In vitro and in situ evaluation of a diet for bovine cattle added with organic oils

Abstract

Objective: To perform in vitro and in situ evaluation of a diet for dairy cattle with fish oil and soybean oil at different proportions.

Design /methodology /approach: Four treatments with different proportions of fish oil (FO) and soybean oil (SO) were evaluated (Control: no added oil, diet 1: 2% FO, diet 2: 2% FO and 1.5% SO, diet 3: 2% FO and 3% SO). In vitro digestibility and in situ degradability were evaluated. Ammonia nitrogen, lactic acid, volatile fatty acids (VFAs), and microbial protein were determined. For the in situ evaluation, a protein degradability kinetic was carried out. The means were compared by Tukey's test at a 5% confidence level.

Results: The proposed diets increased gas production in in vitro kinetics as the addition of oils increased (p <0.001) and the kinetic latency time decreased (p <0.001). All diets decreased the production of short chain fatty acids (p <0.001), the production of ammonia nitrogen and lactic acid did not differ compared to the control (p <0.05). Diet 3 presented a higher production of propionic acid in comparison to diet 1 and 2. In the in situ kinetic, the "kd" rate increased as the addition of the oils increased.

Study limitations /implications: Although the production in milliliters of  and  increased in all treatments, it is an upsurge proportional to the gas production given by a better use of the diets.

Findings /conclusions: The addition of oils produced changes in the fermentation patterns and in the degradation of the protein at the ruminal level, increasing the bypass protein. Which offers an opportunity to improve performance in certain production situations.