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Effects of heat treatment on protein feeds evaluated in vitro by the method of estimating utilisable crude protein at the duodenum
Author(s) -
Vaga M.,
Hetta M.,
Huhtanen P.
Publication year - 2017
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1111/jpn.12646
Subject(s) - duodenum , in vitro , protein digestibility , chemistry , biochemistry , chromatography , food science , medicine
Summary The effect of heat treatment on the protein value of field beans, lupins and peas was studied using an in vitro method. Protein feeds were subjected to heat treatment for 30, 60 and 90 min in forced air oven at 120, 140 and 160 °C and in autoclave at 105, 120 and 135 °C. The heat‐treated protein feeds were incubated in buffered rumen fluid together with grass silage and barley in complete isonitrogenous diets. The gas production ( GP ) was recorded continuously, and ammonia‐N ( NH 3 ‐N) concentrations were determined during the in vitro incubation at 8, 24 and 48 h and used to determine the utilisable crude protein (u CP ) at the duodenum at 16 h of incubation ( uCP 16 ). Heat treatments decreased the concentration of soluble crude protein and increased neutral detergent insoluble CP ( NDICP ) in all protein feeds compared to untreated. Inclusion of protein feeds to basal diet showed no increase in the uCP 16 in untreated field bean diet and only a small numerical increase in the uCP 16 concentrations from 160 g/kg dry matter ( DM ) to 166 and 172 g/kg DM in untreated lupine and pea diets, respectively, indicating high degradability of untreated feeds. Increasing the time and temperature of the heat treatment linearly increased the uCP 16 concentrations in field bean and pea diets, but not in lupin diets. Autoclave treatment was more effective in decreasing uCP 16 than oven treatment despite the lower temperatures used. However, the combination of highest temperatures and treatment time in autoclave increased acid detergent insoluble CP ( ADICP ) concentrations in protein feeds, indicating protein damage and decreased intestinal digestibility. Determining in vitro uCP and ADICP shows to be a promising method for evaluating protein value in heat‐treated animal feeds.