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PubMed1993

Nycterohemeral eating and ruminating patterns in heifers fed grass or corn silage: analysis by finite Fourier transform.

Average daily and within-day nycterohemeral patterns of eating and ruminating behavior were determined in six Holstein-Friesian heifers (average BW = 427 kg) given ad libitum access to either corn or grass silage in a two-period crossover design. Rhythm components (number of cycles/24 h) were characterized by finite Fourier transform of the 24-h mastication activities as measured during 4 d by continuous jaw movement recordings. Average daily voluntary intake of corn silage was 8.2% greater (P = .05) than that for grass silage and was associated (P < .05) with fewer meals and shorter daily, unitary eating and ruminating times, and smaller number of rumination boli. Analysis of variance of the daily mean of hourly activities and Rhythm Components 1 to 12 indicated effects of (P < .05) silage type (S), animal (A), period (P), and a significant interaction (S x A x P) for each mastication activity. The finite Fourier transform was reparameterized to express the amplitude (as periodograms) and phase of each rhythm component. Rhythm Components 1, 3, and 4 contributed primarily to explaining the total dispersion of the 24-h series of time spent eating and ruminating, for both silage types and individual heifers. Relative importance of Rhythm Component 1 of time spent eating, indicative of a main circadian pattern, was related positively to pedigree value for milk production (P = .01) and negatively to milk protein concentration (P = .09).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

Ruminal characteristics, microbial populations, and digestive capabilities of newly weaned, stressed calves.

Eight ruminally fistulated steers, 7 to 8 mo old, were used in a completely randomized, 2 x 2 factorial experiment to determine the effects of energy density and protein source in receiving diets on in situ DM, NDF, and N disappearance, concentrations of ruminal bacteria, protozoa, ammonia, and pH. Two energy densities (1.80 and 1.48 Mcal/kg of NEm) and two protein sources (spray-dried blood meal [SDBM] and soybean meal [SBM]) were compared. Fistulated steers were weaned, transported by truck, and held in a sale barn before their arrival at the feedlot. On d 0 (day of arrival at the feedlot), DMI was 62% of DMI on d 7 after arrival. Overall, feeding a high-energy diet resulted in lower (P < .01) in situ DM disappearance (DMD) of orchardgrass than feeding a low-energy diet at both 24 and 48 h. In situ 24-h DMD averaged 46.6% on d-3 and 41.6% on d 0, whereas 48-h in situ DMD on d -3 and 0 averaged 58.2 and 58.6%, respectively, indicating the ruminal microbial population was not inhibited in its ability to digest available substrate. Additionally, there were no differences (P > .10) in 48-h in situ NDF disappearance between d -3 and 0 (58.8 vs 57.8%), respectively. No differences (P > .10) occurred in the concentration of total bacteria, or cellulolytic bacteria, due to feed and water deprivation. Concentration of total protozoa was lower (P < .05) on d 0 than at any other time. Entodinium averaged 72.5% of genera before weaning, and more than 90% of genera found on all treatments by d 21. Diplodinium and Epidinium percentages tended to decline after weaning. Isotricha concentrations were low and Dasytricha were eliminated after d 7. In conclusion, the concentration of ruminal bacteria and the ability to digest available substrate were not decreased immediately after weaning, trucking, and 24 h of feed and water deprivation.

Ammonia↗
PubMed1994

In vitro determination of ruminal protein degradability using [15N]ammonia to correct for microbial nitrogen uptake.

An in vitro procedure was developed to estimate rate and extent of ruminal protein degradation using [15N]H3 to quantify uptake of protein degradation products for microbial protein synthesis. Incubations were conducted for 6 h in stirrer flasks with ruminal inoculum plus buffer, reducing solution, pectin, soluble carbohydrates, and added (15NH4)2SO4. Seven protein concentrates were tested in the system. Samples of media were analyzed for 15N enrichment of NH3, microbial N, and total solids N. Degradation rate was computed from net (i.e., protein-added minus blank) release of NH3 N plus net synthesis of microbial protein N; escape was estimated assuming ruminal passage rate = .06/h. Over the course of the incubations, pH was stable at 6.6, protozoal numbers increased slightly, and microbial protein content increased by more than 200%. Free AA had not accumulated at the end of the incubations. Microbial protein synthesis was a linear function (P < .001; r2 = .780) of extent of degradation. Mean degradation rates and ruminal escapes determined were, respectively, .569/h and 10% (casein), .148/h and 29% (solvent soybean meal), .036/h and 63% (expeller soybean meal), .026/h and 70% (low solubles fish meal), .063/h and 49% (high solubles fish meal), .034/h and 64% (corn gluten meal), and .050/h and 55% (roasted soybeans). Overall, degradation rates averaged 28% greater than those previously estimated using an inhibitor in vitro system; however, rates obtained for the fish meals using the 15N method were slower.

Ammonia↗
PubMed1994

Ruminal digestion and glycosyl linkage patterns of cell wall components from leaf and stem fractions of alfalfa, orchardgrass, and wheat straw.

Samples of alfalfa, orchardgrass, and wheat straw were hand-separated into leaf and stem fractions that were subjected to in situ ruminal fermentation for various lengths of time to assess the rate and extent of degradation of cell wall neutral monosaccharides, uronic acids, acetyl groups, and hydroxycinnamic acids. A second objective was to measure the glycosyl linkage patterns of leaf and stem fractions of substrates before and after ruminal fermentation. Samples were fermented for 0, 6, 12, 24, 48, 96, and 192 h in each of two ruminally cannulated steers. In situ disappearance data were fitted to a first-order exponential equation to estimate the following substrate parameters: insoluble, potentially digestible fraction (fd), indigestible fraction (fi), and fractional rate constant of degradation of the potentially digestible fraction (k). Leaves contained larger concentrations of crude protein and smaller concentrations of cell wall components than did stem fractions. Estimates of fi were 7.3, 39.2, 22.1, 49.3, 27.7, and 36.3 for dry matter disappearances for alfalfa leaf, alfalfa stem, orchardgrass leaf, orchardgrass stem, wheat straw leaf, and wheat straw stem, respectively. Averaged across substrates, estimates of fi for arabinose, galactose, glucose, xylose, uronic acids, acetyl groups, and p-coumaric acid were 16.5, 11.4, 14.8, 31.2, 12.8, 25.3, and 22.6% in leaf fractions and 29.5, 19.9, 37.5, 56.2, 35.0, 52.4, and 44.6% in stem fractions. Rates of digestion of all monomeric components except galactose and xylose were greater (P < .05) for alfalfa than for orchardgrass or wheat straw. Differences in digestibility of cell wall components from leaf and stem fractions were greater in alfalfa and orchardgrass than in wheat straw. Glycosyl linkage analysis indicated that xylans in leaf and stem fractions of alfalfa, orchardgrass leaf, and wheat straw stem that resisted degradation had a lower degree of substitution with acid-labile constituents (i.e., other monosaccharides) than was found in original substrates. Different rates and extents of digestion of leaf and stem fractions of forages explain part, but not all, of the observed differences in digestibilities of cell wall monomers by ruminants.

Animals↗
PubMed1995

Butylsoyamide protects soybean oil from ruminal biohydrogenation: effects of butylsoyamide on plasma fatty acids and nutrient digestion in sheep.

Based on previous results showing partial resistance of fatty acyl amides to ruminal biohydrogenation, butylsoyamide was added to sheep diets in an attempt to increase unsaturation of plasma fatty acids. Twelve wethers averaging 34 +/- 3.2 kg BW were randomly assigned to three diets containing either no added fat (control), 5% soybean oil, or 5% butylsoyamide. Dry matter intake was greater (P < .05) for sheep fed butylsoyamide than for sheep fed soybean oil (740 and 581 g/d, respectively), but neither fat supplement differed from the control diet (680 g/d). The soybean oil supplement reduced (P < .05) total VFA concentration (59.0 and 38.7 mM) and acetate:propionate (4.10 and 2.56) in ruminal samples compared with the control diet. Butylsoyamide had no effect (P > .05) on total VFA (54.4 mM) or acetate:propionate (2.96). Total tract ADF digestibility was not affected (P > .05) by either fat supplement. Relative to the control diet, soybean oil increased (P < .05) plasma linoleic acid concentration 22% compared with a 58% increase from feeding butylsoyamide (26.7, 32.6, and 42.1% of total fatty acids, respectively). Linoleic acid concentration in plasma neutral lipids, relative to the control diet, increased 15.8% (P < .05) for soybean oil compared with 64.9% (P < .05) for butylsoyamide (31.6, 36.6, and 52.1% of total fatty acids, respectively). Converting soybean oil triglycerides to fatty acyl amides substantially reduces negative effects of the oil on ruminal fermentation and increases unsaturated fatty acids in plasma. The increase in plasma unsaturated fatty acids demonstrates at least partial resistance of fatty acyl amides to ruminal biohydrogenation and their digestion and absorption postruminally.

Animal Feed↗
PubMed1995

Interaction of feed intake level on comparative ruminal and total tract digestion of dry-rolled and steam-flaked corn.

Four Holstein steers (208 kg) with "T" cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square design experiment to evaluate the interaction of feed intake level on comparative ruminal and total tract digestion of dry-rolled and steam-flaked corn. The basal diet contained (DM basis) 6% alfalfa hay, 6% sudangrass hay, 75% corn, 2% yellow grease, 5% cottonseed meal, 3% cane molasses, and 3% supplement. The corn portion of the diet was provided as either dry-rolled (density = .54 kg/L) or steam-flaked (density = .36 kg/L). Dry matter intake was restricted to allow for .64 vs 1.28 kg/d of weight gain (1.6 vs 2.4% of BW). Ruminal digestibility of OM, starch, and feed N were not affected (P > .10) by DMI. Postruminal digestion of OM and N and total tract digestibility of OM and DE decreased (P < .05) as DMI was increased. Total tract starch digestibility was not influenced (P > .10) by DMI. Steam flaking corn increased (P < .05) ruminal digestibility of OM and starch and postruminal and total tract digestibility of OM, starch, N, DE, and ME. Increasing DMI and steam flaking decreased (P < .05) ruminal pH and molar proportion of acetate. It is concluded that corn processing is the primary factor influencing site and extent of starch digestion. Decreasing DMI increases DE value of the diet; however, ME value is not affected because of increased energy loss as methane.

Animal Feed↗
PubMed1995

Different strains of Saccharomyces cerevisiae differ in their effects on ruminal bacterial numbers in vitro and in sheep.

A ruminal simulation device (Rusitec) was used to compare the effects of Saccharomyces cerevisiae strains NCYC 240, NCYC 694, NCYC 1026, NCYC 1088, and Yea-Sacc (a commercial product containing S. cerevisiae) on ruminal fermentation. S. cerevisiae NCYC 240, NCYC 1088, NCYC 1026, and NCYC 694 were grown on malt extract at 30 degrees C in aerated fed-batch culture and harvested along with spent growth medium by freeze-drying. Each vessel received daily 20 g of a basal diet consisting of hay, barley, molasses, fishmeal, and a minerals/vitamins mixture at 500, 299.5, 100, 91, and 9.5 g/kg of DM, respectively. Yeast preparations (500 mg/d) were added along with the feed. S. cerevisiae NCYC 240, NCYC 1026, and Yea-Sacc stimulated total and cellulolytic bacterial numbers, whereas S. cerevisiae NCYC 694 and NCYC 1088 had no effect on the numbers of bacteria. The effects of S. cerevisiae NCYC 240, NCYC 1026, and Yea-Sacc on ruminal fermentation were further investigated in vivo using ruminally cannulated sheep fed 1.5 kg/d of the diet used in Rusitec, supplemented with 2 g/d of yeast culture. All treatments tended to stimulate total and cellulolytic bacterial numbers. However, the stimulation was only statistically significant for S. cerevisiae NCYC 1026 with total bacterial numbers and S. cerevisiae NCYC 240 with cellulolytic bacteria (P < .05). Increased bacterial numbers were associated with an increase in the rate of straw degradation in the rumen and a nonsignificant (P > .05) increase in the excretion of purine derivatives in the urine, measured as an index of microbial nitrogen leaving the rumen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Adaptation to small intestinal starch assimilation and glucose transport in ruminants.

Four crossbred steers (380 +/- 6 kg) and seven Polypay wethers (40.3 +/- 6 kg) fitted with hepatic venous, hepatic portal, mesenteric venous and arterial, ruminal, and abomasal (steers) or duodenal (wethers) catheters were used in two crossover design experiments to evaluate adaptation to small intestinal starch and glucose transport. Steers were fed 8.6 kg/d and sheep were fed .9 kg/d of alfalfa hay in 12 equal portions and infused with an alpha-amylase partial starch hydrolysate (SH) either postruminally (adapted) or ruminally (unadapted) for 4 (steers; 40 g/h) or 5 (sheep; 6 g/h) days before measuring splanchnic flux of metabolites. On the day of flux measurements, ruminal SH infusion was switched to the postruminal site in unadapted animals. Flux measurements were made 3 to 6 h after switching infusion site for steers and 2 to 5 h for sheep. Phlorizin, a competitive inhibitor of Na/glucose cotransport, was then postruminally infused (550 and 500 mumol/h for steers and sheep, respectively) and flux measurements repeated from h 9 to 12 (steers) and h 7 to 10 (sheep). In the steers, adaptation increased (P < or = .09) portal-drained visceral (PDV) glucose release 26 mmol/h and decreased hepatic uptake of lactate 20 mmol/h. Abomasal infusion of phlorizin decreased (P = .01) net PDV glucose flux 40 mmol/h and concomitantly increased (P = .05) hepatic release of glucose by 47 mmol/h. In sheep, duodenal infusion of phlorizin increased (P < or = .005) portal and hepatic blood flow and decreased (P < or = .02) PDV release of glucose and lactate by 9 and .4 mmol/h, respectively. The liver released 4.2 mmol/h more (P = .09) glucose and removed 3.2 mmol/h more lactate (P = .09) glucose and removed 3.2 mmol/h more lactate (P = .001); arterial glucose decreased (P = .003) .75 mM in response to phlorizin. Phlorizin also caused loss of glucose in the urine of sheep (.09 mmol/h). Adaptation did not alter net splanchnic flux of glucose, lactate, oxygen, or alpha-amino N. These studies indicate that ruminants maintain the Na/glucose cotransporter when consuming little preformed alpha-glucosidic polymers and that the liver increases glucose release to compensate for reduced PDV delivery of glucose to maintain glucose homeostasis. In addition, the steers maintain at least 960 mmol/d and the sheep maintain at least 216 mmol/d of glucose transport capability regardless of adaptation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1996

Use of sodium dodecyl sulfate polyacrylamide gel electrophoresis to measure degradation of soluble soybean proteins by Prevotella ruminicola GA33 or mixed ruminal microbes in vitro.

Degradation of soluble soybean meal proteins by Prevotella ruminicola GA33 and mixed ruminal bacteria was studied using SDS-PAGE. This technique facilitated the quantification of peptides (molecular weight > or = kDa) released during the partial hydrolysis of soybean proteins. In P. ruminicola incubations, conglycinin alpha and alpha' subunits were degraded completely within 4 h, whereas the beta subunit of beta-conglycinin as well as the basic and acidic polypeptide components of glycinin were more resistant to degradation. Several peptides derived from digested soybean proteins appeared during the incubation. The N-terminal amino acid sequences of these peptides were similar to amino acid sequences in soybean proteins. The N-terminus of a 23-kDa peptide was identical to the N-terminus of the beta subunit of beta-conglycinin; the N-terminus of a 59-kDa peptide differed from amino acids 101 to 115 of the alpha subunit of beta-conglycinin by two of 15 amino acids; the N-terminus of a 64-kDa peptide differed from amino acids 67 to 76 of the alpha' subunit of beta-conglycinin by three of 10 amino acids. The transient accumulation of these peptides when soluble soybean proteins were incubated with mixed ruminal microorganisms suggests a role for P. ruminicola in the early stages of protein digestion in the rumen. Approximately 30% of the soluble soybean protein incubated with mixed ruminal microorganisms was not degraded after 9 h, and SDS-PAGE indicated that the basic subunit of glycinin and several peptides (molecular weights less than 23 kDa) make an appreciable contribution to metabolizable protein when soybean protein is fed to ruminants.

Amino Acid Sequence↗
PubMed1996

Barley varieties for finishing steers: II. Ruminal characteristics and rate, site, and extent of digestion.

Four ruminally and abomasally cannulated steers were used to evaluate the effects of barely variety on rate, site, and extent of digestion of high-concentrate diets. The treatments compared were 1) corn, 2) Gunhilde barley (GUN), Harrington barley (HAR), and 4) Medallion barley (MED). Diets were balanced to be isocaloric and isonitrogenous. Ruminal OM digestion was greater (P = .04) in steers fed corn than in those fed GUN, HAR, and MED (61.9 vs average 53.7%). No differences (P > .10) were seen in ruminal starch digestion (average 92.8%) or in starch flow to the abomasum (average 199 g/d) between diets. Total tract digestion of starch was greater (P = .09) in steers fed barley than in those fed corn (average 98.6 vs 95.7%). Total and nonammonia N presented to the abomasum were greater (P < .05) for steers fed HAR and GUN than for those fed MED and corn. Microbial N flow was lowest (P = .01) in corn-fed steers, highest in steers fed GUN and HAR, and intermediate in steers fed MED. Microbial efficiency was 59% greater (P = .03) in steers fed barley than in steers consuming corn. Ruminal acetate: propionate was lower (P = .002) in steers fed corn and HAR than in those fed GUN and MED. Compared to GUN, HAR, and MED barleys, corn had a lower (P < .03) rate (-.11 vs average -.47) and extent (15 h; 70.3 vs average 98.1%) of in situ starch disappearance. Differences in digestive characteristics found between barley varieties may contribute to differences in animal performance.

Acetates↗
PubMed1997

Free amino acid supplementation to steers: effects on ruminal fermentation and performance.

Three studies were conducted to evaluate amino acid utilization by cattle. In Exp. 1, five steers (580 kg) were fed 86% rolled corn diets with mixtures of amino acids containing up to 6 g/d DL-Met, 24 g/d L-Lys, 6 g/d L-Thr, and 3 g/d L-Trp. Treatments had little effect on ruminal fermentation, diet digestibility, N flow to the duodenum, or microbial efficiency. Ruminal concentrations of Met and Lys increased linearly (P < .05) with amino acid supplementation, whereas Thr responded quadratically, and Trp was not altered. In Exp. 2, four steers (414 kg) were used to measure effects of dietary monensin or laidlomycin propionate in high-grain diets supplemented with amino acids. Ionophores had no significant effect on ruminal fermentation or outflows of amino acids from the rumen. In Exp. 3, 100 steers (287 kg initial BW) were fed diets containing 1% of a nonprotein N source. Treatments were 1) no supplemental N (UREA), 2) UREA plus soybean meal (SBM), 3) UREA plus 2 g/d DL-Met, 8 g/d L-Lys, 2 g/d L-Thr, and 1 g/d L-Trp, or 4) UREA plus 4 g/d DL-Met, 16 g/d L-Lys, 4 g/d L-Thr, and 2 g/d L-Trp. During the growing period (diets based on whole-plant milo silage), gains were higher for SBM-supplemented steers than for UREA steers and intermediate for steers supplemented with amino acids. Few significant differences in performance were observed among treatments during the finishing phase (diets based on dry-rolled corn) or for the entire experiment, but cattle fed SBM or amino acids tended to be fatter and have better marbling scores and quality grades. Amino acids did not greatly alter ruminal fermentation or cattle performance.

Amino Acids↗
PubMed1997

Effect of ruminally degraded protein on protein available at the intestine assessed using blood amino acid concentrations.

The effect of increasing amounts of ruminally degraded protein on protein available at the intestine was studied using the concentration of blood plasma branched-chain amino acids as an indicator of protein flow to the small intestine. Five ruminally cannulated cows in midlactation were used in a 5 X 5 Latin square design experiment and were fed a diet containing 20% alfalfa silage, 40% corn silage, 30% shelled, coarsely ground corn, and 8% soybean meal (DM basis). Each experimental period was 17 d. Each period contained subperiods: 1 (5 d), 2 (5 d), and 3 (7 d). In addition to the basal diet, cows were given casein infusions of 0, .5, 1.0, and 2.0 kg/d. During subperiod 1, the full amount of casein was infused into the abomasum (A100); in subperiod 2, 10% of each casein level was infused into the abomasum (A10); and, during subperiod 3, the full amount of casein was infused into the rumen (R100). The concentration of branched-chain amino acids (Ile, Leu, and Val) in blood plasma increased as amounts of casein infused into the abomasum increased to the full amount. There was no increase in branch-chain amino acids when the same amount of casein was infused into the rumen, suggesting that ruminally degraded protein was adequate in the basal diet and the increased supply of degraded protein from ruminally infused casein did not increase the flow of protein to the small intestine.

Amino Acids, Branched-Chain↗
PubMed1998

The role of pH in regulating ruminal methane and ammonia production.

When steers (n = 4) were fed increasing amounts of concentrate (0, 45, or 90% of DM) and decreasing amounts of forage, the VFA concentration increased (P < .001) and ruminal pH, acetate:propionate ratio, and dissociated ammonia declined (P < .001). Acetate:propionate ratio and dissociated ammonia were highly correlated (r2 = .82 and .65, respectively) with ruminal pH. In vivo acetate:propionate ratio was highly correlated (r2 = .78) with the capacity of the bacteria to produce methane from H2 and CO2 in vitro, and in vivo pH-dissociated ammonia was correlated (r2 = .59) with the capacity of the bacteria to produce ammonia from protein hydrolysate. The role of pH in regulating methane and ammonia production was supported by the effect of pH in vitro. When bacteria from cattle fed concentrate or forage were incubated at pH values from 6.5 to 5.7, methane production decreased (P < .001) from 48 to 7 nmol x mg protein(-1) x min(-1) and from 14 to 2 nmol x mg protein(-1) x min(-1), respectively. The reduction in in vitro pH (6.5 to 5.7) also decreased (P < .001) the rates of ammonia production, but only if the bacteria were obtained from cattle fed forage (28 to 15 nmol x mg protein(-1) x min(-1)). Bacteria from cattle fed 90% concentrate had similar (P > .05) rates of ammonia production at pH 6.5 to 5.7 (approximately 12 nmol x mg protein(-1) x min(-1)). These results indicated that ruminal pH affected ruminal methane production, acetate:propionate ratio, deamination, and ammonia concentration.

Acetates↗
PubMed1999

Technical note: a device for obtaining time-integrated samples of ruminal fluid.

A device was adapted to allow for time-integrated sampling of fluid from the rumen via a cannula. The sampler consisted of a cup-shaped ceramic filter positioned in the ventral rumen of a cannulated cow and attached to a tube through which fluid entering the filter was removed continuously using a peristaltic pump. Rate of ruminal fluid removal using the device was monitored over two 36-h periods (at 6-h intervals) and was not affected (P > .05) by time, indicating that the system was not susceptible to clogging during this period. Two cows having ad libitum access to a totally mixed ration were used in a split-block design to evaluate the utility of the system for obtaining time-integrated samples of ruminal fluid. Ruminal fluid VFA concentration and pattern in samples collected in two replicated 8-h periods by the time-integrated sampler (at 1-h intervals) were compared with composite samples collected using a conventional suction-strainer device (at 30-min intervals). Each 8-h collection period started 2 h before or 6 h after feeding. Results indicated that total VFA concentration was not affected (P > .05) by the sampling method. Volatile fatty acid patterns were likewise unaffected (P > .05) except that acetate was 2.5% higher (P < .05) in samples collected 2 h before feeding and valerate was 5% higher (P < .05) in samples collected 6 h after feeding by the suction-strainer device. Although significant, these differences were not considered physiologically important. We concluded that use of the ceramic filter improved the sampling of ruminal fluid by simplifying the technique and allowing time-integrated samples to be obtained.

Animals↗
PubMed2000

Dietary copper effects on lipid metabolism, performance, and ruminal fermentation in finishing steers.

Sixty Angus steers (391.1+/-6.1 kg) were used to determine the effects of dietary Cu concentration on lipid metabolism and ruminal fermentation. Steers were stratified by weight and randomly assigned to treatments. Treatments consisted of 0 (control), 10, or 20 mg of supplemental Cu (as CuSO4)/kg diet DM. Steers were housed in pens equipped with individual electronic Calan gate feeders. On d 86 and 92, ruminal fluid was collected from two steers/treatment for IVDMD determination. Equal numbers of steers per treatment were slaughtered after receiving the finishing diets for 96 or 112 d. Gain, feed intake, feed efficiency, IVDMD, and ruminal VFA molar proportions were not affected by Cu supplementation. Copper supplementation increased (P < .05) liver Cu concentrations, and steers supplemented with 20 mg Cu/kg DM had higher (P < .05) liver Cu concentrations than steers supplemented with 10 mg Cu/kg DM. Serum total cholesterol concentrations were reduced by d 56 and at subsequent sampling dates in steers receiving supplemental Cu. Longissimus muscle cholesterol concentrations were lower (P < .10) in steers supplemented with Cu. Backfat depth was less (P < .05) in steers receiving supplemental Cu, but marbling scores were similar across treatments. Unsaturated fatty acid composition of longissimus muscle was increased (P < .05) and saturated fatty acid composition tended (P < .12) to be reduced in Cu-supplemented steers. Polyunsaturated fatty acid concentrations were higher (P < .05) in steers receiving Cu. These results indicate that addition of 10 or 20 mg Cu/kg to a high-concentrate diet containing 4.9 mg Cu/kg DM alters lipid and cholesterol metabolism in steers but does not affect ruminal fermentation.

Animals↗
PubMed2001

Effect of forage:concentrate ratio on ruminal digestion and duodenal flow of fatty acids in ewes.

The objective of this study was to determine the forage:concentrate ratio that would provide the greatest duodenal flow of unsaturated fatty acids in ewes supplemented with soybean oil and to determine how diets differing in forage content affect flow of conjugated linoleic acid (CLA) and trans-vaccenic acid (18:1(trans-11)). Five mature ewes (66.5 +/- 12.8 kg) fitted with ruminal and duodenal cannulas were used in a 5 x 5 Latin square experiment. Diets were isonitrogenous and included bromegrass hay, cracked corn, corn gluten meal, urea, and limestone. Dietary fat was adjusted to 6% with soybean oil. Five ratios of forage:concentrate (18.4:81.6, 32.2:67.8, 45.8:54.2, 59.4:40.6, and 72.9:27.1) were fed at 1.3% of BW daily in equal allotments at 0630 and 1830. After 14 d, Cr2O3 (2.5 g) was dosed at each feeding for 7 d and ruminal, duodenal, and fecal collections were taken for the next 3 d. Duodenal flow of 18:0 increased linearly (P < 0.01) with dietary forage. Duodenal flow of 18:1(cis-9) and 18:2(cis-9,12) decreased (P < 0.001) but duodenal flow of 18:3(cis-9,12,15) increased (P < 0.01) with increased dietary forage. Biohydrogenation of dietary unsaturated fatty acids increased (P < 0.001) as dietary forage increased, which was concomitant with increased ruminal pH. Duodenal flow of 18:2(cis-9,trans-11) increased linearly (P < 0.01) with increased dietary forage but increased abruptly when forage was fed at 45.8%. Duodenal flow of the trans-10, cis-12 and cis-10, cis-12 CLA isomers decreased as dietary forage increased, but flow tended to increase on the highest-forage diet, resulting in both linear (P < 0.01) and quadratic (P < 0.01) effects. Duodenal flow of 18:1(trans-11) decreased from 8.28 g/d on the 18.4% forage diet to 5.47 g/d on the 59.4% forage diet then increased to 7.29 g/d on the highest-forage diet (quadratic, P < 0.1). Duodenal flow of 18:1(trans-11) was 27- to 69-fold greater than flow of CLA. We conclude that when ewes were fed a 6% crude fat diet duodenal flows of dietary fatty acids changed incrementally as dietary forage was increased, whereas changes in flows of CLA isomers seemed to be more abrupt. Biohydrogenation changes were gradual with diet, suggesting a gradual shift in ruminal microbial populations with increasing forage. Finally, the highest-concentrate diet supported the greatest duodenal flows of dietary unsaturated fatty acids, as well as the highest flow of 18:1(trans-11).

Animal Feed↗
PubMed2002

Effect of high-oil corn or added corn oil on ruminal biohydrogenation of fatty acids and conjugated linoleic acid formation in beef steers fed finishing diets.

Three Angus steers (410 kg) cannulated in the proximal duodenum were used in a replicated 3 x 3 Latin square to evaluate the effects of dietary lipid level and oil source on ruminal biohydrogenation and conjugated linoleic acid (CLA) outflow. Dietary treatments included: 1) typical corn (TC; 79.2% typical corn), 2) high-oil corn (HOC; 79.2% high-oil corn), and 3) the TC diet with corn oil added to supply an amount of lipid equal to the HOC diet (OIL; 76.9% TC + 2.4% corn oil). Duodenal samples were collected for 4 d following 10-d diet adaptation periods. Data were analyzed with animal, square, period, and treatment in the model and planned, nonorthogonal contrasts were used to test the effects of dietary lipid content (TC vs HOC and OIL) and oil source (HOC vs OIL) on ruminal biohydrogenation. Intake and duodenal flow of total long-chain fatty acids were increased (P < 0.05) by over 63% for diets containing more lipid regardless of oil source. Apparent ruminal dry matter and long chain fatty acid digestibilities were not altered (P > 0.05) by dietary lipid level or oil source. Ruminal biohydrogenation of total and individual 18-carbon unsaturated fatty acids was greater (P < 0.05) for diets with higher lipid content. Biohydrogenation of oleic acid was greater (P < 0.05) for HOC than OIL, but biohydrogenation of linoleic acid was lower (P < 0.05) for HOC than OIL. Duodenal flows of palmitic, stearic, oleic, linoleic, and arachidic acids were more than 30% greater (P < 0.05) for diets containing more lipid. Flow of all trans-octadecenoic acids was greater (P < 0.05) for diets containing more lipid. Corn oil addition increased (P < 0.05) the flow of trans-10 octadecenoic acid and the trans-10, cis-12 isomer of CLA by threefold compared to feeding high-oil corn. Feeding high-oil corn or adding corn oil to typical corn rations increased intake, biohydrogenation, and duodenal flow of unsaturated long-chain fatty acids. Compared with high-oil corn diets, addition of corn oil increased duodenal flow of trans-10, trans-12 and cis-12 isomers of octadecenoic acid and the trans-10, cis-12 isomer of CLA. The amount of cis-9, trans-11 isomer of conjugated linoleic acid flowing to the duodenum was less than 260 mg/d, a value over 20 times lower than flow of trans-11 vaccenic acid indicating the importance of tissue desaturation for enhanced conjugated linoleic acid content of beef.

Animals↗
PubMed2002

By-product feeds for meat goats: effects on digestibility, ruminal environment, and carcass characteristics.

Crossbred wether goats (n = 24; 50% Boer, 6 per diet) initially averaging 27.4+/-0.4 kg were fed either wheat middlings (wheat midds), soybean hulls (soyhulls), or corn gluten feed at 1% BW (as-fed) along with orchardgrass hay (10.7% CP) offered to ad-libitum consumption for 72 d followed by 5 d total fecal collection. The Control (hay) diet was supplemented with 5.7% soybean meal to bring total dietary protein to 12.5%, by-products were brought to a higher Ca:P ratio with limestone or dicalcium phosphate to make total dietary Ca:P 1.5:1, and soybean meal was added to soyhulls to bring them up to 17% CP (wheat midds = 17% and corn gluten feed = 21% CP). Total DMI (916 g/d+/-57 or 3.2%+/-0.2 BW) did not differ (P > 0.92) among treatments. Initial BW (P = 0.25), final BW (P = 0.48), and ADG (P = 0.56) did not differ for the four treatments. Carcass weight was greater (P = 0.05) for goats fed soyhulls (16.0 kg) or wheat midds (15.6 kg) as compared with goats fed the hay diet (14.5 kg), with carcass weight from goats fed corn gluten feed being intermediate (15.3 kg, SEM = 0.3 kg). Carcass grade did not differ (P = 0.80) and averaged 5.42+/-0.4. Dressing percentage tended (P = 0.12) to be lower for goats fed the hay diet (46.4%) compared with soyhull (48.3%), corn gluten feed (48.3%), or wheat midd (48.8%) diets (SEM = 0.7). Ruminal pH was highest (P < 0.01) for goats fed the hay diet (6.52) and lowest for goats fed wheat midds (6.23) with soyhull (6.41) and corn gluten feed diets (6.35) being intermediate (SEM = 0.05). Digestibility of DM (70.1+/-2.5%), OM (70.3+/-2.6%,), CP (75.5+/-2.0%), GE (68.5+/-2.7%), NDF (68.1+/-3.0%), ADF (65.4+/-3.4%), cellulose (70.1+/-2.9%), and lignin (31.1+/-8.2%) did not differ (P > 0.15). Total ruminal VFA did not differ (86.0+/-6.1 mM, P = 0.59), but acetate:propionate ratio was higher (P < 0.01) for hay (3.1) and soyhull diets (3.3) than for corn gluten feed (2.4) and wheat midd diets (2.4, SEM = 0.11). Ruminal ammonia (mg/100 mL) was lower (P < 0.01) for goats fed hay (15.4) and soyhull diets (11.6) than those fed corn gluten feed (25.2) and wheat midd diets (23.0, SEM = 1.35). Ruminal pH was lower for goats fed the byproducts, but remained above 6. Serum urea nitrogen (mg/100 mL) averaged 21.0+/-1.0 (P = 0.11) with soyhulls tending to be lowest (19.3) and corn gluten feed tending to be highest (22.8). Soyhulls, corn gluten feed, and wheat midds appear to be viable feed ingredients for meat goat diets.

Animal Feed↗