Gastrointestinal transport of calcium and phosphate in lactating goats

• Published in: Livestock science 2016-07, Vol.189, p.23-31
• Main Authors: Starke, Svenja, Reimers, Julia, Muscher-Banse, Alexandra S., Schröder, Bernd, Breves, Gerhard, Wilkens, Mirja R.
• Format: Article
• Language: English
• Subjects: Calcium absorption; Macrominerals; Phosphate absorption; Rumen; Ruminants; Ussing chamber
• ISSN: 1871-1413; 1878-0490
• DOI: 10.1016/j.livsci.2016.04.023

Previous studies gave evidence for the assumption that in contrast to sheep, dairy goats can adapt to lactation-induced challenges of calcium (Ca) homeostasis by effective adaptation of gastrointestinal Ca absorption. Ca and phosphate (Pi) homeostasis are known to be closely related challenged during lactation. However, for both, Ca and Pi homeostasis, the underlying molecular mechanisms and their regulation during lactation in goats have only marginally been investigated so far. Therefore, the present study aimed to investigate the impact of lactation on gastrointestinal Ca and Pi absorption in dairy goats on a functional level using the Ussing chamber technique to determine macromineral fluxes across gastrointestinal epithelia, and on a structural level by analyzing gastrointestinal RNA and protein expression of key genes involved in transcellular Ca and Pi transport. Besides slightly increased functional Ca absorption and elevated expression of transient receptor potential vanilloid channel type 6, calbindin D9K and plasma membrane Ca2+-ATPase type 1 in jejunum, an upregulation of Ca absorption in lactating goats also occurred in the rumen in terms of increased Ca fluxes. However, the exact molecular and regulatory mechanisms have to be examined in more detail. Interestingly, intestinal Pi absorption in duodenum and jejunum was downregulated by lactation on functional level, and in accordance, sodium-dependent Picotransporter type IIb RNA and protein expression were decreased in jejunum. Whether this downregulation of intestinal Pi absorption can be attributed to sufficient Pi supply from endogenous sources or to lactation-induced increased dietary Pi intake has still to be investigated. •Striking adaptation of calcium absorption during lactation in goats was found.•Gastrointestinal calcium and phosphate transport during lactation was investigated.•Lactation enhanced ruminal and jejunal functional and structural calcium transport.•Lactation decreased jejunal phosphate transport on structural and functional level.