Low N Sires®



LowN sires pathway


LowN Sires® > reduce Milk Urea Nitogren (MUN)  through breeding.

LowN Sires® is potentially a powerful aid assisting farmers to reduce their environmental footprint. The LowN Sires® team have a lower breeding value for Milk Urea Nitrogen, compared to the average bull.

Agriculture’s impact on the environment is a major topic world-wide. In New Zealand degradation of waterways is the main concern.

Much of the contamination of waterways is caused by Nitrogen leached from urine patches of cows. Reduction of the concentration of Nitrogen excreted in urine is desirable to reduce this leaching.

CRV has several research and development programmes, both in New Zealand and internationally, aimed at improving farming sustainability.

Investigation into whether breeding can reduce Nitrogen concentration in urine is one of those programmes.



To discuss further or to order LowN Sires®, contact the CRV field consultants


MUN is the concentration of Urea Nitrogen contained in milk.

The daughters of LowN Sires will have lower MUN than the daughters of the average bull

Three steps to understand the pathway:
1. Breeding with LowN Sires™ will reduce MUN concentration in their progeny.
2. International research shows if MUN is reduced, then the amount of Nitrogen excreted in Urine is reduced.
3. If the amount of Nitrogen excreted in urine is reduced then the amount of Nitrogen leached will be reduced.

Nitrogen leaching on dairy farms is a problem that predominantly stems from the cow’s urine.
• The amount of Nitrogen in the urine patch is the problem
• If we reduce the amount of Nitrogen hitting the ground by breeding cows that pee less nitrogen, then leaching will be reduced.

Dairy cattle convert nitrogen consumed into five areas: milk (protein + urea); growth (muscle); dung; gases; and urine. Modelling and genetic analysis of the LowN Sires™ bulls suggests about 25% of the nitrogen that will be diverted away from urine in their daughters will go into milk protein. Higher percentages of milk protein is good news for milk processing companies desiring less water in the drying process.

Compliance is a big topic for dairy farmers. Each region manages its waterways differently, and has different requirements for farmers.
• LowN Sires gives farmers a genetic tool in their toolbox to potentially achieve profitable sustainable dairying.
• These farmers are already working hard to protect the environment, and this gives them a genetic tool to be used alongside other initiatives.
• Gains made through genetics will be in addition to gains made from other initiatives

Breeding versus feeding cows are different avenues in terms of reducing nitrogen excreted as urine, but the two are expected to be additive, so the genetic gains by using LowN Sires bulls will add to gains from better feeding.

DairyNZ is leading a seven-year research programme that aims to breed cattle with a lower nitrate leaching footprint.

This programme will help farmers meet environmental targets by:

  • Identifying dairy cows with urinary N excretion characteristics that reduce the risk of nitrate leaching
  • Determining the genetic basis of those characteristics and the scope for selecting sires that produce ‘low N’ daughters and
  • Developing the breeding and management strategies required to implement ‘low N’ cows in farm systems
  • CRV Ambreed is working with DairyNZ, AgResearch and Fonterra on this.
  • Phase 2 of the research into where the nitrogen goes will study groups of animals genetically different for MUN to understand more precisely the relationship between reducing MUN and reducing nitrogen in urine.
  • Read more about the DairyNZ led research
Farmers who herd test and herd record with CRV Ambreed will have access to herd and individual cow MUN breeding values through InSight. Reports on herds as a whole will help ensure farmers are on track with their breeding direction if they have chosen a lower nitrogen approach. Results are also provided for individual cows so farmers can calculate what might be achieved by using high-performing bulls from the LowN Sires® team.

We’d love to talk. Contact your local field consultant to discuss how LowN Sires® will work for you.