The application of dual-energy X-absorptiometry to nutrition and yield dynamics research in poultry

The objective of the present study was to calibrate and validate the use of dual-energy X-absorptiometry (DEXA) for the determination of processing yield and to apply it to the study of yield dynamics in broilers. 242 male Cobb 500 birds coming from different nutrition experiments were sampled at different ages between 4 and 69 d (95 to 6300 g of body weight; BW), DEXA scanned and cut up to measure processing yield. Multiple linear regression models were developed on JMP 13.2 using the results from DEXA as predictors. The measured and predicted values were compared and correlation coefficients determined. In addition, a total of 220 male Cobb 500 birds fed a standard diet with or without the addition of an exogenous combined enzyme product were sampled and DEXA scanned (22 time points between 0 and 42 d; 5 birds sampled per treatment and age) and Gompertz curves were adjusted and compared (equivalence test for inflection point, growth rate and asymptote estimates) for BW, protein, fat and mineral contents in the body, and for carcass, breast, tenders, wings and leg quarters weights. Different non-linear models were adjusted to determine yield (%) dynamics of each part of the body. Finally, specific time points were compared using a t-student test. Multiple linear models were obtained for carcass, fat pad, breast, tenders, wings and leg quarters, being the adjR2 values 0.995, 0.801, 0.971, 0.974, 0.988 and 0.988 for the actual weight (g) of each piece, and 0.935, 0.752, 0.921, 0.878, 0.780 and 0.793 for the relative (%) values, respectively, with no statistical differences (P>0.10) found between measured and predicted values. No differences were found between treatments when the Gompertz curves of BW and body composition were compared (P>0.05); however, the birds fed the enzyme showed curves with different trends between 10 and 25 days of age and statistically different values (P<0.05) were detected in yield (%) (breast, wings, fat pad) at specific time points within that period, being the breast yield higher for the enzyme fed birds. The results of the present study support the capability of the specific DEXA machine evaluated to determine processing yield in broilers and its application to the study of yield dynamics in poultry nutrition research.

Key Words: dual-energy X-absorptiometry, breast, processing yield, broilers, body composition.

Abstract presented at the International Poultry Scientific Forum during IPPE 2020.