Pasture productivity in Nigeria: II. Voluntary intake and herbage digestibility

Abstract

SUMMARYThe organic-matter intake and the digestibility of grazed tropical pasture mixtures were assessed by the chromic oxide-faecal organic matter-nitrogen technique in five digestion trials. The pasture treatments were designated as: H, Cynodon nlemfuensis var. robustus in a mixture with the legumes Centrosema pubescens and Stylosanthes gracilis; J, Pennisetum purpureum in a mixture with the two legumes in H; K, treatment J plus Panicum maximum; L, a mixture of all the grass and legume species in treatments H, J and K.The mean organic-matter digestibility of the herbages was determined in indoor digestion trials during the experimental period and varied from approximately 60·0 ± 1·73% to 62·7 ± 4·18% in treatments K and H respectively, with treatments J and L falling between these two values. The mean digestibility of the herbage as grazed, however, was approximately 66·8 ± 1·72, 69·7 ±7·68, 67·1 ± 4·40 and 67·4 ± 4·15 % for treatments, H, J, K and L respectively.The estimated mean intake of organic matter was somewhat lower, while that of the digestible organic matter was appreciably lower than those reported for animals of corresponding live weights in temperate countries. Grazed pastures were better digested by 4·1 digestibility units in treatment H, by 7·1 in both J and K, and by 5·3 units in L, compared with the indoor digestion trials.More intensive studies are still needed to warrant any justifiable conclusion as to whether the low intake of herbage by tropical cattle is due primarily to the high crude fibre and the low nutritional values of the pastures, or to the inherent capacity of the animals conditioned to grazing poor·quality pastures.