Nutrient assessment of sea buckthorn residues as potential feed ingredients

This study aimed to evaluate the suitability of sea buckthorn by-products, including pomace without seeds (SBPW), pomace with seeds (SBPS), and leaves (SBL) as potential livestock feed ingredients. Proximate composition, amino acids, fatty acids, minerals, vitamins, and metabolizable energy (ME) were assessed and compared to the daily requirements of livestock, assuming an inclusion rate of 2.5% of dry matter intake in different animal species. SBPW exhibited the highest metabolizable energy (13.7-17 MJ/kg DM across species), exceeding 2.5% of daily requirements in most animal species, suggesting it is a good energy source, whereas SBL contributed the least (8.1-13.6 MJ/kg DM across species). SBL was mineral rich, with notably elevated Fe, Ca, Mg, and Mn concentrations, supporting its use as a mineral supplement, whereas both pomaces contained low mineral levels. SBL and especially SBPS revealed promising amino acid profiles, showing potential as protein source, meeting 2.5% daily amino acid requirements across most categories, especially gilts and pregnant sows. SBPS contained high levels of arginine (31.4 g/kg DM) and lysine (11.3 g/kg DM), while SBL also supplied substantial amounts of essential amino acids (e.g., lysine 10.2 g/kg DM). Sulfur-containing amino acids were limiting in all residues, with methionine especially low (e.g., SBPW 0.9 g/kg DM). SBPW provided insufficient essential amino acids for most categories, suggesting it would have to be combined with protein feeds to achieve a balanced ration. SBPS was rich in polyunsaturated (notably alpha-linolenic: 1.39 g/kg DM) fatty acids, while SBPW contained more monounsaturated and SBL more saturated fats. Both pomaces provided similar linoleic acid (≈2.5 g/kg DM), exceeding pig but not poultry requirements at 2.5% dry matter intake. All residues were rich in vitamin E, particularly SBPW (720 mg/kg DM), and pomaces contained substantial β-carotene (SBPW 258 mg/kg DM, SBPS 151 mg/kg DM), with potential benefits for gestating animals and those experiencing high oxidative stress. Overall, this study provides an initial assessment of sea buckthorn residues as alternative feed resources and offers guidance for their strategic inclusion in animal diets supporting more sustainable, circular feeding systems.