Development of a protein food based on texturized wheat proteins, with high protein digestibility and improved lysine content.

The development of plant-based protein foods may facilitate the decrease in animal product consumption in western countries. Wheat proteins, as a starch coproduct, are available in large amounts and are good candidates for this development. We investigated the effect of a new texturing process on wheat protein digestibility and implemented strategies aimed at enhancing the lysine content of the product developed. Protein true ileal digestibility (TID) was determined in minipigs. In a preliminary experiment, the TID of wheat protein (WP), texturized wheat protein (TWP), TWP enriched with free lysine (TWP-L), or with chickpea flour (TWP-CP) was measured and compared to beef meat proteins. In the main experiment, minipigs (n = 6) were fed a dish (blanquette type) containing 40 g of protein in the form of TWP-CP, TWP-CP enriched with free lysine TWP-CP+L, chicken filet, or texturized soy, together with quinoa (18.5 g of protein) in order to improve meal supply of lysine. Wheat protein texturing did not affect total amino acid TID (96.8 % for TWP vs 95.3 % for WP), which was not different from that of beef meat (95.8 %). Chickpea addition did not affect protein TID (96.5 % for TWP-CP vs 96.8 % for TWP). The Digestible Indispensable Amino Acid Score for adults of the dish combining TWP-CP+L with quinoa was 91, whereas it was 110 and 111 for the dishes containing chicken filet or texturized soy. The above results show that, by optimizing lysine content through the formulation of the product, wheat protein texturization can enable the development of protein-rich products of nutritional quality compatible with quality protein intake in the context of a complete meal.

Protein metabolism, body composition and oxygen consumption in young bulls divergent in residual feed intake offered two contrasting forage-based diets.

Protein metabolism and body composition have been identified as major determinants of residual feed intake (RFI) in beef cattle fed high-starch fattening diets. This study aimed to evaluate if these two identified RFI determinants in beef cattle are the same across two contrasting silage-based diets. During two consecutive years, an 84-day feed efficiency test (Test A) immediately followed by a second 112-day feed efficiency test (Test B) was carried out using a total of 100 animals offered either one of two diets (either corn silage- or grass silage-based) over 196 days. At the end of Test A, the 32 animals most divergent for RFI (16 extreme RFI animals per diet, eight low RFI and eight high RFI) were identified and evaluated during Test B for their i) N use efficiency (NUE; N retention/N intake) calculated either from a 10-d nitrogen balance trial or from estimations based on body composition changes occurring during the whole experiment (Test A and Test B; 196 days), ii) carcass and whole-body protein turnover rates analysed through the 3-methyl-histidine urinary excretion and the N isotopic turnover rates of urine, respectively, and iii) body composition measured at the slaughterhouse at the end of Test B. Oxygen consumption was measured during Test B for the 100 animals by two GreenFeed systems. Irrespective of the diet, efficient RFI animals tended (P = 0.08) to improve their NUE when N retention was estimated for 196 days or when considering their lower urinary urea-N to total N ratio (P = 0.03). In contrast, NUE calculated during the 10-d N balance showed no differences (P = 0.65) across RFI groups suggesting that this method may not be suitable to capture small NUE differences. Efficient RFI individuals presented higher dressing percentage and muscle deposition in the carcass (P = 0.003) but lighter rumen (P = 0.001), and a trend for lower oxygen consumption (P = 0.08) than inefficient RFI animals irrespective of the diet. Lower protein degradation rates of skeletal muscle and lower protein synthesis rates of plasma proteins were found in efficient RFI cattle but only with the corn silage-based diet (RFI × Diet; P = 0.02). The higher insulinaemia associated with the corn silage-based diet (P = 0.001) seemed to be a key metabolic feature explaining the positive association between protein turnover and RFI only in this diet. Feed N was more efficiently used for growth by efficient RFI animals regardless of the diet but lower protein turnover rates in efficient RFI animals were only observed with corn silage-based diets.