In this review canola meal (CM), its nutritionally significant components and the availability of its nutrients to poultry, pigs and cattle were discussed. Avenues for possible improvement in available energy, protein and lysine were identified. Recent findings on glucosinolates were also discussed with the conclusion that a further reduction of glucosinolates through plant breeding is both possible and desirable. The role of the anti-nutrients sinapine, tannins and phytic acid were also considered. The potential impact of improvements to CM on its economic value was examined using linear program least-cost ration formulations applied to typical market situations. Key words: Canola meal, energy, protein, carbohydrates, anti-nutritional factors, economics

The composition of rapeseed meal and hulls is reviewed with emphasis on components of nutritional interest. Carbohydrates in rapeseed meal are mainly pectins, pentosans and cellulose and comprise nearly one-half the gross energy. The digestibility of energy is lower for rapeseed than for soybean meal. Protein is well digested, but the protein digestion coefficient and the availability of amino acids are lower than for soybean meal. Data on digestible and metabolizable energy are summarized. The kinds of glucosinolates present in high (HG) and low (LG) glucosinolate rapeseed meal and the nature of their hydrolytic products are discussed. The toxic effects of oxazolidinethione , isothiocyanates, thiocyanates and nitriles, and their relationship to their parent glucosinolates , to myrosinase action and to conditions during rapeseed processing are reviewed briefly. The effects of glucosinolates in animal tissues and products and the effects of converting to LG rapeseed meal are presented. Finally, a brief review is given of the responses of swine and cattle to the feeding of HG and LG rapeseed meal. The nutritional advantages of LG rapeseed meal, over the older type HG meal, are clearly evident from the feeding trials.

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Despite numerous applications of time‐domain reflectometry (TDR), serious difficulties remain in estimating accurate soil water contents under field conditions, especially in fine‐textured soils. We developed a physically based calibration model to predict the frequency‐ and temperature‐dependent complex dielectric response of soils. The model was used to predict frequency‐dependent attenuation and a single “effective” frequency approximation of apparent permittivity of the soil. Effective frequency was predicted to decline from 450 to 160 MHz as water contents increased from air dry to saturation. Predicted frequency decline was small for an input bandwidth of 130 MHz, reflecting that modeled polarization mechanisms associated with relaxation frequencies above 100 MHz were responsible for most of the frequency‐dependent attenuation. For specific surface areas ranging from 150 to 300 m2 g−1, simulations indicate that ignoring dielectric and conductive losses or the associated decline in effective frequency results in a 5 to 22% underestimation of the apparent permittivity. Both the power‐law and de Loor–Dobson mixing models gave a reasonable approximation to the measured apparent permittivity for a silty clay loam (34% clay) across the entire water content range. Moreover, the models were able to describe the behavior of apparent permittivity in response to temperature for two soils with contrasting bulk electrical conductivity contributions to losses. These results demonstrate that loss mechanisms and declines in effective frequency need to be considered to accurately predict the soil water content of fine‐textured soils.

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