End of project report The effect of various space allowances on pituitary, adrenal, immune responses and performance was investigated in 72 Holstein x Friesian bulls. Bulls (403 ± 3.5 kg) were blocked by weight and randomly assigned into two groups (familiar, F and unfamiliar, UF) x three (1.2, 2.7 and 4.2 m2 per bull; n = 24 bulls per space allowance) treatments and housed for 83 days in 18 pens (n = 4 per pen). Blood samples were collected on day –1, 0, 3, 14, 36 and 77 with respect to mixing and housing on day 0. The bulls were administered with adrenocorticotrophic hormone (ACTH) on day 3 and corticotrophin-releasing hormone (CRH) on days 14, 36 and 77. The basal cortisol concentrations were not affected (P>0.05) by mixing of familiar and unfamiliar bulls. On day 3, basal cortisol was greater (P<0.05) in the bulls housed at 1.2 than those at 2.7 and 4.2 m2 space allowances while no effect was observed in ACTH-induced plasma cortisol concentration among treatments. Following CRH administration there was no effect (P>0.05) of treatment and treatment x time on ACTH. On day 14, interferon-? production was lower (P<0.05) in the bulls housed at 4.2 vs 2.7 m2 and was intermediate but not (P>0.05) different for those housed at 1.2 m2. Bulls housed at either space allowances had (P<0.05) neutrophilia, lymphopenia, eosinopenia and decreased haemoglobin on day 3 compared with day 0. The liveweight gain from days 0 to 83 was lower (P< 0.05) in bulls housed at 1.2 compared with those at 2.7 and 4.2 m2. Housing bulls at 1.2 m2 space allowance had a detrimental effect on their growth and was associated with an acute rise in plasma cortisol concentration (on day 3) compared with space allowances of 2.7 and 4.2 m2/bull. European Union Structural Funds (EAGGF)
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