Hamel Sandra, Côté Steeve D
Département de Biologie and Centre d'études nordiques, Université Laval, 1045 avenue de la Médecine, Quebec, Canada.
Oecologia. 2009 Aug;161(2):421-32. doi: 10.1007/s00442-009-1377-y. Epub 2009 Jun 2.
The high energetic costs of lactation can lead to fundamental trade-offs in life-history traits, particularly in young females that reproduce before completing body growth. We assessed whether lactating female mountain goats (Oreamnos americanus) used behavioural tactics at fine spatio-temporal scales to increase energy intake to compensate for the costs of lactation. Lactating females increased bite rate and chewing rate compared with non-lactating females, but selected similar foraging sites in terms of plant quality and abundance. At peak lactation, forage intake of lactating females was >40% greater than that of non-lactating females. For females that had reached asymptotic body mass (i.e. > or =6 years old), summer mass gain of lactating females was similar to that of non-lactating females. At 4 and 5 years of age, however, daily mass gain of lactating females was about 20% lower than that of non-lactating females. We conclude that increased foraging may allow fully-grown lactating females to compensate for the energetic costs of lactation, but that there is a major trade-off between mass gain and lactation for younger females.
哺乳所需的高能量成本可能导致生命史特征的根本权衡，尤其是在身体生长尚未完成就开始繁殖的年轻雌性个体中。我们评估了哺乳期的雌性北美野山羊（Oreamnos americanus）是否在精细的时空尺度上运用行为策略来增加能量摄入，以补偿哺乳成本。与非哺乳期雌性相比，哺乳期雌性的啃咬率和咀嚼率有所提高，但在植物质量和丰富度方面选择了相似的觅食地点。在泌乳高峰期，哺乳期雌性的采食量比非哺乳期雌性高出40%以上。对于已达到渐近体重的雌性（即6岁及以上），哺乳期雌性的夏季体重增加与非哺乳期雌性相似。然而，在4岁和5岁时，哺乳期雌性的日体重增加比非哺乳期雌性低约20%。我们得出结论，增加觅食可能使成年哺乳期雌性能够补偿哺乳的能量成本，但对于较年轻的雌性来说，体重增加和哺乳之间存在重大权衡。
