Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 11/14/2008
Publication Date: 8/16/2009
Citation: Beck, P., Stewart, B., Gunter, S.A. Effect of wheat forage maturity and preservation on the performance of and digestion kinetics in growing beef calves fed 40% roughage diets. Journal Animal Science. 87(E-Suppl. 3):17. (Abstract)
Technical Abstract: Wheat (Triticum aestivum L.) forage was harvested at the boot or dough stage of maturity, preserved as hay or round-bale silage, and fed to calves in 40% dry matter(DM) basis) roughage diets. Forty-eight growing beef steers (body weight (BW)=199 ± 6.8 kg) were fed for ad libitum consumption for 49 d in a 2 x 2 factorial arrangement with 3 pens/treatment. Also, to determine digestion kinetics and digestibility of the diets, 16 calves (BW=160 plus/minus 8.2 kg) were individually fed 2.0% of BW dry matter (DM basis) of experimental diets for 10 d followed by a 5-d fecal collection period in a completely randomized design. Fecal excretion curves were analyzed by nonlinear regression procedures in SAS using a one-compartment model (Marquardt method) for determination of ruminal passage kinetics. Acid detergent insoluble ash was used as an internal marker to determine diet DM and NDF digestibilities. Animal performance data were analyzed as a completely randomized design using the mixed procedure in SAS. Pen within forage maturity by preservation method was used in the random statement. Feed intake, grain:feed (G:F), digestibility, and digestion kinetics were analyzed using the GLM procedure of SAS. Average daily gain (1.8 ± 0.05 kg) was unaffected (P equal or greater than 0.22) by maturity, preservation method, or their interaction. Maturity at harvest did not impact (P equal or greater than 0.26) dry matter intake (DMI) (2.93% of BW, DM basis) or G:F (0.25 kg gain/kg feed). Calves fed hay consumed more feed (P = 0.04) than calves fed silage as a percentage of BW (3.1 vs 2.8%, respectively), but tended (P = 0.09) to utilize feed less efficiently (0.24 vs 0.26 kg feed/kg gain, respectively). Diets containing dough-silage were less digestible (P equal or less than 0.05) than hay diets and tended (P = 0.07) to be less digestible than boot-silage diets. These results indicate that wheat forage harvested at these 2 stages and preservation method has no affect on animal performance of growing beef steers when fed in a 60% concentrate diets, but may affect DMI, G:F, and digestibility.