Potential use of rapeseed (canola) meal as a protein source in poultry diets

Imported rapeseed meal (RSM) from India and China, a plant protein source in animal feed, contained 38.1-40.2 percent CP, 2.7-3.4 percent EE, 15.7-18.4 percent CF, 9.0-9.1 percent ash, 1.74 kcal ME/g and glucosinolates 75.3 micromole/g DM. The contents of lysine and tryptophan were rather low, being 1.83 and 0.51 percent DM, which were 78-80 percent of soybean meal (SBM) while sulfur amino acids (methionine and cystine) were 50 percent higher than those of SBM. The digestibility of nutrients in RSM was around 36-45 percent with the exception of CF which was very low, only 14 percent. The potential use of RSM was investigated in broilers and layers. In broilers, RSM was substituted for SBM at 50-100 percent which was equal to 10-26 percent of the diets. They were fed to 720 heads of 1-week-old Hubbard broiler chicks for a 6 weeks period. The result revealed that feed intake and body weight gain decreased while mortality and culling rate tended to increase with the increased level of RSM. However, there was no adverse effect on feed conversion ratio. The size and follicular lumen of thyroid glands increased whereas thyroxin decreased with the increased level of RSM, particularly at the 75 percent substitution level. The weight of pancreas inflated while that of visceral plus abdominal fat deflated significantly in the groups fed with RSM. For laying hens, RSM was used to substitute 25-100 percent SBM, which was equal to 4-16 percent of the diet. The experimental diets were either adjusted or unadjusted to be isocaloric (ME) to the control diet. Three experiments, each lasted 9 months, were conducted using Hubbard pullets. It was found that feed intake and egg production deflated with the increased level of RSM. At the 50 percent substitution level, egg production was not significantly different from the control group. When ME of the diets was adjusted with rice bran oil, egg production performance was improved but not on the adjustment with tallow. Egg size in all experiments was inferior with the increased RSM level.