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The inclusion of companion forages in the diet of ruminant animals is gaining popularity in temperate regions due to observed improvements in animal performance. The aim of this study was to assess the effect of diet type on DM intake (DMI) and organic matter digestibility (OMD) in sheep. Furthermore, the effect of sward type on diet nutritive quality was investigated. Five dietary treatments were investigated using a 5 x 5 Latin square design experiment: Perennial ryegrass (Lolium perenne L.; PRG) only or PRG plus white clover (Trifolium repens L.;PRG+WC), red clover (Trifolium pratense L.; PRG+RC), chicory (Chicorium intybus L.; PRG+Chic) or plantain (Plantago lanceolata L.; PRG+Plan) at a ratio of 75 % PRG and 25 % of the respective companion forage and 100 % PRG for the grass only treatment on a DM basis. Twenty Belclare castrated male (wether) sheep were housed in metabolism crates across five feeding periods. Individual DMI and faeces output were recorded daily and digestibility parameters subsequently calculated. Results show that the inclusion of any companion forage increased DMI (kg/day DM) which ranged from 1.55 ± 0.038 (PRG) to 1.76 ± 0.038 (PRG+Chic) (P < 0.001). The PRG+WC (825 ± 1.1) , PRG+RC (823 ± 1.1) and PRG+Chic (826 ± 1.1) diets had a greater in vitro OMD (g/kg DM) when compared to PRG (819 ± 1.1) or PRG+Plan (816 ± 1.1) (P < 0.001). Furthermore, the PRG+Chic (830 ± 2.9) diet had a greater in vivo OMD (g/kg DM) (P < 0.01) when compared to the PRG, PRG+RC, and PRG+Plan diets. Regression analysis showed that in vitro estimates moderately reflected in vivo measurements (r2 = 0.61). The inclusion of any companion forage increased dietary CP content and reduced the proportion of NDF in the diet. Crude protein concentration increased by an average of 16.5 g/kg DM and NDF content was reduced by 25.3 g/kg DM, on average, with companion forage inclusion (P < 0.001). Results suggest that binary sward mixtures benefit pasture based sheep production systems boosting sward quality and aiding increased DM intakes of a more digestible diet.
Woodmartin et al. (Wed,) studied this question.