In December, CRV is introducing a new breeding value for its own bulls, which will enable a targeted and direct way to breed for feed efficiency. The index indicates how much more milk is produced by daughters of a particular bull using a kilogram of dry matter feed intake, compared with the population average. Good feed efficiency also means more efficient use of nitrogen and other minerals and a lower CO2 footprint for the production of milk.
The amount of milk a cow produces in kilos from a kilogram of dry matter feed intake. This defines feed efficiency in one sentence. ‘Every farmer in the world understands what this means’, says Pieter van Goor. He is responsible for collecting and processing the feed intake data at CRV. This data is collected from sources including the five working farms in the programme. Before corona stepped in to prevent it, he accompanied excursions to these farms at least twice a week. ‘There is very high interest in feed efficiency’, the breeding technician has noted. Multiple factors determine the feed efficiency of a herd. Genetic predisposition is one of them.
Breeding value feed intake since 2016
CRV already started calculating breeding values for feed intake back in April 2016. This was joined in December 2017 by the breeding values saved feed for maintenance (SFM) and saved feed costs for maintenance (SFCM). Since April 2018, the SFCM has had a weighting of 5% in the NVI formula.
‘So farmers have been able to factor in feed efficiency in their breeding strategy for quite some while. But the explanation behind the breeding values SFM and SFCM is fairly complex which means they haven’t been used much in practice’, concludes van Goor. ‘That’s a shame, because breeding for feed efficiency has huge potential. On average, feed costs account for more than half the costs of producing one litre of milk. If breeding can help you save just a few per cent of this amount, that’s a lot of money.’
To bring how genetic predisposition for feed efficiency is expressed more into line with practice, CRV developed a new breeding value for its own bulls. ‘This gives an immediate indication of how many more kilograms of milk daughters of a certain bull produce from a kilogram of dry matter feed intake, compared with the population average’, says Henk Geertsema. In his role as a breeding technical analyst at CRV, he helped develop the breeding value. ‘The breeding value is expressed as a relative index with an average of 100. A score above 100 represents higher efficiency and a score below 100 lower efficiency than average’, he explains.
Massive economic significance
Geertsema explains how this works in practice by comparing two bulls: one with a breeding value of 100 and the other with a breeding value of 104 for feed efficiency. Daughters inherit half of their genes from their sire. This means that daughters of a bull with a breeding value of 104 produce on average 2% more milk from a kilo of dry matter feed intake than daughters of a bull with a breeding value of 100.
If daughters of an average bull produce 10,000 kg of milk per lactation, daughters of a bull with a breeding value of 104 give an average of 10,200 kg. At a milk price of €0.30, that is €60 extra revenue from milk for the same feed costs. With a herd of 100 cows that is equivalent to €6000 more income over feed costs. ‘The differences between individual bulls may seem small, but this calculation example shows that the economic potential of breeding for feed efficiency is massive’, he emphasises.
|Bull||Breeding value feed efficiency|
Table 1 – Breeding values for feed efficiency of commonly used bulls with at least ten daughters with feed intake data (source: CRV, preliminary figures)
Reliability is rapidly increasing
For young (genomic) bulls, the reliability of the feed efficiency breeding value is about 45%. This percentage increases as feed intake data from their daughters becomes available. For example, the breeding values of G-Force and Titanium, who each have 18 daughters in the feed intake programme, already have a reliability higher than 70%.
The calculation of the feed efficiency breeding value is currently based on a database containing the registered feed intake data of about 7000 cows. ‘These are the statistics we receive from various test farms in the programme where feed intake data is measured and collected for research and the five working farms where we measure feed intake ourselves’, says Geertsema. ‘These CRV working farms alone have more than 2000 cows. The database is therefore rapidly expanding, which will also boost the reliability of the breeding value for feed efficiency’, predicts the breeding specialist.
Lifetime production is also important
The heritability of the feed efficiency trait is about 0.18[SohV1] . ‘That is lower than most of the production and conformation traits, but far higher than the traits for fertility and health’, explains Geertsema. So he believes that including feed efficiency in the breeding and selection strategy is certainly worthwhile. ‘Despite the relatively limited heritability, we have seen visible progress being made in practice in recent years through targeted breeding for claw and udder health’, says Pieter van Goor by way of comparison. ‘This goes to show that a consistent breeding regime based on traits with a relatively limited degree of heredity pays dividends’, he emphasises.
Feed efficiency is not the only trait that determines how efficiently a cow converts the feed she intakes during her lifetime into milk. Longevity also plays a key role. ‘The amount of feed needed in the rearing phase can be divided over more lacations and higher milk production in kilos with a cow with high lifetime production,’ explains Geertsema. ‘The CRV Efficiency index shows the genetic predisposition for this total efficiency. In addition to feed efficiency, Inet and longevity are part of the index.’
The average feed efficiency at the participating farms is 1.46 kg of milk per kg of dry matter (dm) feed intake. From 23 kg of feed, the cows produce an average of 33.6 kg of milk every day. Daughters of a bull with a breeding value of 101 have an average feed efficiency of 1.46. From the same 23 kg of feed, they produce an average of 34.3 kg of milk. With a milk price of €0.30, that is €0.21 extra income over feed costs per day.
Efficient with forage and concentrates
Van Goor is aware of the reservations of critics. Breeding for feed efficiency is supposed to compromise the health of cows. ‘If, without thinking it over, you bred purely and solely for feed efficiency, that could indeed be the case. Feed efficiency has a slightly negative correlation to traits such as susceptibility to ketosis and daughter fertility’, he indicates. ‘But bulls that score poorly on these traits are not used. There will be plenty of bulls available that partner a high feed efficiency score with good breeding values for health traits’, according to the breeding technician. He compares this to breeding for production and fertility. ‘The Inet trait has a slightly negative correlation to daughter fertility. However, over the last ten years, increasing production while improving fertility has been a successful venture.’
No small, spindly cows
According to van Goor, the reasoning that breeding for feed efficiency creates powerful, big cows is also a fable. ‘Measurements on the farms disprove this. Cows with high feed efficiency convert both forage and concentrates efficiently into milk.’
In conclusion, the breeding technician points to the relationship between feed efficiency and stature and weight. ‘On average, cows with high feed efficiency are smaller and lighter than cows with low feed efficiency. The weight difference between the 25% highest and lowest scoring cows for feed efficiency on the participating farms is about 15 kilos’, he says. ‘But we also see in practice that a lighter cow is not by definition more efficient than a heavier cow, as long as the heavier cow produces more milk’, he explains. So in his view, farmers do not need to be worried that breeding for feed efficiency will result in small, spindly cows. ‘Production is positively linked to stature and weight. If we continue to breed based on production, cows will become larger and heavier. But if we include feed efficiency in the selection procedure as well as production, the increase in stature and weight will be slower.’
CRV is certainly not the only breeding organisation in the world that is working on feed efficiency. ‘However, we are the only organisation able to present an index based on a high volume of data measured directly from dairy cows in practical conditions’, stresses van Goor. ‘This is what makes the new feed efficiency breeding value unique internationally.’