Ruminal Propionate Concentration Research Articles

87 Functional rumen microbiological survey of triplet-bearing Polypay ewes from parturition to weaning

Abstract Ewes transitioning from late gestation to early lactation face a number of challenges including physiological stress, dietary changes, and metabolic adaptations, particularly when bearing and rearing multiple offspring. Furthermore, rumen microbial composition and function has been correlated with milk production and nutrient density in transitioning dairy cows. However, limited research has evaluated the rumen microbial community of ewes during early lactation. The objective of this study was to conduct a functional microbiological survey of the ewe rumen from parturition to weaning. We hypothesized that ewes would experience fermentative disturbances post-parturition and that the rumen microbiota, and consequently, circulating metabolites, would recover over time. Nine multiparous Polypay ewes bearing triplets were fed a lactation diet consisting of alfalfa hay and concentrate mix to meet protein and energy requirements. One lamb of each triplet set was randomly selected and placed on milk replacer 24 h after birth. The two lambs remaining on the ewe were weaned at 56 d of age. Blood and rumen samples from ewes were collected via jugular venipuncture and oral intubation, respectively, at 2, 7, and 15 d of lactation in addition to at the time of weaning. Rumen bacterial functional guilds were enumerated via serial dilution. Ruminal short-chain fatty acids (SCFA) were quantified via HPLC and serum metabolites by LC-MS. All data were analyzed using PROC Mixed with repeated measures in SAS (v. 9.4, SAS Inst. Inc., Cary, NC). Total starch-utilizing bacteria remained steady during early lactation but increased 100-fold by weaning (P = 0.03). In contrast, the starch-utilizing guild sub-population lactobacilli increased 10-fold by d 15 of lactation (P < 0.01) and remained constant through weaning (P > 0.05). No differences were found in the viable number of rumen cellulolytic bacteria (P = 0.37) throughout the study. Ruminal propionate concentrations increased 35% (P = 0.04) from d 2 to weaning and serum propionate (36.8 ± 4.42 µM; P = 0.08) and glucose (59.8 ± 2.97 mg dL-1; P < 0.01) peaked on d 15 of lactation. While ruminal acetate did not fluctuate in early lactation, it increased 58% by weaning (P < 0.01) leading to an 88% increase in serum acetate (P < 0.01). Ruminal butyrate increased 49% by d 15 (P = 0.01) and this was reflected in a 7-fold increase in serum butyrate (P = 0.02). However, serum β-hydroxybutyrate did not differ from parturition through weaning (P = 0.51). Results of this experiment demonstrate that rumen bacterial functional guilds, as well as rumen and serum metabolites, were lowest two days post-parturition and increased over the course of lactation. This may suggest that ruminal fermentation is suppressed post-parturition, which could have implications for early lactation management strategies of triplet-bearing ewes.

Microbial composition, rumen fermentation parameters, enteric methane emissions, and lactational performance of phenotypically high and low methane-emitting dairy cows

This experiment was designed to investigate the relation of high and low methane-yield phenotypes with body weight (BW), dry matter intake (DMI), lactation performance, enteric CH4 emissions, and rumen fermentation parameters in lactating dairy cows. A total of 130 multi- and primiparous Holstein cows were screened for enteric CH4 emissions using the GreenFeed system (C-Lock Inc.). Out of these 130 cows, 5 were identified as phenotypically high (HM) and 5 as phenotypically low (LM) CH4 emitters. Cows in the LM group had lower daily enteric CH4 emissions than cows in the HM group (on average 346 vs. 439 g/d, respectively), lower CH4 yield (15.5 vs. 20.4 g of CH4/kg of DMI), and CH4 intensity (13.2 vs. 17.0 g of CH4/ kg of energy-corrected milk yield). Enteric emissions of CO2 and H2 did not differ between HM and LM cows. These 10 cows were blocked by parity, days in milk, and milk production, and were used in a 5-wk randomized complete block design experiment. Milk composition, production, and BW were also not different between LM and HM cows. The concentration of total volatile fatty acids in ruminal contents did not differ between CH4 phenotypes, but LM cows had a lower molar proportion of acetate (57 vs. 62.1%), a higher proportion of propionate (27.5 vs. 21.6%, respectively), and therefore a lower acetate-to-propionate ratio than HM cows. Consistently, the 16S cDNA analysis revealed the abundance of Succinivibrionaceae and unclassified Veillonellaceae to be higher in LM cows compared with HM cows, bacteria that were positively correlated with ruminal propionate concentration. Notably, Succinivibrionaceae trigger the formation of propionate via oxaloacetate pathway from phosphoenolpyruvate via Enzyme Commission: 4.1.1.49, which showed a trend to be higher in LM cows compared with HM cows. Additionally, LM cows possessed fewer transcripts of a gene encoding for methyl-CoM reductase enzyme compared with HM. In this study, low and high CH4-yield cows have similar production performance and milk composition, but total-tract apparent digestibility of organic matter and fiber fractions was lower in the former group of animals.

Essential Oils as a Dietary Additive for Small Ruminants: A Meta-Analysis on Performance, Rumen Parameters, Serum Metabolites, and Product Quality.

Simple SummaryEssential oils can be used to improve animal performance as well as the health and quality of livestock products. The aim of this study was to evaluate the effects of essential oil supplementation on animal performance, ruminal fermentation, blood metabolites, and meat and milk quality of small ruminants through a meta-analysis. Supplementation with essential oils improved weight gain, milk production and composition, oxidative stability of meat, and blood serum antioxidant enzyme activity. Additionally, essential oils decreased methane emissions. This suggests that the inclusion of essential oils in the diets of small ruminants could be used to improve animal performance and the quality of meat and milk, in addition to reducing the environmental impact and oxidative stress of the animals.There is an increasing pressure to identify natural feed additives that improve the productivity and health of livestock, without affecting the quality of derived products. The objective of this study was to evaluate the effects of dietary supplementation with essential oils (EOs) on productive performance, rumen parameters, serum metabolites, and quality of products (meat and milk) derived from small ruminants by means of a meta-analysis. Seventy-four peer-reviewed publications were included in the data set. Weighted mean differences (WMD) between the EOs treatments and the control treatment were used to assess the magnitude of effect. Dietary inclusion of EOs increased (p < 0.05) dry matter intake (WMD = 0.021 kg/d), dry matter digestibility (WMD = 14.11 g/kg of DM), daily weight gain (WMD = 0.008 kg/d), and feed conversion ratio (WMD = −0.111). The inclusion of EOs in small ruminants’ diets decreased (p < 0.05) ruminal ammonia nitrogen concentration (WMD = −0.310 mg/dL), total protozoa (WMD = −1.426 × 105/mL), methanogens (WMD = −0.60 × 107/mL), and enteric methane emissions (WMD = −3.93 L/d) and increased ruminal propionate concentration (WMD = 0.726 mol/100 mol, p < 0.001). The serum urea concentration was lower (WMD = −0.688 mg/dL; p = 0.009), but serum catalase (WMD = 0.204 ng/mL), superoxide dismutase (WMD = 0.037 ng/mL), and total antioxidant capacity (WMD = 0.749 U/mL) were higher (p < 0.05) in response to EOs supplementation. In meat, EOs supplementation decreased (p < 0.05) the cooking loss (WMD = −0.617 g/100 g), malondialdehyde content (WMD = −0.029 mg/kg of meat), yellowness (WMD = −0.316), and total viable bacterial count (WMD = −0.780 CFU/g of meat). There was higher (p < 0.05) milk production (WMD = 0.113 kg/d), feed efficiency (WMD = 0.039 kg/kg), protein (WMD = 0.059 g/100 g), and lactose content in the milk (WMD = 0.100 g/100 g), as well as lower somatic cell counts in milk (WMD = −0.910 × 103 cells/mL) in response to EOs supplementation. In conclusion, dietary supplementation with EOs improves productive performance as well as meat and milk quality of small ruminants. In addition, EOs improve antioxidant status in blood serum and rumen fermentation and decrease environmental impact.

The effect of ensiled paulownia leaves in a high-forage diet on ruminal fermentation, methane production, fatty acid composition, and milk production performance of dairy cows

BackgroundThe use of industrial by-products rich in bioactive compounds as animal feeds can reduce greenhouse gas production. Paulownia leaves silage (PLS) was supplemented to dairy cows' diet and evaluated in vitro (Exp. 1; Rusitec) and in vivo (Exp. 2, cannulated lactating dairy cows and Exp. 3, non-cannulated lactating dairy cows). The study investigated the PLS effect on ruminal fermentation, microbial populations, methane production and concentration, dry matter intake (DMI), and fatty acid (FA) proportions in ruminal fluid and milk.ResultsSeveral variables of the ruminal fluid were changed in response to the inclusion of PLS. In Exp. 1, the pH increased linearly and quadratically, whereas ammonia and total volatile fatty acid (VFA) concentrations increased linearly and cubically. A linear, quadratic, and cubical decrease in methane concentration was observed with increasing dose of the PLS. Exp. 2 revealed an increase in ruminal pH and ammonia concentrations, but no changes in total VFA concentration. Inclusion of PLS increased ruminal propionate (at 3 h and 6 h after feeding), isovalerate, and valerate concentrations. Addition of PLS also affected several populations of the analyzed microorganisms. The abundances of protozoa and bacteria were increased, whereas the abundance of archaea were decreased by PLS. Methane production decreased by 11% and 14% in PLS-fed cows compared to the control in Exp. 2 and 3, respectively. Exp. 3 revealed a reduction in the milk protein and lactose yield in the PLS-fed cows, but no effect on DMI and energy corrected milk yield. Also, the PLS diet affected the ruminal biohydrogenation process with an increased proportions of C18:3 cis-9 cis-12 cis-15, conjugated linoleic acid, C18:1 trans-11 FA, polyunsaturated fatty acids (PUFA), and reduced n6/n3 ratio and saturated fatty acids (SFA) proportion in milk. The relative transcript abundances of the 5 of 6 analyzed genes regulating FA metabolism increased.ConclusionsThe dietary PLS replacing the alfalfa silage at 60 g/kg diet can reduce the methane emission and improve milk quality with greater proportions of PUFA, including conjugated linoleic acid, and C18:1 trans-11 along with reduction of SFA.Graphical Graphical abstract of the experimental roadmap

Effects of Different Roughages on Growth Performance, Nutrient Digestibility, Ruminal Fermentation, and Microbial Community in Weaned Holstein Calves.

This study aimed to assess the effects of feeding with different forage sources and starter concentrations on growth performance, nutrient digestibility, ruminal fermentation, and the microbial community in weaned Holstein calves. A total of 54 Holstein calves (body weight (BW) = 77.50 ± 5.07 kg; age = 70 ± 2.54 days) were assigned to 1 of 3 treatment groups (n = 18/group) that were offered diets with different forages: (1) peanut vine (PV), (2) oat hay (OH), or (3) an alfalfa hay + oat hay combination (alfalfa hay:oat hay =1:1, AO). Starter and forage intakes were recorded daily, while BW and growth parameters were assessed at 15-day intervals. The apparent digestibility of nutrients was determined. Ruminal fluid samples were collected and used to detect relevant indicators. A difference was observed for the forage × age interaction for all feed, nutrient intake, BW, ADG, and body structure parameters (P < 0.05). The final BW, average daily feed intake (ADFI), and average daily gain of the PV calves were higher than those of calves from the other groups (P < 0.05). The ruminal propionate concentration evidently increased in calves of the AO group (P < 0.05). The abundances of Rikenellaceae_RC9_gut_group and Shuttleworthia showed distinct responses to feeding with different forages (P < 0.05) at the genus level. The relative abundance of Shuttleworthia was negatively related to rumen pH and acid detergent fiber digestibility (P < 0.05) and strongly positively related to propionate concentration (P < 0.01). A positive correlation was found between Ruminococcus_1 abundance and butyrate concentration and neutral detergent fiber digestibility (P < 0.05). The relative abundances of Succiniclasticum and Prevotella_7 were negatively related to butyrate concentration (P < 0.05). In conclusion, there was an interaction between the factors (forage × age). The peanut vine used as a forage source promoted a higher starter concentrate intake compared to other diets and increased with the calves' age. The growth performance and rumen bacterial community of the calves were further improved. These results indicate that peanut vine can be used as the main source of forage in the diets of weaned calves.

Probiotic effect of ferulic acid esterase-producing Lactobacillus plantarum inoculated alfalfa silage on digestion, antioxidant, and immunity status of lactating dairy goats.

A feeding experiment was conducted to determine the effects of inoculating alfalfa silage with a ferulic acid esterase-producing inoculum on feed digestibility, rumen fermentation, antioxidant, and immunity status of lactating dairy goats. Twenty dairy goats were distributed into 2 experimental groups consisting of control diet (Lp MTD/1, including Lactobacillus plantarum MTD/1 inoculated silage) against diet containing silage treated with ferulic acid esterase-producing L. plantarum A1 (Lp A1). Alfalfa silage inoculated with a ferulic acid esterase-producing Lp A1 had better fermentation quality than the Lp MTD/1 inoculation. The application of Lp A1 improved silage antioxidant capacity as indicated by greater total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and glutathion peroxidase (GSH-Px) activities in Lp A1 treated silage versus Lp MTD/1 treatment. Compared with Lp MTD/1 treated group, inoculation of silage with Lp A1 increased apparent total tract digestibility of dietary dry matter, organic matter and crude protein, and ruminal concentrations of total volatile fatty acids, acetate, propionate and isobutyrate as well. The results of current study also demonstrated improved antioxidant capacity and immune performance of dairy goats with Lp A1 inoculation. Feeding Lp A1-treated silage increased dairy goats' serum antioxidase activity, such as T-AOC, SOD, GSH-Px and catalase, and the serum concentration of immunoglobulin A, while decreased tumor necrosis factor α, interleukin (IL)-2 and IL-6. In addition, compared with Lp MTD/1, diet containing alfalfa silage inoculated with Lp A1 endowed dairy goats' milk with greater fat and protein contents, improved dairy goat milk quality without affecting feed efficiency.

Responses of Lactation, Rumen Fermentation and Blood Biochemical Parameters with Increasing Dietary Inulin Supplementation in Mid-Lactation Dairy Cows

Effects of dietary supplementation of inulin in dairy cows were investigated in this study. Thirty-six mid-lactation Holstein dairy cows were randomly divided into six groups with six cows per group and offered a total mixed ration supplemented with 0 (control), 50, 150, 200, 250 and 350 g/d inulin per head, respectively. The animals were pre-fed for 2 weeks before rumen fluid, milk and blood samples were collected weekly for 3 weeks. With increasing inulin doses, milk yield (p &lt; 0.01) and milk fat concentration (p = 0.04) were linearly increased, while milk urea nitrogen (p &lt; 0.01) and somatic cell count (p = 0.04) were linearly decreased. Linear increases were also detected in the proportions of milk saturated fatty acids (p &lt; 0.01) and polyunsaturated fatty acids (p = 0.04); however, milk monounsaturated fatty acids were linearly decreased (p = 0.04). The ruminal concentrations of acetate, propionate and butyrate increased, while the ruminal pH and the concentration of NH3-N reduced at a decreasing rate with increasing inulin doses (p &lt; 0.01). Moreover, the concentrations of lactic acid (p = 0.03) and total volatile fatty acids (p &lt; 0.01) were linearly upregulated. There were linear increases in the serum concentrations of superoxide dismutase (p = 0.02), immunoglobin G (p &lt; 0.01), immunoglobin M (p = 0.04), interleukin-2 (p &lt; 0.01) and interleukin-10 (p = 0.04); quadratic increases in serum total protein (p &lt; 0.01) and albumin (p = 0.02) and linear decreases in serum total cholesterol (p = 0.02), triglyceride (p &lt; 0.01) and malondialdehyde (p &lt; 0.01). The results indicated that inulin increased milk production, shifted milk fatty acid profile, upregulated rumen volatile fatty acid concentration, and enhanced antioxidant and immunity function in dairy cows in a dose-dependent manner.

Monensin and concentrate supplementation level affect forage ruminal measurements and forage in situ disappearance of bermudagrass fed to beef cattle

The objective of this study was to evaluate the effects of monensin and concentrate supplementation levels on bermudagrass (Cynodon dactylon) in situ disappearance and ruminal measurements. The experiment was conducted in Ona, Florida, and treatments were the factorial arrangement of 2 supplementation levels [0.4 (low) or 4 kg/d (high)] and 2 monensin levels (0 or 20 mg/kg of the DMI) distributed in a Latin square design. The supplement was 17.1% CP and 79.1% TDN. Steers receiving the higher supplementation level had greater (P = 0.01) total DMI (1.4 vs. 1.0 ± 0.1% BW), but there was no difference in forage DMI (P = 0.72, mean = 1.0 ± 0.1% BW). Monensin did not affect total DMI or forage DMI (P ≤ 0.74). There was a monensin × supplementation level interaction on ruminal propionate concentration. The interaction occurred because there was no effect (P = 0.64) of monensin with low supplementation (mean = 12 ± 1.2 mol/100 mol); however, monensin increased (P = 0.01) propionate on the high supplementation level (19 vs. 15 ± 1.5 mol/100 mol). There was no effect (P > 0.05) of monensin on potential DM, CP, and NDF disappearance; however, greater supplementation level increased (P < 0.03) potential DM and NDF disappearance. Monensin did not change forage disappearance measurements but increased ruminal propionate concentrations in steers receiving higher supplementation level. Higher supplementation level was effective to increase total DMI and forage DM and NDF disappearance.

Effect of protein and glucogenic precursor supplementation on forage digestibility, serum metabolites, energy utilization, and rumen parameters in sheep

Supplementation of glucogenic precursors in roughage diets may increase production responses due to improved efficiencies of nutrient utilization. Therefore, the objective of this study was to determine the effect of source of supplemental glucogenic potential (GP) on forage digestibility, serum metabolites, energy utilization, and rumen parameters of growing wethers consuming a roughage diet (8.8% crude protein, 71.4% ash-free neutral detergent fiber). Crossbred wethers (49.1 ± 4.7 kg initial BW; n = 16) were utilized in a 4 × 4 replicated Latin Square design with four periods of 21 d. Supplements were designed to supplement increasing amount of GP: 1) no supplementation (CON; 0 g), 2) 40 g of calcium propionate (CAP; 30 g of GP), 3) 70 g of blood meal + 100 g of feather meal (BF; 40 g of GP), or 4) combination of CAP and BF (COMBO; 70 g of GP). Total fecal and urine collection was conducted from days 13–17 to calculate digestibility estimates and urinary losses. An acetate tolerance test was administered on day 17 to determine the effect of GP on acetate clearance. Blood samples were collected on day 19 and were analyzed for serum concentrations of glucose, urea N (SUN), non-esterified fatty acids, and amino acids. Rumen fluid was collected on day 21 to determine supplementation effects on ruminal volatile fatty acid (VFA) and ammonia concentrations. Wethers receiving BF and COMBO supplementation had greatest (P ≤ 0.01) DM and OM total tract digestibility. Supplementation did not affect (P ≥ 0.37) NDF digestibility or digestible energy. Urinary nitrogen excretion was greatest (P = 0.02) for BF and COMBO. Circulating serum essential amino acid concentration was increased (P < 0.01) in BF and COMBO compared to CAP and CON. In addition, BF and COMBO had increased (P < 0.01) SUN concentrations compared to CAP and CON. Acetate half-life was not affected (P = 0.39) by supplementation strategy. However, area under the curve (AUC) for acetate was decreased (P = 0.04) with supplementation of BF and COMBO compared to CON-fed wethers. Ruminal propionate concentration was increased (P ≤ 0.01) for wethers fed CAP and COMBO supplementation, which resulted in decreased (P ≤ 0.01) A:P ratio. Overall, these results indicate that the increased propionate supply by providing propionate salts did not result in a protein sparing impact or increased N retention.

Whole corn grain-based diet and levels of physically effective neutral detergent fiber from forage (pefNDF) for feedlot lambs: Digestibility, ruminal fermentation, nitrogen balance and ruminal pH

The present study evaluates the increasing levels of physically effective neutral detergent fiber of forage (pefNDF) in a whole corn grain-based diet on DMI, the apparent digestibility of nutrients, the nitrogen balance, and ruminal fermentation. Thirty ruminally cannulated Dorper × Santa Inês ram lambs, castrated, with 30.14 ± 3.01 kg of initial BW and approximately 3-month-old were used. The experimental design was in a randomized complete block (5 treatments and 6 blocks), defined by BW and age at the beginning of the experiment. The experimental diets were: CONT (positive control) – ground corn-based diet with 72 g/kg of pefNDF; 0pefNDF – whole corn grain-based diet without forage; 36pefNDF – whole corn grain-based diet with 36 g/kg of pefNDF; 72pefNDF – whole corn grain-based diet with 72 g/kg of pefNDF; 108pefNDF – whole corn grain-based diet with 108 g/kg of pefNDF (DM basis). The experimental diets were formulated to be isonitrogenous. The treatments did not affect the DMI. The increasing levels of pefNDF decreased the digestibility of DM, OM (P = 0.03) and TDN (P < 0.001). Whole corn grain-based diets associated or not with pefNDF showed higher digestibility of DM and OM (P < 0.01) than CONT. On the other hand, 0pefNDF showed higher digestibility of TDN (P < 0.01) than CONT. Ruminal propionate concentration of lambs fed CONT was lower than 0pefNDF (P = 0.04), while the isobutyrate concentration was higher (P = 0.01) for lambs on the CONT compared to lambs that received the other diets. The CONT had a lower ruminal pH (hour 9, P = 0.04; hour 12, P < 0.01) and ruminal pH area under the curve (hour 9, P = 0.03; hour 12, P < 0.02) when compared to the 0pefNDF. Additionally, at hours 9 (P < 0.02), 12 (P < 0.001) and 16 (P = 0.001) the lambs of the CONT had lower ruminal pH and pH area under the curve compared to lambs fed diets with whole corn with pefNDF. At hour 24, there was a linear increase in ruminal pH (P = 0.02) and ruminal pH area under the curve (P < 0.01) according to the increase in pefNDF levels in the diets. In diets with whole corn, the addition of pefNDF is not recommended, considering that no benefits were observed for nutrient digestibility, ruminal fermentation or nitrogen balance. The diet consisting of whole corn proved to be suitable for finishing lambs, as it enhanced DM and OM digestibility without clinical evidence of ruminal acidosis.

Active dry yeast supplementation improves the growth performance, rumen fermentation, and immune response of weaned beef calves.

The objective of this experiment was to investigate the potential benefits of active dry yeast (ADY) on the growth performance, rumen fermentation, nutrient digestibility, and serum parameters of weaned beef calves. Thirty Simmental crossbred male calves (body weight = 86.47 ± 4.41 kg and 70 ± 4 d of age) were randomly divided into 2 groups: control (CON) (fed basal ration) and ADY (fed basal ration and 5 g/d ADY per calf). The dietary concentrate-to-roughage ratio was 35:65. All the calves were regularly provided rations 3 times a day at 07:00, 13:00, and 19:00 and had free access to water. The experiment lasted for 60 d. The average daily gain of ADY group was higher (P = 0.007) than that of the CON group, and the ratio of feed intake to average daily gain in the ADY group was reduced (P = 0.022) as compared to the CON group. The concentration of ruminal ammonia-N was higher (P = 0.023) in the CON group than that in the ADY group, but an opposite trend of microbial protein was found between the 2 groups. Also, the ruminal concentrations of propionate and butyrate were higher (P < 0.05) in the ADY group than those in the CON group. Calves fed ADY exhibited higher (P < 0.05) crude protein and neutral detergent fiber digestibility. Supplementation of ADY increased (P < 0.05) the contents of glucose, glutathione peroxidase, superoxide dismutase, immunoglobulin A, immunoglobulin M, and interleukin 10 in the serum of calves, but an opposite trend was observed in malondialdehyde, interleukin 1 beta, and tumor necrosis factor alpha contents between the 2 groups. In conclusion, dietary supplementation with ADY could improve the growth performance, rumen fermentation, nutrient digestibility, antioxidant ability, and immune response of weaned beef calves.

Effects of Dietary Tannins’ Supplementation on Growth Performance, Rumen Fermentation, and Enteric Methane Emissions in Beef Cattle: A Meta-Analysis

The environmental sustainability of beef production is a significant concern within the food production system. Tannins (TANs) can be used to minimize the environmental impact of ruminant production because they can improve ruminal fermentation and ruminants’ lifetime performances and mitigate methane (CH4) emissions. The objective of this study was to evaluate the effects of dietary supplementation with TANs as sustainable natural alternative to reduce the environmental impact on growth performance, rumen fermentation, enteric CH4 emissions, and nitrogen (N) use efficiency of beef cattle through a meta-analysis. A comprehensive search of studies published in scientific journals that investigated the effects of TANs’ supplementation on the variables of interest was performed using the Scopus, Web of Science, and PubMed databases. The data analyzed were extracted from 32 peer-reviewed publications. The effects of TANs were assessed using random-effects statistical models to examine the standardized mean difference (SMD) between TANs’ treatments and control (non-TANs). The heterogeneity was explored by meta-regression and subgroup analysis was performed for the covariates that were significant. TANs’ supplementation did not affect weight gain, feed consumption, feed efficiency, or N use efficiency (p &gt; 0.05). However, it reduced the concentration of ammonia nitrogen in rumen (SMD = −0.508, p &lt; 0.001), CH4 emissions per day (SMD = −0.474, p &lt; 0.01) and per unit dry matter intake (SMD = −0.408, p &lt; 0.01), urinary N excretion (SMD = −0.338, p &lt; 0.05), and dry matter digestibility (SMD = −0.589, p &lt; 0.001). Ruminal propionate (SMD = 0.250) and butyrate (SMD = 0.198) concentrations and fecal N excretion (SMD = 0.860) improved in response to TANs’ supplementation (p &lt; 0.05). In conclusion, it is possible to use TANs as a CH4 mitigation strategy without affecting cattle growth rate. In addition, the shift from urinary to fecal N may be beneficial for environment preservation, as urinary N induces more harmful emissions than fecal N. Therefore, the addition of tannins in the diet of beef cattle could be used as a sustainable natural alternative to reduce the environmental impact of beef production.

Modulation of ruminal pH, milk fat secretion, and biohydrogenation intermediates by alkalizing agents in dairy cows fed starch-rich diets

We aimed to evaluate the effects of magnesium-based supplements and NaHCO3 on ruminal fermentation parameters, milk fatty acid (FA) profile, and milk fat synthesis in dairy cows fed high-starch diets. Eight second-lactation Holstein dairy cows (4 ruminally-cannulated) averaging 97 ± 12 days in milk and 33 ± 2.5 kg/d of milk were assigned to a replicated 4 × 4 Latin square design with 21-d periods. Cows were fed the following isoenergetic diets (1.64 Mcal/kg DM): (1) the control [342 g/kg starch on dry matter (DM) basis] without any buffering or alkalizing agent, (2) the control plus 8 g/kg DM NaHCO3, (3) the control plus 4 g/kg DM MgO, and (4) the control plus 8 g/kg DM CaMg(CO3)2. Ruminal pH was continuously measured for 72-h in each period using indwelling pH electrodes. Mean ruminal pH was not affected by treatments, but the duration of ruminal pH below 5.8 was shorter (P < 0.01) in cows fed NaHCO3, MgO, or CaMg(CO3)2 diets compared with those fed the control whereas NaHCO3 was more effective than magnesium-based supplements. Similar ability observed for CaMg(CO3)2 and MgO with respect to the duration of ruminal pH below 5.8 responses. The ruminal molar proportion of acetate and acetate-to-propionate ratio was greater (P < 0.05) with magnesium-based supplements and NaHCO3 compared with the control diet. However, the ruminal propionate concentration decreased (P = 0.02) with magnesium-based supplements and NaHCO3 versus the control. The milk proportion and yield of trans-10 C18:1 and total trans-FA dropped and the trans-10/trans-11 C18:1 ratio decreased further, when cows were fed magnesium-based supplements and NaHCO3 compared with the control diet (P < 0.01). Also, adding NaHCO3, MgO, or CaMg(CO3)2 significantly increased yields of trans-11 C18:1 (P < 0.01), de novo (P < 0.01), mixed (P = 0.04), and also preformed FA (P < 0.01) compared with the control diet. The yields of milk, 3.5% fat-corrected, and energy-corrected milk increased (P < 0.01) in cows fed magnesium-based supplements and NaHCO3 due to the improved concentration of milk fat. Overall, supplementing NaHCO3, MgO, and CaMg(CO3)2 in a high-starch diet appears to promote milk fat output by modulating diurnal ruminal pH and ruminal volatile fatty acids profile in dairy cows. Also, it can be concluded that CaMg(CO3)2 has similar ability of MgO in promoting milk fat synthesis and alleviating the time ruminal pH remains below 5.8. Therefore, CaMg (CO3)2 can be used effectively as an alkalizing agent in dairy cow diets containing high-starch and helps to reduce the costs of consumption of the most popular dietary buffers or alkalizers such as NaHCO3 and MgO.

Meat goat diet supplementation with crude glycerine: Ruminal fermentation metabolism, blood chemistry profile, animal performance and carcass traits.

The objective of this experiment was to determine the effects of feeding varying levels of crude glycerine (CG) on dry matter intake (DMI), animal performance, carcass traits and rumen volatile fatty acids (VFA) concentration in meat goats. Twenty-four intact male Boer goats (23.9±1.0kg initial BW and 4-5months of age) were randomly assigned to one of four experimental diets (n=6) containing 30% bermudagrass hay plus 70% concentrate mix with 0, 5, 10 or 15% CG in the diet on an as-fed basis, substituted for the corn portion of the concentrate. Feed offered and refusals were monitored daily for 84days. Goats were weighed at 28-days interval. Blood and rumen samples were collected on day 84. At the end of the 84-days feeding period, goats were harvested, and carcass characteristics measured. Feed intake, average daily gain (ADG), gain-to-feed ratio (G:F), carcass traits and VFA concentrations were analysed as a completely randomized design. The CG did not influence animal body weight (BW) changes, ADG and G:F ratio but tended to (p=0.06) decrease DMI. Molar per cent propionic acid increased linearly (p<0.05) with increasing CG. The acetate: propionate (A:P) ratio decreased (p<0.05) with increasing amounts of CG in the diet. The CG addition tended to increase (p=0.09) the longissimus muscle (LM area) in meat goats. In conclusion, CG can replace corn in diet for growing meat goats when fed up to 15% of diet, improving ruminal propionate concentration, but decreasing A:P ratio without affecting animal performance and carcass traits.

Diet-ruminal microbiome-host crosstalk contributes to differential effects of calf starter and alfalfa hay on rumen epithelial development and pancreatic α-amylase activity in yak calves

Dietary supplementation of alfalfa hay or calf starter during the preweaning period was beneficial to the gastrointestinal development in dairy calves and lambs. In the present study, we designed 2 experiments using weaning with calf starter and alfalfa hay to investigate the diet-ruminal microbiome-host crosstalk in yak calves by analyzing the ruminal microbiota and rumen epithelial transcriptome. During the preweaning period, supplementation with either alfalfa hay or the starter significantly promoted animal growth and organ development in yak calves, including increases in body weight, body height, body length, chest girth, and development of liver, spleen, and thymus. These improvements could be attributed to increased dry matter intake, rumen fermentation, and development. Butyrate concentration increased in yak calves fed alfalfa hay or the starter, which could further promote ruminal epithelium development. Using 16S rRNA gene amplicon sequencing, we determined that butyrate-producing genera were increased by the supplementation with alfalfa hay or the starter. Transcriptomic analysis of the rumen epithelia revealed that the PI3K-Akt signaling pathway, which is critical in mediating many aspects of cellular function such as cell growth, was upregulated in response to alfalfa hay or the starter supplementation. The starter supplementation also increased the jejunal α-amylase activity, whereas alfalfa hay supplementation reduced the ileal α-amylase activity. Furthermore, the co-supplementation of both the starter and alfalfa hay reduced intestinal α-amylase activity. The starter increased ruminal propionate concentration, whereas alfalfa hay exhibited the opposite trend. The observed opposite effects of the starter and alfalfa hay on rumen propionate concentration corresponded with up- and downregulation, respectively, of the ruminal cholecystokinin involved in pancreatic secretion pathway, and thereby increased and decreased pancreatic α-amylase activity. In conclusion, both alfalfa hay and the starter could promote the growth and ruminal epithelial development of yak calves. The starter and alfalfa hay also differentially affected the intestinal α-amylase activities due to their different chemical components and different effects on ruminal fermentation, especially the ruminal propionate production.

Soybean oil supplementation and alfalfa hay inclusion in starter feed of Holstein dairy calves: growth performance, digestibility, ruminal fermentation and urinary purine derivatives

Forty newborn Holstein female calves (BW = 39.9 ± 2.1 kg) were assigned to 1 of 4 treatment groups (each consisting of 10 animals) in a 2 × 2 factorial arrangement of supplemental soybean oil [0 vs. 3% soybean oil (SBO) on dry matter basis] and forage level [0 vs. 15% alfalfa hay (AH) on dry matter basis] to evaluate the interaction effect of supplemental fat and forage feeding level in starter feed of dairy calves. Treatments were; (1) neither SBO supplementation nor AH inclusion (NSBO-NAH); (2) SBO supplementation but no AH included (SBO-NAH); (3) no SBO supplementation but AH included (NSBO-AH); and (4) SBO supplementation with AH (SBO-AH). Calves had ad-libitum access to water and starters throughout the study and weaned on day 63 of age but remained in the study until day 73 of age. The results showed that SBO supplementation reduced starter intake, average daily gain (tendency) and faecal consistency compared to un-supplemented diets. The lowest digestibility for neutral detergent fibre and crude protein, as well as the lowest wither height and volatile fatty acid production, were found for SBO-AH diet among experimental treatments. Moreover, the lowest urinary purine derivatives excretion but the highest urinary nitrogen excretion found in SBO-AH diet indicated the lowest nitrogen utilisation efficiency among experimental treatments. In summary, based on the current study condition, because the negative effects of SBO supplementation were exacerbated when AH was incorporated in the starter feed, concurrent feeding of SBO and AH is not recommendable in young calves. HIGHLIGHTS Supplemental soybean oil and alfalfa hay inclusion in starter feed of dairy calves was evaluated. Supplementation of SBO reduced crude protein digestibility and ruminal propionate concentration and caused looser faecal consistency. The inclusion of AH exacerbated the negative effects of SBO supplementation on ruminal fermentation and microbial activity. Concurrent supplementation of SBO and AH inclusion is not recommendable in dairy calves.

Replacing alfalfa hay with dry corn gluten feed alters eating behavior, nutrient digestibility, and performance of lactating dairy cows

The objective of this trial was to determine the amount of alfalfa hay (AH) in low forage diets that could be replaced with dried corn gluten feed (DCGF) without negatively altering eating behaviour, ruminal fermentation, nutrient digestibility, and performance of lactating dairy cows. Eight multiparous Holstein cows were used in a replicated 4 × 4 Latin square design experiment. Treatments included (dry matter [DM] basis): 18.81% AH without DCGF (0DCGF,); 12.53% AH and 6.26% DCGF (6DCGF); 6.26% AH and 12.53% DCGF (12DCGF); and 0% AH and 18.81% DCGF (18 DCGF). Diet particle size and physically effective neutral detergent fibre declined linearly (p < .001) as DCGF replaced AH resulting in a linear decrease (p < .001) in time (min/d) spent eating, ruminating, and chewing. As DCGF replaced AH, ruminal pH decreased linearly (p = .003) and total VFA concentrations increased linearly (p = .02) tending to be highest (p = .062) for 12DCGF. Ruminal acetate and butyrate, and plasma β-hydroxybutyrate concentrations declined linearly (p = .001) whereas ruminal propionate concentration increased linearly (p = .001) as DCGF increased. Dry matter intake (DMI; p = .001) and nutrient digestibility increased linearly (p < .05) and tended to be greatest (p < .10) for 12DCGF. Milk yield (MY; p = .016) and protein yield (p = .001) increased linearly, but milk fat yield declined as DCGF replaced 6 and 12% of AH and decreased more when DCGF replaced all AH resulting in a quadratic response (p = .041). Results of this trial suggest that replacing 12% of the AH with DCGF increases MY because of higher DMI and nutrient digestibility, but replacing all of the AH with DCGF reduces milk fat yield and dairy efficiency. Highlights DCGF can replace AH to improve nutrient digestibility and milk yield. Improvements in nutrient digestibility when DCGF replaces AH potentially reduce total waste production of dairy cows. Completely replacing AH with DCGF in low forage diets reduces milk fat yield due to change in ruminal fermentation.

Astragalus root extract improved average daily gain, immunity, antioxidant status and ruminal microbiota of early weaned yak calves.

Early weaning in yak calves is being attempted to improve yak reproduction rate. However, this has to be done with caution because of the high mortality rate of calves due to the lack of nutrients and the harsh environmental conditions. Twenty-four weaned male yak calves were used in a 60 day feeding trial in which astragalus root extract (ARE) was supplemented. They were assigned randomly to one of four dietary treatments (n = six per treatment) that differed in ARE level: 0 g kg-1 (control), ARE0 ; 20 g kg-1 , ARE20 ; 50 g kg-1 , ARE50; and 80 g kg-1 dry matter intake (DMI), ARE80 . Final bodyweight and average daily gain (ADG) were significantly higher and the DMI/ADG ratio was significantly lower in calves with ARE supplementation than control (ARE0 ) calves. Ruminal concentrations of acetate and propionate and serum concentration of superoxide dismutase in ARE80 calves were higher than in the other groups and serum concentration of insulin was higher in ARE80 calves than in ARE20 calves. Serum immunoglobulin G (IgG) and interleukin-2 (IL-2) concentrations in ARE-fed calves were higher than in controls. Serum tumor necrosis factor (TNF-α) concentration was higher in ARE50 and ARE80 groups than ARE0 calves and serum interleukin-6 (IL-6) concentration was higher in ARE80 than in ARE0 calves. Serum immunoglobulin A (IgA), IgG and immunoglobulin M (IgM) concentrations increased with age in ARE-fed calves. ARE supplementation increased the abundance of fiber degrading bacteria. ARE at a dosage of 5% to 8% DMI can be supplemented to early weaned yak calves to improve growth performance, antioxidant capacity and immunity. © 2020 Society of Chemical Industry.

Effect of replacing conventional feeds with tropical agricultural by‐products on the growth performance, nutrient digestibility and ruminal microbiota of water buffaloes

This study investigated the effect of replacing corn grain, soybean meal and wheat bran with tropical agricultural by-products, such as palm kernel cake (PKC), cassava residue and dried distiller's grain with solubles (DDGS), on the dry matter intake (DMI), growth performance, apparent nutrient digestibility, ruminal short-chain fatty acids (SCFA) and ruminal microbial communities of water buffaloes. Thirty healthy 15-month-old crossbred water buffaloes with a similar initial body weight of 353.1±23.7kg were randomly allocated into three dietary experimental groups, and they were fed with same forage but three different concentrates for 50days fattening. The dietary treatments were as following: typical concentrate (TC, 65% corn+15% wheat bran+15% soybean meal), partial replacement concentrate Ⅰ (PRC I, 50% corn+22.5% corn gluten+22.5% PKC) and partial replacement concentrate Ⅱ (PRC II, 50% corn+22.5% cassava residue+22.5% DDGS). The results showed that the average daily gain of the PRC II group was the highest, and the DMI, acid detergent fibre digestibility and neutral detergent fibre digestibility value of the three groups were different and in the following order: PRC II group>TC group>PRC I group. The crude protein digestibility of PRC II was higher than that of the TC and PRC I groups (p<.05). The ruminal concentrations of total SCFA, acetate, propionate and butyrate of TC group were higher than the other two groups (p<.05). The PRC I group had the highest Bacteroidetes-to-Firmicutes ratio (B/F) and relative abundance of the genus Prevotella, while the PRC II group had the lowest B/F and relative abundance of Prevotella. In conclusion, using PKC and corn gluten to completely replace common feed ingredients in the buffalo concentrate ration decreased, while using cassava residue and DDGS increased animal growth performance, mainly due to the different combination influenced nutrient digestibility and ruminal microbial community composition was shifted.

Combining Crude Glycerin with Chitosan Can Manipulate In Vitro Ruminal Efficiency and Inhibit Methane Synthesis.

Simple SummaryMethane (CH4) inhibition approaches in ruminants are considered to provide economic benefits and reduce global greenhouse gases. The inclusion of crude glycerin at 21% in to total mixed ration (TMR) diets with chitosan supplementation at 2% enhanced ruminal propionate concentration and reduced methane production without causing any detrimental effect on the gas kinetics or nutrient digestibility.It was hypothesized that the combination of glycerin and chitosan improves ruminal fermentation efficiency via an enhanced propionate (C3) and reduces in vitro CH4 production. This was explored through in vitro gas production with substrates containing crude glycerin, which replaced cassava chips in the studied ration. The experimental design was organized following a 3 × 3 factorial in completely randomized design and the arrangement of treatments were different levels of crude glycerin supplementations 0, 10.5, and 21% of total mixed ration (TMR) and chitosan levels were added at 0, 1, and 2% dry matter (DM) of substrate. Then, 0.5 g of TMR substrates were added into 40 mL bottles, together with respective doses of chitosan and then incubated at 39 °C. The dietary treatments were performed in three replicates within the incubation, and incubations were repeated on three separate days (runs). No interactions were found between crude glycerin and chitosan doses in terms of theoretical maximum of asymptotic gas production (b), rate of gas production (c), the discrete lag time prior to gas production (L), or the cumulative gas production at 96 h of incubation (p > 0.05). Cumulative gas production at 96 h of incubation was similar among the doses of crude glycerin and levels of chitosan, which ranged from 64.27 to 69.66 mL/g DM basis of substrate (p > 0.05). The concentration of ruminal NH3-N after 2 and 4 h of incubation ranged from 14.61 to 17.10 mg/dL and did not change with the addition of crude glycerin with chitosan (p > 0.05). The concentration of CH4 after 2 h of incubation did not change among treatments (p > 0.05), whereas after 4 h of incubation, CH4 synthesis was significantly reduced by enhancing doses of crude glycerin and chitosan (p < 0.05). The combination of 21% of crude glycerin in TMR with 2% chitosan depressed CH4 production as much as 53.67% when compared to the non-supplemented group. No significant crude glycerin and chitosan interaction effect was detected for in vitro digestibility of nutrients after incubation for 12 and 24 h using the in vitro gas production technique (p > 0.05). In addition, no significant changes (p > 0.05) were observed in total volatile fatty acids, acetate (C2) or butyrate content among treatments and between the main effects of crude glycerin with chitosan. At 4 h of incubation, ruminal C3 content and the C2 to C3 ratio changed significantly when crude glycerin and chitosan was added (p < 0.05). The 21% crude glycerin incorporate into TMR, in combination with 2% additional chitosan, increased C3 content by 26.41%, whereas the ratio of C2 to C3 was reduced by 31% when compared to the control group. Propionate concentration increased by 11.75% when increasing levels of chitosan at 2% of substrate, whereas the C2 to C3 ratio decreased by 13.99% compared to the 0% chitosan group. The inclusion of crude glycerin at 21% in TMR diets with chitosan supplementation at 2% enhanced ruminal propionate concentration and reduced methane production without causing any detrimental effect on the gas kinetics or nutrient digestibility.