categoría: feed additives
autores: r. pulido, m. ruiz, f. bargo, g. tedo, r. cussen, j. acuña, j. r. roche, and i. r. ipharraguerre
libro/revista:j. anim. sci. vol. 93, suppl. s3/j. dairy sci. vol. 98, suppl. 2, 454-455.
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.