(602s) Engineering Alligator Diets to Increase Reproductive Performance of Alligator Eggs from a Captive Population

Authors: 
Mikolajczyk, A., University of Louisiana at Lafayette
Holmes, W., University of Louisiana at Lafayette
Zappi, M., University of Louisiana at Lafayette

Breeding of alligators in captivity is essential for conservation and commercial purposes, but a major problem of embryonic deaths exists. While there has been significant progress in the captive propagation of young alligators and other crocodilians for purposes of farming and conservation, there has been a notable lack of success with regard to breeding alligators.  Specifically, captive alligators typically exhibit a much lower hatch rate in comparison with wild alligator eggs. Eggs from captive alligators commonly display a hatchability of 50 percent in comparison with a hatchability of wild type having 95 percent.  The relationship between the nutrients in the maternal diet on reproductive performance – egg production and hatchability- of avian and reptiles is well-established. Studying eggs that were incubated 34 days, researchers demonstrated substantial differences in the fatty acid composition of eggs from captive and wild alligators.  These researchers suggested that these differences were a major cause of embryonic mortality in the captive embryos.

The differences in fatty acid composition demonstrated by these researchers indicate an overall increase in ω-6 fatty acids at the expense of ω -3 fatty acids.   Specifically and most importantly, the decrease in the long chain ω-3 polyunsaturated fatty acids (PUFAs) is a problem because of their important role in embryonic development.  The results presented by led researchers to suggest supplementation of the diet of captive breeders as a means to improve embryonic success and hatchability of eggs from captive breeders.  Specifically, the major goal would be to increase the dietary source w-3 long chain polyunsaturated fatty acids, including DHA. 

Alligators from T-Bois Alligator Farm in LaRose, Louisiana depends on commercially produced alligator feeds currently used by most alligator farmers, is produced by Cargill, Inc. Two commercially produced feeds were used in this analysis.

Eggs from T-Bois Alligator Farm in LaRose, Louisiana were collected approximately three weeks after nesting and recorded with a GPS location. A nesting map was developed to determine proximity to feeding sites. Total number of eggs, fertile, infertile, cracked, or otherwise damaged were recorded at collection. Eggs were incubated using the facilities and standard incubating procedures at the T-Bois farm. Once hatched, number of eggs hatched were recorded.  Four fertile eggs from 16 different nests in each diet was collected for laboratory analysis. Physical characteristics of the eggs were measured including length, width, shell thickness, total weight, yolk weight, and eggs shell weight. Egg yolk was homogenized and lipids were immediately extracted by the Folch method. Total lipid weight was determined gravimetrically and fatty acids were analyzed on a gas chromatography-mass spectrometry using the FAME method. Fatty acid profiles of the two feeds were also compared to wild eggs collected from Rockefeller Refuge. To correctly distinguish eggs from each diet, the use of pigmentation will be added into the test diet to pigment the egg yolk. This study dramatically increased the targeted ω -3 and ω -6 fatty acids. By performing this initial screening of fatty acid content of maternal diet and egg yolks this could potentially aide in the development of a commercially produced feed which could increase the reproductive performance of captive alligators.