The incidence of calves being still born can be frustrating for farmers as well as an economic loss. In my time of consulting I have have been asked many times about the issue. Many years ago I had a call from a Queensland (Australia)dairy farmer, he said “ All my cows are having dead calves what’s the problem?” My question to him was “Are they grazing fresh lucerne?” to which he replied they are. A quick change of diet away from the fresh lucerne and from then all calves were born alive.

Another call from a fellow associate saying that a NZ northland dairy farmer had 6 still births from his first 10 cows to calf. So why?

Still births are normally associated with a high intake of nitrates usually when grazing fresh growthy lucerne/pasture or pasture that has recently had urea applied, this can occur in all animals, cattle, dairy, sheep, horses. There was a case many years ago where I observed an in foal mare grazing fresh growthy rye grass, I suggested that the owner change her diet as it was likely her foal would be born dead, the advice fell on deaf ears, the foal was still born.

Western Australian research with sheep showed a significant increase in live lamb percentage when corn was fed during the last 10 days prior to giving birth

On NZ dairy farms it often occurs with the later calvers – mainly due to a change in grazing – later calvers are often grazing spring regrowth pastures which are very high in nitrates

Pasture nitrates are the main cause, here’s why -

[a] Slow growing winter or summer pasture normally contain high quality protein

[b]  Plants take up nitrogen from the soil as nitrate N, this nitrate N is converted to amino acids or high quality protein. But when growth rates increase and animals are grazing faster growing pastures they are now consuming higher rates of protein and a high percentage of the protein is still in the form of nitrate nitrogen. Some pasture species, depending on the soils nutrient status, weather conditions and growth rates nitrogen stay’s in the nitrate form for a longer period, so instead of ingesting high quality protein the animal is ingesting a percentage of junk protein (nitrate protein).

Its also important to understand that protein is a calculation = total plant nitrogen X 6.25, total nitrogen includes all the various forms of N in a plant

[c] Nitrate N is converted by rumen organisms to ammonia N and is transferred to the blood

[d] High blood N results in inflammation of the cotyledons (The connectors between uterus and the placenta)

[e] Once inflamed oxygen to the foetus becomes restricted and so if completely restricted the foetus dies and is still boron

Other side effects can be

• Weak calves at birth
• Increased scours in calves
• Calf deaths at 7 to 10days old
• Respiratory issues in the new calf

Prevention:

1. Recognise the stage of growth of the pasture/lucerne that is being grazed
2. Avoid grazing any type of pasture that is in a fresh growth stage
3. Minimise pasture and increase pasture hay/maize silage intake in the last 10 days prior to calving – Many older farmers fed only hay and minimum pasture during this period. Lucerne hay should be avoided
4. Feed a good mineral supplement
5. Inject stock with Vitamin ADE 10 days before calving starts