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- Vaga, Merko, et al.
(författare)
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Effects of heat treatment on protein feeds evaluated in vitro utilizing the method utilizable protein
- 2014
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Ingår i: Rapport / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård. - 0347-9838. ; , s. 157-162
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study was to evaluate effects of heat treatments on protein feeds for dairy cows utilising the in vitro method utilisable protein (uCP) using three protein feeds, field beans (Vicia faba), lupines (Lupinus albus) and peas (Pisum sativum). All the feeds in the study were grinded (1 mm sieve) and the three protein feeds were autoclaved with steam at increasing temperatures (105, 120 and 135°C) or dry oven-heated (120, 140 and 160°C) at increasing intervals (30, 60 and 90 min). The feeds (heat treated and untreated as a control) were incubated in vitro as components in complete diets for dairy cows utilising the method uCP. All diets were isonitrogenous with concentrations of 18% crude protein (CP) on dry matter (DM) basis. The diets consisted of grass silage (50% of DM) and varying proportions of barley (Hordeum vulgare) and protein feeds depending on the CP concentrations. The complete diets were incubated in buffered rumen fluid and the concentration uCP was calculated based on ammonia nitrogen measurements at different intervals in the liquid of the in vitro vessels. The gas productions during the fermentation in vitro were continuously recorded by an automatic system. The two methods for heat treatments, autoclaving with steam and dry oven-heating at medium and high levels were effective methods to increase the uCP concentrations. However, low heating temperatures decreased uCP concentrations for the pea diets and had no significant effect for the diets with lupines. Short exposure time (30 min) at the highest temperature in the autoclave increased uCP concentrations for the diets with field beans by 31%, lupines by 10% and peas by 7%, whereas the same time in the dry oven treatment decreased uCP concentrations by 10%, 14.% and 12%, respectively. Increasing the heat exposure time from 60 to 90 minutes at the highest treatment levels did not have any improving effects, except for the diets with the oven-treated peas. However at medium temperatures there was significant increase of the uCP concentrations for all evaluated diets. It was concluded heat treatment will affect the concentrations of uCP in dairy cow diets but the responses in animal production needs to be evaluated by production trials.
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