ABSTRACT
Summary Uncertainty exists about whether drought is detrimental to the nutritive quality of herbage. This paper tries to resolve this uncertainty by examining the influence of soil moisture on some herbage-quality characteristics. Unpublished data from my own work and review of published literature are presented. Field plots of three tropical grasses, green panic (Panicum maximum var. trichoglume), buffelgrass (Cenchrus ciliaris), and speargrass (Heteropogon contortus), were subjected to periods of controlled drought, and herbage from these plots was compared with that from well-watered plots. Leaf and stem dry-matter digestibility of water-stressed herbage was either similar to or higher than that of unstressed herbage. Sward digestibility in plots subjected to drought was higher than that in the well-watered controls because of a decreased proportion of stem and a higher digestibility of both leaf and stem. A review of the published literature indicates that low soil moisture rarely has an adverse effect on herbage quality. Available information leads to the conclusion that animal live-weight gain should be better than usual under conditions of low soil moisture unless low pasture yield seriously restricts intake. Information from a grazing experiment in Australia supports this contention.
