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Periódicos Brasileiros em Medicina Veterinária e Zootecnia

Physiological and pathological alterations in the mammary gland of Holstein cows during transition period

Ramos, Jean SilvaMadureira, Karina MediciBaldacim, Vinicius Alvim PassosSilva, Cynthia Pereira da Costa eDias, Mailson Rennan BorgesStricagnolo, Cláudia ReginaGomes, Viviani

Background: Physiological and immunological adaptations occurred in peripartum period may be responsible for susceptibility to intramammary infections during colostrogenesis. Increase in blood flow and hormones cause physiological edema by accumulation of lymphatic fluid in interstitial space. Specific composition of mammary secretion increases the susceptibility to mastitis. So, the study of physical, cellular and microbiological changes in the mammary gland in this period are fundamental for understanding, diagnosing and adopting prophylactic measures for bovine mastitis. This study aimed to characterize physiological and pathological changes that occur in the mammary gland during transition period. Materials, Methods & Results: Thirteen cows, in second to fourth lactation were followed from 3 weeks pre-calving to 3 weeks post-calving. Cows were submitted weekly to physical examination of mammary gland, strip cup test, California Mastitis Test (CMT), Microscopic Somatic Cell Count (MSCC), and bacteriological examination of mammary secretion. Mammary quarters were divided into two groups: BAC-: samples that did not present bacteriological growth throughout transition period; BAC+: samples that presented bacteriological growth in at least two isolates of the same bacterial genus. Regarding physical examination of mammary gland, the parameters localized or generalized alteration in volume, asymmetry, reddish color, reduced skin elasticity, increased temperature, and swollen consistency presented higher frequencies in the BAC- group. On the other hand, infection in mammary quarters of cows from BAC+ group promoted a decrease in frequencies of increased volume, decreased elasticity, and elevated temperature in the mammary gland, in addition to a higher positivity to CMT and higher cellularity. Overall rate of intramammary...(AU)

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