PLANT PRODUCTS IN COMPOUNDED DIETS ARE EFFECTIVELY UTILIZED BY AMERICAN ALLIGATOR Alligator mississippiensis

Alligator farming is an established aquaculture industry in Louisiana with a current farm-gate value of $78 million. Producers feed animal-based diets largely devoid of plant products because it is expected that plant materials will not be effectively utilized by the alligator, a natural carnivore. We conducted the present study with diets composed primarily of plant products to test the ability of the alligator to utilize a plant-protein based diet.

A previous short-term study demonstrated that growth performance of alligators fed a plant-based, 45% digestible protein (DP) diet composed of soybean meal, wheat gluten, menhaden fish meal and yellow corn, with available essential amino acids (EAA) similar to EAA:lysine ratios in alligator whole body and digestible energy-to-protein ratio of 37.7 kJ DE/g DP, was statistically equivalent to that of alligators fed a higher-protein commercial formulation used by most producers. The present study compared this plant-based diet with two commercial diets in a 10-month growth trial under simulated production conditions.

Hatchling alligators (mean length and weight of 27.2 ± 1.5 cm and 57.4 ± 6.9 g) were stocked, 8 animals per tank, in 24, 2.98-m² flow-through, polyethylene tanks. Water depth was maintained at 0.3 m and water temperature at 30-31°C. Alligators received one of three dietary treatments: 56/50 - a 56% crude protein (CP) commercial diet fed for 3 months, followed by a 50% CP commercial diet fed for 7 months; 56/45 - the 56% CP diet fed for 3 months, followed by the 45% DP plant-based diet fed for 7 months; or 45/45 - the 45% DP diet fed for 10 months. Results indicated that mean length and weight (L/W) of alligators fed 45/45 (88.2 ± 4.5 cm and 1835.9 ± 265.2 g) was significantly lower than L/W of animals fed 56/50 (95.0 ± 4.5 cm and 2359.1 ± 320.7 g) but L/W of alligators fed 56/45 (92.6 ± 3.0 cm and 2167.9 ± 263.1 g) was not significantly different (P > 0.05) from L/W of alligators fed 56/50 or 45/45, suggesting that protein content of the diet fed during the first 3 months was a primary factor affecting growth. The range of growth responses among animals in all three treatment groups - median L/W of 90 cm and 1868 g for alligators fed 45/45; 95 cm and 2289 g for those fed 56/45; and 97.5 cm and 2439 g for animals fed 56/50 - showed that some better-performing individuals fed 45/45 and 56/45 also grew as large as animals fed 56/50. Results indicated that the American alligator can effectively utilize plant products in a compounded diet and additional research on the use of selected plant products in alligator feeds is warranted.