The Effect of Level of Feed Intake on Metabolizable Energy Values Measured with Adult Roosters

Abstract

Two experiments were made with S.C.W.L. roosters to test the hypothesis that the apparent M.E. value of a feedingstuff is affected by the level of intake. In the first experiment the birds were starved for 18 hr. and then fed varying amounts of whole wheat. Excreta voided during the 24 hr. experimental period was collected quantitatively and assayed for gross energy. Energy voided as excreta increased in a linear manner as the intake of wheat increased. The apparent M.E. value also varied with wheat consumption according to the equation M.E. (kcal./g.) = 3.17X - 8.5/X where: 3.17 kcal./g. is the true M.E. value of the wheat; 8.5 kcal. represents the sum of the metabolic fecal and endogenous urinary energy losses; and X is the weight of wheat consumed (g). A supplementary observation was that the metabolic fecal and endogenous nitrogen excretion of the roosters was 144 mg./kg./24 hr. In the second experiment corn oil was placed in the crops of starved roosters and the energy voided as excreta in 24 hr. was measured. The true M.E. value of the corn oil was 9.40 kcal./g. but the apparent value varied with intake. It is therefore concluded that the original hypothesis is correct. The findings of these experiments may explain some of the reported variations in M.E. data. A new approach to the assay for M.E. is proposed.

Measurement of Bioavailable Energy in Poultry Feedingstuffs: A Review

“…AME values should diminish with feed intake. The theory was proved experimentally by Sibbald (1975a) and confirmation may be found in several subsequent reports such as that of Muztar and Slinger (1980a). The dara of Farrell (1975) provide a basis for calculations showing that in nine of l3 comparisons restriction of feed intake deoressed dietarv AME values.…”

“…The size of the nitrogen correction should vary with nutrient intake as well as with protein quality and intake. Perhaps the large effects of the correction, reported by Leeson et al (1917) The FE*UE of adult cockerels remained unchanged when corn oil (Sibbald 1975a) and glucose (Sibbald 1976a Shires et al (1980) measured TME and TME" using chicks and adult cockerels.…”

“…The argument may be valid, but adjustment of requirement data seems a minor concern when compared with the beneficial effects of the correction. Correction of AME to TME controls much of the variation associated with differences in feed intake and also the "among-bird-type" variation caused by differences in the ratio of F-E+U.E loss to feed intake (Sibbald 1975a (McNab 1976) and ME (McNab and Fisher 1981) the need to correct for F-E * U.E losses is emphasized.…”

“…The semipurified reference diet may be more expensive than the practical diet but not enough to be cause for concern. However, the assay ofFarrell (1978a) (Sibbald 1975a(Sibbald , 1976aTenesaca and Sell 1979;Johnsson 1980;Shires et al 1980 where FE * UE is the energy voided by the fed bird and F-E * U.E is the mean of the energy voided by the unfed birds. The assay is described in greater detail elsewhere (Sibbald 1980d(Sibbald , 1981b).…”

Feed input and excreta collection time in metabolisable energy assays for ducks

“…At present, there are few reports on the bioassay method of duck feeds. Feed input and excreta collection time are two key factors influencing the accuracy of bioassay for true metabolisable energy of poultry feeds (Sibbald, 1975(Sibbald, , 1976Yaghobfar and Boldaji, 2002). Feeding and excreta collection techniques for ducks were developed by Adeola et al (1997) and modified by Hong et al (2002) based on ducks' specific physiology.…”