871
MILK AND BLOOD SELENIUM CONCENTRATIONS IN DAIRY CATTLE DIFFER DEPENDING ON THE SOURCE OF SELENIUM SUPPLEMENTATION (SODIUM SELENITE, SELENIUM-YEAST OR L-SELENOMETHIONINE)
Adequate Selenium (Se) levels are beneficial for dairy cattle health and fertility. Since many regions in the world have soils with low Se content, supplementation of this trace element is very often warranted. The aim of the present study was to evaluate three different Se sources: sodium selenite (NaSe), selenium-yeast (SeYeast) and L-selenomethionine (SeMet) in their potential to achieve adequate blood and milk Se levels.
A feeding trial was set-up with 26 high producing Holstein Friesian cows. After a two week pre-treatment period without Se supplementation, cows divided in four homogenous groups receiving either no supplementation (Ctrl) or 0.3mg per kg dry matter (DM) of either NaSe, SeYeast or SeMet for the next 7 weeks. Cows were given maize and prewilted grass silage ad libitum, a protein source and a balanced concentrate. Milk and blood serum samples were taken during the pre-treatment period (week 0) and at week 3 and 7 after the start of supplementation. Blood serum Se concentrations were analysed by atomic absorption spectrometry. Milk Se concentration was determined by inductively coupled plasma mass spectrometry. Data within each week have been analyzed using ANOVA with treatment as fixed effect.
Table 1. Blood and milk Se in Ctrl, NaSe, SeYeast and SeMet at week 0, 3 and 7.
|
Week |
Ctrl |
NaSe |
SeYeast |
SeMet |
Blood Se (µg/L) |
0 |
34±10 |
25± 4 |
35±13 |
31±10 |
3 |
39±12a |
63±14b |
71±13b |
68±11b |
|
7 |
23±5a |
57±12b |
71±13c |
69±10c |
|
Milk Se (µg/kg) |
0 |
16±2 |
15±1 |
14±2 |
16±2 |
3 |
18±3a |
26±2b |
45±6c |
61±4d |
|
7 |
21±9a |
46±15b |
63±12c |
75±14c |
abcdValues with different superscript differ significantly between groups within the same week (row)
DMI was constant during the trial. Milk production was 29.9kg in Ctrl, 31.6kg in NaSe, 28.3kg in SeYeast and 27.8kg in SeMet cows. Milk composition showed small differences between treatments. The mean blood serum Se and milk Se concentrations during the pre-treatment period were not different between groups (Table 1). The increase in milk Se concentration between week 0 and week 3 was significantly more pronounced for SeMet in comparison with SeYeast and NaSe which indicates a better transfer from feed to milk after SeMet supplementation. After 7 weeks supplementation Se levels in blood and milk were equally high for SeYeast and SeMet and lower for Ctrl and NaSe.
Increase in milk Se content after supplementation is clearly affected by type of Se source.
Keywords: Dairy - Selenium - Transfer