What would be more fitting for a European event like the 2017 European Symposium on Poultry Nutrition (ESPN) than to focus on European protein sources? There were a good number of research reports focusing on vegetable protein sources that are grown in European soil. As it happens, the major protein source in Europe remains soybean meal.
Now, there is nothing wrong with this ingredient, and indeed it is considered a prime one by anyone involved in animal nutrition, but Europe is just not suited for growing this crop. Not only is the majority of the crop land in areas unsuitable for soybeans (too cold or not enough water), but also the high yield soybean cultivars are nowadays of GMO origin, something that is not allowed in the European Union. Thus, the majority of soybean meal used in Europe is imported at a considerable cost, and as a result, researchers continue the search for alternatives.
In recent years, rapeseed has been brought back into focus in the “old world” of Europe, if only because its oil is a major raw material for the production of biodiesel. Other crops, however, are becoming increasingly more available, including fava beans, peas and even lupins, something usually associated with Australia. Sunflower meal is always available, at least in the Eastern parts of Europe, but it is not well understood or even appreciated. We shall next examine research reports from the ESPN 2017 event that deal with these protein-rich ingredients, always within the context of using them in poultry feeds.
Today, with the abundance of rapeseed in Europe, there is an interest in dispensing altogether with soybean. A German trial reported that total replacement of 21 percent soybean meal in brown layer diets with rapeseed meal and peas resulted in reduced egg weight and deteriorating feed efficiency.
It appears that either the energy/methionine levels in the alternative ingredients require further refining, and/or anti-nutritional factors remain high when using both alternative protein sources. It must have been an overestimation of available methionine, which usually controls egg weight, because energy in rapeseed meal appears to be of rather limited variability. At least, this was the case in a British research project where 10 varieties of locally produced rapeseed were tested for apparent metabolizable energy (AME; MJ/kg) in rapeseed meal. Mean AME was 10.9 MJ/kg, ranging from 10.37 to 11.51 MJ/kg with a a CV equal to 5.91 percent. Apparently, the non-starch polysaccharides (NSP) concentration in rapeseed is also rather stable, too.
Sunflowers are cultivated in abundance in eastern Europe, but their utilization remains rather limited. An effort has been made to concentrate the protein in sunflower meal, resulting in a sunflower protein isolate with 82 percent crude protein, a product very similar to soy protein isolate.
A Russian research team reported on the substitution of 4 percent fish meal in broiler diets by this sunflower protein isolate. The replacement was done at 25, 50, 75 and 100 percent of fish meal and at each level performance was not much different than that of the positive control. It would have been better if a statistical analysis was included, and even better if a negative control (0 percent fish meal) was included as one can always replace practically anything that is not needed if something harmless is used. Nevertheless, this appears to be an interesting product that can have many low-cost applications.
One of the benefits using soybean meal is its rather standard composition due to limited genetic choices in growing soybeans. When it comes to protein sources that are not “mainstream” like fava beans, which are already a rarity even as a human food, variability becomes a concern. For example, 10 varieties tested in the U.K. revealed that although overall amino acid digestibility in broilers is medium-high at 81 percent (compared with 86 percent in soybean meal), individual digestibility ranged from 62 percent (proline) to 86 percent (lysine). And not only was variability great within each variety among the several amino acids, but also there was great variability for the same amino acid among the tested varieties of fava beans.
Thus, methionine had a rather unacceptably high coefficient of variation of 12.6 percent among the different varieties, whereas, another example, for lysine the same coefficient was only 4.2 percent. It appears that before using fava beans, its amino acid composition should be determined and digestibility values calculated from research such as this presented by Harper Adams University.
As reported above, peas cannot be combined with rapeseed to support performance in brown layers equal to that enjoyed by an all-soybean meal-based diet. But, extruded peas may be the answer as reported by a Polish study. In this project, increasing raw pea concentration from 10 to 50 percent in a broiler diet resulted in reduced performance and reduced utilization of apparent metabolizable energy (AME) and nutrients. In contrast, birds fed extruded beans did not exhibit any of the above. It was observed that extrusion reduced phytic acid and resistant starch concentrations.
Blue and white lupines of low-alkaloid content varieties were tested in Germany and Poland in diets for broilers and layers, respectively. Blue lupines successfully replaced about half of dietary soybean, giving a maximum inclusion level of 15 percent in the diet. Lamentably, the researchers did not test higher levels of lupines in this trial. But this was not the case in the Polish trial, where layers were fed diets containing up to 30 percent white lupines. Here layer performance was negatively affected when lupine concentration exceeded 18 percent in the diets. When the two studies are reviewed together, we derive a rather generic 15 to 20 percent upper maximum specification limit for lupines in poultry diets.
For more information, full research reports can be found in the proceedings book that was published by Wageningen Academic Press.