Body size and gastrointestinal morphology of nutria (Myocastor coypus) reared on an extensive or intensive feeding regime

Larger Than Life? Body Mass Records of Zoo-Managed Giant Anteaters (Myrmecophaga tridactyla)

It has been suggested repeatedly that zoo-kept giant anteaters (Myrmecophaga tridactyla) have higher body masses than their free-ranging conspecifics. Here, we assess this hypothesis by comparing body mass data of 184 female and 173 male individuals kept in zoos to published and unpublished data of free-ranging animals (n = 215). In zoos, the average adult body mass of all individuals was 45.9 ± 9.6 kg (range 19.2-72.6 kg), whereas body mass for free-ranging specimens was 33.0 ± 2.3 kg (21-45.5 kg). Among those zoo animals in which a sufficient number of subsequent intra-annual measures had been taken, we assessed visually whether regular, annual fluctuations in body mass were evident. We observed regular, likely seasonal, cycles in body mass, which (i) may be plausibly attributed to ambient temperature changes that affect the body temperature of anteaters, and (ii) would likely not have occurred if the animals were affected by obesity. Additionally, we explain our hypothesis that in the case of giant anteaters, the discrepancy in body mass between natural habitats and zoos most likely is not indicative of a generally obese population in zoos, as is typically concluded in the case of similar comparisons in primates, but represents an unleashing of the full growth potential of the species by conditions of optimal energy and nutrient provision. Future recording of not only body mass but also body dimensions is recommended to better compare the body condition of free-ranging and zoo-managed individuals.

Weigh and see-Body mass recordings versus body condition scoring in European zoo elephants (Loxodonta africana and Elephas maximus)

Regular body mass (BM) monitoring plays a key role in preventative health care of zoo animals. In some species, including African (Loxodonta africana) and Asian elephants (Elephas maximus), the process of weighing can be challenging, and alternative methods such as visual body condition scoring (BCS) have been developed. We investigated the temporal development of both parameters regarding correlation patterns between them, and their suitability as monitoring measures in dependence of an elephant's life stage. While BM is more suitable in calves and juveniles under the age of 8 years, both BM and BCS are considered equally reliable in adult elephants. In elephants over the age of 40 years, BCS might be more suitable for assessing the physical status. Independent of species and sex, juvenile zoo elephants grow in BM nearly linearly with age, and reach a higher BM at an earlier age compared with conspecifics of free-ranging and semi-captive populations in the countries of origin. The BCS typically remains constant during this life stage, seemingly unaffected by growth. In adult animals, breeding females have a lower BM and BCS than nonbreeders, and BM and BCS typically indicate fluctuations in the same direction. In geriatric elephants (>40 years) a drop in BCS occurs commonly, while BM may even increase in this life stage. We recommend regular body mass recording in zoo elephants to enhance our knowledge of body mass development and allow the formulation of objective practical recommendations. BCS presents a valuable and simple tool for complementary monitoring of an elephant's condition, especially in adult and geriatric individuals.