Relative growth of incisor arcade breadth and eating rate in cattle and sheep

Maximum eating rate, r max in kj metabolizable energy per min, at a given body weight W kg, can be predicted in normally growing cattle when adult body weight, A kg, is known, by the formula of Taylor and Murray (1987) as r max = 31μ 0·86 A 0·73 where u = W/A is degree of maturity in body weight. When the pattern of normal growth is disturbed by fluctuating levels of food intake, a better prediction can be obtained in terms of incisor arcade breadth. This paper gives the allometric relationship between degree of maturity in body weight, u , and degree of maturity in incisor arcade breadth uD, fo r both cattle and sheep, as uD = u 0·29 . Combining this allometric relationship with that of Illius and Gordon (1987) gives the following formula for incisor arcade breadth, D u (mm), in the rth species at age, t , in relation to degree of maturity in body weight, u it , and adult body weight, A i kg): D it = 7·8 u it 0·29 A i 0·36 . Substituting u D and adult arcade breadth, D adult , for u and A in the formula of Taylor and Murray (1987) gives the following more robust formula for predicting maximum eating rate, namely, r max = 0·53 u 3 D D 2 adut .