Lactation in llamas (Lama glama): estimating milk intake and output using stable isotope techniques

Abstract

Compared to many other domesticated ruminants, very little is known about lactation in South American camelids. However, knowledge about milk and milk nutrient intakes in suckling young is essential for giving recommendations on an adequate nutrient supply. Direct measurement of milk production in South American camelids is hardly applicable, due to their short teats of about 2 cm and the low storage capacity of the udder. Therefore, we estimated milk production in llamas by measuring the milk intake in suckling young as an indirect trait. The study was conducted in Germany under temperate climatic conditions involving 11 lactating dams at two consecutive lactation periods (average body mass: 147.7±18.2, mean ± SD). Milk intake was estimated from water kinetics of 17 suckling young using two different stable isotope techniques, namely the isotope dilution technique involving the application of deuterium oxide (D₂O) to the suckling young and the ’dose-to-the-mother’ technique involving the application of D₂O to the lactating dam. The latter method additionally allows for the estimation of non-milk water intakes of suckling young. Daily milk intakes averaged 2.7±0.63, 2.2±0.60 and 2.0 ± 0.51 kg at 3-4, 10-11 and 18-19 weeks postpartum. Milk intake in suckling young decreased with age when expressed as daily amount, percentage of body mass or per kg metabolic size (P < 0.001), but the influence of age was eliminated when expressed per g daily gain. In suckling llamas, total water turnover increased with age (P < 0.01), whereas the milk water fraction decreased (P < 0.001). With increasing age less water from milk and more water from other sources was ingested. In contrast, the fraction of the milk water excreted by the dam did not change, indicating a fairly constant relationship between milk-water excreted via milk and total water ingested during lactation. Our results show that the stable isotope techniques used in the present study give reasonable estimates of the milk production in llamas. Furthermore, combined with milk composition data, the present milk intake estimations at different stages of lactation can be used to establish recommendations for nutrient and energy requirements of suckling llamas and lactating dams.

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