Digesta passage rates in the Florida manatee (Trichechus manatus latirostris)

Abstract

The Florida manatee, Trichechus manatus latirostris (Sirenia: Trichechidae), is an herbivorous marine mammal found within coastal areas throughout the state of Florida, which feeds on both fresh and salt water sea grasses. Manatees, like other Sirenians, are a tropical species with little tolerance for water temperatures below 20 degrees C, rely on a relatively poor nutritional food source, and have a low metabolic rate. Although manatees are hindgut fermenting herbivores, they are very efficient at extracting nutrients from the plants on which they feed. Slow passage rates of digesta have been suggested to be a factor in this increased efficiency. Two studies monitored the digesta passage times and mixing of particulate digesta within the manatee digestive tract using MicroGrits colored corncob grit as a fecal marker. Fecal samples were collected subsequently from four manatees in Study 1 and 3 manatees in Study 2, grit pieces removed, counted, and measured. The digesta passage times ranged from 6 and 10 days in Study 1, and 4.3 and 8.3 days in Study 2, supporting data presented in previous studies. When two different colored markers were administered on sequential days, minimal to no mixing was seen in recovered feces, suggesting that the digesta from a given day traveled through the tract as a bolus. Less than 1% of the marker fed was recovered and we hypothesize that perpendicular folds of the large intestine may be the major contributing factor, with pieces being retained and eventually digested. Zoo Biol 26:503-515, 2007. (c) 2007 Wiley-Liss, Inc.

Carbon and nitrogen stable isotope turnover rates and diet–tissue discrimination in Florida manatees (Trichechus manatus latirostris)

“…It is also possible that food passage time impacts on turnover rate [as discussed by Post (Post, 2002)]. Manatees use hindgut fermentation and have a passage rate through the digestive tract of 146-147 h (Lomolino and Ewel, 1984;Larkin et al, 2007). This rate is consistent with that of the dugong, another sirenian [145-166 h (Lanyon and Marsh, 1995)], but much slower than those of other large hindgut fermenters such as elephants [21-46 h (Rees, 1982)], horses [26-27 h (Rosenfeld et al, 2006)] and rhinoceros [61 h (Clauss et al, 2005)].…”

Digestive Efficiencies of Ex Situ and In Situ West Indian Manatees (Trichechus manatus latirostris)

“…Manatees are hindgut fermenters but are unusual in that they combine this hindgut fermentation with a prolonged digesta transit time (Burn 1986;Reynolds and Rommel 1996). Numerous authors (e.g., Lomolino 1977;Best 1981;Burn 1986;Reynolds and Rommel 1996) have noted that this slow passage (up to 7 d; Larkin et al 2007) should aid in their ability to digest the generally low-quality (i.e., relatively high crude fiber, low crude protein, and low caloric value) food they consume.…”

“…For released animals, fecal samples were collected on the day of release and during routine scheduled health assessments at 3, 6, and 12 mo postrelease. Based on average gut transit times (Larkin et al 2007), any fecal sample collected from a manatee ≤7 d after a diet change was considered to represent the original diet category, and any sample collected ≥10 d after a diet change was considered to represent the new diet.…”

“…A longer MRT is considered to be an advantage for species that consume food that is either hard to digest or low in nutritional value (Robbins 1993). Manatees utilize hindgut (colonic) fermentation (Reynolds 1980;Best 1981;Snipes 1984), and while there is a paucity of data on the MRT of manatees, the limited data that are available for sirenians suggest that they have an MRT that is significantly longer than in most other species of similar body mass (Steuer et al 2011, Müller et al 2013, ranging from 120 to 168 h (e.g., Lanyon and Marsh 1995;Larkin et al 2007). …”

Tempo de passagem de duas dietas no trato gastrointestinal do peixe-boi da Amazônia Trichechus inunguis (Natterer, 1883) em cativeiro

“…Este intervalo de tempo é reforçado por Itavo (1995) que encontrou um tempo de passagem de 114 a 161 horas, dependendo do tipo de alimento ingerido. Esse tempo de passagem se assemelha ao tempo de passagem encontrado em dugongos (Dugong dugon), que varia de 146 a 166 horas (Lanyon e Marsh 1995) e no peixe-boi da Flórida (Trichechus manatus latirostris) com cerca de 6 a 10 dias (Larkin et al 2007). O tempo de passagem lento faz com que T. manatus seja um dos herbívoros com maior eficiência de digestão de celulose dentre os mamíferos herbívoros (Burn 1985).…”