Mineral Responses in Northland – Animal Health

Popular Summary

Summary

• Trace element research has a long history in Northland.
• MAF Agricultural Research Division ran almost 200 trials.
• Despite trial  sites  having  low  soil,  plant  or  blood  levels  of  some  trace elements,  there  have  been  remarkably  few  trace  element  responses  to supplementation.
• Copper  supplementation   is   proven   to   reduce   the   incidence   of   post parturient  haemoglobinuria  (PPH  or  redwater),  a  condition  seen  in  dairy cows shortly after calving.
• Trace element deficiencies are unlikely to be limiting livestock performance on Northland farms.

Copper and dairy cows

In a large survey of pasture, liver and blood levels of copper in more than 300 North Island herds, Northland cows were found to have the lowest blood copper levels. Those cows which had been supplemented (between 2 – 6 g/head/ day of copper sulphate for at least 2 months before collection) showed higher blood copper levels than those not supplemented. The work showed that pasture analysis has limited use for diagnosing deficiencies. Oral supplementation of copper sulphate will raise blood levels and maintain them within the normal range.

Serum copper levels:

Post-parturient haemoglobinuria (PPH)

PPH is characterised by anaemia, poor milk production and haemoglobinuria (blood in the urine) after calving. A trial showed supplementation with copper injections reduced incidence of PPH and helped reduce the fall in haemoglobin. Copper fertiliser has also proved to be an ef- fective method of reducing the incidence of PPH. The project involved farmers with a history of PPH giving half their herds copper injections (400mg copper glycinate – 120mg active copper) before calving and leaving the remainder untreated. The incidence of PPH-affected animals fell from 28.5% to 5.2% with the copper injections. Difficulties associated with copper injections prompted the use of copper sulphate or copper oxide as fertilisers to deliver 1.3kg/ha copper.

Effect of copper topdressing on the incidence of PPH

1  CuSO4 = Copper Sulphate, CuO = Copper Oxide
2  Production increase per farm over the months of Jul – Sept -adjusted for seasonal factors

 An extension of the project showed that an injection of copper (240 mg of available copper as copper glycinate) within 48 hours of calving:

• • Reduces the incidence of PPH
  • Maintains higher haemoglobin levels
  • Increases blood copper levels

Phosphorus supplementation

Phosphorus deficiency has only been recorded once in dairy cows in New Zealand. A survey of 200 cows across ten farms in Northland showed average serum Pi (inorganic phosphate) to be 1.3 mmol/l at peak lactation. The suggested normal range is 1.3 – 2.8 mmol/l. Animals with a level below 1.1 mmol/l may show clinical signs of P deficiency and may respond to phosphate supplementation. Given the low blood phosphate levels, a milk production response was considered possible. On a farm near Okaihau, 48 cows were divided into two groups and one group given 25g phosphate/head/day as sodium tripolyphosphate (TPP) and the control group received sodium chloride. After four weeks the blood response to TPP was small, so the control group were given dicalcium phosphate to compare phosphate availability. Serum phosphate, bodyweight, condition score and milk production were monitored through the trial.

Results:

• Liveweight did not vary between groups during the trial.
• Condition score showed a small, but significant (P<0.05) difference during the first and fourth period – Condition score in the cows receiving phosphate averaged 7, compared with 4.4 in the salt treated cows.
• Additional dietary calcium appeared to have no effect on availability of phosphate.
• Serum Pi levels were increased by supplementation.
• Despite the increase in serum Pi, there was no significant difference in milk production (milk, milk-fat or milk-protein) during the trial.
• The conclusion was that phosphate nutrition for most NZ dairy cattle should be adequate.

Copper supplementation:

Beef cattle

One trial on a volcanic soil near Kaikohe examined the live weight response to copper supplementation (by injection) in weaner Angus steers over 11 months. The results  indicated a decrease in growth rate with supplementation. Blood copper levels were  adequate.

Sheep

One trial involved 14 farms on two soil types (a heavy clay and a sand). Blood copper concentrations were all adequate. Copper supplementation had no effect on liveweight gain or blood copper concentrations.

Dairy cattle

A trial on two farms on sandy peat soils showed no response in milk production, condition score or reproductive performance to copper supplementation.

Cobalt supplementation:

Beef cattle

On three east coast properties and eight west coast properties, B12 in the blood was found to vary between sampling time and site. Only on one occasion did the concentration fall below adequate. No significant effect of supplementation was observed on blood B12 levels or liveweight.

Sheep

Similar results were found with sheep on 14 sites – eight on clay and six sandy soils. Only two sites had low serum B12 levels. Small positive liveweight gains occurred following supplementation on these two sites and one other site. On nine sites liveweight gains were slightly lower after supplementation.

Selenium supplementation

Beef cattle

A trial run on three farms situated on clay soils indicated no response to liveweight gains following selenium supplementation in the first year. A second trial on eight sandy soils on the West Coast indicated a small but statistically significant response. On one property  (Farm 5) the response was greater than on the other farms.

Effect of selenium supplementation on growth of beef cattle:

* Glutathione peroxidase activity (i.u./litre) collected in April before the trial as an indicator of selenium status

Sheep

A trial looked at selenium responses on eight farms on clay soils and six on sandy soils. There was no evidence of a selenium response. Selenium supplementation increased blood glutathione activity on most farms.

Effect of selenium supplementation on liveweight gain of sheep (Dec-Jun):

Dairy cows

The effect of selenium supplementation on dairy production was tested on two farms on sandy peat soils. There was no effect of selenium on milk production or on reproduction.

Conclusion

• Trace element deficiencies are unlikely to be limiting livestock performance on Northland farms.
• Supplementation needs to be discussed with animal health professionals.
• Trace elements nutrition is very complex:
  • There is low correlation between dietary copper and blood copper
  • Blood selenium is highly correlated with dietary selenium
  • Blood cobalt levels are influenced as much by grazing pressure as by supplementation
• Cobalt supplementation via injections and topdressing significantly increased serum levels in cattle, but has failed to produce a response.