The effect of adding an enzyme containing lactic acid bacterial inoculant to big round bale oat silage on intake, milk production and milk composition of Jersey cows

Ensiling of whole crop oats in wrapped big round bales is common in South Africa. Low numbers of homofermentative lactic acid bacteria present on whole crop oats prior to ensiling, as well as a low water soluble carbohydrate content, may have a detrimental effect on preservation of whole crop big bale oat silage. The aim of this study was to determine the effect of addition of an enzyme containing lactic acid bacterial inoculant to big bale oat silage on silage composition, silage intake, milk production, and milk composition of Jersey cows. Oats (Avena sativa, cv Cederberg), was planted on 30 April 1998 on 2 ha under dry land conditions in the Western Cape province of South Africa. The crop was cut on 3 September at the bloom stage, wilted and ensiled in big round bales. The inoculant was applied during the baling process on half of the bales. Bales were stored for 9 months, transported to Outeniqua Experimental farm and fed to Jersey cows. The control and inoculated oat silages were well preserved at a pH of 4.56 and 4.52 at a dry matter content of 317 and 328 g/kg silage. The in vitro organic matter digestibility as well as the crude protein, neutral detergent fibre and acid detergent fibre contents were unaffected by inoculant but the inoculated silage tended (P=0.06) to have a lower level of butyric acid. Twenty-two multiparous Jersey cows were blocked into pairs and randomly allocated to control or inoculated silages. Whole crop oat silage was fed ad libitum and dairy concentrate was fed at 5.5 kg DM per cow per day. The intake of control and inoculated oat silage was 11.7 and 12.3 kg DM per cow per day (P=0.09), respectively. Milk production of the cows fed the inoculated silage was 17.7 kg per cow per day compared to the 16.7 kg per cow per day for cows fed the control silage (P=0.05). Cows fed the inoculated silage had lower (P=0.01) milk urea nitrogen. Addition of the inoculant to big bale oat silage increased silage intake and milk production of Jersey cows.