Grazing preference for pasture species by sheep

Abstract

This investigation aimed to evaluate the preferences of sheep for a range of pasture species using species choice trials of living swards, rate of intake experiments with cut fresh herbage and observations of grazing in the field.

Sheep exhibited no specific preference for pure species grown in pots in a very high fertility soil. Sheep were fed fresh cut herbage to examine the rate of intake of 11 pasture species. Leaf was consumed at faster rates (6.9-10.2g DM/min) than pseudostem (4.1-6.3g DM/min) except for cocksfoot leaf which was eaten at a significantly lower rate (4.8g DM/min) than the leaf of all other species. Timothy leaf was consumed at a significantly faster rate (10.2g DM/min) than all other herbage followed by Hakari mountain brome leaf (8.2g DM/min). Chicory and white lover were consumed at significantly higher rates than all other species on a fresh matter basis however the low DM% of these two species resulted in reduced dry matter intake rates of 6.8 and 8.1g DM/min respectively.

Field grazing trials showed dicotyledon species to be preferred over grasses. Preference was measured via the rate of decline in height of five grass species. Roa tall fescue and Maru phalaris were reduced in height at the fastest rate and were preferred over Matua prairie grass which was of intermediate preference. Yatsyn ryegrass and Wana cocksfoot were species of low preference as they were only grazed when preferred species had been reduced to low levels.

Sheep showed strong preference for herbage of high nitrogen content by grazing sites where 300kg N/ha had earlier been applied. This preference for high nitrogen herbage overcame any preference differences between species with all species on high nitrogen sites being grazed to low levels on day one of the seven day grazing duration.

Rate of intake trials showed close correlation with preferences observed in the field and it is strongly suggested that sheep grazing preferred species will have higher intakes and superior liveweight gains than those grazing lower preference species.