Subacute ruminal acidosis induces ruminal lipopolysaccharide endotoxin release and triggers an inflammatory response

Subacute ruminal acidosis (SARA) was induced in 3 rumen fistulated Jersey steers by offering them different combinations of wheat-barley pellets and chopped alfalfa hay. Steers were offered 4, 5, and 6 kg/d of pelleted concentrate and 6, 5, and 4 kg/d of chopped alfalfa hay for diets 1, 2, and 3, respectively, during 5-d treatment periods and were fed chopped alfalfa hay between treatment periods. Inducing SARA increased blood concentrations of haptoglobin and serum amyloid-A. Dry matter intake of concentrate and hay decreased from d 1 to 5 in each period. Subacute ruminal acidosis was induced in all steers during d 4 and 5 when concentrate was fed, with ruminal pH remaining below 5.6 for an average of 187 and 174 min/d on these days. Lipopolysaccharide concentration increased significantly during periods of grain feeding compared with times when only hay was fed. Inducing SARA by feeding wheat-barley pellets activated a systemic inflammatory response in the steers.     

Nutrient digestion in the large intestine as influenced by forage to concentrate ratio and forage physical form

Digestion in the large intestine was investigated in four growing steers fitted with duodenal and ileal cannulas. Diets assigned within a 4 x 4 Latin square were: 20% long alfalfa hay and 80% grain; 15% pelleted alfalfa, 5% hay, and 80% grain; 80% hay and 20% grain; and 60% pellets, 20% hay, and 20% grain. Intake of DM was not affected by diet. Organic matter digestion in the large intestine averaged 9, 3, 1, and -4% of total tract digestion for the 20% hay, 20% pellet, 80% hay, and 80% pellet diets, respectively, with significant increases due to high grain diets and long hay. Digestion of CP in the large intestine as a percentage of total tract digestion was unaffected by diet but averaged 3, -1, .3, and -6% for the respective diets. Percentage of total tract starch digestion occurring in the large intestine increased with grain feeding and averaged 6, 3, 1, and 1%, respectively. Digestion of ADF and NDF in the large intestine as a percentage of total tract was unaffected by diet; however, the respective means were 16 and 15, 7 and 7, 5 and 15, and 1 and 1%. In a second trail the same animals were fed a more typical dairy cow diet consisting of 50% grain, 25% corn silage, and 25% long alfalfa hay for a single 18-d period. Digestion in the large intestine accounted for 2.1, .2, 3.6, and 6.4% of total tract digestion of organic matter, starch, ADF, and NDF, respectively; however, feed intake was not as great as in the first trail. Although conditions of these studies differed from those commonly experienced by lactating cows, the underlying principals should apply. The large intestine would be expected to make an even greater contribution to total tract digestion in lactating cows consuming proportionally more DM.     

Forage type influences milk yield and ruminal responses to wheat adaptation in late-lactation dairy cows

The effects of different wheat adaptation strategies on ruminal fluid pH, dry matter intake (DMI) and energy-corrected milk (ECM) were measured in 28 late-lactation dairy cows. Cows were fed either perennial ryegrass (PRG) hay or alfalfa hay and had no previous wheat adaptation. Wheat was gradually substituted for forage in 3 even increments, over 6 or 11 d, until wheat made up 40% of DMI (～8 kg of dry matter/cow per day). We found no differences in DMI between adaptation strategies (6 or 11 d) within forage type; however, cows fed alfalfa hay consumed more overall and produced more ECM. The rate of ruminal pH decline after feeding, as well as the decrease in mean, minimum, and maximum ruminal pH with every additional kilogram of wheat was greater for cows fed alfalfa hay. Cows fed alfalfa hay and on the 6-d adaptation strategy had the lowest mean and minimum ruminal fluid pH on 3 consecutive days and were the only treatment group to record pH values below 6.0. Despite ruminal pH declining to levels typically considered low, no other measured parameters indicated compromised fermentation or acidosis. Rather, cows fed alfalfa hay and adapted to wheat over 6 d had greater ECM yields than cows on the 11-d strategy. This was due to the 6-d adaptation strategy increasing the metabolizable energy intake in a shorter period than the 11-d strategy, as substituting wheat for alfalfa hay caused a substantial increase in the metabolizable energy concentration of the diet. We found no difference in ECM between adaptation strategies when PRG hay was fed, as there was no difference in metabolizable energy intake. The higher metabolizable energy concentration and lower intake of the PRG hay meant the increase in metabolizable energy intake with the substitution of wheat was less pronounced for cows consuming PRG hay compared with alfalfa hay. Neither forage type nor adaptation strategy affected time spent ruminating. The higher intakes likely contributed to the lower ruminal pH values from the alfalfa hay treatments. However, both forages allowed the rumen contents to resist the large declines in ruminal pH typically seen during rapid grain adaptation. Depending on the choice of base forage, rapid grain introduction may not result in poor adaptation. In situations where high-energy grains are substituted for a low-energy, high-fiber basal forage, rapid introduction could prove beneficial over gradual strategies.     

Effects of sampling site on passage rate estimates in heifers fed alfalfa hay or a high concentrate diet

Rate of passage from the rumen was estimated from samples from the rumen, duodenum, ileum, and rectum after four crossbred heifers were dosed with cobalt ethylenediaminetetraacetic acid and ytterbium-labeled alfalfa or corn grain as digesta markers. Diets consisted of chopped alfalfa hay or an 80% concentrate mixture fed twice daily at 2.0% of body weight (dry matter per day) in two trials. Rates of particulate passage were calculated by two mathematical models, and influence of site of sampling on rate of ruminal passage was appraised. Rate of fluid passage calculated from ruminal samples was more rapid than rates from samples at the duodenum, ileum, and rectum for both the alfalfa diet (10.6 versus 6.3, 5.6, and 5.6% X h-1) and the 80% concentrate diet (10.3 versus 6.8, 7.2, and 6.1% X h-1). With the alfalfa diet, rates of fluid passage estimated from ruminal and rectal samples were correlated .98 despite the marked disparity of means. Rates of passage of particulates estimated from samples from the duodenum, ileum, and rectum were not correlated. Estimates of rate of digesta passage from the rumen differed with postruminal site of sampling.     

Effects of feed intake and dietary urea concentration on ruminal dilution rate and efficiency of bacterial growth in steers

Four multiple-fistulated steers (340 kg) were fed a diet containing 50% ground grass hay, 20% dry distillers grains, and 30% concentrate at two intakes (7.2 or 4.8 kg DM/d). Urea (.4 or 1.2% of the diet) was infused continuously into the steers' rumens. The experimental design was a 4 X 4 Latin square with a 2 X 2 factorial arrangement of treatments. Infusing urea at .4 or 1.2% of the diet resulted in ruminal NH3 N concentrations of 4.97 and 9.10 mg/dl, respectively. Feeding steers at high rather than low intake decreased ruminal and total tract digestibilities of organic matter, NDF, and ADF but did not increase ruminal escape of N. However, apparent N escape from the rumen calculated using purines, but not 15N, as a bacterial marker was higher when 1.2 vs. .4% urea was infused. Feeding at high rather than at low intake increased the total pool of viable bacteria per gram organic matter fermented in the rumen. Although ruminal fluid outflows and particulate dilution rates were greater when steers were fed at high than at low intakes, efficiencies of bacterial protein synthesis were unaffected by intake. The possibility of increased N recycling within the rumen with feeding at the higher intake is discussed.     

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 X 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) 288 g sodium bicarbonate, 3) 200 g sodium chloride, or 4) 600 g 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 from (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.     

Influence of feed intake, forage physical form, and forage fiber content on particle size of masticated forage, ruminal digesta, and feces of dairy cows

Two trials were conducted to determine particle size of masticates, ruminal digesta, and feces of dairy cows. In Trial 1, three Holstein cows with ruminal cannulae were fed prebloom alfalfa hay in long, chopped, or pelleted form in a Latin square design (21-d periods) conducted in early lactation (wk 3 to 11) and again during the dry period to attain high (3.75) and low (1.95% of BW) feed consumption. In trial 2, prebloom, midbloom, and full bloom alfalfa hay, mature bromegrass hay, and corn silage were fed to early lactation (wk 5 to 15) Holsteins in a 5 X 5 Latin square design (15-d periods). All diets (Trials 1 and 2) were formulated to 17% CP and contained forage:grain in a 60:40 ratio (DM basis). Similar particle distributions of digesta from long and chopped hay diets suggest little influence of chopping forage on particle size reduction when high quality forage is fed. The large proportion of DM in the small particle (less than .6 mm) pool in the rumen in both trials suggests that rate of escape of small particles from the rumen is an important factor influencing ruminal retention time. Increased proportion of coarse (greater than or equal to 2.36-mm screen) fecal particles at high intake and with fine grinding appears related to a reduction in chewing per unit feed consumed. Soluble DM and particulate matter passing a .063-mm screen made up a significant portion (30 to 50%) of the total DM sieved from all sampling sites in both trials.     

Feeding lactose increases ruminal butyrate and plasma beta-hydroxybutyrate in lactating dairy cows

Ruminal fermentation of lactose increases molar proportions of butyrate, which is metabolized by the ruminal epithelium to beta-hydroxybutyrate (BHBA). To determine the effects of dietary whey, and specifically lactose, on concentrations of ruminal and blood volatile fatty acids (VFA) and blood BHBA, 8 Holstein and 4 Brown Swiss multiparous cows (210 +/- 33 d in milk) were blocked by breed and randomly assigned to one of three 4 x 4 Latin squares. Treatments were control (CON; 7.1% of dietary dry matter [DM] as cornstarch), liquid whey (WHEY; 9.4% of diet DM) containing 70% lactose on a DM basis, low lactose (LOLAC; 7.1% lactose), or high lactose (HILAC; 14.3% lactose). Diets contained 53% forage as corn silage, alfalfa hay, and grass hay (DM basis) and a corn and soybean meal-based concentrate. Average dietary percentage of crude protein and energy density (Mcal/kg net energy for lactation) were 16.8 and 1.47, respectively. Feeding lactose increased DM intake. Milk production and composition were not affected by diet with the exception of decreased urea nitrogen in milk from cows fed lactose. Greater proportions of ruminal propionate were observed in cows fed CON relative to those fed WHEY and LOLAC. Increasing dietary lactose increased proportions of ruminal butyrate and decreased acetate and branched-chain VFA. Concurrent with the increase in ruminal butyrate concentrations, there was an increase in plasma BHBA as lactose in the diet increased. Concentrations of VFA in plasma were not affected by diet with the exception of the branched-chain VFA, which were increased in cows fed LOLAC compared with WHEY. These data indicate lactose fermentation increases proportions of ruminal butyrate and plasma BHBA in lactating dairy cows; however, the observed increase in plasma BHBA is not sufficient to subject cows to ketosis.     

Effects of fumarate on ruminal ammonia accumulation and fiber digestion in vitro and nutrient utilization in dairy does

The objective of this study was to evaluate effects of fumarate on ruminal ammonia accumulation and fiber digestion in vitro and on feed intake and nutrient utilization in dairy does. Batch cultures of mixed rumen microorganisms were used to study effects of different concentrations of fumarate on fermentation with various N sources (ammonia as ammonium bicarbonate, casein amino acids, casein peptides, gelatin peptides) and feeds (bermudagrass hay, mixed diet of 60% bermudagrass hay plus 40% concentrate) for 6 and 24 h, respectively. Substrates were grouped into pairs for separate incubations. Monosodium fumarate was added to incubation tubes to achieve final concentrations of 0, 5, and 10 mM fumarate. More ammonia accumulated at the end of incubation with added ammonium bicarbonate. Ammonia concentration was higher for peptide compared with amino acid incubation, and for casein peptide compared with gelatin peptide. Addition of fumarate linearly decreased ammonia for all N sources and for feed substrates. For all substrate types, fumarate treatment increased acetate, propionate, and total volatile fatty acids (VFA), decreased acetate to propionate ratio, and tended to reduce branched-chain VFA. Digestion of feed neutral detergent fiber (NDF) by rumen microorganisms was improved by fumarate along with elevated endoglucanase and xylanase activities. In an animal metabolism experiment, 8 dairy does (4 per treatment) were used in a completely randomized design for 21 d. Does were fed a hay plus concentrate diet without (control) or with fumarate (6 g/head per day) supplementation to determine feed intake, whole-tract nutrient digestibility, and N utilization. Fumarate treatment did not affect weight change or feed intake but increased whole-tract digestion of gross energy, crude protein, and cellulose. Digested N was increased by fumarate supplementation; however, N retention was unaffected. Plasma glucose concentration was elevated with fumarate but urea N concentration remained unchanged. Fumarate addition had significant effects on rumen microbial fermentation by decreasing ammonia and branched-chain VFA, and by increasing acetate and propionate, and NDF digestion. These effects were reflected in the improvement in whole-tract gross energy, crude protein, and cellulose digestion and elevated plasma glucose concentration when dairy does were supplemented with fumarate.     

Sodium bicarbonate and alfalfa hay additions to wheat silage diets fed to lactating dairy cows

Two experiments were conducted to examine dietary effects of .8% sodium bicarbonate and 1.4 kg/d of alfalfa hay on performance and rumen metabolism of lactating dairy cows fed 50% wheat silage and 50% concentrate (dry basis). In Experiment 1 with 12 midlactation Holsteins in a 4 X 4 Latin square design, intake, milk production, and milk composition were not affected by treatment. Dietary sodium bicarbonate and alfalfa hay did not alter blood, rumen, or fecal pH. Rumen volatile fatty acid pattern was not affected by sodium bicarbonate, but addition of hay resulted in higher molar percentage propionate and lower acetate: propionate ratios. In Experiment 2 with 32 early lactation cows (20 Holsteins and 12 Jerseys) in a complete randomized block design, supplementation of sodium bicarbonate, alfalfa hay, or both did not affect intake, milk production, or milk composition in the first 8 wk of lactation. Blood, rumen, and fecal pH were not affected by treatment. Dietary sodium bicarbonate did not alter ruminal volatile fatty acid profile, whereas addition of hay increased molar proportion acetate and decreased molar proportion butyrate. A shift in rumen fermentation was observed across treatments from wk 1 through 8 postpartum with molar proportions of acetate and butyrate increasing and molar proportion of propionate decreasing.     

Effects of grain, fructose, and histidine on ruminal pH and fermentation products during an induced subacute acidosis protocol

The effects of grain, fructose, and histidine on ruminal pH and fermentation products were studied in dairy cattle during an induced subacute acidosis protocol. Thirty Holstein heifers were randomly allocated to 5 treatment groups: (1) control (no grain); (2) grain [fed at a crushed triticale dry matter intake (DMI) of 1.2% of body weight (BW)]; (3) grain (0.8% of BW DMI)+fructose (0.4% of BW DMI); (4) grain (1.2% of BW DMI)+histidine (6 g/head); and (5) grain (0.8% of BW DMI)+fructose (0.4% of BW DMI)+histidine (6 g/head) in a partial factorial arrangement. Heifers were fed 1 kg of grain daily with ad libitum access to ryegrass silage and alfalfa hay for 10 d. Feed was withheld for 14 h before challenge day, on which heifers were fed 200 g of alfalfa hay and then the treatment diets immediately thereafter. Rumen samples were collected 5 min after diet ingestion, 60 min later, and at 3 subsequent 50-min intervals. Grain decreased ruminal pH and increased ammonia, total volatile fatty acid (VFA), acetate, butyrate, propionate, and valerate concentrations compared with controls. The addition of grain had no effect on ruminal D- and L-lactate concentrations. Fructose markedly decreased ruminal pH and markedly increased D- and L-lactate concentrations. Fructose increased total VFA and butyrate and decreased valerate concentrations. Although histidine did not have a marked effect on ruminal fermentation, increased concentrations of histamine were observed following feeding. This study demonstrates that the substitution of some grain for fructose can lower ruminal pH and increase VFA and lactate concentrations, warranting further investigation into the role of sugars on the risk of acidosis in dairy cattle.     

Impact of forage fiber content on digestion and digesta passage in lactating dairy cows

Five Holstein cows (5 wk postpartum) were used in a Latin square design (15-d periods) to determine rumen fill and fractional rates of ruminal digestion and passage. Treatments consisted of prebloom, midbloom, and full bloom alfalfa hay, mature bromegrass hay, and corn silage fed in diets containing forage: concentrate in a 60:40 ratio (DM basis) formulated to be isonitrogenous. Intake of DM averaged 4.0% of body weight for prebloom alfalfa and corn silage. Milk yield and DM intake were lower for full bloom alfalfa and bromegrass than for prebloom alfalfa. Digestibility of organic matter was 7.5 percentage units lower for full bloom than for prebloom alfalfa. Weight of DM in the rumen was higher for midbloom and full bloom alfalfa and bromegrass than with prebloom alfalfa. Ruminal retention time of Yb applied to forage was longer for bromegrass than for prebloom alfalfa. Fractional rates of in situ NDF digestion were slower for full bloom alfalfa and bromegrass than for prebloom alfalfa. Results suggest that the point of limitation of feed intake due to gut fill is dependent on forage quality as well as energy demand of the animal. Dry matter fill of the rumen was more closely related to rates of ruminal digestion and passage than to total tract digestibility or maximum digestibility after lengthy in situ fermentation.     

Digestion of feed amino acids in the rumen and intestine of steers measured using a mobile nylon bag technique

The disappearance of dry matter (DM), crude protein (CP), and amino acids (AA) in steers after rumen incubation and intestinal passage of alfalfa hay, barley hay, corn silage, barley grain, corn grain, wheat bran, meat meal, fish meal, cottonseed meal, and soybean meal were measured in 3 steers using a mobile nylon bag technique. Ruminal degradation of individual AA differed between feedstuffs. For barley hay and corn silage, the ruminal disappearance of total AA was higher and lower than the other feedstuffs, respectively. The intestinal digestibility of total AA in alfalfa hay was lower than the digestion of CP. The intestinal digestibility of Arg and His was higher than that of total AA in alfalfa hay, meat meal, cottonseed meal, soybean meal, barley hay, and wheat bran. In addition, the intestinal digestibility of Lys was higher than that of total AA in alfalfa hay, meat meal, cottonseed meal, soybean meal, barley hay, corn silage, and wheat bran. The intestinal disappearance of CP in most cases was higher than that of DM. The results indicated that feedstuffs with lower ruminal disappearance of DM, CP, total AA, essential AA, and nonessential AA generally had a higher intestinal disappearance, resulting in a relatively constant total tract disappearance. These results could be used to improve the current system of diet formulation in ruminants.     

Milk production, nutrient digestion, and rate of digesta passage in dairy cows fed long or chopped alfalfa hay supplemented with sodium bicarbonate

Effects of forage particle size and sodium bicarbonate on milk production, ruminal fermentation, ruminal fluid dilution rate, dry matter passage from the rumen, and nutrient digestion were measured in four Holstein cows in a 4 X 4 Latin-square experiment. Cows were fed ad libitum amounts of a diet of approximately 46% concentrate and 54% alfalfa hay. The 2 X 2 factorial arrangement of treatments were: 1) long stem alfalfa hay, 2) long stem alfalfa hay + 1.4% sodium bicarbonate (3.0% of concentrate), 3) chopped alfalfa hay (1.3 cm), and 4) chopped alfalfa hay + 1.4% sodium bicarbonate. Feed intake, milk yield, and milk composition were similar among treatments. Ruminal pH and concentration and molar percentages of volatile fatty acids were not altered. Decreasing feed particle size reduced ruminal fluid outflow as estimated by polyethylene glycol and chromium ethylenediamine tetraacetic acid dilution rates. Digestion of nutrients was decreased with chopped alfalfa hay but was not related to faster rate of passage of smaller size feed particles as determined by rare earth markers. Sodium bicarbonate increased water intake and tended to improve nutrient digestion. Absence of a significant effect of sodium bicarbonate upon rate of passage of chopped hay indicates that feed particles of this size are not significantly affected by small increases of dilution rate of ruminal fluid. Addition of sodium bicarbonate to an alfalfa hay (forage)-based diet did not improve production responses but did increase nutrient digestion.     

Changes in fermentation profile of the reticulorumen and hindgut,and nutrient digestion in dry cows fed concentrate-rich diets supplemented with a phytogenic feed additive

This study evaluated the effects of duration of high-concentrate feeding on ruminal and fecal fermentation profile, as well as selected systemic health biomarkers in nonlactating cows supplemented with or without a phytogenic feed additive (PHY). In addition, ruminal degradation kinetics and total-tract nutrient digestibility were evaluated when feeding either only forage or a high-concentrate diet. Nine nonlactating, cannulated Holstein cows were used in a crossover design. Each period included 1 wk of forage feeding (wk 0), diet transition, and 4 wk on the high-concentrate diet (1, 2, 3 and wk 4; 65% dry matter basis). Cows received PHY or not (control). Compared with wk 0, from wk 1 onward, cows on high concentrate showed greater reticular, ruminal, and fecal total volatile fatty acids (VFA), with a greater level of VFA in the rumen than in the hindgut. However, ruminal fermentation was modulated differently by PHY, which showed increased total VFA in wk 1 and increased butyrate in wk 2 in the particle-associated fluid of rumen. In the hindgut, PHY increased propionate in wk 3. Cows fed a high-concentrate diet from wk 1 and onward also showed greater ruminal lactate, as well as lower ruminal and fecal pH, independent of PHY. In addition, compared with cows in wk 1 on a high-concentrate diet, cows in wk 4 had a greater total VFA in free fluid of the rumen and lower fecal pH. Compared with cows at wk 0, cows at wk 1 on high concentrate onward showed greater serum amyloid A and greater activity of glutamate dehydrogenase. In contrast, the high-concentrate diet decreased in situ ruminal degradability of grass silage but increased degradability of corn grain as well as total-tract nutrient digestibility, with total-tract neutral detergent fiber digestibility being greater for cows on the PHY treatment. Overall, from the start of high-concentrate feeding, gut fermentation increased, but differently according to location or PHY, with a stronger build-up of VFA in the rumen compared with the hindgut. In addition, a longer duration on high concentrate exacerbated gut acidification. The enhancing effects of PHY on total VFA and butyrate in particle-associated fluid of the rumen suggest beneficial effects of PHY on particle-associated bacteria, likely contributing to the increased neutral detergent fiber digestibility. The greater production of ruminal butyrate with PHY may be beneficial for the host, given the health benefits of this acid, but more research is needed to elucidate the effects on gut microbiota and the effects of increased butyrate in nonlactating dairy cows.     

Forage intake, ruminal dry matter disappearance, and ruminal blood volatile fatty acids for steers in 18 and 32 degrees C temperatures

Six steers with rumen cannulas and exteriorized carotid arteries were fed chopped alfalfa, orchardgrass, or tall fescue hay in ambient temperatures (18 and 32 degrees C) using a factorial arrangement of forage and temperature with repeated measurements. Arterial blood, venous blood, and rumen fluid were sampled for VFA at 0, 2, 4, and 7 h after forage was offered. Rate of digestion of plant cell wall was determined by in vitro methods. Rate of ingesta and particulate passage was determined by 144Ce marker. Volatile fatty acid concentrations in blood plasma and rumen fluid were not related to forage voluntary intake. Voluntary forage intake was related to calculated ruminal disappearance of cell wall (r2 of .94). Elevated ambient temperature, 32 degrees C, depressed voluntary forage intake but did not increase ruminal or blood VFA concentrations.     

Ration digestibilities and ruminal characteristics in steers fed chickpeas

Twenty-four Holstein steers were used in a 5-d digestion trial to evaluate chickpeas as a substitute for corn and soybean meal. Total mixed diets contained (dry basis) 51% concentrate mix, 33% corn silage, and 16% alfalfa hay. Concentrate mixes contained 0, 50, and 100% chickpeas in place of corn and soybean meal. Ad libitum intakes of DM were not different between diets. Digestibilities of DM, NDF, ADF, hemicellulose, cellulose, lignin, and gross energy were not different among diets. Digestibilities of protein, fat, and ash were greater for steers fed 100% chickpeas than 0% chickpeas. Fecal N was lower and absorbed N was higher for steers fed 100% chickpeas. Ruminal acetate and acetate:propionate ratio were lower and ruminal propionate was higher for all steers fed diets containing chickpeas. Ruminal ammonia and pH were similar for all treatments.     

Effect of lasalocid on performance of lactating dairy cows

Thirty-two midlactation dairy cows were fed either a typical dairy diet or the same diet plus 340 mg lasalocid/d for 98 d. Diets were 65% forage (alfalfa and corn silage) and 35% concentrate (DM basis). Lasalocid did not affect production of milk (21 kg/d) or FCM (20 kg/d) or milk composition. Dry matter intake was slightly lower for cows consuming lasalocid than for control cows (19.6 vs. 20.6 kg/d). Lasalocid improved energetic efficiency by about 20% during the first 2 wk of the experiment, but treatment effects diminished as the experiment progressed. The period in which lasalocid had significant effects on energetic efficiency was also the period in which lasalocid increased ruminal propionate and decreased ruminal acetate concentrations. On d 7 of the experiment, cows fed lasalocid had lower acetate to propionate ratios as compared with control (3.0:1 vs. 3.7:1). No effect of treatment was observed on ruminal VFA during the remainder of the experiment. These data are interpreted to show that lasalocid improved the efficiency of converting dietary digestible energy into NE1 by altering ruminal fermentation, but this effect was relatively short-lived, since treatment effects on ruminal VFA patterns and energetic efficiency became negligible by 28 d.     

Interactions of alfalfa hay and sodium propionate on dairy calf performance and rumen development

The objective of this experiment was to investigate the effects of different levels of alfalfa hay (AH) and sodium propionate (Pro) added to starter diets of Holstein calves on growth performance, rumen fermentation characteristics, and rumen development. Forty-two male Holstein calves (40 ± 2 kg of birth weight) were used in a complete randomized design with a 3 × 2 factorial arrangement of treatments. Dietary treatments were as follows: (1) control = concentrate only; (2) Pro = concentrate with 5% sodium propionate [dry matter (DM) basis]; (3) 5% AH = concentrate + 5% alfalfa hay (DM basis); (4) 5% AH + Pro = concentrate + 5% alfalfa hay + 5% sodium propionate (DM basis); (5) 10% AH = concentrate + 10% alfalfa hay (DM basis); and (6) 10% AH + Pro = concentrate + 10% alfalfa hay + 5% sodium propionate (DM basis). All calves were housed in individual pens bedded with sawdust until 10 wk of age. They were given ad libitum access to water and starter throughout the experiment and were fed 2 L of milk twice daily. Dry matter intake was recorded daily and body weight weekly. Calves from the control, 10% AH, and 10% AH + Pro treatments were euthanized after wk 10, and rumen wall samples were collected. Feeding of forage was found to increase overall dry matter intake, average daily gain, and final weight; supplementing sodium propionate had no effect on these parameters. Calves consuming forage had lower feed efficiency than those on the Pro diet. Rumen fluid in calves consuming forage had higher pH and greater concentrations of total volatile fatty acids and molar acetate. Morphometric parameters of the rumen wall substantiated the effect of AH supplementation, as plaque formation decreased macroscopically. Overall, the interaction between forage and sodium propionate did not affect calf performance parameters measured at the end of the experiment. Furthermore, inclusion of AH in starter diets positively enhanced the growth performance of male Holstein calves and influenced both the macroscopic and microscopic appearances of the rumen wall. These benefits, however, were small when only sodium propionate was offered.