Two experiments investigated the welfare of pigs during transport. In experiment 1, 12 groups offour 90-kg pigs were transported to slaughter in a commercial livestock lorry for 1·5 h. Half the animals were transported in their social groups (unmixed condition) and half were transported with groups of previously unfamiliar pigs mixed together (mixed condition). Behaviour was recorded, a general activity index scored and saliva samples taken at different stages of the journey for analysis ofcortisol. Pigs spent most of their time standing in both conditions. The journey was very rough (as revealed by characterization with an accelerometer) and in the unmixed condition the pigs appeared to stand to reduce travel sickness. In contrast, in the mixed condition, this preference for standing seemed to be due to fighting which stressed and exhausted the animals (the general activity index was three times the unmixed condition). Levels of salivary cortisol were higher in the mixed condition at the beginning, middle and end of the journey. In experiment 2, six 35-kg pigs, prepared in advance with jugular vein catheters, were loaded onto a commercial livestock lorry (09.30 h) where they were individually penned. The vehicle remained stationary with the engine off and blood samples were taken at 30-min intervals during the next 8 h (control). Two days later this procedure was repeated while the vehicle was driven for 8 h (on main roads and motorways). Plasma concentrations of cortisol and beta-endorphin increased markedly in both conditions immediately after loading. Cortisol levels were greater (relative to control) at the beginning, in the middle and at the end of the journey. Concentrations of beta-endorphin did not differ between control and experimental conditions except during the final 180 min of the journey when the control levels were higher.

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Two experiments were made to investigate the effects of road transport on stress hormone responses in pigs. In experiment 1, seven 40-kg pigs, prepared with jugular catheters, were loaded onto a livestock lorry and transported over a 2-day period on routes characterized, by means of an accelerometer, as rough or smooth. Two 100-min journeys, one rough and one smooth, separated by a 100-min rest period, were conducted each day. The experimenters travelled with the animals and blood samples were taken for hormone analysis from each pig at 20-min intervals. On the 3rd day, samples were collected from the pigs when housed in their home pen (control). Plasma concentrations of cortisol increased after loading, remained higher for longer on rough compared with smooth journeys and were higher during both journeys on day 1 compared with day 2. Concentrations of beta-endorphin increased after loading on day 1 but neither beta-endorphin nor lysine vasopressin showed clear changes in secretion pattern during rough or smooth journeys. On day 3 (control), mean concentrations of all three hormones were significantly lower than on days 1 and 2, indicating that the responses observed were not due to a diurnal rhythm. In experiment 2, six 35-kg catheterized pigs were loaded on a lorry (09.30 h) that remained stationary while blood samples were taken at 30-min intervals during the next 8 h (control). Two days later, this procedure was repeated with the vehicle in motion for 8 h. Plasma concentrations of lysine vasopressin during driving increased between 2 and 4·5 h which coincided with behavioural observations indicating that the pigs were travel sick.

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Melatonin was administered intravaginally in Silastic tubing to adult and prepubertal ewes. In Exp. 1, ewe lambs (born early March) were given intravaginal melatonin implants at a mean age (+/- s.e.m.) of 7.5 +/- 0.1 weeks (Group E, N = 10) or 19.4 +/- 0.2 weeks (Group L, N = 10). The third group (Group C, N = 10) received empty implants. In Exp. 2 mature ewes were given implants on 13 May (Group E, N = 10) or 18 July (Group L, N = 10) or received empty implants (Group C, N = 10) on one of these two dates. Blood samples were taken twice weekly for progesterone assay. In Exp. 1 the mean age (+/- s.e.m.) at puberty (progesterone greater than 2 nmol/l for two consecutive samples) was 35.4 +/- 0.8 weeks. Puberty was advanced by 5.2 weeks in Group L lambs, occurring at a mean age of 30.2 +/- 0.7 weeks (P less than 0.001). In Group E lambs the timing of puberty was unaltered, occurring at a mean age of 34.8 +/- 0.6 weeks. Mature ewes in Group L (Exp. 2) showed increased incidence of ovarian activity (9/10 ewes cycling by 26 September) compared with the control ewes (1/10) (P less than 0.001), but there was no effect in Group E ewes (3/10). The results demonstrate that continuous melatonin administration to adult and prepubertal ewes can mimic the effect of short days in terms of the reproductive response, and that the present and previous exposure to melatonin is critical in determining the response.