Urinary energy losses in dogs fed commercial extruded foods.
Energy and nitrogen losses in the urine were recorded in 134 individual balances with adult (1- to 2-year-old) female Beagles that were fed 23 dry extruded dog foods ranging in crude protein (CP) content from 242 to 360 g/kg dry matter. The energy equivalent of urinary nitrogen was estimated as 33.9 kJ/g N. Both energy losses in the urine corrected for the nitrogen balance, and the metabolizable energy (MEn): digestible energy (DE) ratio were found to be closely related to diet CP content (r : 0.851 and 0.820). The MEn content of extruded dog foods can be accurately calculated from the DE content, either by subtracting 4.59 MJ/kg CP or estimating the MEn/DE ratio from the food CP content by the following equation: MEn/DE=0.98 - 3.44 +/- 0.517 x CP (kg/MJ DE).
Evaluation of the amount of metabolizable energy in the dogfood quantities recommended by the manufacturers to be fed daily to dogs, in relation to their energy requirements
RESUMEN El objetivo del estudio fue determinar el aporte de energia metabolizable (ME) de las dietas al ser suministradas en las cantidades recomendadas por los fabricantes de alimentos comerciales a perros adultos en mantencion y en crecimiento y compararlas con los requerimientos energeticos del perro. Se evaluaron marcas comerciales de alimentos secos formulados para perros adultos en mantencion (15 marcas) y perros en crecimiento (15 marcas). Se confeccionaron muestras compuestas a partir de 3 lotes por formulacion, las que fueron molidas y mezcladas con el marcador indigestible Cr 2 O 3 . Cada dieta para perros adultos en mantencion fue suministrada a 8 perros adultos y cada dieta para perros en crecimiento fue suministrada a 8 perros en crecimiento, todos de la raza Labrador Retriever, por un periodo experimental de 8 dias, luego de 8 dias en los cuales los perros recibieron una dieta base. Durante los dias 6, 7 y 8 de cada periodo experimental se recolectaron muestras de fecas individuales. A cada dieta se le determino la concentracion de ME. El contenido de ME en las cantidades de las dietas recomendadas por las fabricantes de los alimentos en perros adultos (10, 20 y 30 kg peso vivo) y perros en crecimiento (12 y 24 kg peso vivo) fue comparado con los requerimientos de ME calculados para estos animales. Dependiendo del peso vivo considerado para los perros, hasta 40% y 40% de las marcas recomendaron cantidades de su alimento que suministran menos ME y mas ME, respectivamente, que el requerimiento del perro. Alimentar a los perros con las cantidades recomendadas de alimento podria llevarlos a una condicion corporal por debajo o por encima de la correcta.
[Proper energy evaluation of commercial laboratory animal diets based on digestibility and metabolizable energy values].
The energy values of commercial laboratory animal diets have been customarily calculated by applying physiological fuel values (PFV) in this country. In order to ascertain accuracy of this application, apparent digestibility of crude protein, crude fat, nitrogen-free extracts (NFE), carbohydrate (NFE + crude fiber) and nitrogen-corrected metabolizable energy (MEn) of 10 commercial diets were determined using rats, dogs, rabbits and guinea pigs, respectively, and true digestibility of crude protein and crude fat of 12 feed ingredients was determined using rats. Apparent digestibility of the nutrients in the diets decreased with an increase in the crude fiber content of the diets. MEn values of the diets ranged between 2.18 and 3.75 kcal per g dry matter depending upon the crude fiber content of the diets. The energy values of the 10 diets calculated using PFV values of 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat were compared with each MEn. The calculated values were 1.04 to 1.39 times higher than those of the respective MEn. All of the diets and most feed ingredients did not show high digestibility of nutrients assumed for the application of PFV. Therefore, it is concluded that application of PFV to the diets results in over-estimation of energy values and use of PFV for commercial laboratory diets in our country is not warranted. It is advisable to use MEn to evaluate energy value of commercial laboratory animal diets.