Farm Table says:
Dietary choice and grazing behaviour
What is the problem?
It is identified that sheep choose to eat a mixture of pasture species to:
- provide novelty in their diet
- sample feeds they are not familiar with
- maintain rumen function
- balance carbon and N intake
- regulate energy and protein intake
Plants with a negative taste or texture are avoided. Sheep and cattle tend to consume feed high in fiber with a slow rate of digestive passage at dusk in order to avoid eating during the night when predators may be active.
Offering livestock dietary choice could enable farmers to benefit from the innate ability of sheep to moderate their own diet.
With dietary choice offered through spatially separated pasture arrangements providing additional livestock production benefits relative to conventional seed mixes.
However, improved pasture systems in southern Australia provide little opportunity for livestock to display dietary choice, with pasture systems often comprised of a single sown species or of a simple grass/clover mix. Such pastures limit the ability of sheep to self- select their diet due to lack of choice.
What did the research involve?
The experiment was conducted in Hamilton, Victoria, Australia:
- temperate climate
- long-term average annual rainfall of 686 mm
- rainfall is winter and spring dominant
- summer and early autumn usually being hot and dry
- soils are basalt origin
- tested seven treatments
- replicated four times in a randomized complete block design
- plot sizes of 400–600m long and 16–18m wide
- used lambs born between 3 August and 7 September 2010 sourced from two genotypes
The treatments were:
- 100% perennial ryegrass
- 100% plantain
- 100% lucerne (cv. Stamina GT6)
- 50: 50 perennial ryegrass/plantain
- 50: 50 perennial ryegrass/ lucerne
- 50: 50 plantain/lucerne
- 33 : 33 : 33 perennial ryegrass/plantain/lucerne
The multiple species swards used the same cultivars as the single species swards.
What were the key findings?
When faced with a choice of pasture types, livestock consume a mixed diet, even though any one of the pasture species available could supply the animal with its nutritional needs.
Understanding animal grazing preferences and voluntary intake for different forage species could assist farmers when designing pasture systems to maximise livestock and sward performance.
The data presented in this paper has provided support for the hypothesis, showing that when lambs are offered dietary choice through the use of spatially separated pasture species, they exhibit clear preferences between pasture species.
These preferences have been demonstrated in spite of any one of the pasture species provided is sufficient to meet the nutritional requirements of the lambs.