categoría: feed additives
autores: merrill, c., windle, m.c., souza, w.f., ipharraguerre, i.r., and kung, l.
libro/revista:journal of dairy science vol.96 e-suppl.1: 424
the objective of this study was to evaluate the effect of improving forage palatability on dm intake, milk production and composition, and rumen ph of lactating cows. twenty one multiparous and 7 primiparous holstein cows averaging 697 kg in body weight (sd ± 81), 54 dim (sd ± 32), and consuming 23 kg dmi (sd ± 8) were fed a base tmr comprised of 45% corn silage, 10% alfalfa haylage, and 45% concentrate. after a 2-wk adjustment period, cows were blocked by production, parity, and dim and randomly assigned to one of two treatments for 10 wk. each treatment had two cows with previously fitted rumen fistula. in-dwelling probes were placed in the rumens of the fistulated cows, once weekly, and rumen ph was measured every 30 min for 48 h. for one half of the cows, the forage portion of the diet was pretreated with a palatability enhancer (luctarom sbs-r, lucta, s.a., spain) that was premixed in water to achieve a projected dose of 12 ml/cow/d prior to mixing into a tmr (trt). the remaining half of the cows was fed a similar tmr but the forage was mixed with water only (ctrl). production data were analyzed as a completely randomized and covaried with pre-treatment values. rumen ph was analyzed in a factorial design with repeated measures with treatment, week, and treatment x week as main effects. for all animals, there were no differences (p > 0.05) between treatments for dmi and milk production and composition. however, when data from only multiparous animals were analyzed (n = 10 for trt and 11 for ctrl) there was a tendency for greater dmi ( 1.5 kg/d, p < 0.07) and milk production ( 3.9 kg/d, p < 0.10) for cows fed trt. compared with ctrl, cows fed trt had higher (p < 0.01) mean rumen ph and spent less time (p < 0.02) throughout the day with ph below £ 5.8. there was no difference between treatments in particle size distribution of the tmr throughout the day as evaluated with a psu particle size separator box. improving the palatability of the forage fraction of the tmr fed to multiparous dairy cows may help to stabilize the daily pattern of ruminal ph and increase dmi and milk production.