2. Materials and methods
2.1. Animals and sample collection
This study was conducted with two adult female Amazonian
manatees (Ti-057 and Ti-060) initially housed in
two round pools (10 m
×
2.5 m depth; 196 m3) in the Laboratory
of Aquatic Mammals at the National Institute of
Amazonian Research (INPA, Manaus, AM, Brazil). Both animals
were over 25 years old and had already conceived at
least one calf each in captivity. The animals were fed with
forage grass (Brachiaria mutica), lettuce, cabbage, and other
vegetables at a level greater than or equal to 8% of their
body weight per day. Water from artesian wells circulated
through the pools constantly, and the water temperature
varied between 27 ◦C and 29 ◦C.
Considering the possible existence of reproductive
seasonality in the species, salivary samples were collected
daily for 12 consecutive weeks between March and June
for two consecutive years. To facilitate the sample collection
procedure, the animals were kept in two holding pools
(3.5 m
×
2.5 m
×
1.5 m depth; 13 m3) for the entire experimental
period, and all sample collections were conducted
between 0800 and 0900 h. For sample collection, the pool
was drained, and the saliva (∼0.5 mL) was collected from
the oral mucosa using a metal spoon. Samples visually contaminated
with feces were discarded. All samples were
frozen at
−20 ◦C until assayed.