Morphological characterization of blue-and-yellow macaw (Ara ararauna) seasonal testicular variations in captivity.

Mariana G Moreira,Renata C Mazaro,Gessica C Sousa,Ana C.S Rebelo,Max V.M Medeiros,Karina Simões,Lucélia G Vieira,Edson J Benetti

doi:10.1590/0001-3765202120190557

Mariana G Moreira, Renata C Mazaro + Show 6 more

Open Access

https://doi.org/10.1590/0001-3765202120190557

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Abstract

The reproduction of monogamous wild birds in captivity it`s difficult and the apparent low fertility in males requires more investigations. The objective of the study was to test the hypothesis that wild bird species in captivity would present low reproductive potential, through the analysis of the morphological characteristics of Ara ararauna testicles, maintained in captivity, correlating them with the climate variations in the Cerrado Biome. For that, testicles were captured in April (dry) and October (rainy). The right and left testicles showed mean weight, gonadosomatic index, longer axis, and volume similar between the dry and rainy season. Only the shorter axis demonstrated higher values during the rainy season. The morphometric variables of the seminiferous tubules have also higher values during the rainy season. By these histological and morphometric characteristics of the seminiferous epithelium we can conclude that, during the rainy season, the testicles were in gonadal recrudescence, which precedes the reproduction phase. During the dry season, the testicles were in the rest phase of the seminiferous epithelium. Therefore, we concluded that the species in captivity, under Cerrado environmental conditions, have kept their reproductive potential, presenting a complete spermatogenic cycle during the rainy season, which can guarantee the species perpetuation.

Highlights

Vertebrates reproduction in under endogenous regulation and is, generally, dependent of environmental factors
The analysis of Ara ararauna biometric aspect, average body weight (g) during the rainy season was from 1095.0g (±20.0), and in the rainy seasons presented 843.3g (±151.7)
The Ara ararauna of the dry season showed average biometric data for weight, longer axis and volumes of the right and left testicle, similar to the data found during the rainy season (p>0.05), but with a statistically significant difference for the variable longer axis of the left testis (Table I)

Summary

Introduction

Vertebrates reproduction in under endogenous regulation and is, generally, dependent of environmental factors. The seasonal reproductive periods are constant, influenced by these factors, where the reproductive organs grow and regress with light, temperature, rainfall index and food availability (Kemp 1973), is subjected to constant variations due to geographical latitude and altitude (Breucker et al 1989). The studies are concentrated in regions that are the closest to the Equator (Hau et al 1998, Hau 2001), where the temperature does not vary much and the rainfall index is very high during the entire year, as opposed to the Cerrado biome, the main area where the Ara ararauna is usually found and that possess well defined periods of dry and rainy seasons.

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