September, 2020
Shrimp Insights: SPF L. vannamei BROODSTOCK Shrimp Insights Report Series
Click on the link to download the entire report: https://shrimpinsights.com/report-series/vannamei-broodstock
The shrimp broodstock industry is advancing quickly, bringing new potential for growth, disease resistance and other genetic improvements. Advances in our knowledge of the nutritional and physiological requirements of the maturation process have led to improvements in maturation feeding programs. Prepared diets designed specifically for the different physiological needs of each stage of broodstock development are now available. When accompanied with tailored feeding programs, producers can realize significant gains in the quality and consistency of nauplii while enhancing biosecurity.
Despite these advances, the industry remains heavily dependent on fresh and live feeds as mainstays of broodstock feeding programs. This dependence has cost the industry billions of dollars due to the well-documented role of these feeds in the transmission of diseases such as WSSV, AHPND, and EHP. Now more than ever, critical gaps in the nutrition and biosecurity of maturation programs must be prioritized, evolving broodstock feed programs to maximize the potential gains from genetic advancements. Achieving 100% replacement of fresh and live feeds requires a sus-tained industry effort, to ensure that broodstock programs everywhere can meet the growing demands for high quality nauplii.
Based on diligent research and over two and a half decades of experience producing shrimp broodstock diets, we draw on Zeigler’s global expertise and its 85-year history of feed manufacturing to share perspectives on this subject.
Broodstock Nutrition Programs
The physiological processes associated with maturation are complex and dynamic. The nutritional requirements of the shrimp change as the shrimp progresses through the maturation process. A well designed broodstock nutrition program ensures precise levels of nutrients and energy are delivered to the animals throughout the maturation process to consistently produce healthy, high quality nauplii. Customized broodstock diets should be introduced to animals from an early age to optimize the animal’s potential and to put the producer in control. As the shrimp approach sexual maturity, a more nutrient dense diet should be phased in, enhancing gonadal development and conditioning. As the shrimp enter active reproduction, special maturation diets must be fed to support repetitive spawning of healthy eggs and sperm.
Properly formulated diets and good feeding protocols ensure that animals have a consistent delivery of critical nutrients such as phospholipids, HUFAs, carotenoids, amino acids and vitamins at the required levels for their developmental stage. Advanced broodstock diets contain additives to assure robust immune balance and gut health. Manufactured diets offer the safest and most reliable option for delivery of the proper balance of nutrients and health additives.
Live and Fresh Feeds
A wide variety of fresh and live feed are commonly used in maturation feeding programs, including squid, polychaetes, mussels, oysters, clams, Artemia biomass and krill. The nutritional profile and overall quality of live and fresh feeds varies based on the sourcing location, seasonality, and changes in environmental conditions. Moreover, nearly every hatchery uses different combinations and percentages of fresh and live feeds, resulting in wide nutritional variations between hatcheries.
In Asia, live polychaetes are widely used because they support very high nauplii production levels. This reliance on wild-harvested live polychaetes for enhancing fecundity is a major contributor to introduction and spread of diseases such as WSSV, AHPND, and EHP. Although freezing the worms can reduce infectivity of some pathogens, nauplii productivity suffers and many producers are unwilling to sacrifice higher nauplii production for the sake of improved biosecurity.
Farm-raised frozen polychaetes are a biosecure alternative to live polychaetes. Likewise, frozen squid sourced from areas geographically isolated from shrimp production regions also reduce the risk of introduction of pathogens into the hatchery. However, frozen fresh feeds consist of 80-90% water, so air freight adds a significant investment per unit of dry weight nutrition.
Inventory management of fresh and live feeds present their own challenges. High quality frozen fresh feeds are typically imported using a cold storage chain adding costs and risk to maintain shelf life. Alternatively, manufactured diets offer a longer shelf life, easing inventory management and ensuring greater consistency for the maturation program.
Biosecurity
To minimize the risk of introducing disease from wild and farm reared spawners, the use of specific pathogen free (SPF) broodstock is rapidly becoming the industry standard. Governments also strictly regulate the import process. This comes at a significant cost to producers. Ironically, once reaching the hatchery, the disease-free status that managers paid so much to obtain is frequently compromised by the feeding of fresh and live feeds to maximize nauplii production. While this may increase short term profits for the hatchery owner, the economic losses to farm operators and to the industry totals billions of dollars every year.
A Necessary Transition
The arguments to increase the use of manufactured diets are overwhelming but resistance to change is significant. As Al-bert Tacon, a recognized leader in the subject of aquaculture nutrition has stated, “In view of the potential disease risks from the use of pathogen-contaminated, live and fresh natural feed items, it would be prudent for the shrimp industry to sacrifice lower hatchery performance and contamina-tion of their valuable specific pathogen-free broodstock by moving over completely to the use of commercially manu-factured biosecure larval and maturation feeds.” Journal of the World Aquaculture Society Volume 48: 381-392.
A well-designed maturation feeding program utilizes biosecure feeds in quantities adjusted for broodstock consumption levels. To be effective, prepared feeds must be consumed in quantities necessary to provide the desired nutritional impact. Because different feeds vary with respect to moisture content and available nutrients are largely associated with the dry matter, feed rates should be based on the percentage of dry matter in the feeds. Complete replacement of all fresh and frozen feeds other than squid has been successfully achieved using high quality formulated feeds fed to replace fresh feeds on an equivalent dry weight basis.
When manufactured diets are introduced, a highly conservative approach can impair progress. Traditionally, manufactured diets are fed at 1 to 1.5 percent of tank biomass. However, feeding of high-quality manufactured maturation diets at such low levels mutes their nutritional impact. For best results, an attractive advanced diet should be fed at >2.5% dry weight to tank biomass. The manufactured feed should be greater than 50% of the total dry weight fed. Utilization of older animals that have been habituated to fresh feeds for testing new diets can also be problematic. Younger animals conditioned on prepared feeds from stocking provide the best results.
In summary, technologies for prepared maturation diets are improving. Better ingredients optimized nutritional composition, improved attractability, effective additives and innovative manufacturing technologies are contributing synergistically to improving performance. When properly incorporated in a complete maturation program these feeds provide a basis for reducing use of live and fresh feeds, enabling more biosecure and robust nauplii production.
ZEIGLER’S COMPLETE MATURATION PROGRAM
Zeigler’s unique Broodstock 1-2-3 Maturation Program encompasses a range of diets specially adapted for every phase of a broodstock program.
Once animals have been isolated for future breeding, conditioning can begin to prepare for the best long-term results. A tailored feed like Zeigler’s Shrimp Broodstock diet can be introduced to animals as small as 7g and is suitable for use in open systems.
Once animals begin the physiologically demanding phase of gonadal development the need for more nutrient dense diets becomes more acute. Zeigler’s Shrimp Maturation Conditioning Diet is optimized with micronutrients to optimize gonad reserves, accelerate mating rates and increase spawn sizes. This diet is specially designed for use in tank-based systems.
Upon reaching the active spawning phase, consistently supplying optimized nutrition reaches new levels of importance as metabolic demands on broodstock peak. Zeigler offers two unique diets for this stage, EZ Mate and Redi-Mate, which both contain extremely high levels of carotenoids and vitamins to promote and sustain good spawning rates and increase the number and quality of nauplii per spawn. Both diets have been carefully developed to maximize attractability and ensure uptake of vital nutrition to sustain optimized production.
EZ Mate is a highly adaptable powdered diet which is made into a dough by the customer. This allows customization of the feed by adding other ingredients and shaping the diet into a preferred format. Redi-Mate, Zeigler’s newest broodstock diet, encompasses the latest nutritional science and manufacturing technologies resulting in a highly attractive, semi-moist pellet, which is ready to feed.
Shrimp Insights: SPF L. vannamei BROODSTOCK Shrimp Insights Report Series
Click on the link to download the entire report: https://shrimpinsights.com/report-series/vannamei-broodstock