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The objective of this study was to determine the impact of a bout of ruminal acidosis on energy metabolism of cattle unadapted to a high concentrate diet. Eleven ruminally cannulated steers [body weight (BW) = 352 kg ± 27] were blocked into 3 groups based on initial BW. Before the start of the experiment, animals were consuming a forage-based diet as well as adapted to the headbox style respiration chambers. Additionally, before the experiment, gas emission data were collected over a 24-h period when cattle received an ad libitum forage-based diet for use as a covariate in the statistical analysis. For the experiment, steers were moved into headboxes at the conclusion of a 24-h fast and subsequently received 1 of 2 treatment diets: control (CON), forage-based diet or acidosis (AC), concentrate-based diet. Steers remained in the headboxes for 48 h. Gas concentrations from each headbox were collected hourly and analyzed with an infrared photoacoustic gas analyzer. Ruminal pH, fecal pH, volatile fatty acids, and lactate were also measured during the acidosis challenge. Data were analyzed with the MIXED procedure of SAS 9.4. A treatment × day effect (P= 0.03) was observed for dry matter intake with intake being similar for both CON and AC steers on d 1 but AC steers consuming 2.02 kg less on d 2. Treatment affected ruminal pH (P< 0.01) as CON steers had a greater ruminal pH than AC steers. Greater total volatile fatty acids (P< 0.01) were observed for steers on AC treatment compared with CON. A treatment × time interaction (P< 0.01) was observed for ruminal lactate concentration with AC steers having greater concentrations from h 16 to 36. Fecal pH was affected by a treatment × time interaction (P= 0.05) as AC steers had lower fecal pH from h 24 to h 32. Over the 48-h observation period, there was a treatment × time interaction (P= 0.04) for carbon dioxide production as AC steers produced less CO2after h 24. No treatment × time interaction was detected for oxygen consumption. However, there was a time effect (P< 0.01). Respiratory quotient was not affected by treatment, day, or their interaction (P≥ 0.19). Heat production tended (P= 0.06) to be different between treatments, with AC having less heat production than CON. Thus, the effects of ruminal acidosis on gas emissions and energetics may be more transient during the time course of an acidotic bout or have a longer duration even after ruminal pH has recovered.

The objective was to characterize the effects of ruminal acidosis on rumen fermentation of steers adapted to a high concentrate diet. Cattle entering the feedlot undergo a transition period where the amount of concentrates in the diet is gradually increased to mitigate the risks of ruminal acidosis. Despite a dietary adaptation, rumen acidosis still affects feedlot cattle later in the finishing phase. Ruminally cannulated steers [n = 11; body weight (BW) = 795 kg ± 54) were blocked into 2 groups based on initial BW. Before the start of the study, cattle had been consuming a finishing diet (60% dry rolled corn, 15% modified distiller’s grains, 15% corn silage, and 10% ground corn based supplement) for more than 150 d. Steers were randomly assigned to 1 of 2 treatments: control (CON) or acidosis (ACD). For the experiment, steers were fasted for 24 h and at the conclusion received the same finishing diet. Steers on ACD steers were also ruminally dosed 0.05% BW of wheat starch on h 0 and h 12 to induce acidosis. Rumen fluid was collected every 4 h for 48 h to analyze ruminal pH, ammonia, volatile fatty acids (VFA), and lactate. Fecal grab samples were collected every 8 h for 48 h to determine fecal pH. Data were analyzed with the MIXED procedure of SAS 9.4 with the effects of treatment, time, and their interaction. A treatment × hour (P< 0.01) effect was observed for ruminal pH with the ACD steers having a lower pH than CON from h 12 to 32. Fecal pH was not affected by treatment, time, or their interaction (P≥ 0.12). Steers fed ACD had greater total VFA concentration than CON (P< 0.01). A treatment × hour interaction (P< 0.01) was observed for acetate molar proportion with CON having greater percentage acetate at h 24 through 32. Additionally, there was a treatment × hour interaction (P< 0.01) for propionate molar proportion with ACD steers having greater propionate at h 28 and 32, and then at h 40 and 44. Butyrate was not affected (P≥ 0.58) by treatment × hour or treatment. Acetate to propionate ratio (A:P) was affected by treatment × hour (P< 0.01) with CON steers having greater A:P after h 28. Rumen ammonia and lactate concentrations did not differ (P≥ 0.25) by treatment or the interaction with h. In steers adapted to a high concentrate diet, acidosis only altered ruminal fermentation in regards to ruminal pH and VFA concentrations.

Trace minerals are important in boosting the immune systems of livestock and producers should take steps to assure that they are giving the required dosage. Trace minerals include zinc, cobalt, copper, iron, selenium, molybdenum, manganese and chromium. Trace mineral requirements are determined by animal growth or reproductive response and not the immune system itself.

ABSTRACT As more and more corn gluten feed is being used in the U.S., some people in the feed industry and cattle producers themselves are having questions about the sulfur [...]

A split-plot design was used to study effects of male status (bull vs steer), zeranol implants, breed types (Angus vs Limousin) and electrical stimulation on palatability traits of five major muscles when all animals were fed to a similar fat-thickness endpoint. Warner-Bratzler shear (WBS) determinations and taste-panel evaluations were performed on the longissimus, adductor, semimembranosus, semitendinosus and biceps femoris muscles removed 24 h postmortem. Breed was the most consistent main effect difference, with Angus cattle having lower WBS values than Limousin for the longissimus and semitendinosus muscles. Angus cattle also were favored in many sensory traits. Few significant differences were noted between bulls and steers in taste-panel traits. Differences due to electrical stimulation were most evident in the longissimus muscle, with higher panel-evaluation scores, an enhancement of marbling and lean color and a lower incidence of heat ring. The implant tended to have negative effects on palatability in this trial. An overall ranking of the five muscles based on WBS from most tender to least tender was: adductor, semimembranosus, longissimus, semitendinosus and biceps femoris. Correlations of palatability traits of one muscle to other muscles within an experimental unit were found to be low.

Two steer and two lamb growth trials were conducted to measure feeding values of wheat and barley silages. Silage analyses showed that crude protein content decreased as wheat matured from the boot to dough stage. Crude fiber content was highest for boot-and milk-stage silages and lowest for dough-stage silages. In the two steer trials, performance of steers fed corn silage was significantly greater than that of steers fed Blue Boy, Arthur or Parker wheat silages. Steers fed Blue Boy-head silage in trial 1 gained 7.8% faster and consumed 7.7% more dry matter than those fed Parker-head silage. In trial 2, steers receiving barley, corn or equal parts corn and Parker-head silages performed similarly; those fed Arthur silage gained 27.5% faster, consumed 18.0% more dry matter and were 8.8% more efficient than those fed either Parker silage (head or whole-plant).In two lamb trials, lambs fed awnless wheat (Blue Boy or Arthur) or dough maturity silages out performed those fed awned wheat (Parker) or boot-, milk- or ripe-stage silages. In trial 1, sorghum silage resulted in a significantly faster and more efficient gain than any of seven wheat silages. In trial 2, lambs fed Arthur dough- or barley dough-stage silages gained faster and more efficiently than those fed Parker dough-stage silage.

Two lamb digestion trials were conducted to determine the effects of type (wheat and barley) and variety and stage of maturity (boot, milk, dough or ripe) on feeding values of cereal silages. Silage crude protein content decreased with increasing plant maturity; crude fiber was highest in the milk- and lowest in dough-stage silages. In trial 1, ration dry matter and crude protein digestibilities were not affected by variety of wheat (Parker and Blue Boy) or stage of maturity; ration crude fiber digestibility decreased (P<.05) as maturity increased. Lambs fed a sorghum silage ration retained more nitrogen (P<.05) than those fed any of seven wheat silage rations. Nitrogen retention tended to be higher in lambs fed Blue Boy wheat silages than in those fed Parker wheat silages.In trial 2, Paoli barley and Arthur and Parker wheats were each ensiled in the boot, milk and dough stages. Parker wheat and milk-stage silages were consumed in smallest amounts (P<.01) by lambs. Ration dry matter digestibility was higher (P<.05) for barley (61.8%) than for Arthur or Parker wheats (61.0 and 60.5%, respectively). Boot- and dough-stage silage rations had higher (P<.05) dry matter digestion coefficients than milk-stage silage rations (61.7, 61.4 and 60.3%, respectively. Ration crude fiber digestibility decreased (P<.01) and nitrogen-free extract digestibility increased (P<.05) as maturity increased. Nitrogen retention was not affected by type or variety of cereal grain; however, it was lowest (P<.05) in lambs fed boot-stage and highest (P<.05) in those fed dough-stage silages.

The effects of 0-, 36- and 72-mg zeranol implants were evaluated in intact and late-castrated males. A 36-mg implanted steer treatment group, castrated at the beginning of the trial, was the control. All 36-mg treatment cattle were reimplanted with a second 36-mg implant on d 112; 72-mg treatment cattle were not reimplanted. Late castration was performed on d 115 of the 210-d trial. Intact males implanted with zeranol grew more rapidly than nonimplanted males during the first 112 d, but there was no advantage to the higher dosage level. From d 112 to slaughter, bulls outgained late castrates and produced heavier carcass weights. Bulls had larger rib eyes and a lower lipid content in the 9-10-11th rib section than late castrates. Implanting increased fat thickness in intact males. Early-castrated steers had lower Warner-Bratzler shear values and greater cooking losses than bulls and late castrates, but there was no significant difference in taste panel evaluations. Implanting had little effect on testicular traits. Data from this trial indicate that delaying castration to 1 yr of age does not appear to provide economic advantages over earlier castration.

Growth, efficiency and carcass characteristics of 48 Simmental crossbred steers were fed to fat-thickness end points (FTE) of .5, 1.0 and 1.5 cm. Sixteen steers were slaughtered after reaching each assigned FTE. Feed-to-gain ratios, days on feed and weight increased with increased fat thickness. The steers were slaughtered at their assigned FTE based on backfat probe and ultrasonic scanoprobe fat-thickness measurements, which had correlations of r = .89 and r = .81, respectively, to actual carcass fat thickness. As FTE increased, hot carcass weight, total separable fat, marbling, quality grade and yield grade increased, but percentage boneless retail cuts and efficiency (feed/ gain) decreased. The amount of feed required to produce live-weight gain and separable-lean gain was determined and cattle from 1.0 to 1.5 cm FTE were less efficient than the .5- to 1.0-cm FTE cattle. Taste panel values and Warner-Bratzler shear-force values indicated that steaks from all of the FTE treatments were of acceptable quality. Days on feed, marbling, fat thickness and yield grade were not highly correlated to sensory taste-panel scores. Days on feed and fat thickness were good indicators of marbling levels, with correlations of r = .62 and r = .65, respectively.

The value of soybean meal (SBM), corn gluten meal (CGM), blood meal (BM) and fish meal (FM) in supplying N and amino acids (AA) escaping ruminal microbial degradation and disappearing from the small intestine (SI) was studied in steers using a regression approach. Replacement of corn starch in diets with protein sources resulted in decreases (P < .05) in efficiency of microbial protein synthesis. Ruminal ammonia-N (NH3-N) had the greatest increase (P< .05) when SBM was fed; BM supplementation resulted in only nonsignificant increases in ruminal NH3-N (P> .05). Soybean meal had the lowest proportion of N escaping ruminal degradation (.21). Corn gluten meal-N (.86) and BM-N (.92) escaped ruminal degradation to the greatest extent, and FM-N was intermediate (.68). Protein sources followed similar trends in providing, absorbable nonbacterial N to the SI. Thirteen (± 6.2) percent of SBM-N was absorbed from the SI; 69 (± 6.2), 68 (± 9.1) and 50 (± 10.1) % of CGM-N, BM-N and FM-N, respectively, were absorbed from the SI. Values for ruminal escape and SI availability for individual and total AA are presented. Of the essential AA (EAA), threonine, valine and isoleucine were more resistant to ruminal degradation; methionine, cysteine, histidine and arginine were more extensively degraded than the total AA supply. Of the EAA escaping ruminal degradation, cysteine, histidine and threonine tended to be less digestible, whereas arginine was more digestible in the SI than the total AA supply.

We investigated the effects of replacing dietary starch with dietary fibers of various types and particle sizes on utilization of bivalent cations by chicks. Inclusion of polyethylene powder, alfalfa cell walls, corn bran, oat bran and wheat bran into diets resulted in lower serum and tibia Zn levels. However, addition of pectin, cellulose and a xylose:gum arabic (50:50) mixture did not affect tissue Zn levels, whereas addition of 4% lignin increased serum Zn level from 2.50 to 3.44 µg/ml. Ingestion of fibers with particle sizes less than 300 µm resulted in higher serum Zn levels compared with those of particle sizes greater than 300 µm. Incorporation of 4 and 8% pectin decreased (P< 0.05) serum and tibia Mg levels. When brans were fed, kidney Mg levels were lower due to fiber additions. Inclusion of lignin, the xylose:gum arabic mixture and alfalfa cell walls resulted in lower liver Cu levels; polyethylene and solka floc had no effect on liver Cu status. Fiber did not affect tissue Ca or Fe status. Each mineral influenced by fiber type, level or particle size appeared to be affected through different mechanisms.