Perfil de ácidos graxos, estabilidade oxidativa e aspectos sensoriais do leite de vacas suplementadas com óleo de linhaça na dieta e selenito de sódio injetável

Abstract

The objective of the present work was to evaluate the effect of dietary linseed oil with or without injection of sodium selenite upon fatty acid profile and oxidative stability of milk from dairy cows as well as the acceptance of the milk and the increasing order of preference by the evaluators. Chapter 1 describes the experiment where fourteen cows were allocated into four treatments: Group 1 which received daily 400 mL of linseed oil (LIN); Group 2, 400 mL of linseed oil + 0.2 mg/BW sodium selenite IM (LINSe); Group 3, untreated controls (C). The oil was supplied daily after 15 days of de single application of sodium selenite. Treatments lasted 4 weeks. Linseed oil supplemented animals produced milk with higher levels of conjugated linoleic acid and omega 3 but also more susceptible to oxidation. The application of sodium selenite was effective to prevent premature oxidation of milk. Chapter 2 describes the acceptance and increasing order of preference by the evaluators. The evaluators were not able to identify differences in color, odor and flavor among samples of milk from treated and control groups in relation to a known standard. The inclusion of linseed oil on the cows diet promotes and increase in CLA and omega 3 in milk, which in turn becomes more susceptible to oxidation, requiring the use of antioxidants. Even though causing biochemicals alterations, the addition of 400 mL daily of linseed oil in the diet of dairy cows is not capable of causing sensory changes in milk.