Alkaline hydrogen peroxide treatment unlocks energy in agricultural by-products.

Lignocellulosic residues (wheat straw, corncobs, and cornstalks) were treated with a dilute alkaline solution of hydrogen peroxide and suspended in cattle rumen in situ to measure microbial degradation. The rate and extent of dry matter disappearance were markedly increased as a result of the treatment. Results in vivo indicate that this treatment increases the fermentability of wheat straw structural carbohydrates such that this agricultural by-product may be considered an acceptable energy source for the ruminant animal. Treatment of wheat straw allowed more complete bacterial colonization and more rapid degradation of the cell wall.

Effect of ractopamine hydrochloride (Optaflexx) dose and duration on growth performance and carcass characteristics of finishing steers.

Three experiments evaluated the effects of ractopamine hydrochloride (RAC) dose and duration on growth performance and carcass characteristics of feedlot steers. In total, 1,509 crossbred steers (530 kg initial BW [SD 22]) were used in a randomized complete block design using a 3 × 3 factorial treatment structure. Treatments consisted of RAC dose (0, 100, or 200 mg/steer daily) and duration (28, 35, or 42 d) of RAC feeding prior to harvest. Initiation of RAC dose was staggered (7 d apart) based on RAC duration, which resulted in common days on feed among treatments. Data from the 3 experiments were combined for statistical analyses. There were no RAC dose × duration interactions ( ≥ 0.85) for growth performance. Live final BW was not different ( ≥ 0.24) as RAC dose increased. Dry matter intake linearly decreased ( < 0.01) as RAC dose increased. Live ADG and G:F linearly increased ( ≤ 0.01) as RAC dose increased. Carcass-adjusted ADG and G:F linearly increased ( ≤ 0.02) as RAC dose increased. Compared with steers fed 0 mg RAC/steer daily, G:F was improved by 5.0 and 13.0% when steers were fed 100 ( = 0.31) and 200 ( = 0.01) mg RAC/steer daily, respectively. Hot carcass weight tended ( = 0.10) to linearly increase as RAC dose increased, with carcasses from steers fed 100 ( = 0.38) and 200 ( = 0.10) mg RAC/steer daily being 2.2 and 4.1 kg heavier, respectively, than carcasses from steers fed 0 mg RAC/steer daily. Increasing RAC dose linearly ( < 0.01) increased LM area and linearly ( = 0.02) decreased marbling score. Live final BW was not different ( ≥ 0.60) among RAC durations. Carcass-adjusted final BW, ADG, and G:F were not different ( ≥ 0.41) as RAC duration increased. Carcass traits did not differ ( ≥ 0.18) among RAC duration. Feeding 200 mg RAC/steer daily improved ADG, feed efficiency, and HCW. Increasing the feeding duration of RAC had no effect of growth performance or carcass characteristics. These data indicate that feeding 200 mg RAC/steer daily for 28 d improves steer growth performance.

Effect of salinomycin level on nutrient digestibility and ruminal characteristics of sheep and feedlot performance of cattle.

A sheep digestion trial and two feedlot trials with cattle were conducted to study effects of an ionophore, salinomycin, on nutrient digestibility, ruminal metabolism and cattle performance. In trial 1, addition of salinomycin at 5.5, 11 or 22 ppm to 60% concentrate diets fed to ruminal-cannulated rams had no effect (P greater than .05) on apparent digestibility of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF) or starch in comparison with control diets. Apparent nitrogen (N) digestibility was increased (P less than .05) in animals fed salinomycin. Salinomycin did not affect total volatile fatty acid (VFA) concentrations in the rumen, but resulted in a linear (P less than .05) increase in molar proportion of propionate and a linear (P less than .05) decrease in molar proportions of acetate and butyrate and in acetate:propionate ratios. Shifts in VFA proportions were fully expressed within 4 d after salinomycin was added to the diet. In trial 2, salinomycin was added at 5.5, 11, 22 or 33 ppm to 85% concentrate diets fed to finishing steers. Salinomycin level had a quadratic effect (P less than .05) on daily weight gain and resulted in a quadratic (P less than .05) decrease in feed intake with a resultant average improvement of 10.3% in feed efficiency. Salinomycin (5.5, 11, 16.5 or 22 ppm) and monensin (22 ppm) were added to 90% concentrate diets in trial 3 and produced increased rates of gain without affecting feed intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Feedlot performance and carcass characteristics of Holstein steers as affected by source of dietary protein and level of ruminally protected lysine and methionine.

The objective of this study was to determine the effects of source of dietary CP and level of ruminally protected lysine and methionine (RPLM) on feedlot performance and carcass characteristics of Holstein steers during a growing-finishing trial (266 d). A total of 168 Holstein steers (182.7 +/- 27.5 kg) were used in a completely randomized design experiment (eight treatments; three pens of seven steers/treatment). Steers were given ad libitum access to high-concentrate diets (13% CP) containing 71% whole shelled corn, 10% corn silage, 4% condensed distillers solubles, and 15% protein supplements (DM basis). Treatments were arranged as a 2 x 4 factorial. The main factors were two sources of dietary CP and four levels of RPLM. The sources of dietary CP were soybean meal (SBM) or SBM and urea (SBM-U). Urea-N replaced 50% of SBM-N in the SBM-U diet. The levels of RPLM were 0, 5, 10, and 15 g per steer daily. No interactions (P > .10) between source of dietary CP and level of RPLM were observed for feedlot performance or carcass characteristics. Feedlot performance showed an advantage (P < .10) to feeding SMB during the first 84 d of the trial and an advantage to feeding SBM-U during the last 98 d of the trial. However, feedlot performance for the whole trial and carcass characteristics (except for fat thickness) were not affected (P > .10) by the source of dietary CP. Steers fed diets containing SBM-U had 12% less (P < .10) fat thickness than those fed diets containing SBM. Supplementation of diets with increasing levels of RPLM did not affect (P > .10) ADG or carcass characteristics. However, DMI and gain:feed showed cubic (P < .10) responses to increasing dietary level of RPLM. Supplementation of RPLM at the 10 g/d level improved gain:feed by 12% during the last 98 d of the trial, and this was a direct response to the cubic effects of RPLM on DMI. Results suggest a cost advantage for replacing 50% of SBM-N with that from urea in high-corn diets without negative effects on feedlot performance or carcass characteristics of growing-finishing Holstein steers with extended feeding periods (266 d). These types of diets seem to meet the amino acid requirements and are not limiting in lysine and methionine.

Effects of feed intake and dietary level of wet corn gluten feed on feedlot performance, digestibility of nutrients, and carcass characteristics of growing-finishing beef heifers.

The objective was to compare the relative energy value of wet corn gluten feed (WCGF) to that of corn in a feedlot situation when diets were initially offered ad libitum (AL) or at restricted feed intake (RFI; 80% of AL). In a completely randomized block (pen location) design experiment, 144 beef heifers (204.1 +/- 18.2 kg) were used (six treatments; three pens of eight heifers/treatment). Treatments were levels of WCGF (on DM basis) in corn silage-based diets (AL; 25 or 50% WCGF) or high-moisture corn-based diets (RFI; 0, 25, 50, or 75% WCGF) during the growing phase (127 d). During finishing (84 d), all diets were offered AL and contained 5% corn silage by replacing corn silage with high-moisture corn in diets that were offered AL. Heifers that were initially at AL had similar (P > .1) feedlot performance (during growing and during the whole trial), digestibility of nutrients (OM, NDF, CP, and GE), and carcass characteristics. During finishing, however, these heifers had better (P = .06) ADG and gain:feed when 25% WCGF was fed. Heifers that were initially at RFI showed a linear decrease (P < .01) in ADG and gain:feed during growing with increasing dietary level of WCGF. However, increasing dietary level of WCGF resulted in a quadratic (P = .02) response in ADG and gain:feed during finishing and also in a quadratic (P = .07) response in ADG and a linear (P = .005) decrease in gain:feed during the whole trial. These quadratic responses indicated that the best performance was achieved at the 25 and 50% levels of WCGF. The decrease in cumulative gain:feed was only 3.5% at the 25 and 50% levels of WCGF but it was 11.4% at the 75% level. Increasing the level of WCGF in diets of heifers that were initially at restricted feed intake did not affect (P > .1) digestibility of nutrients but it improved some carcass characteristics linearly, decreasing fat thickness (P = .04), liver abscess (P = .02), and yield grade (P = .13). Results suggest that WCGF can substitute up to 25 or 50% of dietary DM without negative effects on feedlot performance, digestibility of nutrients, or carcass characteristics. In addition, restricting feeding during growing may be strategy that improves the utilization of WCGF at these levels.

Evaluation of soybean meal, corn gluten meal, blood meal and fish meal as sources of nitrogen and amino acids disappearing from the small intestine of steers.

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 less than .05) in efficiency of microbial protein synthesis. Ruminal ammonia-N (NH3-N) had the greatest increase (P less than .05) when SBM was fed; BM supplementation resulted in only nonsignificant increases in ruminal NH3-N (P greater than .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.

Effects of ammoniation of tall fescue on phenolic composition, feed intake, site and extent of nutrient digestion and ruminal dilution rates of steers.

Tall fescue hay (H) supplemented with corn and urea (HU) or corn gluten meal (HCGM) and ammoniated tall fescue hay supplemented with corn (AH) or corn gluten meal (AHCGM) were fed to steers in two 4 X 4 Latin-square trials. Diets were fed to four Angus-Hereford steers (550 kg) at equal intakes in trial 1 and to four Hereford steers (350 kg) at ad libitum intakes in trial 2. Ammoniation reduced cell wall concentrations of p-coumaric acid and ferulic acid by 48 and 67%, respectively. Concentrations of other phenolics were also reduced. Apparent total tract digestibilities of vanillin, p-coumaric acid and ferulic acid were lower (P less than .05, .001 and .01, respectively) when nontreated hay was fed in trial 1, but were not different between hay types in trial 2. In trial 1, greater negative intestinal digestibilities of p-coumaric acid (P less than .001) and vanillin (P less than .05) occurred for steers fed HU and HCGM vs AH and AHCGM diets. Digestibilities of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were greater (P less than .001) for steers fed ammoniated hay diets in both trials and greater (P less than .05) for HCGM vs HU in trial 1. More than 96% of the NDF and ADF digested by steers in trial 1 was digested in the stomach. Intakes of digestible NDF and ADF, but not indigestible NDF or ADF, were higher (P less than .001) for steers fed AH and AHCGM in trial 2. In situ dry matter disappearance rate of ammoniated hay was greater (P less than .05) than that of nontreated hay, but rate of cotton thread disappearance from bags suspended in the rumen of steers fed the various diets was similar among treatments. In both trials, feeding ammoniated hay resulted in higher (P less than .05) ruminal concentrations of acetate and higher (P less than 0.05) acetate:propionate ratios. Ruminal liquid dilution rates were lower (P less than .05) for steers fed AH and AHCGM in trial 1, but were not different in trial 2. Ruminal dry matter concentration and solids dilution rate were not affected by diet in either trial. The results are interpreted to indicate that increased intake of ammoniated hay is a result of increased rate and extent of fiber digestion.

Low-quality roughages in high-concentrate pelleted diets for sheep: digestion and metabolism characteristics as affected by corncob and(or) rice hull additions.

Two trials were conducted to determine effects of feeding corncobs, rice hulls or a combination of both on nutrient digestion and flow of digesta through the gastrointestinal tract of multiple-cannulated sheep (55-kg Rambouillet X Dorset rams; trial 1; 4 X 4 Latin square) as well as ruminal, digestive and metabolic characteristics of early-weaned lambs (24.1-kg crossbred rams; trial 2; randomized complete block design; 3 periods) fed pelleted 75% concentrate-25% roughage diets. In trial 1, apparent total tract dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) digestibilities decreased and N digestibility increased as percentage of dietary corncobs decreased and percentage of rice hulls increased. Site of NDF digestion appeared to shift from the upper to the lower digestive tract as percentage of corncobs decreased and percentage of rice hulls increased. In trial 2, apparent DM digestibility decreased as corncobs were replaced with rice hulls in the diet. Neutral detergent fiber digestibility was not affected by diet except in larger lambs at higher intakes, with NDF digestibility generally decreasing as percentage of dietary rice hulls increased. Nitrogen digestibility was not affected by replacing corncobs with rice hulls in the diet. Ruminal pH decreased as rice hulls replaced corncobs in the diet. These data are interpreted to indicate that rice hulls can be effectively substituted for corncobs in sheep diets when added at levels up to 25% of the total diet.

Comparison of the effects of three methods of harvesting and storing alfalfa on nutrient digestibility by lambs and feedlot performance of steers.

Two lamb digestion and three steer growth experiments were conducted to study the feeding value of alfalfa harvested as direct-cut silage (DCS) with grain added prior to ensiling or as low-moisture silage (LMS) or hay with grain added at feeding. In all experiments, alfalfa-grain mixtures contained approximately 50% alfalfa and 50% concentrate (dry matter [DM] basis). In Exp. 1, lambs fed DCS alone consumed less DM than lambs fed LMS or hay alone or any of the alfalfa-grain mixtures. Apparent digestibilities of DM and fiber components were higher (P less than .05) for DCS than for LMS or hay. Lambs that were fed LMS digested more (P less than .05) DM and fiber components than lambs fed hay. Addition of grain resulted in increased (P less than .05) DM digestibility and decreased (P less than .05) digestibilities of neutral detergent fiber and acid detergent fiber. In Exp. 2, growing steers (271 kg) fed DCS-grain had increased (P less than .05) weight gains compared with steers fed hay-grain. Steers fed any of the alfalfa-grain mixtures gained weight more rapidly (P less than .05) than steers fed corn silage (CS)-based diets. In a third experiment, finishing steers (283 kg) fed DCS-grain, LMS-grain, hay-grain or CS-based diets performed similarly (P greater than .05), although steers fed DCS-grain had higher (P less than .05) dressing percentages and yield grades than steers that were fed the other three diets and were fatter (P less than .05) than those fed LMS-grain or CS. In Exp. 4, lambs fed DCS-grain or LMS-grain had higher (P less than .05) apparent DM and organic matter digestibilities than lambs fed CS-based diets with similar forage:grain proportions. In Exp. 5, finishing steers (326 kg) fed DCS-grain gained similarly (P greater than .05) to steers fed LMS-grain or an 85% concentrate diet based on high-moisture corn. Steers fed CS diets had lower (P less than .05) gains and increased (P less than .05) feed per gain compared with steers fed DCS-grain, LMS-grain or high-moisture corn.

Effects of feeding a return chewing gum/packaging material mixture on performance and carcass characteristics of feedlot cattle.

Seventy-two Simmental-cross growing steers (219 +/- 2.4 kg initial BW) were used in a randomized complete block design to evaluate the effects of feeding a return chewing gum/packaging material mixture (G/P) on feedlot performance, carcass characteristics, sensory attributes of meat, and mineral content of beef liver and muscle. Animals were allotted by weight to 12 pens (six/pen). Each pen was assigned one of three dietary treatments: 1) 0% G/P (control), 2) 20% G/P, or 3) 30% G/P (% G/P on a DM basis). Steers were fed their respective diets for an 84-d growing phase and a 112-d finishing phase. The G/P replaced corn silage and corn in the growing and finishing phases, respectively. Eighteen steers (six/treatment) were randomly selected for slaughter at the end of the finishing phase, and carcass measurements, sensory attributes of meat, and mineral content of liver and longissimus muscle were measured. During the growing phase, steers fed G/P-containing diets had improved (P < .01) daily DMI, ADG, and gain:feed ratios (G:F) compared with controls. However, due to compensatory gain and the fact that G/P replaced corn in the finishing phase, control steers had increased (P < .01) ADG and improved (P < .05) G:F vs steers fed G/P-containing diets. Over the entire study (growing and finishing phases) steers fed diets containing G/P and the control had similar performance. Amount of G/P in the diet had no effect (P > .05) on carcass characteristics. Steaks from steers fed 20% G/P had improved (P < .01) juiciness compared with steaks from steers fed 30% G/P; no other sensory attributes were affected. Aluminum, zinc, and barium content of longissimus muscle and liver were within the normal expected ranges for all treatments. These data indicate that G/P can safely replace at least 30% of growing and finishing diets without impairing feedlot performance or carcass merit.

Digestion kinetics of alfalfa and wheat straw assuming heterogeneity of the potentially digestible fraction.

Although it is recognized that the potentially digestible fraction of substrates in the rumen is heterogeneous in composition, most deterministic models that describe ruminal in situ digestion assume existence of only one or two homogeneous fractions of potentially digestible material. Alternatively, a stochastic model based on heterogeneity of substrate has been developed, although its validity has not been determined. To evaluate such a model, alfalfa hay and wheat straw were physically fractionated by dry sieving. Dacron bags containing these fractions were incubated in the rumen of a steer and the residue that remained was analyzed sequentially for DM, NDF, ADF, ADL, and acid detergent insoluble ash. Digestion kinetics of chemical fractions were determined by simultaneous analysis of the digestion profiles of DM, NDF, ADF, ADL, and acid detergent insoluble ash. The weighted mean and variance of the fractional digestion rate constant were .083 h-1 and 4.7 x 10(-4) h-2 for alfalfa and .021 h-1 and 2.4 x 10(-5) h-2 for wheat straw, respectively. In contrast, fitting DM data to a stochastic model assuming heterogeneous rates, the mean and variance of the fractional digestion rate were .078 h-1 and 8.3 x 10(-11) h-2 for alfalfa and .018 h-1 and 5.3 x 10(-12) h-2 for wheat straw, respectively. Because the estimates of the variance approached zero for the stochastic model, it is implied that this model reduced to a model involving a single fractional digestion rate. It is concluded that parameter estimates obtained from a stochastic model do not necessarily have a biological meaning.

Alkali treatment of cereal grains. II. Digestion, ruminal measurements and feedlot performance.

Two trials were conducted to determine the effects of feeding alkali-treated corn on various metabolic and performance characteristics of cattle. In the first trial, four ruminally-fistulated cows were fed high moisture corn (HMC) in the following forms: whole, rolled, sodium hydroxide (NaOH)-treated and ammonium hydroxide-treated. The corn was fed as 75% of the diet (dry matter basis) in four 15-day feeding periods in a 4 x 4 Latin square design. NaOH-treated HMC produced the highest dry matter digestibility (P less than .05), the highest rumen pH (P less than .05), the highest ruminal fiber digestion (P less than .05) and the highest fecal pH (P less than .05). Rolled HMC produced the lowest rumen pH (P less than .05) and lowest fiber digestion (P less than .05). Ammonium hydroxide-treated HMC produced no response in comparison to whole HMC and had the lowest rate of passage (P less than .05). Fecal starch, fecal water content, rumen fill and rumen ammonia were unaffected by treatments. In the second trial, 90 yearling steers were randomly allotted to five groups of 18 (six steers per pen). Steers were fed ad libitum a diet of 20% corn silage, 5% supplement and 75% corn as dry shelled corn, whole HMC, rolled HMC, NaOH-treated dry shelled corn or NaOH-treated HMC. There were no treatment effects on daily dry matter intake. Cattle fed either of the NaOH-treated corns had lower (P less than .05) average daily gains and poorer (P less than .05) feed efficiencies. No treatment effect was apparent for any carcass characteristic measured except yield grade, which was lower (P less than .05) for steers fed NaOH-treated HMC. Whole HMC produced the highest (P less than .05) fecal pH values while both NaOH treatments produced lower (P less than .05) fecal pH values than the other treatments.

Effect of sodium hydroxide treatment on rate of passage and rate of ruminal fiber digestion.

Ruminally fistulated lambs were used to measure the effect of sodium hydroxide treatment on rate of passage and rate of ruminal fiber digestion. Corncobs were raised to 60% moisture and treated to a final concentration of 0, 2.5, 5.0, 7.5 and 10.0% NaOH on a dry matter basis. The diets fed contained 80% cobs and 20% supplement, giving a complete mixed diet containing 0, 2.0, 4.0, 6.0 and 8.0% NaOH (dry basis). Chromic oxide was used as an external marker, and rumen samples were collected at 3, 6, 12, 24, 48 and 96 hr post-dosing. As level of NaOH treatment increased, rate of passage increased linearly (P less than .05). Mean ruminal retention time decreased from 32.4 hr for the control diet to 20.7 hr for the 8% NaOH diet. When rate of passage was regressed against NaOH level, the slope of the line was .142%/hr per unit NaOH, with r2 = .733. In another trial, sodium concentrations equal to the 4% NaOH diet were obtained by the addition of 7.3% NaCl to the basal diet. Rates of passage for lambs fed the diet containing NaCl were faster (P less than .05) than for lambs fed the control diet but slower (P less than .05) than for lambs on the 4% NaOH diet. These data suggest that both sodium intake and NaOH treatment affect rate of passage and are additive. Nylon bags containing .15 g cotton were used to measure the rate of ruminal fiber digestion in lambs fed the five NaOH-treated diets. Bags were removed from the rumen after 12, 24, 36 and 48 hr, and the loss in weight were used to estimate ruminal digestion. As level of NaOH increased, the rate of ruminal cotton digestion decreased linearly (P less than .05). When rate of cotton digestion was regressed against NaOH level, the slope of the line was -.488%/hr per unit NaOH, with r2 = .934.

Comparison of two forms and two levels of lasalocid with monensin on feedlot cattle performance.

One growth and two finishing trials were conducted with beef steers to compare lasalocid sodium and monensin sodium. Pure lasalocid, mycelia-cake lasalocid and monensin, each added individually to commercial protein supplement blocks at 880 mg/kg, depressed (P greater than .05) block intake so that approximately 100 mg of each additive were consumed daily by each animal. Daily gain, feed intake and feed efficiency for steers receiving blocks containing additives did not differ from the corresponding measures for steers receiving control blocks. No differences were observed in diet dry matter digestibility, as determined with acid-insoluble ash as an internal marker. Both forms of lasalocid and monensin reduced (P greater than .05) the incidence and concentration of coccidia oocysts. By day 40, only one steer on each of the additive treatments was shedding oocysts (4.2% of additive-supplemented animals), compared with 41.5% of the control steers. During trial 2, steers fed pure lasalocid gained faster and more efficiently (P greater than .05) than those fed the mycelia-cake lasalocid, monensin or control diets. The improvement in feed efficiency over the control value was 10.0, 3.4 and 4.0% with pure lasalocid, mycelia-cake lasalocid and monensin, respectively (P greater than .05). Steers fed mycelia-cake lasalocid had higher (P greater than .05) dressing percentages than those fed pure lasalocid or monensin. Dressing percentage was the only carcass measurement affected. In trial 3, lasalocid at 30 and 45 g/ton and monensin at 30 g/ton improved (P greater than .05) feed efficiency by 7.5, 11.0 and 8.2%, respectively. No significant differences in incidence or concentration of oocysts were observed between treatment groups in trial 3, probably because steers were in slatted floor pens.

Influence of zeranol implants and electrical stimulation on the palatability traits of five muscles in Angus and Limousin bulls and steers.

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.

Effect of testosterone propionate on performance and carcass characteristics of heifers and cows.

Two experiments were conducted to evaluate the effect of testosterone on growth and composition of cattle. In the first experiment, crossbred yearling heifers (n = 48) were assigned to four treatments: 1) control (no implant), 2) Synovex-H implants on d 1 and 84, 3) one testosterone propionate implant administered on d 1 and a second on d 84 and 4) two testosterone propionate implants administered on d 1. Heifers were fed a high-energy diet for the 157-d study. Implanting with the high-testosterone treatment improved (P less than .05) daily gain and feed efficiency compared with the other treatments. Marbling score was reduced (P less than .05) with the high-testosterone treatment. In Exp. 2, mature cows (n = 36) were assigned to one of three feeding periods (0, 42, or 84 d) with the cows fed 42 or 84 d subdivided into two groups (implanted with testosterone propionate or nonimplanted control). Cows were fed a high-energy diet and slaughtered at the end of each feeding period. Testosterone did not influence (P greater than .05) feedlot performance. Increased time on feed reduced (P less than .01) daily gain (live weight basis) and feed efficiency but did not influence feed intake. Testosterone treatment had little influence on the fat and moisture contents of the carcass soft tissue or on the palatability characteristics of loin steaks. Time on feed increased lean muscle mass and carcass fat (P less than .05). Sensory traits were improved at 42 d on feed (P less than .05), but no further sensory improvement was observed at 84 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of roughage particle size on site of nutrient digestion and digesta flow through the gastrointestinal tract of sheep fed corncob-concentrate diets.

An experiment examining nutritional effects of dietary corncob particle size was conducted using ruminal-, duodenal- and ileal-cannulated sheep in a 4 X 4 Latin square design. Site of nutrient digestion and digesta flow were the principal criteria evaluated. Analyses of dry matter (DM), N, starch and neutral detergent fiber (NDF) were performed on feed, feces and digesta samples. Chromic oxide-impregnated paper was used as an external marker to estimate digestibilities at different sites along the gastrointestinal tract. Ruminal pH and volatile fatty acid molar proportions were also determined. All diets (74.9% concentrates: 25.1% corncobs) were pelleted and were similar in ingredient composition but varied in corncob particle size (corncob mean particle sizes were 6.5, 5.4, 1.4 or .8 mm). Dietary crude protein levels differed little among treatments. Starch concentration was higher in diets containing the larger corncob particles while NDF, acid detergent fiber (ADF), cellulose and hemicellulose concentrations were lower in diets containing larger particles, suggesting a reaction between starch and fiber moieties during the pelleting process. Starch flow past the duodenum decreased (P less than .05) as dietary corncob particle size decreased. Apparent NDF digestion before the duodenum was highest for sheep fed diets containing 1.4-mm corncobs (P less than .05). Apparent starch digestion in the small intestine decreased (P less than .05) as dietary corncob particle size decreased. A considerable amount of NDF was apparently digested in the small intestine of sheep consuming diets containing 5.4- and .8-mm corncobs. Likewise, a substantial amount of NDF was apparently digested in the large intestine. Few differences in apparent total tract digestibilities were noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of roughage particle size on ruminal, digestive and metabolic characteristics of early-weaned lambs fed pelleted corncob-concentrate diets.

Two experiments were conducted to determine effects of feeding corncobs of various mean particle size (MPS) on ruminal, digestive and metabolic characteristics of early-weaned lambs fed pelleted 74.9% concentrate:25.1% corncob diets. The MPS of corncobs in diets was 6.5, 5.4, 1.4 and .8 mm, respectively. As particle size decreased, percentage starch decreased and percentage neutral detergent fiber (NDF), acid detergent fiber (ADF) and cellulose increased. In Exp. 1, 28 crossbred rams (seven/treatment, avg initial wt, 15.3 kg) were used in a randomized complete-block design. In Exp. 2, lambs from Exp. 1 were re-weighed (avg initial wt, 16.8 kg) and fed the same diets as in Exp. 1. In Exp. 1 and 2, lambs ingested dry matter (DM) equal to 2.68 and 3.74% of body weight, respectively. In Exp. 1, apparent DM digestibility was unaffected by corncob MPS; however, in Exp. 2, DM digestibility was highest (68.8%) for lambs fed the 6.5-mm diet and lowest (63.8%) for those fed the .8-mm diet. Apparent starch digestibility was high (greater than 98.8%) in both experiments. Neutral detergent fiber and ADF digestibilities were highest for lambs fed the 1.4-mm diet (50.5 and 43.6%, Exp. 1; 39.6 and 28.9%, Exp. 2). A dramatic increase (6.8 to 39.1%) in acid detergent lignin (ADL) digestibility was observed in Exp. 1 as corncob MPS decreased. In Exp. 2, ADL digestibilities were similar for lambs fed the 6.5-, 5.4- or 1.4-mm diets (avg value, 5.9%) and highest for those fed the .8-mm diet (29.7%). Nitrogen metabolism was unaffected by corncob MPS. In Exp. 1, digestible energy intake, corrected for urinary losses, did not differ among treatments but in Exp. 2, lambs consuming the 6.5-mm diet had higher corrected digestibility energy intakes (1,926.6 kcal/d) than did those fed other diets (avg, 1,832.4 kcal/d). Ruminal pH sampled 4 h post-feeding was highest for lambs consuming the 6.5-mm diet (6.25) in Exp. 1 and the 1.4-mm diet (5.89) in Exp. 2. Lowest ruminal pH (5.30 and 5.36, respectively) was for lambs consuming the .8-mm diet in Exp. 1 and the 5.4-mm diet in Exp. 2. Ruminal lactate concentrations were variable within and among treatments. Total ruminal volatile fatty acid (VFA) concentrations were similar across treatments but in Exp. 2, there was a shift in molar proportions from acetate to propionate as corncob MPS decreased.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of dietary alfalfa:orchardgrass hay and lasalocid on nutrient utilization by gravid sows.

Twenty-four third- and fourth-parity crossbred gravid sows were housed in metabolism stalls and randomly allotted to four dietary treatments: corn-alfalfa:orchardgrass hay (46%; CH), CH plus lasalocid (CHL), corn-soybean meal (CS) or CS plus lasalocid (CSL). Daily feed intake was 2.36 kg for CH- and CHL-fed sows and 1.66 kg for CS- and CSL-fed sows. Lasalocid intake was 110 mg X sow-1 X d-1. Total feces and urine were collected during two 5-d collection periods, 40 and 80 d postcoitum. Digestible energy (DE), metabolizable energy (ME), nitrogen (N) retention, dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibilities, and retention of calcium (Ca), total phosphorus (P), magnesium (Mg), sodium (Na) and potassium (K) were determined. Percentage DE and ME were greater (P less than .0001) for CS- and CSL-fed sows (88.3 and 83.4%) than for CH- and CHL-fed sows (65.2 and 61.3%). Lasalocid did not influence (P greater than .05) DE and ME values but decreased (P less than .01) the ME:DE ratio. Percentage N digestibility was greater (P less than .0001) for CS- and CSL-fed sows (85.7%) than for CH- and CHL-fed sows (60.8%), but there was no significant difference in N retention, expressed as a percentage of N intake. Lasalocid increased (P less than .03) percentage N digestibility; however, the diet X additive interaction decreased (P less than .005) grams N retained X sow-1 X d-1 for CSL-fed sows. The CH- and CHL-fed sows digested more grams of DM, NDF and ADF but had lower percentage digestibilities of DM and fiber fractions than did CS- and CSL-fed sows. The diet X additive interaction decreased (P less than .05) percentages of Ca, P and K digested and decreased (P less than .05) grams mineral retained (Ca, P, Mg and K) and mineral retained expressed as a percentage of intake for CSL-fed sows. Results indicate that alfalfa:orchardgrass hay and lasalocid influenced energy, fiber, nitrogen and mineral utilization by gravid sows.

Effects of heat and alcohol treatments of soybean meal on nitrogen utilization by sheep.

Soybean meal (SBM) was treated with aqueous solutions of ethanol or propanol at room temperature or at 80 C to study treatment effects on SBM-N solubility and utilization by sheep. Soybean meal was soaked in an excess of 70% (v/v) ethanol at 80 C (ET-80), 70% ethanol at 23 C (ET-23) or 70% propanol at 80 C (PR-80). Nontreated SBM and nontreated SBM heated at 80 C without alcohol treatment (NT-80) served as controls. Nitrogen solubility in McDougall's buffer was lowest (P less than .05) for PR-80 and ET-80 (2.2 and 4.7% of total N, respectively), intermediate (P less than .05) for ET-23 (9.0%), greater (P less than .05) for nontreated SBM (36.2%) and highest for NT-80 (40.2%). In an situ study using three ruminally cannulated cows and two bags per treatment per animal per removal time, more (P less than .05) N remained in in situ bags after 3, 6, 9 and 12 h incubation for ET-23, ET-80 and PR-80 than for nontreated SBM and NT-80. A lamb metabolism trial, using 15 lambs in each of two periods, compared nontreated SBM, ET-23, ET-80, PR-80 and urea as N supplements. Nitrogen retention was higher (P less than .02) for lambs fed SBM treatments compared with urea. When the same N supplements were fed to wethers in a 5 X 5 Latin square experiment and duodenal N flow was measured, non-ammonia non-bacterial N flow was higher (P less than .07) for wethers fed SBM treatments than for wethers fed urea.(ABSTRACT TRUNCATED AT 250 WORDS)