Intake, Digestion, and Physiological Responses in Steers

An experiment was conducted to evaluate perennial ryegrass straw as a forage source for ruminants.  We evaluated digestion and physiological variables in steers offered perennial ryegrass straw containing increasing levels of lolitrem B.  Sixteen ruminally cannulated Angus × Hereford steers (231 ± 2 kg BW) were blocked by weight and assigned randomly to one of four treatments (TRT).  Steers were provided perennial ryegrass straw at 120% of the previous 5-d average intake.  Prior to straw feeding, soybean meal (SBM) was provided (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein.  Low (L) and high (H) lolitrem B straws (<100 and 1550 ppb, respectively) were used to formulate TRT diets: 100% L; 67% L:33% H; 33% L:67% H; 100% H.  Intake and digestibility of DM and OM, and ruminal pH, total VFA, and NH3-N were not affected by increasing lolitrem B concentration.  Ruminal indigestible ADF (IADF) fill increased linearly (P = 0.01) and IADF passage rate decreased linearly (P = 0.04) as lolitrem B increased.  These data suggest that feeding perennial ryegrass straw containing up to 1550 ppb lolitrem B does not adversely affect nutrient digestion or physiological response variables in steers.

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Fisher, M.J., D.W. Bohnert, C.J. Ackerman, C.S. Schauer, T. Delcurto, A.M. Craig, E.S. Vanzant, D.L. Harmon, and F.N. Schrick. 2004.  Evaluation of Perennial ryegrass straw as a forage source for ruminants.  J. Anim. Sci. 82:2175-2184. (DWB PDF#1)