EXPERT TOPIC WHITE SHRIMP
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WHITE SHRIMP
Improving White Shrimp productivity on a Mexican farm by Dr Ron Cravens, Amlan International
alibrin-ZÂŽ has been proven to bind a broad spectrum of biotoxins, both mycotoxins and bacterial toxins. Prior published research using Calibrin-Z showed that alpha and NetB toxins from Clostridium perfringens, which causes necrotic enteritis in chickens, could be controlled in vitro and in vivo. Then research reported at the World Aquaculture Society conference in 2015 showed that Calibrin-Z bound the two major toxins from Vibrio parahaemolyticus that cause Early Mortality Syndrome (EMS) and ameliorated their effects on juvenile shrimp. Testing in Arizona showed that feeding Calibrin-Z increased the survival rate of shrimp from five percent (Challenged Control) to 84 percent (Challenge + Calibrin-Z) during EMS challenge studies. Therefore, a study was conducted to determine the value of adding Calibrin-Z to shrimp feed used on a commercial facility.
Research Methods
Nine million juvenile shrimp in nine 5-hectare ponds located in Sonora, Mexico were used in this study. The ponds were at high risk of having an outbreak of EMS during the trial period. The shrimp in four of the ponds were fed Calibrin-Z (0.5% inclusion), and their results were compared to those of five ponds of shrimp that were fed a diet supplemented with a mixture that was felt to help control EMS. The study was conducted from August to November 2016, typically the last shrimp production batch of the year for this area. The feed formulation (other than the additives that were being compared), immunisation programme, and management were the same between all the ponds. The shrimp were fed multiple times per day and feed consumption of each pond was recorded weekly
to calculate the feed conversion ratio at the end of the study. Mortality, weather conditions, and water quality were monitored for each pond. No outbreak of Early Mortality Syndrome was observed during the study and survival rate was similar between the two treatments. Shrimp were harvested when they reached an average of 14g. Days on feed and shrimp weights were measured on the day of harvest.
Results
Shrimp fed Calibrin-Z reached market weight six days sooner (84 vs. 90 days) than those on the Control group. This is because feeding Calibrin-Z increased weekly weight gain – 1.16 g/shrimp for those fed Calibrin-Z compared to only 1.07g/shrimp for those in the Control group, an 8.4 percent improvement (Figure 1). That weight came using less feed; at harvest the feed conversion ratio for shrimp fed Calibrin-Z was 9.2 percent better, with 1.52 feed: gain for those on the Control compared to 1.38 when Calibrin-Z was fed (Figure 2). Previous research showed that feeding Calibrin-Z would control biotoxins that damage the digestive tract. The improvements in feed conversion seen in this study indicate that feeding Calibrin-Z resulted in shrimp with a healthier gut environment; and thus, improved productivity and profitability.
Return-on-investment
The Return-On-Investment from adding Calibrin-Z in this instance was 6:1. The calculation is shown in Table 1. Costs were based upon the values at the time in Mexico. Adjustments were made so that harvest was at a consistent 90 days. The extra cost of the additives in the Control diet was not included in the calculation, therefore, the 6:1 was a minimal return-oninvestment.
30|September2017-InternationalAquafeed