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A study involving a 2 x 2 x 2 factorial arrangement of treatments was conducted to evaluate effects of hybrid (Pioneer 3335 and 3489), maturity (half milkline and blacklayer), and mechanical processing (field chopper with and without on-board rollers engaged) on intake and digestibility of corn silage. Forty Angus steers (322 +/- 5.2 kg BW) were assigned to the eight silage treatments (five steers per treatment) and individually fed using electronic gates. Diets consisted of 60% corn silage and 40% chopped alfalfa hay (DM basis). Following a 5-d adaptation period, intake was measured for 7 d and subsequently fecal samples were collected for 5 d. Chromic oxide (5 g/d) was fed beginning 7 d before fecal sample collection and digestibility was determined by the ratio of Cr in the feed and feces. Steers were reallocated to treatments and these procedures were repeated, providing 10 observations per treatment. In addition, all silages were ruminally incubated in six mature cows for 0, 8, 16, 24, 48, and 96 h to determine extent and rate of DM, starch, NDF, and ADF disappearance. Processing increased DMI of hybrid 3489 but did not affect DMI of hybrid 3335 (hybrid x processing; P < 0.06). Total tract digestibility of DM, starch, NDF, and ADF decreased (P < 0.01) as plant maturity increased. Maturity tended to decrease starch digestibility more for hybrid 3489 than for hybrid 3335 (hybrid x maturity; P < 0.10). Processing increased (P < 0.01) starch digestibility but decreased (P < 0.01) NDF and ADF digestibility, resulting in no processing effect on DM digestibility. There was a numerical trend for processing to increase starch digestibility more for latethan for early-maturity corn silage (maturity x processing; P = 0.11). Processing increased in situ rates of DM and starch disappearance and maturity decreased in situ disappearance rates of starch and fiber. These data indicate that hybrid, maturity, and processing all affect corn silage digestibility. Mechanical processing of corn silage increased starch digestibility, which may have been associated with the observed decreased fiber digestibility.

To assess the effects of feeding high-oil corn on carcass characteristics and meat quality, 60 yearling steers were fed high concentrate diets containing either control corn (82% of diet), high-oil corn (82% of diet), or high-oil corn at a concentration that was isocaloric with the control diet (74% of diet). After being fed for 84 d, steers were slaughtered. At 72 h postmortem, carcass data were collected and rib sections from five steers grading U.S. Choice and five steers grading U.S. Select from each treatment were collected, vacuum packaged, and aged for 14 d. Three steaks (2.54 cm thick) were removed from each rib for Warner-Bratzler shear force measurement, sensory appraisal, and fatty acid composition analyses. Data were analyzed with treatment as the main effect for the carcass data and treatment, quality grade, and two-way interaction in the model for the longissimus data. The two-way interaction was nonsignificant (P > 0.05) for all variables tested. No differences were detected (P > 0.05) in carcass measurements except for marbling scores and quality grades, both of which were greater (P < 0.05) for carcasses from steers fed the high-oil corn. Overall, 78% of steers fed the high-oil corn graded U.S. Choice compared with 47% for the control and 67% for isocaloric group. Shear force and sensory properties of the longissimus were not different (P > 0.05) among treatments. Steaks from U.S. Choice carcasses rated higher (P < 0.05) for tenderness and tended to rate higher (P < 0.10) for juiciness. Feeding the isocaloric and high-oil diets increased (P < 0.05) linoleic acid, arachidonic acid, and the total PUFA content of lipid extracted from the longissimus. Saturated fatty acid percentage was lowest (P < 0.05) for high-oil corn and highest (P < 0.05) for control, with isocaloric being intermediate. Feeding high-oil corn increased (P < 0.05) pentadecyclic acid, margaric acid, and total odd-chain fatty acid content. Feeding high-oil corn in finishing beef cattle diets enhanced intramuscular lipid deposition and increased unsaturation of fatty acids of the longissimus.

In trial 1, 30 midlactation (213 d in milk) Holstein cows were randomly assigned to a control or enzyme treatment in a two-period crossover design and were fed a total mixed ration based on alfalfa hay and silage. Cows on the enzyme treatment received an enzyme solution containing cellulases and xylanases, which was sprayed on the forage component of the ration at a rate of 1.65 ml/kg of forage dry matter (DM) between 8 and 24 h prior to feeding. Cows consuming the forage treated with enzyme produced more milk (27.2 vs. 25.9 kg/d) and digested more DM per day than did cows fed the control forage. In trial 2, 40 early lactation Holstein cows were assigned to one of four treatments for 16 wk. Following a 2-wk covariate period, cows were assigned to 1) no enzyme treatment, 2) a low (1.25 ml/kg of forage DM) enzyme treatment, 3) a medium (2.5 ml/kg of forage DM) enzyme treatment, or 4) a high (5.0 ml/kg of forage DM) enzyme treatment. Enzymes were a 2:1 combination of cellulase and xylanase diluted in water and sprayed on a combination of alfalfa hay and silage and whole cottonseed immediately before mixing with a concentrate based on barley. Dry matter intakes were similar for cows on treatments 2, 3, and 4 and were greater than those for cows on treatment 1. Production of milk, 3.5% fat-corrected milk, and energy-corrected milk was greater for cows on treatment 3 than for cows on treatment 1. Fibrolytic enzymes applied to the forage portion of the rations prior to feeding improved lactational performance of early and midlactation cows.

We conducted two feedlot trials and one metabolism trial to evaluate the effect of barley level, barley bulk density, and physical form of roughage on lamb growth performance and digesta kinetics. Level of whole barley (50, 70, 90%) and type of roughage (chopped or pelleted alfalfa) were evaluated in Trial 1 (50 d period). Trial 2 (50 d) evaluated barley bulk density (heavy = 671 and light = 607 kg/m3), form of roughage (pelleted or chopped alfalfa), and level of barley (80 or 40%). The influence of treatments used in Trial 2 on digesta kinetics was evaluated in Trial 3. Gain:feed increased and DMI decreased (P < .10) linearly with increasing level of barley, and ADG and DMI were greater (P < . 10) for lambs fed pelleted vs chopped alfalfa in Trial 1. The 70% barley diet produced the highest yield grade and kidney-pelvic fat and the lowest leg score among barley levels (P < .10). Lambs fed pelleted alfalfa had heavier carcasses and a thicker body wall than lambs fed chopped alfalfa (P < .02). In Trial 2, DMI was less and gain:feed greater (P < .01) for lambs fed the heavy barley than for lambs fed the light barley and for the 80% barley diet compared to the 40% barley diet. Lambs fed pelleted alfalfa had greater dressing percentages than lambs fed chopped alfalfa. Backfat and body wall thickness were greater (P < .10) for lambs fed the 80% barley diet than for those fed the 40% barley diet. In Trial 3, retention time of barley was greater (P < .10) for lambs fed light rather than heavy barley, and retention time of alfalfa was greater (P < .10) for lambs fed chopped compared with pelleted alfalfa. Acetate:propionate ratio was greater (P < .10) for lambs fed light vs heavy barley and lambs fed the 40 vs 80% barley diets. Ruminal pH was lower (P = .05) and in situ barley digestion greater (P = .03) over time in lambs fed the 80% barley diet than in lambs fed the 40% barley diet. Feedlot lamb ADG was not always greatest with high levels of barley; however, gain:feed improved at the higher barley levels. The higher barley levels seemed to result in fatter lambs.

A study was conducted to examine the method of delivery of a solution containing cellulases and xylanases on the digestion of a forage-based diet. Five ruminally cannulated beef steers (536 kg BW) were randomly assigned to a control (CON) or one of four enzyme treatments in a 5 x 5 Latin square experiment. Steers were fed a 70:30 (DM basis) grass hay:barley diet. Enzyme-treated rations contained a solution of fibrolytic enzymes at the rate of 1.65 mL/kg of forage DM. Enzyme application treatments were 1) enzyme to forage 24 h before feeding (F-24), 2) enzyme to forage 0 h before feeding (F-0), 3) enzyme to barley 0 h before feeding (B-0), and 4) enzyme infused ruminally 2 h after feeding (RI). Dry matter and NDF intakes were not different (P > .10) across treatments. Ruminal pH was lower and total VFA concentration at 16 h after-feeding was greater (P < .10) for steers fed enzyme treatments compared with CON. Rate of NDF disappearance was greater (P < .05) for enzyme-treated than for untreated grass substrate. Ruminal infusion of enzymes compared with F-24 and F-0 produced lower disappearance of DM at 8 and 32 h (P < .10), NDF at 32 h (P < .10), and DM and NDF at 96 h (P < .05). Rate of DM disappearance of enzyme-treated grass hay was greater (P < .10) for steers fed B-0 than for those fed F-24 and F-0 and for CON than for F-24 and F-0. Total tract digestibility of DM, NDF, and ADF was greater (P < .10) for F-24 and F-0 than for CON. Forage transit time was shorter (P < .10) for B-0 than for F-24 and F-0; however, all other contrasts for particulate passage did not differ (P > .10). Results from this study indicate that direct application of enzymes to forages is capable of improving forage digestion.

In situ and in vitro studies with a 3 x 2 x 5 factorial arrangement of treatments with an added untreated control evaluated three enzyme preparations, two levels of enzyme, and five moisture conditions of grass forage. Enzyme preparations predominantly contained cellulase and xylanase and will be designated as enzyme 1 (E1), enzyme 2 (E2), and a 50:50 combination of E1 and E2 (E1E2). The five moisture conditions included fresh, wilted, dried and rehydrated to fresh, dried and rehydrated to wilt, and dried grass. Addition of the high level of E1E2 to dried grass improved (P < .05) in vitro DM (43.5 vs 38.7%) and NDF (31.1 vs 26.0%) disappearance (48 h incubation) compared with the control treatment. Also, IVDMD was greater (P < .05) for the low level of E1 applied to wilted grass compared with the control. No other enzyme application improved in situ or in vitro disappearance of substrate over the control. In vivo responses of enzyme treatments found most likely to be effective from degradability studies were measured using four ruminally cannulated steers in a 4 x 4 Latin square experiment. Treatments examined were E1 applied to fresh forage, then dried; E1 applied to wilted forage, then dried; E1E2 applied to dry forage immediately before feeding (E-dry), and untreated forage (control). All forage treatments were harvested as dry hay. Total diet and hay DM intakes were greater (P < .05) for the E-dry than for the control diet. Rate of in situ NDF disappearance and total tract DM and NDF digestibility were greater (P < .05) for the E-dry than for the other treatments. Ruminal fluid ammonia N concentration, total VFA concentration, and pH were not altered (P > .10) by dietary treatment. Ruminal particulate passage rate was greater (P < .05) and ruminal retention time was shorter (P < .05) for the E-dry than for the control treatment. Data from this study suggest that addition of fibrolytic enzymes to grass hay before feeding has the potential to enhance intake and digestion.

Five ruminally and duodenally cannulated steers were used in a 5 x 5 Latin square design with a 2 x 2 + 1 arrangement of treatments to study the effects of barley variety and dietary barley content on digestive function in steers fed grass hay-based diets. Barley varities evaluated were Russell and Steptoe, which had bulk densities of 67.7 and 64.5 kg/hL, respectively. Supplemental treatments were as follows: corn, low Russell (Ru-lo), low Steptoe (St-lo), high Russell (Ru-hi), and high Steptoe (St-hi). Corn, Ru-lo, and St-lo were provided at 30% (DM basis) of grass hay-based diets, whereas Ru-hi and St-hi were provided at 35.5% of diet DM (equal starch content as the corn treatment). No treatment differences (P > .10) were observed for DMI, ruminal particulate passage rate, and NDF total tract digestibility. Ruminal DM and starch digestibility were greater (P < .01) for barley-containing diets than for the corn diet. Similarly, total tract DM (P < .10) and starch (P < .01) digestibility was greater for barley than for corn diets. Microbial protein and non-NH3 N flow to the small intestine were greater (P < .01) for the barley diets than for the corn diet. Starch intake (P < .01) and DM digestibility (P < .10) were greater for high- than for low-barley diets; however, differences due to barley variety were not observed (P > .10). In situ disappearance of grass hay NDF at 8 and 96 h of incubation was greater (P < .05) for barley than for corn diets. Rate of in situ disappearance of grain DM was greater (P < .01) for barley than for corn and for Russell than for Steptoe barley. Responses suggest that ruminal and total tract digestibility and protein flow to the small intestine can be increased with barley compared with corn as an energy supplement to grass hay-based diets.