Tackling drops in Freezing Point Depression

Published 24 July 18

Dairy farmers have raised concerns recently over decreases in the Freezing Point Depression (FPD) of milk and potential penalties.  

This article answers frequently asked questioned and outlines top tips to help you to identify the cause of low FPD and effectively tackle the situation. A low FPD, when not caused by water contamination, is generally caused by a combination of different issues.

 Useful Info FPD 1

My milk regularly shows a decrease in FPD in Spring, is this normal?

Seasonality does have an effect on FPD, with lower values reported during spring and summer time. The reason for this is both nutrition and climate-related:  water intake in these seasons is higher, due to higher temperatures and turn-out at pasture with increasing intakes of fresh grass.


This summer my FPD is very low, what is happening?

This summer is being particularly harsh on agriculture, with exceptionally high temperatures and water scarcity. Water requirements of dairy cows under heat stress are significantly higher, especially if they are kept outside. If there are not enough working water troughs in the field and cows are fed dry feed instead of grass, or if grass has a high dry matter content, they will inevitably become very thirsty and binge on water as soon as they find an available source. If this occurs close to milking time, it can lead to rapid absorption of water through the rumen, into the blood and finally into the milk. Additionally, this effect can be made worse through lack of proper mineral intake; heat-stressed cows lose potassium and sodium when they sweat. 


What is the role of nutrition in altering FPD?

The nutritional effects on FPD are not consistent. Due to imbalances in energy and protein cows that consume low levels of dietary protein, (i.e low energy), can decrease FPD, as milk samples with low urea and protein have shown to have a lower FPD. Find out more here.


Are fresh cows more likely to have a low FPD in milk?

As previously mentioned, this study reported an effect of lactation stage (Days in milk), with FPD levels closer to 0 during the first 3 months. This finding in particularly important for block calvers, especially spring block calvers, who may suffer from the effects on FPD of both lactation phase and seasonality. 


Is there a breed effect?

Different breeds can have slightly different FPDs, probably due to the solid contents, but the difference is of no practical relevance when large changes in FPD are reported.


TOP TIPS for FPD at critical levels

  • Do not rule out water contamination of milk. Any addition of water to milk will cause dilution and decrease FPD. Thoroughly check the milking plant, including cooling and storage, to identify failures that could allow water to get into the milk
  • Make sure cows have access to fresh/clean water at all times, both inside and in the field, particularly during hot weather.
  • Make sure that water troughs in the field are working. Fix any leaks and check that the pressure allows for a prompt refilling of troughs, especially when several animals are drinking at the same time
  • It is not acceptable to  restrict water intakes
  • Protect cows from heat stress: this involves providing shade (or even housing them during the day in the hottest periods if feasible) and cooling down by means of fans, sprinklers or evaporative cooling
  • Discuss with your nutritionist the opportunity to add minerals (salt) and/or to review the diet if milk components and urea suggest so

 For further information please contact martina.dorigo@ahdb.org.uk

We are thankful for the inputs received by partners, including The Dairy Group, Arla Foods, NMR and Dairy UK, in preparing this guidance