < 0.05) pH with higher (P < 0.05) total volatile fatty acid (P = 0.034) than Combo, while LNA was not different compared with those in the other treatments. Additionally, Combo produced highest (P < 0.05) CO₂ with lowest (P < 0.05) CH₄. In the early hours of incubation, LA improved (P < 0.005) Fibrobacter succinogenes and Ruminococcus flavefaciens, while LNA improved (P < 0.005) Ruminococcus albus. After 8 h of incubation, LNA had lower (P < 0.05) methanogenic archaea than LA and Combo but had higher (P < 0.05) rumen ciliates than LA. R. albus was higher (P < 0.05) in LA than in LNA and Combo. It was observed that the rate of biohydrogenation of n-6 and n-3 FAs was comparatively lowest (P < 0.05) in Combo, characterized by higher C18:2n-6 and/or C18:3n-3 FA and polyunsaturated FA (PUFA) concentrations with lower (P < 0.05) concentrations of C18:0 and saturated FA and the ratio of saturated FAs to PUFAs. Therefore, this study concluded that dietary C18:2n-6 could improve populations of fibrolytic bacteria and rumen fermentation indices, but dietary mixture of pure C18:2n-6 and C18:3n-3 is recommended because it is effective in reducing enteric methane emissions and resisting biohydrogenation in the rumen with less effect on rumen microbes.

Evaluating the Suitability of Hazelnut Skin as a Feed Ingredient in the Diet of Dairy Cows

Simple Summary

Agriculture is estimated to generate about 700 million tons of waste annually in the Eurpoean Union (EU). Most of the by-products derived from the agricultural industry become organic waste, thus resulting in the loss of valuable nutrients and bioactive compounds and causing environmental and economic issues. Increasing the efficiency of waste management is a major global challenge that must be met in order to minimize the abovementioned negative impacts. Some agro-industrial by-products can be valorized by their inclusion in feed formulations. Hazelnut skin is a by-product of the hazelnut industry. It is a good source of phenolic compounds, polysaccharides, unsaturated fatty acids, and vitamin E. In this study, we evaluated the productive performance of dairy cows in response to the inclusion of hazelnut skin in the diet. We observed no effects of hazelnut skin on either the milk production level or fat and protein contents. The oleic acid concentration in milk was strongly increased by including hazelnut skin in the cows’ diet. Improvements in the antioxidant activity and sustainability of milk production in terms of food–feed competition were also observed. These results are of practical application for feed manufacturers and farmers, as they support the inclusion of sustainable and low-cost feed ingredients in ruminant diets, with the aim of supporting the expected increase in livestock production in the upcoming years.

Abstract

Hazelnut skin (HS) was evaluated as a source of nutrients for dairy cows. In total, 26 Aosta Red Pied cows were divided into two balanced groups. All cows were fed hay ad libitum. The control group was also given 6 kg of concentrate, while the hazelnut skin group (HAZ) was given 1 kg of the same concentrate that was substituted by 1 kg of HS. The dry matter intake of the cows was reduced by the dietary inclusion of HS (p ≤ 0.001). The milk yield and main constituents were unaffected by treatment. Milk from HAZ cows showed decreased concentrations of de novo saturated fatty acids (FAs), odd- and branched-chain FA, α-linolenic acid, and long-chain n-3 FAs, as well as increased concentrations of stearic acid, oleic acid, linoleic acid, total monounsaturated FAs, trans biohydrogenation intermediates, and α–tocopherol. Replacing the concentrate with HS increased the human-inedible feed quota in the diet and improved the sustainability of milk production in terms of the food-feed competition. Our results suggest that it is possible to add economic value to organic waste from the hazelnut industry using HS as a feed ingredient for dairy cows, enhancing the feed efficiency and milk antioxidant activity and having expected impacts on the nutraceutical quality of milk fat.

Dynamic Alterations in Yak Rumen Bacteria Community and Metabolome Characteristics in Response to Feed Type

Current knowledge about the relationships between ruminal bacterial communities and metabolite profiles in the yak rumen is limited. This is due to differences in the nutritional and metabolic features between yak and other ordinary cattle combined with difficulties associated with farm-based research and a lack of technical guidance. A comprehensive analysis of the composition and alterations in ruminal metabolites is required to advance the development of modern yak husbandry. In the current study, we characterized the effect of feed type on the ruminal fluid microbiota and metabolites in yak using 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS). Bacteroidetes and Firmicutes were the predominant bacterial phyla in the yak rumen. At the genus level, the relative abundance of Bacteroidales BS11 gut group, Prevotellaceae UCG-003, Ruminococcaceae UCG-011, Bacteroidales RF16 group and Ruminococcaceae UCG-010 was significantly (P < 0.01) higher in the forage group compared to that in the concentrate group, while the concentrate group harbored higher proportions of Bacteroidales S24-7 group, Ruminococcaceae NK4A214, Succiniclasticum and Ruminococcus 2. Yak rumen metabolomics analysis combined with enrichment analysis revealed that feed type altered the concentrations of ruminal metabolites as well as the metabolic pattern, and significantly (P < 0.01) affected the concentrations of ruminal metabolites involved in protein digestion and absorption (e.g., L-arginine, ornithine, L-threonine, L-proline and β-alanine), purine metabolism (e.g., xanthine, hypoxanthine, deoxyadenosine and deoxyadenosine monophosphate) and fatty acid biosynthesis (e.g., stearic acid, myristic acid and arachidonic acid). Correlation analysis of the association of microorganisms with metabolite features provides us with a comprehensive understanding of the composition and function of microbial communities. Associations between utilization or production were widely identified between affected microbiota and certain metabolites, and these findings will contribute to the direction of future research in yak.

Effects of Dietary Stevioside Supplementation on Feed Intake, Digestion, Ruminal Fermentation, and Blood Metabolites of Goats

Simple Summary

This study evaluated the effects of stevioside, a natural sweetener that is an extract of Stevia, on feed intake and feeding behavior of goats. The results demonstrated that the consumption of forage was improved after supplementation with stevioside. Supplementation of stevioside resulted in improved total diet consumption of goats. These results are useful for ruminant producers to use natural sweeteners to regulate the intakes of animals.

Abstract

The objective of this study was to evaluate the effects of dietary inclusion of stevioside on feed intake, feeding behavior, nutrient digestion, rumen fermentation, and serum biochemical parameters in goats. Nine male Xiangdong black goats (21.8 ± 1.5 kg of body weight) were used in a replicated 3 × 3 Latin square. All goats were fed a basal diet including concentrate and forage (chopped rice straw). The three treatments were 0, 400, or 800 mg stevioside per kg chopped rice straw on a dry matter (DM) basis. Dry matter intake of forage and total diet linearly increased (p = 0.03 and p = 0.04) with increasing stevioside in the diet. There was no effect (p > 0.05) of stevioside inclusion in the diets on eating time, rumination time, or total mastication time for the goats. Total volatile fatty acid (VFA) concentration in the rumen responded quadratically (p < 0.01), decreasing from 0 to 400 mg/kg stevioside inclusion and increasing thereafter. The inclusion of steviosid in the diets promoted a quadratic increase in the apparent total tract digestibilities of neutral detergent fiber (NDF) (p = 0.02) and acid detergent fiber (ADF) (p = 0.01). Based on the results of this experiment, it could be concluded that supplementing goat diets with stevioside at 400 mg/kg to 800 mg/kg forage (about 270 to 541 mg/kg diet) resulted in increased dry intake of forage and total diet, suggesting that stevioside has positive potential as a feed additive to improve feed intake.

Tucumã Oil Shifted Ruminal Fermentation, Reducing Methane Production and Altering the Microbiome but Decreased Substrate Digestibility Within a RUSITEC Fed a Mixed Hay - Concentrate Diet

Tucumã oil is sourced from the fruit pulp of the tucumã tree and contains high concentrations of unsaturated fatty acids and carotenoids. Due to these properties it may have the potential to decrease enteric methane (CH4) from ruminants when included in the diet. The objective of this study was to determine the effect of oil mechanically extracted from the fruit pulp of tucumã on fermentation characteristics, CH4 production and the microbial community using the rumen stimulation technique. Treatments consisted of a control diet (forage:concentrate; 70:30), and tucumã oil included at 0.5 or 1.0% (v/v). Addition of tucumã oil linearly decreased (P < 0.01) dry matter disappearance. Total gas (mL/d) and carbon dioxide (CO2) production (mL/d, mL/g DM) were unaffected (P ≥ 0.36) to increasing addition of tucumã oil where 0.5% (v/v) of Tucumã oil numerically increased both variables. Acetate and butyrate percentages of total VFA were linearly decreased (P ≤ 0.01) and propionate and valerate percentages of total VFA were linearly increased (P < 0.01) by increasing concentrations of tucumã oil added to the substrate. The ratio of acetate to propionate was linearly decreased (P < 0.01) with increasing concentration of tucumã oil. Methane production (mL/d) was linearly decreased (P = 0.04) with increasing addition of tucumã oil to the substrate. Tucumã oil reduced the bacterial richness and diversity when included at 1.0% (v/v) in both solid- and liquid- associated microbes. The abundance of the genera Fibrobacter and Rikenellaceae RC9 gut group were decreased and Pyramidobacter, Megasphaera, Anaerovibrio, and Selenomonas were enriched by the addition of 1.0% tucumã oil. In conclusion, tucumã oil resulted in the favorable shift in fermentation products away from acetate toward propionate, decreasing the production of CH4 when tucumã oil was included at 1.0% (v/v), however, substrate digestibility was also inhibited. The rumen microbiota was also altered by the addition of tucumã oil.