title: Monitoring of vitamin E status of dry, early and mid-late lactating organic dairy cows fed conserved roughages during the indoor period and factors influencing forage vitamin E levels.
abstract: Analysis of blood plasma of 60 cows selected on six Flemish organic dairy farms revealed that on average 12% of all samples and on one farm up to 28% of the organic cows showed plasma vitamin E concentrations less than 3.0 μg/ml, which is considered the minimum level to avoid health risks due to vitamin E shortages. Furthermore, this study showed early lactating and dry cows to be more at risk in relation to animals in mid-late lactation. In European organic farming, vitamin supplements are only allowed if granted by the local authority to satisfy daily requirements. Therefore, the vitamin E content of the feedstuffs used on the farms was determined. Grass clover silage (GCS) and mixed silage had significantly more vitamin E than hay, maize or grain (p < 0.05) [mean (SD): 52 (35), 29 (20), 4.5 (1.7), 4.9 (4.4) and 7.1 (3.8) mg/kg DM, respectively]. Apparently, variation in the vitamin E content in the silage samples was huge. Hence, the vitamin E content of ryegrass, white and red clover was determined in a second lab scale experiment and the effects of wilting, DM content and supplementation of ensiling additives were investigated. Fresh ryegrass had a higher vitamin E content than white and red clover (p < 0.05) [156 (11.3), 49.3 (0.67) and 74.3 (5.73) μg/g DM, respectively]. These differences remained after the wilting or ensiling. Supplementation of formic acid or lactic acid bacteria at ensiling had no significant effect on the vitamin E content. Overall, it can be concluded that GCS is the most important source of vitamin E in organic dairy farming. A legal possibility for case-related supplementation should be retained in organic dairy farming as approximately 18% of all dry and early lactating cows were at risk of vitamin E shortage.
authors.affiliation: Laboratory of Animal Nutrition and Animal Product Quality, Ghent University, Melle, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Beeckman
authors.forename: J
authors.initials: J
authors.lastname: Vicca
authors.forename: G
authors.initials: G
authors.lastname: Van Ranst
authors.forename: G P J
authors.initials: GP
authors.lastname: Janssens
authors.forename: V
authors.initials: V
authors.lastname: Fievez
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D003612:Dairying / Q000379:methods; D004032:Diet / Q000662:veterinary; D005260:Female; D007774:Lactation / Q000502:physiology*; D012434:Secale; D029921:Trifolium; D024502:alpha-Tocopherol / Q000097:blood* / Q000737:chemistry*
chemical_list: D024502:alpha-Tocopherol