Abstract
The European poultry feed industry faces challenges linked to climate change or shifting economic situation. Sorghum, a drought-tolerant crop, represents a promising alternative to maize in poultry diets. However, grain quality traits, such as protein content and digestibility, are not yet prioritised in selection programs. This study assessed the digestibility of five sorghum varieties selected for their crude protein (CP) and tannin contents.A total of 102 Ross 308 male broilers were housed in individual cages at D22 and assigned to one the six experimental diets. The first diet was a control one (C). The five others were composed of 75% C and 25% of one of the five tested sorghum varieties with four tannin-free CIRAD01 (12.1% CP), MACIA (11.4% CP), TX623 (10.7% CP), ISN60C (9.5% CP), or SC59 (10.7% CP; tannin-containing). Diets included 2% celite as an indigestible marker. Individual faeces were collected to evaluate the total tract apparent digestibility (TTAD) of dry matter (DM) and nitrogen (N, corrected or not for uric acid excretion). After this period, birds were sacrificed to collect ileal content and evaluate the apparent ileal digestibility (AID) of amino acids (AA). Data were analysed using a one-way ANOVA.The TTAD of DM and N, differed significantly among varieties (p=0.002 and 0.001, respectively). The ISN60C variety showed the highest digestibility of DM and N (86.5% and 80.2%, respectively), while the SC59 one had the lowest N digestibility (66%). However, this effect of varieties is lost when N is correted (p=0.66). In SC59, the AID of five AA was also found to be significantly lower, including cysteine (77.7%; p=0.002) and arginine (87.1%; p=0.01), most likely in relation with the presence of tannins. ISN60C and MACIA showed the highest digestibility coefficients. This may be attributed to differences in the composition in kafirins , known to affect protein digestibility and other grain storage proteins. Certain sorghum varieties could indeed possess particular protein composition that mitigate this negative effect of kafirins, a hypothesis currently under investigation.Further analyses, including metabolisable energy evaluation, are also underway to provide a more comprehensive assessment of the nutritional characteristics of these sorghum varieties.