Influence of high‐altitude grazing on bone metabolism of growing sheep

Abstract

The objective of this study was to identify the effect of high alpine grazing, associated with varying pasture grass qualities and more pronounced exercise on typically steep slopes, on bone metabolism by improving bone density and enhancing bone turnover in growing sheep. Twenty-four 5-month-old sheep were randomly assigned to two groups. One group was kept at high altitude (HA; 2000-2200 m a.s.l.) for 3 months, and the other group (C; control) remained in the lowlands (400 m a.s.l.). Both groups were kept in grazing pastures with access to good-quality swards. Before the start of the experiment, blood samples were taken, the sheep were weighed, and the left metatarsus of each animal was analysed by quantitative computer tomography. After 1 month, blood samples were taken and body weight was measured, followed by biweekly sampling. Finally, the animals were slaughtered, and the bones were collected for analysis of various bone parameters. Body weight development did not differ between the groups. Concentrations of 25-OH-Vitamin D, carboxy-terminal telopeptide of type I collagen and activities of bone-specific alkaline phosphatase were always higher in the HA group than in the C group, except on the last two sampling dates. Bone mineral content and density increased in both groups during the experiment, but more intensively in the HA group. In addition, the cortical thickness of the HA group increased. The present study demonstrates an increase in bone turnover and mineral content of the bones of the growing sheep grazing in high alpine pastures. The factors associated with HA grazing, therefore, clearly seem to improve bone composition.

Influence ofUVBexposure on the vitamin D status and calcium homoeostasis of growing sheep and goats

“…The time patterns of parameters related to BMD are in accordance with former results obtained in growing sheep in the studies of Liesegang et al. (, ) thus indicating a normal physiological process of ageing. Significant species differences in BMD between the two species were found in week 12 where lambs showed higher BMD levels compared to goat kids.…”

Bone turnover markers in sheep and goat: A review of the scientific literature

“…MacLeay et al (2004a) concluded that during the administration of a diet that induced metabolic acidosis in mature ewes, there were no significant changes in serum BALP and DPD levels. In another study by Liesegang et al (2013) with sheep grazing at different altitudes, it was not possible to confirm the interference of diet in the serum variation of ICTP or BALP, but high bone turnover was confirmed. Also, in a study by Liesegang and Risteli (2005) where a diet with varying calcium content was used, it was not possible to demonstrate the influence of the diet on bone mineral metabolism in growing goats and sheep, possibly due to the short duration of this study, where only the sheep showed a variation in BMD due to an increase in calcium intake.…”

“…Biological variability can be influenced by many uncontrollable factors (Cremers et al 2008), such as growth (Sousa et al 2014a), geographical location (Liesegang et al 2013), pregnancy and lactation (Liesegang et al 2006, Liesegang et al 2007, and controllable factors, such as diet (MacLeay et al 2004a, b, Liesegang et al 2013, and season of the year (Arens et al 2007), which can be mitigated in clinical studies (Liesegang 2008). In short, biological variability is affected by any factor that influences the bone remodelling (Watts 1999).…”

“…Nevertheless, the reported biological variability of BTMs among age, gender, disease, recent fractures, exercise, time (Seibel 2005), diet (Nicodemo et al 1999, Liesegang and Risteli 2005, Liesegang et al 2013, seasonal changes (Arens et al 2007) and circadian variation (Liesegang et al 2003), which can contribute substantially to the variability of these parameters (Smith et al 2011), are their main limitation (Cremers et al 2008).…”

Performance of confined and grazing lambs fed diets with different mineral-concentrate supplements

“…The reverse also occurs if there is an excess supply or energy needs are low (Hugejiletu et al, 2013;Liesegang et al, 2013). During experiments I and II, the consumption of mineral salts by the animals was within the recommended range, and thus no decrease in weight gain occurred.…”