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BEAT THE DROP: Combatting a drop in butterfat

BEAT THE DROP: Combatting a drop in butterfat

Manage and maintain butterfat in early-mid lactation.      

A decline in butterfat percentages can be common during the spring months, when cows are grazing lush grass that is low in fibre and high in oil and sugars, among other reasons. The Alltech nutrition team focus on four key areas to combat a drop in butterfat, including:

  1. Nutrition

We generally see a high percentage of solids for the first 6 weeks post-calving, then a drop in protein and butterfat replicated further on in the lactation. If protein percentages are fluctuating or dropping quickly, this is usually a symptom of reduced intake of energy, which leads to poor body condition and prolonged negative energy balance post-calving. It is important to maintain a body condition of >2.75 or avoid a drop >0.5 units post-calving until breeding. If below this, action must be taken to correct it as on top of milk solids drops, there could be adverse effects on fertility.

Protein percentages will also be driven by the quality of feeds fed in the form of starch and sugar content and the total quantity of these ingredients or dry matter intake (DMI). Starch content usually coming from grain and sugar content will be high in grazed grass. Cows should be fed to their requirements consistently. For example, a cow that will peak over 30 litres would have an expected DMI of 19–21 kg DM. Where there is a shortfall here, it needs to be supplemented, or you run the risk of a protein decline.

Butterfat will be dictated by the energy levels in the rumen. Cows on high amounts of poor-quality forage can experience butterfat depression due to the lack of rumen-degradable energy. Fibre levels will also drive milk fat, with straw being a more effective fibre than silage and silage being more effective than grass. It is not always possible to include long, effective fibre when cows are at grass, so extra attention needs to be placed on the parlour feed by including high levels of digestible fibre and, ideally, no more than 3 kg per cow per milking

  1. Rumen health

A key factor for the occurrence of butterfat depression is an elevated intake of unsaturated fats from young, leafy grass. Unsaturated fats are toxic to rumen bacteria, and in order for them to survive, they carry out a process called ‘biohydrogenation’. This, in turn, creates by-products that, in effect, stop the mammary gland from producing butterfat, leading to butterfat depression.

This effect can be exacerbated in the presence of a low rumen pH. Fresh, lush grass can cause a drop in rumen pH, which leads to sub-acute rumen acidosis (SARA). If the pH is below 6, bacteria will not work as effectively. This can harm both feed intake and digestion, leading to depressed milk production.

Avoiding conditions that can lead to SARA and improving rumen pH are central to ensuring that the rumen is working at its best, optimising the breakdown of grazed grass and concentrate, as well as improving nutrient availability. Research shows the correlation between pH and milk fat percentage is very important, the higher the rumen pH the higher the milk fat percentage. BEAT THE DROP and manage and maintain butterfat in early-mid lactation by ensuring Yea-Sacc® is included in your feed. Yea-Sacc, a live yeast from Alltech — is proven in Irish grass-based systems to maintain rumen stability, increase efficiency and help cows avoid the wide variations in rumen pH that can interfere with fibre digestion and feed intake. Yea-Sacc works by removing air/oxygen from the rumen and increasing the presence of fibre-digesting bacteria. This helps reduce acidity in the rumen and increase the pH. This is all about supporting rumen health, performance and efficiency, helping to optimise feed and milk production.

Figure 1: Relationships between rumen pH and percentage of milk fat (Allen, 1997).


YEA-SACC® research has shown:

  • Increased milk production — 1.7 litres
  • Improved feed conversion efficiency — 6%
  • Help reduce the number of days open
  1. Grassland management

The focus of any grassland management is to grow and utilise as much grass as you can. Grazing covers of 1,300–1,500 kg DM/ha (8–9 cm), or what was outlined in the past as “the three-leaf stage,” should be the target on the majority of farms. Correct graze out of paddocks in the first round of grazing will result in higher-quality, lush grass growing in the second round. Grazing these covers down to 4–5 cm will promote quality further into the year. As outlined earlier, this will increase the oil and reduce the fibre content of the grass. While this promotes good milk and protein yields, it needs to be managed from a butterfat point of view and having a healthy rumen to deal with this is key.  

If supplement is required, and this will be dictated by milk yield and requirements, we should target getting 16 kg of grass DM into our cows. High yield, weather, availability and stocking rate will determine whether extra supplement or a forage-based buffer is required.  

  1. Genetics

While addressing a drop in milk solids in early lactation, you would usually need to consider a holistic approach around balancing nutrition to ensure good rumen health and monitoring the cow’s physiological state. Longer-term benefits can be achieved by examining your genetics and reviewing your breeding policies. A good start would be to review your EBI report via ICBF, no matter what type of cow you have. This will tell you whether you have bred for increased solids production in your current herd or in the generations to come. This will allow you to make informed decisions for the upcoming breeding season.


If you feel your cows are not performing to their optimum level, call our InTouch nutritionists ‘MILK SOLIDS HELPLINE’ on 059 910 1320 for information on how you can BEAT THE DROP.

BEAT THE DROP webinar: Click here to watch.