CRV Ambreed has a major genetic breakthrough that will potentially provide a solution for more sustainable dairy farming in New Zealand.
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 Nitrogen excreted in urine is desirable to reduce this leaching.
CRV Ambreed has several research and development programmes aimed at improving farming sustainability using genetics.Breeding to reduce Nitrogen excreted in urine is one of those programmes.
The breakthrough occurred when CRV Ambreed researchers investigated the potential of reducing Milk Urea concentration through traditional genetic selection.
Research over five years (2012-2017) established that indeed it is possible to reduce Milk Urea concentration through genetics. Milk Urea Nitrogen is the Nitrogen component of Milk Urea, with Nitrogen making up 46% of Milk Urea. Therefore by reducing Milk Urea concentration we also reduce Milk Urea Nitrogen concentration.
International research has shown there is a direct relationship between Milk Urea Nitrogen concentration and the amount of Nitrogen excreted in urine. It follows that if we reduce Milk Urea Nitrogen concentration through breeding, we will reduce the amount of Nitrogen excreted in cow urine.
In 2017 we released our first team of bulls to reduce Milk Urea Nitrogen through genetics, the LowN Sires bull team.
The daughters of these sires will have a lower Milk Urea Nitrogen concentration in their milk compared to the daughters of the average bull. In turn, these daughters are confidently expected to excrete less Nitrogen in their urine and consequently less Nitrogen will be leached into groundwater.
LowN Sires are potentially a powerful aid assisting farmers to reduce their environmental footprint.
Research conducted over five seasons involved measuring Milk Urea Nitrogen concentration in hundreds of thousands of milk samples from individual cows through the CRV Ambreed herd testing service.
These Milk Urea Nitrogen concentration (MUN) values were then analysed by AgResearch and CRV geneticists to calculate MUN Breeding Values for the sires of the cows. Bulls with negative breeding values for MUN are expected to reduce MUN in their daughters and this is a favourable outcome. On the other hand, bulls with positive MUN breeding values are expected to breed daughters with increased MUN.
The LowN Sires bull team have lower breeding value for MUN compared to the average bull. Therefore, their daughters will have lower MUN.
Breeding with LowN Sires? will reduce Milk Urea Nitrogen concentration in their progeny.
International work shows that if Milk Urea Nitrogen is reduced, then the amount of Nitrogen excreted in Urine is reduced.
If the amount of Nitrogen excreted in urine is reduced, then the amount of Nitrogen leached into groundwater and waterways is reduced.
Progeny of the LowN Sires will be lower for Milk Urea Nitrogen compared to progeny of the average bull.
Using the relationships between Milk Urea Nitrogen and Nitrogen excreted in Urine found by international researchers, we expect, on average, that these low Milk Urea Nitrogen cows will excrete 3.2kg less Nitrogen per cow per year (ie a reduction in Urinary Nitrogen of 3.2kg per cow per year).
Modelling predicts that for average farm systems on silt loam soils, cows excreting 3.2kg less Nitrogen, will result in an 8-10% reduction in Nitrogen leached.
Farmers are urged to seriously consider using LowN Sires now in order to begin reducing Milk Urea Nitrogen through genetics. These genetic gains will be in addition to gains made through changes in farm management.
An extensive research program to further investigate the implications of breeding for low Milk Urea Nitrogen involving industry research groups is underway.
Low N Livestock is a DairyNZ-led collaborative research programme delivering science for better farming and environmental outcomes. The aim is to develop the knowledge and tools required to breed cows with urinary nitrogen excretion characteristics that reduce the risk of nitrogen leaching and to implement genetic and management strategies that reduce nitrogen losses to the environment. The main funders are DairyNZ and the Ministry of Business, Innovation and Employment, with co-funding from CRV-Ambreed and Fonterra.
When outcomes of this research are known, it is likely Milk Urea Nitrogen will be included in farm models such as farm nutrient modelling programs.
On our part, CRV Ambreed will continue breeding LowN Sires for the future: our predictions are that over 20 years it is possible to reduce Nitrogen leached from dairy by 20-25% through genetic selection.
One of the very encouraging findings of the CRV Ambreed research has been that the LowN Sires™ are generally very good for other important traits: so it appears we are not losing out on traits like longevity and milksolids.
The daughters of LowN Sires™ will milk as well and live as long as your ideal cow.
Farmers who herd test and record with CRV Ambreed will receive Milk Urea Nitrogen breeding values for their cows as a new piece of information. These farmers will then be able to identify those cows with high Milk Urea Nitrogen BV's and decide whether they wish to either cull the cow or not retain its progeny.