FFECTS OF DIETARY FLOUR AND OIL FROM TOWER RAPESEED ON FOOD INTAKE, WEIGHT GAINS, NUTRIENT DIGESTIBILITY, ENERGY UTILIZATION AND BODY COMPOSITION OF RATS

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Abstract
Rats were fed diets containing 15% protein, 10% fat and 4.7 kcal/g in the form of: (1) soybean flour–corn oil (SBF/CO), (2) Tower rapeseed flour–corn oil (RSF/CO) and (3) Tower rapeseed flour–Tower rapeseed oil (RSF/RSO). Rats fed the SBF/CO diet ate more and grew faster than rats fed the RSF diets (P < 0.05). However, rats fed the RSF/RSO diet converted food to weight gain more efficiently than rats receiving the SBF/CO diet (P < 0.05). The digestibility of the dry matter (92%), energy (94%) and protein (88%) of the RSF diets was higher than that of the SBF diet (P < 0.01). Digestibility of the RSO was higher than that of the CO only when SBF was used as source of dietary protein. The net protein utilization of the diets throughout the experiment was similar (43–48%). Energy retention as percent of intake was similar for all diets (20–26%); however, rats receiving the RSF/RSO diet deposited a greater proportion of the caloric intake as tissue protein than rats receiving the SBF/CO diet (10.0 vs. 8.8%, respectively, P < 0.05). Body composition after 7 days on the experimental diets was not affected by the dietary treatments. Heart weights (mg DM/g body DM) of rats fed the RSF/RSO diet were greater than those of rats receiving the SBF/CO diet (4.3 vs. 3.5 mg/g body DM, respectively, P < 0.05). After 21 days, rats fed the SBF/CO diet had deposited more body fat than rats receiving the RSF diets (12.7 vs. 9.7 and 10.1% for SBF/CO, RSF/CO and RSF/RSO respectively, P < 0.05). No other differences in body composition were observed. The nutritive value of Tower rapeseed flour and oil was higher than that of soybean flour and corn oil. No toxic effects were observed from feeding rapeseed flour or oil to rats. However, the consumption of rapeseed flour was lower than that of soybean flour, possibly due to gut fill, since the "packed volume" occupied by the RSF diet was 1.5 times larger than that of the SBF diet. Texture and palatability of the flours may have also contributed to the differences in intake.