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Pesquisa Veterinária Brasileira, 2013

Pesq. Vet. Bras. 33(6):826-830, junho 2013 826 RESUMO.-[Efeito da modificação ambiental sobre a o... more Pesq. Vet. Bras. 33(6):826-830, junho 2013 826 RESUMO.-[Efeito da modificação ambiental sobre a ocorrência de mastite e alterações hormonais de vacas Holandesas.] O trabalho teve como objetivo avaliar a eficiência do sistema de resfriamento adiabático evaporativo, acionado em diferentes horários, em instalação do tipo fre-ABSTRACT.-Arcaro J.R.P., Matarazzo S.V., Pozzi C.R., Arcaro Junior I., Toledo L.M., Costa E.O. & Miranda M.S. 2013. Effects of environmental modification on mastitis occurrence and hormonal changes in Holstein cows. Pesquisa Veterinária Brasileira 33 :826-830. The purpose of this research was to evaluate the effects of evaporative cooling in freestall on mastitis occurrence, milk production, and composition, as well as cortisol, T 3 (triiodothyronine), and T 4 (thyroxin) levels in lactating dairy cows. Twenty-eight multiparous cows averaging 70 ± 10 day postpartum were used in four treatments from January to March 2003. The treatments were: Day (cooling from 7:00 a.m. to 7:00 p.m.); Night (cooling from 7:00 p.m. to 7:00 a.m.); 24-hour (cooling 24-hour); and Control (no cooling). Wired cup test was used for clinical mastitis diagnosis, and the California Mastitis Test (CMT) was used to identify subclinical mastitis. Blood and milk samples were taken weekly for microbiological and hormonal analyses. The cortisol levels were higher than normal values in all treatment groups, suggesting stress conditions, but T 3 and T 4 levels remained normal in all groups. The occurrence of subclinical mastitis was lower in Day and Night groups than in Control and 24-hour groups. Regarding the microbiological analyses, in all groups the isolation of Corynebacterium sp. from milk samples increased while negative coagulase staphylococci (CNS) declined as etiological agents of subclinical mastitis. However, in Day and 24-hour groups, coagulase positive staphylococci (CPS) increased mainly Staphylococcus aureus (49.8% and 47.7% respectively). The Night group showed a decrease in subclinical mastitis occurrences. Our data indicate that all animals subjected to treatments presented high levels of cortisol, indicating a stress condition. The Night treatment presented a reduction in microbial isolation, suggesting a reduced susceptibility to mastitis.

Pesquisa Veterinária Brasileira, 2013

Pesq. Vet. Bras. 33(6):826-830, junho 2013 826 RESUMO.-[Efeito da modificação ambiental sobre a o... more Pesq. Vet. Bras. 33(6):826-830, junho 2013 826 RESUMO.-[Efeito da modificação ambiental sobre a ocorrência de mastite e alterações hormonais de vacas Holandesas.] O trabalho teve como objetivo avaliar a eficiência do sistema de resfriamento adiabático evaporativo, acionado em diferentes horários, em instalação do tipo fre-ABSTRACT.-Arcaro J.R.P., Matarazzo S.V., Pozzi C.R., Arcaro Junior I., Toledo L.M., Costa E.O. & Miranda M.S. 2013. Effects of environmental modification on mastitis occurrence and hormonal changes in Holstein cows. Pesquisa Veterinária Brasileira 33 :826-830. The purpose of this research was to evaluate the effects of evaporative cooling in freestall on mastitis occurrence, milk production, and composition, as well as cortisol, T 3 (triiodothyronine), and T 4 (thyroxin) levels in lactating dairy cows. Twenty-eight multiparous cows averaging 70 ± 10 day postpartum were used in four treatments from January to March 2003. The treatments were: Day (cooling from 7:00 a.m. to 7:00 p.m.); Night (cooling from 7:00 p.m. to 7:00 a.m.); 24-hour (cooling 24-hour); and Control (no cooling). Wired cup test was used for clinical mastitis diagnosis, and the California Mastitis Test (CMT) was used to identify subclinical mastitis. Blood and milk samples were taken weekly for microbiological and hormonal analyses. The cortisol levels were higher than normal values in all treatment groups, suggesting stress conditions, but T 3 and T 4 levels remained normal in all groups. The occurrence of subclinical mastitis was lower in Day and Night groups than in Control and 24-hour groups. Regarding the microbiological analyses, in all groups the isolation of Corynebacterium sp. from milk samples increased while negative coagulase staphylococci (CNS) declined as etiological agents of subclinical mastitis. However, in Day and 24-hour groups, coagulase positive staphylococci (CPS) increased mainly Staphylococcus aureus (49.8% and 47.7% respectively). The Night group showed a decrease in subclinical mastitis occurrences. Our data indicate that all animals subjected to treatments presented high levels of cortisol, indicating a stress condition. The Night treatment presented a reduction in microbial isolation, suggesting a reduced susceptibility to mastitis.