ABSTRACT
This study was carried out to investigate differences in milk composition and production when followed the stages of lactation, parities and subclinical mastitis. The mammary quarters of cows were arranged in agreement to days in milk and parities: Group "A" (lactating cows until 2 months after parturition and until the fifth lactation); Group "B" (lactating cows until 2 months after parturition and after fifth lactation); Group "C" (animals in intermediary months of lactation stage and until the fifth lactation); Group"D" (animals in intermediary months of lactation stage and after fifth lactation); Group "E" (cows in corresponding period of 2 months before the end of lactation and until the fifth lactation); Group "F" (lactating cows within 2 months before the end of lactation and after fifth lactation). The milk characteristics studied were the milk production, somatic cell count (SCC), chloride levels, titratable acidity, density, non-fat solids and cryoscopy. The lactation stage and the parities changed the milk production and chloride levels and these factors should be considered when the influence of subclinical mastitis upon the milk composition and milk production is analyzed. The days in milk and the parities of lactating cows should be investigated in addition to the infective etiology of subclinical mastitis because variations of the effects can occur in agreement to the microorganisms.
KEY WORDS
Milk; subclinical mastitis; stage of lactation; parity