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Simple Summary: There is rising interest globally in reducing the use of antibiotics in livestock feeding regimens. Phytogenic feed additives have been evaluated for their potential use to replace compounds such as ionophores in finishing cattle diets. The effects of saponin-containing extracts from Yucca schidigera (YSE) on ruminal fermentation, average daily gain, and feed efficiency appear to be similar to monensin; however, YSE is not approved for the control or prevention of coccidiosis in cattle. Therefore, the objectives of this study were to evaluate sources and levels of anti-coccidial compounds and saponins, individually or in combination, on in vitro and in vivo ruminal fermentation and CH4 production. In summary, the combination of decoquinate with YSE did not influence in vivo CH4 production but tended to increase ruminal propionate proportion. Monensin inclusion decreased in vitro CH4 production and the acetate:propionate. Increasing saponin inclusion increased the propionate proportion in vitro but was not accompanied by a reduction in CH4 production. Four experiments were conducted to evaluate sources of anti-coccidial compounds and phytogenic saponin extracts on in vitro and in vivo ruminal fermentation and CH4 production at multiple inclusion levels. In experiment 1, eight steers were fed either a finishing diet or a finishing diet supplemented with 0.5 mg/kg BW decoquinate (DCQ) and 3.33 mg/kg BW Yucca schidigera extract (YSE), and respiratory gas exchange was measured. In experiment 2, four ruminally-cannulated steers were fed the same treatments as experiment 1, and ruminal fermentation was evaluated. Anti-coccidial sources (experiment 3; monensin, DCQ, amprolium) and saponin sources (experiment 4; YSE, Quillaja saponaria extract) and levels were evaluated for effects on in vitro ruminal fermentation and CH4 production. DCQ + YSE supplementation did not influence (p ≥ 0.24) in vivo respiratory gas consumption/production, in situ DM degradation, or liquid passage kinetics. Ruminal propionate proportion tended to increase (p = 0.09) with DCQ + YSE. Monensin decreased (p ≤ 0.04) in vitro acetate:propionate and CH4 production; saponin supplementation linearly increased (p < 0.01) propionate proportion but did not influence (p ≥ 0.38) in vitro CH4 production. Saponins and non-antibiotic anti-coccidials did not influence in vitro or in vivo CH4 production with finishing diets. [ABSTRACT FROM AUTHOR]

A data set was used to determine how various factors affect the occurrence of dark-cutting beef and selected carcass traits in finished beef cattle. Data were collected in 1989 and 1990 from one packer with plants located in Amarillo, TX; Boise, ID; Dakota City, NE; and Garden City, KS. The data set consisted of 3,659 lots consisting of 724,639 cattle. Compared with those at Boise and Dakota City, cattle slaughtered in Amarillo and Garden City had a higher incidence of dark cutters (1.1 vs .3%; P < .01) and a lower quality grade (50 vs 64% Choice plus Prime; P < .01). The highest incidences of dark cutters occurred during August, September, and October (1.1 to 1.4%; P < .01), with incidences of .4 to .7% during the other months. Carcass quality grade was higher during January, February, and March compared with May through November (60 to 62% Choice plus Prime vs 52 to 58%; P < .01). As the number of cattle in a lot increased, the incidence of dark cutters increased from .4 to 1.2% (P < .01), and quality grade declined from 62 to 52% Choice plus Prime (P < .01). As the mean weight of cattle in the lot increased, the incidence of dark cutters declined from .94 to .6% (P < .01), and carcasses grading Choice plus Prime increased from 56 to 62% (P < .01). With cattle held over a weekend or holiday, ('carry cattle') the incidence of dark cutters increased from .8 to 1.6% (P < .01). We conclude that packing plant location, month of the year, weight of cattle, carry cattle, and number of cattle in a lot are most likely to influence the incidence of dark cutters and carcass quality traits. Key Words: Dark Cutting Meat, Stress, Beef Cattle, Carcasses

Experimental studies to identify conditions to introduce intestinal cellulolytic bacteria into bovine rumen and pig large intestine reveal that a competition should be overcome for efficient introduction of these organisms into an intestinal ecosystem. In bovine rumen Clostridium longisporum exists as a transient organism, while C. herbivorans is part of the pig large intestine.

Daily additions of 3 g of Amaferm to alfalfa (13% CP) and bromegrass (6% CP) diets were evaluated for effects on ruminal and postruminal fiber and organic matter digestion, fermentation profile, and duodenal bacterial nitrogen flow. Eight beef cows were fitted with ruminal and duodenal cannulas. Two experiments were conducted. Eight cows were fed bromegrass hay, four received Amaferm and four served as controls; later, seven cows received alfalfa hay with three receiving Amaferm and four serving as controls. Each experiment lasted 28 d: d 1 to 14 for adaptation, d 15 to 21 for measurement of feed intake, and d 22 to 28 for ruminal and duodenal sampling. Dacron bags containing NDF substrate from alfalfa or bromegrass were used to determine ruminal fiber degradation at 3, 6, 9, 12, 24, 48, and 72 h. There were no Amaferm effects (P [is greater than] .15) on rate or extent of fiber degradation in situ when bromegrass or alfalfa was fed. There were no Amaferm effects (P [is greater than] .10) on concentrations or molar proportions of ruminal VFA, pH, or [NH.sub.3] or on feed intake in either experiment. There were no effects (P [is greater than] .10) of Amaferm on site or extent of organic matter or fiber digestion, or duodenal nitrogen flow in cows fed either bromegrass or alfalfa. Amaferm increased (P [is less than] .10) the number of ruminal anaerobic bacteria in cows fed bromegrass but not in those fed alfalfa. Amaferm did not affect (P [is greater than] .10) the total number of cellulolytic bacteria in cows fed either diet; however, for cows that received bromegrass, Amaferm increased (P [is less than] .02) the proportion of Ruminococcus albus isolates from 21.7 to 33.3% of the total cellulolytics. Results indicate that Amaferm increased the number of total ruminal anaerobes when brome hay was fed; however, no affect on microbial protein synthesis or rate and extent of fiber degradation occurred.

Aspergillus oryzae fermentation extract (Amaferm) induces the breaking up of forage fiber by ruminal microorganisms in vitro, in a time-dependent manner. The rate of breaking up of switchgrass fiber fractions or brome grass by ruminal microorganisms is increased by Amaferm in either the liquid filtrate form or the dry form. The rise in degradation of brome grass neutral detergent fiber is not likely to be due to antibiotics.

The objective of this study was to evaluate in situ ruminal digestion characteristics of steam-flaked corn with large differences in starch availability (SA) using two different models: 1) increasing flake density and 2) exposure to 55°C temperatures to induce starch retrogradation. Five ruminally-cannulated steers (body weight = 390 ± 7.86 kg) were pen-fed a starter diet. In Exp. 1, sifted flakes with flake densities of 257, 296, 335, 373, and 412 g/L (SA: 87%, 76%, 66%, 43%, and 49%, respectively) were evaluated. In Exp. 2, three steam-flaked corn fractions were evaluated: flakes + fines (not sifted), sifted flakes (>4-mm), and sifted fines (< 4-mm). Feed fractions were stored for 3-d at either 23°C or 55°C (average SA across steam-flaked corn fractions: 53.3% and 25.5% respectively). Treatments of Exp. 2 were arranged with a 3 × 2 factorial. Both experiments were duplicated and analyzed as randomized complete block designs. In Exp. 1, the fractional rate of degradation linearly decreased (P < 0.001) and effective ruminal dry matter degradability (ERD) linearly decreased (P < 0.001) from 80.8% to 60.3% as flake density increased from 257 to 412 g/L. In Exp. 2, storage of steam-flaked corn samples at 55°C for 3-d decreased (P < 0.001) the fractional rate of degradation and ERD by 38.6% and 21.7% across all feed fractions, respectively. Using data from Exp. 1 and 2, SA of sifted flakes was positively correlated (Pearson = 0.8435; R2 = 0.71; P < 0.001) to ERD. The results of the current study demonstrate that decreased SA resulting from starch retrogradation or increased flake density is associated with decreased ERD. Decreases in SA and ERD may indicate that increasing flake density or starch retrogradation could potentially alter the site of digestion in cattle, by increasing postruminal starch flows. [ABSTRACT FROM AUTHOR]