Hemp seeds have a high energy content, and are a traditional staple of mixes for pet birds because of their low cost. Seed-eating migratory birds are attracted to hemp fields at harvest time, and, in many countries, the seeds have been used as poultry feed (Khan et al., 2009). The high concentration of hemp seed oil in polyunsaturated fatty acids has led to renewed interest in hemp seeds and hemp seed oil meal for improving the quality of poultry products.
In Pakistan, up to 20% dried and crushed hemp seeds have been used successfully in broiler diets and resulted in higher breast, leg and thigh weight. This positive effect has been linked to the combination of a good protein and lipid quality associated to other beneficial properties, such as the lack of trypsin inhibitors and the antioxydant activity of cannabidiol (Khan et al., 2009). Feeding broilers with hemp seed powder (at 20%) resulted in better feed conversion ratio, higher live-weight gain, lower age at slaughter, and lower mortality rate (Khan et al., 2010). In Iran, hemp seed included at up to 7.5% in broiler diets had no detrimental effect on performance, and reduced serum cholesterol (Mahmoudi et al., 2012). It has been possible to partly replace soybean meal by hemp seed meal in broiler diets. Supplementation of hemp seed meal at 1.5-9.0% had no adverse effects on immunological factors. Levels of 1.5-3% might promote B cell differentiation and maturation as well as immunity. Levels of 4.5-7.0% enhanced nitrogen utilization (Ma Li et al., 2007). The inclusion of hemp seed cake in the diets of fast-growing organic broilers (10% at 10-28 days, 20% at 28-70 days) did not affect production performance or mortality. No effect of hemp seed cake inclusion in the feed was seen on the number of Clostridium perfringens in the caeca. The high fibre content in the hemp diet resulted in inferior litter condition likely affecting the leg and foot health of the birds, resulting in lesser use of outdoor pasture (Eriksson et al., 2012).
Several trials have concluded on the beneficial effects of hemp seed cake on the fatty acid composition of egg yolk. In Pakistan, supplementation of layer diets with 25% hemp seeds decreased egg yolk total cholesterol, and the content in monounsaturated fatty acids, while total and individual polyunsaturated fatty acids as well as omega-3 and omega-6 fatty acids increased significantly (Shahid et al., 2015). In Canada, feeding laying hens with up to 20% cold-pressed hemp seed meal had no effect on egg production, feed consumption, feed efficiency, body weight change or egg quality. Increasing dietary inclusion of hemp seed meal produced eggs with lower concentrations of palmitic acid and higher concentrations of linoleic and alpha-linolenic acids (Silversides et al., 2005). Likewise, the inclusion of hemp seeds in the diets of laying hens up to a maximum level of 20% did not adversely affect performance and resulted in the enrichment of the n-3 fatty acid content of eggs (Gakhar et al., 2012). In Germany, a trial with laying hens concluded that compound feeds with up to 10% hemp seed cake did not negatively influence laying performance but enriched yolk fat with n-3 polyunsaturated fatty acids (Halle et al., 2013).