Systems stunning with CO2 gas on Manchego light lambs: Physiologic responses and stunning effectiveness

Effect of four stunning treatments using different CO2 concentrations and exposure times (G1: 80%90 s; G2: 90%90 s; G3: 90%60 s; G4: 80%60 s) on hormonal, haematological and biochemical parameters in Manchego breed light lambs and their stunning effectiveness (% animals correctly stunned) was studied. An electrically stunned control treatment (G5) was used. G1 showed the highest plasmatic hormonal, red cell distribution (RDW) and lactate levels. Haemoglobin, mean corpuscular volume (MCV), mean cell haemoglobin (HbCM), glucose, lactate deshydrogenase (LDH), sodium, potassium and creatine kinase (CK) were highest in G5. Stunning effectiveness was maximum (100%) in G3 and G5, only 50% in G1 and G2 and minimum (30%) in G4.A discriminant analysis showed a function for discriminating between G5 and the gas stunned groups, and another one for discriminating between gas stunned groups. Only potassium and adrenaline variables marked the difference among groups.