5 Takeaways from the 2022 NZVA Conference for Dairy Farmers

In June some of our vets attended the 2022 NZVA Conference in Hamilton - Dairy Cattle Veterinarians stream. After an amazing few days, with some incredible speakers our vet Bianca has put together some of her key learnings that really captured her attention from the conference.

Preserving colostrum

E. coli levels in colostrum can reach VERY high levels by 7 days post collection if no preservative is used. This affects the ability of the calf to absorb the antibodies in the colostrum and can contribute to a higher incidence of failure of passive transfer (FPT). Potassium sorbate is the best choice of preservative for colostrum (when measuring bacterial counts, pH and Brix %). BUT any preservative is better than nothing. Other preservatives that were tested were citric acid and yoghurt, both performed adequately.

Take-home messages:
  • Hygiene matters!!! (when collecting and storing colostrum)
  • Preserving - ABSOLUTELY
  • With what? Potassium sorbate is best

Salmonella vaccination and transfer of antibody to calves

A trial was done to see if the timing of Salmonella vaccination affected the amount of Salmonella antibodies available to the calf via colostrum. There were three groups in the trial, one group was left unvaccinated, one group was vaccinated at drying off, and one group was vaccinated 4 weeks prior to calving. The calves from both of the vaccinated groups had significantly higher Salmonella Typhimurium antibodies than the unvaccinated group. There was no difference in antibody levels between the two vaccinated groups, which gives flexibility to farmers in the timing of their Salmonella vaccination programme. Interestingly, during the study, three different types of Salmonella were circulating in this herd, despite no previous history of vaccination or disease.

Pillars of a new dairy system - High vs Low fertility BV

As part of the ‘Pillars of a new dairy system’ project, a research herd of 550 heifers with positive (+5%) and negative (-5%) BVs for fertility was put together. The aim was to compare the two groups to help identify new fertility traits and improve the accuracy of calculating the fertility BV. Researchers collected samples and data from the animals throughout heifer rearing, 1st and 2nd lactations (for reference the national average BV for fertility is +0.2%).

There were some astounding differences between the two groups:
  • Positive BV heifers were younger and lighter at puberty and were a lower % of mature live weight compared to the negative heifers when they reached puberty. The positive heifers also conceived earlier.
  • 6 week in-calf rates were approx 30% higher in the positive group compared with the negative group.
  • There was a 10% difference in final in-calf rates in the 1st lactation and a 14% difference in the 2nd lactation.
  • Submission rates in the positive group were 38% higher in the 1st lactation and 25% higher in the 2nd lactation.
  • The positive heifers had stronger and longer heats
  • By the end of the second lactation, there were only 27% of the negative heifers remaining in the herd, compared with 64% of the positive heifers!
The differences found in this study will help to develop new traits to improve the Fertility BV.
Using bulls with positive BVs for fertility will help to improve herd fertility.

Johnes disease - yesterday, today and tomorrow, an LIC perspective

It is estimated that 60% of NZ dairy herds have Johnes. The average incidence in South Island herds is 3.5% which is higher than the national average of 3.1%. More than a quarter of the total dairy animals in the South Island were tested by LIC milk antibody tests in the 2020/21 season. Testing across several seasons appears to be having an impact on the overall antibody-positive prevalence within herds. There are limitations to Johne’s disease testing due to the inability to detect animals early in the infection cycle and studies are underway to develop new testing methods that will help identify animals earlier.

Cow monitoring technology

‘Cow wearables’ are becoming increasingly common both across NZ and in our local area. At the moment the most common use of the information on farms is for health and heat detection. There is a wealth of information that can be gained from this technology and there are some very exciting opportunities to use this ‘real-time’ data to help identify areas for intervention to prevent disease and improve productivity.

An example of this is some early work showing the effect of once-daily milking after calving on rumination rate recovery, and the subsequent effect on in-calf rates. Cows milked twice daily after calving showed lower rumination rates in the first 30 days after calving, slower rumination rate recovery after calving, and had significantly poorer in-calf rates than those milked once daily. Some farmers are now using rumination rates to indicate when a cow is ‘ready’ to go from once-a-day milking to twice-daily milking after calving. This technology and the understanding of what is ‘normal’ is still in its infancy. There are some very exciting opportunities in this space!  

- Bianca MacKintosh


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