文摘
The time budgets and daily milk yield of Jersey and Friesland cows and their crosses were compared in a pasture-based system by recording the time spent grazing, drinking, lying, standing and walking in four seasons of the year (cool–dry, hot–dry, hot–wet and post-rainy). Observations were made from 0800 to 1400 hours on seven cows per breed. Seven observers monitored the cows at 10-min intervals for 6 h using stop watches. Time spent standing was higher (P < 0.05) for Friesland compared to Jersey cows and the crossbred cows during the hot–wet season. Time spent walking differed among the three genotypes with the Jersey spending more time (P < 0.05) in both hot–wet and cool–dry seasons. No differences were noted on time spent lying down (P > 0.05) across the genotypes in the hot–wet season. In the cool–dry season, differences in time spent grazing (P < 0.05) were noted with the Jersey cows spending more time. The Friesland and the crossbred spent more time lying down (P < 0.05) than the Jersey cows in the cool–dry season. No time differences were noted for time spent standing (P > 0.05) in the same season. The Jersey cows spent the longest time walking (P < 0.05) during the cool–dry period. There were seasonal differences in time spent in all activities (P < 0.05). Time spent on grazing was longest in post-rainy season and lowest in hot–wet season. Differences were observed in the time spent lying down (P < 0.05). The longest period was observed in the hot–dry season and lowest in the hot–wet season. Daily milk yield varied (P < 0.05) with breed with the Friesland and Jersey producing higher yields than the crosses. The highest amount was produced in hot–dry and the least in hot–wet season. Milk yield and lying down were positively correlated (P < 0.05) in Jersey and Friesland cows. Standing was negatively correlated with milk yield (P < 0.05) in both Friesland and Jersey cows. No significant relationship was observed for the crossbred cows. It was concluded that the genotypes show different levels of sensitivity to seasons and that a relationship exists between milk yield and time budgets.