Influence of Grazing Conditions of Native and Tame Pasture on Live-Weight Gain of Steers of Two Breeds (Japanese Black and Holstein)

Abstract

Grazing experiments were carried out on both native and tame pastures to compare the growing ability of the two cattle breeds (Japanese Black and Holstein). During each of two consecutive grazing seasons 12 steers (6 each of two breeds) of about 20 months old were grazed alone on each of both pastures and investigated as for live-weight gain. For steers grazed on native pasture the grazing behaviour was observed and the grazing intake was estimated by the method of chromic oxide and chromogen in spring and autumn of the second year. The results obtained were as follows. 1) Daily gains on native and tame pastures were respectively 0.30kg (first year), 0.4kg (second year) and 0.47kg, 0.51kg for Black steers, and 0.52kg, 0.56kg and 0.92kg, 0.70kg for Holstein steers. These figures show that daily gains of Holstein exceeded those of Black on both pastures and daily gains on tame pasture exceeded those on native pasture for both breeds. However the difference between gains on both pastures was much more for Holstein than for Black. Therefore it can be mentioned that Black steers utilized native pasture relatively better than Holstein steers. 2) Steers of two breeds on native pasture behaved usually in one group, but were apt to break up into two groups of each breed at two grazing peaks in morning and evening. In the case of grazing on the steep slope Black steers walked ahead of Holstein. 3) Estimated daily intake (D.M.) in spring was reasonable (7.4-7.5kg), but that in autumn was very little (4.4-4.8kg). This abnormally limited value in autumn was presumably caused by reason that chromogen in herbage was considerably changed or absorbed while passing through the gastrointestinal organs. From this point it seemed extremely questionable to use chromogen as indicator for the estimation of digestibility.