The proposed reduction in the upper limit of somatic cell counts in raw milk and its effect on the milk industry in Puerto Rico

Abstract

Data from 302,995 test day records of individual cows of the Puerto Rico Dairy Herd Improvement Program (PRDHIP) and from 8,833 bulk tank results from all herds in Puerto Rico during the years 2004 and 2005 were analyzed for determining the potential effect of implementation of the National Mastitis Council's (NMC) proposal to reduce the present regulatory upper limit for somatic cell count of 750,000 cells/ml of crude milk. Means of herd test day milk yield per cow and of somatic cell scores on the linear scale for this data set were 17.2 kg and 3.9, respectively. On the basis of PRDHIP data, it was estimated that 20% of individual test day values, equivalent to 920,290 kg of raw milk, would exceed the upper limit if it were established at 600,000 cells/ml. The months of highest average milk production were February, March and May (18.4,18.2 and 18.2 kg/day, respectively).The lowest production was observed in August, September and October (16.3,15.6 and 15.8 kg/day, respectively). The months with the lowest average somatic cell score were February and April (both at 3.5) and those of the highest were August, September and October (4.2,4.2 and 4.3, respectively). The average somatic cell counts for herds enrolled or not enrolled in DHIP were similar (461,656 and 473,096, respectively; P greater than 0.05).