ABSTRACT
Descreve-se uma nova metodologia para medir o temperamento dos bovinos por meio da reatividade, obtida por um dispositivo eletrônico que quantifica o número e a intensidade dos movimentos do animal em ambiente de contenção móvel, numa escala de 1 a 9.999 pontos. A reatividade foi comparada a características determinadas por outros dois métodos tradicionais para quantificar o temperamento bovino: a velocidade de fuga e o escore de temperamento. Foram utilizados 610 bovinos da raça Nelore, com média de idade de 467 dias e provenientes de dois rebanhos. As observações da reatividade não se ajustaram às distribuições normal, Poisson e binomial negativa. A padronização e as transformações logarítmicas neperianas e na base 10 não foram eficientes para adequar os dados à distribuição normal. Os animais avaliados para a característica apresentaram grande variabilidade fenotípica, com reatividade média de 534±447 pontos na escala original, mediana 442 pontos, moda 372 pontos, variação de 1 a 2.218 pontos e coeficiente de variação de 84 por cento. A correlação de classificação de resíduos encontrada entre reatividade e escore de temperamento variou de 0,75 a 0,85 (P<0,001) e foi superior em valores absolutos às correlações entre reatividade e velocidade de fuga e entre velocidade de fuga e escore de temperamento. A nova metodologia é eficiente para quantificar o temperamento de animais da raça Nelore e possui vantagens em relação às características velocidade de fuga e escore de temperamento. A obtenção da reatividade animal é rápida, prática, objetiva e segura para quem a faz, além de apresentar grande variabilidade fenotípica.
This paper describes a new methodology to access bovine temperament using it's reactivity eletronically measured as the intensity and count of movements in a mobile cage, using a scale from 1 to 9,999 points. The new trait, reactivity, was compared to two other traditional methods, flying speed and temperament scores. Six hundred and ten contemporary Nellores, with average age of 467 days and from two herds were used. Reactivity data did not fit Normal nor Poisson nor Negative Binomial Distibutions. Standartized reactivity data, neperian and base 10 log reactivity transformations were not successful in adjusting data to normal distribution. Reactivity presented large phenotipic variation, with average in the original scale of 534±447 points, median of 442, mode 372, range from 1 to 2,218 points and variation coefficient of 84 percent. Residual rank correlation between reactivity and temperament score vary from .75 to .85 (P<.001), and were larger than the ones between reactivity and flight speed and between flight speed and temperament score. The new methodology is efficient in measuring temperament of Nellore cattle and it has advantages in relation to the traits flight speed and temperament score. The measure of reactivity is easy, fast to get and safe to record. In addition, this trait presents large variability.
Subject(s)
Animals , Cattle , Behavior, Animal/physiology , Risk Measurement Equipment , Reactivity-Stability , Temperament/classificationABSTRACT
Diets rich in saturated fatty acids are one of the most important causes of atherosclerosis in men, and have been replaced with diets rich in unsaturated fatty acids (UFA) for the prevention of this disorder. However, the effect of UFA on myocardial performance, metabolism and morphology has not been completely characterized. The objective of the present investigation was to evaluate the effects of a UFA-rich diet on cardiac muscle function, oxidative stress, and morphology. Sixty-day-old male Wistar rats were fed a control (N = 8) or a UFA-rich diet (N = 8) for 60 days. Myocardial performance was studied in isolated papillary muscle by isometric and isotonic contractions under basal conditions after calcium chloride (5.2 mM) and ß-adrenergic stimulation with 1.0 æM isoproterenol. Fragments of the left ventricle free wall were used to study oxidative stress and were analyzed by light microscopy, and the myocardial ultrastructure was examined in left ventricle papillary muscle. After 60 days the UFA-rich diet did not change myocardial function. However, it caused high lipid hydroperoxide (176 ± 5 vs 158 ± 5, P < 0.0005) and low catalase (7 ± 1 vs 9 ± 1, P < 0.005) and superoxide-dismutase (18 ± 2 vs 27 ± 5, P < 0.005) levels, and discrete morphological changes in UFA-rich diet hearts such as lipid deposits and mitochondrial membrane alterations compared to control rats. These data show that a UFA-rich diet caused myocardial oxidative stress and mild structural alterations, but did not change mechanical function.