Impact of isoflupredone acetate treatment on clinical signs and weight gain in weanling heifers with experimentally induced Mannheimia haemolytica bronchopneumonia.

Objective: To characterize the impact of Mannheimia haemolytica infection on feed intake and weight gain in feedlot heifers and to evaluate the clinical efficacy of isoflupredone acetate administered in combination with oxytetracycline.

Animals: 96 weanling heifers in a research feedlot facility.

Procedures: Bronchopneumonia was induced by intrabronchial infusion of M haemolytica.

The role of gut tissue in the energy metabolism of growing lambs fed forage or concentrate diets.

The role of the gastrointestinal tract (GIT) in explaining the less efficient utilization of metabolizable energy (ME) in growing lambs fed forage rather than concentrate-based diets was investigated by feeding forage (legume-grass silage) and concentrate (whole shelled maize) diets, at isoenergetic intakes (ME basis), using five groups of lambs. One group of seven lambs was an initial slaughter group and of the two groups (eight lambs per group) fed each diet, one group was fed for 8 weeks, whereas the other group was fed for 16 weeks. All lambs were slaughtered between 18.

Breed effects on growth performance, carcass characteristics, fatty acid composition, and palatability attributes in finishing steers.

Crossbred steers (n = 136) were used to assess breed differences in growth performance, carcass characteristics, fatty acid composition (total lipids and phospholipids), and palatability attributes of longissimus muscle. A multiple regression model was applied to crossbreeding data to estimate genetic differences between Simmental and Red Angus at the same level of backfat finish (10 mm). Simmental spent 71 more (P < 0.

Technical note: covariance adjustment in beef cattle research.

In randomized experiments, analysis of covariance is used to increase precision of treatment comparisons. However, for factors that are observational (e.g.

Effects of forage vs grain feeding on carcass characteristics, fatty acid composition, and beef quality in Limousin-cross steers when time on feed is controlled.

Limousin-cross steers (n=135; 258+/-26 kg) were used to compare forage vs grain feeding on carcass composition and palatability attributes of beef when time on feed was controlled. Diets included a 95% alfalfa silage ration (AS) or a 68% high-moisture corn, 25% alfalfa silage ration (HMC). These were incorporated into six treatments to allow comparisons of end points based on similar days on feed or backfat finish.

Effects of ruminally degradable nitrogen intake and in vitro addition of ammonia and propionate on the metabolic fate of L-[1-14C]alanine and L-[15N]alanine in isolated sheep hepatocytes.

Isolated hepatocytes prepared from sheep fed a basal diet (bromegrass hay-corn, 50:50 wt/ wt, as-fed basis) with or without urea were used to determine the effects of added ammonia (as NH4Cl) and propionate on the partitioning of C from 1.25 mM L-[1-14C]alanine between oxidation and gluconeogenesis, and the flux of 15N from 1.25 mM L-[15N]alanine to [14N15N]urea and [15N15N]urea.

Effects of fish meal in beef cattle diets on growth performance, carcass characteristics, and fatty acid composition of longissimus muscle.

We investigated the effects of fish meal (FM) in beef cattle diets on growth performance, carcass characteristics, and fatty acid (FA) composition of longissimus muscle in 63 yearling steers (335 +/- 23 kg). High-moisture corn and alfalfa silage diets were supplemented with either a corn gluten/blood meal mixture or FM at 10% of the diet. Fish meal contained (as-is basis) 5.

Interactions between ruminal degradable nitrogen intake and in vitro addition of substrates on patterns of amino acid metabolism in isolated ovine hepatocytes.

The effects of ammonia (as NH4Cl) and propionate on the partitioning of amino acids between oxidation and gluconeogenesis were determined in isolated hepatocytes obtained from sheep fed a basal diet (50:50 bromegrass hay:corn; asfed basis) with or without urea. Hepatocyte suspensions were incubated with NH4Cl (0, 1.25, 2.

A non-linear compartmental model to describe forage degradation kinetics during incubation in polyester bags in the rumen.

A new model for describing forage degradation kinetics during incubation in the rumen using polyester bags is presented. Attention is given to dealing with the problem of deviations from exponential behaviour in the early stages of degradation by devising a function capable of representing exponential or sigmoidal trends. This is achieved by allowing part of the fractional degradation rate to vary with time of incubation, thus enabling responses other than those expected under simple first-order kinetics to be described.

A bioeconomic model for comparing beef cattle genotypes at their optimal economic slaughter end point.

A bioeconomic model of a feedlot was developed for the comparison of beef cattle genotypes under specified management and marketing conditions. The optimization behavior of commercial feedlot managers is incorporated into the model using optimum economic rotation theory. The days spent in the feedlot (rotation) by a group of animals are derived using this theory so as to maximize an objective function.

Effects of forage particle size and long hay for cows fed total mixed rations based on alfalfa and corn.

A 2 x 2 factorial arrangement of treatments, in which particle length of alfalfa silage in the TMR and supplementary long alfalfa-grass hay were the factors, was used to determine whether hay benefits lactating cows and whether its effects depend on fibrosity of the main forage source. Without supplementary hay, TMR contained 45% forage, including corn silage, and 26 to 27.5% NDF.

A colorimetric method for the quantitation of uronic acids and a specific assay for galacturonic acid.

A method of quantitating uronic acids and uronic acids from pectin in particular is described. The method uses carbazole in 80% sulfuric acid with borate ions added. The assay is carried out at 60 degrees C.

Characterizing rumination patterns of dairy cows using spectral analysis.

Spectral analysis techniques were used to characterize the cyclical variation in rumination behavior of cows. Four Holstein cows were fed twice daily a diet of 60% high-moisture shelled corn-based concentrate, 15% first-cut alfalfa-grass hay and 25% second-cut alfalfa silage. The number of minutes that each cow spent ruminating was determined for 15-min intervals during six consecutive days.

Effects of fiber source and method of feeding on chewing activities, digestive function, and productivity of dairy cows.

This experiment was conducted to evaluate the effects of supplementing a silage-based diet with hay on chewing, digestive function, and productivity of dairy cattle. Eight multiparous rumen-cannulated Holstein cows were fed, in a crossover design, three diets containing 60% high moisture shelled corn-based concentrate and either: 1) 40% alfalfa silage (37% DM; 21% CP; 44% NDF); 2) 25% alfalfa silage and 15% long alfalfa grass hay (16% CP; 57% NDF) with hay offered with 15% chopped alfalfa grass hay. Milk production (kg/d) was increased from 17.

Effects of dietary neutral detergent fiber concentration and supplementary long hay on chewing activities and milk production of dairy cows.

Effects of dietary NDF concentration on chewing and productivity were assessed using silage-based diets with and without supplemental long hay. Twelve Holstein cows (125 d postpartum) were used in a double 6 x 6 Latin square to evaluate six diets formulated using high moisture shelled corn and alfalfa silage (37% DM, 23% CP, 48% NDF) to provide three concentrations of NDF: 26, 30, and 34%. At each concentration, an alternative diet was formulated by substituting 15% of the silage DM with an equivalent amount of long alfalfa grass hay (14% CP, 61% NDF).

Response of dairy cows in early lactation to sodium hydroxide-treated soybean meal.

To determine effects of protein and rumen degradability in rations for early lactation cows, four diets (44:56 roughage:concentrate) were formulated to contain 15 or 17.5% CP and supplemental protein from untreated or NaOH-treated soybean meal. Diets were allocated to 34 multiparous Holstein cows from d 22 to 91 of lactation.

Reproductive performance of lactating Holstein cows fed supplemental beta-carotene.

Fifty-six Holstein cows were used in a replicated study to determine whether supplemental beta-carotene improved reproductive performance. Each of two replicates was of completely randomized design with 2 X 2 factorial arrangement of two diets with or without beta-carotene supplementation. On a dry matter basis, diet 1 was 5% hay, 20% haylage, 25% corn silage, and 50% concentrate.

Protease activities of rumen protozoa.

Intact, metabolically active rumen protozoa prepared by gravity sedimentation and washing in a mineral solution at 10 to 15 degrees C had comparatively low proteolytic activity on azocasein and low endogenous proteolytic activity. Protozoa washed in 0.1 M potassium phosphate buffer (pH 6.

Effects of buffers on ruminal rate of passage and degradation of soybean meal in steers.

Eight rumen-fistulated steers were randomly assigned to medium- and high-concentrate diets supplemented with 0, .75, 2.5 and 5% of either sodium bicarbonate or an artificial saliva salts mixture.

Effect of sodium bicarbonate on rate of passage and degradation of soybean meal in postpartum dairy cows.

Effects of sodium bicarbonate on rate of passage and disappearance of soybean meal from the rumen were determined in a change-over experiment with eight cows. Experimental diets containing 50 or 60% roughage were fed over five 21-day periods with four cows per diet. Sodium bicarbonate at 1.

Proteolytic activity of rumen microorganisms and effects of proteinase inhibitors.

Proteolytic activity of the bovine rumen microflora was studied with azocasein as the substrate. Approximately 25% of the proteolytic activity of rumen contents was recovered in the strained rumen fluid fraction, and the balance of the activity was associated with the particulate fraction. The proportion of proteinase activity associated with particulate material decreased when the quantity of particulate material in rumen contents was reduced.

Effect of ensiling whole plant corn on voluntary intake, rumen fermentation, retention time and rate of digestion in steers.

The study was designed to determine whether products of fermentation in corn silage could limit its voluntary intake. Six rumen-cannulated Hereford steers were assigned randomly to diets of corn silage (CS) and dried corn forage reconstituted either with water (DC + W) or with extracts from corn silage (DC + CSE) according to a crossover design with three experimental periods. During each period, steers were fed ad libitum for 18 days and then restricted to 65 g DM/kg BW.