Towards protein autonomy for feeding ruminants - the Proleval project

Abstract

In order to ensure better protein autonomy for feeding livestock, various levers - including the development of protein crops - are possible. The Proleval project was part of this perspective. The effects of technological treatments on the valorization of oilseeds and protein grains by dairy cows were evaluated. A literature review allowed to quantify the almost systematic beneficial effect of thermal or thermomechanical treatments of seeds on the nitrogen utilization: decrease in ruminal degradability, increase in intestinal digestibility, supply of essential amino acids, and protein secretion in milk. However, the observed effects are quantitatively variable depending on the treatment. New experiments conducted within this project allowed to specify the effects of some extrusion characteristics on faba bean and lupin seeds: extrusion temperature and maturation by innovative processes with reducing sugars or an enzymatic cocktail. The results obtained by various approaches (in situ degradability and digestibility measurements, in vivo nitrogen balance trials on dairy cows) show that extrusion temperature must be limited to avoid over-protection of proteins, and that maturation pre-treatments tested are not systematically efficient. The few published results on the milk lipid fraction report a decrease in milk fat content with the treated seeds when compared with the raw ones. Few studies present milk fatty acid profiles, but data from Proleval project indicate than extruded seeds promote trans fatty acids production in rumen and milk. Controlling the extrusion conditions to produce a product with optimal nutritional characteristics in a repeatable manner, which appears to involve controlling the development of Maillard compounds, remains a challenge.