Production response to corn silage produced from normal, brown midrib, or waxy corn hybrids

The objective was to evaluate the nutrient intake and digestibility and milk production response of lactating dairy cows fed diets based on corn silage produced from 3 different types of corn hybrids. Experimental diets contained 36.4% of the dietary dry matter (DM) from corn silage produced from normal (Agratech 1021, AgraTech Seeds Inc., Atlanta, GA), brown midrib (BMR; Mycogen F2F797, Mycogen Seeds, Indianapolis, IN), or waxy (Master's Choice 590, Master's Choice Hybrids, Ullin, IL) hybrids. Thirty-six multiparous and primiparous Holstein cows (66 +/- 22 d in milk, 41 +/- 8 kg/d of milk) were used in an 11-wk completely randomized design trial during the fall of 2009. All cows were fed a diet containing normal corn silage during the first 2 wk of the trial before being assigned to 1 of 3 treatments for the following 9 wk. Data collected during the first 2 wk were used as a covariate in the statistical analysis. No difference was observed in dry matter intake (DMI) among treatments, which averaged 22.6 kg/d. Milk yield was higher for cows fed BMR (37.6 kg/d) compared with waxy (35.2 kg/d) but was similar to that of cows fed control (36.2 kg/d). Milk fat percentage tended to be lower for cows fed control (3.28%) compared with those fed BMR (3.60%) or waxy (3.55%) corn silage. Milk protein percentage tended to be lower for cows fed control (2.79%) compared with waxy (2.89%) but similar to that of those fed BMR (2.85%). No differences were observed in yield of milk components. Energy-corrected milk (ECM) yield and dairy efficiency (ECM:DMI) did not differ among treatments. Cows fed BMR tended to gain more body weight compared with those fed control and waxy. Results of this trial are consistent with previous reports in which cows fed diets based on corn silage produced from BMR hybrids have higher milk yield compared with those fed other hybrids. Corn silage produced from the waxy hybrid supported a similar yield of ECM because of higher milk components, but milk yield was not improved compared with the control.