The NVI is the total merit index that is used in the Netherlands and Flanders for ranking bulls with the aim of putting those bulls at the top that are able to produce daughters that come closest to the national breeding goal. NVI is one of the best tools to help with that quest.
Using NVI in your breeding program will lead to:
- Improvement of production and longevity;
- Lower culling rates, which means fewer replacements and thus a higher income;
- More fertile and healthier cows, which will have a positive effect on income and consumer acceptance.
NVI is derived from a formula that takes into consideration three different components: production, health and conformation. Below the underlying traits are given en their contribution to the NVI.
In the table below the genetic gain (in breeding values) from selection with NVI after 1 generation is given.
|Feet & Legs||2.2||Pnt|
|Interval from first to last insemination||1.0||Pnt|
|Calving ease (paternal)||1.4||Pnt|
|Maternal calving process||1.1||Pnt|
Understanding Dutch type proofs
Understanding Dutch type proofs is not as difficult as you might think. The values and ranges of the Dutch proofs maybe look different from what you are used to, but if you compare them to US, Canadian and German proofs they are quite easy to understand. The graph shows the ranges of the proofs in the four different countries. For example, a bull with a breeding value of 108 on the Dutch scale is comparable with a US bull at +2.00 PTAT or a Canadian bull at +10 Conformation.
As you can see from the distribution of the indexes, 95% of the bulls have breeding values between 92 and 108. This means that bulls with a proof over 108 represent the top 2.5% of the breed.
This principle applies to any of the Dutch type traits, both the linears and the composites, and also to the Dutch proofs for management and health traits like udder health, and fertility.
CRV’s breeding program is not looking for extreme type in cows but for balanced and functional conformation. Cows need to have good locomotion and the ability to eat plenty of forage. Moreover, a well-balanced conformation will contribute to a healthy cow. According to CRV conformation is built up in frame, dairy strength, udder and feet & legs. The MRY breed is also scored on muscularity. In addition, udder and feet & legs are incorporated in the NVI. Using a sire with a breeding value of 112 for udder or feet & legs on a cow with a breeding value of 100 leads to an increase of 2.0 and 1.2 points on the classification scale, respectively.
NVI takes milk production into account by using the Inet index (Net Profit Index Milk Production). This index describes the net profit from one cow in its lifetime production. It is an estimated calculation in euros, where kg of fat, kg of protein and kg of lactose are taken into account. This amount of money is the total income of kg of fat, kg of protein and kg of lactose minus the feeding costs to produce this milk. These production costs are all based on the Dutch and Flemish situation.
High longevity means less culling, lower rearing costs and above all higher lifetime yields. The average score for longevity is 0 and is expressed in days. The standard deviation is 270 days.
- Bulls with a longevity breeding value > 0 have daughters with high longevity, staying longer in the herd
- Bulls with a longevity breeding value < 0 have daughters with below average longevity. On average cows are culled earlier.
Every point for longevity above 0 increases the average longevity of the bull’s daughters with 0.5 days. So if the bull of your choice has a longevity of 500 days, this means that his daughters will be on average 250 days longer in production.
This index is made up of all the traits that influence the birth of the calf and are influenced by the dam and the calf itself.
Costs that are accounted for are reduced production due to difficult calving, reduced fertility, early culling and veterinary costs. In particular, the potential loss of the calf is a significant cost item.
The traits corresponding to the birth index include:
- Calving ease (paternal)
- Maternal calving process (MCP)
- Vitality (paternal)
- Maternal vitality
Using a bull with a breeding value for calving ease and MCP of 104 on a cow with a breeding value of 100 will result in around 1.8% less difficult births in heifers and the combination of the same bull with the older cows will produce around 0.9% less difficult births. For breeding values under 100, the opposite applies: namely more difficult births, shorter gestation length and lower birth weight.
In addition, there is also a clear difference between heifers and higher parities regarding the paternal and maternal vitality. A sire with a breeding value of 104 for paternal (direct) vitality means that heifers will have around 3.2% more live-born calves from a bull and the combination of the same bull with older cows will give around 0.7% more live-born calves from the same bull. A sire with a breeding value of 104 for maternal vitality means that the female offspring of a bull will have 4.8% more live-born calves as heifers and 0.6% more live-born calves as older cows.