Hempseed By-Product in Diets of Italian Simmental Cull Dairy Cows and Its Effects on Animal Performance and Meat Quality

SIMPLE SUMMARY: At the end of their productive career, dairy cows are culled without a fattening period and, therefore, sold at a low market price. On the other hand, the cultivation of hemp (Cannabis sativa L.) is increasing, and hempseed cake is a by-product obtained during the mechanical extraction of the seed. Hempseed cake is rich in polyunsaturated fatty acids, so its use in the diets of cull cows could probably improve meat value and contribute to pursuing the objectives of a circular economy. In this study, hempseed cake was added to the diets of culls cows for the first time with the aim to assess its effect on animal performance and meat quality. The results of the present paper suggest that hempseed cake did not affect animal performance and the characteristics or the fatty acids profile of the meat. From this point of view, although no improvement in the level of unsaturated fatty acids in meat was found, this study showed that hempseed cake can replace soybean meal, thus improving the circular economy. ABSTRACT: Cull dairy cows are important contributors to total beef production in the USA and in Europe. Hempseed cake is a by-product of oil production and it is rich in unsaturated fatty acids (FA). This study aimed to investigate the effect of adding hempseed cake to the diet of Italian Simmental (IS) cull dairy cows on performances and meat quality. Twenty-six cull dairy cows were divided into three dietary groups: hay-based, corn silage-based and pasture-based diets. Within each group, the animals were equally divided into two treatments according to the protein source of the concentrate: hempseed cake (HEMP) or soybeans meal (SB). The trial lasted four months. HEMP showed similar in vivo performance and carcass characteristics, such as average daily gain (p > 0.05) and dressing percentage (p > 0.05), compared with SB. Meat characteristics, such as ether extract content and Warner–Bratzler shear force, were also similar between experimental groups (p > 0.05). Considering FA composition, HEMP showed similar saturated FA and polyunsaturated FA content (p > 0.05) but lower desirable fatty acids (p < 0.05) content and a tendentially lower hypocholesterolemic/hypercholesterolemic ratio (p < 0.10) than SFA. Hempseed cake can substitute soybean in the diet of cull dairy cows without effects on performance or meat quality.