Feed efficiency requires the correct context

category Efficiency
4
Mar
2020
0
Comments
There are variations in feed efficiency between breeds and between young and older cows.

Just a minor improvement in the milk yield from a kilo of feed has a significant impact on a farm’s financial results. So it’s hardly surprising that the feed sector and the breeding world are both investing heavily in efforts to boost feed efficiency per farm and at cow level. This series of three articles in Veeteelt outlines the developments. This is part 3: In practice.

Are Jersey cows more efficient at converting feed than Holsteins and is there a variance in the feed efficiency rates of heifers and older cows? Practical experience shows that anyone want to apply the feed efficiency index must interpret the underlying figures correctly.

‘When a dairy farm has to buy all its feed and dispose of all the manure, feed efficiency is the most vital component of the revenue model.’ These are the words of Jan Willem Elsenga, who has owned a dairy farm in the Flevopolder with no access to grazing for six years. Based on his own experiences he fully advocates the importance of feed efficiency. ‘We bought a farm with no grazing land, and with the idea of producing one million kilos of milk as efficiently as possible on that basis’, Elsenga continues. The day-to-day running of his farm is the responsibility of farm manager Pieter de Vries.

Right from the very start, the feed efficiency index was so important for Elsenga that he set up trial in his own barn. ‘We feed according to the Kempen feeding system, which allows the cows ad-lib access to concentrates. We had heard the stories about Jerseys being more efficient feed converters than Holsteins, so what we did was buy some Danish Jerseys. They were fed in one half of the barn, while on the other side we fed the Holsteins. This tactic allowed us to precisely track the roughage and concentrate intake of both groups and how much milk they produced.’

In the winter of 2016, the practical trial revealed that the Holsteins converted 25 kg of concentrate ration and 5.4 kg of dry matter as roughage into 35.5 kg of milk, whereas the Jerseys turned 17 kg of concentrates and 4.2 kg of dry matter as roughage into on average 24.4 kg of milk. The milk components produced by the Jersey cows were considerably higher, which converted to 31.4 kg of FPCM. This considerably reduced the difference in FPCM compared with the group of Holsteins (34.8 kg). Elsenga calculated a feed efficiency of 1.61 for the Jersey group and 1.30 for the Holstein group. Thanks to the higher milk payout (due to higher components) and the lower feed intake, Elsenga has now switched almost entirely to a herd of Jerseys. ‘I am prepared to confidently state that Jerseys are 25% more efficient at converting feed into milk’, says Elsenga.

Larger gastrointestinal tract in Jersey cows

Jan Dijkstra, associate professor at the Animal Nutrition Group, Wageningen University & Research, offers an explanation for the efficient (roughage) feed conversion of Jersey cows. ‘Jerseys have a relatively larger gastrointestinal tract than their Holstein counterparts. In addition, the number of chewing movements and rumination time per kilo of feed is higher and that also causes a slightly higher digestion’, explains Dijkstra. According to Dijkstra, studies show that based on kilos of fat and protein Jerseys deal between 10 and 15% more efficiently with energy from feed. However, he adds a caveat for nitrogen efficiency, which is a hot issue. ‘What nitrogen efficiency roughly means is how many kilos of milk protein are produced per kilo of protein fed. If the nitrogen efficiency is equal, but nitrogen metabolism is somewhat better, this means that relatively more nitrogen in the form of ammonia is excreted via the urine by Jerseys than by Holsteins.’

Farmers who work with production groups will also notice differences between lactation stage or age. ‘Roughly speaking, older cows have a 6% higher efficiency than heifers’, continues Dijkstra, who has drawn up a calculation model for this (see box).

Dairy farmer Thijs Rompelberg has been feeding a total mixed ration for many years and since 2014 in three production groups. The feed efficiency is calculated daily. ‘Our heifer group has a feed efficiency of 1.35 on average and the fresh cows score 1.65’, according to Rompelberg, who runs a herd of 300 cows in Eijsden with his uncle.

‘But the feed efficiency index in itself doesn’t say all that much’, he says to bring the value of the index into a sharper perspective. ‘It’s about the income over feed costs, or even better, the profit potential at the end of the line. My cows might well be very efficient feed converters, but if this is due to a high proportion of concentrate, then a more interesting option could be lower feed efficiency on a cheaper ration of roughage. The baseline situation in terms of the available quantity of feed varies from farm to farm.’

Understanding the values behind feed efficiency

In other words, you have to put the feed efficiency index in the correct context, according to Rompelberg. ‘If you happen to have a lot of fresh cows in the high production group, this will impact on the average feed efficiency. So you can’t simply compare the feed efficiency at that moment with feed efficiency a month back.’ Rompelberg says he uses the index to examine whether roughage is utilised optimally in the form of milk production. ‘If we notice any deviations, we try and trace the cause.’
Rompelberg has first-hand experience with variations in the feed efficiency of individual cows. ‘We have been feeding a TMR for years. Any cows that gain weight too quickly or cannot cope with production have now been removed from the herd. With three milking sessions a day, we currently produce 11,500 kg of milk with a feed efficiency of between 1.5 and 1.6. This suits the way we work here as we are self-sufficient in roughage and delivers good results for the income over feed costs. But, to stress the point, make sure you understand the values behind the feed efficiency index.’

 

An older cow has 6% better feed efficiency than a heifer

Young cows have a different feed efficiency than older cows. ‘A heifer has a lower body weight, so she needs less feed for maintenance. That’s a plus for feed efficiency’, says Jan Dijkstra. ‘But heifers and cows on their second calf are still in a growth stage, and that in turn has a negative effect on feed efficiency.’ Older cows have higher milk production, so the nutrient requirement for maintenance is ‘diluted’ over more milk. Dijkstra has calculated an example of the differences: ‘I used the milk production figures for a heifer, a second calf cow and older cow from CRV. The figures rounded up to: 25.0, 28.5 and 30.5 kg of milk per day with 4.30% fat and 3.55% protein.’ For the body weight he used 570 kg for the heifer, 623 kg for the second calf cow and 650 kg for the older cow. ’This resulted in a feed efficiency score, based on kilos of FPCM per kilo of feed, of 1.42 for the heifer, 1.47 for the second calf cow and 1.51 for the older cow. This means that the older cow has an average of 6% better feed efficiency than the heifer’.