Effects of air temperature, air velocity and feeding ...
|Title||Effects of air temperature, air velocity and feeding level on apparent digestibility, water intake, water loss and growth in calves given a milk substitute diet|
|Author(s)||M. S. Cockram, T. G. Rowan|
|Abstract||Six groups of eight, Friesian 2-day-old calves were placed successively in a controlled environment chamber. Three groups were exposed to air temperatures of 10° and 25°C. Calves were given a skim milk substitute and drinking (free) water 4 litre/day. Within each group, calves were allocated to a low (3 m/s) air velocity, and to a low or a high feeding level (DM 30 or 40 g/kg0.75 daily). At 8 days old the apparent digestibilities of DM at 10° and 25°C were 0.77 (s.e. 0.126) and 0.82 (s.e. 0.126), respectively. The apparent digestibilities of DM were greater at the low feeding level with low air velocity than for low feeding level with high air velocity or high feeding level at both air velocities (P<0.05) between which there was no significant difference. At 8 days old there were significant air temperature × air velocity and air velocity × feeding level interactions in the intake of free water. There was a significant air temperature × feeding level interaction for total water intake. Urinary water loss relative to total water intake was significantly greater at the low air velocity than at the high air velocity. In a further 2 groups of 8 calves given DM 30 g/kg0.75 daily at 8 days old, the apparent digestibilities of DM at 10° and 25° were 0.71 (s.e. 0.020) and 0.90 (s.e. 0.013), respectively (P<0.01). In the same calves given DM 40 g/kg0.75 daily at 20 days old, the apparent digestibilities of DM at 10° and 25° were 0.89 (s.e. 0.009) and 0.93 (s.e. 0.011), respectively (P<0.05). The free and total water intakes, the ratios of (total water intake - faecal water loss): total water intake and urinary losses of water were significantly greater at 25° than at 10°. Liveweight gains were lower at 10° than at 25° (P<0.01). The results indicate that air temperature, air velocity and feeding level can affect the health and growth of calves less than 4 weeks of age.|
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