Table 3.
Significant (p < 0.05) univariable over-dispersed Poisson regression analyses for continuous explanatory variables on farm and flock, lambing, health and feeding management associated with incidence rate of clinical mastitis.
| Variable | N | RR | Lower CI | Upper CI | |
|---|---|---|---|---|---|
| Percentage of flock with mastitis in previous year kept for breeding in 2009 | 260 | 1.62 | 1.26 | 2.08 | |
| Percentage of flock with poor udder conformation | 173 | 1.13 | 1.08 | 1.18 | |
| Percentage of flock ‘too fat’ versus ‘about right’ | At tupping | 293 | 1.01 | 1.00 | 1.01 |
| Mid pregnancy | 270 | 1.01 | 1.00 | 1.02 | |
| Mid lambing | 285 | 1.01 | 1.00 | 1.02 | |
| Percentage of flock with singles at scanning | 128 | 0.98 | 0.97 | 0.99 | |
| The percentage of flock with twins at scanning | 129 | 0.99 | 0.98 | 1.01 | |
| The percentage of flock with triplets at scanning | 127 | 1.04 | 1.02 | 1.06 | |
| The percentage of flock with poor udder conformation of the respondents that checked the mammary gland of ewes at lambing | 247 | 1.05 | 1.01 | 1.10 | |
| The number of lambs reared per ewe | 271 | 0.95 | 0.74 | 1.23 | |
| Percentage of lambs finished before weaning | 294 | 1.00 | 1.00 | 1.01 | |
| Percentage of flock with mastitis kept to breed | 288 | 1.62 | 1.26 | 2.08 | |
| Percentage of flock with poor udder conformation | 173 | 1.13 | 1.08 | 1.18 | |
| Age of oldest lambs at turnout (days) | 233 | 1.01 | 1.00 | 1.01 | |
N = number of respondents who gave a valid response to the question. RR = risk ratio. Lower and upper CI = 96% confidence intervals for the risk ratio.