Summary Of Herd Blood Testing For Effectiveness Of Mag-mix 50%
Introduction
Summary of serial blood testing for effectiveness of Mag Mix 50% to raise the blood magnesium levels and thereby treat or prevent hypomagnesaemia in the herd. The testing took place on the property of Mr D Campbell, at Muir Road, Te Awamutu, milking 270 Jersey cows.
Background
Since servicing the above property for four years the only forms of mineral supplementation has been via a Dosatron in-line dispenser. Early spring blood tests were carried out following a period of peri-calving dusting with magnesium oxide followed by supplementation with magnesium chloride at a rate of 100 gms/cow/day for four weeks before testing.
Situation
Routine blood tests revealed what would be classified as significantly low levels in a proportion of the cows sampled (see results and graphs). Following discussions with the farm's new season sharemilker it was decided to discontinue water treatments with magnesium chloride and initiate a magnesium oxide drenching programme on October 16, 1999. It was decided to use the Vetapk product Mag Mix 50 for the following reasons:
- Only a manual drench gun and back pack were available.
- A known dose of magnesium in a small well suspended volume able to go through the manual drench gun.
- The cost was equivalent to that already being spent on water treatment which was ineffective.
Serial blood testing of the same sentinel cows was carried out at regular intervals to follow progress.
Dose Rate
The standard dose rate (45mls) was to be used throughout the period of supplementation but this did not occur. At some stage during the second 200 litre drum there was a malfunction with the drench gun as the drum lasted longer than it should have. The dose rate during this period was calculated to be 31mls. To compensate for this it was decided to increase the dose rate from the next drum to 55 mls (+20%).
| Date Range of Dose Rates |
Dose of Mag Mix 50 mls / cow / day |
| 16/10/99 - 4/11/99 | 45 |
| 5/11/99 - 28/11/99 | 31 |
| 29/11/99 - 12/12/99 | 55 |
Results
| Average blood magnesium level (mmol/l) | No. of cows below ref. range (i.e. low) |
|
| 1/10/99 |
70 | 4 |
| 4/11/99 | 77 | 2 |
| 1/12/99 | 81 | 3 |
| 11/12/99 | 88 | 1 |
Conclusions
In summary Mag Mix 50 was effective at increasing blood magnesium levels in this group of cows and it is assumed would be very effective treatment and prevention of hypomagnesaemia
Greg McNeil, BVSc
