High-protein canola meal can work as an alternative protein source
Tuesday, December 8, 2015
New research suggests that both high-protein and conventional canola meal can fully replace soybean meal in diets fed to grower-finisher pigs without hurting performance, visceral mass, carcass characteristics or meat quality
by JANICE MURPHY
Researchers at the University of Illinois have recently been focusing their attention on canola meal as an alternative to soybean meal in swine diets. With the increasing demand for soybean meal in all areas of agriculture and aquaculture, identifying suitable alternative protein sources is key to maintaining a viable feed supply.
Conventional canola meal is lower in crude protein and contains more fibre than soybean meal, which can limit the availability of essential amino acids and digestible energy in swine rations. The additional fibre load can also have an influence on gut fill, increasing intestinal mass and ultimately affecting carcass yield. And canola meal is known to contain glucosinolates, an anti-nutritional factor that can interfere with average daily gain and muscle growth.
Recently, a new hybrid variety of canola has been developed with higher protein and potentially higher energy than conventional varieties. Since meal from this variety yields approximately 45 per cent crude protein, it may be a more suitable alternative to soybean meal.
To date, comparisons of conventional and high-protein canola have been performed in weaner pig diets, but little information has been available on the use of high-protein canola meal on grower-finisher pigs. A recent study set out to assess growth performance, visceral mass, carcass characteristics and meat quality in grower-finisher pigs fed diets formulated with either high protein or conventional canola meal in place of soybean meal.
Seven dietary treatments were formulated to assess increasing inclusion rates of canola meal in a corn-soybean meal diet containing no canola meal (control). Inclusion rates were set at a replacement rate of 33, 66, or 100 per cent soybean meal with either high-protein or conventional canola meal. Pigs (280 total; 140 barrows and 140 gilts) were fed the experimental diets over three phases lasting 35, 28 and 28 days, respectively. Within each phase, diets were formulated to be similar in concentrations of standardized ileal digestible indispensable amino acids and total tract digestible phosphorus, but energy concentrations were not equalized among diets. At the conclusion of the experiment, one pig per pen was harvested.
Over the course of the 91-day grower-finisher trial, there was no significant impact of the high protein canola meal diet on average daily gain (ADG), average daily feed intake (ADFI) or feed efficiency, but final bodyweight tended to decrease with increasing levels of high protein canola meal (Table 1). There was a significant linear increase in ADFI and linear decrease in feed efficiency as conventional canola meal inclusion level increased.
The data revealed that there was a significant linear increase in liver weights as a percentage of live weight, as the inclusion rate of conventional canola meal increased, but that was not the case for high protein canola meal. There was also a significant linear increase in kidney weights, as a percentage of live weight, as either high protein or conventional canola meal inclusion increased.
There were no significant differences between treatments in final live weight, hot carcass weight, carcass yield, loin eye area, tenth rib backfat thickness or estimated carcass lean (Table 1).
The same was true for the majority of the meat quality characteristics that were assessed (shear force, cook loss, drip loss, colour, marbling or firmness). Pigs fed high-protein canola meal did exhibit significantly higher boneless lean cutting yields and boneless carcass cutting yields compared with pigs fed conventional canola meal.
The canola varieties used in this study contained less than the 30 µmol/g glucosinolates which is generally considered to be the threshold for causing potentially negative effects. Previous research has reported that between 15 and 30 per cent canola meal can be included in diets fed to growing-finishing pigs without changing growth performance. This was obviously not the case here. The diets with the highest concentration of canola meal in this study tested at five to six µmol/g glucosinolates.
Results from this experiment demonstrated that both high-protein and conventional canola meal can fully replace soybean meal in diets fed to grower-finisher pigs without hurting growth performance, visceral mass, carcass characteristics, or meat quality. This is the first study that has provided such results.
Based on this, the researchers feel confident in suggesting that, if diets are formulated to contain equal quantities of digestible phosphorus and digestible amino acids, either high-protein or conventional canola meal can be used as the major protein source in corn-based diets fed to grower-finisher pigs. BP
Janice Murphy is a former OMAFRA swine nutritionist who now lives and works in Prince Edward Island.
