Feeding and nutrition management of heatstressed\ud dairy ruminants

摘要

Climate change, with a constant increase in the Earth temperature, negatively affects livestock\udproduction and health. This paper will focus on the possible nutritional and feeding strategies to\udmitigate the negative impact of heat stress (HS) on ruminants. The first nutrient interacting with\udhot weather conditions is fibre and its digestibility. It is well recognised how fibre may affect voluntary\uddry matter intake (DMI), chewing and ruminating activity. A possible dietary strategy to\udcounteract the reduced DMI under hot environment is represented by the increased diet energy\udconcentration, protein supply and essential aminoacids. Mineral feeding under HS condition\udmust cover the supply of each nutrient as consequence of altered turnover, and the needs\udrelated to buffer requirements. Particular interest is growing in the use of Se (Se-yeast), because\udof its role to support the animal antioxidative defences. Water is a pivotal nutrient to cope with\udHS in ruminants because it plays a role in animal thermoregulation. Recently, some vitamins and\udfeed additives were studied for their action on the animal physiology to cope with HS. Among\udvitamins, niacin was tested for its action on the vasodilatation in the mammalian and for its role\udin lipid metabolism; among feed additives, yeasts and plant extracts may exert a positive action\udin rumen metabolism as well as in regulation of body temperature.