Effects of storage temperature on silage nutrient composition, fermentation profile, and aerobic stability through a...

Silage is a major component of dairy diets worldwide, but the effects of storage temperature (ST) on the nutrient composition, fermentation profile, and aerobic stability of silage remain unclear. Our objectives were to (1) evaluate the effects of storage temperature on nutritive value and fermentation profile of silage, and (2) assess the effects of ST on nutritive value, fermentation profile, and aerobic stability of whole-plant corn silage (WPCS). Data from 42 peer-reviewed articles met the selection criteria, with a total of 253 treatment means. For WPCS, a secondary meta-analysis with data from 15 articles met the selection criteria, with a total of 96 treatment means. Silage was classified by type, storage length, and temperature range. Storage temperatures were categorized into 10°C increments: (1) ≤10°C; (2) >10 and ≤20°C; (3) >20 and ≤30°C; (4) >30 and ≤40°C; and (5) >40°C. Data were analyzed using a mixed-effects model with ST as a fixed effect and treatment (other than ST) within study as a random effect. Both storage length and silage type were fitted as continuous and categorical covariates in the model, respectively. For the WPCS subset, silage type classification was not included in the model. The pooled SEM for response variables per study was included as a weighting factor for the data and calculated as the inverse of the square of the variance. Means were determined using the LSMEANS statement in SAS 9.4 and were compared using the sequentially rejective Bonferroni t-test adjustment. Increasing ST impaired silage fermentation by reducing lactic acid bacteria (LAB) counts. Conversely, lower temperatures (≤10°C) restricted silage fermentation due to lower acid production and altered metabolic activity of LAB. For WPCS, increasing ST gradually increased DM losses, and greater ethanol production was observed for silage stored at 11°C to 20°C than at 31°C to 40°C. Overall, moderate temperatures (21°C to 30°C) may be more suitable for silage storage due to greater acid production, rapid pH decline, and lower DM losses. In addition, changes in fermentation profile across ST ranges indicate a potential shift in dominant bacterial species during ensiling. These findings can provide useful information about silage production for dairy farmers. In cold climates, producers should allow longer storage times to ensure adequate fermentation, and the use of inoculants capable of stimulating fermentation at low temperatures may provide additional benefits. Conversely, in warm or tropical regions, rapid silo sealing and careful face management are important to prevent excessive heating and nutrient losses during feed-out.