Use of fresh bull and hog testis in Use of fresh bull and hog testis in sex reversal of Nile tilapia frysex reversal of Nile tilapia fry

Daniel Meyer, Marco GuevaraDaniel Meyer, Marco GuevaraWillie Chan and Claudio CastilloWillie Chan and Claudio Castillo

Funding for this research was provided by theFunding for this research was provided by the

Aquaculture Aquaculture Collaborative Research Collaborative Research

Support ProgramSupport Program

The Aquaculture CRSP is funded in part by United States Agency for The Aquaculture CRSP is funded in part by United States Agency for International International

Development (USAID) Grant No. LAG-G-00-96-90015-00 and by Development (USAID) Grant No. LAG-G-00-96-90015-00 and by participating institutions.participating institutions.

IntroductionIntroduction Modern techniques for culturing tilapiaModern techniques for culturing tilapia MT is synthetic productMT is synthetic product Increasing demand for organic foodsIncreasing demand for organic foods Little published work on use of natrual Little published work on use of natrual

sources of testosterone in sex reversalsources of testosterone in sex reversal

ObjectiveObjective

Evaluate the use of fresh bull and hog Evaluate the use of fresh bull and hog testis in the sex reversal of Nile tilapia testis in the sex reversal of Nile tilapia Oreochromis niloticus Oreochromis niloticus fryfry

Location:Location:

Aquaculture Station at the Escuela Agrícola Panamericana, Honduras

FishFish- FertilFertilee eggs collected from incubating females eggs collected from incubating females- Artificial incubationArtificial incubation

FishFish

Fry (Fry (± ± 8 mm) were treated in 20 L plastic buckets in lab8 mm) were treated in 20 L plastic buckets in lab Continuous aeration, daily cleaning and water exchangeContinuous aeration, daily cleaning and water exchange After 36 days fry transferred to cylindrical net enclosures (3 After 36 days fry transferred to cylindrical net enclosures (3

mm mesh) located in a greenhouse for ongrowing to mm mesh) located in a greenhouse for ongrowing to > > 50 50 mmmm

Preparation of meat productsPreparation of meat products fresh testis cut and processed with grinderfresh testis cut and processed with grinder salt added salt added dried at 32dried at 32°° C C stored frozenstored frozen purchased meat meal from local supplierpurchased meat meal from local supplier

Water qualityWater quality

Dissolved oxygen and water temp a.m. Dissolved oxygen and water temp a.m. and p.m.and p.m.

Experimental units cleaned with syphon Experimental units cleaned with syphon every other dayevery other day

Fry grown to a total length Fry grown to a total length ± ± 50 mm50 mm Gonads removed and observed 50XGonads removed and observed 50X

Sex determination thru microscopySex determination thru microscopy

Sex determination via microscopySex determination via microscopy

Male fry = No presence of oocytes, granular texture of the gonad

Fuente Popma and Green

Female fry = oocytes observed at varios stages of development

Fuente Popma and Green

Experimental design: Experimental design: • Three treatments:Three treatments:

• bull testisbull testis• hog testishog testis• meat mealmeat meal

• Four repetitions of eachFour repetitions of each• ChiChi22 for evaluating treatment effectiveness for evaluating treatment effectiveness• ANOVA with survival resultsANOVA with survival results• Statistical Analysis System Statistical Analysis System (SAS(SAS®® 2003) 2003)

Results and discussionResults and discussion

Water qualityWater quality: dissolved oxygen: dissolved oxygen

Figure 1. Average daily dissolved oxygen concentration, Zamorano, Honduras. Water in all containers was aerated continuously.

0

2

4

6

8

10

12

0 10 20 30 40 50 60 70 80Días

mg/L

H. CarneT. ToroT. Verraco

Wet lab Greenhouse

Figure 2. Average daily water temperature for 20 L buckets and net enclosures during a 71-day feeding trial, Zamorano, Honduras.

0

5

10

15

20

25

30

35

0 10 20 30 40 50 60 70 80

Días

Deg

rees

C

Meat meal Bull testis

Hog testis

Wet lab GreenhouseWet lab

Water quality: temperatureWater quality: temperature

Figure 3. Number of fry surviving based on original 200 fish for each treatment.

0

50

100

150

200

250

0 10 20 30 40 50 60 70 80Days

Nu

mb

er

of

fry

Meat meal

Bull testis

Hog testis

No electricity on night of day 20!

Fry survival by environmentFry survival by environment

CultureCulture environmentenvironment

CultureCulture

daysdays

Initial Initial populationpopulation

FinalFinal populationpopulation

%%

survivalsurvival

Wet labWet lab

(20 L buckets)(20 L buckets)

1 thru 361 thru 36 600600 241241 40.2%40.2%

GreenhouseGreenhouse(net enclosures)(net enclosures)

36 thru 7136 thru 71 241241 219219 90.9%90.9%

Overall fry survival for 71-day long experiment was 36.5%.

Fry survival by environmentFry survival by environment

Low DO detected after electrical black-out Low DO detected after electrical black-out (on day 20 of experiment)(on day 20 of experiment)

100% meat based feeding regime 100% meat based feeding regime (tilapia is (tilapia is primarily an herbivore)primarily an herbivore)

Small initial size of fish Small initial size of fish (mortality observed 20 days (mortality observed 20 days after stocking)after stocking)

Low survival rates reported in previous Low survival rates reported in previous studiesstudies

Haylor, G. S.; A. B. Pascual. Haylor, G. S.; A. B. Pascual. 1991. Effect of using ram testis in a fry diet for Oreochromis niloticus (L.) on 1991. Effect of using ram testis in a fry diet for Oreochromis niloticus (L.) on growth, survival and resultant phenotypic sex ratio. Aquaculture and Fisheries Management 22: 265-268.growth, survival and resultant phenotypic sex ratio. Aquaculture and Fisheries Management 22: 265-268.

Phelps, R.P. 2001. Phelps, R.P. 2001. Sex Reversal: the directed control of gonodal development un tilapia, pages 35-60. Sex Reversal: the directed control of gonodal development un tilapia, pages 35-60. En En D.E.Meyer (editor). Memoria 6to simposio Centroamericano de Acuacultura. Asociación Nacional de D.E.Meyer (editor). Memoria 6to simposio Centroamericano de Acuacultura. Asociación Nacional de Acuicultores de Honduras y PD/A CRSP, Honduras.Acuicultores de Honduras y PD/A CRSP, Honduras.

Fry survival by treatmentFry survival by treatment

TreatmentTreatment

Initial numberInitial number fry/repetitionfry/repetition

Final numberFinal number

fry/repetitionfry/repetition

%%

fry survivalfry survival

Meat mealMeat meal 5050 2424 4848aa

Bull testisBull testis 5050 1616 3232bb

Hog testisHog testis 5050 1515 3030bb

Unable to explain observed difference in survival by treatment!

Growth of the fry during 71 daysGrowth of the fry during 71 days

AverageAverage

body weight (g)body weight (g)

AverageAverage

body length (cm)body length (cm)

TreatmentTreatment InitialInitial FinalFinal InitialInitial FinalFinal

Meat mealMeat meal 0.010.01 3.48 3.48 ± ± 0.600.60 0.80.8 4.8 4.8 ± ± 0.50.5

Bull testisBull testis 0.010.01 4.13 4.13 ± ± 0.480.48 0.80.8 5.7 5.7 ± ± 0.30.3

Hog testisHog testis 0.010.01 3.88 3.88 ± ± 0.160.16 0.80.8 5.5 5.5 ± ± 0.20.2

Percent of male fishPercent of male fish

TreatmentTreatment

% male% male

fishfish

Meat mealMeat meal 58 58 ± 4.9± 4.9

Bull testisBull testis 87 87 ± 5.6± 5.6

Hog testisHog testis 83 83 ± 7.7± 7.7

Chemical analysis of testisChemical analysis of testis

Processed meatProcessed meat

productproduct

TestosteroneTestosterone

levellevel

Fresh ground bull testisFresh ground bull testis 18.8 ppm18.8 ppm

Fresh ground hog testisFresh ground hog testis 20.4 ppm20.4 ppm

Testosterone levels in dried testis would be > 60 ppm.

ConclusionsConclusions

Bull and hog testis were effective to Bull and hog testis were effective to produce mostly male fry of tilapia produce mostly male fry of tilapia beginning sex reversal at a small total beginning sex reversal at a small total body length (body length (± 8± 8 mm) mm)

Low survival of fry attributed to water Low survival of fry attributed to water quality problems and possible nutritional quality problems and possible nutritional deficiency.deficiency.

In green water survial of fry was In green water survial of fry was > > 90%!90%!

RecomendationsRecomendations

Attempt to use testis for sex reversal in outdoor Attempt to use testis for sex reversal in outdoor tanks with green water.tanks with green water.

Use freeze-drying of testis for better preparation Use freeze-drying of testis for better preparation and stroageand stroage

Develop a methodology for extracting hormone Develop a methodology for extracting hormone from fresh testis from fresh testis

Fin