Use of Italian Ryegrass to Improve Meat Production on Yorke Peninsula, SA.

Summary

The Yorke Peninsula (YP) of South Australia (SA) is a medium to low rainfall cropping district (375 – 480mm average annual rainfall) with minimal livestock production. An average enterprise in the area is either continuos cropping or 90 to 95% cropping and 5 to 10% pasture / livestock production. Common pastures species for the area include cereals or legumes (i.e. medics or clovers), however it is recognised that fast winter growing species that provide large quantities of high quality vegetation early and continuously through out the growing season would best suit this farming system. In the higher rainfall areas of South Australia Italian ryegrass species have proven to be important pasture species in livestock production, providing early growth (ready to graze approximately 6 weeks after seeding) that responds to high stocking pressure when rotationally grazed. There has been limited use of the Italian ryegrass in lower rainfall areas of the state particularly in cropping systems. The project was initiated by several livestock producers of the Arthurton Agricultural Bureau who whished to determine the suitability of Italian ryegrass to their farming system & environment.

The overall objective of the project was to determine the suitability of Italian ryegrass as a pasture species in a typical York Peninsula farming system (i.e.90% cropping, 10% livestock). Initially it was felt this would be best done by using two groups of animals that would graze a control plot and a Italian ryegrass plot. The final lamb weights along with other measurements of pasture and environment sustainability would determine the success of Italian ryegrass in this system. However while the overall objective remained constant, the focused shifted from analysing livestock production (i.e. final lamb weights and condition scores) to focussing on pasture production i.e. growth, grazing days and using this to determine gross margins for the treatments and the suitability of Italian ryegrass to the YP. Increasing producer knowledge on grazing management and assessing environmental factors to determine sustainability of system were also final objectives of the project.

The project was conducted at Maitland on a property typical of the district. One 56ha paddock assigned to pasture for the 2005/2006 season was planted to cereal, medic and clover (typical pasture mix for the area). Post seeding the area was slipt into 4 16ha paddocks and one section over sown with the Italian ryegrass varieties Tetila & Winter Star. Two mobs of merino ewes, mob 1 & mob 2 were used to graze the ryegrass and control pastures respectively. Merino hogget’s and Hereford calves were also used on the ryegrass pasture to increase stocking pressure. Pasture quality (energy, protein, % DM), pasture quantity (kg/Dm available, growth rates), sustainability measures (ground cover, proportion of productive species, soil surface, percentage plant litter) and livestock production (ewe faecal worm egg counts, ewe & lamb weights and condition scores, stocking rates, gross margins) were all measured at various intervals across the project.

Livestock production and sustainability data showed little difference between the Italian ryegrass pasture and the traditional pasture (control). However stocking rates and pasture growth of the ryegrass pasture was considerably higher than that of the control (in some instances 4 times greater). This result however may be more attributable to the grazing management (rotational verus continuous) than the species composition. When comparing income between treatment groups the ryegrass pasture was up to $151/ha higher than the other treatments. However when taking into account that the ryegrass had the additional costs of two extra fertiliser applications and higher seed cost and gross margins for the ryegrass and control where the same. Available for the project was a limited number of stock and as a result the ryegrass pasture was not grazed to its full potential. The group unanimously agreed that the number of DSE/ha grazing the ryegrass could have dramatically increased which in turn would have an impact on the gross margin results. The effect this would have had on the sustainability measures and long-term viability of the system is unknown however is thought not to be extreme.

The two treatments where also compared against the normal practise for the property. It is worth noting that the gross margins for the two treatments were $45/ha higher than that of the normal practise for the property. This highlighted to the group the potential to increase production purely through better pasture management.

Ultimately the project showed Italian ryegrass could be used in farming systems on the YP, however as alternative pasture species such as Italian ryegrass are costly to grow, unless they can be effectively grazed to take advantage of the extra growth there is no added benefit over current pasture species. Increasing grazing management skills to fully utilise existing pasture would be most beneficial in the short term with the view to introduce alternative species with superior growth into the system further down the track once pasture management could maximise livestock production.

Benefits to come out of the project include increased knowledge on grazing management and the realisation that extra pasture growth is of little benefit if it is not utilised and converted into increased livestock production.