Trial reveals benefits of companion grasses

A new study has shown good potential to improve animal performance by incorporating clover and herbs in ryegrass swards, with trial lambs consuming up to 14 per cent more dry matter (DM). Debbie James reports. The animal and grassland research team at Irish farm research body Teagasc studied the effect of sward type on dry matter (DM) intake, digestibility and methane production in sheep. That study has now concluded and the results show that lambs consuming perennial ryegrass combined with white and red clover or chicory consumed between 11-14 per cent more DM than those grazing perennial ryegrass only.Fiona McGovern, the projects lead researcher, says the results indicate that sheep DM intake is positively influenced by the inclusion of companion forages, both clover and herbs.She adds this partially explains their role in improving animal performance.Selective Sheep are selective grazers and adding anything different in their diet will generally encourage higher intakes if it is palatable, says Dr McGovern.These forages have a higher percentage of leaf compared to ryegrass, making them a more appealing feed.The trial involved 20 Belclare wether hoggets weighing an average of 65kg liveweight and five dietary treatments perennial ryegrass only, perennial ryegrass with white clover, perennial ryegrass with red clover, perennial ryegrass with chicory and perennial ryegrass with plantain. There were four animals in each feeding group and data was gathered over five feeding periods. All diets were formulated on a DM basis at a ratio of 75 per cent perennial ryegrass and 25 per cent of the companion forage. This was based on field studies ongoing at Teagasc Athenry with the proportion of forage included representing forage inclusion levels in the grazing experiments, says Dr McGovern.Importantly, in this study animals were housed in metabolism crates to facilitate intake and digestibility measurements with herbage harvested each morning, and the specific dietary allocations offered to sheep as zero grazed herbage. The DM digestibility ranged from 793g/kg DM in the perennial ryegrass -only and perennial ryegrass with red clover to 804g/kg DM in the perennial ryegrass with chicory.This, says Dr McGovern, was largely similar across treatments. FreshThe forage was cut fresh and any that was uneaten after a feeding period was removed and weighed.Animals were always offered 10 per cent over and above what they were expected to eat.As animals were offered an ad-lib level of feed, any dietary refusals were examined with consistently more perennial ryegrass refused in comparison to the forage portion of the offered diet, says Dr McGovern. The inclusion of companion forages alongside perennial ryegrass in the grazed sward can increase the nutritive value and biodiversity of the sward, heighten an animals motivation to eat and give the potential toproduce greater dry matter yields from a lower chemical nitrogen input. The study also investigated the impact of including companion forages on enteric emissions.There was a 12 per cent reduction in methane output in animals consuming the swards with the clovers and plantain included compared to the perennial ryegrass -only and ryegrass with chicory swards.This is under further investigation but at present is a positive outcome potentially leading additional mitigation strategies for pasture-based production systems, says Dr McGovern.