The effects of silage feeding on some sensory and health attributes of cow’s milk: A review

Silage has been the prevailing type of preserved forage for cattle feeding in many countries. Carry-over of some components from silage to cow’s milk has been thus of concern. Silage is a richer source of available provitamins A, other carotenoids and tocopherols than hay due to higher losses of these compounds during forage field-drying and hay storage. Ensiled grasses and legume forages contain higher levels of carotenoids and tocopherols than maize silage. Numerous terpenes are carried-over to milk and cheeses from grazed multifloral pastures or from hay, while silages are a poorer source of these flavour-affecting compounds. Data on alcohols, acids, esters, aldehydes and ketones in silage and especially information on their carry-over to milk are insufficient. Milk can gain a bad smell from a stable atmosphere if silage, particularly of poor quality, is fed. Red clover silage feeding can cause considerable levels of estrogenic equol in milk. Deoxynivalenol and zearalenone are the main mycotoxins formed in silage. Their content is reduced by the activity of both some lactic acid bacteria in silage and rumen microflora. The excretion of the mycotoxins in milk is generally low. Silages can be a pool of the undesirable bacteria Bacillus cereus, Clostridium tyrobutyricum and Listeria monocytogenes. Milk contamination with these bacteria can be decreased by the prevention of silage deacidification following air access, and by improving the dairy farm environment, cow hygiene and by sanitary milk harvesting.