1991 Fiscal Year Final Research Report Summary
Variation among regeon and season in energy balance of grazing haifers.
| Project/Area Number |
01480092
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
畜産学(含草地学)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OKUBO Tadakatsu The Univ.Tokyo, Dept.Agric.Sci., Professor, Ph.D., 農学部, 教授 (90115535)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAKAWA Morihiko Ryukyu University, Assistant Professor, 農学部, 助手 (90175555)
MATSUI Kanji The Univ.Tokyo, Dept.Agric.Sci., Assistant Professor, 農学部, 助手 (50126166)
SAWASAKI Tohru The Univ.Tokyo, Dept.Agric.Sci., Assoc.Professor, 農学部, 助教授 (00012047)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Production gross efficiency / Energy balance of grazing heifers / grazed grassland, Tallfescue / Ryegrass pasture / Metabolizable energ efficiency and grass species |
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| Research Abstract |
Seasonal changes in efficiency of solar energy fixed on grazed pasture of tallfescue (Festuca arundinacea Schreb.) was investigated. Threughout growing season from late March until late October in 1986-1987,0.78% of incident solar energy (3017 GJ/10a and 2843 GJ/10a, respectively) was fixed in herbage available, 0.76% was consumed by grazing Holstein heifers and 0.021% was retained in heifers'body. At every step of energy conversion in plant and animal growth, the values of efficiencies were highest in spring grazing season and lowest in summer grazing season.
Relation among herbage energy supply (HA), grazing intensity (GI) based on fasting metabolism, and consumed herbage energy (HCE) was expressed as followsing equations :
in spring and autumn HCE=12.3GI-49.2GI^2/HA-0.709 (R^2=0.94)
in summer HCE=-3.58GI+46.7GI^2/HA+3.43 (R^2=0.69)
Here, the HA is the sum of HCE and the amount of residual herbage available left uneaten at the end of each grazing peirod. Fasting metabolism was calculated by ARC (1980)'s method.
These seasonal variation in both HCE and IVDMD,which were relating negatively with air temperature, were regarded to be a main cause of the seasonal change in solar energy conversion efficiency for secondary production of grazing helfers.
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