Effect of increasing corn silage inclusion in finishing diets cattle with or without tylosin on performance and liver abscesses.

Abstract

A pooled analysis was performed to evaluate whether corn silage fed at 15% or 45% of diet DM impacted liver abscesses prevalence at slaughter in five previous experiments. Cattle fed 15% corn silage had 7.8% abscessed livers compared to 4.1% for cattle fed 45% corn silage when all diets contained tylosin. While improved due to increased corn silage inclusion, the objective of the current finishing study was to determine the impact of silage inclusion in finishing diets with and without tylosin on performance and incidence of abscessed livers in beef cattle. A total of 640 (BW = 334 ± 25 kg) steers were used in a generalized randomized block design with a 2 × 2 factorial treatment design. Treatments included two concentrations of corn silage (15% and 45% of diet DM), with or without tylosin for liver abscesses. This study used 32 pens of cattle with 20 steers per pen and 8 pens per treatment. There was a tendency for an interaction for feed efficiency (G:F; P = 0.10) where cattle fed 15% corn silage had a 2% increase in G:F when tylosin was added to the diet, but no improvements in G:F were observed when tylosin was added to diets containing 45% silage. There was an interaction between silage and tylosin inclusion for abscessed livers (P = 0.05). Cattle fed 15% corn silage without tylosin had the greatest incidence of abscessed livers (34.5%) compared to other treatments (P = 0.05), and the incidence of abscessed livers was decreased to 19% if tylosin was fed with 15% corn silage. Feeding 45% silage was effective at lowering the incidence of abscessed livers (P = 0.05) which was 12.4%, regardless of whether tylosin was fed. Feeding corn silage at 45% of diet DM (77.5% concentrate) was as effective as feeding tylosin to cattle on a 92.5% concentrate diet. Feeding corn silage at greater inclusions decreased daily gain (P ≤ 0.01) but increased final body weight when fed to an equal fatness (cattle fed 45% CS were fed 28 d longer). Feeding corn silage at 45% was more economical compared to feeding 15% corn silage, especially as corn prices increase, provided shrink is well managed. Feeding elevated concentrations of corn silage may be an economically viable method to reduce incidence of liver abscesses without antibiotic use for smaller operations that can manage more corn silage in finishing diets.