Differences in body temperature between black-and-white and red-and-white Holstein cows reared on a hot climate using infrared thermography.

Heat stress is one of the greatest issues of the dairy industry in regions with hot climate. Since coat color appears to be related to heat stress adaptiveness, we compared rectal temperatures and surface temperatures of Red-and-white (RW, n = 14) and Black-and-white (BW, n = 16) Holstein cows using infrared thermography in both cold (July; mean temperature: 15.5 °C) and hot (March; mean temperature: 30.5 °C) seasons in Southern Brazil. Thermographic images were taken from the left side of the animal at a distance of 4 m. The images obtained were then analyzed using the software Testo IRSoft. The variables obtained by thermography of the body surface include the temperature of non-pigmented patches, obtained using the average of five spots on white patches in a rectangle drawn on the body of the cow from the scapula to the ilium of the cow until the middle of the ribs; the temperature of pigmented patches, obtained using an average of 5 pigmented spots on the same rectangle; the temperature at the hottest spot and the temperature at the coldest spot, within the same rectangle. Rectal temperature measures were taken by a mercury thermometer during milkings. In our findings, during the cold season, RW cows had lower temperatures on the surface of pigmented spots (p = 0.01) but did not differ from BW animals when comparing rectal temperatures (p = 0.70). During the hot season, however, RW cows had lower temperatures on white spots (p = 0.049) as well as lower rectal temperatures (p = 0.029). These results suggest that the red coat phenotype presents less absorption of solar radiation, retaining less heat.

[Schistosomiasis--infection and race of carriers]. / Esquistossomose--infecção e raça dos portadores.

The geometric average (parasitical charge) of the eggs of Schistosoma mansoni quantified by Kato-Katz method in five parasitological fecal exams of 868 individuals, was correlated to sex, age and racial groups. The higher averages were observed in females from 6 to 15 years old and in black individuals--the analysis of variation showed, however, more significant effect of age and of sex. However, when the average results were translated, qualitatively into positives and negatives no sexual differences were observed and only the individuals under 5 years old were significantly more negative than those over 6 years old. Nevertheless, in these age brackets the white individuals were mostly negative, and in the sample group they reach statistic significance (X2(2) = 20.76 p 0.0001)--with the following percentage of negatives: whites--26.8%; mulatos--16.3% and negroes--9.1%. These results reinforce the hypothesis, among other predisponent factors of Schistosomiasis--infection, of the effect of the social-economical level in the Brazilian black population.