Feed intake and selection of tree fodder by dairy heifers

A trial was conducted in the central Kenyan highlands to determine the dry matter intake (DMI) by dairy heifers for napier grass (Pennisetum purpureum ) plus supplements of either fresh Calliandra calothyrsus, fresh Morus alba (mulberry), dried Manihot glaziovii (cassava tree), fresh Leucaena diversi folia (leucaena) or dairy meal. Five Ayrshire heifers were stall fed and ex posed to each diet in a latin square design, providing five replicates in f ive periods. Napier grass was supplied ad libitum and supplements at 25% of estimated daily DMI. Plant parts, twig diameters, crude protein (CP) conte nt, in vitro digestibility and, in sacco rumen degradability of consumed ma terial were determined. DMI for supplements and napier were significantly d ifferent at p < 0.05; intake of digestible crude protein, rumen degradable dry matter and digestible dry matter were significantly different at p < 0. 001. Animals were able to select pans of the tree fodder with higher conten ts of CP, higher in vitro digestibility and higher rumen degradability than the average of the offered supplement. Ash content, condensed and soluble tannins were higher but neutral detergent fibre and acid detergent fibre co ntents were lower in offered than left over vee fodder. Thickness of consum ed branches increased with rainfall figures and measured up to 5 mm for leu caena, 9 mm for mulberry and 12 mm for calliandra. Studies such as this one will enable researchers to estimate the feeding values of different fodder trees and enable them to recommend optimum rations including these fodders . Through comparison of DMI, indications of palatability of tree fodders ca n be obtained. Of the fodder vee species tested in this experiment, mulberr y and cassava tree had the highest potential in terms of milk production le vels. Experiments are needed feeding these two species to lactating cows. ( C) 1999 Elsevier Science B.V. All rights reserved.