Concentrações plasmáticas de testosterona, triiodotironina (T3) e tiroxina (T4) em bodes submetidos ao estresse calórico Plasma concentrations of testosterone, triiodothyronine (T3), and thyroxine (T4) in bucks submitted to heat stress

Para verificar o efeito do estresse calórico (EC) nas concentrações plasmáticas de testosterona, triiodotironina (T3) e tiroxina (T4), oito bodes, das raças Saanen (n=4) e Alpina (n=4), foram mantidos em câmara bioclimática, sob condições de termoneutralidade (13,0ºC a 26,7ºC) durante 30 dias e, após um período (60 dias) de descanso, submetidos ao EC (23,7ºC a 34,0ºC) por 30 dias. Para minimizar as variações sazonais nos perfis hormonais devido ao fotoperíodo, durante toda fase experimental, incluindo a de adaptação em condições de termoneutralidade (30 dias), o fotoperíodo foi controlado utilizando-se alternância de dias longos (16h de luz e 8h de escuro) e de dias curtos (8h de luz e 16h de escuro) a cada 30 dias. As amostras de sangue foram coletadas duas vezes por semana durante cinco semanas. No conjunto das raças, o EC não influenciou (P>0,05) as concentrações de testosterona (1,8±0,2 vs 1,3±0,2ng/ml) e nem a de T4 (52,7±2,8 vs 50,0±2,8ng/ml). Houve declínio (P<0,01) das concentrações de T3 nos animais submetidos ao experimento (1,3±0,1 vs 1,0±0,1ng/ml), mas a redução foi observada somente nos bodes Saanen. Em ambas as raças, as concentrações de T3 e T4 variaram (P<0,01) conforme o dia da coleta das amostras de sangue. O EC foi suficiente para produzir uma resposta fisiológica com redução das concentrações plasmáticas de T3 em bodes das raças Saanen, mas não da raça Alpina, assim como não foi capaz de alterar os níveis plasmáticos de testosterona e nem de T4.<br>To verify the effect of heat stress (HS) on plasma testosterone, triiodothyronine (T3), and thyroxine (T4) concentrations, eight Saanen (n=4) and Alpine Brown (n=4) bucks were kept in climate chamber under thermal neutral conditions (13.0ºC to 26.7ºC) for 30 days. After a resting period (60 days), the same bucks were submitted to heat stress (23.7ºC to 34.0ºC) for another 30 days. To neutralize the seasonal variations of hormonal profiles throughout the period, the photoperiod was controlled every 30 days altering long (16 hours of light and 8 hours of darkness) and short days (8 hours of light and 16 hours of darkness). The blood samples were collected twice a week during five weeks. In both breeds, there was no effect of HS (P>0.05) on plasma concentrations of testosterone (1.8±0.2 vs 1.3±0.2ng/ml) and T4 (52.7±2.8 vs 50.0±2.8ng/ml). There was a decline (P<0.01) of plasma T3 concentrations (1.3±0.1 vs 1.0±0.1ng/ml) after HS treatment, but this reduction was only evident in Saanen bucks. In both breeds, the plasma concentrations of T3 and T4 varied (P<0.01) according to the day of blood sample collection. The HS was sufficient to provoke a physiological response with reduction of plasma concentrations of thyroid hormones mainly of T3 in Saanen bucks, but not in Alpine ones. The HS did not affect the plasma testosterone and T4 levels

Records of performance and sanitary status from a dairy cattle herd in southern Brazil

Over the last decades, the emphasis on the health of dairy cows has changed from an individual to a herd level. In this scenario, the role played by the recording system and its interpretation by veterinarians has gained primordial importance. The records of productive and reproductive performance and of sanitary status from a southern Brazilian dairy cattle herd have been presented and discussed. The period of study was 2000-2009. Mean values per lactation period were 349D 8436M 290F 275P 201SCS (D: days in lactation, M: kg of milk yield, F: kg of fat, P: kg of protein and SCS: somatic cell score in 1000 cells/ml of milk). Major indexes of reproductive efficiency included age at first calving (31 months), services per conception (2.1), intercalving interval (428 days), calving to conception interval (146 days), mean annual rates of parturitions (76.2%), fetal losses (9.8-19.0%), and stillbirths (3.6%), apart of voluntary waiting period (94 days). Main information on sanitary status of the herd was associated with the mean prevalence of common disorders of dairy cattle such as anaplasmosis (29.8%), mastitis (27.8%), digital diseases (26.3%), ovarian cysts (21.3%), placental retention (19.7%), postpartum uterine infections (10.6%), and calf diarrhea (23.7%) and pneumonia (16.8%), among others. In addition, culling reasons (low reproductive performance [56.3%] and udder/mastitis problems [33.6%]), causes of cattle deaths (anaplasmosis [16.4%] and leukosis [11.4]), and the impact of cattle diseases such as tuberculosis, leukosis, and neosporosis on the herd have also been presented and succinctly discussed. Numbers between brackets represent rates accumulated in the 10-year period