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 t wo 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 she ep 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: pellet ed high temperature dried grass of high and low digestibility, in a tw o period change-over design. Each period lasted 21 days, with total fa ecal collections being made over the final 10.5 days. Digestibility of dry matter, organic matter and digestible organic matter content of t he dry matter were significantly (P<0.01) higher in Cheviot than in Su ffolk cross animals. Animal BW, which was used as a covariate term, wa s not significant. Experiment 2 used 48 mature Suffolk cross sheep div ided into six groups according to age (range 3-8 years); each group wa s further divided into high and low BW groups. The animals were fed a single diet of pelleted high temperature dried grass. Digestibility me asurements were made as in Experiment 1. The results showed no signifi cant effect of either age, BW or any interaction between them. It is c oncluded that for the evaluation of high temperature dried grass, at l east, recognition of breed effects may be necessary.