Whole-plant corn silage and foliar fungicide: Strategies to improve dairy feed quality and profitability

Dairy cow numbers have been on the decline for some time now; however, milk production continues to climb. This increase in efficiency can be attributed to genetic advancements, improvements in management, and the utilization of nutritional strategies. The most important of these is to feed high-quality ingredients in a properly-formulated total mixed ration (TMR). In the Midwest, a popular ingredient to include in TMR is whole-plant corn silage (WPCS), which is often sprayed with foliar fungicide during growth to decrease disease incidence. Therefore, the objective of this research was to determine if different corn hybrids treated with foliar fungicide and harvested as WPCS affect performance of lactating cows and profitability of operations. Thirty-two lactating cows were assigned to 4 treatments in a replicated 4 × 4 Latin square design balanced to measure carryover effects: brown midrib (BMR) or floury (FLY) WPCS with foliar fungicide application (FUN) or without foliar fungicide application (CON). Foliar fungicide application (pyraclostrobin + metconazole; Headline AMP, BASF, Florham Park, NJ) occurred at vegetative tassel growth stage. Whole-plant corn silage was inoculated (Silo-King; Agri-King, Fulton, IL) upon bagging (Ag-Bag; Ag Bag Systems, St. Nazianz, WI) and ensiled for 295 d prior to feeding. Dry matter intake was similar for cows consuming all corn hybrids and treatments (P > 0.15). Milk yield, 35.0 g/kg fat-corrected milk yield (FCM), and energy-corrected milk yield (ECM) were greater (P ≤ 0.05) for cows consuming CON (milk yield = 33.4 ± 0.56 kg/d; FCM = 34.7 ± 0.68 kg/d; ECM = 33.8 ± 0.65 kg/d) compared to those consuming FUN (milk yield = 32.3 ± 0.55 kg/d; FCM = 33.8 ± 0.67 kg/d; ECM = 32.7 ± 0.65 kg/d) for both corn hybrids. Apparent total-tract digestibilities of organic matter (OM) and crude protein (CP) were greater (P ≤ 0.01) for cows consuming CON (OM = 773 ± 2.97 g/kg; CP = 775 ± 3.37 g/kg) compared to those consuming FUN (OM = 763 ± 2.97 g/kg; CP = 754 ± 3.34 g/kg) for both corn hybrids. Apparent total-tract starch digestibility was greater for cows consuming FUN compared to those consuming CON and greater (P < 0.01) for cows consuming BMR compared to those consuming FLY (FUN = 983 ± 0.81 g/kg; CON = 979 ± 0.80 g/kg; BMR = 983 ± 0.81 g/kg; FLY = 979 ± 0.80 g/kg). Apparent total-tract digestibilities of OM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) were greater (P ≤ 0.01) for cows consuming BMR (OM = 774 ± 2.97 g/kg; NDF = 563 ± 5.31 g/kg; ADF = 532 ± 6.10 g/kg) compared to those consuming FLY (OM = 762 ± 2.97 g/kg; NDF = 543 ± 5.31 g/kg; ADF = 500 ± 6.12 g/kg) for both fungicide treatments. Total urinary N excretion was greater for cows consuming FLY compared to those consuming BMR and greater (P = 0.02) for cows consuming CON compared to those consuming FUN (FLY = 239 ± 6.32 g/d; BMR = 225 ± 6.30 g/d; CON = 239 ± 6.30 g/d; FUN = 225 ± 6.32 g/d). Under economic evaluation, FUN resulted in a numeric decrease in income over feed cost (IOFC) for both corn hybrids due to the added cost of fungicide application. Cows in BMR/CON generated the greatest IOFC because of a greater milk yield and a slightly decreased feed cost. In conclusion, increased nutrient digestibility for cows in CON resulted in increased milk yields with similar intakes. The increased digestibility for cows consuming BMR WPCS caused a decrease in N excretion. This ultimately resulted in a greater IOFC for cows in CON compared to those in FUN.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste