Losses in milk yield, fat and protein contents according to different levels of somatic cell count in dairy goats

To estimate the losses in milk yield, fat content and protein content according to different levels of somatic cell count (SCC), and to evaluate the influence of some variation factors on SCC in Saanen, Alpine and Nubian U.S. goats, data obtained from twelve dairy goat farms and seven different breeds for the period 2003-2010 were used. Individual milk yield was measured monthly during lactation. Somatic cell count, fat (%F) and protein (%P) contents were determined using automated equipment. SCC was transformed to a log scale (SCS). In a first analysis, the fix effects ANOVA procedure was used to evaluate the influence of different variation factors on SCS. In an additional analysis and using only first lactation data, losses in test day milk yield and test day %F and %P according to the SCS recoded level, were estimated for Alpine, Nubian and Saanen breeds. Effects of test day milk yield level (MY), %F level, %P level, flock, breed, year and season of kidding, lactation number, litter size, length of dry period, lactation days at each sampling as covariate, significantly influenced SCS (P < 0.01). The estimated losses in test day milk yield according to the recoded level of SCS used for Alpine, Nubian and Saanen breeds were 0.5-12.9%, 0.4-29.1% and 0.2-15.4%, respectively. For %F loss estimated for Alpine, Nubian and Saanen goats these were 0.01-10.8%, 0.5-7.6% and 1.1-16.0%, respectively. Estimated losses in %P for the same breeds were from 0.30% to 7.8%, 0.5% to 7.2% and 2.0% to 15.0%, respectively. Results suggest the need for the establishment of prevention and control programs of subclinical mastitis based on SCS routine monitoring in commercial goat herds.