2.4. Sample size and sampling
The minimum sample size (n) required was determined according to Thrusfield (2007) using 95% level of confidence, the prevalence of 66.1% (Adelakun and Akande, 2018) and desired absolute precision of 5%. i.e. n = Z2 p (1-p)/d2 = 345 cattle. However, 377 cattle were examined to increase precision.
Cattle were selected randomly from 39 different herds across the two LGAs, the herds were grouped into three; 0-30, 31-50 and >50 based on the herd size. The average number of cattle per herd is 48, an average of 20% of each herd was sampled. The maximum herd size screened was 89 while the least sampled was 29.