Effects of live yeast (Saccharomyces cerevisiae) in steam-flaked corn-based diets fed to natural-program beef cattle on growth performance, total tract apparent digestibility, carcass characteristics, and feeding behavior were evaluated in a randomized block design experiment. Steers (n = 144; 341 ± 7.03 kg) were blocked by initial BW and assigned randomly to 1 of 3 treatments (n = 12 pens/treatment with 4 steers/pen). Treatments included: a) Control (CTL; no yeast); b) low yeast (LY; 1.5 g/animal daily [3 x 10¹⁰ CFU]); and c) high yeast (HY; 3.0 g/animal daily [6 x 10¹⁰ CFU]). Technologies such as implants, ionophores, and antibiotics were not used, and the steam-flaked corn-based finishing diets were fed to provide ad libitum access to feed. Yeast was included in a cottonseed meal-based premix as 1% of the dietary DM. Spot fecal samples (twice daily for 5 consecutive days) and diets were composited by pen and analyzed for acid insoluble ash to estimate apparent total tract digestibility of nutrients. Cattle were slaughtered on d 183 (4 blocks) and 204 (8 blocks). Dry matter intake (P ≥ 0.29), ADG (P ≥ 0.17), and G:F (P ≥ 0.33) did not differ among treatments. The percentage of premium Choice (P < 0.01) carcasses increased linearly with increasing yeast inclusion in the diet. A quadratic response was observed for total tract apparent digestibility, in which steers fed LY had greater digestibility (P < 0.01) of DM by 5.4%, OM by 4.8%, NDF by 15.2%, ADF by 20.2%, CP by 6.2%, and ether extract by 2.5% compared with steers fed CTL. Feeding behavior was not affected (P = 0.28) by treatments. Live yeast improved digestibility of DM, OM, CP, EE, and fiber, without changing feeding behavior and growth performance of natural-program steers fed steam-flaked corn-based finishing diets.

Effects of a tannic acid blend (ByPro; Silvateam USA, Ontario, CA) added to steam-flaked corn–based fishing diets on beef cattle growth performance, carcass characteristics, nutrient digestibility, fecal N volatilization, and meat lipid oxidation were evaluated. Steers (n = 144; 349 ± 25 kg initial BW) were blocked by initial BW and assigned randomly to 1 of 3 treatments with 12 pens/treatment and 4 steers/pen and fed ad libitum. Treatments included a control (CON; no ByPro) and ByPro fed at 30 or 60 g DM/steer daily (30-ByPro and 60-ByPro, respectively). Pen fecal samples were collected 7 d after cattle were shipped to slaughter for estimation of N volatilization. Strip loins were aged for 21 d for evaluation of color and antioxidant activity. Intake quadratically increased (P = 0.05) from d 0 to 35, whereas linear trends were observed for increased DMI from d 0 to 105 and d 0 to slaughter (P = 0.07 and P = 0.06, respectively), resulting in a 3.7% greater overall DMI for 60-ByPro than for CON. No differences were detected for carcass-adjusted ADG (P = 0.65) or G:F (P = 0.17). Carcass characteristics including HCW (P = 0.52), fat thickness (P = 0.32), LM area (P = 0.57), quality grade (P = 0.44), yield grade (P = 0.29), and percentage of condemned livers (P = 0.13) were not affected by treatments. Apparent total tract digestibility of starch linearly decreased tendency (P = 0.03) with increasing ByPro dose, whereas tends for a linear decrease (P = 0.09) in CP and a quadratic increase (P = 0.09) in OM digestibility were observed. No effects of treatment (P ≥ 0.39) were noted for fecal N volatilization. An increase (P < 0.01) in metmyoglobin in strip loin steaks was observed with ByPro inclusion. Oxymyoglobin decreased (P < 0.01) as display day progressed, except on d 5, at which time CON and 30-ByPro steaks had lower proportions than 60-ByPro steaks. Only subtle changes in discoloration ratio and deoxymyoglobin were observed, whereas no effects (P ≥ 0.43) for pH or thiobarbituric acid reactive substances were noted. Feeding ByPro increased DMI during the first half of the feeding period without negatively affecting gain efficiency; however, fecal N retention was not altered by ByPro. ByPro did not negatively affect meat quality or carcass characteristics, and it did not seem to affect retail meat antioxidant activity.

The effects of dietary pretreatment with fibrolytic enzyme-based cocktail were evaluated in 2 studies: (1) in vitro true digestibility; and (2) intake, digestibility, feeding behavior, and ruminal fermentation of beef steers fed growing diets. For the in vitro assessment, the ruminal inoculum was collected from 2 steers (BW = 543 ± 45 kg; 4-h after feeding; growing diets) and enzymes included or not (Trichoderma reesei fermentation extract; 0.75 µL/g of substrate DM). Within in vitro batches (n = 4), 12 substrates were incubated and in vitro true nutrient digestibility was evaluated. For study 2, 5 ruminally cannulated beef steers (BW = 520 ± 30 kg) were used in a 5 × 4 unbalanced Latin square using a 2 × 2 factorial arrangement of treatments: (a) diet quality (high = HQ; and low = LQ) and (b) enzyme inclusion (0 or 0.75 mL/kg of diet DM). Steers were fed ad libitum during four 21-d periods consisting of 14-d of adaptation and 7-d of collections. An enzyme × substrate was observed (P < 0.01), in which DM, OM, and NDF disappearance of sorghum grain increased with enzymes addition. Addition of enzymes increased (P < 0.01) ADF digestibility for all substrates. No diet quality × enzyme (P ≥ 0.18) was observed for intake variables in study 2. Enzyme-fed steers increased (P ≤ 0.05) intake of DM, digestible DM, NDF, and ADF compared with steers not fed fibrolytic enzymes. Addition of enzyme did not affect (P ≥ 0.28) apparent total tract digestibility of beef steers. Steers fed HQ diets consumed more (P ≤ 0.04) DM, digestible DM and OM, and less (P ≤ 0.03) total and digestible fiber than steers fed LQ diets. Ruminal pH average decreased (P = 0.01) for steers fed HQ or enzyme-fed diets compared with other treatments. A tendency (P = 0.06) toward improved total VFA was observed on enzyme-fed steers with HQ diets, but not for LQ diets. The molar proportion of ruminal propionate increased (P = 0.01) when steers were fed enzyme. Steers fed HQ diets had greater (P < 0.01) propionate and valerate molar proportions, lower (P < 0.01) acetate and acetate:propionate ratio than steers fed LQ diets. In vitro methane and total gas production were not affected (P ≥ 0.50) by dietary treatments. Fibrolytic enzymes positively affected digestion of multiple roughage sources commonly fed to cattle and might have additional benefit when used on unprocessed sorghum grain. Fibrolytic enzymes in beef cattle growing diets stimulated intake and generated positive impacts on ruminal fermentation.

Alfalfa (Medicago sativa L.) can enhance the supply of nutritious forage when interseeded into semiarid native grassland. Alfalfa is a high water‐using species; therefore, a possible trade‐off between soil water depletion and nutritive value merits study. We determined the effects of interseeding three alfalfa cultivars at two densities on crude protein (CP) and digestible organic matter (DOM) accumulations, the water footprint (WF, m³ evapotranspiration kg⁻¹) of CP and DOM accumulation at two row spacings, and the marginal cost (MC) of such trade‐offs. Nutritive values and accumulation of CP and DOM for mixtures with alfalfa planted at 36‐ or 71‐cm row spacing did not differ in 2018 (P > .05), as both spacings reduced the WF over grass only (P < .0001). Alfalfa presence reduced the WF (P < .001) with respect to CP and DOM accumulation from 20.17 and 3.07 m³ kg⁻¹ in the grass‐only control to 10.14 and 2.22 m³ kg⁻¹ in alfalfa–grass mixtures, respectively. Interseeding alfalfa in wide rows had 23 and 26% less MC of revenue increment than interseeding in narrow rows, relative to grass only in Years 2 and 3, respectively (P < .01). Hay‐type cultivars NuMex Bill Melton and WL 440HQ enhanced the forage mixture nutritive value more than the grazing‐type Falcata–Rhizoma blend, mainly driven by greater alfalfa growth. Interseeding alfalfa into native grasses in wide rows can increase the efficiency of water use (lower WF) by enhancing forage nutritive value at low MC, thereby inducing a minimal trade‐off in soil water consumption.

Crossbred beef steers fitted with a ruminal cannula were used to study the effects of silage type (BH 8895 corn or AF7401 sorghum) and level of inclusion (10 or 20%) in beef cattle finishing diets on digestibility of nutrients, ruminal kinetics, in vitro methane production, and feeding behavior. A 4 × 6 unbalanced Latin square design was used (6 steers; 363 ± 23 kg; 4 diets: corn silage [CS] or sorghum silage [SS], both at 10 or 20% inclusion, DM basis). Each period consisted of 14 d of adaptation and 7 d of collection. Steers were fed once daily at 1000 h. An additional study evaluated the ruminal degradability of intact ensiled sorghum grain ruminally incubated in 3 steers (547 ± 56 kg BW), using the same hybrids from the main study from 10 laboratory experimental silos. The GLIMMIX procedures of SAS were used for statistical analyses. Steers fed SS had greater NDF intake (P < 0.01) compared with the ones fed CS. The magnitude of the NDF intake change depended on the level of inclusion (P < 0.01), which was 6 and 16% for 10 and 20% inclusion, respectively. Regardless the level of inclusion, CS diets promoted greater (P ≤ 0.01) apparent total tract digestibility of nutrients evaluated (DM, OM, NDF, ADF, hemicellulose, and starch) compared with SS diets. Steers fed SS diets tended to chew 1.1 h/d more (P = 0.07) than steers fed CS diets. The level of inclusion increased (P = 0.02) the chewing time per day by 1.3 h. No major differences were observed in any of the ruminal pH and in vitro gas production variables evaluated for silage type and inclusion level (P ≥ 0.09). The CS-fed steers had 12% greater total VFA concentration and an 18.5% lower (P < 0.01) acetate-to-propionate ratio compared with SS-fed steers. The acetate-to-propionate ratio was 16% greater (P < 0.01) when steers were fed SS compared with when steers were fed CS. The CS samples were more extensively ruminally degraded (P < 0.01) than the SS samples. Greater (P < 0.01) NDF ruminal disappearance was observed in ruminal environments containing 20% silage compared with those containing 10% silage. After 96 h inside the rumen, intact ensiled sorghum grain degradability of DM reached only 51.7%. Replacing CS with SS in beef finishing diets (low roughage inclusion) requires adjustments to balance dietary energy. Sorghum material induced a desirable roughage effect in feeding behavior but also offered the potential for improved regarding fiber digestibility and intact grain ruminal degradability. Copyright © 2017. American Society of Animal Science .

The effects of the dietary inclusion of a mixture of bacterial direct-fed microbial (DFM) on feedlot beef cattle growth performance, carcass characteristics, nutrient digestibility, feeding behavior, and ruminal papillae morphology were evaluated. Crossbred-Angus steers (n = 192; initial BW = 409 kg ± 8 kg) were blocked by BW and randomly assigned into 48 pens (4 steers/pen; 16 pens/treatment) following a randomized complete block design. A steam-flaked corn-based fishing diet was offered to ad libitum intake once daily for 153 d containing the following treatments: 1) Control (no DFM, lactose carrier only); 2) Treat-A (Lactobacillus animalis, Propionibacterium freudenreichii; Bacillus subtilis; and Bacillus licheniformis), at 1:1:1:3 ratio, respectively; totaling 6 × 10⁹ CFU (50 mg)/animal-daily minimum; and 3) Treat-B, the same DFM combination, but with doses at 1:1:3:1 ratio. Bacterial counts were approximately 30% greater than the minimum expected. Data were analyzed using the GLIMMIX procedure of SAS, with pen as the experimental unit, the fixed effect of treatment and the random effect of BW-block, while pre-planned contrasts comparing Control × treat-A or treat-B were used. Steers offered treat-A had increased carcass-adjusted ADG (P = 0.03) by 6.7%, gain efficiency (P < 0.01) by 6%, tended (P = 0.07) to have increased carcass-adjusted final BW by 15 kg, and hot carcass weight (P = 0.07) by 10 kg, while treat-B did not differ (P ≥ 0.17) from control. Overall DM intake (P = 0.36) and other carcass traits (P ≥ 0.13) were not affected by treatments. Steers offered treat-A tended to have increased digestibility of DM (P = 0.07) by 3%, NDF (P = 0.10), and hemicellulose (P = 0.08) by 9% compared with control, while treat-B did not differ (P ≥ 0.10) from control. No treatment × period interactions (P ≥ 0.21) or main effects of treatment (P ≥ 0.12) were observed during 24-h feeding behavior. Steers ruminated, ate, chewed, and were more active (P ≤ 0.01) during the second behavioral assessment (d 113), while drinking behavior was not affected (P ≥ 0.88). Ruminal papillae morphology and ruminal ammonia concentration (ruminal fluid collected at slaughter facility) were not affected by treatment (P ≥ 0.39). Steers offered the DFM treat-A had improved growth performance and it positively affected carcass weight and nutrient digestion. The DFM combinations did not seem to affect feedlot cattle feeding behavior or ruminal papillae morphology.