Factorial calculation of nutrient requirements in lactating queens

Abstract

The energy, protein, calcium and phosphorus requirements of lactating queens were estimated by using the factorial method. Requirement values for protein and energy were divided into requirements for maintenance and for milk production. For maintenance, existing data were used. For milk production, the net requirements were calculated by summing the energy and protein losses in milk; the gross requirements were then estimated taking into account the utilization of metabolizable energy (ME) for milk production and the digestibility of protein and its utilization for milk production. Net maintenance requirements for calcium and phosphorus were calculated from the endogenous fecal, renal and cutaneous losses. Losses in milk were added. For calculation of gross calcium and phosphorus requirements, utilization was estimated from true digestibility under suboptimal, but not extreme conditions. For queens with large litters at the peak of lactation, the following estimated requirements were derived (per kg body weight): 0.81 MJ ME, 14 g protein, 428 mg calcium and 303 mg phosphorus.