Alfa-tocopherol and beta-carotene in roughages and milk in organic dairy herds.

摘要

The aim of the present on-farm study was to analyse vitamin content in roughage at harvest and during storage and to analyze milk vitamin content when feeding the roughage to dairy cows. Roughages produced at five organic dairy farms were monitored at harvest and several times during winter as stored silage. As an average of several sampling times, roughage alpha-tocopherol and beta-carotene contents (mg per kg DM) during the period when the roughage was fed were, respectively, 30 and 21 in grass-clover silage, 13 and 8 in maize wholecrop silage and 28 and 9 in cereal wholecrop silage. Daily intake of alpha-tocopherol was 876 mg per cow-431 mg from roughages, 89 mg from concentrates and 356 mg from a vitamin supplement. Milk yield was 25.9 kg energy-corrected milk (ECM) per cow per day with alpha-tocopherol and beta-carotene contents ( mug/ml) of 0.82 and 0.17. The study additionally showed the following tendency, but due to few observations no final conclusions could be drawn: For grass-clover silage there were generally no losses of vitamins during the ensiling process and during storage, but there were huge variations between farms. For wholecrop silage there was a loss of vitamins during the ensiling process, whereas there were no further losses during the feeding period. The output of vitamins in milk was within farm positively correlated to supply of vitamins from roughage