Rumen Fermentation In Dairy Cows Research Articles

Performance of Holstein dairy cows fed a diet supplemented with rosemary and ginger essential oils: milk production, milk fatty acid, and ruminal fermentation

Abstract The study determined the impact of Rosmarinus officinalis and/or Zingiberene officinalis essential oil (EO) on milk yield, composition, milk fatty acids profile, blood biochemicals, and rumen fermentation in dairy cows. Twenty-eight Holstein lactating cows were distributed into four groups using a completely randomized block design in a 70-d experiment. The control diet consisted of 13 kg of concentrate and 40 kg of fresh berseem clover per head per day, without supplementation. In the other treatments, the control diet was supplemented with 10 mL of EO per head per day, using either ginger EO (GEO treatment), rosemary (REO treatment) EO or a blend of both at a 1:1 v/v ratio (BEO treatment). Supplementation did not affect intake, milk production, or composition. Omega-n3 and omega-n5 were increased with REO (p < 0.05) compared to the control. Both REO and BEO decreased (p = 0.003) serum globulin and increased (p < 0.005) albumin to globulin ratio, high-density lipoprotein cholesterol, and total lipid. Serum total antioxidant capacity was increased (p ˂ 0.001) with the supplementation, without affecting glucose, total protein, albumin, serum cholesterol, low-density lipoprotein cholesterol, alanine aminotransferase, aspartate aminotransferase, and urea concentrations. In conclusion, supplementing Holstein dairy cows with GEO and/ or REO increased the level of omega-3 and omega-5 fatty acids while reduced saturated fatty acids in milk, without affecting feed intake, milk production or milk composition.

The effect of Phyllanthus emblica (Amla) fruit supplementation on the rumen microbiota and its correlation with rumen fermentation in dairy cows.

Medicinal plants, rich in phytochemicals like phenolic acids, flavonoids, and tannins, offer potential benefits in enhancing productivity, quality, and animal health. Amla fruit (Phyllanthus emblica) is one such plant with promising attributes. This study aimed to investigate the impact of fresh Amla fruit (FAF) supplementation on ruminal microbial composition and its correlation with rumen fermentation in lactating dairy cows. The study employed a repeated crossover design involving eight ruminally cannulated mid-lactation Holstein dairy cows. Animals received varying levels of fresh Amla fruit supplementation (0, 200, 400, and 600 g/d). When 400 g/d of FAF was added to the diet, there was a significant increase in the relative abundance of Firmicutes (p = 0.02). However, at 200 g/d, the relative abundance of ruminal Bacteroidota was higher than the 0 and 400 g/d FAF supplementation (p < 0.01). LEfSe analysis identified distinct taxa, such as Clostridia vadinBB60 in the 200 g/d group, Oscillospiraceae in the 400 g/d group, and Elusimicrobium in the 600 g/d group. Notably, the random forest species abundance statistics identified Oscillospiraceae V9D2013 as a biomarker related to milk yield. Oscillospiraceae, Bacilli RF39, norank_f Prevotellaceae, and Bifidobacterium were positively correlated with ruminal total VFA and molar proportion of propionate, while Rikenellaceae RC9 gut group and Clostridia vadinBB60 were negatively correlated. FAF supplementation affects the abundance of beneficial microbes in a dose-dependent manner, which can improve milk yield, efficiency, rumen health, desirable fatty acids, and animal health.

Exhalomics as a noninvasive method for assessing rumen fermentation in dairy cows: Can exhaled-breath metabolomics replace rumen sampling?

Previously, we used secondary electrospray ionization-mass spectrometry (SESI-MS) to investigate the diurnal patterns and signal intensities of exhaled (EX) volatile fatty acids (VFA) of dairy cows. The current study aimed to validate the potential of an exhalomics approach for evaluating rumen fermentation. The experiment was conducted in a switchback design, with 3 periods of 9 d each, including 7 d for adaptation and 2 d for sampling. Four rumen-cannulated original Swiss Brown (Braunvieh) cows were randomly assigned to 1 of 2 diet sequences (ABA or BAB): (A) low starch (LS; 6.31% starch on a dry matter basis) and (B) high starch (HS; 16.2% starch on a dry matter basis). Feeding was once per day at 0830 h. Exhalome (with the GreenFeed System), and rumen samples were collected 8 times to represent every 3 h of a day, and EX-VFA and ruminal (RM)-VFA were analyzed using SESI-MS and HPLC, respectively. Furthermore, the VFA concentration in the gas phase (HR-VFA) was predicted based on RM-VFA and Henry's Law (HR) constants. No interactions were identified between the types of diets (HS vs. LS) and the measurement methods on daily average VFA profiles (RM vs. EX or HR vs. EX), suggesting a consistent performance among the methods. Additionally, when the 3-h interval VFA data from HS and LS diets were analyzed separately, no interactions were observed between methods and time of day, indicating that the relative daily pattern of VFA molar proportions was similar regardless of the VFA measurement method used. The results revealed that the levels of acetate sharply increased immediately after feeding, trailed by an increase in the acetate:propionate ratio and a steady increase for propionate (2 h after feeding the HS diet, 4 h for LS), and butyrate. This change was more pronounced for the HS diet than the LS diet. However, there was no overall diet effect on the VFA molar proportions, although the measurement methods affected the molar proportions. Furthermore, we observed a strong positive correlation between the levels of RM and EX acetate for both diets (HS: r = 0.84; LS: r = 0.85), RM and EX propionate (r = 0.74), and RM and EX acetate:propionate ratio (r = 0.80). Both EX-VFA and RM-VFA exhibited similar responses to feeding and dietary treatments, suggesting that EX-VFA could serve as a useful proxy for characterizing RM-VFA molar proportions to evaluate rumen fermentation. Similar relationships were observed between RM-VFA and HR-VFA. In conclusion, this study underscores the potential of exhalomics as a reliable approach for assessing rumen fermentation. Moving forward, research should further explore the depth of exhalomics in ruminant studies to provide a comprehensive insight into rumen fermentation metabolites, especially across diverse dietary conditions.

Exhaled volatile fatty acids, ruminal methane emission, and their diurnal patterns in lactating dairy cows

To date, the commonly used methods to assess rumen fermentation are invasive. Exhaled breath contains hundreds of volatile organic compounds (VOC) that can reflect animal physiological processes. In the present study, for the first time, we aimed to use a noninvasive metabolomics approach based on high-resolution mass spectrometry to identify rumen fermentation parameters in dairy cows. Enteric methane (CH4) production from 7 lactating cows was measured 8 times over 3 consecutive days using the GreenFeed system (C-Lock Technology Inc.). Simultaneously, exhalome samples were collected in Tedlar gas sampling bags and analyzed offline using a secondary electrospray ionization high-resolution mass spectrometry system. In total, 1,298 features were detected, among them targeted exhaled volatile fatty acids (eVFA; i.e., acetate, propionate, butyrate), which were putatively annotated using their exact mass-to-charge ratio. The intensity of eVFA, in particular acetate, increased immediately after feeding and followed a similar pattern to that observed for ruminal CH4 production. The average total eVFA concentration was 35.5 count per second (CPS), and among the individual eVFA, acetate had the greatest concentration, averaging 21.3 CPS, followed by propionate at 11.5 CPS, and butyrate at 2.67 CPS. Further, exhaled acetate was on average the most abundant of the individual eVFA at around 59.3%, followed by 32.5 and 7.9% of the total eVFA for propionate and butyrate, respectively. This corresponds well with the previously reported proportions of these VFA in the rumen. The diurnal patterns of ruminal CH4 emission and individual eVFA were characterized using a linear mixed model with cosine function fit. The model characterized similar diurnal patterns for eVFA and ruminal CH4 and H2 production. Regarding the diurnal patterns of eVFA, the phase (time of peak) of butyrate occurred first, followed by that of acetate and propionate. Importantly, the phase of total eVFA occurred around 1 h before that of ruminal CH4. This corresponds well with existing data on the relationship between rumen VFA production and CH4 formation. Results from the present study revealed a great potential to assess the rumen fermentation of dairy cows using exhaled metabolites as a noninvasive proxy for rumen VFA. Further validation, with comparisons to rumen fluid, and establishment of the proposed method are required.

Effects of different unconventional feed combinations on growth, digestion and rumen fermentation of dairy cows.

To explore the effects of unconventional feed combinations on the growth and production, digestion and metabolism, and rumen fermentation of dairy cows, three different dairy cows were selected for the experiment. They are Holstein cows with permanent rumen fistula, 3 primiparous cows and 6 multiparous cows. The cow diet was prepared according to the ratio of 0% CGF, 7% CGF and 11% CGF. Part of alfalfa hay in the conventional diet was replaced by CGF and Leymus chinensis. The study analyzed the feed intake, digestibility, lactation performance, blood biochemical indicators, rumen degradation parameters, rumen microorganisms and other indicators of dairy cows. The nutritional composition, digestible nutrients and absorbable protein content of CGF, L. chinensis and alfalfa hay were verified. The feed economic benefits of different unconventional feed combinations were also investigated. The protein small intestine digestibility of CGF was higher than that of alfalfa hay. tdFA, NEm, NEg, and DEp were significantly higher than those of L. chinensis and alfalfa hay (P<0.05). Under the three CGF ratios, the nutrient intake and digestibility of the CGF-11% group were the highest (P<0.05). The S, Kd dry matter degradation rate and crude protein degradation rate of the CGF-11% group were significantly higher than those of the CGF-0% group and CGF-7% group (P<0.05). The CGF-11% group had the highest total output value and economic benefits, 119.057 ¥/d and 68.62 ¥/d respectively. To sum up, it was feasible to use the combination of CGF and L. chinensis to replace part of alfalfa hay in cow feed. This method could effectively promote rumen degradation and nutrient absorption in dairy cows. And it can improve the production and economic benefits of dairy farming. This is of great value for adjusting the structure of aquaculture feed in China.

Effects of fermentative quality of corn silage on lactation, blood metabolites, and rumen fermentation in dairy cows.

We investigated the effect of fermentation quality of corn silage on dry matter intake (DMI), milk yield, ruminal fermentation, methane (CH4 ) emissions, and plasma metabolites in lactating cows. Six lactating Holstein cows were used in a 2 × 2 crossover design with two dietary treatments containing high quality corn silage with lower pH (high group) or low quality corn silage with higher pH (low group). The cows were fed partial mixed ration (PMR containing 50%DM of each corn silage) ad libitum plus 0.7 kg/day of concentrates at milking. The DMI of cows in the low group (24.8 kg/day) tended to be lower (p< 0.10) than that in the high group (26.8 kg/day). The dietary treatment did not affect milk yield or milk fat, protein, or lactose concentrations. The ruminal acetic acid proportion of the low group was significantly higher (p< 0.05) than that of the high group. The CH4 emission per DMI of the low group tended to be higher (p< 0.10) than that of the high group. The plasma concentration of the total cholesterol (TCHO) and the activity of aspartate aminotransferase and alanine aminotransferase of the low group were significantly higher than those of the high group.

Effect of Moringa leaf flavonoids on the production performance, immune system, and rumen fermentation of dairy cows.

Unreasonable use of antibiotics in animals is a major concern and will remain so, thus affecting people's health. However, the application of plant extracts can better solve this problem. The purpose of this study was to study the effect of Moringa leaf flavonoids on the production performance, immunity, and rumen fermentation of dairy cows. Nine Holstein multiparous cows (average weight: 550 kg; days of lactation: 150 ± 6 days) were used in the experiment, using a 3 × 3 Latin square design. Cows were divided into three groups, each of which was supplemented with 0, 50, or 100 mg/body weight (BW) Moringa oleifera leaf flavonoids. Each experimental period consisted of three periods of 21 days, and the prefeeding period lasted 15 days. Our results indicated that supplementation with Moringa leaf flavonoids increased the protein content and decreased the number of somatic cells in milk; had little effect on the biochemical indices of blood, the rumen fermentation, and serum biochemical indicators; and improved the activity of antioxidant enzymes, the antioxidant capacity, and immunity. Addition of 50 mg/BW Moringa leaf flavonoids to cow enhanced the antioxidant and immunity capacity in dairy cows but did not affect physiological levels of common biochemical parameters in blood or fermentation parameters in rumen.

Effects of supplementation of sodium acetate on rumen fermentation and microbiota in postpartum dairy cows.

The primary product of rumen fermentation is acetic acid, and its sodium salt is an excellent energy source for post-partum cows to manage negative energy balance (NEB). However, it is unknown how adding sodium acetate (NAc) may affect the rumen bacterial population of post-partum cows. Using the identical nutritional total mixed ration (TMR), this research sought to characterize the impact of NAc supplementation on rumen fermentation and the composition of bacterial communities in post-partum cows. After calving, 24 cows were randomly assigned to two groups of 12 cows each: a control group (CON) and a NAc group (ACE). All cows were fed the same basal TMR with 468 g/d NaCl added to the TMR for the CON group and 656 g/d NAc added to the TMR for the ACE group for 21 days after calving. Ruminal fluid was collected before morning feeding on the last day of the feeding period and analyzed for rumen bacterial community composition by 16S rRNA gene sequencing. Under the identical TMR diet conditions, NAc supplementation did not change rumen pH but increased ammonia nitrogen (NH3-N) levels and microbial crude protein (MCP) concentrations. The administration of NAc to the feed upregulated rumen concentrations of total volatile fatty acids (TVFA), acetic, propionic, isovaleric and isobutyric acids without affecting the molar ratio of VFAs. In the two experimental groups, the Bacteroidota, Firmicutes, Patescibacteria and Proteobacteria were the dominant rumen phylum, and Prevotella was the dominant rumen genus. The administration of NAc had no significant influence on the α-diversity of the rumen bacterial community but upregulated the relative abundance of Prevotella and downregulated the relative abundance of RF39 and Clostridia_UCG_014. In conclusion, the NAc supplementation in the post-peripartum period altered rumen flora structure and thus improved rumen fermentation in dairy cows. Our findings provide a reference for the addition of sodium acetate to alleviate NEB in cows during the late perinatal period.

Effects of rumen-protected lysine and methionine supplementation in low-crude protein diets on lactation performance, nitrogen metabolism, rumen fermentation, and blood metabolites in Holstein cows

The objective of the study was to investigate the effects of supplementing a low-protein diet with rumen-protected lysine (RP-Lys) and RP-methionine (RP-Met) on milk production, nitrogen metabolism, and rumen fermentation in dairy cows. Forty-eight Holstein dairy cows were blocked by parity (2.1 ± 0.17), milk production (32.1 ± 3.41 kg/d), and days in milk (124 ± 28 d), and randomly assigned to 1 of 4 dietary treatments: control diet (CON, 16 % CP), low-protein diet (LP, 14 % CP, negative control), a moderate diet supplemented with RP-Met (31 g/d) and RP-Lys (MPML, 15 % CP, 110 g/d), and LP diet with RP-Met (50 g/d) and RP-Lys (LPML, 14 % CP, 150 g/d). Dry matter intake (DMI), feed efficiency, and the apparent total tract digestibility of nutrients was not affected by treatments. Compared with the CON, the milk yield was increased in the MPML treatment (P = 0.03) while decreased in the LP treatment (P = 0.02). Milk protein yield in the MPML treatment was higher than that in the other treatments (P < 0.05). The LP, LPML, and MPML treatments had lower concentrations of milk urea-N and plasma urea-N than CON treatments (P < 0.01). The LP, LPML, and MPML treatments decreased the plasma histidine (His) concentration (P < 0.01), while the LP and LPML treatments decreased plasma arginine (Arg) concentration (P < 0.05) compared to the CON treatment. Plasma Met concentration in the MPML treatment was increased (P < 0.01), whereas was decreased in the LP treatment, compared with the CON (P < 0.05). The N intake (g/d) in the LP, LPML, and MPML treatments was lower than that in the CON treatment (P < 0.01), while fecal N (g/d) was not affected by treatments. However, CON treatment increased the urine N (g/d), total excreta N (g/d), N secretion and excretion (g/d), and the proportions of urine N to N intake, whereas decreased the proportion of milk N to N intake and milk N efficiency, compared to the other three treatments (P < 0.01). The rumen concentration of ammonia nitrogen in the LP, LPML, and MPML treatments was lower than that in the CON treatment (P < 0.05). Collectively, the low-protein diets supplemented with RP-Met and RP-Lys could increase milk N efficiency and dramatically decrease urinary N losses. From the perspective of N emission reduction, a 2% reduction in dietary CP was rational.

O102 Diurnal variation in enteric methane emission and rumen fermentation in dairy cows fed with fresh or ensiled sugar beet

O102 Diurnal variation in enteric methane emission and rumen fermentation in dairy cows fed with fresh or ensiled sugar beet

Hydroxy-selenomethionine supplementation promotes the in vitro rumen fermentation of dairy cows by altering the relative abundance of rumen microorganisms.

AimsThis study aims to investigate the effect of hydroxy‐selenomethionine supplementation on the in vitro rumen fermentation characteristics and microorganisms of Holstein cows.Methods and ResultsFive fermentation substrates, including control (without selenium supplementation, CON), sodium selenite supplementation (0.3 mg kg−1 DM, SS03), and hydroxy‐selenomethionine supplementation (0.3, 0.6 and 0.9 mg kg−1 DM, SM03, SM06 and SM09, respectively) were incubated with rumen fluid in vitro. The results showed that in vitro dry matter disappearance and gas production at 48 h was significantly higher in SM06 than SM03, SS03 and CON; propionate and total volatile fatty acid (VFA) production was higher in SM06 than CON. Moreover, higher species richness of rumen fluid was found in SM06 than others. Higher relative abundance of Prevotella and Prevotellaceae‐UCG‐003 and lower relative abundance of Ruminococcus‐1 were detected in SM06 than CON. Besides, higher relative abundance of Ruminococcaceae_UCG‐005 was found in CON than other treatments.ConclusionsIt is observed that 0.6 mg kg−1 DM hydroxy‐selenomethionine supplementation could increase cumulative gas production, propionate, and total VFAs production by altering the relative abundance of Prevotella, Prevotellaceae‐UCG‐003, Ruminococcaceae_UCG‐005 and Ruminococcus‐1, so that it can be used as a rumen fermentation regulator in Holstein cows.Significance and Impact of the StudyThis study provides an optimal addition ratio of hydroxy‐selenomethionine on rumen fermentation and bacterial composition via an in vitro test.

Effects of Heat Stress on the Ruminal Epithelial Barrier of Dairy Cows Revealed by Micromorphological Observation and Transcriptomic Analysis.

Heat stress (HS) alters the rumen fermentation of dairy cows thereby affecting the metabolism of rumen papillae and thus the epithelial barrier function. The aim of the present study was to investigate if HS damages the barrier function of ruminal epithelia. Eight multiparous Holstein dairy cows with rumen cannula were randomly equally allocated to two replicates (n = 4), with each replicate being subjected to heat stress or thermal neutrality and pair-feeding in four environmental chambers. Micromorphological observation showed HS aggravated the shedding of the corneum and destroyed the physical barrier of the ruminal epithelium to a certain extent. Transcriptomics analysis of the rumen papillae revealed pathways associated with DNA replication and repair and amino acid metabolism were perturbated, the biological processes including sister chromatid segregation, etc. were up-regulated by HS, while the MAPK and NF-kB cell signaling pathways were downregulated. However, no heat stress-specific change in the expression of tight junction protein or TLR4 signaling was found, suggesting that HS negatively affected the physical barrier of the ruminal epithelium to some extent but did not break the ruminal epithelium. Heat stress invoked mechanisms to maintain the integrity of the rumen epithelial barrier by upregulating the expression of heat shock protein and repairments in rumen papillae. The increase in amino acid metabolism in rumen papillae might affect the nutrient utilization of the whole body. The findings of this study may inform future research to better understand how heat stress affects the physiology and productivity of lactating cows and the development of mitigation strategies.

Effects of bamboo leaf extract on the production performance, rumen fermentation parameters, and rumen bacterial communities of heat-stressed dairy cows.

ObjectiveAn experiment was conducted to evaluate the effects of bamboo leaf extract (BLE) on the production performance, rumen fermentation parameters, and rumen bacterial communities of heat-stressed dairy cows.MethodsThe experiment comprised a 14-day adaptation period and a 21-day experimental period and was conducted in a high-temperature and humidity environment (daily mean ambient temperature = 33.5°C±1.3°C; daily mean relative humidity = 64.9%±0.8%, daily mean temperature-humidity index = 86.2±0.4). Twelve Holstein dairy cows were randomly allocated into two groups. A total mixed ration supplemented with BLE at 0 (CON) and 1.3 g/kg dry matter (DM) were fed, respectively. Feed intake and milk yield were recorded daily. Milk samples were collected on 1, 11, and 21 d of the experimental period to analyze milk performance. Rumen fluid samples were collected on 21 d of the experimental period to analyze rumen fermentation parameters and rumen bacterial communities.ResultsCompared with the control group, supplementation of BLE increased milk yield (p<0.01), milk fat yield (p = 0.04), 4% fat-corrected milk (p<0.01) and milk fat content (p<0.01); reduced somatic cell count (p<0.01). No differences in DM intake and milk protein or lactose content were observed between two groups. Supplementation of BLE also increased the rumen total volatile fatty acid (p<0.01), acetate (p<0.01), butyrate (p<0.01), and valerate (p = 0.05) concentrations. However, no significant effects were observed on rumen pH, ammonia nitrogen, propionate, acetate/propionate ratio, isobutyrate, or isovalerate. Furthermore, BLE increased the rumen bacterial abundance and the diversity of the rumen bacterial community. The BLE reduced the Firmicutes/Bacteroidetes abundance ratio and increased the abundances of Butyrivibrio_2 (p<0.01) and Ruminococcus_2 (p<0.01).ConclusionThe BLE supplementation at 1.3 g/kg DM could improve production performance and rumen fermentation in dairy cows during heat stress.

Effect of Biological Extract Supplementation on Milk Yield and Rumen Fermentation in Dairy Cows

Effect of Biological Extract Supplementation on Milk Yield and Rumen Fermentation in Dairy Cows

Milk production responses and rumen fermentation of dairy cows supplemented with summer brassicas

Forage brassicas, such as summer turnip (ST; Brassica rapa) and forage rape (FR; Brassica napus), are used as supplementary crops during summer. However, studies with lactating dairy cows fed these forages are limited and report inconsistent productive responses. The aim of this study was to determine dry matter intake, rumen fermentation and milk production responses of dairy cows in mid-lactation supplemented with and without summer (‘ST’ or ‘FR’) brassicas. Twelve multiparous lactating dairy cows were randomly allocated to three dietary treatments in a replicated 3 × 3 Latin square design balanced for residual effects over three 21-day periods. The control diet consisted of 16.2 kg DM of grass silage, 2.25 kg DM of commercial concentrate and 2.25 kg DM solvent-extracted soybean meal. For the other two dietary treatments, 25% of the amounts of silage and concentrates were replaced with FR or ST. The inclusion of forage brassicas had no effects on milk production (24.2 kg cow/day average) and composition (average milk fat and protein 43.2 and 33.6 g/l, respectively). Dry matter intake was 0.98 kg and 1.12 kg lower for cows supplemented with FR and ST, respectively, resulting in a greater feed conversion efficiency (1.35 kg milk/kg DM for ST and FR v. 1.27 kg milk/kg DM for the control diet). Intraruminal pH was lower for cows supplemented with ST compared to the control diet; however, it did not decrease below pH 5.8 at any time of the day. After feeding, the concentrations of total short-chain fatty acids (SCFAs) in rumen contents increased with ST supplementation compared to the control diet. Inclusion of FR in the diet increased the molar proportion of acetate (68.5 mmol/100 mmol) in total SCFA at the expense of propionate, measured 6 h after feeding of the forage. The molar proportion of butyric acid was greater with ST and FR supplementation (13.1 and 12 mmol/100 mmol, respectively) than in control cows. The estimated microbial nitrogen (N) flow was 89.1 g/day greater when supplementing FR compared to the control diet. Based on the haematological measures, the inclusion of summer brassica forages did not affect the health status of the animals. These results indicate that mid-lactation dairy cows fed brassicas are able to maintain production despite the reduced intake, probably due to improved rumen fermentation and therefore nutrient utilization.

Effects of supplementing a Saccharomyces cerevisiae fermentation product during the transition period on rumen fermentation of dairy cows fed fresh diets differing in starch content

The objective of this study was to evaluate the effects of supplementing a Saccharomyces cerevisiae fermentation product (SCFP; NutriTek, Diamond V, Cedar Rapids, IA) during the transition period (d -28 ± 3 to 23 ± 3 relative to calving) on rumen fermentation and mRNA abundance of genes in the rumen epithelium of fresh cows (d 1 to 23 ± 3 after calving) fed diets differing in starch content. Eighteen ruminally cannulated multiparous Holstein cows were fed diets with SCFP (n = 9) or without (CON; n = 9) throughout the experiment. All cows were fed a common basal controlled-energy close-up diet (1.43 Mcal/kg, net energy for lactation; 13.8% starch) before calving. Cows within each treatment (CON or SCFP) were fed either a low-starch (LS; 22.1% starch) or high-starch (HS; 28.3% starch) diet during the fresh period. Cows were assigned to treatment after balancing for parity, body condition score, and expected calving date. Rumen pH was measured continuously for 72 h starting on d -10, -3, 1, 7, and 21 relative to calving date. Rumen papillae were collected on d -10 and 21 relative to calving. Supplementation of SCFP had no effect on rumen pH during d -10 to -8, but mean rumen pH tended to be higher (6.64 vs. 6.49) for SCFP cows than for CON cows during d -3 to -1. Feeding SCFP decreased the range of rumen pH variation compared with CON within the HS group during both d 7 to 9 (1.08 vs. 1.38) and d 21 to 23 (1.03 vs. 1.30) after calving. In addition, nadir rumen pH tended to be higher (5.64 vs. 5.44) and duration of pH below 5.8 tended to be shorter (116 vs. 323 min/d) for the SCFP group than for the CON group during d 21 to 23 after calving. Supplementation of SCFP increased the mRNA abundance of insulin-like growth factor-6 (1.10 vs. 0.69) before calving and decreased the mRNA abundance of putative anion transporter isoform 1 (1.12 vs. 2.27) after calving. Nadir rumen pH tended to be higher during d 1 to 3 (5.63 vs. 5.41) for LS cows than for HS cows, but rumen pH was not affected by dietary starch content during other time periods. Dietary starch content had no effect on mRNA abundance of genes in the rumen epithelium after calving. These results suggest that supplementation of SCFP may reduce the range of variation in rumen pH in fresh cows fed HS diets and the duration of subacute ruminal acidosis by the end of the fresh period regardless of dietary starch content and that decreasing dietary starch content during the fresh period may reduce the decrease in rumen pH immediately after parturition.

The effects of supplementation of rumen-protected choline on some blood and milk metabolites in the transition period of dairy cattle

The aim of this study was to investigate nonesterified fatty acid (NEFA), beta-hydroxy butyric acid (BHBA), and milk urea nitrogen (MUN) profiles for dairy cows fed with rumen-protected choline (RPC) during the transition period. A total of 30 dairy cows were allocated to one control and two experimental groups (10 animals per group) and were fed from 3 weeks before calving to 21 days in milk. The control was fed only the basal diet. Treatment groups 1 and 2 were fed a basal diet containing 60 and 120 g/head/day RPC, respectively. The differences between groups were insignificant for MUN levels of colostrum and milk. There were no significant differences (P > 0.05) between the groups in terms of serum NEFA or BHBA levels. RPC supplementation did not have a significant effect on energy or protein metabolism of dairy cows during the transition period. The main effects of the periods without group effects in the model were highly significant (P < 0.01) for NEFA and BHBA. There is no need to add RPC to rations formulated as isocaloric and isonitrogenic for optimal rumen fermentation in dairy cows during the transition period. To better understand the effect of RPC on dairy cows during the transition period, there is a need for further studies of animals with known metabolic profiles, and those having high milk yields or metabolic disorders.

Effect of dietary nitrate on enteric methane emissions, production performance and rumen fermentation of dairy cows grazing ryegrass pasture during spring

Limited studies investigated the effect of dietary nitrate addition as methane (CH4) mitigation strategy for dairy cows grazing pasture. This study aimed to investigate the effect of dietary nitrate addition on daily enteric CH4 emissions, production performance and rumen fermentation of multiparous Jersey cows grazing perennial ryegrass pasture (containing approximately 7.3 g of nitrate/kg of dry matter (DM)). Thirty-two intact and eight rumen-cannulated multiparous Jersey cows were subjected to a replicated 2 × 2 Latin square design with 16 intact cow replicates and four rumen-cannulated cow replicates supplemented with one of two concentrates containing either urea (urea treatment), or urea and nitrate (nitrate treatment) as nonprotein nitrogen source (NPN; containing 0.3 and 15.2 g of nitrate/kg of DM, respectively). Concentrates were formulated to be isonitrogenous and isoenergetic, and was fed at 5.4 kg of DM/cow per d along with a strict daily herbage allowance of 14 kg of DM/cow. Cows were gradually adapted to concentrates over a 3-wk period. Total nitrate intake was 5.2 and 9.7 g of nitrate/kg of DM for the urea and nitrate treatment groups, respectively. Daily enteric CH4 emissions of 28 cows were measured with the sulphur hexafluoride tracer gas technique for six consecutive days during each experimental period with parallel total DM intake (DMI) estimates. Pasture DMI was calculated from faecal output and pasture digestibility using TiO2 and indigestible neutral detergent, respectively. Total DMI (18.1 and 17.8 kg/d), milk yield (19.0 and 18.9 kg/cow per d) and daily CH4 emissions (400 and 405 g/d) were unaffected by dietary treatment for the urea and nitrate group, respectively. Total milk solids content (135 vs. 133 g/kg), milk lactose content (47.3 vs. 46.7 g/kg) and milk urea nitrogen concentration (MUN; 12.6 vs. 11.6 mg/dL) were higher for the nitrate group. Rumen fermentation parameters such as volatile fatty acid profile, ammonium nitrogen, and DM and fibre disappearance were unaffected by treatment. Minor effects on ruminal pH were observed with an increasing tendency towards the nitrate group. In this study, dietary nitrate supplementation was not an effective CH4 mitigation strategy for dairy cows grazing perennial ryegrass. This can be ascribed to the unforeseen high nitrate content of the grazed pasture causing a relative small margin in total nitrate intake between the urea and nitrate treatment diets.

Effects of rice conservation methods on lactation, blood metabolites, and rumen fermentation in dairy cows.

We investigated the effect of rice grain conservation methods on feed intake, milk production, blood metabolites, and rumen fermentation in dairy cows. Raw rice grain was dried before crushing (DRY), ensiled after crushing (ENS-A), or ensiled before crushing (ENS-B). Twelve multiparous Holstein cows were used in a replicated 3×3 Latin square design with three dietary treatments comprising ad libitum access to one of three total mixed rations (TMRs; containing DRY, ENS-A, or ENS-B at 17% of dietary dry matter) plus a standard allowance of 2.0kg/day of dairy concentrates. The dietary treatments did not affect the feed intake, milk yield, or milk composition. The selected blood constituents were not influenced by the rice conservation method. The ruminal lactic acid and total volatile fatty acid (VFA) concentrations and the VFA proportion in the cows were not influenced by the rice conservation method. These results demonstrate that the rice grain conservation method has little impact on lactation performance when cows are fed a TMR containing 17% treated rice grain (dry matter basis).

Lactation performance and rumen fermentation in dairy cows fed a diet with alfalfa hay replaced by corn stover and supplemented with molasses.

ObjectiveThe objective of current study was to investigate the lactation performance and rumen fermentation characteristics of dairy cows fed a diet with alfalfa hay replaced by corn stover but supplemented with molasses.MethodsSixteen Holstein cows in mid-lactation were randomly assigned to 1 of 2 dietary treatments: i) alfalfa based diet (AH), and ii) corn stover based diet supplemented with molasses (CSM). The experiment was conducted according to a 2×2 crossover design with 22-d each period, consisting of 17 d for adaptation and 5 d for data and samples collection.ResultsDry matter intake and milk yield were higher for cows fed AH than CSM (p<0.01). Milk protein content and nitrogen conversion were higher (p<0.05), while milk urea nitrogen was lower (p<0.01) for cows fed AH than CSM-fed cows. Contents of milk total solids, fat and lactose were not different between two groups (p>0.10). Total rumen volatile fatty acid concentration tended to be higher (p = 0.06) for cows fed AH than CSM-fed cows. Molar proportion of acetate was lower (p = 0.04), but valerate was higher (p = 0.02) in cows fed AH than CSM-fed cows. Rumen concentration of propionate, and isobutyrate, and ratio of acetate to propionate tended to be different (p<0.10) between two groups. The feed cost per kilogram of milk was lower in CSM than AH (p<0.01). No differences were found in feed efficiency and most plasma parameters tested (p>0.10).ConclusionIn comparison with AH diet, CSM diet could be fed to dairy cows without negative effect on feed efficiency, ruminal fermentation, but economically beneficial, indicating that CSM could be an alternative choice for dairy farms instead of AH to feed mid-lactation dairy cows.