Hormone treated feed preparation
Why hormone treated feed required?
During courtship displays, mature male tilapia waste a lot of energy to build their breeding nests, displaying and protecting their territory. Female tilapia expend a lot of energy on egg production, and incubating eggs and protecting their larvae, which is not used for their growth. If breeding is stopped this wasted energy is used for tilapia growth.
Additionally male tilapia grow about 20-30%
faster than female tilapia. For this reason male tilapia fry are preferred for stocking in grow-out tilapia production systems. The most commonly used commercial method for tilapia sex-reversal is to feed the tilapia fry with feed treated with 17-α methyl testosterone hormone from egg yolk absorption for 21 days at a dose of 60 ppm. This is equivalent to adding 60 mg of hormone to 1 kg of feed.
The hormone is first dissolved in at least 95% ethyl alcohol solution, which acts
as a solvent and dissolves the hormone, which does not dissolve in water. The
prepared standard hormone stock solution can be stored for 6 months in a fridge
at 4° Celsius.
The standard hormone stock solution is then mixed into high quality powdered fish meal or a commercial grade high quality powdered
nursing feed.
Conducted correctly the 21 day sex-reversal process should yield fry which are
at least 99% male.
17-α methyl testosterone hormone stock solution preparation
➢ Put on latex gloves and a face mask before working with the hormone
➢ Carefully weigh out 1 g (or 1000 mg) of 17-α methyl testosterone
hormone
➢ Measure out 2 liter or 2,000 ml of at least 95% ethyl alcohol into
a suitable glass container with a top
➢ Dissolve 1 g of hormone into the 2 liter of
at least 95% ethyl alcohol
➢ Put the top on the container and shake the mixture for several minutes
until all the hormone is fully dissolved in the ethyl alcohol
➢ The standard stock solution bottle should be carefully labelled and put
in a fridge at 4° - 6° Celsius. Kept cool and away from direct sunlight the
standard stock solution can be stored for up to 6 months (180 days).
To prepare 2 kg of hormone treated feed for tilapia fry sex-reversa
➢ Measure 240 ml of, previously prepared, 17-α methyl testosterone
hormone stock solution into a spray bottle.
➢ weight 2 kg of powdered fish meal or commercial grade high quality
powdered nursing feed.
➢ The hormone solution can be mixed evenly with the feed by hand sprayer
➢ Keeping spraying and mixing until all the hormone solution has been
added
➢ After all the hormone solution has been sprayed over the feed and it has
been thoroughly mixed
➢ Dry the treated hormone feed at room temperature
➢ When dry the feed can either be used immediately or the hormone
treated feed can be kept in a labelled, sealed plastic bag or plastic box and can be stored in a refrigerator at 4° - 6° Celsius for up to 21 days.
Sex-reversal treatment (SRT) feed application
Feeding rates:
Days 1-5: 15.6 g per day
Days 6-10: 32.6 g per day
Days 11-15: 54 g per day
Days 16-21: 89 g per day
All male tilapia production
[ Ссылка ]
