Protein and energy requirements of veal calves : estimation and variation factors

Abstract

Little knowledge on the nutritional requirements of veal calves has been acquired since the recommendations of Toullec (1988). Most of the studies used for these recommendations were conducted between the nineteen-sixties and nineteen-eighties, and requirements were expressed as apparently digested proteins and metabolisable energy related to calf body weight, feed intake and body weight gain. Studies conducted later have confirmed these recommendations. However, some points have to be modulated. The efficiency of retention of diges-ted protein cannot be considered as a constant parameter (especially for heavy calves) but rather as a decreasing function of the calf’s age or body weight. Separate estimation of both protein and energy requirements would allow the establishment of a synthetic criterion such as the ratio between apparently digested proteins and metabolisable energy. This criterion is rarely used, especially for animals heavier than 150 kg. Moreover, genotypes have evolved (and are still evolving) and new production techniques such as roughage feeding and group-housing are still being developed. These aspects suggest that the updating of the scientific information on nutrient requirements and utilisation in veal calves is necessary in order to propose new recommendations.