It is estimated that 1000 tonnes of formulated feeds are used to achieve the current level of production. Feed is considered as the major variable cost (up to 30%) associated with abalone production (Mr Justin Fromm, personal communication), so minor improvements in feeds or feed efficiency may result in large improvements in productivity. There are currently four feed manufacturers supplying the abalone grow-out sector and each feed company typically offers one formulation of feed for the entire ~2.5 year production cycle of greenlip or hybrid abalone. It is common practice in other sectors of the livestock industry to use a range of different diet formulations throughout the production cycle to satisfy the requirements of animals of different life stages. It is also well established that in the wild abalone have at least two distinct feeding strategies as they develop with young cryptic abalone grazing on epiphytic organisms whilst older animals feed on macroalgae. Improvements in commercial feeds formulated for abalone, specifically for different life stages and/or water temperatures (seasonal/inter-annual/climate change), are likely to deliver improvement in weight gain per unit cost across an entire grow out period.
As a result of a recent R & D planning meeting held by AAGA, other industry participants, AS CRC and research providers, the AAGA perceive that the current commercial abalone feeds do not contain the required nutrient combinations to meet the genetic potential for growth. Australian abalone feed producers have based dietary formulations on information from previous FRDC funded projects. The information from the FRDC projects, including a range of ingredient nutrient availability and nutrient requirement data, resulted in the standard of Australian abalone feeds surpassing Japanese abalone feeds (considered as the benchmark at the time). AAGA have identified research in this area to be their highest priority within the AS CRC.
The key research findings described in this project addressed the two highest research priorities identified by the Australian Abalone Grower' Association (AAGA) in 2009, prior to the commencement of this project.:
- Improve our understanding of the effects of seasonal water temperatures on the growth of abalone; and
- Improve our understanding of the effects of dietary protein on the growth of abalone
Members of the AAGA were interested in determining if multi-diet feeding strategies designed specifically to provide the optimum dietary protein level to the abalone in response to animal age and seasonal fluctuations in water temperature improve production. Additionally, the planned overall outcome from tis project was to develop commercial diet formulation and feeding strategies that deliver a >10% improvement in productivity across an entire grow-out period for greenlip (Haliotis laevigata) and hybrid abalone (H. laevigata x H. rubra). To achieve this outcome, a series of laboratory-based experiments were designed to improve our understanding of the optimum dietary protein levels for greenlip abalone and also characterise the growth and feed utilisation of greelip abalone of different age classes at a range of seasonal temperatures (14-22oC) representative of those experienced by abalone in land-based facilities in southern Australia (Chapters 2 and 3). This information was then used to design and run three commercial on-farms trials at the Great Southern Waters, Costal Seafarms and Kangaroo Island Abalone (Chapters 4 and 5). The on-farm trials comprised a series of three long-term (>18 months) studies, using commercial culture practices, to evaluate the growth, feed utilisation and survival of greenlip and hybrid abalone using two different feeding strategies:
- Single-diet feeding strategy: the current production method of feeding one standard protein for the entire trial
- Multi-diet feeding strategy: fed a sequential combination of "high protein"/"low protein" grow-out diets for the entire trial.