There has been a decrease in milkfat as compared to the earlier years. For farms that are paid on component, slipping milkfat production means lower profitability for the farm. Here are some factors affecting milkfat production:
There are many factors that affect milkfat production such as rumen buffering, ration fat source and so on.
Reduced rumen pH to highly fermentable diets seems to be the biggest contributor for low milkfat production.
This is mainly due to today's diet having more fermentable carbohydrates with minimised fiber.
Variable feed ingredient quality will also affect ration performance which lead to rumen upsets due to fluctuating pH levels.
The length of time where pH is low (below 5.5) will affect clinical and subclinical cases of rumen acidosis as well is affect milkfat production.
While feeding high-grain and low roughage rations will increase milk production, it will also depress milkfat percentage, especially when roughage is restricted to 30% or less of the dry matter.
In general, it is recommended to include ground, rolled, heated and steam-flaked grain as it increases starch digestibility and propionic acid production in the rumen.
Furthermore, variable amounts of fatty acids from feeds like dried distillers grains with solubles, gluten or other oilseeds, combined with increasing dietary starch and fermentable feeds will cause lower milkfat production.
Optmising milkfat production
Here are some steps to overcome low milkfat production and increase herd performance:
1) Increase inclusion rate of rumen buffers
Recommended inclusion rate for sodium bicarbonate is around 0.75 -1% of TMR dry matter.
Rumen buffers will help to stabilise rumen acids, increase feed intake while reducing off-feed outs and improve rumen performace.
Rumen upset from insufficient buffering will cause acidosis, which is the main contributor to lower milkfat production.
2) Better manage dietary cation-anion difference (DCAD) levels for high-production and fresh cow diets
Studies have shown that dairies should take advantage of increase dietary cation-anion difference (DCAD) levels.
Increasing DCAD would help improve milkfat %, rumen pH and also higher neutral detergent fiber digestibility (NDF).
Research have also shown that potassium can help reduce the incidence and severity of lower milkfat production, allowing more of the desirable rumen biohydrogenation pathway to occur.
3) Use wet chemistry to get a more accurate ration nutrient levels
Do not rely on book values as nutrient values of various feedstuffs are not consistent from load to load.
Also, consider alleviating overcrowding whenever possible to prevent cows from slug feeding as it will affect milkfat production.
Reduce mastitis incidence and step up feed mixing and delivery management to improve milkfat production.