EFFECT OF BREED, AGE AND BODYWEIGHT OF SHEEP ON THE MEASUREMENT OF APPARENT DIGESTIBILITY OF DRIED GRASS

Results are reported of two experiments which examined the effect of two breed types (Experiment 1), and age and bodyweight (BW) within one breed type (Experiment 2) of sheep, on the measurement of whole tract apparent digestibility. Experiment 1 involved 16 1-year old wether sheep comprising eight Cheviot (mean BW 58.4 kg) and eight Suffolk X Mule (mean BW 69.8 kg) breed types. The animals were fed two diets: pelleted high temperature dried grass of high and low digestibility, in a two period change-over design. Each period lasted 21 days, with total faecal collections being made over the final 10.5 days. Digestibility of dry matter, organic matter and digestible organic matter content of the dry matter were significantly (P<0.01) higher in Cheviot than in Suffolk cross animals. Animal BW, which was used as a covariate term, was not significant. Experiment 2 used 48 mature Suffolk cross sheep divided into six groups according to age (range 3-8 years); each group was further divided into high and low BW groups. The animals were fed a single diet of pelleted high temperature dried grass. Digestibility measurements were made as in Experiment 1. The results showed no significant effect of either age, BW or any interaction between them. It is concluded that for the evaluation of high temperature dried grass, at least, recognition of breed effects may be necessary.