Effects of ensilage of grass on performance and nutrient utilization by dairy cattle 1. Food intake and milk production

Abstract

AbstractTwelve lactatiug dairy cows were offered either fresh grass (G) or grass silage prepared from the same pasture which had undergone either an extensive (E) or restricted (R) fermentation, in a three-period change-over design experiment. Ensilage resulted in a reduction in forage pH and water-soluble carbohydrate concentration and an increase in ammonia-nitrogen concentration. The ensiling techniques used ensured that both silages were well preserved with pH values for E and R of 3.81 and 4.08 respectively, while the respective lactic acid concentrations were 124.6 and 27.0 g/kg dry matter respectively. Whilst there were no significant differences in dry-matter intake between treatments, when corrected for losses of volatile compounds, animals offered silage with a restricted fermentation consumed their food at a higher rate of intake (P < 0.001) than did animals on the other treatments. It was also found that while there was no significant difference in milk yield between animals offered fresh or ensiled forage, both butterfat and protein concentration and yields of butterfat were significantly higher (P < 0.01 or greater) with grass and restricted fermented silage than with extensively fermented silage. Ensiling of herbage had no significant effect on apparent digestibility. It is concluded that ensiling of herbage per se had little effect on overall animal performance but pattern of silage fermentation resulted in alterations in milk composition.