Physiological response to heat stress and ingestive behavior of lactating Jersey cows in silvopasture and conventional pasture grazing systems in a Brazilian subtropical climate zone.

The aim of this study was to evaluate the physiological response to heat stress and ingestive behavior of Jersey cows in silvopasture and conventional pasture grazing systems. The experiment was carried out during the warm season, spanning spring, summer, and fall seasons in the Brazilian subtropical climate zone. Twelve lactating Jersey cows were observed in rotational grazing on Cynodon nlemfuensis Vanderyst and Panicum maximum Jacq. Treatments were composed of different grazing systems (silvopasture and conventional pasture). The silvopasture grazing system had eucalyptus trees (Eucalyptus grandis Hill ex Maiden) with an average height of ≈ 10 m and row spacing of 20 m. In the conventional pasture grazing system, there were no rows of eucalyptus and no other type of tree or structure to provide shade to the animals. During the summer and fall periods of evaluation, the silvopasture animals presented a lower respiratory rate, whereas during the spring and fall evaluation periods, these animals presented a lower rectal temperature. Cattle in the silvopasture showed longer grazing times at night (+21.65 min) and overall (+36.00 min) and remained lying down (ruminating and resting) for longer (+ 73.07 min) than conventional pasture grazing system animals. In addition, the animals in the silvopasture had a lower water intake (3.12 L/100 kg BW). The silvopasture grazing system improved the welfare of the grazing Jersey cows, as evidenced by the improvement in physiological response to heat stress, increased grazing time and decreased standing time (resting + ruminanting) when compared to cows in the conventional pasture grazing system.

Avaliação dos efeitos do flunixim meglumine sobre a concentração sérica de progesterona e ciclo estral em novilhas e vacas mestiças / Assessment on the effects of flunixin meglumine on the serum concentration of progesterone and the estrous cycle in crossbred heifers and cows

Baseando-se nos mecanismos de interrupção da síntese de PGF2a em bovinos, objetivou-se com este estudo avaliar os efeitos do flunixin meglumine (FM) sobre o comprimento do ciclo estral e sobre os níveis de progesterona, em novilhas e vacas mestiças. Após sincronização dos estros, os animais foram divididos em grupos: controle (cinco vacas e quatro novilhas) e tratado (seis vacas e seis novilhas), sendo submetidos à colheita diária de sangue, até o estro subseqüente. Do 13o ao 18o dia, aplicou-se nos animais do grupo tratado 1,65 mg/kg intramuscular de FM, e nos do grupo controle, mesmo volume de solução fisiológica. A determinação da concentração sérica de progesterona foi realizada por RIA. Os resultados do comprimento do ciclo estral foram comparados entre os grupos e entre animais, pelo teste t de Student, enquanto a concentração de progesterona foi normalizada em relação à luteólise, e analisada entre os grupos pelo teste t de Tukey (SAS). Não se observou diferença (P>0,05) no comprimento do ciclo estral entre grupos e entre novilhas e vacas, tratadas e não tratadas. O dia do ciclo estral em relação à concentração de progesterona máxima e inferior a 1,0ng/mL, e a concentração sérica de progesterona entre os animais do grupo controle e tratado, também foram semelhantes entre os grupos (P>0,05). No entanto, observou-se diferença (P<0,05) na curva que evidencia a queda da progesterona em relação ao momento da luteólise entre os animais dos grupos experimentais. Conclui-se que, embora se tenha observado efeito do tratamento, como descrito acima, sua ação seria mais bem caracterizada se a população amostral tivesse sido maior.

This paper reports results from the assessment on the effects of flunixin meglumine (FM) on the estrous cycle and serum levels of progesterone in crossbred cows and heifers. After the estrous synchronization, the animals were separated into two groups: control (5 cows and 4 heifers), and experimental (6 cows and 6 heifers). They were submitted to daily blood sampling until the next estrus. From the 13th to the 18th day of the estrous cycle, each animal from the experimental group received 1.65 mg/kg of FM by intramuscular route, while animals from the control group received equal volumes of sterile saline. Levels of progesterone were measured by radio-immune-assay. The length of estrous cycle was compared among groups and individuals by Student’s t-test, whereas the levels of progesterone were analyzed by Tukey’s t-test. There was no significant difference in the estrous cycle length among groups and individuals. The estrous cycle day, in relation to the concentration of progesterone – highest and lower to 1.0 ng/ml, and the seric concentration of progesterone among animals from both control and experimental groups were also similar (P>0.05). However, there was no difference concerning the concentration of progesterone decrease among theexperimental groups. It was concluded that, under the conditions this study was carried out, even though the effect of the treatment was observed, its action would be better characterized if the sample population were bigger.