As with milk protein, the level of milkfat and how this changes through a season can provide insights into aspects of herd management.  

The following table summarises the effects certain management factors have on milkfat and milkprotein;

Factor	Fat	Protein
Genetics	Jerseys higher % than Friesians	Jerseys higher % than Friesians
Stage of lactation	% increases as lactation advances	% increases as lactation advances
Low BCS at calving	% reduced	No major effect
Low rumen fibre / acidosis	% reduced	No major effect
Feeding of bypass proteins	No major effect	% increased
Low dietary energy intake	No major effect	% reduced

When these factors are well-controlled, milkfat percentage graphs over a season will present a steady curve that rises as the season progresses with minimal day to day fluctuation (see Farm A graph).  Sudden drops in milkfat percentage need to be avoided as these indicate an unstable and potentially acidotic rumen (see Farm B).  Similarly, running very low or declining milkfat percentages for extended periods can be indicative of a more long-term dietary issue; subacute ruminal acidosis (SARA).  SARA is usually a herd problem causing variable feed intakes and reduced milk production with very subtle clinical signs.  Long term consequences associated with this condition are abomasal ulceration, liver abscesses and laminitis/lameness.  Of high importance therefore is the consistent feeding of a diet balanced for rumen health combined with regular monitoring of milkfat levels.

Farm A

Farm B

Interpretation of fat and protein graphs can be challenging, however when done properly can provide an accurate assessment of not only farm performance but herd health.  Please don't hesitate to talk to us if you are at all concerned about your current performance or are interested in viewing your graphs.