It is derived from the nut of the palm fruit after the oil is either mechanically extracted (most PKE imported to NZ) or solvent extracted (lower nutritive value).
Fonterra has announced the introduction of a Fat Evaluation Index (FEI) Grading System to come into force from September 2018. Earlier in 2017, the company started informing farmers of their Fat Evaluation Index results on milk dockets. This index was designed to indicate the suitability of the milk fat composition for processing into a variety of products.
DairyNZ has pulled together information to help farmers understand the FEI and manage their PKE feeding levels so that their milk is fit-for-purpose. For more information from Fonterra visit nzfarmsource.co.nz.
What is the fat evaluation index (FEI)?
This index is designed to indicate the suitability of the milk fat composition for processing into a variety of products.
The link between FEI and PKE use has been researched by AgResearch and DairyNZ with funding from Fonterra and Ministry of Business, Innovation and Employment (MBIE) in the Pastoral21 programme.
Studies with dairy cows at different lactation stages, supported by computer modelling, shows a very strong relationship between the amount of PKE fed and the FEI number. The strength of the relationship is so good that the simplest way to predict the FEI of your bulk milk is to know the average PKE intake of your milking herd (on a per cow basis). However, it is important to note that several other factors including breed of cow, other feeds fed, and environment also influence the fat composition of milk.
What impact does PKE have on the make-up of milk?
PKE is an important feed option that many farmers choose to use in their farming systems. However, feeding PKE to lactating cows changes the amount and the ratio of the fatty acids in the milkfat. At high levels of PKE-feeding, the milkfat becomes difficult to process and meet customer requirements for other products.
According to Fonterra’s grading system, what grade indicates that my milk is suitable for processing?
A Meets requirements B Meets requirements but is approaching the FEI threshold limit C Exceeds FEI threshold limit D Well in excess of the FEI threshold limit
While 3 kg/cow/day for milking cows is a good ‘rule of thumb’ to maintain A or B grade FEI, to a lesser extent farming system, breed, other supplementary feeds, milk yield and time of year can also slightly influence the numbers. Some farms may be able to feed more than 3 kg/cow/day while others may hit the threshold at less than this.
The research has also shown that different PKE shipments have different fat levels. Farmers should expect some variability in shipments across the season and also if they change PKE suppliers.
What happens if I reach the limit for the FEI?
One way to decrease your FEI, is to feed less PKE per milking cow, either by reducing feed levels or by replacing PKE with more pasture or another supplement. No other commonly used supplements have as significant an effect on the FEI as PKE. However, even a 100% pasture diet will register an FEI. Summer brassicas also will elevate the FEI slightly. DairyNZ tools such as the Autumn Management Tool and Supplement Price Calculator can help with these feeding decisions.
What about dry cows and young stock?
The research has shown that feeding dry cows even high levels (7kg DM/cow/day) of PKE has no effect on subsequent lactation FEI. The FEI Grading System does not apply to feeding your young stock. So drying some cows off or 'moving feed' around your system may also achieve the target.
What happens if I feed large amounts of PKE, what options do I have?
On farms where large amounts of PKE are routinely fed longer-term, decisions such as changing stocking rate or supplement type will need to be considered.
Why has DairyNZ become involved in FEI?
DairyNZ are one of the organisations that conducted the research to examine the link between feeding PKE and changes in the composition of the milk. As a farmer-funded, industry good organisation we are tasked with helping farmers understand and respond to any changes in the dairy industry such as new guidelines and recommendations.
nderstand and respond to any changes in the dairy industry such as new guidelines and recommendations.
More about PKE
PKE is a dry, gritty meal with a soapy smell and has low palatability until cows get a taste for it. However, PKE has reasonable levels of energy (ME) and protein, and is relatively easy to introduce to cows over a range of farm systems.
The profitability of PKE is dependent on the price of PKE relative to milk price and the utilisation of PKE and pasture.
Is palm kernel a low digestibility feed and should it matter?
There is no single, ideal measure of feed quality. However, in New Zealand, metabolisable energy (ME) is the factor limiting milk production in the majority of situations. Therefore, ME content (MJ/kg DM) is the best measure of feed quality for most farmers to use. It does not matter whether a supplement contains fibre, starch or sugar. The cost of each MJ ME should be how you decide which supplement to purchase.
Palm kernel extract contains about 11.0 - 11.5 MJ ME (mechanically extracted) and is, therefore, a reasonable quality feed for dairy cows when short of pasture.
Question: I have been told that palm kernel extract (PKE) should be avoided as a feed for dairy cows because it has a low digestibility (approximately 50%) and, as a result, will not promote the growth of rumen microbes. Should I buy a different supplement?
Answer: No, and here's why.
Cows survive and produce on:
a. The waste products of rumen fermentation (volatile fatty acids)
b. The micro-organisms that have grown during rumen fermentation, and
c. The feed that was not fermented (i.e. bypasses the rumen).
As a result, there are multiple measures of feed quality, including:
- How much is digested (digestibility)
- How much energy is available for production (metabolisable energy or net energy)
- How much protein is in the feed (crude protein, true protein, soluble protein)
- How much fat is in the feed
- Minerals and vitamins.
All of these are important to varying degrees, depending on what is lacking from the diet.
The digestibility of the feed refers to how much of the feed is digested in the rumen (rumen digestibility or rumen degradability) or along the entire digestive tract (dry mater digestibility). The rumen digestibility of a feed is important for determining the growth of rumen micro-organisms. These supply protein and some energy to the cow. However, there is a long digestive system after the rumen, in which proteins, fats and some sugars are digested and absorbed. Therefore, dry matter digestibility is a better measure of feed quality as it takes into account the whole digestive system and not just the rumen. Metabolisable energy is estimated from some measure of dry matter digestibility.
Protein is important because it provides the rumen micro-organisms with nitrogen to grow, the protein that bypasses the rumen is used directly by the cow, and because it also provides some energy.
Fats and oils cannot be used by the rumen micro-organisms and, therefore, do not promote microbial growth. They are instead used directly by the cow as an energy source.
What about PKE?
Palm kernel is not very digestible in the rumen. Estimates of rumen digestibility range from 50 to 60%. However, this does not accurately portray the feed value of PKE for dairy cows. The feed value in PKE comes from the ruminal digestion of fibre, some ruminal digestion of protein (55 to 60%), the protein digested in the small intestine (40 to 45%), and the fat, although the minerals are also important.
In the vast majority of situations, grazing dairy cows are short of ME. They are only rarely short of metabolisable protein (that is protein that reaches the small intestine). Therefore, changing supplement to increase the growth of rumen micro-organisms to further increase metabolisable protein will not be beneficial.
Metabolisable energy is the most important measure of feed quality for New Zealand farmers. Laboratory analyses indicate that PKE has an ME of around 11.5MJ/kg DM because of its relatively high fat content, its reasonably digestible fibre, and its protein content. However, as PKE is a by-product, this figure will vary and farmers are encouraged to have their feeds tested by a reputable laboratory. The practicalities of what supplement can be fed should be considered (e.g. liquid vs dry feed, in-shed feeding vs feeding in paddock). Supplements should only be offered to cows that do not have sufficient pasture (i.e. residuals are less than 7 to 8 clicks on the plate meter) and every effort must be made to minimise wastage.