[Effects of grazing pressure on nycterohemeral ingestive behavior patterns of sheep on pasture]

The effects of grazing pressures, 4, 10 and 16 kg OM/100 kg live weight/d, on nycterohemeral ingestive behavior patterns were evaluated with six sheep, grazing a predominantly ryegrass pasture. Spectral analysis of hourly time spent chewing was performed by the use of finite Fourier transform. Distribution of hourly time spent grazing and ruminating under all grazing pressures followed periodicity of mainly 24 and 8 hours. Intake was negatively related to relative importance of 24-hours periodicity of time spent eating and it was positively related to relative importance of 12-hours periodicity of time spent ruminating. Consistent nycterohemeral distribution patterns of grazing and ruminating time were positively associated with voluntary intake of sheep.