Jc. Randolph et al., NUTRITIONAL-REQUIREMENTS FOR REPRODUCTION IN THE HISPID COTTON RAT, SIGMODON HISPIDUS, Journal of mammalogy, 76(4), 1995, pp. 1113-1126
To better understand resource allocation in the herbivore Sigmodon his
pidus, nutritional requirements for reproduction were determined. Adul
t female cotton rats were fed Purina (R) #5001 Laboratory Chow ad lib
in the laboratory. They and their progeny were sacrificed at either 10
, 20, 24, or 26 days after breeding, at birth (27 days), or at weaning
(39 days). Protein, lipid, and element concentrations in body tissues
of pregnant females were constant. From birth to weaning, protein con
centration in lactating females increased and lipid concentration decr
eased, whereas no concentration of elements changed significantly. In
progeny, concentration of protein, K, Na, Fe, Zn, and Cu declined sign
ificantly, while concentration of lipids, Ca, P, Mg, Mn, and energy in
creased significantly from birth to weaning. An energy and mass-balanc
e analysis indicated that laboratory chow easily met nutritional requi
rements for reproduction. This analysis was used to estimate minimum n
utritional requirements for reproduction in S. hispidus. A second ener
gy and mass-balance analysis using a natural diet indicated that prote
in and phosphorus ingestion by adult females was lower during autumn a
nd winter than required for production of a litter. Thus, protein and
phosphorus are critical dietary components that may limit reproduction
in S. hispidus under field conditions.