Temporal responses in energy expenditure and respiratory quotient following feeding in the muskox: influence of season on energy costs of eating and standing and an endogenous heat increment
Seasonal energy metabolism was investigated in young (2- to 3-year-old) muskoxen (Ovibos moschatus) during the winters of 1994 (JanuaryApril) and 1996 (January) and summer of 1995 (July and August). Energy expenditure (EE) increased 35%42% following a meal of chopped brome hay (Bromus inermis) and...
Published in: | Canadian Journal of Zoology |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
2003
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Subjects: | |
Online Access: | http://dx.doi.org/10.1139/z03-133 http://www.nrcresearchpress.com/doi/pdf/10.1139/z03-133 |
Summary: | Seasonal energy metabolism was investigated in young (2- to 3-year-old) muskoxen (Ovibos moschatus) during the winters of 1994 (JanuaryApril) and 1996 (January) and summer of 1995 (July and August). Energy expenditure (EE) increased 35%42% following a meal of chopped brome hay (Bromus inermis) and declined as a double-exponential process over 8 h. The mean energy cost of eating (321 and 361 J·g dry matter 1 ) was lower in winter than in summer, and declined with body mass (BM) (r 2 = 0.58). The mean energy cost of standing was 21% (SE = 2.7%) higher than that of bedding. Prefeeding energy expenditure (EE p ) was 26% higher in summer than in winter. An endo genous heat increment, measured as EE p EE, at 7-8 h post feeding was lower (P < 0.001) in winter than in summer (39 and 58 kJ·kg BM 0.75 ·d 1 , respectively). Mean cumulative EE (minus activity costs) for 8 h post feeding was 124 (SE = 4) and 148 (SE = 4) kJ·kg BM 0.75 (P < 0.001) in winter and summer, respectively. Respiratory quotients (RQs) >1 were recorded during feeding in winter and a mean RQ of 0.9 was recorded in summer. Seasonal EE p , postfeeding EE, and RQ are consistent with a low cost of maintenance metabolism in winter and an increased requirement for productivity in summer. |
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