8 Impact of Increasing Level of Milk Production on Cow and Calf Performance in the Nebraska Sandhills

Abstract Selection for increased milk production across the United States has resulted in variable cow and calf productivity responses. The growth response variability may be due to relationship between forage intake, which nursing grazing behavior help explain. objectives of this study were determine impact increasing level on body weight (BW), condition score (BCS), reproductive performance, growth, nursing, behaviors Nebraska Sandhills. In a 2-yr study, data collected 118 mature crossbred cow-calf pairs from March- May-calving herds. On approximately 30, 60, 90, 120, 210 d postpartum, individual 24-h yield was estimated through weigh-suckle-weigh techniques. Cow BW BCS 14 prior calving, weekly 30 breeding, at weaning. Calf recorded each milking. determined during 3-wk periods EARLY (65.4 ± 10.0 d) LATE (162 22.3 lactation using high frequency (1 hz) global positioning system (GPS) with neck collars. Milk area under curve values calculated total all variables analyzed linear regression analysis. BW, change, performance not (P > 0.12) associated production, except tendency = 0.09) lower breeding production. At weaning, negatively 0.02) but any other physiological stage. percent time spent affected 0.33) by dam However, exhibited 0.10) decrease Pre-weaning positively < 0.01) weigh date. A positive association average daily gain (ADG) observed 0.04) birth age 120 only steer ADG finishing phase 0.63) environmental conditions, had increase pre-weaning without negative reproduction.