This study aimed to evaluate the impact of the use of chemically treated tropical forage in nutritional profile of bovine milk. We evaluated four cane sugar silages: without additive (control); with 1% urea; with 0.5% urea + 0.5% calcium oxide (CaO); with 1% CaO, with base on natural matter, the feeding of dairy cows. There was no difference in the physical‐chemical milk characteristics. The sum of polyunsaturated fatty acids (PUFA) was higher for diet with sugar cane silage with 1% CaO. The activity of the enzyme Δ9‐desaturase in the mammary gland was greatest for myristoleic acid (C14:1 c9) and palmitoleic acid (C16:1 c9) with the diet with sugar cane silage with 1% urea. Among the evaluated diets, the best one was that used 1% CaO in sugar cane silage because it provided higher proportions of PUFA, Omega‐3 fatty acids and conjugated linoleic acid and its isomers. Practical Applications There is considerable interest in altering the fatty acid composition of milk with the overall aim of improving the long‐term health of consumers. In general, milk fat synthesis directly responds to changes in ruminal fermentation pattern, given that in this process both precursors and metabolites of regulatory synthesis in the mammary gland are produced. The use of additives in the diet also changes the pattern of rumen fermentation and consequently the fat synthesis in milk. There are very few studies that seek to evaluate the effect of additives in the ensiling process on rumen environment and milk characteristics. More than that, study the safety and quality of the product for consumers.

Preservation of sugarcane silage with urea and calcium oxide: performance and metabolic efficiency of dairy cowsThis unedited manuscript has been accepted by RCCP for future publication and is provisionally published on our website. The manuscript will undergo copyediting, typesetting, and galley review before final publication. Please note that this advance version may differ from the "Ahead of print" and also from the final version. Preservation of sugarcane silage with urea and calcium oxide: performance and metabolic efficiency of dairy cows Conservación del ensilaje de caña de azúcar con urea y óxido de calcio: rendimiento y eficiencia metabólica en vacas lecherasPreservação da silagem de cana-de-açúcar com ureia e óxido de cálcio: desempenho e eficiência metabólica de vacas leiteiras