Modelling the nutritional ecology of ungulate herbivores: evolution of body size and competitive interactions

Illius, A.W., and Gordon, I.J. (1992) Modelling the nutritional ecology of ungulate herbivores: evolution of body size and competitive interactions. Oecologia, 89 (3). pp. 428-434.

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A simulation model is used to quantify relationships between diet quality, digestive processes and body weight in ungulate herbivores. Retention time of food in the digestive tract is shown by regression to scale with W⁰·²⁷, and to be longer in ruminants than in hindgut fermenters. Allometric relationships between whole gut mean retention time (MRT, h) and weight (W) were: MRT = 9.4 W⁰·²⁵⁵ (r² = 0.80) for hindgut fermenters and MRT = 15.3 W⁰·²⁵¹ (r² = 0.76) in ruminants. Longer retention of ingesta by large-bodied ruminants and hindgut fermenters increases digestive efficiency relative to small animals and permits them to survive on lower-quality foods. Compared with ruminants, hindgut fermenters' faster throughput is an advantage which outweighs their lower digestive efficiency, particularly on poor quality foods, provided that food resources are not limiting. This suggests that the predominance of ruminants in the middle range of body weights results from their more efficient use of scarce resources under conditions of resource depletion. Considering only physical limitations on intake, the model shows that the allometric coefficient which scales energy intake to body mass is 0.88 in ruminants and 0.82 in hindgut fermenters. The advantages of large body size are countered by disadvantages where food quantity is limited, and we suggest that the upper limit to ungulate body size is determined by the ability to extract nutrients from feeding niches during the nadir of the seasonal cycle of resource quality and abundance.

Item ID: 42639
Item Type: Article (Research - C1)
ISSN: 1432-1939
Keywords: ruminant, hindgut fermenter, nutritional ecology, evolution, body size
Date Deposited: 10 Feb 2016 07:43
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070204 Animal Nutrition @ 50%
06 BIOLOGICAL SCIENCES > 0608 Zoology > 060806 Animal Physiological Ecology @ 50%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830399 Livestock Raising not elsewhere classified @ 50%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
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