Effects of different levels of rapeseed cake containing high glucosinolates in steer ration on rumen fermentation, nutrient digestibility and the rumen microbial community

Meta-Analysis of Incorporating Glucosinolates into Diets and Their Effects on Ruminant Performance, Ruminal Fermentation, Methane Emissions, Milk Composition, and Metabolic Biochemical Attributes

Brassica-derived feeds have been recognized for their economic and environmental benefits in ruminant nutrition. However, their utilization is constrained by the presence of glucosinolates and sulfur-containing compounds that exhibit both beneficial and adverse effects. This meta-analysis included 36 studies that evaluated the impact of glucosinolate intake on ruminant performance, nutrient digestibility, milk composition, and methane emissions. This analysis, conducted in accordance with PRISMA guidelines, revealed that glucosinolate supplementation resulted in a quadratic increase in milk urea nitrogen concentration (p = 0.017). Additionally, significant interactions between glucosinolate level and source influenced crude protein digestibility (p = 0.026). Milk composition parameters, including 4% fat-corrected milk, energy-corrected milk, milk protein, and lactose proportions, were significantly affected (p < 0.05). Furthermore, methane emissions (g/kg DMI) decreased quadratically with increasing glucosinolate intake (p = 0.003), with additional interactions observed between dietary treatments and animal species (p = 0.029). Propionate and isobutyrate concentrations increased in a quadratic and linear manner, respectively (p < 0.05). These findings suggest that glucosinolate-containing feed can enhance nutrient utilization and mitigate methane emissions in ruminants. However, the magnitude of these effects is dependent on the glucosinolate dosage, source, animal species, and dietary composition, necessitating further research to optimize their use in ruminant nutrition.

Response in Growth Performance, Carcass Traits, Physicochemical Properties, and Fatty Acid Composition of Dohne Merino Rams Fed Different Levels of Canola Meal

This study aimed to assess the effects of different inclusion levels of canola meal (CM) on growth performance, carcass characteristics, physicochemical properties, and fatty acid composition of Dohne Merino rams (DMRs). Forty DMRs, weighing 24±2.63 kg and aged 8-9 months, were individually housed and randomly assigned to one of four isonitrogenous and isoenergetic diets. The experimental diets contained 5% oil cake meal, soybean meal (SBM) or CM, CM replaced SBM at 0% (T1), 50% (T2), 75% (T3) and 100% (T4). The results revealed a quadratic increase in average daily feed intake as CM levels increase. Average daily gain and feed conversion ratio decreased. Blood urea nitrogen and total cholesterol showed a significant linear decline with increasing CM levels, while glucose-fasting, total protein, and albumin did not exhibit significant relationships. The carcass traits such as warm and cold dressing percentages, pH and temperature measurements, demonstrated a quadratic decrease with increasing CM inclusion levels. The physicochemical properties of the meat did not show significant relations, except for fat-free dry matter, which decreased quadratically. Fatty acids like capric, oleic, and eicosapentaenoic acids decreased significantly with CM levels, while margaric acid decreased linearly, and alpha-linolenic acid increased linearly. These findings suggest that restricting CM inclusion in sheep diets to below 5% could help mitigate adverse effects on growth performance. The possible antagonistic interaction between SBM and CM highlights the recommendation against combining CM with SBM in rations.

Effect of dietary protein source and Saccharina latissima on nutritional and safety characteristics of milk

BACKGROUND

Wheat distillers' grains (WDG) and seaweeds are recommended as alternative protein sources and enteric methane mitigators in dairy cow diets, respectively, but little is known about their impact on milk quality and safety. In the present study, 16 cows in four 4 × 4 Latin squares were fed isonitrogenous diets (50:50 forage:concentrate ratio), with rapeseed meal (RSM)-based or WDG-based concentrate (230 and 205 g kg-1 dry matter) and supplemented with or without Saccharina latissima.

RESULTS

Replacement of RSM with WDG enhanced milk nutritional profile by decreasing milk atherogenicity (P = 0.002) and thrombogenicity (P = 0.019) indices and the concentrations of the nutritionally undesirable saturated fatty acids - specifically, lauric (P = 0.045), myristic (P = 0.022) and palmitic (P = 0.007) acids. It also increased milk concentrations of the nutritionally beneficial vaccenic (P < 0.001), oleic (P = 0.030), linoleic (P < 0.001), rumenic (P < 0.001) and α-linolenic (P = 0.012) acids, and total monounsaturated (P = 0.044), polyunsaturated (P < 0.001) and n-6 (P < 0.001) fatty acids. Feeding Saccharina latissima at 35.7 g per cow per day did not affect the nutritionally relevant milk fatty acids or pose any risk on milk safety, as bromoform concentrations in milk were negligible and unaffected by the dietary treatments. However, it slightly reduced milk concentrations of pantothenate.

CONCLUSION

Feeding WDG to dairy cows improved milk fatty acid profiles, by increasing the concentrations of nutritionally beneficial fatty acids and reducing the concentration of nutritionally undesirable saturated fatty acids, while feeding seaweed slightly reduced pantothenate concentrations. However, when considering the current average milk intakes in the population, the milk compositional differences between treatments in this study appear relatively small to have an effect on human health. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Dynamic Changes in the Nutrient Digestibility, Rumen Fermentation, Serum Parameters of Perinatal Ewes and Their Relationship with Rumen Microbiota

Changes in physiological and biochemical parameters are crucial for the reproductive performance and health of perinatal ewes. This study investigated the temporal variations in feed intake, nutrient digestibility, serum parameters, and ruminal fermentation on days 21, 14, and 7 before lambing (Q21, Q14, and Q7) and days 3, 7, and 14 after lambing (H3, H7, and H14). The results showed that dry matter intake (DMI) and glucose (Glu) gradually decreased (p < 0.05) before lambing and increased (p < 0.05) after lambing. The digestibility of dry matter (DMD), crude protein (CPD), and acid detergent fiber (ADFD) increased (p < 0.05) before lambing, then decreased (p < 0.05) on day H3, and then increased (p < 0.05) on day H14. The rumen pH, NH3-N, and triglycerides (TG) gradually increased (p < 0.05) before lambing and were higher (p < 0.05) on day Q7 than after lambing. The concentrations of acetate, butyrate, and total volatile fatty acids (T-VFA) were lower (p < 0.05) on day Q7 than those on days Q21 and Q14, then increased (p < 0.05) after lambing. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) concentrations gradually decreased (p < 0.05) in perinatal ewes. BHBA and NEFA concentrations were lower (p < 0.05) on day Q21 than those from days Q14 to H14. The rumen microbiota compositions were different (p < 0.05) in perinatal ewes, and g_Anaerovibrio, g_Lachnobacterium, and g_Schwartzia were positively correlated (p < 0.05) with DMI, Glu, acetate, propionate, and T-VFA, and negatively correlated (p < 0.05) with LDL-C. g_Bacillus was negatively correlated (p < 0.05) with DMI, Glu, acetate, propionate, butyrate, and T-VFA, but positively correlated (p < 0.05) with rumen pH and LDL-C. In summary, the DMI, nutrient digestibility, rumen fermentation, and serum parameters changed during the perinatal period of ewes, and the changes in DMI, serum glucose, acetate, propionate, and T-VFA were related to the rumen bacteria.

Could natural phytochemicals be used to reduce nitrogen excretion and excreta-derived N2O emissions from ruminants?

Ruminants play a critical role in our food system by converting plant biomass that humans cannot or choose not to consume into edible high-quality food. However, ruminant excreta is a significant source of nitrous oxide (N2O), a potent greenhouse gas with a long-term global warming potential 298 times that of carbon dioxide. Natural phytochemicals or forages containing phytochemicals have shown the potential to improve the efficiency of nitrogen (N) utilization and decrease N2O emissions from the excreta of ruminants. Dietary inclusion of tannins can shift more of the excreted N to the feces, alter the urinary N composition and consequently reduce N2O emissions from excreta. Essential oils or saponins could inhibit rumen ammonia production and decrease urinary N excretion. In grazed pastures, large amounts of glucosinolates or aucubin can be introduced into pasture soils when animals consume plants rich in these compounds and then excrete them or their metabolites in the urine or feces. If inhibitory compounds are excreted in the urine, they would be directly applied to the urine patch to reduce nitrification and subsequent N2O emissions. The phytochemicals' role in sustainable ruminant production is undeniable, but much uncertainty remains. Inconsistency, transient effects, and adverse effects limit the effectiveness of these phytochemicals for reducing N losses. In this review, we will identify some current phytochemicals found in feed that have the potential to manipulate ruminant N excretion or mitigate N2O production and deliberate the challenges and opportunities associated with using phytochemicals or forages rich in phytochemicals as dietary strategies for reducing N excretion and excreta-derived N2O emissions.

Potentials of using dietary plant secondary metabolites to mitigate nitrous oxide emissions from excreta of cattle: Impacts, mechanisms and perspectives

Nitrous oxide (N₂O) is a potent greenhouse gas as well as the key component depleting the ozone sphere of the earth. Cattle have high feed and water intakes and excrete large amounts of urine and feces. N₂O can be produced from cattle excreta during storage and use as fertilizer. Mitigating the N₂O emissions from cattle excreta during production is important for protecting the environment and the sustainable development of the cattle industry. Feeding cattle with low-protein diets increases N utilization rates, decreases N excretion and consequently reduces N₂O emissions. However, this approach cannot be applied in the long term because of its negative impact on animal performance. Recent studies showed that dietary inclusion of some plant secondary metabolites such as tannins, anthocyanins, glucosinolates and aucubin could manipulate the N excretion and the urinary components and consequently regulate N₂O emissions from cattle excreta. This review summarized the recent developments in the effects of dietary tannins, anthocyanins and glucosinolates on the metabolism of cattle and the N₂O emissions from cattle excreta and concluded that dietary inclusion of tannins or anthocyanins could considerably reduce N₂O emissions from cattle excreta.

Microbiome-metabolomics analysis of the effects of decreasing dietary crude protein content on goat rumen mictobiota and metabolites

Objective

The objective of this study was to investigate the effects of decreasing dietary crude protein content on rumen fermentation, mictobiota, and metabolites in goats.

Methods

In an 84-day feeding trial, a total of twelve male Anhui white goat kids with initial body weight 15.9±1.13 kg were selected and randomly classified into two groups, feeding a normal crude protein diet (14.8% CP, NCP) or a low crude protein diet (12.0% CP, LCP). At the end of the experimental trial (on day 84), six animals were randomly selected from each group and were slaughtered to collect rumen fluid samples for the analysis of rumen fermentation parameters, microbiome, and metabolome.

Results

The concentrations of ammonia-nitrogen, total volatile fatty acid, acetate, and propionate were decreased (p<0.05) in the LCP group in comparison with those in the NCP group. The abundances of genera Prevotella, Campylobacter, Synergistetes, and TG5, which were associated with nitrogen metabolism, were lower (p<0.05) in the LCP group compared with those in the NCP group. The levels of 78 metabolites (74 decreased, 4 increased) in the rumen fluid were altered (p<0.05) by the treatment. Most of the ruminal metabolites that showed decreased levels in the LCP group were substrates for microbial protein synthesis. Metabolic pathway analysis showed that vitamin B6 metabolism was significantly different (p<0.05) in rumen fluid between the two treatments.

Conclusion

Decreased dietary protein level inhibited rumen fermentation through microbiome and metabolome shifts in goat kids. These results enhance our understanding of ruminal bacteria and metabolites of goat fed a low protein diet.

Effects of dietary inclusion with rapeseed cake containing high glucosinolates on nitrogen metabolism and urine nitrous oxide emissions in steers

Two consecutive trials were conducted to investigate the effects of glucosinolates (GLS) in rapeseed cake (RSC) on nitrogen (N) metabolism and urine nitrous oxide (N₂O) emissions in steers. In trial 1, 8 steers and 4 levels of RSC, i.e. 0, 2.7%, 5.4% and 8.0% dry matter (DM) (0, 6.0, 12.1, 18.1 μmol GLS/g DM) were allocated in a replicated 4 × 4 Latin square. In trial 2, the static incubation technique was used for measuring the N₂O emissions of the urine samples collected from trial 1. The results of trial 1 indicated that dietary inclusion of RSC decreased the digested N and increased the fecal N excretion (P < 0.01), whereas it did not affect the urinary N excretion, total N excretion and N retention (P > 0.10). Dietary inclusion of RSC decreased the urinary excretion of urea while it increased allantoin, total purine derivatives, the predicted rumen microbial N flow and thiocyanate (SCN) (P < 0.05). Dietary inclusion of RSC did not affect the plasma triiodothyronine and thyroxine while it down-regulated the plasma relative concentrations of 4-aminohippuric acid, 3α,7α-dihydroxycoprostanic acid, phosphatidylserine (14:0/16:0), 6β-hydroxyprogesterone, pyrrhoxanthinol, tatridin B, mandelonitrile rutinoside, taraxacoside (P < 0.05), and up-regulated hypoglycin B, neuromedin N (1-4), dhurrin, 5-deoxykievitone (P < 0.01). The results of trial 2 indicated that dietary RSC increased the steer urine N₂O-N fluxes, the ratio of N₂O-N to N application and the estimated steer urine N₂O-N emissions (P < 0.01). A close correlation was found between the estimated steer urine N₂O-N emissions and the output of urinary SCN (P < 0.001). In conclusion, dietary RSC increased the fecal N excretion, whereas it did not affect the urinary N excretion and the N retention rate in steers. Dietary RSC increased rather than decreased the urine N₂O-N emissions even though it decreased the urinary excretion of urea. The SCN excreted in urine could be the major factor in increasing the urine N₂O-N emissions. Whether other metabolites excreted into urine from RSC have an impact on the urine N₂O-N emissions in steers needs to be investigated in the future.