High-grain Feeding Research Articles

Active dry Saccharomyces cerevisiae can alleviate the effect of subacute ruminal acidosis in lactating dairy cows

The objective of the study was to determine the effect of active dry Saccharomyces cerevisiae (ADSC) supplementation on dry matter intake, milk yield, milk components, ruminal pH, and microbial community during a dietary regimen that leads to subacute ruminal acidosis (SARA). Sixteen multiparous, rumen-cannulated lactating Holstein cows were randomly assigned to 1 of 2 dietary treatments that included ADSC (Biomate; AB Vista, Marlborough, UK; 8×1010 cfu/head per day) or control. During wk 1 to 6, all cows received a high-forage (HF) diet (77:23, forage:concentrate). Cows were then abruptly switched during wk 7 to a high-grain (HG) diet (49:51, forage:concentrate) and remained on the HG until the end of wk 10. Feed intake and milk yields were recorded daily. Ruminal pH was recorded continuously using an indwelling system for 1 to 2 d per week during the pre-experimental phase, and wk 6, 7, and 10. Ruminal digesta samples were collected at the end of the experiment and analyzed for relative change in microbial communities using real-time quantitative PCR. Cows were considered to have SARA if the duration below pH 5.6 was ≥300min/d. Ruminal pH during wk 6 (HF plateau) was not different across treatments (15±46min/d at pH <5.6). The dietary regimen successfully induced SARA during wk 7 (transition from HF to HG diet), and ruminal pH (551±46min/d at pH <5.6) was not different across treatments. However, cows receiving ADSC had an improved ruminal pH (122±57 vs. 321±53min/d at pH <5.6) during wk 10 (HG plateau) compared with control. Additionally, cows receiving ADSC had a better dry matter intake (23.3±0.66 vs. 21.6±0.61kg/d) and 4% fat-corrected milk yield (29.6±1.2 vs. 26.5±1.2kg/d) than control cows during the HG phase (wk 8 to 10). During HG feeding, cows receiving ADSC had greater total volatile fatty acid and propionate concentrations (175±7.5 vs. 154±7.5 and 117±6.1 vs. 94±5.7mM for ADSC and control, respectively) and lower acetate:propionate ratio (0.26±0.5 vs. 0.36±0.05 for ADSC and control, respectively). Microbial analyses conducted on samples collected during wk 10 showed that cows supplemented with S. cerevisiae had a 9-fold, 2-fold, 6-fold, 1.3-fold, and 8-fold increase in S. cerevisiae, Fibrobacter succinogenes, Anaerovibrio lipolytica, Ruminococcus albus, and anaerobic fungi, respectively, which suggested an increase in cellulolytic microbes within the rumen. Cows supplemented with ADSC had 2.2-fold reduction in Prevotella albensis, which is a gram-negative bacterium predominant during SARA. Prevotella spp. are suggested to be an important source of lipopolysaccharide responsible for inflammation within the rumen. Cows supplemented with ADSC had a 2.3-fold increase in Streptococcus bovis and a 12-fold reduction in Megasphaera elsdenii. The reduction in M. elsdenii may reflect lower concentration of lactic acid within the rumen for ADSC cows. In conclusion, ADSC supplementation to dairy cows was demonstrated to alleviate the condition of SARA caused by abrupt dietary changes from HF to HG, and can potentially improve rumen function, as indicated by greater numbers of cellulolytic microorganisms within the rumen.

High-grain feeding alters caecal bacterial microbiota composition and fermentation and results in caecal mucosal injury in goats

The effect of high-grain (HG) feeding on caecal bacterial microbiota composition and fermentation and mucosa health is largely unknown. In the present study, ten male goats were randomly assigned to either a group fed a hay diet (0 % grain; n 5) or a group fed a HG diet (65 % grain; n 5) to characterise the changes in the composition of the bacterial community and mucosal morphology in the caecum. After 7 weeks of feeding, the HG diet decreased the caecal pH (P< 0·001) and increased (P< 0·001 to P< 0·004) the caecal digesta concentrations of total volatile fatty acids and lipopolysaccharide (LPS). Pyrosequencing of the 16S ribosomal RNA gene revealed that HG feeding increased (P= 0·001 to P= 0·009) the abundance of predominant genera Turicibacter and Clostridium in the caecal lumen and in the caecal mucosa and decreased (P< 0·001 to P< 0·009) the proportion of Bacteroides in the lumen and Mucispirillum in the mucosa compared with the hay diet. Furthermore, the HG diet-fed goats exhibited intense epithelial damage and up-regulation (P< 0·001 to P< 0·025) of the relative mRNA expression of IL-1β, IL-6, IL-12 and interferon-γ (IFN-γ) in the caecal mucosa. The correlation analysis revealed that alterations in caecal pH, LPS concentration and mucosa-associated microbiota abundance during HG feeding might partly contribute to local inflammation. Collectively, these results provide insight into the adaptive response of caecal bacterial populations to HG feeding in goats and reveal that the fermentable substrates that flow into the caecum may cause dramatic alterations in microbial compositions and play a significant role in caecal dysfunction.

Impact of subacute ruminal acidosis on the diversity of liquid and solid-associated bacteria in the rumen of goats

This study was aimed to investigate the impact of subacute ruminal acidosis (SARA) on the diversity of liquid (LAB) and solid-associated bacteria (SAB) following high-grain feeding. Six ruminally cannulated goats were divided into two groups: one group was fed a hay diet (COD), and the other group was fed a high grain diet (SAID). Rumen liquids and rumen solids were sampled after 2 weeks adaption. SARA was diagnosed with a pH below 5.8 for 8 h. SAID decreased ruminal pH (P < 0.001) and increased the acetate (P = 0.017), propionate (P = 0.001), butyrate (P < 0.001) and total volatile fatty acid (P < 0.001) concentration in rumen compared with the COD. Denaturing gradient gel electrophoresis fingerprints analysis revealed a clear separation between both the diet and the fraction of rumen digesta in bacterial communities. Pyrosequencing analysis showed that the proportion of phylum Bacteroidetes in the SAID-LAB and SAID-SAB communities was less than in the COD group, whereas the SAID group had a greater percentage of Firmicutes in both the LAB and SAB libraries. UniFrac analyses and a Venn diagram revealed a large difference between the two diets in the diversity of rumen bacterial communities. Overall, our findings revealed that SARA feeding did alter the community structure of rumen liquids and rumen solids. Thus, manipulation of dietary factors, such as ratio of forage to concentrate may have the potential to alter the microbial composition of rumen liquid and rumen solid.

Feeding barley grain-rich diets altered electrophysiological properties and permeability of the ruminal wall in a goat model

High-producing ruminants are commonly fed large amounts of concentrate to meet their high energy demands for rapid growth or high milk production. However, this feeding strategy can severely impair rumen functioning, leading to subacute ruminal acidosis. Subacute ruminal acidosis might have consequences for electrophysiological properties by changing the net ion transfer and permeability of ruminal epithelia, which may increase the uptake of toxic compounds generated in the rumen into the systemic circulation. The objective of the present study was to investigate the effects of excessive barley feeding on the electrophysiological and barrier functions of the ruminal epithelium and serum inflammation and ketogenesis markers after a long-term feeding challenge, using growing goats as a ruminant model. A feeding trial was carried out with growing goats allocated to 1 of the 3 groups (n=5–6 animals/group), with diets consisting exclusively of hay (control diet) or hay with 30 or 60% barley grain. Samples of the ventral ruminal epithelium were taken after euthanasia and instantly subjected to Ussing chamber experiments, where electrophysiological properties of the epithelium were measured in parallel with the permeability of marker molecules of different sizes [fluorescein 5(6)-isothiocyanate and horseradish peroxidase] from luminal to apical side. Additionally, ruminal fluid and blood samples were taken at the beginning of the experiment as well as shortly before euthanasia. Ruminal fluid samples were analyzed for volatile fatty acids and pH, whereas blood samples were analyzed for lipopolysaccharide, serum amyloid A, and β-hydroxybutyrate. Electrophysiological data indicated that barley feeding increased the epithelial short-circuit current compared with the control. Tissue conductance also increased with dietary barley inclusion. As shown with both marker molecules, permeability of ruminal epithelia increased with barley inclusion in the diet. Despite a lowered ruminal pH associated with increased volatile fatty acids (such as propionate and butyrate) concentrations as well as altered epithelial properties in response to high-grain feeding, no signs of inflammation became apparent, as blood serum amyloid A concentrations remained unaffected by diet. However, greater amounts of grain in the diet were associated with a quadratic increase in lipopolysaccharide concentration in the serum. Also, increasing the amounts of barley grain in the diet resulted in a tendency to quadratically augment serum concentrations of β-hydroxybutyrate and, hence, the alimentary ketogenesis. Further studies are needed to clarify the role of barley inclusion in the development of subacute ruminal acidosis in relation to ruminal epithelial damage and the translocation of toxic compounds in vivo.

Impact of subacute ruminal acidosis (SARA) adaptation and recovery on the density and diversity of bacteria in the rumen of dairy cows

Subacute ruminal acidosis (SARA) is characterized by ruminal pH depression and microbial perturbation. The impact of SARA adaptation and recovery on rumen bacterial density and diversity was investigated following high-grain feeding. Four ruminally cannulated dairy cows were fed a hay diet, transitioned to a 65% grain diet for 3 weeks, and returned to the hay diet for 3 weeks. Rumen fluid, rumen solids, and feces were sampled during weeks 0 (hay), 1 and 3 (high grain), and 4 and 6 (hay). SARA was diagnosed during week 1, with a pH below 5.6 for 4.6±1.4 h. Bacterial density was significantly lower in the rumen solids with high grain (P=0.047). Rumen fluid clone libraries from weeks 0, 3, and 6 were assessed at the 98% level and 154 operational taxonomic units were resolved. Week 3 diversity significantly differed from week 0, and community structure differed from weeks 0 and 6 (P<0.0001). Clones belonging to the phylum Firmicutes predominated. Compared with the hay diet, the high-grain diet contained clones from Selenomonas ruminantium and Succiniclasticum ruminis, but lacked Eubacterium spp. SARA adaptation was found to significantly alter bacterial density, diversity, and community structure, warranting further investigation into the role bacteria play in SARA adaptation.

Effects of winter growing programs on subsequent feedlot performance, carcass characteristics, body composition, and energy requirements of beef steers12

The purpose of this study was to investigate the effects of winter growing program on subsequent finishing performance, carcass merit, and body composition of beef steers. Four steers were slaughtered to determine initial body composition. Remaining steers (n = 256) were blocked by BW and randomly allotted to 1 of 4 treatment groups: 1) ad libitum fed a high-concentrate diet (CF), 2) grazed on wheat pasture (WP), 3) fed a sorghum silage-based diet (SF), or 4) program fed a high-concentrate diet (PF). Steers in the WP, SF, and PF groups were managed to achieve approximately equal rates of BW gain. After the growing phase (112 d), 6 steers were randomly selected from the WP, SF, and PF treatments for determination of body composition. Remaining steers were adapted to a high-concentrate diet for finishing and slaughtered at 1.27 cm of 12th-rib fat. Six steers from each treatment were used to determine carcass, offal, and empty body composition. During the growing phase, WP, SF, and PF steers gained 1.15, 1.10, and 1.18 kg/d, respectively, and ME intake did not differ (P = 0.50) among treatments. Program-fed and SF steers had greater (P < 0.05) offal and empty body fat content than WP steers. Gain in offal and empty body fat was greatest (P < 0.05) for PF steers, intermediate for SF steers, and least for WP steers. During the finishing phase (123, 104, 104, 196 d for WP, SF, PF, and CF, respectively) DMI was greater (P < 0.01) for SF steers (10.9 kg/d) than for PF steers (10.1 kg/d); WP steers were intermediate (10.4 kg/d). Daily BW gain was greatest (P < 0.05) for SF steers (2.02 kg/d), intermediate for PF steers (1.85 kg/d), and least for WP and CF steers (1.64 and 1.63 kg/d, respectively). Accretion (kg/d) of carcass and empty body mass was less (P < 0.05) for WP and CF steers compared with PF and SF steers. Calf-fed steers had greater (P < 0.05) fat content of offal than SF and PF steers; WP steers were intermediate. Gain in empty body and carcass energy (Mcal/d) was greater (P < 0.05) for PF steers than CF steers with SF and WP steers being intermediate. At slaughter, SF steers had reduced (P < 0.01) yield grades and greater marbling scores compared with CF and WP steers; PF steers were intermediate. In conclusion, growing programs that increase fat composition of feeder calves did not negatively affect subsequent finishing performance. Finishing steers as calves may reduce retained energy of carcass tissues and increase internal fat during high-grain feeding compared with steers that previously underwent a growing program.

Technical note: The use of a telemetric system to continuously monitor ruminal temperature and to predict ruminal pH in cattle

The objective of this study was to compare a telemetric monitoring system to an existing in situ methodology (conventional system) of monitoring ruminal temperature and to validate its use to detect changes in ruminal pH (RpH). Four nonlactating, ruminally cannulated Holstein dairy cows (760±30kg of body weight, mean±standard deviation) housed in a tie-stall facility were used in the study. The experiment was conducted during the month of May and the recorded ambient temperature was 8.0±2.0°C (mean±SD). The cows were fed a diet consisting of chopped mixed hay (MH; 11.3% crude protein, 59.7% neutral detergent fiber, 17.3% nonfiber carbohydrate, 3.1% ether extract, and 11.3% ash; dry matter basis) during wk 1 and were gradually switched to a high-grain (HG) diet (11.6% crude protein, 30.2% neutral detergent fiber, 50.7% nonfiber carbohydrate, 3.0% ether extract, and 6.0% ash; dry matter basis) during wk 2. A conventional system that utilized an indwelling electrode was used to monitor RpH and ruminal temperature (RTC) during d 6 and 7 of each week. The indwelling electrode was attached to a telemetric bolus and ruminal temperature (RTT) was logged into a personal computer. The daily mean, minimum, and maximum RpH and duration (min/d) RpH <6.2 were 6.39±0.04, 6.10±0.05, 6.66±0.03, and 107±50 during MH feeding (wk 1) and 5.84±0.03, 5.35±0.05, 6.35±0.03, and 1,257±40 during HG feeding (wk 2), respectively, and were different across diets (week effect). Ruminal pH did not decrease below 5.6, 5.8, and 6.0 during MH feeding; mean duration of RpH <5.6, <5.8, and <6.0 during HG feeding was 279±149, 611±139, and 894±101, respectively. Mean daily RTC increased from 37.5̊C±0.1 in wk 1 to 38.6°C±0.1 in wk 2; there was also an increase from wk 1 to wk 2 in minimum and maximum daily RTC and durations (min/d) of RTC >38.0, >38.2, >38.4, and >38.6°C. These increases were not detectable with the telemetric system. Ruminal temperature obtained by the conventional system was 0.68°C±0.005 lower than RTT during MH feeding (wk 1), whereas RTC was 0.04°C±0.004 higher than RTT during HG feeding (wk 2). Daily minimum RpH was associated with maximum daily RTC and RTT during MH and HG feeding (R2=0.88 and 0.43, respectively). There was a high association between low RpH and high ruminal temperature, with the highest associations being between duration (min/d) of RpH <6.0 and duration of RTC >39.0°C (R2=0.68) and RTT >39.2°C (R2=0.72). Unlike the telemetric system, the conventional system requires cow cannulation; therefore, the current study provided a noninvasive alternative for measuring ruminal temperature and the prediction of RpH. Additional studies are needed to develop an algorithm that accounts for diet type, seasonal variation in temperature, and core body temperature to predict subacute ruminal acidosis effectively on farm.

Effect of the live weight gain of steers during winter grazing on digestibility, acid-base balance, blood flow, and oxygen consumption by splanchnic tissues during adaptation and subsequent feeding of a high-grain diet1,2

Ten multicatherized steers were used in a completely random design to determine the effect of previous BW gain on blood flow, acid-base balance, and oxygen consumption across portal-drained viscera and liver of growing beef steers fed a high-grain diet. Treatments were high (1.31 +/- 0.09 kg/d) or low (0.68 +/- 0.07 kg/d) daily BW gain during an 82-d winter wheat pasture grazing period and a subsequent 37-d transition period. Blood flow, blood gas measurements, and oxygen consumption were determined on d 0, 14, 28, 42, and 64 of a high-grain finishing period. Compensatory growth was evident in low-gain steers; ADG (1.50 vs. 1.11 kg/d, P < 0.05) and gain efficiency (0.221 vs. 0.109 kg/kg, P < 0.01) were greater from d 14 through 28 than for high-gain steers. Arterial base tended (P < 0.12) to be greater in low-gain than in high-gain steers, whereas calculated HCO3- (mmol/L; P < 0.20) did not differ between treatments. Arterial O2 concentration was not different (P < 0.97) between treatments but increased (P < 0.001) with increasing days on feed. Portal blood flow increased with days on feed (P < 0.001) but did not differ (P < 0.34) between treatments. Hepatic blood flow scaled to metabolic BW was 19.7% greater (P < 0.02) in low-gain than in high-gain steers. Across the feeding period, O2 consumption and CO2 flux by PDV, liver, and total splanchnic tissue (TST) did not differ (P < 0.33) between treatments. However, TST O2 consumption (mmol/[h x kg BW(0.75)]) tended (P < 0.12) to be greater in low- than in high-gain steers. Compensating steers' arterial blood acid-base measurements did not change with days on feed, indicating that they were not more susceptible to metabolic acidosis than high-gain steers. However, steers that had lower BW gain before high-grain feeding exhibited increased hepatic blood flow and TST O2 consumption (metabolic BW basis) during the finishing period compared with high-gain steers. Greater hepatic blood flow and energy expenditure by TST of previously restricted steers might have facilitated compensatory growth.

Effect of the addition of live yeast (Saccharomyces cerevisiae) on growth and carcass quality of steers fed high-forage or high-grain diets and on feed digestibility and in situ degradability.

The effects of adding yeast culture (Saccharomyces cerevisiae, 5 x 10(9) live organisms/g of growth medium) at 10 g/steer daily to three diets consisting of 75% alfalfa silage and 25% barley, 96% corn silage and 4.0% soybean meal, or 75% dry-rolled barley and 25% alfalfa hay on performance of growing and finishing steers and carcass characteristics, feed digestibility, and degradability in the rumen were determined. In separate trials over 2 yr, the performance of steers fed the three diets with no supplementary live yeast (control; C) or with live yeast (Y) was determined using 72 Hereford steer calves in eight pens each year in a randomized complete block design. The diets were fed sequentially and the steers were randomized before diets were switched. Each year at the end of the high-grain feeding segment of the trial, the steers were slaughtered when ultrasound backfat was such that the carcass would grade A1 or A2 (Canadian grades). The digestibility of feed DM, CP, and NDF of the three diets was determined sequentially using six and eight mature, ruminally cannulated steers in 2 yr, respectively. The degradation characteristics of the three diets in the rumen were determined using the nylon bag technique in two steers for each additive treatment. In the 1st yr, the feed efficiency of the corn silage diet was lower (P < .05) for C than for Y steers (5.9 vs 6.8). Differences (P < .05) were not observed between C and Y steers for any of the performance or carcass characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Rumen bacterial endotoxins and their possible role in the sudden-death syndrome (1979)

We have found that rumen bacteria contain endotoxins that are released into rumen fluid. Also rumen fluid from grain-fed cattle contains considerably more free endotoxin than rumen fluid from hay-fed cattle. Injecting cattle with rumen bacterial endotoxins may be involved with such diseases associated with high-grain feeding as the sudden death syndrome.

Metabolism of Fatty Acids by Adipose Tissue and Liver of Cows Fed Normal, Restricted Roughage or MgO Supplemented Rations

Two Latin square experiments used 11 lactating cows to study dietary effects on fatty acid metabolism in serum, liver, and adipose tissue. Lipoprotein lipase and fatty acid esterifying activities from adipose tissue homogenates were increased and milk fat depressed when the ration was switched from normal to restricted-roughage, high-grain. Fatty acid esterification in liver was correlated (r = .89) with milk fat concentration but was not uniformly affected by ration. Mammary gland uptake of triglycerides from dextran sulfate precipitable lipoproteins and milk fat percentage was greater for cows fed MgO supplemented rations than for cows fed the other rations. The proportion of stearic acid decreased and C18:1 increased in the dextran sulfate precipitable lipoprotein triglycerides for cows fed restricted-roughage, high-grain rations compared to those fed other rations. Only stearic acid was selctively assimilated by the mammary gland. Cholesterol linoleate increased in the dextran sulfate precipitable lipoproteins when rations were switched from normal to restricted-roughage, high-grain. Changes in both serum lipids and tissue enzymes are associated with an increased flux of fatty acids toward adipose tissues during restricted-roughage, high-grain feeding.

Milk Protein Synthesis as Affected by High-Grain, Low-Fiber Rations

Thirty-six Holstein cows were fed the following rations in two trials which lasted 50 days each: A) forage ad libitum plus 1kg concentrate per 3kg milk; B) concentrate ad libitum plus 2.7 to 3.2kg air-dry forage; C) B plus 7% partially delactosed whey, 1.25% NaHC03, and 0.5% MgO in the concentrate. Milk yields tended to be lower for B than A and C in Trial 1, though differences were not significant. Cows were earlier in lactation in Trial 2 than 1, and milk production did not differ between treatments. Protein concentrations in milk were higher for high-grain groups in both trials. Greater yields of milk protein (P<.05) resulted from high-grain feeding in Trial 2. Since the additives tended to increase milk fat and also shifted rumen volatile fatty acids towards patterns for normal rations, the increased milk protein was not dependent on increased ruminal propionate and was compatible with correction of the milk fat depression.α-Casein and β-lactoglobulin accounted for the increase in milk protein, whereas milk serum albumins and “other nitrogens” decreased. Concentration of α-lactalbumin was correlated 0.88 with milk production.

Relationship of Certain Milk Fat Depressing Diets to Changes in the Proportions of the Volatile Fatty Acids Produced in the Rumen

Summary Twelve high-producing Holstein cows were used to study the effect of feeding cod liver oil and a high-grain restricted roughage ration on milk and fat production, fatty acid composition of the milk fat, and the proportions of volatile fatty acids in the rumen. The cod liver oil and high-grain rations did not significantly alter milk production when compared to a control diet; however, these rations did significantly lower the fat content of the milk produced. When cod liver oil was added to a normal ration of hay and grain, the proportions of the volatile fatty acids in the rumen were unaltered; whereas, the high-grain diet caused a significant decrease in the proportion of acetate and a significant increase in propionate. As a result of these findings, it was concluded that cod liver oil exerts its effect on milk fat production somewhere beyond the rumen, whereas the fat depressing effect of high-grain feeding must be attributed to the significant changes occurring in the rumen fermentation.

High Levels of Grass Silage for Milk Production with No Grain, Medium, and High Grain Feeding. 1. Intake, Milk Production, and Body Weight Changes

Summary A three-lactation study with 18 Holstein and six Guernsey cows compared roughage intake, milk production, and weight changes on three levels of grain feeding (no grain, medium grain—1:6, and high grain—1:3) with maximum molasses-grass silage intake in addition to 5lb. good alfalfa hay. Pasture was supplied during the summer. For each pound of grain fed, roughage dry matter intake decreased 0.23lb. Average hay equivalent intake was 2.15lb. over all groups. Average 245-day 4% FCM production for 12 cows with an estimated potential of 8,830lb. was 6,490, 7,690, and 8,910lb. on the three rations; for 12 cows with an estimated potential of 10,930lb., production on the three rations was 8,080, 10,100, and 12,960lb., respectively. There was no evidence of carry-over effects in the reversal phase or cumulative effects in the continuous phase. There was a close relationship between potential producing ability of the cows and response, measured as the ratio of extra milk produced per pound of grain fed, comparing production on high grain with that on no grain (r = 0.88). Cows which had a 245-day potential of 8,900lb. FCM gave 0.58lb. milk per pound grain fed; whereas, those with a 245-day potential of 11,700lb. FCM gave 1.35lb. milk per pound grain fed. There was no evidence of diminishing returns in the high-potential cows, and relatively little for the lower-potential cows. Differences in rate of decline in production during the lactation were not apparent after the first 11 wk. of lactation, with little change after 6 wk. Though cows receiving no grain lost considerable weight from the first to the fourth month (−106lb.), compared with the high-grain cows (+16lb.), they gained more in the latter part of lactation (190 vs. 142lb.) ; however, they still did not regain their precalving weight in 50 wk. High-grain feeding may be profitable for cows with the potential for high production, but not for cows with lower potential, when fed large amounts of good-quality molasses-grass silage.