Milk composition, milk consumption, and growth rate of a captive spotted seal (Phoca largha) pup from Liaodong Bay, China

Abstract

As lactation is commonly very brief in phocid seals, the transfer of sufficient energy between mother and offspring is critical for their reproductive success. In this study, we investigated variation in the pattern of energy transfer and allocation during lactation in the spotted seal (Phoca largha Pallas, 1811). Temporal changes in milk composition, milk consumption, and pup mass gain were analyzed from birth to weaning in a spotted seal pup that was hand-reared on a donor-female’s milk. In addition, growth rates were measured in six pups raised in captivity but nursed naturally. We found that milk fat content increased and water content decreased during lactation. We calculated that spotted seal pup ingest a mean (±SD) daily energy of 39.5 ± 8.6 MJ/day, which corresponded to a daily mass gain of 0.9 kg/day. We found that the growth rates of the hand-reared pup and the six naturally reared pups did not differ, and overall, the mean (±SD) daily growth rate of spotted seal pups was 1.1 ± 0.2 kg/day before weaning and 0.6 ± 0.2 kg/day from birth to molt. Our study provides the first data on lactation patterns in this species.