The nutritive value of Persian clover (Trifolium resupinatum) herbage grown under irrigation in northern Victoria

Abstract

A series of experiments is described which considered the nutritive value of Persian clover (Trifolium resupinatum) (cv. Maral) herbage grown under irrigation in northern Victoria. Digestion studies were undertaken with sheep and dairy cows, and the degradation of herbage samples in nylon bags was evaluated. Digestion coefficients were estimated, leaf and stem characteristics were measured, mineral and amino acid profiles were obtained, and protein degradabilities were assessed throughout the period of growth of Persian clover. Freshly harvested Persian clover herbage utilized before flowering appears to be an excellent feedstuff for ruminants, and its chemical composition remains relatively constant until late spring. In vivo OM digestibilities were in the range, 75-85%, although this depended on feeding level and time of the year. When vegetative, nitrogen content ranged from 3.0 to 4.6%, and neutral and acid detergent fibre levels were 24-34 and 21-27%, respectively. Acid detergent lignin concentrations were between 2.1 and 4.5% of dry matter. Dry matter contents of the herbage were often very low; this could influence intake and digestion. The chemical composition of leaves and petioles/stems were very different. The digestibility of the leaf fraction was often much lower than that of the petiole/stem fraction, but its nitrogen content was higher. Reasons for this, and their implications, are discussed. Protein degradability in the rumen was lower than expected (<70%); this was attributed to very fast rates of flow of digesta out of the rumen. Herbage minerals generally appeared to be adequate. Implications of the degree of degradation of individual amino acids and minerals in the rumen are discussed. The use of chemical characteristics to predict the digestibility of Persian clover herbage is considered and discussed.