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SUMMARYThe reactions of pigs to the vibration and noise components of transport were examined with the use of an apparatus which simulated these factors. The pigs were trained to switch off the apparatus by pressing a switch panel with their snouts. It was found that vibration was aversive but that noise was not. The pigs switched off the apparatus more frequently when the vibration was fast and when they had been fed a large meal before the test. Although the sedative tranquillizing drug azaperone decreased the number of times the apparatus was switched off, the effect appeared to be non-specific because azaperone also reduced the number of responses that pigs would make in order to receive food.

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1.The nitrogen balances of thirty-six individually-housed, entire male pigs (body-weight range 19-50 kg) were measured over 7 d periods when the animals were kept initially at an environmental temperature of 22O and then at loo while fed on rations containing 153, 201 and 258 g crude protein (N x 6.25; CP)/kg dry matter (DM). The respective metabolizable energy (ME) contents were 16.29, 16.96 and 17.24 MJ/kg DM. Each ration was p e n at three levels, 20,35 and SO g feed/kg body-weight per d. The animals fed on the 20 and 35 g/kg feeding level were catheterized and blood samples withdrawn on two consecutive days within the N-balance periods for the determination of blood urea (BU) concentration both before and at hourly intervals for 7 h following the morning feed.2. An increase in feed intake resulted in a significant increase in N retention (NR) at each environmental temperature. However, NR as a proportion of N intake was higher the lower the protein content of the ration. With the exception of the animals fed on the low-protein ration, NR at any given feed intake was lower at loo than at 22O and these differences were reflected in the animal's body-weight gain.3. Values for the fasting N metabolism (N,), calculated from the relationship between NR and intake of digestible N (IDN), were temperature-dependent. At 22', a constant N, value of 0,255 g N/kg body-weight0 75 per d was found appropriate, while at loo N, increased with increase in protein content of the ration from 0.380 on the low protein ration to 0.533 and 0.753 g N/kg body-weight0 75 per d on the medium-and high-protein rations respectively. 4.The efficiency of N utilization (kN) reflected the differences in the relationships between NR and IDN. At 22O the relationship was curvilinear so that kN decreased with increase in both the level of feed intake and the protein content of the ration. At 10' the relationship was linear, hence k , was independent of feed intake within rations. However, it decreased from 0.909 to 0.679 as the protein content of the ration was increased.5. The concentration of BU attained a maximal value some 3-5 h after the ingestion of the feed, with the values at loo being higher than those at 22O. BU increased as the level of protein in the ration increased but decreased with the level of feed intake when dietary protein concentration was held constant. There was a significant correlation between BU and kN, indicating that BU is a useful criterion for assessing the efficiency of N utilization.