A SENSORY ADDITIVE INCREASES MILK AND PROTEIN RESPONSES TO CONCENTRATE SUPPLEMENTATION IN GRAZING DAIRY COWS

Forty 5 Holstein dairy cows (62 DIM, 501 kg BW) were assigned to a 3 × 2 incomplete Latin square (LS) design replicated 15 times to evaluate the effect of a sensory additive (ProEfficient, PE) on milk response to concentrate supplementation on pasture. Cows were blocked by parity in 15 blocks and within blocks randomly assigned to 3 concentrate treatments: 1 kg/d mineral concentrate (MC); 7 kg/d starch-based concentrate (CC); and 7 kg/d of CC with 30 g/d of PE (PEC). Cows grazed a perennial ryegrass pasture during 56 d divided into 2 28-d periods. Targeted herbage allowance and pre grazing herbage mass were 25 kg DM/cow and 2400 kg DM/ha, respectively. Concentrates were fed twice daily at milking. The MC was composed of 60% wheat/barley/oat mix, 10% rapeseed meal, and 30% of a mineral premix, and averaged 10.4% CP, 17.2% NDF, and 64.3% in vitro DM digestibility (IVDMD). The CC and PEC were composed of 65% corn, 13.5% triticale/oat/wheat mix, 10% soybean meal, 5% rapeseed meal, 2% sugar beet molasses, and 4.5% mineral premix, and averaged 14.1% CP; 14.7% NDF, 88.4% IVDMD. Ryegrass pasture averaged 22.3% CP, 41.9% NDF, and 77.7% IVDMD. Data were analyzed using a mixed model that included the fixed effects of treatment, block, period, their 2-way interactions, and the random effect of cow within block. On average, supplementation with the starch-based concentrate increased (P < 0.05) milk yield 4.4 kg/d compared with MC (24.3 vs. 28.7 kg/d, SEM 0.284). However, cows supplemented with PEC produced more (P < 0.05) milk than CC cows (29.0 vs. 28.4 kg/d, respectively; SEM 0.284) because the milk production response to concentrate supplementation was improved 16% (P < 0.05) by the addition of PE into the concentrate (0.79 kg vs. 0.68 kg milk/kg concentrate for PEC and CC, respectively). Supplementation with PEC also increased (P < 0.05) milk protein percentage (3.74 vs. 3.43%, SEM 0.11) and yield (1.084 vs. 0.978 kg/d, SEM 0.039) compared with CC. The milk and protein responses triggered by PE might be associated with a reduction in the substitution rate of CC for pasture or changes in the concentration of the orexigenic hormone ghrelin. tech.service@fad.com