PSVIII-4 - Physiochemical and nutrient profile study: Effect of oat varieties and types (feed type vs. milling type)

Abstract: The objective of this project was to assess the impact of four oat varieties and types (feed type vs. milling type) on their physiochemical and nutrient profiles. Four oat varieties (Haymaker, Nasser, Arborg, and Summit) from 3 harvested years (2018, 2019, 2020) were used for chemical analysis, energy profiles and protein and carbohydrate subfractions evaluations following the AOAC standard methods, NRC-2001 model, and CNCPS 6.5 model, respectively. The experiment design was an RCBD design with oat varieties as a fixed effect and harvested year as a random block effect. The MIXED model of SAS 9.4 was used for statistical analysis with significant level declared at P < 0.05 and trends at 0.05≤P < 0.1, and SAS contrasts were used for comparing oat types (feed type vs. milling type). Results showed that Nasser oat had the highest ether extract (EE), and non-protein nitrogen (NPN) value of the four varieties (4.05, and 3.74 %DM, P< 0.01) while the value of crude protein (CP) of Nasser oat was smallest but had a similar CP content with Arborg and Summit oat (14.69, 15.78, and 15.40 %DM). Haymaker oat had the highest CP content among the four varieties (17.57 %DM, P< 0.05). Arborg, Summit and Haymaker oat had similar acid detergent lignin (ADL) in the four oat varieties (3.60, 3.29, and 4.19 %DM), yet had higher ADL content compared to Nasser oat (1.63 %DM, P< 0.01). More importantly, Haymaker oat had higher indigestible neutral detergent fiber at 120 h (iNDF120h, %DM) compared to Summit oat (P < 0.05), and had similar iNDF120h content with Arborg and Nasser oat. There was a significant difference in EE, total CHO, and ADL values between feed type and milling type (P < 0.05). Haymaker oat had the highest truly digestible crude protein (tdCP) among the four oat varieties (17.42 %DM, P< 0.05). Nasser oat also had the highest total digestible nutrients (TDN) and all energy values compared to other three oat varieties (P < 0.05), while Arborg and Summit oat had similar tdCP, TDNs and energy values. In addition, Haymaker oat had higher PA2 (6.62 vs. 5.37 %DM) and PB1 (10.18 vs. 8.72 %DM) than that of Nasser (P < 0.05) although they were the same oat types, and the indigestible fiber fractions (CC) of Nasser oat was lowest among these four varieties (5.04 %CHO or 3.93 %DM, P< 0.05). Haymaker also had higher RDPA2, RDPB1, total RDP, RUPA2, RUPB1, total RUP fractions than that of Nasser oat (P < 0.05). Feed type had relatively higher CP, higher energy values but with lower total CHO contents than milling oat. In conclusion, Nasser oat could be an important source of grain to replace barley in the ration of dairy cattle.