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PubMed1990

Effect of dietary level of barley-based supplements and ruminal buffer on digestion and growth by beef cattle.

Six ruminally cannulated beef steers were used in a 6 x 6 Latin square experiment with a 3 x 2 factorial arrangement of treatments to evaluate the effects of barley supplementation (BS; 10, 30 or 50% of diet DM) and ruminal buffer (RB; Na sesquicarbonate at 0 or 4% of BS DM) addition to bromegrass hay-based diets on digestion. When early- (boot) and late- (full maturity) havested bromegrass and wheat straw substrates were incubated in situ, no interactions (P greater than .10) involving substrate with dietary BS or RB were observed, indicating that forages differing in fermentability responded similarly to different ruminal environments. Averaged across substrates, RB had no effect with 10% BS and a positive effect with 30% BS, but a negative effect with 50% BS diets (BS x RB, quadratic; P less than .05) for in situ DM and NDF disappearance for 18 and 24 h of incubation and for rate of disappearance of potentially degraded DM and NDF. Intakes of DM and digested DM were greater (P less than .01) for RB diets; however, RB had no effect (P greater than .10) on total tract DM and NDF digestibility. Intake and digestibility of DM increased linearly (P less than .01), whereas NDF digestibility decreased linearly (P less than .01) as BS percentage was increased in the diet. Sixty beef steers (avg initial wt 302 kg) were fed the same dietary treatments in a growth experiment. A numerical improvement in DM intake (P = .20) and ADG (P = .06) was observed when RB was provided with the 50% BS diet. Results of these experiments indicate that RB may moderate negative effects occurring on ruminal fiber digestion when grains are used to supplement forage-based diets; however, improvements in ruminal digestion were not translated effectively to improved animal productivity.

Ammonia↗

PubMed1990

The effects of lysocellin and varying calcium levels on performance and ruminal and plasma characteristics of growing beef steers fed corn silage.

Twenty-four steers initially averaging 221 kg BW were used to evaluate the effects of lysocellin and calcium (Ca) level on performance and ruminal and plasma characteristics. Lysocellin at 0 or 22 mg/kg of diet and Ca at .3 or .6% were fed in a 2 X 2 factorial arrangement of treatments. Steers in individual pens had ad libitum access to a diet consisting of 80% corn silage and 20% (DM basis) of a protein, mineral and vitamin supplement. Ruminal fluid and blood samples were collected on d 42 and 85 of the 113-d trial. Steers fed the .6% Ca diet gained faster and required less feed/unit of gain than those fed the .3% Ca diet (P less than .05). There was a tendency for a lysocellin X Ca interaction for gain and feed efficiency (P less than .10). Lysocellin tended to depress performance when fed with .3% Ca, but it tended to improve gain and feed efficiency when fed with .6% Ca. Molar proportions of propionate were higher and those of acetate were lower (P less than .01) for steers fed lysocellin. Ruminal-soluble Zn, Fe and Cu levels were higher (P less than .01) in steers fed lysocellin. Ruminal-soluble Ca (P less than .01) was higher and ruminal-soluble P and Na were lower (P less than .01) in steers fed .6% Ca. Plasma K was higher (P less than .05) in steers fed .6% Ca but it was lower (P less than .05) in steers fed lysocellin. Results of this study indicate that dietary Ca affects certain metabolic responses to lysocellin in growing cattle.

Animals↗

PubMed1990

Effects of increasing dietary levels of endophyte-infected tall fescue seed on diet digestibility and ruminal kinetics in sheep.

Three experiments were conducted with sheep to determine the effects of 1) increasing the dietary concentration of ergovaline and 2) environmental temperature on site of nutrient digestion and ruminal passage rates. Dietary ergovaline concentration, a measure of endophyte-alkaloid concentration, was modified by substituting ergovaline-infected for noninfected tall fescue seed. Ruminal and total tract OM, NDF and cellulose digestibilities were less (P less than .10) and ruminal fluid dilution rate (%/h) and fluid outflow (liters/h) were greater (P less than .05) when diets contained 3 ppm ergovaline than when diets contained 0 ppm ergovaline. An interaction (P less than .05) between dietary ergovaline concentration (0 vs 1.5 ppm) and environmental temperature (27 vs 34 degrees C) was found for OM intake and NDF and cellulose digestion. Ruminal fluid dilution and outflow rates decreased (P less than .01) even though water consumption increased (P less than .01) with increasing temperature. Rectal temperature increased (P less than .01) when ergovaline and ergotamine tartrate were fed and when sheep were exposed to increased environmental temperature. Under the dietary (and environmental) conditions described, our results suggest that alkaloid(s) present in infected tall fescue seed inhibit ruminal fiber digestion and increase the sensitivity of sheep to heat stress.

Acremonium↗

PubMed1990

Ruminal ciliated protozoa in cattle fed finishing diets with or without supplemental fat.

Ruminal samples were collected at slaughter from 364 unfasted steers fed different finishing diets to obtain information on numbers and species distribution of ciliated protozoa in feedlot cattle. Total numbers of protozoa averaged 1.59 X 10(5)/g of ruminal contents. A total of 47 steers (12.9%) were defaunated, but 4.1% of the steers possessed numbers of protozoa greater than 10(6)/g. Entodinium species did not always dominate the protozoan populations; 41 faunated steers (11.2%) were devoid of entodinia, and 79 additional steers (21.7%) possessed populations dominated (greater than 50%) by other genera. Isotricha was the most commonly occurring genus supplanting Entodinium, but Polyplastron and Epidinium were frequently present in high concentrations. Tallow and soybean soapstock supplementation reduced (P less than .05) numbers of protozoa in steers consuming wheat diets. However, yellow grease supplementation did not affect numbers of protozoa in steers fed either sorghum or corn diets. Average ruminal pH was 6.20 on the wheat diet, 6.05 on the corn diet, and 5.69 and 6.23 for the two sorghum diets, respectively. We found no correlation between ruminal pH and numbers of protozoa on any diet. The presence of relatively high protozoan concentrations and few defaunated animals in feedlot cattle necessitates reevaluation of the role that ciliated protozoa play in ruminal metabolism of animals fed processed, high-concentrate diets.

Animal Feed↗

PubMed1990

Effects of calcium soaps of long-chain fatty acids on feedlot performance, carcass characteristics and ruminal metabolism of steers.

Two trials were conducted to determine the effects of calcium soaps of long-chain fatty acids (calcium soap) on feedlot performance, diet digestibility, carcass characteristics and ruminal metabolism of steers fed diets (85% concentrate:15% corn silage) containing 0, 2, 4 or 6% calcium soap. In Trial 1, increasing calcium soap decreased (P less than .05) DM, CP and gross energy intake but increased total fatty acid intake. Feed to gain ratio tended to improve with increased calcium soap; gross energy conversion was not affected (P greater than .05) by diet. Average daily gain and hot carcass weight decreased (P less than .05) with addition of calcium soap; other carcass characteristics were not affected (P greater than .05). Apparent digestibilities of DM, N, energy and ash were not affected (P greater than .05) by calcium soap. Neutral detergent fiber digestibility increased linearly (P less than .08) with increasing calcium soap, whereas digestibility of total fatty acids was affected quadratically (P less than .05); fatty acid digestibility was similar among 0, 2 and 4% calcium soap diets but decreased for the 6% calcium soap diet. In Trial 2, increased calcium soap did not affect (P greater than .05) ruminal VFA concentrations, pH or in sacco NDF disappearance of orchardgrass following 12, 24 and 48 h of incubation. Calcium soap increased (P less than .07) ruminal concentrations of calcium soap fatty acids at 1, 2, 4 and 8 h postfeeding. Calcium soap did not improve performance of feedlot cattle fed high-concentrate diets. Further, calcium soap did not affect ruminal fermentation and did not dissociate significantly even when ruminal pH was below 6 for extended periods of time.

Animal Feed↗

PubMed1991

The influence of timing and the addition of urea to supplements containing DL-methionine on ruminal fermentation and cow weight change in beef cows.

A study was conducted to determine an optimal time for supplementation of DL-methionine in relation to time of forage intake by mature British breed-type crossbred cows, and two other experiments were conducted to determine whether ruminal ammonia concentration limited changes in disappearance rates in situ and ruminal functions caused by supplements containing DL-methionine. Experiments 1 and 2 used 4 x 4 Latin square designs with four cows in each experiment. Treatments in Exp. 1 were no supplement (CON), DL-methionine at feeding (0800), DL-methionine 4 h after feeding (1200), and DL-methionine 7 h after feeding (1500). Treatments in Exp. 2 were .5 kg of beet pulp (CON), .5 kg of beet pulp plus 16.5 g of DL-methionine (MET), .5 kg of beet pulp plus 16.5 g of DL-methionine and 55 g of urea (METU), and .4 kg of soybean (SOY). Experiment 3 was conducted in a 326-ha pasture with treatments of no supplement (CON), .5 kg of beet pulp plus 12.5 g of DL-methionine and 30 g of urea (METU), and .4 of kg soybean meal (SOY). In Exp. 1, in situ NDF disappearance rates of cows supplemented at 1200 and 1500 were greater (P less than .01) than those of cows supplemented at 0800. In Exp. 2, ruminal ammonia concentration was greatest (P less than .001) for METU (5.2 mg/dl) and least for CON (1.5 mg/dl). Disappearance rates in situ for DM differed (P less than .01) among treatments; METU was similar (P greater than .2) to SOY but faster (P less than .01) than MET. Disappearance rates of NDF were greatest (P less than .001) for METU-supplemented cows. In Exp. 3, DM and NDF disappearance rates were faster (P less than .10) for SOY than for METU. Cow BW change was positive for METU and SOY, and decrease in condition score was least (P less than .10) for METU- and SOY-treated cows. These studies indicate favorable ruminal responses to DL-methionine supplementation; however, the response depended on time of supplementation and ruminal ammonia concentration.

Ammonia↗

PubMed1991

Ruminal protein metabolism and intestinal amino acid utilization as affected by dietary protein and carbohydrate sources in sheep.

Eight wether lambs fitted with ruminal, duodenal, and ileal cannulas were used in a replicated 4 x 4 Latin square design to study the effects of carbohydrate and protein sources on ruminal protein metabolism and carbohydrate fermentation and intestinal amino acid (AA) absorption. Treatments were arranged as a 2 x 2 factorial. Carbohydrate sources were corn and barley; protein sources were soybean meal (SBM) and fish meal (FM). Diets contained 15.5% CP, of which 40% was supplied by SBM or FM. Corn or barley provided 39% of dietary DM that contained equal amounts of grass hay and wheat straw. Fish meal diets produced a lower (P less than .05) ruminal NH3 concentration and resulted in less CP degradation and bacterial protein flow to the duodenum than did SBM diets. Replacing SBM with FM increased (P less than .05) ruminal digestion of all fiber fractions. In addition, cellulose and hemicellulose digestibilities in the rumen tended to increase (P greater than .05) when barley replaced corn in the FM diets. Carbohydrate x protein interactions (P less than .05) were observed for OM digestion in the rumen and AA absorption in the small intestine (percentage of AA entering); these interactions were highest for the barley-FM diet. These results suggest that feeding FM with barley, which is high in both degradable carbohydrate and protein, might benefit ruminants more than feeding FM with corn, which is high in degradable carbohydrate but relatively low in degradable protein.

Amino Acids↗

PubMed1992

Ruminal biohydrogenation of linoleoyl methionine and calcium linoleate in sheep.

Four ruminally and duodenally cannulated Hampshire wethers were used in a 4 x 4 Latin square experiment to determine whether linoleoyl methionine and calcium linoleate would increase duodenal flow of unsaturated fatty acids (C18:2 + cis C18:1). All animals received the same basal diet plus a treatment enclosed in gelatin capsules that were placed directly in the rumen. Of the four experimental treatments, one was a control (empty capsules) and three were 5 g of fatty acid equivalent as either free linoleic acid, calcium linoleate, or linoleoyl methionine. Linoleoyl methionine had the lowest ruminal disappearance of C18:2 + cis C18:1. Ruminal loss of unsaturated fatty acids from each supplement exclusive of feed unsaturated fatty acids was 69.8, 92.9, and 94.6% for linoleoyl methionine, free linoleic acid, and calcium linoleate, respectively. Duodenal flow of methionine also was higher for linoleoyl methionine than for control, free linoleic acid, or calcium linoleate (2.5, 1.7, 2.0, and 2.5 g/d, respectively). Plasma linoleic acid was higher for linoleoyl methionine than for control or free linoleic acid but was not different from calcium linoleate (22.0, 17.8, 18.9, and 20.2% of total fatty acids, respectively). Plasma methionine levels were not different among treatments. Intestinal disappearance of unsaturated fatty acids did not differ among treatments. Linoleoyl methionine resisted ruminal biohydrogenation and was digested normally in the intestine. Calcium linoleate did not escape biohydrogenation by ruminal bacteria.

Absorption↗

PubMed1992

Alternate day supplementation of corn stalk diets with soybean meal or corn gluten meal fed to ruminants.

Four experiments were conducted to determine the effect of adding corn gluten mean (CGM) or soybean meal (SBM) at 24- or 48-h intervals to diets based on corn stalks. In each experiment corn stalks was the primary diet ingredient fed to wethers or steers. Monensin was also fed to determine whether its effects on ruminal fermentation would improve the efficiency of N utilization under these conditions. Evaluation criteria included ruminal fermentation characteristics, DM intake and utilization, N balance in sheep, and steer feedlot performance. Ruminal ammonia nitrogen (NH3 N) concentrations measured over time were higher (P < .05) when diets contained SBM. Diet did not influence (P > .10) total VFA concentrations in ruminal fluid. Differences in diurnal shifts in ruminal NH3 N and total VFA due to protein source resulted in diet x hour interactions (P < .05). Dry matter intake response to protein source and frequency of supplement feeding was variable. Dry matter digestibility and nitrogen digestibility were not affected (P > .10) by protein source or feeding interval. The 48-h interval feeding of CGM was favorable compared with 24-h interval feeding (P < .05). The opposite response occurred with SBM, resulting in a diet x feeding interval interaction (P < .05). Nitrogen retention was greater (P < .05) when CGM was fed and with alternate day feeding. Diets that contained CGM supported higher (P < .05) ADG and gain/feed than diets that contained SBM when fed to steer calves. Alternate day feeding of supplements that contained monensin was detrimental to steer performance under the conditions of these experiments. Corn gluten meal is an effective substitute for SBM when alternate day protein supplementation is practiced.

Ammonia↗

PubMed1992

Effects of supplemental protein percentage and feeding level on intake, ruminal fermentation, and digesta passage in beef steers fed prairie hay.

Twelve ruminally cannulated steers (average initial BW 357 kg) were allotted to four treatments (three steers per treatment) in a replicated 4 x 4 Latin square design with 21-d periods (12 d for adaptation and 9 d for collection) to compare the effects of protein supplements that differed in percentage of CP and feeding level on low-quality forage utilization. Treatments were 1) control (C), ad libitum access to 5.6% CP prairie hay, 2) C +600 g of DM.steer-1.d-1 of a 43% CP supplement based on cottonseed meal (PS), 3) C + 1,200 g of DM.steer-1.d-1 of a 22% CP supplement based on corn grain and cottonseed meal (GS), and 4) C + 600 g of DM.steer-1.d-1 of a 22% CP supplement based on corn grain and cottonseed meal (LS). Ruminal total VFA concentrations were increased 8% (P less than .07) by PS vs GS 1 h after supplementation. Among supplemented steers, ruminal acetate (mol/100 mol) was decreased 1.2 mol/100 (P less than .03) by GS vs PS and LS; however, supplementation did not affect (P greater than .10) acetate proportions compared with C. Neither propionate nor butyrate was affected (P greater than .10) by supplementation, but among supplemented steers, butyrate proportions were 8% greater (P less than .03) for GS than for PS and 5% less (P less than .10) for LS than for the average of GS and PS. Ruminal pH did not differ (P greater than .10) among treatments. Ruminal ammonia concentrations were increased 1.4 to 4.8 mg/100 mL (P less than .07) by supplementation and typically were less for LS than for PS and GS at most sampling times. Prairie hay DMI (average = 16.3 g/kg BW) was not affected (P greater than .10) by supplementation. Fluid dilution rate was 8% faster (P less than .01) when steers were supplemented than when they were not fed supplement, and fluid dilution rate was increased 4% (P less than .04) by GS compared with PS. Particulate digesta passage rate was not affected (P greater than .10) by treatment, but total tract retention time was decreased (P less than .01) 10% by supplementation. Extent and rate of prairie hay NDF digestion in situ were not greatly affected by supplementation, but in situ disappearance of supplement N was 6 to 10 percentage units less (P less than .06) for GS than for PS and 2 to 6 percentage units less for LS than for the average of PS and GS supplements.(ABSTRACT TRUNCATED AT 400 WORDS)

Ammonia↗

PubMed1992

Responses of serum folates of preruminant and ruminant calves to a dietary supplement of folic acid.

The effect of dietary supplemental folic acid on serum folates of preruminant and ruminant calves was studied. In Trial 1, doses of 0, .07, .14, .28, and .56 mg of folic acid per kilogram of BW were added to the milk of preruminant calves. In Trial 2, doses of 0, .5, 1, 2, and 4 mg of folic acid per kilogram of BW were incorporated into the concentrates of ruminant heifers. In the first part of each trial, serum folates were determined in blood samples taken 0, 1, 2, 4, 8, 16 (both trials), and 32 h (Trial 2) after a single meal supplemented with folic acid. In the second part of the two trials, the supplement of folic acid was given in feed during seven consecutive days. Blood samples were taken the day before the trial and subsequently every day during 7 d. In preruminant and ruminant calves, the area under the curve and the peak of concentration of serum folates after a meal increased with the dose ingested (P less than or equal to .05, linear and quadratic effect of doses, respectively) but the amount of folic acid needed to obtain a similar response was lower for preruminant than for ruminant calves. In preruminants, the time to reach the maximal concentration was 3 to 4 h after the meal, whatever the dose ingested (P less than or equal to .05), whereas in ruminants this time decreased with the dose ingested (quadratic effect of treatment, P less than or equal to .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1993

Effects of pregnancy on digesta kinetics and ruminal fermentation in beef cows.

Four pregnant and four nonpregnant, ruminally cannulated beef cows were used to evaluate the effects of the last trimester of pregnancy on digesta kinetics and ruminal fermentation. Before breeding, cows were allotted randomly either to pregnant (PR) or to nonpregnant (NP) groups; PR cows were bred at the first estrus after synchronization. All cows were fed long-stem fescue hay at 15 g of DM/kg of BW based on BW 120 d before parturition of pregnant cows (average BW of 642 kg). Collection periods, each lasting 9 d, began at 96, 68, 41, and 10 +/- 1.3 d before parturition. Particulate passage rate was greater (P < .05) and retention times and gastrointestinal fill were less (P < .05) for PR than for NP cows. Apparent total tract DM digestion, rate and extent (96-h in situ incubation) of NDF disappearance, and ruminal fluid kinetics were not affected (P > .10) by pregnancy. A physiological state x sampling day interaction was noted (P < .05) for ruminal NH3 N, total VFA concentrations, and molar proportions of butyrate. Ruminal pH and individual VFA proportions, however, did not differ (P > .10) between PR and NP cows, except for valerate, which was less (P < .05) for PR than NP cows. Results suggest that in late pregnancy with restricted feeding, passage rate of particulates increases without substantial changes in fermentation or extent of digestion.

Ammonia↗

PubMed1993

Effects of zinc-treated soybean meal on ruminal fermentation and intestinal amino acid flows in steers fed corn silage-based diets.

The objectives of this study were to examine the effects of feeding zinc-treated soybean meal (Zn-SBM) on ruminal fermentation patterns and duodenal AA flows in steers fed diets based on corn silage and corn. Six steers (385 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a replicated 3 x 3 Latin square design experiment with 14-d periods. Diets were supplemented with solvent-extracted soybean meal (SBM), Zn-SBM, or a 50:50 combination (CP basis) of SBM:Zn-SBM. Ruminal escape N content of SBM and Zn-SBM were 30.0 and 57.0%, respectively, based on 12-h Dacron bag incubation. Protein sources provided approximately 30% of total CP in diets containing 12.6% CP (DM basis). Dry matter intake was equalized throughout the study at 2.2% of average initial BW. Total N flow at the duodenum was similar (P = .47) among treatments, but a trend (P = .15) for increased nonmicrobial N flow occurred when SBM and Zn-SBM were fed in combination. Micobial N flow and true efficiency of microbial CP synthesis were not affected by treatment (P = .87 and .37, respectively). Ruminal fermentation characteristics generally were unaffected (P > .10) by protein source. A positive quadratic response (P < .06) was observed for total and essential AA flows to the small intestine because flows of total and essential AA from ruminally undegraded dietary protein tended (P = .12) to increase when SBM and Zn-SBM were fed in combination. Absorption of AA from the small intestine also showed a positive quadratic (P < .06) response for SBM:Zn-SBM. Microbial AA flow to the small intestine was similar (P = .87) among treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMed1993

Comparison of corn and barley with and without ruminal buffer in supplements fed in wheat straw-based diets to beef steers.

Ruminal fiber digestion is often decreased by supplementation of readily fermentable carbohydrates. Five ruminally cannulated beef steers were used in a 5 x 5 Latin square design to evaluate the effects of grain type (corn vs barley) and ruminal buffer (Na sesquicarbonate; 0 vs 1.2% of dietary DM) on ruminal digestion and fermentation in wheat straw-based diets. Grain supplements were 30% of the dietary DM. The 2 x 2 + 1 factorial arrangement of treatments included a control supplement that consisted primarily of soybean meal. Diets were fed once daily and were formulated to be 10% CP (DM basis). In situ DM (ISDMD) and NDF (ISNDFD) disappearance of wheat straw was measured at 0, 8, 16, 24, 32, 40, and 96 h incubation. To examine the effects of time after supplementation, 8-h incubations were performed at 0 to 8, 4 to 12, 8 to 16, 12 to 20, and 16 to 24 h after supplementation. Corn diets resulted in lower (P < .05) ISDMD for the 12- to 20- and 16- to 24-h periods than did barley diets. Averaged across 8-h intervals, the control treatment had greater ISDMD (P < .01) and ISNDFD (P < .05) than the grain treatments. Treatment differences were not observed for ISDMD and ISNDFD after 8 h of incubation. Ruminal fluid pH for barley diets was greater at 0, 16, and 20 h and less at 4 h after feeding than for corn diets (treatment x hour; P < .01). Propionate concentration was greater (P < .05) for corn than for barley diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗

PubMed1993

Tropical pasture hay utilization with slaframine and cottonseed meal: ruminal characteristics and digesta passage in wethers.

Sixteen mature, ruminally cannulated wethers (average BW = 41 +/- 1 kg) were fed a low-quality hay diet with or without a cottonseed meal (CSM) supplement and the parasympathomimetic agonist slaframine (SF). Treatments were basal diet (Mitchell grass hay, 4.8% CP, 46.8% ADF) available on an ad libitum basis, basal diet plus SF (8 micrograms/kg BW, 2 x daily i.m. injection), basal diet plus CSM (41.0% CP; 100 g/d), or basal diet plus SF and CSM. Treatments were arranged as a 2 x 2 factorial within a replicated 4 x 4 Latin square with 20-d periods followed by a 10-d adjustment during which only the basal diet was fed. All measurements were performed within the final 10 d of each period. Slaframine increased salivary flow by 10 to 35% (P < .07), ruminal fluid dilution rate by 8 to 11% (P < .10), and pH by 3 to 4% (P < .001). A twofold increase (P < .05) in ruminal cellulolytic bacteria numbers occurred in SF-treated wethers. Despite these SF-induced changes in the ruminal environment, whole-tract apparent nutrient digestibility, N and mineral balance, and ruminal VFA concentrations were not changed. Cottonseed meal increased forage intake by 34 to 54% (P < .001) and DM digestibility by 30% (P < .001). Cottonseed meal supplementation of a Mitchell grass hay diet improved nutritional status and attenuated live weight loss.

Alkaloids↗

PubMed1994

The influence of intake level and corn processing on digestibility and ruminal metabolism in steers fed all-concentrate diets.

The effects of intake (ad libitum and 70% of ad libitum) and corn processing (whole or rolled) on digestion, ruminal metabolism, and blood metabolites were determined in a 2 x 2 factorial experiment using eight ruminally fistulated steers. All-concentrate diets were fed with adjustments to dietary concentrations of N, vitamins, and minerals to ensure equal daily intake of these nutrients. Digestion of DM, OM, and starch were affected by an intake x processing interaction (P < .03). Starch digestion for the low-intake, whole-corn diet was much lower than that for the other three diets. This decrease in starch digestion was the major reason for the interaction. Nitrogen digestion was improved (P < .03) with limited intake but was not affected by processing. Ruminal volume and ruminal turnover (percentage/hour) were both reduced (P < .03) on the low-intake diet. Molar proportion of acetate was reduced and propionate was increased (P < .01) for steers receiving high intake of rolled corn compared with the other three diets. Butyrate concentrations were increased (P < .01) when corn was rolled before feeding. Ruminal pH was higher immediately before feeding for steers receiving whole corn than for those receiving rolled corn. Decreases in pH were observed for rolled corn 2 to 9 h after feeding, suggesting a faster rate of fermentation of rolled corn than of whole corn. Concentrations of blood glucose and insulin were not affected by intake or processing. It was concluded that processing corn can improve DM and OM digestibility if intake is restricted and that N digestion is improved with restricted feeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗

PubMed1995

Influence of moisture content of forage on ruminal functional specific gravity and passage of digesta.

Four crossbred beef steers (392 kg BW) fitted with ruminal cannulas were used in a 4 x 4 Latin square experiment with treatments arranged in a 2 x 2 factorial to evaluate effects of forage species (F) and reconstitution (R) on apparent digestibility, ruminal kinetics, and digesta functional specific gravity (FSG). Dietary treatments were alfalfa (Medicago sativa L.) and timothy (Phleum pratense L.) hays (90% DM) and the same hays reconstituted with water to 38% DM. Apparent DM digestibility was unaffected by R or F. Proportion of ruminal digesta with a FSG of .9 to 1.1 or 1.1 to 1.2 decreased linearly (P < .05) after feeding, whereas the proportion with FSG > 1.2 increased linearly (P < .01). Reconstitution decreased (P < .10) the proportion of ruminal digesta with FSG of 1.1 to 1.2 and increased (P < .10) the proportion with a FSG > 1.2 compared with the hay diets. Reconstitution decreased digesta passage rate for timothy forage; no influence on passage rate for alfalfa was detected (F x R, P < .10). Ruminal DM pool was increased by reconstitution (P < .10). Inert particles of 1-mm length passed from the rumen at a faster rate (P < .05) than 3-mm particles. Inert particles with SG of 1.32 passed from the rumen at a faster rate (P < .05) in the reconstituted alfalfa than in the dry alfalfa diet but at a slower rate in the reconstituted timothy than in the dry timothy diet. These results suggest that factors other than SG of the digesta can have a profound effect on passage of forage particles from the rumen.

Animal Feed↗

PubMed1995

Absorption of L-carnosine, L-methionine, and L-methionylglycine by isolated sheep ruminal and omasal epithelial tissue.

The absorption of carnosine, methionine, and methionylglycine (using 35S-methionine and 35S-methionylglycine as representative markers) across ruminal and omasal epithelia collected from four (carnosine) and seven sheep (methionine and methionylglycine) were studied using parabiotic chambers that were repeatedly sampled over a 240-min incubation. The quantity of all substrates transferred was linearly (P < .01) dependent on initial substrate concentration and time. More (P < .01) carnosine, methionine, and methionylglycine was transferred across omasal than across ruminal epithelia. Carnosine was absorbed across both tissues without hydrolysis. Methionylglycine was transferred intact across both tissues. A greater (P < .01) quantity was hydrolyzed by omasal than by ruminal epithelia, after 240 min of incubation. Greater (P < .06) quantities of methionine and methionylglycine accumulated in ruminal tissue after 240 min. Total absorption of methionine and methionylglycine did not differ within tissues, but total absorption of both substrates was greater (P < .01) by omasal tissues. There was little evidence for saturable absorption. These results indicate that omasal epithelial tissue possesses a greater ability to absorb both free and peptide-bound amino acids than does ruminal epithelial tissues.

Animals↗