Prediction of metabolisable energy value of broiler diets and water excretion from dietary chemical analyses

Abstract

Thirty various pelleted diets were given to broilers (8/diet) for in vivo measurements of dietary metabolisable energy (ME) value and digestibilities of proteins, lipids, starch and sugars from day 27 to day 31, with ad libitum feeding and total collection of excreta. Water excretion was also measured. Amino acid formulation of diets was done on the basis of ratios to crude proteins. Mean in vivo apparent ME values corrected to zero nitrogen retention (AMEn) were always lower than the AMEn values calculated for adult cockerels using predicting equations from literature based on the chemical analyses of diets. The difference between mean in vivo AMEn values and these calculated AMEn values increased linearly with increasing amount of wheat in diets (P 5 0.0001). Mean digestibilities of proteins, lipids and starch were negatively related to wheat introduction (P 5 0.0001). The correlations between mean in vivo AMEn values and diet analytical parameters were the highest with fibre-related parameters, such as water-insoluble cell-walls (WICW) (r 5 20.91) or Real Applied Viscosity (RAV) (r 5 20.77). Thirteen multiple regression equations relating mean in vivo AMEn values to dietary analytical data were calculated, with R 2 values ranging from 0.859 to 0.966 (P 5 0.0001). The highest R 2 values were obtained when the RAV parameter was included in independent variables. The direct regression equations obtained with available components (proteins, lipids, starch, sucrose and oligosaccharides) and the indirect regression equations obtained with WICW and ash parameters showed similar R 2 values. Direct or indirect theoretical equations predicting AMEn values were established using the overall mean in vivo digestibility values. The principle of indirect equations was based on the assumption that WICW and ashes act as diluters. Addition of RAV or wheat content in variables improved the accuracy of theoretical equations. Efficiencies of theoretical equations for predicting AMEn values were almost the same as those of multiple regression equations. Water excretion was expressed either as the water content of excreta (EWC), the ratio of water excretion to feed intake (WIR) or the residual value from the regression equation relating water excretion to feed intake (RWE). The best regression predicting EWC was based on sucrose, fermentable sugars (lactose 1 oligosaccharides) and chloride variables, with positive coefficients. The best equations predicting WIR or RWE contained the sugar and chloride variables, with positive coefficients. Other variables appearing in these equations were AMEn or starch with negative coefficients, WICW, 'cell-wall-retained water', RAV or potassium with positive coefficients.

Prediction of the net energy value of broiler diets

“…Birds for measuring AMEn and NE values were placed in two different rooms having the same environmental conditions. Diets, bird management, housing system and results of AMEn data were previously reported (Carré et al, 2013). The whole experiment was divided into three successive trials at 4 weeks interval.…”

“…Among the 20 other groups, 10 were used for measurements of NE and growth performances, each group being randomly allocated to a specific experimental diet. The last 10 groups received the same diets for measurements of AMEn and digestibilities (Carré et al, 2013). Each bird was placed at random in individual wire cages (44 cm length, 33 cm width and 50 cm height) supplied with individual feeder and drinker, in two environmentally controlled rooms (a room for ME and another for NE determinations), as previously described by Carré et al (2013).…”

“…Then, each frozen carcasses were first cut in small pieces with an electric band saw and ground with an electric table top meat grinder. Ground carcasses were freeze-dried and individually analysed for nitrogen (Kjeldahl method) and lipids, with no acidic treatment before the lipid extraction by petroleum ether (Carré et al, 2013). A pooled sample of feathers was also analysed for their nitrogen content.…”

“…A first publication (Carré et al, 2013) reported in vivo measurements and predictions of AMEn values. In the current publication, in vivo measurements, calculations and predictions of NE values are reported using the same set of experimental data (Carré et al, 2013). NE values were determined with the method based on body analyses, measuring protein and lipid depositions from 21 to 35 days.…”

Predicting feed digestibility from NIRS analysis of pig faeces

“…It is, therefore, essential to know precisely the nutritional value of resources and to adapt the formulation matrices to the actual value of these resources. Because of the high cost of in vivo measurements of energy and nutrient digestibility, especially in large-sized animals such as pigs, feed characterization is most often performed by chemical analysis of samples and by the application of prediction equations that relate the composition vector to nutritional properties for a category of animals (Le Goff and Noblet, 2001;Carré et al, 2013). It can also be performed by NIRS with calibration equations predicting nutritional value from feed spectrum within a specific family of ingredients (e.g.…”