อิทธิพลของขนาดกลุ่มต่อพฤติกรรมการแทะเล็มในเวลากลางคืนของกระบือปลักสาว (ต่อ)

บทคัดย่อ

This study investigated the effects of group size on night grazing behaviour by swamp buffaloes. A grazing trial was conducted over 34 days in the late rainy season, during September to October 2006 at Surin Livestock Research and Breeding Center, Surin Province. Eighteen 2-year-old swamp buffalo heifers were divided into four groups, containing three, four, five or six heifers, with the mean group weights being as similar as possible. A pasture of 20-rai was divided into 4 paddocks, the sizes of which were determined in order to maintain a stocking density of 1.1 rai per animal. The heifers were allowed onto their respective paddocks between 18.00 h and 06.00 h the following day. During daytime the animals in each group were kept in a common corral with free access to fresh drinking water and mineral blocks. Throughout the period at pasture, at intervals of 1 minute, the activity of every individual animal was observed and recorded. The total time spent grazing was not significantly affected (P>0.1) by group size. Buffalo heifers spent a mean of 480 min grazing during each 12 h period as pasture. Using 12 min of inter-meal duration as meal criterion, the number of meals and meal durations were 4 and 119 min, respectively. Heifers in large group tended to take more steps per min than in the smaller group during grazing. It is concluded that when there are limited of resources e.g. land or animals, a minimum group size of three heifers is required for studies of night grazing behaviour. Further study is needed to examine the effect of group size on grazing time when fewer than 3 animals are used.