Table 8 Estimated incidence of clinical mastitis (cases per 100 cows per lactation) in Ireland during 2010, using three different scenarios (with differing numbers of tubes per treatment regime) and based on DCT sales collated by GfK Kynetec
From: Insights into udder health and intramammary antibiotic usage on Irish dairy farms during 2003-2010
| Â | Â | Â | Explanation, assumptions |
|---|---|---|---|
i. | Approximate number of dairy cows (2010) | 1,000,000 | Includes all milking cows, assuming an average 5 lactations/cow |
ii. | Number of cows at risk of clinical mastitis | 1,000,000 | Equals i. (all lactating cows are at risk of clinical mastitis) |
iii. | Days at risk per cow | 335 | Assumes 305 day lactation, 60 day dry period and cows are at risk from 30 days prior to calving until drying offa |
iv. | Days after treatment before a subsequent treatment is considered a new case | 8 | As recommendeda |
v. | Number of in-lactation tubes sold (2010) | 1,664,066 | As collated by GfK Kynetec |
vi. | Total number of in-lactation tubes sold | 1,957,725 | Assuming v. represents 85% of all DCT sales |
Scenario 1: 3 tubes per treatment regime | |||
1.i | Total number of treated clinical cases | 652,575 | Assuming 3 tubes per treatment regime, one affected quarter per cow, tubes restricted to clinical cases only |
1.ii | Total number of new cases | 652,575 | 100% of treated cases considered new cases |
1.iii | Number of clinical cases per 100 cow-years at risk | 72.4b, c | Â |
Scenario 2: 4 tubes per treatment regime | |||
2.i | Total number of treated clinical cases | 489,431 | Assuming 4 tubes per treatment regime, one affected quarter per cow, tubes restricted to clinical cases only |
2.ii | Total number of new cases | 489,431 | 100% of treated cases considered new cases |
2.iii | Number of clinical cases per 100 cow-years at risk | 54.0b, c | Â |
Scenario 3: 5 tubes per treatment regime | |||
3.i | Total number of treated clinical cases | 391,545 | Assuming 5 tubes per treatment regime, one affected quarter per cow, tubes restricted to clinical cases only |
3.ii | Total number of new cases | 391,545 | 100% of treated cases considered new cases |
3.iii | Number of clinical cases per 100 cow-years at risk | 43.1b, c | Â |