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Who is the report targeted at?
The report provides information to a range of stakeholders. The progress in characterising disease resistance is of importance to industry breeding programs and to international research groups working on rabbit genetics. The applied results from the evaluation of equipment for rabbits have direct relevance to commercial farmers. The report on genetic progress with Crusader stock is valuable information for breeders looking for superior rabbits to improve their profitability. The scientific outcomes will guide future R&D investment and the recommendations on new technologies will feed into policy development for the industry in areas such as AQIS importation protocols for rabbits.

Background
The rabbit industry is at the stage of consolidating with the size of farms beginning to increase (>400 breeding does) as individual business become solely focused on rabbit production, including processing, product development and wholesaling. On-farm processing capacity has been a key component of successful enterprises as this removes the expense of transport and provides the opportunity to add to profit margins by processing and wholesaling meat.

Approximately 300 tonne rabbit meat was produced in 2005/06 with a farm gate value of $2.2 – 2.4m.

With an average production of 25-30 growers per doe per year, this puts the breeding population at approximately 6,800-8,200 does. The industry appears to be doubling every 3-4 years. Current estimate for gross margin per doe is approximately $174/annum, which is net of variable costs of production excluding labour.

The rabbit industry has tapped into a niche market for high value meat with the majority of rabbit being sold though restaurants and specialty butchers shops for between $15-$20/kg retail. It has a relatively low fat level and is considered to be a healthy white meat. An important challenge for the industry is to maintain the “clean, green and healthy” image of rabbit meat. The application in Australia of some disease control strategies employed in Europe, such as prophylactic feeding of antibiotics, needs to be treated with caution to protect the market position of rabbit meat. The continued emphasis on genetic improvement of disease resistance in the Crusader breeding program is primarily to target this issue.

Aims and objectives
The project was undertaken from June 2004 to July 2007 and its goals were to improve the genetic merit of Crusader rabbits, commercialise the breeding program and provide information on management for increased rabbit production. The specific outcomes and deliverables set for the project are listed below:

• Leading edge genetic improvement program for meat rabbits incorporating innovative and new traits that impact on farmer profitability, such as disease resistance, doe health and longevity.
• Establishment of the 120 doe Crusader herd at Snowy Mountains Gourmet Rabbit Company (SMGRC) facility at Bredbo, NSW, so that it is running independently.
• Improved Crusader breeding stock through the conduct of a selection program based on estimation of estimated breeding values (EBVs), index ranking of animals and appropriate mating allocation.
• Through the regular sale of breeding stock, Crusader rabbits being used in industry and contributing to improvements in farmers’ profits
• Recommendations for industry on improved management options for rabbit farmers, in the first instance recommendations on kit boxes for improved kitten survival
• The establishment of a national meat rabbit genetic evaluation program, with Crusader acting as a hub to provide genetic linkage between breeding herds.

Methods used and results/key findings
Genetic progress for Crusader selection program
Overall progress in the breeding program, as indicated by the average index value of rabbits, has been substantial with a combination of genetic and management improvements lifting gross margins from an estimated $174 to $242 per doe per annum. The average index value of animals has improved to +$55 per doe per annum, indicating that a significant proportion of the improvement has been from genetic sources.

There has been good progress in the number of kittens weaned given the relativity low heritability for this trait. Given mean starting values of 4 kittens weaned per litter, genetic improvement has been approximately 12.5% for kittens weaned over the 6 years of selection, or approximately 0.4 of kitten per year. Average daily liveweight gain for growers (ADG) has shown a consistent upward trend as expected for a trait that is moderately to highly heritable. Given mean starting value 34 g/head/day for growth rate, genetic improvement has been approximately 29% for growth rate since the breeding program commenced in July 2001. Resistance to bacterial infection in growers is the most recent trait to be introduced to the breeding objective, being included in the selection index in mid-2003. Given a mean starting value for average infection score of 0.50, genetic improvement has been approximately 9% for disease resistance since 2001.

Genetic improvement in litter size and growth rate has been consistent since selection commenced in 2001 and was not interrupted when the rabbits were relocated to SMGRC in 2004. However, progress in improving disease resistance was only evident for the first year after the rabbits were transferred to Bredbo (mid-2004 to mid-2005). This probably reflects a lack of consistency in scoring the rabbits for signs of disease, a subjective assessment that is less well defined than liveweight or number of kittens.

Transfer to industry and independent operation of Crusader
The transfer of the Crusader breeding program to industry has been successful and may serve as a useful model for other new animal industries. The critical success factors were:

• identification of a commercial operator that had the capacity to take on the task
• the development of database systems and interface with BLUP software, in a MS Access environment that allowed ease of use by relatively unskilled operators
• the detailed documentation of all activities in Standard Operating Procedures
• flexibility to vary the intensity of data collection to fit a more commercial schedule of production
• a period of support and transition
• access to on-going support as required for occasional auditing and adjustment of procedures The transfer has also highlighted areas of difficulty that needed to be addressed to ensure efficient operation and data integrity:
• presence of physical card records in the shed to allow shed operators without access to the database the ability to monitor doe performance and flag when anomalies were occurring. This was particularly evident when procedures for generating accurate mating lists failed and does were not being regularly mated.
• timely data collection and entry for a weekly management system that requires data to be up to date to efficiently generate the next weeks’s worksheets training of new staff in data collection so that consistency of approach was ensured. This was particularly evident with subjectively assessed traits such maternal behaviour, body condition and disease incidence scoring.
• timely adjustment of data recording levels where time constraints were impinging on quality and frequency of data collection.

The total time taken to train staff at SMGRC so that the program could be run independently was approximately 12 months. Proficiency was achieved in data collection and entry routines within 2 months, estimation of EBVs and selection of breeding stock within 4 months and buck and doe allocations within 12 months. The program now operates with periodic auditing of mating allocations and genetic trends.

Overall, Crusader has demonstrated that a sophisticated and modern breeding program, estimating breeding values every 3 weeks for index selection of breeding stock every 6 weeks, can be run relatively independently in industry.

Scientific advances for Crusader
Scientific advances were made in selection for disease traits in grower rabbits, estimating genetic parameters to allow selection for functional traits related to healthy and productive animals, and in identifying the relative balance to place on these traits compared to production traits such as growth rate and number of rabbits weaned per litter.

Resistance to bacterial infection
The studies of resistance to bacterial infection in grower rabbits established and refined the parameters required to effectively incorporate this trait into the selection program. Incidence of visual signs of bacterial infection and mortality, from causes related to bacterial infection, was recorded on a weekly basis in growing meat rabbits from 5 to 10 weeks of age. Heritability of weekly incidence of disease was highest in weeks 9 and 10 (0.05±0.02 and 0.06±0.02, respectively with linear model, and 0.10±0.06 and 0.12±0.05, respectively with a threshold model). Common litter effects accounted for 5-20% of the variance of disease incidence, while maternal genetic variance was small (0-3%).

Individuals from small litters at weaning had higher disease incidence, and disease incidence reduced as litter parity of the doe increased (P<0.05), when the disease trait was measured at week 9 and 10, but not for earlier weeks.

Genetic correlations between disease incidence and mortality were imprecise and not different from zero. Phenotypic correlations were low to moderate, and positive. Although the mechanism at this stage is unknown, these findings suggest that there are common/shared immunological responses to bacterial challenge that are under genetic control. This study demonstrates that observed signs of bacterial infection in rabbits can be used as an indicator trait for resistance to bacterial infection, and the heritability of the trait is high enough to warrant its inclusion it the breeding program. From one week to the next, rabbits exhibiting disease symptoms were more likely (10 to 50 times depending on week of measurement) to die than those that were healthy. The relative economic value of resistance to bacterial infection was based on the relationship between disease incidence and survival, as well as the direct costs of effective disease control and treatment.

Preliminary estimates of the heritability of resistance to bacterial infection in breeding does and the correlation between the train in the grower rabbit and breeding doe were inconclusive due to too few records for breeding does at this point in time. The heritability estimate for this trait was 0.014±0.10, indicating the data (n=459) is still too sparse for reliable parameter estimation. Once additional records are available, the data require a more rigorous analysis with a repeated measures model or survival analysis approach that accounts for censored records.

For female rabbits, the phenotypic correlation was 0.16±0.05, between signs of infection at growing age (8-9 weeks) and subsequent signs of infection as a breeding doe. Presented as class means, does who were not sick at 8 or 9 weeks of age had an average incidence of sickness of 40% in the 3rd week post-partum. On average does who were sick once at either 8 or 9 weeks of age had a later incidence of sickness of 59%, and for does who were sick at both 8 and 9 weeks of age the incidence of sickness in the 3rd week post-partum was 67%.

These results are encouraging and highlight the need for more data to be collected so that the overall merit of selection for disease can be assessed in both grower and breeding rabbits.

Adding functional traits to the breeding objective
The relative importance of functional traits in a breeding objective can be determined by assessing the financial contribution of one phenotypic standard deviation change in the trait while keeping all other traits constant. For functional traits such as doe longevity (length of productive life), there can be difficulties separating the trait from other traits such as disease incidence or reproductive performance and the risk of double counting needs to be understood.

The relative economic value (REV) was estimated for selection traits for Australian meat rabbits using a gross margin model based on average industry parameters (Eady 2004b) where average returns were $174 per doe per annum. Traits that determine the rate of kitten production have the highest REV, in the order $102-$116 per doe per annum in absolute value, while growth traits including feed conversion efficiency are next in relative importance. Functional traits contribute to profit but are less important, with resistance to bacterial infection in grower rabbits of similar absolute REV to liveweight gain, and doe longevity the lowest at $7.31 per doe per annum.

The financial returns from higher kitten turn-off, reduced feeding costs to meet a target weight and lower mortality of growers are clear. Improving doe longevity reduces the overhead cost of the doe population. Fewer does are needed as replacements, meaning that more are sold for meat income, and maintenance costs from meat turn-off age to first mating are reduced. Given the fecundity of rabbits these are not major costs in a self-replacing breeding unit. In other systems, where replacement does from specialist maternal lines are purchased, the REV for longevity may be higher.

The selection index for the Crusader breeding program contains the traits number weaned/litter, average daily gain and resistance to bacterial infection in grower rabbits. As there are limited resources for introducing new traits, it is likely to be more profitable to focus on improving feed conversion efficiency rather than longevity, in the first instance. The relative contribution to the profit function can be approximated by the product of the heritability and REV, indicating an 8-fold greater contribution from improving feed conversion efficiency compared to doe longevity.

Although there is a clear role for functional traits in a meat rabbit breeding objective, further work is required to complete the picture. Studies are required to determine the genetic relationship between functional traits such as disease resistance, longevity and production traits. With regard to selection for improved longevity, the detrimental impact on generation interval needs to be considered. There also needs to be some method of accounting for the risk that current control measures for disease, such as the prophylactic use of antibiotics in grower feed, may be banned or restricted.

Equipment for meat rabbits
Two ancillary experiments yielded practical recommendations on design of cage equipment (mats and nest boxes) that can potentially improve the welfare and productivity of breeding does. The results show that, in the environment experienced by the experimental rabbits, sore hocks (pododermatitis) can be reduced in breeding does from an incidence of 4% down to less than 1%, by the provision of suitable pressure mats. The difference between the highest and lowest performing nest boxes, in terms of number of kittens weaned, translates into a difference in enterprise gross margins (Eady 2004) of $58.60 per doe per annum, or an increase of 40% in profit from the use of the best performing nest box compared to the worst. Farmers can use the results as a guide to choosing or constructing nest box equipment, and should be encouraged to objectively compare different designs under their own environmental conditions. Information on cage equipment, productivity levels and gross margins for the industry has been made available for farmers to bench-mark their performance.

Industry engagement and transfer of technology
Crusader has contributed to industry events and forums over the duration of the project including field days and meetings held by Farmed Rabbit of Australia (FRIA), a joint Crusader/SMGRC field day and trade display, and various regional activities. Links for industry input into the project have been maintained through the Crusader Advisory Group. A steady stream of enquiries for information has continued through the project from prospective farmers (Australian and overseas) and industry advisors. The Crusader website (www.csiro.au/crusader) was upgraded and moved to the new CSIRO web architecture in March 2006 and information on Crusader was added to the SMGRC website (www.smgrc.com.au).

As an investigation into the provision of a commercial service for genetic evaluation proved too expensive for the industry, genetic links have been built with Growtec (the other major breeding program for meat rabbits in Australia) to allow an across-program evaluation. Constraints have been the logistics of shipping animals but more importantly concern about quarantine, with rabbit operations in Victoria reporting significant occurrence of disease (scouring) with an, as yet, undefined cause. Once progeny have been produced from the more recently exchanged bucks, a joint analysis will be undertaken between the two breeding groups. In the mean time, Crusader bucks have contributed to the Growtec program and vice versa, assisting in the dissemination of superior genes to the industry overall.

The concept of licensing multiplier breeders was investigated but there was not the commercial imperative or business case for investment by SMGRC during the life of the project. This may be an attractive option for breeders in the future as they would yield the benefit (with a lag period) of genetic improvement and increased potential for sale of breeding stock, without the large cost and management expertise to run a full program on-farm. There remains the need to have improved rabbits more geographically dispersed so that breeding stock can be readily accessed.

Sales of Crusader stock to industry have continued over the three years of the project. There is a need for an on-going promotional program to maintain higher levels of breeding stock sales. The response to the FRIA field day in South Australia demonstrated that demand for rabbits is present if logistical constraints can be managed and information on the merit of the rabbits widely distributed. It will be important for the Crusader breeding program to develop the capacity for semen collection, storage and shipment as AI is adopted more widely in industry.

Implications for relevant stakeholders
New traits and directions for genetic improvement
Crusader breeding program has progressed well and it is now prudent to explore new traits that can further improve profit. Traits that have been considered include doe longevity, doe health and litter size, and feed conversion efficiency of grower rabbits. The selection index for the Crusader breeding program already contains the traits number weaned per litter, average daily liveweight gain and resistance to bacterial infection in grower rabbits. As there are limited resources for introducing new traits, it is likely to be more profitable to focus on improving feed conversion efficiency rather than doe longevity, in the first instance. The relative contribution to the profit function can be approximated by the product of the heritability and REV, indicating an 8-fold greater contribution from improving feed conversion efficiency compared to doe longevity.

However, improvement of litter size at weaning still offers the greatest potential for improved financial gain. Progress is steady and encouraging in the Crusader program but could be accelerated considerably by the introduction of European stock. The gap in performance between Crusader stock and rabbit strains in Europe is most evident for prolificacy, with an average of 7 kittens born alive per litter and 5 reared, compared to 9.9 and 8.4 kittens per litter, respectively, for commercial meat rabbits in France.

The difficulty in acquiring rabbits or semen from France is in meeting the quarantine requirements for entry into Australia. The recent establishment of a Specific Pathogen Free (SPF) population of xi one of the maternal grand-parent lines in France is an encouraging development, as this potential source of rabbits would meet the in-country quarantine required before the rabbits leave Europe, an expensive component of any importation. It may be worthwhile exploring again the possible importation of rabbits and/or semen with AQIS and industry stakeholders.

Introduction of artificial insemination (AI)
A number of industry members have invested in training for their staff and have brought people with expertise from Europe to assist with setting up procedures and laboratories to allow them to undertake AI on-farm. Technical assistance is also available from Mark White, Allied Biotechnology, within Australia.

Along with the introduction of AI, will come the need to upgrade cage equipment, such as nest boxes, as an important part of bio-stimulation to achieve good conception rates is to restrict doe access to kittens for the 10 day period between kindling and AI.

Although genetic gain is satisfactory for the Crusader breeding program, the introduction of AI would allow selection intensity to improve and accelerate rates of gain. It will also be important for the Crusader breeding program to develop the capacity for semen collection, storage and shipment, as AI is adopted more widely in industry.

Appropriate adoption of European technology
Rabbit producers have travelled to Europe to observe advanced husbandry systems being employed there. Some technologies, such as AI, offer significant benefits without posing a risk to the industry. However, other practices, while improving rabbit productivity and health, have the potential to be detrimental to the industry's reputation and image. One such practice is the prophylactic feeding of antibiotics to grower rabbits. Genetic resistance to bacterial infection was introduced to the Crusader breeding program with the purpose of assisting the industry to avoid the need to feed antibiotics. Progress needs to be tested to see if antibiotics can be omitted from grower rations for Crusader stock.

Meat quality
Initially the rabbit industry's prime concern was to produce the rabbit numbers required by the market. As the industry grows it needs to ensure eating quality is consistent. At some stage the industry should consider investment in research on critical factors for meat quality to help build continued growth in overall demand as well as ensuring a consistent and regular market.

Recommendations
The project sets the industry up with a genetically superior source of seed stock that will feed into current production systems, based on natural mating, and new systems where there is an increasing use of advanced technologies such as artificial insemination. Crusader provides an on-going resource that can be used to test and incorporate new selection traits for improved production. The highest priority will be feed efficiency and number of kittens weaned. It would be advantageous to investigate the feasibility of importation of highly prolificacy lines of rabbits from Europe for improving the latter trait.

Scientific advances were made in selection for disease traits in grower rabbits, estimating genetic parameters to allow selection for functional traits related to healthy and productive animals, and in identifying the relative balance to place on these traits compared to production traits such as growth rate and number of rabbits weaned per litter. It is recommended that this type of data collection continue to allow parameters for breeding does to be estimated with increased confidence.

The transfer of the Crusader breeding program to industry has been successful and may serve as a useful model for other new animal industries. Overall, Crusader has demonstrated that a sophisticated and modern breeding program, estimating breeding values every 3 weeks for index selection of breeding stock every 6 weeks, can be run relatively independently in industry.