The present study was carried out at the Institute for Animal Nutrition and Teaching and Research Farm of the University of Veterinary Medicine Vienna. The objectives of this study were to investigate the effects of physical processing like crushing and heat treatment of canola seed on rumen characteristics and the performance of growing lambs. Main focus of the study was the influence of processing on the fatty acids profile of the meat and fat of lambs. The first part of the study include of four degradation trails which were carried out to determine nutrients degradability, ruminal biohydrogenation of unsaturated fatty acids and rumen fluid characteristics using rumen simulation technique (Rusitec). The experimental rations included whole canola seed (WCS), whole canola seed (HWCS) heated at 127 °C for 15 minutes, crushed canola seed (CCS) and crushed canola seed (HCCS) heated at 127 °C for 15 minutes. The rations consisted of 70 % concentrate mixture and 30% grass hay. Canola seed was added at a rate of 10 % from the concentrate mixture. The results can be summarized as follows: Crushing and heat treatment had little effect on nutrient composition of canola seed. Crushing of canola seed decreased slightly crude fiber (CF), nutrient detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) compared with WCS. Heating of WCS decreased CF but increased dry matter (DM) and NFE. Also, HCCS had decreased hemicelluloses and increased DM compared with CCS. Fatty acids profile of canola seed was not altered by crushing or heat treatment.
Crushing of canola seed improved significantly degradability of most nutrients compared with whole canola seed. Also, crushing increased significantly biohydrogenation (BH) of long chain fatty acids, ammonia concentration, concentration of total volatile fatty acids (VFA), acetate, propionate, n-butyrate and iso-valeriate in the rumen. On the other hand, crushing decreased significantly pH, redox potential, gas production, iso-butyrate and n-valerate in the rumen compared with WCS.
Heat treatment markedly influenced on nutrient degradability of whole rather than crushed canola seed in the rumen. The degradability of DM, organic matter (OM), crude protein (CP), ether extract (EE), nitrogen free extract (NFE), NDF and hemicellulose of HWCS was higher compared with untreated WCS. However, the effect of HCCS on nutrients degradability was small. Similar to crushing, heat treatment of whole and crushed canola seed increased significantly the biohydrogenation (BH) of long chain fatty acids, the ammonia concentration, the concentration of total VFA especially acetate and propionate in the rumen. A significant lower in pH and redox potential was noted in rations containing HCCS than in those containing CCS. Contrary, pH value and redox potential was not affected by heat in HWCS ration. From degradability trial and the data of growing performance of lambs, this study suggests that heat treatment of whole canola seed at 127 °C for 15 minutes has a positive effect on the extent of rumen escape of nutrients in canola seed, improves rumen fermentation, decreases BH of FA and increases that of polyunsaturated FA in lambs meat and fat, thus improving their fatty acid profile for human consumption.
From the results of this study it can be concluded that incorporating 10 % heated whole canola seed to the concentrate mixture as a substitute for cottonseed cake in lambs rations can improve nutrients degradability and the performance of growing lambs without causing physiological disorders.