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 yr (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 a randomized compete block 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 greatest ether extract (EE), and non-protein nitrogen (NPN) value of the four varieties [4.05, and 3.74 % dry matter (DM); P < 0.01] while the value of crude protein (CP) of Nasser oat was least but had a similar CP content with Arborg and Summit oat (14.69, 15.78, and 15.40 % DM). Haymaker oat had the greatest 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 greater ADL content compared with Nasser oat (1.63 % DM, P < 0.01). More importantly, Haymaker oat had greater indigestible neutral detergent fiber at 120 h (iNDF120h, % DM) compared with Summit oat (P < 0.05) and had similar iNDF120h content with Arborg and Nasser oat. There was a significant difference in EE, total carbohydrate (C HO), and ADL values between feed type and milling type (P < 0.05). Haymaker oat had the greatest truly digestible crude protein (tdCP) among the four oat varieties (17.42 % DM, P < 0.05). Nasser oat also had the greatest total digestible nutrients (TDN) and all energy values compared with other three oat varieties (P < 0.05), while Arborg and Summit oat had similar tdCP, TDNs and energy values. In addition, Haymaker oat had greater 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 least among these four varieties (5.04 %CHO or 3.93 % DM, P < 0.05). Haymaker also had greater RDPA2, RDPB1, total RDP, RUPA2, RUPB1, total RUP fractions than that of Nasser oat (P < 0.05). Feed type had relatively greater CP, greater energy values but with less 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.