Campbell,J,Baden,Stringam,et al.Pasture activities of cattle and sheep[J].Can Dept Agric Pub969315:105-112.
[11]
Scarneccia,David L,Nastis,et al.Effects of forage availability on grazing behavior of heifers[J].Journal of Range Management985,38(2):177-180.
[12]
Allden W G,W h it taker IA M.The determinants of herbage intake by grazing sheep:the interrelationship of factors influencing herbage intake and availability[J].Australian Journal of Agricultural Research970,21:755-766.