Use of maize silage in beef cattle feeding during the finishing period

摘要

The research investigated the use of maize silage (MS) in beef cattle diets during the finishing period by monitoring a sample of 406 commercial farms located in the Po Valley, Farms were selected in order to cover the most diverse rearing situations,in terms of farm size and cattle genotype, in which MS was fed to beef cattle during the finishing period. Each farm was visited to collect information about the feeding regimen and representative samples of total mixed ration (TMR) and MS were collected for chemical and physical analysis. Two specific classification factors of the farm population were created for statistical analysis of experimental data. The former considered the quantity of MS included in the TMR and the latter was based on the content of long particles of MS (>13 mm). Regardless of chop length, the quality of MS population was satisfactory both by a nutritional and a preservation standpoint, as indicated by the dry matter (DM) (350 +- 38 g/kg of fresh weight) and the high starch content (310 +- 28 g/kg DM) and lactic acid concentration (49 +- 12 g/kg DM). Physical analysis of MS samples showed a wide range of particle size, as result of the different chopping lengths during harvest. The average content of long particles retainedby a 13-mm screen was 143 +- 73 g/kg of fresh weight. On average, MS accounted for 33.4% to the total dietary DM but a large standard deviation (11.4%) was observed across farms. The decision about the amount of MS to be included in the TMR has shown tobe independent on both chemical composition and particle size of the roughage. In diets with a high quantity of MS the risk of occurrence of rumen acidosis due to the additional starch brought by this silage is balanced either by a significant reductionin the amount of other starch sources or by the higher NDF content and the coarser size of the dietary particles which should promote a prolonged rumination. The analysis of TMR particle size showed that in more than 30% of the farms MS was damaged during diet preparation with a loss of long particles. A logistic analysis demonstrated that the relative risk of MS damage was significantly increased either by a larger inclusion of the roughage in the TMR or by the use of silage with coarse particles.