The effects of dietary protein content on growth and maturation in deer mice

Abstract

Growth and female maturation appear to be limited by the availability of dietary protein in natural populations of deer mice (Peromyscus maniculatus borealis) in the Kananaskis Valley, Alberta. We examined the effects of dietary protein content on nestling growth rates and sexual maturation of female deer mice in two laboratory experiments. In the first, mice whose mothers were fed a low-protein mixture of sunflower seeds and oats (14% protein) exhibited slow growth prior to weaning and those fed high-protein cat food (30% protein) postweaning showed compensatory growth. Preweaning but not postweaning diet quality affected the proportion of females who were sexually mature at 42 days of age. Therefore, while deficient nestling growth can be compensated for, the effects of a low-quality maternal diet during lactation may have lasting effects on the maturation of female offspring. In the second experiment, mice raised on isocaloric diets of 14, 20, and 30% protein did not differ in growth as nestlings or juveniles. Differences among the three diets in the proportion of mature females at 42 days did not correspond to dietary protein levels as predicted. Dietary protein content from 14 to 30% appear to be sufficient for juvenile mice raised in captivity.Résumé : La croissance et la maturation des femelles semblent tributaires de la disponibilité des protéines alimentaires chez les Souris sylvestres (Peromyscus maniculatus borealis) de la vallée de Kananaskis, en Alberta. Nous avons étudié les effets du contenu en protéines du régime alimentaire sur les taux de croissance des jeunes femelles au nid et sur leur maturation sexuelle au cours de deux expériences en laboratoire. Dans la première, les jeunes femelles nées de mères nourries d'un mélange de graines de tournesol et d'avoine, à faible contenu en protéines (14%), ont subi une croissance lente avant le sevrage et celles qui ont reçu un régime constitué de nourriture pour chats, riche en protéines (30%), après le sevrage ont subi une croissance compensatoire. La qualité du régime alimentaire avant le sevrage a influencé la proportion de femelles parvenues à maturité à l'âge de 42 jours, mais le régime alimentaire après le sevrage n'a pas eu d'influence sur la maturation. On peut donc dire que si une croissance déficiente au nid peut être compensée plus tard, la piètre qualité du lait maternel peut avoir des conséquences de longue durée sur la maturation sexuelle des rejetons femelles. Dans la seconde expérience, les souris nourries de régimes isocaloriques contenant 14, 20 et 30% de protéines ont toutes eu le même taux de croissance, au nid et après la sortie du nid. Les différences obtenues à 42 jours quant au nombre de femelles à maturité ne correspondaient pas au contenu en protéines du régime alimentaire, contrairement aux prédictions. Un contenu en protéines de 14 à 30% semble suffire aux Souris sylvestres gardées en captivité.[Traduit par la Rédaction] McAdam and Millar 1828

Moulting patterns inClethrionomys gapperi

“…This was expected because dependent young that grow faster are likely in better condition than those growing more slowly (Koskela et al 1998, Lidicker andOstfeld 1991). In small mammals, the growth rate of pups before weaning is dependent upon the mother, and maternal effects can last until adulthood (McAdam and Millar 1999). In our study, variation in growth rates among litters was significantly greater than variation in growth within litters, indicating maternal effects on growth rates.…”

Does high growth rate of juvenile house mice with prolonged access to ripening grain and free water drive population outbreaks?

“…Somewhat similar hypotheses, for example on the link between pre-weaning protein deficiency and sexual maturation, have been experimentally tested on deer-mice (McAdam & Millar 1999). Whatever the underlying cause, variation in body mass of weanling house mice living in wheat crops is likely to affect their subsequent growth rates and timing of sexual maturation, and consequently, the rate of increase of the population.…”

Sexual size dimorphism in bighorn sheep (Ovis canadensis): effects of population density

“…Compensatory growth is a period of accelerated growth that follows a period of decreased growth due to food restriction or environmental perturbations, but it requires relaxation of the food restriction (Verme 1963;Hudson and White 1985). It has been reported for various species (McAdam and Millar 1999;Badyaev and Martin 2000), including domestic sheep (Oldham et al 1999) and wild ungulates (Toïgo et al 1999). Females may direct more resources to growth and fewer to reproduction when food is scarce.…”