Behavioural and physiological responses of suckling lambs to transport and lairage

The effects on suckling lambs of two stocking densities during transport (high stocking density: eight lambs per in 2; low stocking density: four lambs per m(2)) and two periods of lairage before slaughter (1.5 h and 3 It) were studied. The behaviour of lambs transported for short-duration journeys at the two stocking densities was recorded. At slaughter, blood samples were obtained after a lairage period and some physiological parameters related to stress were analysed: lactate dehydrogenase (LDH), creatine kinase (CK), calcium (Ca2+), cortisol, and packed cell volume (PCV). There was a significant effect of stocking density on lambs' behaviour during transit. The number of lambs walking was greater at low than at high density (84 and 20 observations, respectively; P < 0.001) whilst the number standing was lower at low density (852 and 366 observations, respectively). There was a significant effect (P < 0.001) of stocking density on the plasma concentration of LDH. The length of the period of lairage significantly affected plasma concentrations of LDH (P < 0.001), CK (P < 0.05), Ca2+ (P < 0.001) and cortisol (P < 0.05), as well as PCV (P < 0.01). The results show that stocking density affects the lambs' behaviour during transport. After the longer lairage period, plasma cortisol concentration is lower; mean-while, the activity of LDH and CK is higher.