Supplementing dairy steers and organically managed dairy cows with synthetic vitamin D₃is unnecessary at pasture during exposure to summer sunlight

Abstract

Use of synthetic feed additives, including synthetic vitamin D3 (D3) in the feed for cows and other ruminants, is not consistent with the international principles of organic farming. If dairy farmers wish to produce in accordance with the organic principles, production animals would be left with only their endogenous production of D3 from summer sunlight as a source of D3. To examine the impact of supplemental synthetic D3 from the feed on the D3 status of dairy cattle in organic production in Nordic countries, 20 high-yielding dairy cows and 30 dairy steers were divided into two groups: one supplemented with synthetic D3 in the feed and one not supplemented with synthetic D3. Vitamin D3 status of the animals was assessed by measuring the concentration of the liver-derived 25-hydroxyvitamin D3 (25OHD3) in plasma. Results showed that 25OHD3 concentration in plasma from dairy cattle as well as from steers decreased during winter for both supplemented and unsupplemented groups. Unsupplemented cows and steers had approximately 2 ng 25OHD3 per ml plasma during winter, whereas supplemented animals had between 10 (cows) and 30 (steers) ng/ml. During summer and autumn there was no additive effect of supplementing with synthetic D3 since unsupplemented and supplemented animals had the same D3 status at this time of year. In all cows summer concentrations of 25OHD3 were 20-25 ng/ml and in all steers 40-50 ng/ml plasma. The decrease in vitamin D3 status during winter indicates that cows and steers are able to store D3 only to a limited extent. The results also show that cows or steers fed supplemental D3 according to Swedish recommendation throughout the year are not able to maintain their summer value of 25OHD3 during winter.

Influence of vitamins A, D3 and E status on post-mortem meat quality in steers under winter housing or pasture finishing systems

“…Although Daniel et al (2004) reported that vitamin A supplementation can stimulate D-9 desaturase activity, leading to higher proportions of C16:1c-9 and C18:1c-9, such effects would not be relevant to this trial because vitamin A content was not affected by vitamin supplementation in either the indoor or outdoor finishing programmes. The difference in plasma 25-OH D 3 between supplemented groups present at the start of the trial (Hymøller et al, 2009) remained at the indoor finishing period slaughter point. However, UV light exposure during the outdoor pasture finishing programme was sufficient to equalise the plasma 25-OH D 3 concentrations between outdoor vitamins A, D 3 and E supplemented and non-supplemented animals.…”

“…Animal feeding and housing Swedish Red breed steers from a previous vitamin trial (Hymøller et al, 2009) were divided into vitamin supplemented (n 5 12) and non-supplemented (n 5 15) groups while on pasture before the finishing period. This trial started at the beginning of November when the steers were moved indoors and began the finishing phase.…”

“…Plasma 25-OH D 3 Initial plasma samples were collected at the beginning of the indoor housing period previously reported by Hymøller et al (2009). Final plasma samples were collected on the day of slaughter and analysed at the Faculty of Agricultural Sciences (Aarhus University, Tjele, Denmark) according to Vitamin-mediated calpain activity and beef tenderness the procedure described by Hymøller et al (2009).…”

“…Final plasma samples were collected on the day of slaughter and analysed at the Faculty of Agricultural Sciences (Aarhus University, Tjele, Denmark) according to Vitamin-mediated calpain activity and beef tenderness 1143 the procedure described by Hymøller et al (2009). Briefly, 2 ml plasma was mixed with 150 ng internal standard, 1-a hydroxyvitamin D 3 (Fluka Chemie AG, Buschs, Switzerland).…”

“…Quantifications of retinol and a-tocopherol were done by comparison to an external standard (Calbiochem, La Jolla, CA, USA). Retinol and a-tocopherol were identified at an excitation wavelength of 290 nm and 344 nm, respectively, and with an emission wavelength of 327 nm and 472 nm, respectively.Plasma 25-OH D 3 Initial plasma samples were collected at the beginning of the indoor housing period previously reported by Hymøller et al (2009). Final plasma samples were collected on the day of slaughter and analysed at the Faculty of Agricultural Sciences (Aarhus University, Tjele, Denmark) according to Vitamin-mediated calpain activity and beef tenderness 1143 the procedure described by Hymøller et al (2009).…”