Abstract
The interrelationships between environmental temperatures and physiological reactions of sheep fed with orchard hay were investigated. The sheep and the environmental tempera-tures used for this experiment were the same as reported before.
The results obtained in this experiment were compared with those of corn silage feeding experiments, which were reported before.
1) During the feeding period, the respiration rate which increased corresponded to the increased temperature. As soon as the feed intake finished, the obvious rise of respiration rate was observed temporarily. The increased respiration rate decreased gradually after feeding period. The respiration rate changed with the change of the heat balance in the sheep body which was influenced by the feed intake and environmental temperature.
2) The respiratory minute volume increased with increasing environmental temperatures. The shape of curve on the change of minute volume within of one experiment was almost same through the each experiment. The amount of minute volume gradually lowered down in the feeding period and reached to the half amount of the largest volume, which was obtained at the end of feeding period, i. e. for five hours.
3) The heart rate increased as soon as feed intake started and became stable there-after without any gradual increased during the feeding period. Just after the finishing of the feed intake, the heart rate decreased markedly and kept about same level with a very small drop after feeding period. The influences of environmental temperatures on the heart rate were not obvious. The heart rate clearly increased during the rumination period.
4) The rectal temperature increased considerably during the feeding period and decreased with the end of feed intake in all experimental temperatures. Even under higher environmental temperatures, the rectal temperature did not rise after feeding period.
5) In the comparison between orchard hay and corn silage feeding, respiration rate, minute volume and heart rate were all higher in silage than in hay feeding under the all tested environmental temperatures. These may suggest that the physiological reactions of the sheep are affected more noticeably in the case of silage intake than that of hay intake.
