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The inclusion of Aspergillus oryzae prebiotic (AOP; Amaferm, Biozyme Inc., St Joseph, MO) in ruminant diets has been proven to stimulate cellulolytic ruminal microorganisms, although, its positive effect on nutrient digestibility seems to be diet dependent. Our objective was to evaluate how AOP influences the apparent total tract digestibility of dry matter (DM) and neutral detergent fiber (NDF) at varying levels of intake, for diets with different forage sources and inclusion levels. Data were compiled from 3 experiments containing 4 diets for backgrounding cattle, assessing the use of AOP as a feed additive. The studies were Exp. 1): corn silage-based diet (CS; n = 24 steers), Exp. 2-A): sorghum silage-based diet (SS; n = 20 heifers), Exp. 2-B): citrus pulp and cotton gin byproducts-based diet (BP; n = 20 heifers), and Exp. 3): bermudagrass hay-based diet (BH; n = 24 steers). Separate ANCOVA analyses by diet were conducted using SAS, including in the model the effect of treatment (TRT; AOP vs. No AOP) and the interaction between TRT and level of intake (dry matter intake; DMI). Level of intake was calculated as percentage of body weight (DMI/BW). Least square mean differences between treatments were conducted at different levels of intake at which both treatments were represented. For apparent total tract digestibility of DM and NDF (NDFD), the TRT × DMI/BW interaction was significant (P ≤ 0.05) in the case of the CS and SS diets, but not in the BP and BH diets (P ≥ 0.10). For both silage diets, NDF and DM digestibility decreased as the level of intake increased. Consequently, the positive effect of AOP on NDFD was greater at increased levels of intake (3.3 and 3.5% of the BW for CS and SS, respectively), resulting in 9.8% improvement on NDFD for the CS diet (P = 0.04, 37.9 vs. 41.6% for No AOP vs. AOP, respectively) and 25% improvement in the SS diet (P = 0.01, 42.5 vs. 53.2% for No AOP vs. AOP, respectively). At a moderate intake (2.5% of the BW), AOP improved NDFD by 6.0 and 14.1% for the CS and SS diets, respectively (P ≤ 0.05). While at reduced intake (1.8 and 1.7% of BW, for CS and SS), NDFD did not differ (P ≥ 0.10) between treatments for either CS (47.9%) or SS (56.5%) diets. In conclusion, the inclusion of AOP in silagebased diets attenuates the decline on apparent total tract digestibility of NDF associated with increased feed intake, helping to maintain digestibility closer to its maximum potential. Whereas, at reduced levels of intake, it is more unlikely to observe a positive effect of AOP on fiber digestibility. [ABSTRACT FROM AUTHOR]

Eighty-four Angus crossbred heifers (13 ± 1 mo of age, 329.5 ± 61.92 kg of body weight [BW]) were used in a generalized randomized block design with a 2 × 2 factorial arrangement of treatments. The factors evaluated were: 1) diet type (whole plant sorghum silage [ SS ] vs. byproducts-based [ BP ]), and 2) feed additive: Aspergillus oryzae prebiotic (AOP; 2 g/d) vs. Negative control (CTL; 0 g/d), resulting in four treatments: sorghum silage-control (SC), sorghum silage-AOP (SA), byproducts-control (BC), and byproducts-AOP (BA). Heifers were stratified by body weight (BW), randomly assigned to treatments (21 heifers per treatment) and housed in 12 pens equipped with two GrowSafe feed bunks each to measure individual dry matter intake (DMI). After a 14-d adaptation, BW was measured every 14 d for 56 d. Chewing activity was monitored through collar-mounted HR-Tags (heat-related tags). Following the performance period, apparent total tract digestibility was measured in 40 heifers, using indigestible neutral detergent fiber as a marker. Heifers fed with the BP diets had greater DMI (2.92% vs. 2.59% of BW, P < 0.01) and average daily gain (ADG ; 1.16 vs. 0.68 kg, P ≤ 0.01) than heifers fed with SS diets. Compared with BP-fed animals, heifers consuming the SS diets had 23 more visits/d to the feed bunks (P ≤ 0.01), consumed 53% less dry matter on each visit (P ≤ 0.01), and spent 39% more min chewing/d and 63% more min chewing/kg of DMI (P ≤ 0.01). However, chewing measured in min/kg of neutral detergent fiber intake was not affected by treatment (average 111.3 min/kg of NDF intake). Feeding AOP improved gain:feed (GF) by 15% in BP-fed heifers (0.120 vs. 0.104 kg/kg; P < 0.05). Inclusion of AOP increased organic matter digestibility (OMD) in SS diets (55.88% vs. 49.83%; P < 0.01), whereas it decreased OMD in BP diets (61.67% vs. 65.77%; P < 0.05). In conclusion, ADG and GF of BP-fed heifers was greater than SS-fed heifers, and GF was greater with AOP supplementation in BP-fed heifers. Improvement in GF in BP-fed heifers was likely not related to differences in nutrient digestibility as AOP inclusion did not enhance digestibility in the BP diet. Additionally, the effects of the AOP inclusion appear to be diet-dependent, where the 15% improvement in GF by AOP occurred in heifers fed with the more fermentable diet. Therefore, further research should explore the mechanisms responsible for the observed improvements in growth performance when feeding AOP to BP-fed heifers. [ABSTRACT FROM AUTHOR]

The value of carinata, a non-food oilseed crop, has been demonstrated as a high-quality jet fuel alternative and successful cover crop in the southeastern U.S.; however, research is limited regarding carinata as an alternative for commonly used protein sources in livestock. Eighty-four Angus crossbred heifers were used in a generalized randomized block design to evaluate the effects of supplementing carinata meal compared with cottonseed meal on performance, intake, and digestibility in a backgrounding corn silagebased diet. Treatments included: corn silage only (CS), corn silage + Brassica carinata meal (BCM) at 10% (BCM10) or 20 % (BCM20) inclusion, or corn silage + cottonseed meal at 10% inclusion (CSM). Protein sources were mixed with corn silage prior to delivery and provided ad libitum, with individual intake measured using the GrowSafe system. Data were analyzed using Proc Glimmix of SAS. An effect of treatment was observed (P < 0.01) for final body weight (BW), average daily gain, and gain to feed ratio, where CS was least. Dry matter intake (DMI; kg/d) was greatest (P = 0.01) for BCM10 compared with CS, yet BCM20 and CSM did not differ from CS or BCM10. No effect of treatment was observed on DMI as a percentage of BW (P = 0.35) or residual feed intake (P = 0.94). Heifers receiving CSM had the greatest (P < 0.01) intake of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF). Intake of crude protein (CP; P < 0.01) was least for CS and greatest for BCM20 and CSM, with BCM10 intermediate. Digestibility of all nutrients was least (P < 0.01) for CS, and greatest (P < 0.01) for BCM20 in CP and NDF, only, where BCM10 and CSM did not differ. Digestibility of DM, OM, and ADF was less (P < 0.01) in BCM10, greater in BCM20, while CSM did not differ between BCM10 and BCM20. Carinata supplemented at 10% diet DM performed similarly to cottonseed meal in backgrounding beef heifers fed a corn silage-based diet, thereby enhancing its value in the southeastern U.S. [ABSTRACT FROM AUTHOR]

Direct-fed microbials have been used in an effort to improve livestock production efficiency and reduce environmental impact. Among other species, spore forming bacteria such as Bacillus spp. present handling and processing advantages to be used as a probiotic. Several studies have demonstrated positive effects of Bacillus spp. on dairy cattle production. However, there is lack of information about its effects on beef cattle. Thus, the objective of this study was to evaluate the effect of a probiotic composed by a mixture of B. subtilis and B. licheniformis on beef cattle performance, nutrient utilization, and enteric methane emissions (CH4). For this purpose, a total of 108 Angus crossbred heifers (318 ± 40.4 kg of BW) were used in a generalized randomized block design. The heifers were fed a sorghum silage-based diet containing 1 of the 2 following treatments: 1) control (CTL, no additive), or 2) Bacillus spp. probiotic (BSL, 310 mg/kg of diet DM), in an attempt to provide an average of 3 g·animal-1·d-1. The experimental period consisted in 7 d of adaptation to the pens, followed by 77 d of performance data collection, 5 d of apparent total tract digestibility measurements, and 5 d of CH4 measurements. No effect of treatment (P > 0.05) was observed for dry matter intake, average daily gain, or gain-tofeed ratio. The inclusion of the probiotic did not affect (P > 0.05) apparent total tract digestibility of dry matter, organic matter, neutral detergent fiber and crude protein, whereas starch digestibility decreased (P = 0.027) with the probiotic inclusion. No differences (P > 0.05) were observed for CH4 between the two treatments. Accordingly, feeding Bacillus spp. did not affect cattle performance, nutrient utilization, or enteric CH4 emissions in beef heifers when included at 310 mg/kg of dietary dry matter. [ABSTRACT FROM AUTHOR]

This study investigated the effects of feeding an avian-derived polyclonal antibody preparation (PAP; CAMAS, Inc.) against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides (40, 35, and 25% of the preparation, respectively) on plasmatic haptoglobin and glucose concentrations (Exp. 1), and apparent total tract digestibility (Exp. 2) of beef cattle consuming a backgrounding diet. In Exp. 1, Angus crossbreed heifers and steers (n = 90; 373 ± 62 kg BW) were randomly assigned to receive a common ad libitum diet (76% TDN, 15.9% CP, DM basis) with the addition of 1 (PAP1), 3 (PAP3), or 0 g (CON) of PAP daily. Plasmatic concentrations of glucose and haptoglobin were measured on d 0, 14, 28, 42, and 56. In Exp. 2, 25 Angus crossbreed steers (390 ± 65 kg BW) were used in a completely randomized design. Steers were housed in 3 pens to receive the same diet and treatments from Exp. 1. Feed intake was measured using GrowSafe feed bunks, and indigestible neutral detergent fiber was used as the internal marker. In Exp. 1, a day effect was detected for plasmatic haptoglobin and glucose concentrations (P ≤ 0.04). In Exp. 2, no difference in DMI was observed (P = 0.88). Dry matter, organic matter, and acid detergent fiber digestibility in the total tract were reduced (P ≤ 0.05), whereas CP digestibility tended to decrease (P ≤ 0.07) in steers receiving PAP3 vs. CON and PAP1. Apparent total tract starch digestibility was increased (P ≤ 0.02) for PAP1 vs. PAP3. Neutral detergent fiber digestibility was greater (P < 0.01) for PAP1 vs. CON and PAP3. Feeding 1 g/d of a PAP against Streptococcus bovis, Fusobacterium necrophorum, and lipopolysaccharides increased fiber digestibility in backgrounding diets; however, further research is needed to understand the impaired responses on nutrient digestibility when greater doses are provided. [ABSTRACT FROM AUTHOR]