Biodegradation kinetics by microorganisms, enzymatic biodigestion, and fractionation of protein in seeds of cool-climate-adapted oats: Comparison among oat varieties, between milling-type and feed-type oats, and with barley grain

Abstract

Recently, cool-climate-adapted varieties of oats as well as milling-type and feed-type of oats have been developed. The objectives of this study were to determine biodegradation kinetics, enzymatic biodigestion, fractionation and intrinsic structure in seeds of oat varieties; compare among oat varieties and between milling-and feed-type; and reveal an interactive association among structure and nutrition in these seeds. The three oat varieties were CDC Nasser, which is a feed-type, CDC Arborg and CDC Ruffian, which are milling-types of oats. CDC Austenson barley, which is a feed-type of barley grain, was used as a control. The seed samples for each variety grown at University Crop Research Fields were obtained from Crop Development Center (CDC). The Attenuated total reflection - Fourier transform infrared (ATR-FTIR) spectroscopy was used to reveal intrinsic structural profiles of these seeds. The results showed that different varieties had significant differences in chemical and nutrient profiles, biodegradation kinetics and intestinal digestibility (P < 0.05). Nasser oat, which was bred to possess a higher oil content and lower lignin hull, had a higher energy value compared to other varieties of oat. Nasser oat also showed similar values of digestible energy (DE), metabolizable energy (ME), net energy for maintenance (NEm), net energy for gain (NEg) and net energy for lactation (NEL) to Austenson barley grain. Austenson barley seeds showed higher (P < 0.05) rumen undegraded protein (BCP) and had an increased biodegradation ratio of available N to energy (ED_N/ED_OM) during longer incubation periods. Uni- and multi-variate (PCA) analyses were applied to reveal structural features. The PCA analysis did not distinguish between Nasser (feed-type) and Ruffian (milling-type) in the amide region. Significant relationship was revealed between protein molecular structures and protein biodegradation kinetics. In conclusion, Nasser oat (feed-type oat grain) is a promising variety with high fat and low hull content which could be used to replace barley grain in ruminant livestock diets.