Summary

Twenty-nine digestibility trials were carried out on various tropical forages and the results obtained were used to investigate possible prediction of nutritive value from chemical composition.1. The digestibility coefficient of crude protein could be predicted from the level of dietary crude protein. This prediction could be slightly improved by the incorporation of crude fibre in the expression. Results were somewhat higher than those reported from temperate areas.2. In order to investigate the above phenomena, a value for metabolic faecal protein was calculated. This was found to be similar to values reported from temperate areas. There was no correlation between faecal crude protein and either level of dietary crude fibre or undigested crude fibre.3. No significant relationships could be obtained to predict total digestible nutrients from either crude fibre or crude protein.4. There was a low (non-significant) negative correlation between the content of dietary crude fibre and the digestibility coefficient of organic matter; comparison of this value with those in the literature suggested that the effect of crude fibre in tropical areas was different to that reported from temperate areas.5. Results obtained were compared with standards of intake and nutrient requirements as recommended by the N.R.C. It was concluded that the factor most frequently limiting was digestible crude protein whilst total digestible nutrients were adequate in the greater part of the samples considered.

1. Cuts of elephant grass (Pennisetum purpureum were made at 40–60 (trial 1), 30 (trial 2), 50 (trial 3) and 70 (trial 4) days of age. Determinations of voluntary intake, digestibility coefficients, rate of passage through the gut, time spent eating and ruminating, number of boluses, rate of chewing, production of volatile fatty acids (both total and individual) were determined using individually housed sheep.2. Digestibility coefficients of crude protein declined with the level of crude protein in the forage; digestion of the crude fibre fraction declined with advancing maturity. The digestibility of N.F.E. increased with increasing maturity resulting in similar values for T.D.N. among the four cuts. Digestibility of dry matter of the grass in trial 2 was significantly higher than that for the other three trials.

No abstract

Using Persian Blackhead ewes, milk composition and the effect of diet on content of milk fat and milk yield were investigated. Analysis of the milk of nine ewes for fat, protein, ash and lactose (by difference) throughout a twelve-week lactation gave results which were compared with those in the literature. Average values were 5-9, 5-6, 1-0 and 4-8 % respectively. The milk of nine ewes fed on a high plane of nutrition contained significantly more fat than that of ewes fed on a low plane of nutrition; values were 8-8 and 8-3 % respectively. High plane ewes gave significantly more milk than low plane ewes. Ewes suckling twins gave significantly more milk than those suckling singles. Lambs suckling high plane ewes gained significantly more weight than those suckling low plane ewes both from birth to 3 weeks as well as from birth to 12 weeks. Male lambs gained significantly more weight than females.Highly significant correlation coefficients were obtained between milk consumed by the lamb and its gain in weight. Conversion efficiencies of milk to gain in weight were calculated and compared with literature values.