Intake and digestibility are key drivers of animal production from grazed forage. The objective of this study was to compare the in vivo digestibility and voluntary dry matter (DM) intake of grass-only and grass-white clover (grass-clover) forage in individually housed sheep. This study was a Latin square design, repeated on three occasions in 2017: Spring (27 March-29 April), summer (19 June-22 July) and autumn (4 September-29 September). Grass-clover and grass-only swards were harvested daily and offered ad libitum to 6 individually housed wether sheep per treatment per period. Digestibility of DM, organic matter (OM), neutral detergent fibre (NDF) and acid detergent fibre (ADF) were determined using the total faecal collection method. Dry matter intake was not significantly different between treatments. White clover inclusion increased forage crude protein concentration in autumn (p < 0.001) and reduced NDF concentration in the offered forage (p < 0.001), increasing nitrogen intake per sheep in autumn (p < 0.001) and decreasing NDF intake per sheep in autumn (p < 0.001). Grass-clover swards had a significantly greater OM and DM digestibility compared to grass-only swards (p < 0.05). This could potentially result in increased animal production from grass-clover swards compared to grass-only swards.
Keywords: Lolium perenne; Trifolium repens; digestibility; season; sheep.