AbstractChemical composition and in vivo nutrient digestibilities were determined in 30-, 45- and 60-day Guinea (Panicum maximum) and Merker or Napier (Pennisetum purpureum) grass hays. Four castrated male ruminants of each species: Holstein steers, native goat and sheep wethers, were utilized for the in vivo evaluations at each hay-age. Guinea hay showed a greater mean content than Merker hay in NOF (76.6 vs. 72.7%, P <.01), AOF (47.1 vs. 45.0%, P <.05), and C (35.2 vs. 30. 7%, P <.01 ). Merker hay was higher than Guinea hay in CP (9.1 vs. 7.8%, P <.01) and apparent digestion coefficients of CP (45.0 vs. 38.5%, P <.01), AOF (52.0 vs. 48.1%, P <.01 ) and H (68.5 vs. 61.4%, P <.01). These hays were similar in mean content of L (7.8 vs. 7.8%) and of H (Guinea, 29.5 vs. Merker, 27.7%), as well as in digestion coefficients of NOF (Guinea, 55.5 vs. Merker, 58.1%) and C (Guinea, 64.9 vs. Merker, 63.4%). Significant (P <.01) differences were obtained only for DM and C digestibilities between steers and goat wethers and between steers and sheep wethers. CP was the constituent that best predicted its digestible fraction. True NDS digestibility and bacterial and endogenous excretion values were 114.0%, 19.7%; 76.0%, 11.0%; and 76.0%, 11.0% for steers, and goat and sheep wethers, respectively.
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