High-grain Ration Research Articles

Postbiotics from Saccharomyces cerevisiae fermentation stabilize rumen solids microbiota and promote microbial network interactions and diversity of hub taxa during grain-based subacute ruminal acidosis (SARA) challenges in lactating dairy cows.

High-yielding dairy cows are commonly fed high-grain rations. However, this can cause subacute ruminal acidosis (SARA), a metabolic disorder in dairy cows that is usually accompanied by dysbiosis of the rumen microbiome. Postbiotics that contain functional metabolites provide a competitive niche for influential members of the rumen microbiome, may stabilize and promote their populations, and, therefore, may attenuate the adverse effects of SARA. This study used a total of 32 rumen-cannulated lactating dairy cows, which were randomly assigned into four treatments: no SCFP (control), 14 g/d Original XPC (SCFPa), 19 g/d NutriTek (SCFPb-1X), and 38 g/d NutriTek (SCFPb-2X) (Diamond V, Cedar Rapids, IA) from 4 weeks before until 12 weeks after parturition. Grain-based SARA challenges were conducted during week 5 (SARA1) and week 8 (SARA2) after parturition by replacing 20% dry matter of the base total mixed ration (TMR) with pellets containing 50% ground barley and 50% ground wheat. The DNA of rumen solids digesta was extracted and subjected to V3-V4 16S rRNA gene sequencing. The characteristics of rumen solids microbiota were compared between non-SARA (Pre-SARA1, week 4; Post-SARA1, week 7; and Post-SARA2, weeks 10 and 12) and SARA stages (SARA1/1, SARA1/2, SARA2/1, SARA2/2), as well as among treatments. Both SARA challenges reduced the richness and diversity of the microbiota and the relative abundances of the phylum Fibrobacteres. Supplementation with SCFP promoted the growth of several fibrolytic bacteria, including Lachnospiraceae UCG-009, Treponema, unclassified Lachnospiraceae, and unclassified Ruminococcaceae during the SARA challenges. These challenges also reduced the positive interactions and the numbers of hub taxa in the microbiota. The SCFPb treatment increased positive interactions among microbial members of the solids digesta and the number of hub taxa during the SARA and non-SARA stages. The SCFPb-2X treatment prevented changes in the network characteristics, including the number of components, clustering coefficient, modularity, positive edge percentage, and edge density of the microbiota during SARA challenges. These challenges reduced predicted carbohydrate and nitrogen metabolism in microbiota, whereas SCFP supplementation attenuated those reductions. Supplementation with SCFP, especially the SCFPb-2X attenuated the adverse effects of grain-based SARA on the diversity and predicted functionality of rumen solids microbiota.

314 Dehydrated Garlic Powder Did Not Influence Enteric Gas Fluxes in Feedlot Steers

Abstract This 2-yr study was conducted to evaluate the biochemical profiles of commercial dehydrated garlic powder (DGP) and its associated influence on enteric gas fluxes, mineral intake, and body performance at a 5% inclusion level. The DGP was assessed for the stability of the bioactive compounds, especially those responsible for garlic flavor. Each year, resealed (NE) and exposed-to-air (E) DGPs were sampled serially in storage at months 0, 1, 2, and 3. Crossbred steers (n = 40 in year 1; n = 80 in year 2) were assigned to either 5%DGP or 0%DGP treatment group in a randomized complete block design, balancing for initial body weight and breed composition. Feed and supplement intakes for individual animals were monitored using an automatic feeding system. Each year, steers were fed high-grain rations in feed bunks separate from mineral supplement bunks on a free-choice basis over 72 and 82 days, respectively. Methane (CH4), carbon dioxide (CO2), oxygen (O2), and hydrogen (H2) fluxes were also measured using an automatic head-chamber emission monitoring system. Data were analyzed using a linear model in R software with year and treatment as fixed effects. Organosulfur compounds were quantified using Ultra-Performance Liquid Chromatography and Gas Chromatography. No differences (P > 0.05) were observed for allicin, allyl methyl sulfide, dimethyl trisulfide, allyl propyl disulfide, diallyl disulfide, and diallyl trisulfide concentrations in NE-DGP. In E-DGP, the greatest (P < 0.05) concentrations of allicin, diallyl sulfide, and 2-vinyl-4H-1,3-dithiin were recorded at month 1, while other compounds remained stable (P > 0.05) throughout storage months. There were no differences (P > 0.05) in dry matter intake, average daily gain, and the gain-to-feed ratio between 5%DGP and 0%DGP groups. Garlic supplementation did not also influence (P > 0.05) body composition (ribeye area, intramuscular fat, rump fat thickness, and rib fat thickness) of steers, but supplement intake was higher (P < 0.0001) in 5%DGP (204.31 gd-1) compared with 0%DGP (148.04 gd-1) group. There were no differences in the enteric fluxes from 0%DGP and 5%DGP groups for CO2 (8854.04 g·d-1, 9322.69 g·d-1; P = 0.12), CH4 (139.75 g·d-1, 154.12 g·d-1; P = 0.29), O2 (6327.84 g·d-1, 9107.30 g·d-1; P = 0.27) and H2 (0.87 g·d-1, 0. g·d-1; P = 0.17). Results suggest that organosulfur compounds in dehydrated garlic powder can be stable and contributed to enhanced mineral supplement intake of feedlot cattle but did not affect enteric gas fluxes and body performance.

Effects of Fermented Oat Straw as a Lovastatin Carrier on in vitro Methane Production and Rumen Microbiota

To date, there is an urgent need for implementing practical strategies to reduce CH4 emissions from ruminants. Lovastatin (Lv) is a specific inhibitor of methanogenic archaea. Due to the high cost of pure Lv, solid-state fermentation might be an economical bioprocess to produce Lv and facilitate its use in ruminant nutrition. The goal of this work was to assess the effects of supplementing fermented oat straw as a lovastatin carrier (FOS) to a high-grain ration on in vitro CH4 inhibition and rumen microbiota in beef cattle. The experimental design of in vitro rumen fermentation was completely randomized with four concentrations of Lv in the diet mixture. The supplementation with FOS to give Lv concentration of 100 and 150 mg L−1 in the ruminal fermentation medium significantly inhibited methanogenesis at similar levels. This suggested that less than 20% of FOS was required in the ration to achieve up to 38% of CH4 mitigation without affecting the chemical composition and nutritional value of the ration. Short-chain fatty acid (SCFA) production and profile showed that only the treatments with Lv at 100 and 150 mg L−1 decreased the concentration of total SCFAs; the molar ratio of propionate significantly increased with respect to that of the control. Treatment with Lv at 150 mg L−1 did not result in significant differences in the alpha and beta diversity indices compared to the control. However, significant changes in the relative abundance of some microorganisms were detected, such as an increase in Ruminococcus and a decrease in Prevotella. The predominant 99%+ MA in all controls, treatment, and inocula samples belonged to the Methanobrevibacter genus and very small (negligible) unclassified Methanobacterium genus (Euryarchaeota phylum). Interestingly, the reduction of relative abundance of MA was 39.17%, very close to the percent reduction of CH4 production, 38%. Our data showed that there was a parallel and similar percent decrease of both CH4 production and relative abundance of the predominant MA in our experiment, although the statistical significance was not complete. Finally, our results hold promise for significantly decreasing ruminal CH4 by 38%. Thus, our work is one step toward the sustainable management of the livestock sector.

Is Grassfed Meat and Dairy Better for Human and Environmental Health?

The health of livestock, humans, and environments is tied to plant diversity—and associated phytochemical richness—across landscapes. Health is enhanced when livestock forage on phytochemically rich landscapes, is reduced when livestock forage on simple mixture or monoculture pastures or consume high-grain rations in feedlots, and is greatly reduced for people who eat highly processed diets. Circumstantial evidence supports the hypothesis that phytochemical richness of herbivore diets enhances biochemical richness of meat and dairy, which is linked with human and environmental health. Among many roles they play in health, phytochemicals in herbivore diets protect meat and dairy from protein oxidation and lipid peroxidation that cause low-grade systemic inflammation implicated in heart disease and cancer in humans. Yet, epidemiological and ecological studies critical of red meat consumption do not discriminate among meats from livestock fed high-grain rations as opposed to livestock foraging on landscapes of increasing phytochemical richness. The global shift away from phytochemically and biochemically rich wholesome foods to highly processed diets enabled 2.1 billion people to become overweight or obese and increased the incidence of type II diabetes, heart disease, and cancer. Unimpeded, these trends will add to a projected substantial increase in greenhouse gas emissions (GHGE) from producing food and clearing land by 2050. While agriculture contributes one quarter of GHGE, livestock can play a sizable role in climate mitigation. Of 80 ways to alleviate climate change, regenerative agriculture—managed grazing, silvopasture, tree intercropping, conservation agriculture, and farmland restoration—jointly rank number one as ways to sequester GHG. Mitigating the impacts of people in the Anthropocene can be enabled through diet to improve human and environmental health, but that will require profound changes in society. People will have to learn we are members of nature's communities. What we do to them, we do to ourselves. Only by nurturing them can we nurture ourselves.

反すう動物の第1胃内容液の粘度について : I.穀類飼料多給の影響

反すう動物の第1胃内容液の粘度について : I.穀類飼料多給の影響

Prevalence and molecular characterization of Escherichia coli O157:H7 by multiple-locus variable-number tandem repeat analysis and pulsed-field gel electrophoresis in three sheep farming operations in California.

A year-long study was conducted to determine the fecal prevalence of Escherichia coli O157:H7 in three sheep ranches. Strain diversity and persistence were compared with multiple-locus variable-number tandem repeat analysis and pulsed-field gel electrophoresis. Ranch C, a feedlot, consisted of young sheep raised predominantly on a high-grain diet. The other two sites consisted of sheep raised on native pasture and a combination of native and irrigated pasture. Forty fecal samples were collected every month from each ranch. Samples were examined for E. coli O157:H7 by immunomagnetic separation and culture of the magnetic beads onto selective media. Detection of virulence markers in positive isolates was determined by PCR. E. coli O157:H7 was isolated from 100 (22.7%) of 440 fecal samples collected from ranch C. On ranch B, 9 (1.9%) of the 480 fecal samples were positive for the pathogen, while none of the samples from ranch A were positive. On ranch C, the odds of detecting E. coli O157:H7 was 3.2 times greater during the warmer months compared with the cooler months of the year. There was no association between days spent in the feedlot and fecal prevalence of the pathogen (P = 0.62). Most multiple-locus variable-number tandem repeat analysis types were isolated only once from ranch C (14 of 23), but several strains were isolated over 4 to 6 months, often in many intervening negative months. This study revealed that the prevalence of E. coli O157:H7 can be high in some sheep ranches in California, especially in feedlots where young sheep are fed predominantly high-grain rations.

The effect of high grain versus all forage rations on plasma ghrelin level in sheep

Ghrelin, produced mainly in abomasum of ruminants, is a peptide with roles in the regulation of feeding. The present study assessed the alterations of plasma ghrelin in sheep fed with all forage or high-grain rations and the probable effects of altered ghrelin secretion on feed intake in animals with acidic rumen. Eight Karakul male lambs were divided into the control (n = 4) and experiment groups (n = 4) and fed individually for 20 days. The control group was fed an all forage ration for the whole study period. For the experiment group, 40% of the ration was substituted with ground barley for 10 days. For the rest of the study, 62.5% of the ration was substituted with ground barley. Signs of negative alteration of digestive functions (e.g., reduced feed intake, loose manure with reduced dry matter) were observed in the experiment group after day 10 of the experiment when ground barley was increased to 62.5% of the ration. On days 8 and 10 of each step, blood samples were collected for measuring plasma ghrelin level from jugular vein 1 hour before, and 1 and 3 hours after feeding. In the control group, plasma ghrelin increased 1 hour post-feeding (p < 0.05 in step 1) and decreased 3 hours post-feeding. In the experiment group, however, non-significant decreases were noticed in plasma ghrelin concentration 1 hour after feeding, followed by a sharp and significant rise 3 hours post-feeding (p < 0.05). Comparing the control and the experiment groups, we found that plasma ghrelin concentration was lower in the experiment group 1 hour post-feeding with significant difference (P = 0.002) in the second step. At 3 hours post-feeding, plasma ghrelin was higher in the experiment group with significant difference (P = 0.050) in the second step. In conclusion, ration composition may affect ghrelin secretion in sheep. High-grain rations and acidic condition of the rumen may increase ghrelin secretion within a few hours of feeding. This increase in ghrelin secretion, however, may not result in increased feed intake.

Supplementation with plant extracts (carvacrol, cinnamaldehyde and capsaicin): Its effects on acid-base status and productive performance in growing/finishing bull calves

This study investigated the in vivo effects of a commercial blend of plant extracts (carvacrol, cinnamaldehyde and capsaicin) on blood acid-base balance and serum lactate levels in a 148-day feedlot experimentwith 24 double-muscled Belgian Blue bull calves. Animals were allotted randomly to one of two experimental groups: 1) a control group (C, no supplementation; n = 10), and 2) a group receiving dietary supplementation with a combination of plant extracts (PE, 100 mg per kg DM of concentrate; n = 14). All animals received a high-grain ration, typical of diets fed commercially to feedlot cattle in Spain, consisting mainly of barley plus other components in proportions depending on the production phase. Production data (weight, DMI, ADG and feed-to-gain ratio) were recorded, and venous blood pH, pCO2, HCO3(-), Base Excess -BE- and serum L-lactate were determined. Apparently, beneficial effects of supplementation on production parameters were observed in both growing and finishing periods, though statistically significant effects were only observed in the finishing period. As regards blood parameters, no significant effects of supplementation (or the supplementation x time interaction) were observed, except for an effect on blood pH in the growing period, when supplemented animals showed significantly higher values than controls. A beneficial supplementation x time interactive effect was observed on serum L-lactate levels: from the first week of the study until the end, supplemented animals showed significantly lower levels than controls. These in vivo results support the utility of this dietary supplement in feedlot cattle receiving a barley-based high-grain diet.

Escherichia coli O157:H7 Populations in Sheep Can Be Reduced by Chlorate Supplementation

Ruminant animals are a natural reservoir of the foodborne pathogen Escherichia coli O157:H7. Some foodborne pathogens (e.g., E. coli) are equipped with a nitrate reductase that cometabolically reduces chlorate. The intracellular reduction of chlorate to chlorite kills nitrate reductase–positive bacteria; however, species that do not reduce nitrate are not affected by chlorate. Therefore, it has been suggested that ruminants be supplemented with chlorate prior to shipment for slaughter in order to reduce foodborne illnesses in human consumers. Sheep (n = 14) were fed a high-grain ration and were experimentally infected with E. coli O157:H7. These sheep were given an experimental product (XCP) containing the equivalent of either 2.5mM NaNO3 and 100mM NaCl (control sheep; n = 7) or 2.5mM NaNO3 and 100mM NaClO3 (chlorate [XCP]–treated sheep; n = 7). Control and XCP-treated sheep were treated for 24 h; XCP treatment reduced the population of inoculated E. coli O157:H7 (P < 0.05) from 102, 105, and 105 CFU/g in the rumen, cecum, and rectum, respectively, to <101 CFU/g in all three sections of the gastrointestinal tract. The number of sheep testing positive for E. coli O157:H7 was significantly reduced by XCP treatment. In a similar fashion, total E. coli and coliforms were also reduced (P < 0.05) in all three compartments of the intestinal tract. Intestinal pH, total volatile fatty acid production, and the acetate/propionate ratio were unaffected by XCP treatment. On the basis of these results, it appears that chlorate treatment can be an effective method for the reduction of E. coli O157:H7 populations in ruminant animals immediately prior to slaughter.

Effects of dietary undegradable crude protein level on total non-structural carbohydrate (TNC) digestibility, and milk yield and composition of dairy cows

This trial was designed to investigate whether increasing the amount of ruminal undegradable crude protein (CP) content of rations given to high producing dairy cows, affected total non-structural carbohydrate (TNC) digestibility and milk production. A total of 36 Israeli-Holstein multiparous dairy cows were assigned to three treatments according to parity number, calving date, milk yield during the previous lactation and body weight (BW) 2 days after calving. Diets were formulated to contain (on a DM basis) 45% forage, 16.5% CP, 1.7 Mcal/kg net energy lactation (NE), and differed in dietary CP undegradability, as follows: (1) low undegradable CP (LUDCP)-UDCP, 36% of dietary CP; (2) medium UDCP (MUDCP)-UDCP, 41% of dietary CP; and (3) high UDCP (HUDCP)-UDCP, 46% of dietary CP. Dietary UDCP was increased by reducing concentrations of soybean meal and urea and increasing those of fish meal and gluten meal. The cows were maintained in the trial for 3 months. Average dry matter intakes of cows on LUDCP, MUDCP and HUDCP treatments were 25.0, 23.3 and 23.3 kg/day, respectively ( P>0.1). Treatment averages of milk yield (kg/day), milk fat, protein and lactose (%) were 43.3, 3.01, 2.97 and 4.48, respectively, and no significant differences between diets were observed. Apparent digestibilities of dietary CP and TNC were increased by UDCP supplementation ( P<0.02 and P<0.0001, respectively). Differences in body condition score (BCS) between the beginning and the end of the experiment were −0.48, −0.17 and +0.03 units, respectively, in the cows fed the LUDCP, MUDCP and HUDCP rations ( P<0.005). A linear equation was fitted to describe the changes in BCS of the cows given the various treatments; its slope differed significantly among treatments ( P<0.0001). Plasma glucose concentrations were 51.7, 58.4 and 58.5 mg/100 ml, respectively, in the cows fed the LUDCP, MUDCP and HUDCP rations (Contrast<0.02). It was concluded that by increasing dietary UDCP up to 7.3%, starch digestion in the small intestine and dietary energy utilization efficiency of milking cows on high-grain rations were significantly improved.

Effect of ration and exercise on plasma creatine kinase activity and lactate concentration in Thoroughbred horses with recurrent exertional rhabdomyolysis.

To determine the effects of 3 rations (low grain, fat, high grain) on plasma creatine kinase (CK) activity and lactate concentration in Thoroughbred horses with recurrent exertional rhabdomyolysis (RER). 5 Thoroughbreds with RER and 3 healthy Thoroughbreds (control horses). Rations were formulated to meet (low-grain and fat rations) or exceed (high-grain ration) daily energy requirements. Each ration was fed to horses in a crossover design for 3 weeks. Horses were exercised on a treadmill Monday through Friday; maximum speed on Monday and Friday was 11 m/s (6% slope), on Tuesday and Thursday was 9 m/s, and on Wednesday was 4.5 m/s. Plasma CK activity and lactate concentration were determined before and after exercise. Horses with RER fed the high-grain ration had significantly greater CK activity and change in CK activity 4 hours after exercise, compared with those fed the low-grain ration. Horses with RER exercised at the trot or canter had significantly greater increases in CK activity, compared with those exercised at the gallop. Plasma lactate concentrations after exercise were similar in control and affected horses. Lactate concentration and CK activity were not correlated in horses with RER. Rations high in grain and formulated to exceed daily energy requirements may increase episodes of rhabdomyolysis in thoroughbred horses susceptible to RER.

Effects of Intraruminal Infusions of Mineral Salts on Volatile Fatty Acid Production in Steers Fed High-Grain and High-Roughage Diets

Four rumen fistulated Holstein steers were used to assess the effects of intraruminal salt infusions on various rumen characteristics including volatile fatty acid production rates. In the first experiment, the basal diet consisted of 75% concentrate and 25% corn silage (high-grain diet). The experimental design was a 4×4 Latin square in which the four treatments were: 1) intraruminal infusion of 8 liters of water (control) or 8 liters of water plus 2) 288g sodium bicarbonate, 3) 200g sodium chloride, or 4) 600g sodium chloride. In the second experiment, procedures were the same except the basal diet consisted of 64% alfalfa hay and 18% each of corn silage and concentrate (high-roughage diet). When the high-grain basal diet was fed, intraruminal infusions of mineral salts increased dilution rate of rumen fluid. Total fluid flow from the rumen also was increased by salt infusions with sodium bicarbonate and the most sodium chloride (600 g/day) exerting greatest effects for both dietary regimens. Salt infusions reduced the molar percentage of rumen propionate and increased the molar percentage of acetate when the high-grain diet was fed. These same treatments were without effect on molar percentages of rumen acids when the high-roughage diet was fed. The change in the molar percentages of acetate and propionate on the high-grain ration was solely from reduction in propionate production. The lower production of propionate, from salt infusions, may have occurred because of the washout of readily fermentable materials. Dry matter disappearance from feeds placed in dacron bags and suspended in the rumen was unaffected by infusion of mineral salts.

EFFECTS OF THREE PROTEIN LEVELS WITH AND WITHOUT ADDED FAT ON THE PERFORMANCE AND CARCASS CHARACTERISTICS OF HEAVY VEAL CALVES

Twenty-four Holstein bull calves were fed high concentrate rations containing 12, 15 or 18% crude protein (as fed basis), with or without 4% added tallow, from 12 wk of age (avg wt 85 kg) to 200 kg liveweight. Seven calves were removed from trial during the course of the experiment due to salmonellosis (1), bloat (3) and calcium or magnesum deficiency (3). Dietary protein level had no effect (P &lt; 0.05) on average daily gains, feed intake, or feed efficiency. Average daily gains were 1.02, 0.95 and 0.93 kg for 12, 15 and 18% protein diets, respectively. Calves fed 4% added tallow were more efficient in feed conversion than those fed no added tallow (adjusted mean difference of 0.43 ±.29 kg feed per kg gain, P &lt; 0.05). Increasing levels of dietary protein produced a significant linear increase in protein content (P &lt; 0.05) of meat samples. The addition of 4% dietary tallow increased the water, protein and fat content of bone samples and depressed ash. Taste panel ratings for flavor, tenderness and overall satisfaction were higher for calves that received no added tallow in their rations. Feed cost per kg gain was lowest for the ration containing 12% protein and 0% added fat. It was concluded that a 12% crude protein high-grain ration fed to calves from 12 wk to 200 kg resulted in performance comparable to 15 and 18% protein rations and that the only benefit from added fat was an improvement in feed efficiency.

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.

Influence of processing method on energy utilization of feed grains

A comparative slaughter-feeding trial technique was used to determine the influence of various steam-processing treatments on the energy utilization and feeding value of wheat, corn, barley and milo for feedlot cattle. Processing of wheat, corn and barley by various steam-pressure-time combinations did not consistently improve their value compared to processing by a standard steam-rolling procedure. Steam-pressure processing of milo resulted in a 10 per cent improvement in the net energy for gain value of high-grain rations. The optimum time-pressure steam treatment was approximately 1.5 ± .5 minutes at 3.5 ± .5 kg/cm2. The improvement in the feeding value of steam-pressure-processed milo seems to be due to small, but additive, beneficial effects associated with an improvement in energy digestibility, more rapid rumen fermentation, and decreased food intake.

Peptostreptococcus elsdenii from the caecum of pigs.

SUMMARY: Large, Gram-negative, anaerobic cocci (LC) fermenting lactate were first isolated by enrichment culture from the sheep rumen (Elsden, Volcani, Gilchrist &amp; Lewis, 1956). High counts (about 109/ml.) were obtained from young calves but not from adult ruminants by Hobson, Mann &amp; Oxford (1958). The cocci were cultured in numbers of 106 to 103/ml. from the rumen of cattle fed high-grain rations and named Peptostreptococcus elsdenii by Gutierrez, Davis, Lindahl &amp; Warwick (1959). They can be important fermenters of lactate in the rumen and are associated with amylolytic lactate producers such as Streptococcus bovis when large amounts of starch are consumed by ruminants. The production of propionic acid by P. elsdenii via the acrylate pathway (Ladd, 1959) has attracted the particular interest of biochemists and nutritionists. The types of bacteria active in the rumen are not found only in this organ (Giesecke, 1970), and recent experiments indicate that P. elsdenii is also a prominent lactate fermenter in the large intestine of pigs fed on diets containing potatoes.

Effect of Bentonite on Nitrogen and Mineral Balances and Ration Digestibility of High-Grain Rations Fed to Lactating Dairy Cows

A digestion trial was conducted with lactating Holstein cows fed the following rations: I) a high-grain, fat-depressing ration; II) fat-depressing ration + 5% sodium bentonite; and III) fat-depressing ration + 10% sodium bentonite.The mean adjusted dry matter digestibilities of I) 78.7%, II) 80.8%, and III) 76.5% were not significantly different. A nonsignificant increase in nitrogen retention with a significant decrease in crude protein digestibility was noted with both of the bentonite treatments. The mean protein digestibilities (%) and daily nitrogen retention (g/day) for the treatments were: I) 79.9 and 37.2; II) 75.4 and 75.9; and III) 68.8 and 53.0, respectively. Energy digestibility decreased significantly. Mean digestible energy (%) for Treatments I, II, and III were 78.4, 71.8, and 69.1. Calcium, phosphorus, and magnesium balances (g/day) were as follows: I) 31.6, 33.0, 8.2; II) 9.5, 9.4, 2.1; and III) 3.1, -3.4, 1.5. Differences between I versus II and III as well as II versus III in phosphorus balance were statistically significant.

PROPORTIONS OF MAJOR BOVINE TISSUES AS INFLUENCED BY RATIONS BASED ON BARLEY OR OATS

The experiment was conducted to study the effect of oats and barley in high-grain rations on performance of calves and on totals and proportions of muscle, bone and fat in the carcasses. Each experimental diet was fed to a group of four Jersey bull calves. There was no significant difference between the two groups of calves in average daily liveweight gain, and very little difference in feed conversion efficiency and daily feed consumption.On the basis of total dissection of one-half of each carcass, calves fed barley contained practically the same amount of lean, similar proportions of bone and more fat (23.6% vs. 14.9%) compared with those fed oats. Barley-fed animals consumed 26.3% more digestible energy over maintenance requirements than oats-fed animals. This resulted in 58.4% more dissectable fat in the carcasses of barley-fed animals.

Manipulation of the Ruminal Fermentation. II. Effect of Sodium Sulfite on Bovine Digestion and Ruminal Fermentation

In previous work, sodium sulfite was used to manipulate the ruminal fermentation by decreasing the molar per cent acetate and increasing that of propionate and butyrate in lactating cows. In this study the effects of sodium sulfite on ruminal fermentation were studied further, along with its effect on ration digestibility. No effect of sodium sulfite on the digestibility of a high-grain ration fed to steers was observed. However, feed intake on the sulfite diets was variable. In studies with incubated ruminal ingesta, acetate production decreased, whereas the more highly reduced acids were generally increased. Gas production by ruminal ingesta from a cow on a hay diet and another cow on a hay-grain diet was measured with and without sodium sulfite added to the ingesta. Methane production was decreased (P<0.01) on both types of ingesta by the addition of sulfite. The ratio of carbon dioxide to methane was widened (P<0.05) from 1.98 with the control hay ingesta to 4.49 with the hay ingesta with 75mg of sodium sulfite added per 100ml of ingesta. The ratio of carbon dioxide to methane was widened (P<0.05) from 2.55 with control hay-grain ingesta to 5.75 with the hay-grain ingesta with 100mg of Na2SO3 added per 100ml of ingesta.

Additive Nature of Sodium Bicarbonate and Magnesium Oxide on Milk Fat Concentrations of Milking Cows Fed Restricted-Roughage Rations

Sodium bicarbonate (272 or 363 g/day) and MgO (136 or 181 g/day) alone or combined were added to the diet of 20 cows given a low-roughage–high-grain ration in a Latin-square trial. Responses were the same for the second, third, and fourth weeks of each four-week period. Both supplements increased fat test and rumen pH, but decreased molar proportion of valerate and propionate in the rumen. These effects were additive when both were fed together. Sodium bicarbonate increased daily milk and fat production, but MgO caused a slight decrease, probably due to its more pronounced effect on decreasing grain intake. Cows with the greatest level of milk and fat production had the greatest mammary uptake of glucose and acetate. Mammary uptake of plasma glucose, acetate, cholesterol, cholesterol esters, and triglycerides were positively related to arterial concentrations. Simple and multiple correlation coefficients indicated that milk fat concentration was negatively related to rumen valerate and propionate proportions, but when supplements were fed valerate assumed much more importance than propionate. The extent and sign (− or +) of several coefficients changed when MgO was fed.