Moist and dry heating-induced changes in protein molecular structure, protein subfractions, and nutrient profiles in camelina seeds.
The objectives of the present study were to investigate the nutritive value of camelina seeds (Camelina sativa L. Crantz) in ruminant nutrition and to use molecular spectroscopy as a novel technique to quantify the heat-induced changes in protein molecular structures in relation to protein digestive behavior in the rumen and intestine of dairy cattle. In this study, camelina seeds were used as a model for feed protein. The seeds were kept as raw (control) or heated in an autoclave (moist heating) or in an air-draft oven (dry heating) at 120°C for 60 min. The parameters evaluated were (1) chemical profiles, (2) Cornell Net Protein and Carbohydrate System protein subfractions, (3) nutrient digestibilities and estimated energy values, (4) in situ rumen degradation and intestinal digestibility, and (5) protein molecular structures. Compared with raw seeds, moist heating markedly decreased (52.73 to 20.41%) the content of soluble protein and increased (2.00 to 9.01%) the content of neutral detergent insoluble protein in total crude protein (CP). Subsequently, the rapidly degradable Cornell Net Protein and Carbohydrate System CP fraction markedly decreased (45.06 to 16.69% CP), with a concomitant increase in the intermediately degradable (45.28 to 74.02% CP) and slowly degradable (1.13 to 8.02% CP) fractions, demonstrating a decrease in overall protein degradability in the rumen. The in situ rumen incubation study revealed that moist heating decreased (75.45 to 57.92%) rumen-degradable protein and increased (43.90 to 82.95%) intestinal digestibility of rumen-undegradable protein. The molecular spectroscopy study revealed that moist heating increased the amide I-to-amide II ratio and decreased α-helix and α-helix-to-β-sheet ratio. In contrast, dry heating did not significantly change CP solubility, rumen degradability, intestinal digestibility, and protein molecular structures compared with the raw seeds. Our results indicated that, compared with dry heating, moist heating markedly changed protein chemical profiles, protein subfractions, rumen protein degradability, and intestinal digestibility, which were associated with changes in protein molecular structures (amide I-to-amid II ratio and α-helix-to-β-sheet ratio). Moist heating improved the nutritive value and utilization of protein in camelina seeds compared with dry heating.
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8; Animal Nutrition Institute, Sichuan Agriculture University, Sichuan 625014, China.
Quanhui
Q
Peng
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8.
Nazir A
NA
Khan
Animal Nutrition Institute, Sichuan Agriculture University, Sichuan 625014, China.
Zhisheng
Z
Wang
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5A8; Department of Animal Science, Tianjin Agricultural University, Tianjin 300384, China. Electronic address: Peiqiang.yu@usask.ca.
Peiqiang
P
Yu
D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D019607:Brassicaceae / Q000737:chemistry*; D002417:Cattle; D004063:Digestion; D006358:Hot Temperature; D007413:Intestinal Mucosa / Q000378:metabolism; D015394:Molecular Structure; D009753:Nutritive Value; D010940:Plant Proteins / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012417:Rumen / Q000378:metabolism; D012418:Ruminants / Q000378:metabolism; D012639:Seeds / Q000737:chemistry*
D010940:Plant Proteins
camelina seed; heat processing method; nutrient availability; protein molecular structure