An explanation of the differences between American and Dutch breeding values

The counterparts of the total merit index NVI for farmers in the Netherlands and Flanders are the TPI and NM$ for their fellow dairy farmers in the United States. NM$ stands for Lifetime Net Merit. It is the official index for the US. NM$ is an economic breeding value that is a measure of the expected additional net profit that daughters of a bull will provide over their lifetime.

TPI stands for Total Performance Index and is provided by the US herdbook. Elsewhere in the world, TPI is often used to compare bulls.

‘Breeding on TPI leads to a different cow than breeding based on NVI’, says Jaap Brinkman, Global Product Manager Holstein at CRV. ‘For example, the TPI gives a relatively heavy weighting to production. Plus, the emphasis is more on kilograms of fat and protein than on the percentage of fat and protein.’

‘Health traits, on the other hand, are less important in the TPI formula than in the NVI’, he explains. ‘And within this segment the focus in the US is on daughter fertility. Breeding values for udder health, hoof health and milking speed are unknown in the United States’, according to Brinkman. And lastly, the conformation part of the TPI index is dominated by total type and udder; the emphasis for feet & legs in TPI is clearly lower than in NVI. Figure 1 shows the difference in structure between the TPI and NVI.

‘American breeding values are structured in a totally different way to the Dutch/Flemish values’, explains Brinkman. The breeding values of a bull are shown as PTA (Predicted Transmitting ability) while in the Netherlands and Flanders the actual transmitting ability of a bull is indicated. This also applies to the transmission of fat and protein percentages. Moreover, the base for components in the US differs quite a bit from the Dutch average. The plusses and minuses for components are displayed against the realised averages which at around 3.70% fat and 3.20% protein are much lower than in the Netherlands.

Another difference is how the transmission of conformation traits is shown. ‘For this category, the Americans use indexes with an average of zero and a spread of one point. In the Dutch/Flemish estimated breeding value, an average of one hundred and a spread of four points is applied’, Brinkman clarifies. ‘So this means, for example, that +1 on a US basis is similar to 104 on an NVI basis. And -1.5 in the United States equals 94 in the Netherlands and Flanders.’ Table 1 compares the American and Dutch/Flemish conformation scores.

In the international semen market NM$ is more and more accepted as the standard to compare animals on US base. The emphasis in NM$ is mainly on production, longevity and fitness. Compared to TPI, NM$ has a lot more similarities with the NVI formula.

CRV has a complete range for farmers who want to breed American-type cows.