THE ECONOMIC VALUE OF SOMATIC-CELL COUNT PAYMENT SCHEMES FOR UK DAIRY-CATTLE BREEDING PROGRAMS

Predicted transmitting abilities for somatic cell counts (SCC) are ava ilable in the United Kingdom and there is a direct economic benefit at tached to reducing SCC as the milk payment schemes include a penalty f or high SCC levels in bulk tank samples and sometimes a premium for lo w SCC. The aim of the present study was to establish the economic impo rtance of bulls' breeding values for SCC in relation to this payment s cheme for SCC. To do this, an empirical method was developed using 645 071 individual cow SCC and milk yield test-day records from 358 herds. The economic value teas calculated by (i) decreasing all individual c ow records by 0.01 and comparing the average penalty with the current average penalty, and (ii) taking the derivative of a Gompertz function describing the within-herd penalty per cow as a function of the avera ge within-herd 3-month rolling geometric mean SCC. Mean milk test-day yield and average test-day SCC were 20.4 kg and 262 kcount per ml resp ectively with, on average, 83 cows tested each day. In the current sit uation the average penalty paid was 0.54, 0.18 and 3.2 pence per litre depending on whether an England and Wales, Scottish or future payment scheme was used, respectively. Across the population, the economic va lues per 0.01 decrease in SCC were pound 1.04, pound 0.54 and pound 6. 03 per cow per year for these three payments schemes respectively. How ever these economic values depend strongly on the mean SCC. Herds have different means and as the future population mean is difficult to pre dict, it is suggested that for herds with the majority of their bulk t ank samples in penalty bands 1, 2 or 3+ (average SCC of <150, 150 to 2 50 and 250+) the economic values are pound 0, pound 0.50, and pound 15 per cow per year per 0.01 reduction in SCC, respectively, until addit ional benefits have been quantified.