Agroscope Liebefeld-Posieux Research Station ALP, rte de la Tioleyre 4, 1725 Posieux

A close look at the butyric acid bacterial spores in silages and moist hay

The guidelines of different traditional Swiss semi hard and hard cheeses prohibit to feed conserved forage containing more than 18 % water to dairy cows. In two trials, the butyric acid bacterial content of the forage, faeces and milk of cattle fed with moist hay and silages was investigated. In the first trial, silages with 38 and 53 % dry matter as well as ventilated hay were produced from the same original material. In the second trial, moist hay was treated with propionic acid and ventilated hay was produced as a comparison. On average, the moist hay had a DM content of 80 % when baled and 84 % when fed. The different forages were fed to dairy cows for three weeks. Feed, faeces and milk samples were taken at regular intervals to determine the number of butyric acid bacterial spores. In the third week of the trial, hard cheese was made on two days. The forage had low contents of butyric acid bacterial spores. The milk of the cows fed with grass silage or moist hay exhibited slightly higher spores content than that of those fed with ventilated hay. However, no problems occurred during cheese making.

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