A MULTI-STRAIN PROBIOTIC, RED DRUM Sciaenops ocellatus, AND DIGESTA: THE NITTY-GRITTY ABOUT CHANGES SEEN OVER TIME

Wren A. Busby* and Ione Hunt von Herbing
Marine Conservation and Aquatic Physiology Laboratory
Biological Sciences Department
University of North Texas (DIB Cluster)
Denton, Texas 76201
wrengafford@my.unt.edu
 

Bacteria are important to a functional digestive system, and the use of probiotics, defined as "good bacteria," has become more common in the last 10 years to help re-establish the gut flora after treatment of antibiotics. Red drum (Sciaenops ocellatus) a commercially important carnivorous marine fish, that has a short gut and rapid food transport. Rapid digestion and assimilation rates are important to rapid growth. The goals of the current study were to determine the effects of probiotics on growth & mortality rates, food conversion ratios (FCRs), behavior, and to evaluate gut health.

A 56-day feeding trial was conducted in 20 gallon tanks inside a temperature controlled room at 27°C. Juvenile red drum from APEKS Aquaculture® (Palacios, Texas) were measured and weighed at the start of the experiment. Experimental tanks were divided into: 1) control, 2) probiotics recommended dosage (1.0x108 CFU/g) only through day 28, and 3) probiotics recommended dosage (1.0x108 CFU/g) through day 56. Probiotics selected was Primilac® a multi strain mixture containing Lactobacillus acidophilus, Lactobacillus casei, Bifido bacterium bifidium, Enterococcus faecium. The probiotic was added to treatment tanks daily along with the fish meal, while controls were only fed fish meal.

After 56 days, the trial group treated with probiotics till day 56 showed an increased growth of 33.7% over the control, probiotics till day 28 wasn't significantly different at 33%. The FCR for probiotics showed that after day 14 until day 28, and to day 56 required less than a gram (FCRs ranged from 0.75g feed / 1g of fish mass up to 0.25g feed / 1g of fish mass). And mortality rates decreased from day 7 (2%) to day 21 (0%) in the probiotics' tanks after which there was no more mortality. For controls, weekly mortalities ranged from >3% to < 1% until the 5th week, when the amount of fish was reduced to about 1 fish/gallon of seawater. This shows a significant advantage with the use of probiotics.