Influence of dietary supplementation on serum vitamin A and D concentrations and their seasonal variation in horses

Markku Saastamoinen,Johanna Juusela

doi:10.23986/afsci.72460

Markku Saastamoinen, Johanna Juusela

Open Access

https://doi.org/10.23986/afsci.72460

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Abstract

An experiment involving 40 adult trotters and saddle horses was conducted during a period of one year in order to investigate the influence of vitamin A (retinol) and D (25-(OH)D) supplementation on serum vitamin concentrations and the seasonal variation of the serum concentrations of these vitamins. Vitamin supplementation was started either at the beginning or in the middle of the indoor (winter) feeding period. Supplementation lasted from the beginning of September or January to the end of May. According to the results, neither the dietary vitamin supplementation nor the length of the grazing period had any consistent effect on the serum vitamin concentrations. Neither was there any systematic seasonal variation in the serum retinol and 25-hydroxyvitamin D levels.

Highlights

Fresh grass and hay are the most important sources of vitamin A for horses (e.g., Fonnesbeck and Symons 1967)
The synthesis of vitamin D 3 in the skin depends on season of the year, geographical latitude and intensity of sunlight (Nutrition Reviews 1989)
Neither was there any consistent seasonal variation in the serum vitamin concentrations; the concentrations did not rise during the summertime

Summary

Introduction

Fresh grass and hay are the most important sources of vitamin A (retinol) for horses (e.g., Fonnesbeck and Symons 1967). Vitamin D 3 is synthetized in the skin (Webb and Holick 1988). The synthesis of vitamin D 3 in the skin depends on season of the year, geographical latitude and intensity of sunlight (Nutrition Reviews 1989). During the winter season the supply of fat-soluble vitamins may be inadequate. The vitamin concentrations of the most common combination of feeds used in horse feeding often decrease due to a long storage time. The synthesis of vitamin D 3 in the skin during the wintertime is minor because of the short day and the small amount of sunshine

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