Nutrition and Beef Production of Fattening Young Steers on Pasture : I. The body weight gains and nutrient intake of fattening young steers on the temperate grass pasture

In order to solve the technical problems of a newly-improved beef production system which composed of rearing on pasture and finishing in drylot, for reducing the cost of feeds and saving labor, a series of experiments has been conducted since 1960 to 1972 at Kyushu Agricultural Experiment Station. The study reported herein is the 1st report of this series, and the objective of this study was to know the relation between body weight gain and nutrient intake by fattening young steers on the temperate grass pasture. Two 8-month-old Japanese Brown steers, 209.5, 206.5kg of body weight, were employed in rearing test under rotational grazing at 15 days interval on the experimental pasture with no supplemental feeds from April 1 to September 27 in 1960. The experimental pasture of 37.5 a was divided into fifteen paddocks of 2.5 a having mixture or Orchard grass, Tall fescue and Ladino clover (seeding rate: 0.2, 0.1 and 0.1kg per a, respectively). The experimental results obtained were summarized as follows: 1. Vegetation and its nutrient contents were changed according to conditions, in particular, to growing seasons. During summer, the percentage of grasses in pasture decreased gradually, and that of legume rapidly increased. The crude fiber percentage of grazed herbage on dry matter basis increased gradually from April to June, and subsequently, decreased rapidly with decline in percentage of grasses from July to September. The change of crude protein percentage was in contrast to that of crude fiber throughout the experimental period. These trends were apparently influenced by the changes of botanical composition in pasture. 2. The average daily gain was greatly varied from 0.14kg to 1.65kg between split periods, and less body weight gain was obtained in the latter half of June and the former half of September. The average daily gain in the whole grazing periods was 0.78kg, and the change of body weight gain roughly corresponded to that in digestibility of the organic matter of the forages. 3. Forage intake of young steers on pasture depended on the air temperature, rainfall, and quality and quantity of forage. The green forage intake estimated by chromogen method ranged from 16.3kg to 32.8kg per head a day. The herbage intake on air dry matter basis per head a day averaged 1.8kg per 100kg live-weight in the whole grazing periods. 4. The digestibility of grazed forage was decreased owing to higher air temperature and higher percentage of crude fiber of herbage. The digestibility of organic matter of pasture herbage varied from 81.8 percent in early spring to 42.1 percent in midsummer. 5. Daily gain in each grazing period was in precisely accordance with ADM, DCP and TDN intake. The ratios of ADM, DCP and TDN intake to the Japanese feeding standard for short yearling averaged 71, 136 and 59 percent, respectively, in the whole grazing period. Especially, ADM and TDN intake were insufficient throughout the grazing periods, except in April. 6. Water intake of the steers ranged between 3.5kg and 23.5kg and increased with higher air temperature, less rainfall and lower percentage of the moisture in the herbage. Total consumption of water derived from water bowl and herbages was between 24.1kg and 40.0kg per head a day, corresponding to about 10 percent of the body weight in each grazing period.