Título en español.

Forty-eight lactating Holstein cows were randomly distributed on four treatments at the Gurabo Substation: T8 , grazing; T9 , grazing + 2.3 kg per day of dehydrated, whole-plant maize (Zea mays) pellets; T10, grazing+ 2.3 kg per day of Stargrass (Cynodon nlemfuensis) hay; and T11, drylot feeding of Stargrass hay + 4.5 kg per day of pelleted maize, to evaluate preserved fOrages in terms of variations in pasture quality. Grazing was at the rate of five cows per ha. Cows in all groups received concentrates at the rate of one unit of concentrate to two units of milk. The cows started on the treatments at 45 days postpartum. Analysis by covariance showed significant treatment effects in milk yield with pretrial production as the covariate. The adjusted means for daily milk yield over an 8-week period were 23.2, 23.8, 23.1 and 23.1 kg for T8, T9, T10 and T11, respectively. Treatment effects were not significant for either fat percent or body weight gain. Cows fed hay, pellets and concentrates (T11) equaled those on grazing plus concentrates (T8) in milk yield, but cows on grazing supplemented with concentrates and pelleted forages (T9) were significantly higher in milk yield. Cows on grazing supplemented with hay and concentrates (T10) were significantly lower in milk yield. The study showed that good quality pelleted forages may be used effectively in combination with pasture of hay. However, tropical grasses, cut at 45 to 55 days of age and artificially dried, have limitations in nutritive value and palatability for use in conjunction with good quality pastures.