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 diversifolia (leucaena) or dairy meal. Five Ayrshire heifers were stall fed and exposed to each diet in a latin square design, providing five replicates in five periods. Napier grass was supplied ad libitum and supplements at 25% of estimated daily DMI. Plant parts, twig diameters, crude protein (CP) content, in vitro digestibility and, in sacco rumen degradability of consumed material were determined. DMI for supplements and napier were significantly different 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 parts of the tree fodder with higher contents 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 contents were lower in offered than left over tree fodder. Thickness of consumed branches increased with rainfall figures and measured up to 5 mm for leucaena, 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 can be obtained. Of the fodder tree species tested in this experiment, mulberry and cassava tree had the highest potential in terms of milk production levels. Experiments are needed feeding these two species to lactating cows.