Differences in rumen fermentation characteristics between low‐yield and high‐yield dairy cows in early lactation

Relationship between rumen fermentation parameters, blood biochemical profiles and milk production traits in different yielding dairy cows during early lactation was investigated. Twelve dairy cows were divided into two groups based on their milk yield, that is low‐yield (LY) and high‐yield (HY) groups. Rumen fluid and blood were collected at 3 weeks prepartum and 4, 8 and 12 weeks postpartum. Results showed that proportions of acetate, propionate to total short chain fatty acids and acetate : propionate ratio were changed (P < 0.05) in both groups during the peripartum period, whereas butyrate and acetate : butyrate ratio were only altered in the HY group. Blood cholesterol, beta‐hydroxybutyric acid (BHBA) and glutamic oxaloacetic transaminase in the HY group were higher (P < 0.01) than those in the LY group. Principal component analysis revealed that milk yield and milk compositions were differently clustered between groups. These parameters showed similar direction with dry matter intake in the HY group and adverse direction in the LY group. Linear regression analysis indicated that butyrate was positively correlated with BHBA (P < 0.05) in the HY group. This study suggests that cows in the HY group seem to accommodate appropriately to negative energy balance in early lactation through rumen fermentation.     

Growth of rumen papillae in weaned calves is associated with lower expression of insulin‐like growth factor‐binding proteins 2, 3, and 6

This study aimed to characterize the relationship between the growth of rumen papillae in calves and the mRNA expression of insulin‐like growth factor‐binding proteins (IGFBPs) in the rumen papillae. The length of rumen papillae, the mRNA expression of IGFBPs in rumen papillae by quantitative real‐time PCR, and the presence of insulin‐like growth factors I and II (IGF‐I and II) by immunohistochemistry (IHC) were analyzed in nine Holstein calves divided into three groups: suckling (2 weeks, n = 3), milk‐continued (8 weeks, n = 3), and weaned (8 weeks, n = 3). The length of rumen papillae was greater (p < 0.01) in weaned calves than in suckling and milk‐continued calves, whereas the expressions of IGFBP2, IGFBP3, and IGFBP6 genes were lower (p < 0.05) in the rumen papillae of weaned calves than in milk‐continued calves. Thus, rumen papillae length and IGFBP2, 3, and 6 expressions were negatively correlated. The IHC analysis showed that IGF‐I and IGF‐II were present in the rumen epithelium of calves. These results suggested that the growth of rumen papillae after weaning is associated with the induction of IGFs by the low levels of IGFBP2, IGFBP3, and IGFBP6.     

Effects of butyrate supplementation in antibiotic‐free milk replacer and starter on growth performance in suckling calves

The aim of this study was to evaluate butyrate supplementation of antibiotic‐free milk replacer and starter on growth performance in male Holstein calves. Twenty‐nine calves were divided into two groups. Group C (n = 13) was fed antibiotic‐free milk replacer without supplementation, and Group B (n = 16) was fed antibiotic‐free milk replacer supplemented with butyrate (1.6 % DM of Gustor BP70^®). Starter in Group B contained 0.3 % DM of Gustor BP70^®. The intake of milk replacer was lower in group B than in C (p = 0.07 for the treatment x week interaction). Body weight (BW) and heart girth (HG) in group B was higher than in C during the experimental period (p = 0.07 and 0.01 for the treatment × week interaction, respectively). The duration of the weaning period in group B was shorter than in group C (p = 0.02). β‐hydroxybutyrate (BHBA) was higher in group B than in C (p = 0.04). Insulin like growth factor‐1 (IGF‐1) concentrations tended to be higher in group B than in C (p = 0.07 for treatment × week interaction). Our results show that butyrate supplementation in antibiotic‐free milk replacer and starter exerted positive effects on growth performance in suckling calves.     

Investigation into the causes of aspirin resistance in healthy dogs

Antiplatelet effects of acetylsalicylic acid (ASA, aspirin) may be poor in some individuals. Additionally, no method exists for predicting poor ASA response (resistance) in individual dogs. This study's main objective was to determine whether poor ASA response results from pharmacodynamic or pharmacokinetic causes. ASA concentrations causing 50% inhibition of platelet aggregation (in vitro IC50) were determined using whole blood collected from 21 drug‐free healthy dogs to evaluate intrinsic sensitivity of platelets to ASA. Dogs were then administered ASA at 4 mg/kg once orally. Percent decrease in platelet aggregation from baseline, and plasma ASA and salicylic acid (SA) concentrations (expressed as AUC values) were measured for up to 3 hr. By 3 hr, 13/21 (62%) dogs showed >50% aggregation inhibition, while 8/21 (38%) dogs showed <50% inhibition. Aggregation inhibition values were negatively correlated with in vitro IC50 values (Rs = ?0.49; p = 0.028) and positively correlated with ASA concentrations (Rs = 0.48; p = 0.03). Furthermore, ASA concentrations were strongly negatively correlated (Rs = ?0.88; p < 0.001) with SA/ASA concentration ratios, an index of ASA metabolism to SA by esterase enzymes. Multiple linear regression analysis indicated that 59% (p < 0.001) of interindividual variability in aggregation inhibition was explained by in vitro IC50 values (29% of variability) and ASA concentrations (29% of variability). Consequently, poor in vivo ASA response in these dogs resulted from both pharmacodynamic (decreased platelet sensitivity) and pharmacokinetic (lower ASA concentrations) causes. Lower ASA concentrations may be explained by reduced bioavailability associated with higher esterase activities.     

Total tract nutrient digestion and milk fatty acid profile of dairy cows fed diets containing different levels of whole raw soya beans

Whole oilseeds such as soya beans have been utilized in dairy rations to supply additional fat and protein. However, antinutritional components contained in soya beans, such as trypsin inhibitors and haemagglutinins (lectins) may alter digestibility of nutrients and consequently affect animal performance. The objective of the present experiment was to quantify the effect of different levels of whole raw soya beans in diets of dairy cows on nutrient intake, total tract digestion, nutrient balances and milk yield and composition. Sixteen mid to late‐lactation cows (228 ± 20 days in milk; mean ± SD) were used in four replicated 4 × 4 Latin square design experiment with 21‐d periods. Cows were assigned to each square according to milk yield and DIM. The animals were randomly allocated to treatments: control (without soya beans addition; CO), WS9, WS18 and WS27, with addition of 9%, 18% and 27% of whole raw soya bean in diet on a dry matter (DM) basis respectively. All diets contained identical forage and concentrate components and consisted of maize silage and concentrate based on ground corn and soya beans at a ratio of 60:40. There were no differences in OM, CP, NDF and NE_L intakes (kg/day and MJ/day) among the treatments (p > 0.05). However, DM and NFC intakes were negatively affected (p = 0.04 and p < 0.01, respectively) and ether extract (EE) intake was positively affected (p < 0.01). Total tract digestion increased linearly with whole raw soya beans for EE (p < 0.01) and NDF (p = 0.01). The excretion (kg/day) of digested soya beans grains increased linearly according to addition of whole raw soya beans. However, the nutritive characteristics of excreted grains were not altered. Milk (kg), milk lactose (kg) and protein (kg) yield decreased linearly (p < 0.01, p < 0.01 and p = 0.04, respectively) milk fat content (%) increased linearly (p < 0.01) with whole raw soya beans inclusion. Increasing addition of whole raw soya beans affected milk fatty acid profile with a linear decrease of cis‐9‐trans 11CLA and total saturated FA; and linear increase of total unsaturated and C_18:3 FA. Energy balance was positively affected (p = 0.03) by whole raw soya beans as well as efficiency of NEL milk/DE intake (p = 0.02). Nitrogen balance and microbial protein synthesis were not affected by whole raw soya beans. Increasing doses of whole raw soya beans decreased dry matter intake and milk yield, however, led to an increase of unsaturated acids in milk and higher milk fat concentration.     

Effect of live yeast (Saccharomyces cerevisiae) supplementation on rumen fermentation and metabolic profile of dairy cows in early lactation

The study evaluated dietary supplementation with live yeast (LY) Saccharomyces cerevisiae (CNCM I‐4407, 10¹⁰ CFU/g, Actisaf; Phileo Lesaffre Animal Care, France) on rumen fermentation and serum metabolic profile in lactating dairy cows. Fifty Holstein cows received a total mixed ration with (Live Yeast Diet, LYD, n = 25) or without (Control Diet, CD, n = 25) 5 × 10¹⁰ CFU/cow/day of LY from 3 to 19 weeks of lactation. Rumen fermentation and serum metabolic profile were measured in eight cows per treatment at 3, 7, 11, 15, 19 weeks post‐partum. LYD showed an increased daily milk yield (+4%) over CD (p < 0.05). Mean rumen pH at 4 hr after morning meal was higher in LYD (6.59) than CD (6.32) (p < 0.01). Total volatile fatty acids (VFA) and acetate molar proportion were higher in LYD (114.24 mM; 25.04%) than CD (106.47 mM; 24.73%) (p < 0.05). Propionate and butyrate molar proportions, acetate to propionate ratio, ammonia levels did not differ between LYD and CD. Ruminal lactate was lower in LYD than CD (9.3 vs. 16.4 mM) (p < 0.001), with a 53% decrease in LYD. During peak lactation, LYD had lower serum NEFA (p < 0.05, 0.40 vs. 0.48 mM) and BHBA (p < 0.01, 0.47 vs. 0.58 mM) than CD, lower liver enzyme activities (AST 1.39 vs. 1.54 ukat/L) (p < 0.05). Serum glucose was higher in LYD at peak lactation (3.22 vs. 3.12 mM, and 3.32 vs. 3.16 mM respectively) (p < 0.05). The results confirmed a reducing effect of LY on lactate accumulation in rumen fluid, associated with an increase in rumen pH. Lower serum levels of lipomobilization markers, liver enzyme activities and higher glucose levels may suggest that live yeast slightly mitigated negative energy balance and had a certain liver protective effect.     

Effect of wood kraft pulp feed on digestibility,ruminal characteristics,and milk production performance in lactating dairy cows

The effect of wood kraft pulp (KP) feed on dietary digestibility, ruminal fluid pH, rumen fermentation characteristics, and milk production performance in lactating dairy cows was examined. Four lactating dairy cows were used for the feeding experiment by the cross‐over design. The control group and KP group were set up as treatments. The control group was fed total mixed ration (TMR) (40% roughage and 60% concentrate) and the KP group was fed TMR containing 12% KP that replaced half of the rolled corn in the control diet. The dry matter intake, digestibility of the feed components, and milk yield were not significantly different between control group and KP group. The number of times that the ruminal fluid pH was below 6.1 tended to decrease in the KP group compared to the control group (p < 0.10). The acetic acid ratio in the ruminal fluid of the KP group increased compared to the control group (p < 0.05) and the propionic acid ratio in the ruminal fluid of the KP group decreased compared to the control group (p < 0.05). The acetate:propionate acid ratio was increased in the KP group compared with the control group (p < 0.05). Lipopolysaccharide levels in the ruminal fluid of the KP group tended to decrease compared to the control group (p < 0.10). Based on these results, it was indicated that the use of KP feed for lactating dairy cows induced the same rumen fermentation characteristics as those in cows given a large amount of roughage without depressing milk productivity. Therefore, KP could be a valuable feed resource substitute for grains, which would also reduce the risk for subacute rumen acidosis.     

Effects of incremental amounts of fish oil on trans fatty acids and Butyrivibrio bacteria in continuous culture fermenters

Previous studies have shown that adding fish oil (FO) to ruminant animal diets increased vaccenic acid (VA; t11 C18:1) accumulation in the rumen. Therefore, the objective of this study was to evaluate the effect of dietary FO amounts on selected strains of rumen bacteria involved in biohydrogenation. A single‐flow continuous culture system consisting of four fermenters was used in a 4 × 4 Latin square design with four 9 days consecutive periods. Treatment diets were as follows: (i) control diet (53:47 forage to concentrate; CON), (ii) control plus FO at 0.5% (DM basis; FOL), (iii) control plus FO at 2% (DM basis; FOM) and (iv) control plus FO at 3.5% (DM basis; FOH). Fermenters were fed treatment diets three times daily at 120 g/day. Samples were collected from each fermenter on day 9 of each period at 1.5, 3 and 6 h post‐morning feeding and then composited into one sample per fermenter. Increasing dietary FO amounts resulted in a linear decrease in acetate and isobutyrate concentrations and a linear decrease in acetate‐to‐propionate ratio. Propionate, butyrate, valerate and isovalerate concentrations were not affected by FO supplementation. Concentrations of C18:0 in fermenters linearly decreased, while concentrations of t10 C18:1 and VA linearly increased as dietary FO amounts increased. The concentrations of c9t11 and t10c12 conjugated linoleic acid were not affected by FO supplementation. The DNA abundance for Butyrivibrio fibrisolvens, Butyrivibrio vaccenic acid subgroup, Butyrivibrio stearic acid subgroup and Butyrivibrio proteoclasticus linearly decreased as dietary FO amounts increased. In conclusion, FO effects on trans fatty acid accumulation in the rumen may be explained in part by FO influence on Butyrivibrio group.     

Carcass tissue composition in light lambs: Influence of feeding system and prediction equations

Fourty-eight Churra Tensina single male lambs were used to evaluate the effect of different feeding systems on carcass composition and predict the carcass tissue composition from joint composition and carcass measurements. Four treatments were studied: GR, unweaned lambs continuously grazing with ewes; GR + S, the same as the previous group, but lambs had free access to concentrate; DRL-GRE, lambs remained indoors with free access to concentrate and ewes grazed for 8 h/day, thereafter remaining with lambs; and DRL, lambs and ewes were kept in confinement, they had free access to concentrate and dry unifeed respectively. In the DRL-GRE and DRL groups lambs were weaned when 45 days old. Lambs were slaughtered at 22–24 kg live weight. Commercial joints from the half left carcass were obtained, recorded and dissected to determine carcass tissue composition.The feeding system had an effect on the proportion of the carcass tissue composition. GR treatment showed higher muscle (M) (p < 0.05) and bone (B) (p < 0.001) percentages, and a lower total fat (F) percentage (p < 0.001) than the rest of treatments. Hence it revealed higher M/F (p < 0.01) and lower M/B (p < 0.05) and subcutaneous fat/intermuscular fat ratios (SF/IF; p < 0.001). Carcass composition predictions were more accurate for grams than for percentages. In predictions from joint composition, pelvic limb was the most accurate joint for grams (R² = 0.84, R² = 0.68, and R² = 0.77 for muscle, bone, and fat, respectively) as well as for percentage (R² = 0.65, R² = 0.56, and R² = 0.73 for muscle, bone, and fat, respectively). Predictions from carcass measurements were greater in muscle and fat grams (R² = 0.87 and R² = 0.86 for muscle and fat, respectively) than in percentage (R² = 0.58 and R² = 0.73 for muscle and fat, respectively). Equations to predict carcass tissue that include carcass measurements are a simple method to assess accurately saleable muscle yield from different lamb feeding systems without involving carcass damage.     

Effects of substituting kraft pulp with corn silage on dry matter intake,ruminal mat formation,rumen fermentation,and rumination activity in non‐lactating cows

The present study examined the effects of substituting kraft pulp (KP) with corn silage (CS) on dry matter intake (DMI), ruminal mat and rumen fermentation characteristics, and rumination. Four non‐lactating, rumen‐cannulated Holstein cows were fed a CS diet comprising 36% grass silage (GS) and 64% CS or a KP diet comprising 36% GS, 57% KP, and 7% soybean meal. DMI was significantly lower in cows fed the KP diet than in those fed the CS diet (p < 0.05), whereas rumination time did not significantly differ between the treatments. Dry matter content in the rumen immediately before and 3 h after feeding was significantly higher in cows fed the KP diet than in those fed the CS diet (p < 0.05). The consistency and thickness of the ruminal mat did not significantly differ between the treatments. The ruminal mean retention time of feed particles tended to be longer in cows fed the KP diet than in those fed the CS diet (p < 0.10). The ruminal digestion rate of KP was comparable to that of GS and CS. Because ruminal mat was formed and rumination was stimulated, KP was considered to have the equivalent physical effectiveness as CS.     

Plasma cholesterol levels and short-term adaptations of metabolism and milk production during feed restriction in early lactating dairy cows on pasture

Low plasma total cholesterol (TC) concentrations are characteristic during the negative energy balance in early lactating dairy cows. The objective was to investigate short-term effects of different TC concentrations during an aggravated energy deficiency through a 1-week concentrate withdrawal on adaptations of metabolism and milk production. Multiparous Holstein cows (n = 15) were investigated during 3 week beginning at 24 ± 7 DIM (mean ± SD). Cows were kept on pasture and received additional concentrate in experimental week 1 and 3, while in week 2, concentrate was withdrawn. Blood was sampled once and milk twice daily. Based on their average TC concentration during week 1 (prior to concentrate withdrawal), cows were retrospectively assigned into a high (H-Chol; n = 8, TC ≥ 3.36 mmol/L) and a low TC groups (L-Chol; n = 7, TC < 3.36 mmol/L). Concentrations of phospholipids and lipoproteins were higher in H-Chol compared to L-Chol throughout the study (p < 0.05). During concentrate withdrawal, milk yield, glucose and insulin concentrations decreased similarly in both groups, while milk fat, milk acetone and plasma BHB were higher in H-Chol compared to L-Chol (p < 0.05). Compared to initial values, plasma NEFA, TAG and VLDL increased in both groups within 2 days after concentrate withdrawal (p < 0.05). Concentrations of NEFA during week 2 were greater in L-Chol compared to H-Chol (p < 0.05). Despite reintroduction of concentrate, milk yield in H-Chol remained lower for two more days compared to week 1 (p < .05), whereas milk yield recovered immediately in L-Chol. Activity of aspartate aminotransferase was higher in H-Chol compared to L-Chol in week 2 (p < 0.05). Greater plasma TC concentrations were associated with a reduced increase of NEFA. Further research is warranted if TC concentrations are related to adipose tissue mobilization and fatty acid turnover.     

Dietary supplementation with inulin improves lactation performance and serum lipids by regulating the rumen microbiome and metabolome in dairy cows

This study investigated the effects of inulin on rumen fermentation parameters, ruminal microbiome and metabolites, as well as lactation performance and serum indexes in dairy cows. Sixteen Holstein dairy cows with similar body conditions were randomly divided into 2 groups (n = 8 per group), with inulin addition at 0 and 200 g/d per cow. The experiment lasted for 6 weeks, including a 1-week adaptation period and a 5-week treatment period. At the end of the experimental period, the milk, serum and rumen fluid were sampled and analyzed. The microbiome and metabolome in the rumen fluid were analyzed via 16S rRNA sequencing and untargeted metabolomics, respectively. The results showed that supplementation with inulin (200 g/d per cow) increased the milk yield (P = 0.001), milk protein (P = 0.032), lactose rate (P = 0.004) and proportion of saturated fatty acids (SFA) in milk (P < 0.001), but decreased the proportion of unsaturated fatty acids (USFA) (P = 0.041). Rumen pH (P = 0.040) and the concentration of NH₃–N (P = 0.024) were decreased; however, acetate (P < 0.001), propionate (P = 0.003), butyrate (P < 0.001) and lactic acid (LA) (P = 0.043) were increased. The total cholesterol (TC) (P = 0.008) and triglycerides (TG) (P = 0.01) in serum were also reduced. Additionally, inulin addition elevated the relative abundance of several beneficial symbiotic and short-chain fatty acid (SCFA)-producing bacteria, such as Muribaculaceae (false discovery rate [FDR]-adjusted P < 0.01), Acetitomaculum (FDR-adjusted P = 0.043), and Butyrivibrio (FDR-adjusted P = 0.036), while elevating the levels of L-lysine (FDR-adjusted P = 4.24 × 10⁻³), L-proline (FDR-adjusted P = 0.0158), and L-phenylalanine (FDR-adjusted P = 0.027). In contrast, several pathogens and ruminal bacteria abundant in high-fat diets, such as Escherichia-Shigella (FDR-adjusted P = 0.022), Erysipelotrichaceae__UCG-004 (FDR-adjusted P < 0.01) and RF39 (FDR-adjusted P = 0.042) were decreased along with the reduction of lysophosphatidylcholine (LysoPC) (18:1 (9Z)) (FDR-adjusted P = 1.03 × 10⁻³), LysoPC (16:0) (FDR-adjusted P = 0.0108), LysoPC (18:2 (9Z, 12Z)) (FDR-adjusted P = 1.65 × 10⁻³) and 8-methylnonenoate. In conclusion, dietary inulin supplementation could increase the relative abundance of commensal microbiota and SCFA-producing bacteria, upregulate amino acidmetabolism and downregulate lipid metabolism in the rumen of dairy cows, which might further improve lactation performance and the level of serum lipids.     

Comparison of feed intake,digestion and rumen function among domestic ruminant species grazing in upland vegetation communities

This study aimed to compare feed intake, digestion, rumen fermentation parameters and bacterial community of 5 beef cows, 12 crossed ewes and 12 goats grazing together in spring–early summer on heather–gorse vegetation communities with an adjacent area of improved pasture. Organic matter intake (OMI) and digestibility (OMD) were estimated using alkane markers. Ruminal fluid samples were collected for measuring fermentation parameters, and studying the bacterial community using terminal restriction fragment length polymorphism (T‐RFLP). Spot samples of urine were taken to determine purine derivative (PD) and creatinine concentrations to estimate microbial protein synthesis in the rumen. Herbaceous species were the main dietary component in all animal species. Cattle had higher (p < 0.05) daily OMI (g/kg LW^0.75) and OMD, whereas sheep and goats showed similar values. The highest ammonia concentration was observed in sheep. Total VFA, acetate and butyrate concentrations were not influenced by animal species, while propionate concentrations in goats were 1.8 times lower (p < 0.05) than in sheep. Acetate:propionate ratio was greater (p < 0.05) in goats, whereas cattle excreted more allantoin (p < 0.05). Estimated supply of microbial N was higher in cows (p < 0.01), whereas the efficiency of microbial protein synthesis was lower (p < 0.01) in this animal species. Hierarchical clustering analysis indicated a clear effect of animal species on rumen bacterial structure. Differences among animal species were also observed in the relative frequency of several T‐RFs. Certain T‐RFs compatible with Lachnospiraceae, Proteobacteria and Clostridiales species were not found in goats, while these animals showed high relative frequencies of some fragments compatible with the Ruminococcaceae family that were not detected in sheep and cattle. Results suggest a close relationship between animals’ grazing behaviour and rumen bacterial structure and its function. Goats seem to show a greater specialization of their microbial populations to deal with the greater fibrous and tannin content of their diet.     

Effect of NDF/undegradable crude protein ratio on in vivo digestibility, particle passage rate in riverine buffaloes compared with sheep

In vivo digestibility (eight animals) and solid particles passage rate measured by faecal Cr (four animals fistulated at the rumen) were determined on riverine buffalo bulls and Delle Langhe rams, given four diets at maintenance level (50 g/kg M^0.75 per day of dry matter), according to a Latin square design, composed of a factorial combination of high and low NDF and of high and low protein undegradability. The diets were: L-30 = low NDF (530.0 g/kg DM), low undegradability of protein (29.6%, CP = 138.0 g/kg DM); L-40 = low NDF (537.0 g/kg DM), high undegradability of protein (41.0%, CP = 139.0 g/kg DM); H-30 = high NDF (583.0 g/kg DM), low undegradability of protein (28.3%, CP = 128.0 g/kg DM); H-40 = high NDF (NDF = 580.0 g/kg DM), high undegradability of protein (40.0%, CP = 128.0 g/kg DM). The digestibility of organic matter (66.68% vs. 64.32%, P < 0.05) and of the other analytical fractions (NSC, NDF, cellulose and hemicelluloses) was significantly higher in buffaloes with the exception of that of crude protein which was similar for the two species. Considering the diets within the species, the increased undegradable protein in the small intestine produces different effects: in the buffalo, it does not positively influence the digestibility of NSC but does increase that of cellulose, on the other hand in sheep it influences the digestibility of NSC. The post-ruminal digestibility of the undegraded protein, both in buffalo and sheep, is higher than that from protein of microbial origin. The passage rate of the marker of the solid particles, through the first compartment, k₁ (2.86% h^− 1 and 2.54% h^− 1 for the buffalo and the sheep) and through the entire intestinal tract, MRT (57.50 and 58.88 h for the buffalo and the sheep) does not show significant differences in the two species. The passage rate of the marker of the solid particles in buffalo rumen, at variance with the structural carbohydrates of the diet, is more variable compared with that of the sheep.     

Low ambient temperature elevates plasma triiodothyronine concentrations while reducing digesta mean retention time and methane yield in sheep

Ruminant methane yield (MY) is positively correlated with mean retention time (MRT) of digesta. The hormone triiodothyronine (T₃), which is negatively correlated with ambient temperature, is known to influence MRT. It was hypothesised that exposing sheep to low ambient temperatures would increase plasma T₃ concentration and decrease MRT of digesta within the rumen of sheep, resulting in a reduction of MY. To test this hypothesis, six Merino sheep were exposed to two different ambient temperatures (cold treatment, 9 ± 1 °C; warm control 26 ± 1 °C). The effects on MY, digesta MRT, plasma T₃ concentration, CO₂ production, DM intake, DM digestibility, change in body weight (BW), rumen volatile fatty acid (VFA) concentrations, estimated microbial protein output, protozoa abundance, wool growth, water intake, urine output and rectal temperature were studied. Cold treatment resulted in a reduction in MY (p < 0.01); digesta MRT in rumen (p < 0.01), hindgut (p = 0.01) and total digestive tract (p < 0.01); protozoa abundance (p < 0.05); and water intake (p < 0.001). Exposure to cold temperature increased plasma T₃ concentration (p < 0.05), CO₂ production (p = 0.01), total VFA concentrations (p = 0.03) and estimated microbial output from the rumen (p = 0.03). The rate of wool growth increased (p < 0.01) due to cold treatment, but DM intake, DM digestibility and BW change were not affected. The results suggest that exposure of sheep to cold ambient temperatures reduces digesta retention time in the gastrointestinal tract, leading to a reduction in enteric methane yield. Further research is warranted to determine whether T₃ could be used as an indirect selection tool for genetic selection of low enteric methane‐producing ruminants.     

Feed and water deprivation has a negative but transient effect on the rumen kinetics of Bos indicus steers

The effects on rumen kinetics after feed and water had been deprived for 72 hr were studied using four fistulated Bos indicus steers. The animals were assigned in a 2 × 4 crossover design with two treatments: feed and water ad libitum (control) and no feed and water for 72 hr (deprived) with four steers per treatment over two time periods. Feed and water deprivation caused decreases in the numbers of cellulolytic bacteria (1.4 vs. 0.4 cfu × 10⁶/ml; p = .001), live (23.7 vs. 0.8 × 10⁹/ml; p = .001), dead (12.7 vs. 0.5 × 10⁹/ml; p = .001) and total bacterial counts (36.4 vs. 1.4 × 10⁹/ml; p = .001) at day 0, compared with the control treatment. However, the deprived group had greater numbers of cellulolytic bacteria (2.7 vs. 50.1 cfu × 10⁶/ml; p = .001), live (18.3 vs. 42.2 × 10⁹/ml; p = .001), dead (6. 5 vs. 19.1 × 10⁹/ml; p = .001) and total bacterial counts (24.8 vs. 61.3 × 10⁹/ml; p = .001) from rumen fluid on day 4, compared with the control treatment. The numbers of protozoa in rumen fluid from the deprived group were less than (551.2 vs. 2.4 × 10³/ml; p = .001) the control group on day 0. However, the deprived treatment had fewer protozoa in rumen fluid than the control treatment on day 4 (p = .001) and day 9 (p = .001). Volatile fatty acids and in vitro gas production as functional measurements of rumen fluid followed the same trend as the bacterial and protozoa populations. These results indicate that feed and water deprivation would have a negative but transient effect on the rumen kinetics of Bos indicus steers.     

Mitigating rumen methane and enhancing fermentation using rambutan fruit peel powder and urea in lactating dairy cows

The experiment was designed to study the use of rambutan (Nephelium lappaceum) fruit peel powder (RP) with urea (U) supplementation on rumen fermentation, digestibility, methane (CH₄) production, milk production and composition in lactating dairy cows. Four Holstein crossbred lactating dairy cows, with starting liveweight of 450 ± 15 kg with 130 ± 10 DIM (days-in-milk), were randomly allocated to respective treatments: without supplementation (control; T1), supplementation of urea (U) at 90 g/hd/day (T2), supplementation of RP at 450 g/hd/day (T3) and supplementation of RPU (RP at 450 g/hd/day and U 90 g/hd/day) (T4), respectively, using a 4 × 4 Latin square design. The results showed that the U, RP and RPU supplementation did not change feed intakes (p > 0.05) and digestibilities of DM and OM were similar. However, digestibilities of CP and NDF were increased in the U and RPU groups (p < 0.05). Acetate production was decreased, while propionate production was dramatically increased (p < 0.05) in both the RP and RPU groups respectively. Notably, the ratio of C₂:C₃, protozoal population and CH₄ production was reduced in both the RP and RPU groups. In addition, nitrogen intake and nitrogen excretion were significantly higher while nitrogen retention was increased in the U and RPU groups. Allantoin excretion and absorption, microbial protein synthesis and efficiency of microbial N supply were increased in the U and RPU supplementation groups (p < 0.05). Furthermore, milk yield, milk fat and total solids were significantly enhanced in the U and RPU groups (p < 0.05). Moreover, the 3.5% FCM was increased (p < 0.05) while milk protein, lactose, solids-not-fat and milk urea nitrogen were not altered (p > 0.05). Supplementation of either U or RPU significantly improved fibre digestibilities, rumen fermentation, microbial protein synthesis, reduced protozoal population, mitigated CH₄ production and enhanced milk yield and milk composition.     

Glycerine as a feed supplement for beef and dairy cattle: A meta-analysis on performance,rumen fermentation,blood metabolites and product characteristics

This study aimed to comprehensively evaluate the effects of glycerine supplementation at various concentrations on performance, rumen fermentation, blood metabolites and product characteristics of beef and dairy cattle in vivo by using a quantitative meta-analysis approach. Meta-analysis was performed by integrating a total of 52 studies from 39 articles and 182 treatments into a database. Data were constructed into an intact database and did not distinguish between beef and dairy cattle, except for the parameters of production performance and product characteristics. Data summarized were analysed by using a statistical meta-analysis that employed a fixed effect of glycerine supplementation level and a random effect of various studies for both beef and dairy cattle. Significance of an effect was stated at the probability level of p < .05, and p < .1 was considered as a tendency of significant. Results revealed that there was a linear decrease on dry matter intake (p < .01) and daily gain (p < .05) of beef cattle with the increasing levels of glycerine supplementation. Glycerine supplementation did not decrease milk production of lactating dairy cows. Molar proportion of acetate in the rumen was decreased (p < .001), whereas propionate and butyrate proportions were increased (both at p < .001) by glycerine supplementation. Generally, glycerine did not change nutrient digestibility except that it reduced fibre digestibility (p < .001). Glycerine supplementation linearly lowered triglyceride and NEFA concentrations (both at p < .05) in the blood serum, but not other blood metabolites. Glycerine tended to linearly increase (p < .1) carcass percentage in beef cattle. Increasing dietary glycerine levels decreased milk fat (p < .01) but elevated milk protein (p < .001). Glycerine tended to increase milk lactose (p < .1) by following a quadratic pattern. The proportion of MUFA was increased quadratically by glycerine supplementation (p < .05), whereas glycerine tended to decrease SFA by following a quadratic pattern (p < .1).     

Effect of Megasphaera elsdenii NCIMB 41125 dosing on rumen development,volatile fatty acid production and blood β‐hydroxybutyrate in neonatal dairy calves

Thirty calves were randomly assigned to two treatments and fed until weaning [42 days (d) of age]. Treatments were a control group (n = 15), which did not receive Megasphaera elsdenii (Me0) and a M. elsdenii group, which received a 50‐ml oral dose of M. elsdenii NCIMB 41125 (10⁸ CFU/ml) at day 14 day of age (Me14). Calves were given colostrum for the first 3 day followed by limited whole milk feeding. A commercial calf starter was offered ad libitum starting at day 4 until the end of the study. Fresh water was available throughout the study. Feed intake and growth were measured. Blood samples were collected via jugular venipuncture to determine β‐hydroxybutyrate (BHBA) concentrations. Fourteen male calves (seven per group) were euthanised on day 42 and digestive tracts harvested. Reticulo‐rumen weight was determined and rumen tissue samples collected from the cranial and caudal sacs of the ventral and dorsal portions of the rumen for measurements of papillae length, papillae width and rumen wall thickness. Dosing with M. elsdenii NCIMB 41125 improved starter dry matter intake (DMI), weaning body weight (BW) and tended to improve average daily gain. Calves in Me14 group had greater plasma BHBA concentration than Me0‐calves during the last 3 weeks of the trial and had at day 42 greater reticulo‐rumen weight, papillae width and papillae density compared to Me0. No differences in rumen wall thickness or papillae length were observed between the two groups. Total volatile fatty acids, acetate and propionate production did not differ between treatments, but butyrate production was greater in Me14 than Me0. Dosing M. elsdenii NCIMB 41125 showed benefit for calves with improved feed intake and rumen development suggesting increased epithelium metabolism and improved absorption of digestive end products.