St. Raj

Predicting the energy value of pig feeds using in vitro or analytical methods

Abstract An in vitro method, using ileal digesta or faecal extract as inocula, was used either alone or in combination with chemical composition to predict the content of metabolisable (ME) and digestible energy (DE) of cereals, yellow lupin and rape-seed oilmeal (either singly or in mixed feeds) for pigs. By means of regression analysis, in vitro dry matter solubilisation with ileal digesta (IDMS) and faecal extract (FDMS) as inoculum was found to be correlated to the in vivo ME (IDMS, r 2 = 0.94, cv = 1.13; FDMS, r 2 = 0.67, cv = 2.64 and DE (IDMS, r 2 = 0.90, cv = 1.40; FDMS, r 2 = 0,73, cv = 2.24) content of the feeds, when pure rape-seed oilmeal and yellow lupin were excluded. The correlations were further enhanced by combining IDMS with the starch, crude protein and dietary fibre content in the regression equations (ME, r 2 = 0.98, cv = 0.85; DE, r 2 = 0.97, cv = 0.92). In vivo metabolisable and digestible energy contents could also be predicted from chemical composition, employing either non-nutrients (ash and dietary fibre; ME, r 2 = 0.95, cv = 1.01; DE, r 2 = 0.93, cv = 1.23) or nutrients (starch, crude protein and crude fat; ME, r 2 = 0.93, cv = 1.37; DE, r 2 = 0.91, cv = 1.48). It is suggested that in vitro or appropriate dietary components, i.e. starch, crude protein and dietary fibre, could be employed to predict the nutritive value of feeds for pigs.

Energy metabolism in growing-finishing pigs fed rapeseed meal

Thirty six Landrace pigs from 60 to 110 kg liveweight were given diets of similar available lysine and metabolizable energy contents. The feed mixtures contained an average of 16% soya bean meal (SBM) or 21 % rapeseed meal (RSM) of a double-low variety (8.7 moles glucosinolates per g fat-free dry matter). Energy retention in the body was measured by the comparative slaughter technique. The weight of the internal organs and thyroid gland and T 3 and T 4 hormone concentrations in blood samples taken at slaughter were also determined. The weight of the thyroid and liver were 55 % (P ̂ 0.001) and 16% (P ̂ 0.001) higher, respectively, in the animals fed RSM. The RSM diet caused no significant difference in the chemical composition of the body gain, blood T 3 and T 4 levels as in the weight of the kidneys. The maintenance requirement and energy cost of protein deposition in the body of pigs did not differ between the groups (511 kJ/kg 7 5 /d and 68 kJ/g, respectively).