Effect of day or night grazing on behaviour of swamp buffalo heifers

Abstract

An experiment was conducted to examine the effect of day or night grazing on behaviour by swamp buffaloes. A grazing trial was conducted over 42 days in the late rainy season, during September to November2005 at Surin Livestock Research and Breeding Center, Surin province. The experimental period was divided into two 21-day periods. Twelve 2-year-old swamp buffalo heifers were allocated to four groups, eachcontaining three heifers, with the mean group weights being as similar as possible. Each group was allowed to graze either from 06:20 to 18:00 h (daytime treatment) or from 18:20 to 06:00 h (nighttime treatment) infour separate paddocks, each of 5 rai, using a cross-over design. When not at pasture the animals in each group were kept in the common corral with free access to fresh drinking water and mineral blocks. Individualanimal activity was recorded by visual observation at 1-min intervals during the period at pasture. Individual groups within each period were treated as replicates. Differences between group means weretested using MIXED procedure of SAS.The buffaloes on daytime treatment spent longer (P<0.05) grazing than those on nighttime treatment (423 vs 332 min). The number of meals differed (P<0.05) between treatments, but overall mean meal durationswere similar (73 min). Buffaloes allowed to graze during daylight had a tendency (P<0.10) toward a higher bite and step rates than those grazing during the night. With the reduction in grazing activity duringthe night on nighttime treatment, the animals ruminated for longer during the period at pasture (327 and 191 min, P<0.001). Live-weight change over periods of 20 days did not differ significantly. The difference intemporal behaviour patterns between treatments indicated that animals have to adapt foraging strategies appropriate for different situations in order to maintain feed intake and subsequently production