The effects on stickling lambs of two stocking densities during transport (high stocking density: eight lambs per m2; low stocking density: four lambs per m2) and two periods of lairage before slaughter (1.5 h and 3 h) 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; meanwhile, the activity of LDH and CK is higher.

To evaluate the effect of stocking density and transport time on physiological responses and meat quality, 72 male suckling lambs were transported by road to the slaughterhouse at three different stocking densities (0.12, 0.20 or 0.25 m2/lamb) and two transport times (5 h or 30 min). Blood samples were collected pre-transport at the farm and after unloading in the slaughterhouse to measure levels of cortisol, creatine kinase (CK) and lactate dehydrogenase (LDH). After slaughter, the weights of the hot carcass, liver and spleen were recorded and pH in Musculuslongisimus thoracisetlumborum (L), Musculussemitendinosus (ST) and Musculuspsoas major (PM) were determined. Colour, water-holding capacity (WHC), texture and thiobarbituric acid-reactive substances (TBARS) values were measured in samples of L, at 24 h post mortem and after 5 days of ageing. Cortisol and LDH were higher in suckling lambs transported for 30 min than those transported for 5 h. Stocking density did not affect blood parameters studied. Transport time significantly affected some carcass quality parameters, but stocking density had no significant effect. Suckling lambs transported for 5 h had lower liver weights and dressing percentages than those transported for 30 min. Transport time influenced pH values, with lambs subjected to the longer journey showing the lowest pH at 0 h in the three muscles studied, with the lowest final pH in L and PM. The PM lambs transported at high density (0.12 m2/lamb) had the lowest pH at 24 h. Transport time and stocking density did not greatly affect colour and texture parameters. The meat from lambs transported for 30 min had higher WHC than meat from lambs transported for 5 h. Animals transported for longer journeys showed higher lipid oxidation after 5 days of ageing than those transported for 30 min. Loading and initial transport caused significant stress response in suckling lambs, that stress response was reduced over the time course of the journey.