Growth of broad-nosed caiman, Caiman latirostris (Daudin, 1802) hatchlings, fed with diets of animal origin

The study was carried out to evaluate the growth rate of broad-nosed caiman, Caiman latirostris hatchlings, fed on four animal protein diets: (a) dead poultry from a poultry farm; (b) dead piglet from nursery and farrowing house in a swine farm; (c) whole tilapia (Tilapia rendalli e Oreochromis niloticus); and (d) a balanced mixture of a, b, and c sources. Sixteen seven-month old caimans, average weight of 208 g and, 38 cm of total length (TL) were distributed in four treatments. Four groups of four caimans each were placed in cement enclosures inside a greenhouse. Diets were supplied at the average rate of 97.8% +/- 34.8% of the body weight per week (average and standard deviation; wet weight basis). Body mass and total length of caimans were measured every 30 days for six months (Nov. 1995-April. 1996). An analysis of variance with repeated measures was performed. Diets provided suitable growth for weight and TL (mean +/- standard deviation, respectively): (a) 2,157 +/- 743 g and 79.5 +/- 6.9 cm; (b) 1,811 +/- 222 g and 75.7 +/- 1.9 cm; (c) 2,431 +/- 780 g and 80.7 +/- 5.8 cm; (d) 1,683.5 +/- 736 g and 74.5 +/- 7.2 cm. There was no significant effect of diet on weight, but diet effect on TL of hatchlings approached significance (p < 0.10). It is concluded that all diets have good potential, in growth sense, to be used in commercial farms or ranches and for captivity propagation programs of caimans.

Observations on the thermal selection of the pantanal caiman (Caiman crocodilus yacare) hatchlings (Crocodylia: Alligatoridae)

Three options of water temperatures in a thermal gradient that changed from 22 to 35 degrees C were offered to Pantanal caiman (Caiman croocodilus yacare) hatchlings. Animals from two nests were submitted to temperatures during 19 days (Nest 1 -- 20 caimans caught in the nature hours after hatching), corresponding to 1 to 7 observations periods, and 13 days (Nest 2 -- 20 animals obtained by artificial incubation) relative to observation period 8. Caimans remain fasting during experimental period. Hatchlings were allocated in a enclosure containing three styrofoam boxes (120 L) disposed side by side enclosed by wire netting and filled with water to the top. Thus, the animals were free to access the boxes, which temperatures were changed at the end of each observation period to avoid position effects. Air temperature was keep close to 22 degrees C by air conditioning and water temperature was controlled by thermostats. The trial was divided in three phases determined by elimination of the less frequented temperature and its substitution by another temperature. In a first phase of the experiment that contained 1, 2 and 3 observation periods, the thermostats were regulated to 22 degrees C (BoxD), 26 degrees C (BxC) and 32 degrees C (BxA). In phase 2 to 26 degrees C, 29.5 degrees C (BxB) and 32 degrees C, including 4, 5 and 6 periods. In the third phase that included 7 and 8 periods, the thermostats were adjusted to 29.5 degrees C, 32 degrees C and 35 degrees C (BxE). The number of caimans in each box was recorded two to three times a day (8:00, 14:00 and 17:00h) before pointed water temperature. Mean water temperatures (+ standard deviation) and respective caiman frequency means by box/temperature were: Phase 1 (BxD/22.3 +/- 1.2 degrees C - 10.3%; BxC/27.0 +/- 2.4 degrees C - 32.0% and BxA/31.2 +/- 1.1 degrees C - 57.6%); Phase 2 (BxC/26.6 +/- 2.8 degrees C - 13.3%; BxB/29.3 +/- 2.2 degrees C - 27.7% and BxA/31.3 +/- 1.2 degrees C - 59.0%) and Phase 3 (BxB/29.5 +/- 3.6 degrees C - 23.7%; BxA/31.0 +/- 2.2 degrees C - 31.9 and BxE/34.0 +/- 2.2 degrees C - 44.4%). Observing that in the phases 1 and 2 the box with hottest water (CxA) was more frequented. In the phase 3, the difference between higher and smaller frequency straiten to 20.7%, in relation to almost 46.5% in phases 1 and 2, indicating that water temperatures between 29.5 and 35 degrees C resulted in body temperatures more next to the comfort zone, in the experimental conditions.

Biochemical differentiation between enterotoxigenic heat-sensitive and heat-resistant Clostridium perfringens strains

Some biochemical characteristics of 37 enterotoxigenic Clostridium perfringens strains isolated from human feces, ground beef, and soil samples by heat-selection methods and of two NCTC strains were studied. Two different biochemical patterns closely related to the heat resistance of the strains were found. The strains placed into group 1 were trehalose, inositol, and sorbitol negative and synthesized heat-resistant spores, while those placed into group 2 were trehalose and inositol positive and synthesized heat-sensitive spores. Sorbitol fermentation was variable among the strains of this last group. The strains of group 1 were more cellobiose, melibiose, and salicin fermentative than those of group 2. Only the strains placed into group 2 synthesized toxins of sufficient levels for typing. In spite of having been isolated by mild heat treatment of the specimens, two strains showed the same biochemical and toxigenic characteristics of the strains of group 1. The heating of these two strains did not modify their characteristics. We conclude that enterotoxigenic C. perfringens strains showing the two different toxigenic and biochemical patterns are present in the human gut, ground beef, and, probably, in soil. These strains may be differentiated on the basis of their capacity to produce acid from trehalose, inositol, and sorbitol, heat resistance of the spores and grade of toxigenicity. The heat-selection methods used for isolation of C. perfringens strains from different sources exerted a selection of strains from one or another group, but had no influence on their toxigenic and biochemical properties.