Relationships between age, liveweight and liveweight gain of Japanese Black heifers and steers grazing a bahiagrass pasture under supplementation at the Sumiyoshi Livestock Farm
Hirata, M.; Fukuyama, K.; Higashiyama, M.
Bulletin of the Faculty of Agriculture, Miyazaki University 42(1-2): 51-61
ISSN/ISBN: 0544-6066 Accession: 002942410
To analyse and characterize the Japanese Black heifer/steer system on the Sumiyoshi Livestock Farm, relationships between age and liveweight gain (LWG) were investigated. Cattle grazed a bahiagrass (Paspalum notatum) pasture from May to October or November with supplementation. There was a positive linear relation between liveweight and age. From the start to the end of the grazing season, the regression equations significantly differed in the intercept and slope. The intercept was smaller and the slope was greater at the end of the grazing season than at the start. These equations provided 2 mathematical implications. They were the relations between LWG over the grazing season and initial age, and between the favourable feeding conditions in the grazing season and initial age. When compared with the growth curve of Japanese Black cattle on temperate pastures, most cattle had liveweights between the mean and the lower limit of the curve, and some younger cattle were below the lower limit particularly at the end of the grazing season. The older or heavier cattle tended to gain more than the younger or lighter cattle and steers tended to gain more than heifers though there were considerable animal-to-animal variations even within a class of the same sex and similar ages and liveweights. The greater LWG in older or heavier cattle was considered to reflect advantageous competition for supplements.