Critical for profitability and future success in farms are the basics and adapting management protocols to genetic lines
Hatcheries and nurseries deliver good post larvae and juveniles from various genetic lines of broodstock. Entering this equation are manufacturers of early-stage feeds. How can all three come together to address the concerns of hatcheries and farmers? Over the last 10 years, breeding companies have marketed a range of genetic lines for the vannamei shrimp to meet the needs of an industry where there is no standardisation of culture systems but beset with changing environments and disease challenges. Are quality post larvae products of merely good genetics, hatchery management or their combination.
These were the issues discussed in a panel led by Rizky Darmawan, CEO, PT Delta Marine Indonesia, at TARS 2023 on Shrimp Aquaculture, held on August 15-16.
Genetics and environment – What next?
Dan Fegan, Chief Impact Officer at SyAqua Group compared shrimp with poultry production. Nutrition is well understood in the latter, while in shrimp, it is less well understood. For example, body temperature in chickens is consistent so there is less variation in digestion than in cold- blooded animals such as shrimp. The variety of conditions in shrimp culture (intensity, salinity, and temperature) is also much more variable and less controlled than in commercial poultry production.
Genetics is responsible for between 10 and 40% of the variation in performance. “Overall, genetic influence on performance is generally less than 20% with water quality, nutrition, stress, pathogens, and management, which is one component of the environment, having a strong influence on genetics” said Fegan.
Which genetics?
At SyAqua, the genetic selection process involves the annual evaluation of 400 families, looking at growth and followed by disease challenges such as acute hepatopancreatic necrosis disease (AHPND) and followed by DNA sampling to create the database for breeding values. This information is then used to select the best families to produce the next generation for commercial production. “Genetics is not a silver bullet. It will not make a bad farm good or a bad manager successful.”
Genetic lines can be selected for growth (“speed” lines), resistance (“resistant lines” or a combination of both (“balance” lines). Speed lines show fast growth under the right conditions but tend to be less resistant to environmental or disease challenges. Resistant lines may be more tolerant or resistant to disease or environmental challenges but show low growth. Balance lines provide a combination of good growth and resistance.
When selecting genetic lines, it also important to consider the health status. There are four descriptions used in the market: specific pathogen-free (SPF), specific pathogen-resistant (SPR), specific pathogen-tolerant (SPT) and “all pathogen-exposed” (APE). SPF shrimp are only free of specific pathogens and a list of these should be available if requested. Fegan clarified that SPR is only resistant against the specific pathogen(s) for which resistance is selected. SPT means shrimp can be infected but can withstand a higher pathogen load without any health issues. APE is not a real definition of health as it is highly unlikely that the shrimp have been exposed to all pathogens and since exposure does not guarantee tolerance or resistance, it is meaningless from a health standpoint.
Currently, the threats to genetics are diseases, rising costs, low prices, and climate change. “With higher competition and low prices, it is important to understand and manage costs when farmers have no control over the selling price ” said Fegan.
Environmental triggers such as water quality, overcrowding, biosecurity and health status can affect gene expression in positive and negative ways. Additionally, poor post larvae production practices can negate any genetic improvements. Therefore, the balance line approach aims to achieve the best results from the widest range of environments and culture conditions.
Fegan reminded that the days of fast innovation, low costs and high prices have ended. Future areas for improvement are related to the production environment, management, and resource use. Genetic improvement will continue to support improved production efficiency, but it is not enough on its own. “The industry requires data to make decisions
to improve production efficiency and maximise profits, but unfortunately few producers collect and use data routinely. Nowadays, we are in the new era of “big data” where information can be collected from a large number of farms and a wide range of conditions. Automation of data collection and analysis also holds promise for better understanding and management of resources for greater profitability.”
Crafting the foundation for farming efficiency in the first 30 days
Dr Olivier Decamp, R&D and Business Development Health Director at INVE Aquaculture, part of the Benchmark group, said that shrimp production costs vary with farming models and local conditions and currently range between USD2.2 and USD5/kg. For all the main shrimp-producing areas, the production cost is equal to or higher than farmgate prices. An important metric is the failure rate, high in Asia, such as 50% in Vietnam, compared to less than 5-10% in Ecuadorian farms. This impacts the profitability of a farm.
At only 8-10%, post larvae represent a small component of production cost but a critical investment for a farm’s profitability. A study of 4,000 crops by Grobest showed that the performance of farms operating under similar stocking densities was impacted by the hatchery supplying the post larvae (Figure 1, Decamp & Azpeitia, 2023). Hatcheries can control inputs from genetics, nutrition, and management systems. Their rearing protocols can be adjusted depending on genetics and nutrition.
Hatchery protocols
The expression of the potential of selected animals requires the correct rearing protocols and inputs. However, Decamp said the strict nursing measures either in the nucleus or broodstock multiplication centre can be compromised when moving broodstock to the hatchery. Without biosecurity procedures and the use of correct feed, the health and disease-free status of post larvae are impacted. Algae, live food, and water exchange can be a point of entry for potential pathogens.
“In the last 20 years, we have been looking at the microorganisms in the hatchery. These are the k-strategists, i.e., slow-growing, and dominant bacteria in a stable system, and r-strategists, harmful and fast- growing bacteria, such as Vibrios, that are dominant under unstable conditions. Regarding factors impacting the composition of the microbial communities, it is now known that 30-50% is associated firstly with algae, artemia and water inputs. There are new tools to reduce these disruptions. Emphasis should be put on making the system more stable.”
The message is to look at the inputs of products and get the best balance between feed and live food. In a fragmented industry such as shrimp farming in Asia, a hatchery needs to deliver post larvae which perform well in the farm and yet be profitable. Best Balance is an approach to shrimp hatchery culture in where the use of high-quality products is adjusted to the local culture conditions. Applying this approach in Thailand resulted in a higher number of harvested post larvae, which, in turn, has a cost-reducing effect on all the other cost contributors (evaluated as the cost per 1,000 post larvae produced). Benefits include a higher EBIT of hatchery operations and a further strengthening of the hatchery’s reputation through the supply of high-quality post larvae.
Decamp discussed the economics of using artemia in the hatchery. A Boston Consulting Group report gave data that artemia accounts for 5-30% of the total cost in the hatchery. There is a direct link between the total artemia used and larval biomass at 3.15kg per million artemia. A reduction in the use of artemia leads to a reduction in the larvae’s biomass, which indicates that artemia is still a critical live food. There are commercial hatcheries that
have dramatically reduced the inclusion rate of artemia in their feeding protocol. But the issue is to produce quality post larvae in a cost-efficient way,” said Decamp, while highlighting some back-to-basics approaches. The simple actions to be carried out in the hatchery when using artemia include disinfections, preparations and maintaining conditions.
Artemia feeding is a major source of pathogens in the system. Nutrients released during artemia hatching support the growth of Vibrio that are found in the hatchery environment. The idea is to reduce risk by preventing a bacterial bloom during the hatching and separating the cysts from the hatched artemia, as these cysts act as a substrate for Vibrio’s growth. Another INVE study, using a standard line of genetics, showed the relationship between the age of post larvae and tolerance to Vibro parahaemolyticus loads. This work justifies that larger post larvae are more resistant to pathogens. A compromise must be found between the robustness of the older post larvae and their ease of transport to the pond.
The conclusion was that ‘no one hatchery rearing protocol fits all,’ and all procedures must be continuously optimised according to the latest conditions and new technological developments. The transfer of larger and stronger post larvae helps to cope with disease challenges. A well-managed nursery phase, including biosecurity measures and optimal nutrition, will support the grow out performance. A crop’s success depends upon actions taken in the first 30 days of the life of a shrimp.
Genetics is a tool and not the solution
Further discussions at the panel included the participation of industry leaders active in shrimp genetics and hatchery management and travelling extensively in Asia; Dr Craig Browdy is Director of Research and Development at Zeigler Bros Inc, USA, and Steve Arce, Director of Technical Services, Kona Bay Shrimp-Hendrix Genetics Aquaculture, USA.
It all starts with the hatchery providing high-quality post larvae and then the appropriate management to be successful. Arce said that genetics can only contribute approximately 30% to farm performance, and 70% is influenced by management and the environment. The feeding rate and management systems should fit to the genetics. Genetics-wise, it is difficult to select for specific targets. Arce would like to see some standardisation of systems used and where their application will help geneticists develop the most appropriate strains.
Browdy expects the use of data to revolutionise and promote a better understanding of farm performance. He emphasised the importance of taking care of early life stages and differed on the absolute need for artemia in the hatchery for quality larvae production. Artemia usage has been successfully reduced and the successful replacement of artemia has been demonstrated. It is important to understand that larvae need good nutrition, not a particular ingredient or live feed. The driver of profitability in the hatchery is survival, with the most successful hatcheries investing in the efficient use of effective feeding and production technologies. Vibrio outbreaks have been increasing in Asian hatcheries. It is essential to work to reduce Vibrio loads to get the highest survival possible.
Sentinel testing
Since India is very much dependent on imported broodstock, how important is sentinel testing, such as the performance of 5-6 genetics lines in varying environments, asked S Santana Krishnan, India. According to Fegan, genetics companies already assess the suitability of their genetics under local conditions before suggesting the preferred genetics for farms in a particular country. Arce believes that sentinel testing, although easier said than done, can be useful when structured properly under standard conditions. But they need to generate large enough data sets to be useful. Arce cautioned that proper methodology and standardisation are critical.
Challenges with pathogens
Decamp said that breeding companies have been making massive progress with new disease challenges. “We look at new solutions for the farmer. Genetics-wise, it is to make sure the farmer receives a homogenous genetic line to stock in ponds. However, I do see that transparency in a fragmented market such as in Asia is difficult. There are reports of post larvae supplied by specific hatcheries performing better despite Enterocytozoon hepatopenaei (EHP) challenges.”
The farmer can choose genetic lines being offered to match the seasonal conditions and the seeding pattern, but Arce emphasised the need for management guidelines focused on biosecurity and nutrition. There will always be pathogens in the system, but with no apparent disease. Unfortunately, sometimes, genetics becomes a method to get away from analysing the effectiveness of management protocols.
Clearly, genetics can only offer the potential to reach a target when coupled with the proper management systems. Browdy said that different lines are suitable for different systems such as fast growth lines worked well in achieving growth rates that often exceed 4g per week in recirculation aquaculture systems (RAS) in the US, which are free of pathogens. Such lines may not work as well in other culture systems.
It was emphasised that pathogens change very often. “SPT and SPR lines selected for tolerance and/or resistance to, for example, white spot virus, will not work in the presence of background pathogens in the pond such as those causing AHPND. Fegan added that it is difficult for genetics companies to work with every pathogen to develop lines. “Neither can we be anticipating all new pathogens as we know that new diseases will always come along.” Arce added that selecting for stronger immune response (rigour/resilience) may be a path forward.
Dr Manoj Sharma, India, gave the example of genetics, environment and carrying capacity. The same genetic lines have performed well in new areas, such as Punjab, even with better feed conversion ratio (FCR) and high survival rates at 95%. However, in older areas such as Gujarat, performance was poor. Fegan agreed that this shows that genetics is a tool and not a one-size-fits-all situation.
Ultimately, we need to find the best genetics to match the situation; genetics is a tool with potential that can only be exploited with good management. It is important that farmers understand the role of genetics in maximising and realising their own performance potential.
Ablated versus non-ablated broodstock
Browdy said, “Over the past 20 years, as we select each generation, we have been directly or indirectly selecting for fecundity, as the best spawners typically pass their genes on to the next generation. Today, we have females with higher pro
ductivity in terms of mating rates and spawn size. Increased fecundity has enabled the use of non-ablated broodstock. Moreover, SPF broodstock are expensive, driving hatcheries to develop strategies to maximise output in terms of fecundity in the short term and productivity in the long term. Fegan offered information on a University of Stirling disease challenge with WSSV, which showed that post challenge survival was higher in post larvae from non- ablated females, showing that ablation could also impact post larvae quality.
While there is a move for market acceptance for no ablation in hatcheries due to animal welfare concerns, the panel noted if large markets are not too concerned with ablation, the future uptake of no ablation will be slower.
What would they ask hatcheries?
Moderator Rizky Darmawan challenged the panel to wear the hat of a farmer and ask questions on post larvae quality.
Browdy: Hatcheries tend to apply feeding protocols that use a cocktail of higher and lesser quality feeds to reduce input costs. However, these strategies are detrimental to the output. Whereas a small rise in survival raises output and profitability. I would ask the hatchery manager, “How good are your post larvae? How much have you invested in them and how can higher survivals and more robust post larvae improve your profitability while helping the farmer?”
Decamp: I would query the number of post larvae produced, the quality control using standard methods and how digital tools are used to assess variability in batch quality. I would want to visit the hatchery and get data on my batch of post larvae in production.
Arce: I would ask what the hatchery’s failure rate and their farmers’ success rate is. If the reply is hit and miss, as a farmer, I would go with the hatchery with consistent batches and a solid client base, a good level of adaptability of management protocols regarding seasons and genetic lines. Flexibility and being open-minded to evolve are crucial.
Fegan: I would also ask the hatchery to provide evidence of the source of their genetics as there have been several cases of “fake” genetics in the market.
The article was published in issue January/February 2024 AQUA Culture Asia Pacific
