Relación entre recuento celular, producción lechera, contenidos graso y proteico de la leche e ingresos económicos por leche en la cabra Murciano-Granadina

Abstract

To study the relationship between somatic cell count (SCC), milk yieldand contents, as well as their effect on milk incomes per goat andday, between 2009 and 2014, 758,382 monthly test-day records wereobtained from 65,056 Murciano-Granadina goats in 132 Spanish dairyflocks. Variables measured were SCC, milk yield and fat and proteinpercentages; means were 5.78 log10 cells/mL, 2.04 kg/day, 5.37% and3.67%, respectively. Significant effects of year, herd test date, season,parity, month of lactation, litter size and covariables milk yield, fat andprotein contents were evidenced on SCC. The regression slopes werenegative for milk yield and positive for fat and protein content, thuspointing out that high SCC in milk were associated with low milk yield andhigh contents. A second ANOVA was built to evaluate the evolution of testdayvariables as SCC level increased within lactation. The percentagesestimated in losses of test day mil yield for SCC levels 1000×103 cells/mL,2000×103cells/mL, 3000×103 cells/mL and >7000×103 cells/mL were11.4%, 19.5%, 24.2% and 35.7%, respectively. Milk contents gains werealso quantified. Milk incomes per goat and day (according to currentpayment system) revealed important economic losses (from 9.5% to31.6%) for above-mentioned SCC levels. Results emphasize the needfor the establishment of prevention and control programs of subclinicalmastitis based on SCC in dairy goats, as well as the appropriateness oftest day recording scheme for this purpose.