Effects of mechanical treatment of whole canola seeds on performance, diet digestibility and rumen parameters of lambs fed grass silage

Thirty-three lambs (25.2 +/- 2.7 kg body weight) were used to determine if mechanical treatment of canola seed could improve the performance of growing lambs and diet digestibility. All lambs received a basal diet of 179 g d(-1) of a 16% crude protein (CP) commercial concentrate and grass silage fed ad libitum. The basal diet was supplemented with the following dietary treatments (dry matter basis): C, a control supplement supplying 182 g of a mixture of 66% canola meal and 34% canola oil; WCS, 187 g of whole canola seeds; RCS, 188 g of rolled canola seeds; and GCS, 189 g of ground canola seeds. Dry matter intake was similar for all diets. Average daily gain (ADG) was 20% lower (P < 0.001) for lambs fed whole or crushed canola seeds than for those fed the C diet. Lambs fed GCS had intermediate ADG between those fed C and those fed WCS and RCS diets. In general, apparent digestibility of C was higher (P < 0.01) than that of WCS and RCS and digestibility of GCS was intermediate. Rumen pH and molar proportions of individual volatile fatty acids (VFA) were not affected by treatments. Rumen ammonia-N concentration was similar among treatments. Utilization of whole canola seeds as a protein and energy supplement to grass silage resulted in lower performance of lambs compared to that obtained with a mixture of canola meal and canola oil.