Two experiments were conducted to evaluate performance and forage utilization characteristics of beef cattle fed ammoniated wheat straw (AWS) unsupplemented except for minerals or supplemented with energy and protein. In Exp. 1, 194 crossbred beef cows (BW = 472 kg) in late gestation were allotted by weight, breed type, and age during two consecutive winters to 12 drylot pens (three pens/treatment) for a 60-d feeding trial. The AWS (3% NH3 wt/wt) was tubground through a 7.6-cm screen, and cows were allowed ad libitum access to the AWS. In Exp. 2, 16 ruminally fistulated Angus x Hereford steers (BW = 300 kg) were blocked by weight and randomized to treatments in a 35-d intake-digestion trial. Daily supplementation treatments in both experiments were Control, no supplemental energy or protein; LSG, 1.36 kg of sorghum grain (SG); HSG, 2.72 kg of SG; and SG + SBM, 1.02 kg of SG + .34 kg of soybean meal (SBM). All animals received .23 kg of mineral mixture formulated to meet a pregnant cow's mineral requirements. Supplements LSG and SG + SBM were fed to provide the same daily ME, and HSG and SG + SBM were fed to provide the same daily CP. Cows were managed as one group during and after calving. In Exp. 1, all supplements increased gain (P less than .01) vs Control, and cows fed SG + SBM had higher (P = .05) gains than those fed LSG. The SG + SBM supplement increased (P less than .01) change in cow body condition score compared with LSG.(ABSTRACT TRUNCATED AT 250 WORDS)

Six ruminally fistulated steers (550 kg) and 24 heifers (315 kg) were used to determine the effect of source and amount of ruminal-escape lipid in a supplement on forage intake and digestion. Steers were used in a 6 x 6 Latin square digestion study to evaluate six supplementation treatments: 1) negative control (NC), no supplement; 2) positive control (PC), soybean meal:grain sorghum supplement; 3) low-Megalac (calcium salts of fatty acids; LM) supplement; 4) high-Megalac (HM) supplement; 5) low-Alifet (crystallized natural animal fat, LA) supplement; and 6) high-Alifet (HA) supplement. Supplements were fed at .30% of BW on a DM basis and were isoenergetic within fat levels (high vs low). Steers were fed mature brome hay (7.2% CP) at 1.5% of BW on a DM basis. In the forage intake trial, heifers were assigned randomly to the same supplement treatments. Prairie hay (4.4% CP) was offered at 130% of ad libitum intake. Dry matter and NDF digestibility, ruminal DM fill, indigestible ADF passage rate, and fluid dilution and flow rates were not different (P greater than .10) among treatments. Total VFA concentrations were greater (P less than .01) and acetate-to-propionate ratio (Ac:Pr) was less (P less than .01) in supplemented groups; however, neither source nor level of escape lipid influenced either total VFA or Ac:Pr. Forage intake was greater (P less than .01) for supplemented groups than for the NC. At the high level of fat inclusion, heifers supplemented with Alifet ate slightly more (P less than .05) forage than those supplemented with Megalac.(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract

By simulating the rumen environment, the in vitro gas production technique allows characterization of DFM mediated changes in the rumen. Previous in vitro gas production experiments have focused primarily on the effects of providing Saccharomyces cerevisiae or combinations of yeast and various Lactobacilli strains and have produced variable results on the impact on gas production and the formation of endpoint fermentation end products [10][11][12]; however, there is limited data on the impact of bacterial DFM on in vitro gas production [2]. This study was designed to differentiate between immediate (in vitro, addition to fermentation vessel) and adaptive (in vivo, consumed for 28 d) effects of LAB containing DFM on ruminal in vitro fermentation of high concentrate substrates, as indicated by alterations in gas production and fermentation end products. Materials and Methods Experimental design and treatmentsAll procedures were approved by the University of Kentucky Institutional Animal Care and Use Committee. Twelve ruminally cannulated Angus steers (initial body weight 385 ± 35 kg) were used in a split-split plot design experiment (Figure 1). The whole plot consisted of steer and dietary DFM provision; the subplot consisted of the in vitro fermentation vessel and media DFM, and within sub-plot

post-fescue grazing periods is limited, especially when considering potential modulating effects related to temperament measures like exit velocity.Therefore, the objective of this experiment was to evaluate the relationship of exit velocity with growth and immune function during and following a period of grazing either toxic endophyte or non-toxic tall fescue. Materials and MethodsAll methods were approved by the University of Kentucky Institutional Animal Care and Use Committee. Animal backgroundMixed-breed beef steers (n=120; BW = 304 ± 33 kg) were purchased by order buyer from three sources. Upon arrival at the University of Kentucky's Oran C. Little Research Unit, cattle were weighed and