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1416
A novel bm3 corn silage hybrid with floury kernel genetics improves lactational performance and feed efficiency in Holstein cows
Dry matter intake, lactation performance, feed efficiency and chewing behavior of multiparous Holstein cows (n=15) fed diets containing a novel bm3 corn silage (CS) hybrid with floury kernel genetics were compared to diets containing commercially available conventional and bm3 hybrids using a replicated 3 × 3 Latin square design with 28-d periods. Cows were housed in tie-stalls, milked 3x/d, and fed a diet containing (DM basis) 49.0% of 1 of 3 CS hybrids (Mycogen Seeds, Dow AgroSciences, LLC): 1) a conventional CS hybrid (CON); 2) a brown midrib hybrid (BMR); and 3) a bm3 hybrid with floury kernel genetics (BMRFL). All diets contained 6.3% hay crop silage and 44.7% concentrate. Diet nutrient composition averaged 14.8±0.3% CP, 2.7±0.5% NDF, and 26.3±0.5% starch. Dry matter intake and milk yield were measured on d 22-28. Milk composition was measured on d 25-26. Cow behavior was monitored for 48 h over d 24-26. Data were analyzed by ANOVA using the MIXED procedure in SAS. Dry matter intake was increased (P=0.01; SE=0.5) for cows fed BMR (28.0 kg/d) compared to CON (26.8 kg/d); DMI for cows fed BMRFL was intermediate (27.6 kg/d). Energy-corrected milk yield was increased (P<0.01; SE=1.5) for cows fed BMR (50.3 kg/d) and BMRFL (51.8 kg/d) compared to CON (47.2 kg/d). Milk fat yield was increased (P≤0.05; SE=0.06) for cows fed BMRFL (1.87 kg/d) compared to CON (1.74 kg/d) and BMR (1.80 kg/d). Milk protein yield was increased (P<0.01; SE=0.06) for cows fed BMR (1.49 kg/d) and BMRFL (1.54 kg/d) compared to CON (1.36 kg/d). Milk urea-N was reduced (P<0.01; SE=0.3) for cows fed BMR (11.61 mg/dL) and BMRFL (11.16 mg/dL) compared to CON (13.60 mg/dL). Feed efficiency (Energy Corrected Milk/DMI) was increased (P≤0.03; SE=0.04) for cows fed BMRFL (1.87) compared to CON (1.76) and BMR (1.79). Milk N efficiency (P=0.001; SE=1.2) was greatest for cows fed BMRFL (40.4%) followed by BMR (38.1%) and CON (35.3%). Cows fed CON chewed 5 min more per kg NDF consumed than cows consuming either bm3 hybrid (P<0.01). Lactational performance was increased for cows fed diets containing both bm3 CS. Greater feed efficiency indicates that a bm3 CS hybrid containing floury kernel genetics improves lactational performance and energy utilization compared to bm3 and conventional CS. Additionally, improved milk N efficiency indicates greater ruminal carbohydrate fermentability can be achieved when feeding a BMRFL diet.
Keywords: Brown midrib, floury corn, feed efficiency