Litter gender composition affects maternal behavior of the primiparous mouse dam (Mus musculus).
Thirty-nine litters of the outbred Swiss CD-1 mouse strain were reduced at birth to 6 pups, according to three conditions: MM (all males), MF (3 males and 3 females), or FF (all females). The maternal behavior of their respective dams (frequency and duration of nursing, licking, nest-building, and other activities such as eating, drinking, sniffing, grooming, and undirected locomotor activity) were scored during a single 10-min session on Days 2, 3, 5, 7, 10, 14, and 18. Dams rearing MM litters showed higher scores of maternal care on Days 2 and 18 in the case of nursing, on Days 2, 7, and 10 in the case of nest-building, and on Day 18 in the case of licking. These results confirm previous rat data, which indicated that male and female pups are exposed early in infancy to a different pattern of maternal behavior. Concomitant measurements of pup development (body-weight gain and achievement of a number of physiological and neurobehavioral landmarks) indicated that these effects of litter gender composition are not mediated by gross changes in the maturational trends of the pups.
Alleva
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Section of Behavioural Pathophysiology, Istituto Superiore di Sanità, Rome, Italy.
Caprioli
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A
Laviola
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G
D000818:Animals; D005260:Female; D008098:Litter Size; D008297:Male; D008425:Maternal Behavior; D051379:Mice; D009425:Nesting Behavior; D012727:Sex Characteristics; D013391:Sucking Behavior