Digestible Organic Matter Requirements of Ethiopian Menz Sheep: Model and Application

Abstract

Nsahlai, I.V., Osuji, P.O. and Umunna, N.N. 1997. Digestible organic matter requirements of Ethiopian Menz sheep: Model and application. J. Appl. Anim. Res., 11: 83–100.

A static model for predicting either the growth rates or digestible organic matter (DOMI) required to meet predetermined levels of growth is developed. Parameters in the model were derived using data collected in ILRI-DZ laboratory from 6 growth studies (involving a total of 242 Ethiopian Menz sheep) supported by metabolism studies.

DOMI = a W^0.75 + WG/[E_max.e^−k1w.f(WG)]; f(WG) = e^k2.KW

where a = 28.20 = Maintenance DOMI/kg W^0.75

E_max = 0.949 = is the maximum WG that can be achieved per unit DOMI

k₁ = 0.0241 = fractional decline rates of the efficiency with increasing W

k₂ = 0.0070 = fractional decline rates of the efficiency with increasing WG

W and WG = live weight and live weight gain, respectively.

The performance of the model was tested using published data, There was a good agreement between the observed and predicted requirements of tropical highland sheep, but not for sheep inhabiting the hot humid tropical habitat. The discussion suggested why some proportion of the variation in DOMI was unexplained by the model. Since the model could not account for 0.37 of the variation, it was concluded that there is scope for improvement of the model with the advent of new evidence on the subject.

Key words:

• Digestible nutrient requirements
• maintenance
• growth
• sheep
• model