Behavioral and Haemato-Biochemical Responses of Nguni and Boran Steers Post Relocation and Herd Regrouping in a Novel Environment

Behavioural and blood-based physiological responses of Nguni (NG) and Boran (BR) steers, following relocation to a new environment and herd regrouping were examined. Ten steers of each genotype aged 9 months and reared under similar conditions were studied over 16 weeks: 1 for acclimatization and baseline measurements in original groups, 15 for post regrouping measurements. Each sampling week, direct visual observations and durations of aggressive and affiliative interactions were recorded between 0500-1900h for 3 conservative days. Blood samples were drawn fortnightly by jugular venipuncture for plasma cortisol, glucose, creatine kinase (CK) and haematological analysis. In weeks 1-5, BR had higher instances of head-butting (P=0.0311), mounts (P=0.0142) and threats (P=0.0241) compared to NG (P<0.0001, P=0.0412 and P=0.0241, respectively). However, these significantly declined from weeks 7-15 in both genotypes. Grooming increased consistently over the weeks in both genotypes (P=0.0214). Head-butting correlated with cortisol (r=-0.116), CK (r=-0.295) and neutrophil-to-lymphocyte ratio (r=-0.144). Grooming correlated (r=0.137) with white-blood-cell-count. Herd regrouping temporarily disrupted social behaviour, with BR showing more aggression towards NG steers. Nevertheless, the two genotypes established some stability within five weeks of social mixing.