Cereal and soya diets are the preferred diet of many pig producers and nutritionists. However when markets are volatile maintaining cereal and soya levels can impact significantly on diet cost.
The main issue is never diet cost in terms of price per tonne, but the overall value and return. If a cheaper diet negatively affects performance it can be more costly than paying for a more expensive one.
The research consortium of John Thompson and Son’s Ltd, Devenish and Agri-Food and Biosciences Institute, Hillsborough with co-funding from DARD, set out to evaluate the inclusion of by-products of cereals and oilseeds in finisher diets.
The questions to be answered were; did they affect performance, at what level could they be included, what cost did cereals, soya and by products need to be to make their inclusion economically viable?
The first work looked at by-products such as pollard and maize gluten with additional oil against cereal and soya diets. Growth rate of pigs offered the cereal and soya diet was 4% better than that of pigs offered the by-product diets. However, for feed efficiency there was no difference. Having quantified the difference in performance, we now can make qualified decisions on the relative economic value of these raw materials on overall cost of production (see graph)
Globally vegetable protein is becoming a valuable and much sought after resource. Alternative proteins have to be considered if pig production is to remain sustainable. Rapeseed meal is the protein we know most about after soya.
Using good quality rapeseed meal (analysed to ensure low anti nutritive properties); the consortium evaluated its inclusion in finisher diets up to 21%.
Results were inconsistent across trials but showed that rapeseed meal can be included at conservative levels in finisher feeds with no impact on performance.
Currently the consortium is investigating the use of a by-product from the biofuel industry called Dried Distillers Grains with Solubles (DDGS) from both wheat and maize origin and trialling finisher pig diets with DDGS levels up to 30%.
In addition to knowing the nutritive value of protein from different raw materials it is also critical to be aware of the major variation which exists in the protein content of individual raw materials.
Through analysis of raw ingredients locally over the past two years, it was found that the crude protein (CP) content of barley can range from 8.5 to 11.6%, for wheat between 7.9 and 12.9%, and for soya between 44.4 to 49.4% depending on source, country of origin etc.
Assuming a finisher pig diet contained 40% wheat, 20% barley and 23% soya then the implications of this variation would equate to a reduction of between 3 and 4% in crude protein content if the ingredients were all at the lower end of the range of proteins and if not accounted for correctly in the formulation.
Consistency is key and having knowledge of raw material properties, knowledge of raw material performance, knowledge regarding optimum inclusion level and most importantly knowledge of nutrient analysis of ingredients will help achieve this consistency.