Are there any differences in bone metabolism of lactating sheep and goats kept on high altitude and lowland pastures

Abstract

The purpose of this study was to investigate the impact of increased movement on different landscapes of lactating ewes and goats on bone metabolism.
A group of five adult lactating ewes and goats was kept on pasture at 2000 to 2600 m a.s.l. and 400 m a.s.l., respectively. Two ewes and goats were equipped with a GPS receiver in order to calculate daily tracks on the alpine landscape. The milk yield was measured, blood samples were taken and the metatarsus was measured three times with peripheral computed tomography (pQCT).
The ewes walked on average longer distances and covered larger altitude differences. They remained mainly on grass-covered landscapes, whereas the goats stayed in bush-dominated areas. The sheep from both groups revealed an increase in cortical thickness, bone mineral density (BMD) and bone mineral content (BMC). The goats from the lowland group revealed a decrease in BMD, whereas in the goats from the alpine group a decrease in cortical thickness and an increase in BMC was detectable. The goats produced significantly more milk than the sheep. In sheep, there was no lactation induced bone loss detectable compared to the goats which could be partially reduced by increased movement straights.