【在线交流】对虾苗种繁育及养殖场管理@Dr. Matthew Briggs，6月18日下午16:00

马修

亲虾第一次产卵产出的虾苗质量是否比后面几批的质量要差一点？

yes, usually the very first batch of eggs is noit very fertile so does noit hatch very well. Most people discard and use the second batch
unless you use old males, which can provide better fertility

翻译：
是的，第一次产卵产出的虾苗质量会不太好，大部分人选择放弃第一次产出的卵。
当然，你如果使用老的公虾繁殖力会更好一些

马修

翻译：
是的，第一次产卵产出的虾苗质量会不太好，大部分人选择放弃第一次产出的卵。
当然，你如果使用老的公虾繁殖力会更好一些

马修

夜雨 发表于 2013-6-18 11:42
请问马修博士是怎么看待EMS的啊？

EMS = Early Mortality Syndrome
Early mortality syndrome can be caused by a number of different pathogenic, environmental and management issues. Some, but not all of this appears to be caused by a new and previously unknown syndrome called Acute Hepatopancreatic Necrosis Syndrome (AHPNS)
In Vietnam sampling has shown only 50% of EMS is caused by AHPNS (the rest is WSSV and other problems)
In Thailand – the figures are <30% caused by AHPNS
could you be specific so i can answer?

Cause unknown for 4 years, but this month, Dr. Lightner from Arizona, working with Flegal in Mahidol and FAO/ NACA/World Bank finally identified causative agent as a specific strain of Vibrio parahaemolyticus transmitted orally & colonizing intestine

马修

逆游的鱼 发表于 2013-6-18 16:13
我也来提一个问题吧：
在对马来西亚一个大型综合性养虾场的研究表明，早期死亡综合症（EMS）在池塘水体pH值 ...

in general, lower PH means less probelm with vibrio(vibrio is the cause of EMS), and also, high PH can cause probelm with Amonia which stress the shrimp. so keep in low PH is good idea.
我赞成。维持较低的PH值可减着少弧菌的烦扰（弧菌现在被认为是导致EMS的原因），同事，过高的PH还会带来氨氮对虾造成应激的问题。因而，降低PH值是个不错的措施。

马修

normally we use probiotics which are mostly comprised of a mixture of bacillus and lactobacillus species - these can help remove toxic ammonia and nitrite, outcompete vibrios and actually kill off bad vibrio species. They thus improve environmental conditions.
some people also brew their own non-pathogenic vibrio strains in the hatchery, but they do not help water quality, only outcompete pathogenic vibrios

翻译：
通常我们使用的益生菌，大多数是由芽孢杆菌和乳酸杆菌，他们可以帮助清除有毒的氨氮和亚硝酸盐，o控制弧菌，改善对虾生长环境。有些孵化场自己培养非致病性弧菌，这样做对水质改善没有帮助，只不过可以对抗致病性弧菌

马修

yes, organic acids can lower pH in fish/shrimp gut from pH 7 to pH 4-5 which can kill pathogenic gram negative bacteria like vibrios, buit does not kill gram positive probiotic bacteria
this is used alot in livestock (pig, chicken) but not much yet in shrimp. But it does work both in hatchery and pond farms

翻译：
是的，有机酸能将虾肠道内的PH从 7降至4-5，可以杀死致病性革兰氏阴性菌如弧菌，但不杀死革兰氏阳性菌。目前很多家畜（猪，鸡）上都在这样使用，虾上用的不多。但它的确在苗场养殖和养殖场都非常有效。

马修

in Chinese hatcheries the main problem is reliance on old ways of management. There does not seem to be much capacity for problem solving.
I think the biggest problem is not using live algae. Live algae must be grown with care so it is not contaminated and then is ideal feed for larvae, but also helps maintain water quality and even reduce vibrios. If it is done badly and poor quality then it is bad, so most Chinese hatcheries do not do it. If done properly it is very good.
the other main problem is a focus on quantity rather than quality. In order to get high quality PL you must focus on quality

翻译：
在中国，主要问题是对于旧的管理方式的过度依赖，似乎没有太多的从解决问题的角度去考虑。我认为最大的问题是不用活藻。而且活藻的培训必须要非常的严格，让它不受污染。活藻不仅是理想的饵料，而且有助于保持水质以及减少弧菌。但是活藻如果培育得不好，质量差，它会带来不好的影响，所以大多数中国孵化场不做。但如果做得好，这对育苗帮助是很好的。另一个主要问题是注重产量不注重质量。想要培训高品质的虾苗你必须关注这一点。

马修

Normally, we only use the broodstock for 4 months as after that they become used up and do not produce good quality nauplius any more. So once we ablate, we use continuously for 4 months, then get a new batch. We do not stop and start with the same batch

马修

If you have already got EMS you must stop feeding immediately for 5-7 days then start again slowly after that. You stop feeding to try to improve the environment and help the shrimp recover. also, controlling water quality (with probiotics) and trying to keep algae bloom stable and not allow rapid fluctuations in pH or high pH levels may help. However, sometimes none of this helps and you mjust harvest pond and start again

马修

You are right - the hatchery is controlled and "sterile" environment while the pond fluctuates widely
Normally the PL or even juveniles in the nursery do not suffer from EMS, but when we stock the ponds, immediately they do. Thus the stress of moving them and the stress factors in the ponds obviously affect them very quickly.
Many Asian farmers are used to killing everything in the pond to try to start clean, but if you do that (with chlorine or pesticide) then quickly bacteria will grow back - there is always bacteria - you cannot stop them. so you have to make sure the ones that grow back are non-pathogenic - i.e. add alot of probiotics or heterotrophic bacteria right away during pond preparation otherwise bad bacteria will grow quickly.
One farm in Thailand avoids EMS by not killinbg everything, but fertilizing to produce good bloom of diatoms and zooplankton (copepods) to promote a good environment at it seems to work to avoid EMS


翻译：你是对的。育苗场是相对“无菌”的环境而池塘的环境随时都在变化。因而当我们把苗发到塘中后，他们容易出现EMS，而在这之前不会发生。很明显，我们放苗以及塘中的环境会对他们造成很大的应激。亚洲的许多养殖户在遇到EMS后，就直接清塘，用氯或农药消毒，希望下一造干干净净地开始。但实际上，细菌很快地地又卷土重来了——细菌总是存在的，你不可能阻止。所以你要确保的是塘中存在的细菌是非致病性的，即增加很多益生菌抑制有害菌的生长。在泰国的一个农场，通过促进藻及浮游生物及有益菌地生长，从而维持一个比较好的水质环境。从而很好地预防EMS的问题。

马修

Shrimp and fish polyculture is very good, as the right species of fish has a very positive effect on the water quality (especially vibrio levels) in the water and sediment, helping the shrimp to fight disease. Many times, the culture is still mostly shrimp (stocked at 50-60/m2) and the fish is just there for improving environment (0.5 fish/m2). Normally herbivorous fish are used which do not east the shrimp - like tilapia or mullet or milkfish. Of course, this means lower stocking density, so less profit, but more sustainable - so long term it is a better strategy and works to prevent diseases like EMS and WSSV and IMNV

马修

Normally we would use 30-31oC for all of larval rearing cycle, but if you suffer from zoea-2 syndrome it is a good idea to increase temperature to 32, 33 or 34oC throughout zoea stage until become Mysis 1 then reduce back down to 30-31oC. This is done to push the zoea through to mysis as soon as possible at high temperature to avoid Zoea-2 syndrome. But you must maintain either 32, 33 or 34 constant day and night (do not allow temperature to fluctuate between day and night)

通常，亲虾我们只使用4个月。因为那以后，它们的繁殖质量就不好了。也就是剪眼后，我们连续使用4个月，然后换一批。我们不会停一段时间，然后继续使用同一批亲虾。

马修

We think white faeces syndrome is probably bacterial cause, togehter withpoor water and soil quality. So improve the environment by water exchange, siphoning wastes and using probiotics in feed (5-10g/kg of feed until gone). Other people use organic acids  at 2-5 g/kg in the diet and some have success using fresh garlic at 10 g/kg crushed up and top-dressed on diet 3-5 diets per day for 2-3 days