Milk urea nitrogen and blood urea nitrogen are both becoming recognised issues in both our dairy industry and in human health. As higher nitrogen pasture is consumed then levels increase and the question is what is if any the adverse effect on milk quality. We know that there are serious side effects for health both in animals and humans as high blood levels can indicate live and kidney failure.

In livestock we see as a result of excess protein intake

1] Weight loss and scouring

2] Lower milk production unless high carb supplements are fed

3] Increased milk fever (low calcium) and grass staggers (low magnesium), increased acidosis (low sugar)

4] Full term calves born dead due to high blood urea resulting in increased in reduced oxygen to the foetus

5] Foot scald (lameness)

6] Increased mis-mothering in sheep and in severe cases in cattle

7] Poorer conception

8] Lower trace element mineral levels

9] Interference with thyroid function

10 Low vitamin A levels

Foot scald as a result of high protein pasture

In humans we see as a result of excess protein intake

1] Weight loss

2] Interference with thyroid function

3] Increased mental stability

4] Maybe the same as the following in humans – In livestock -Full term calves born dead due to high blood urea resulting in increased in reduced oxygen to the foetus

5] Increased blood pressure

6] Increased blood flow to the hands and feet

7] Lower magnesium

The challenge for the dairy industry is

1] What are the side effects of high applications of urea?

2] Research clearly shows the association between high N and MUN and BUN

3] What is any are the side affects on milk quality. High urea milk wouldn’t be good for our babies, noting that milk naturally contains some urea as part of its protein content

Sulphur: One significant change I saw at the recent Mystery Creek Field Days was that a much higher level of sulphur was now being recommended in fertiliser programs. This is both for winter, spring and autumn programs including nitrogen applications.

Sulphur is critical in that it helps the plant and the animal utilise nitrogen and helps to reduce the accumulation of nitrates. These new high sulphur programs need to be accepted by farmers as I would expect to see a reduction in both blood and milk urea levels. I must say my group have been recommending high sulphur for the past 30 years as some others have, but the important thing is not the past but the future.

Sulphur can be over supplied in your fertiliser as excess will suppress animal selenium, this can occur when high rates of gypsum are applied.

A lamb with severe selenium deficiency following gypsum application

I have attached an article by Dr Doo-Hong Min below. There are many others to be found on the net. Just search MUN or BUN