Dairy Herd Nutrition - an Entree


  • A cow can eat about 85kg of grass and chew up to 41,600 times a day
  • To produce 17 litres of milk a cow needs to drink 50 litres of water.


System 1 - All grass self-contained, all stock on the dairy platform. No feed is imported. No supplements fed to the herd except those harvested off the effective milking area and dry cows are not grazed off the effective milking area.

System 2 - Feed imported, either supplement or grazing off, fed to dry cows. Approximately 4-14% of total feed is imported. Large variation in % as in high rainfall areas and cold climates such as Southland, most of the cows are wintered off.

System 3 - Feed imported to extend lactation (typically autumn feed) and for dry cows. Approximately 10-20% of total feed is imported.  Westland - feed to extend lactation may be imported in spring rather than autumn.

System 4 - Feed imported and used at both ends of lactation and for dry cows. Approximately 20-30% of total feed is imported onto the farm.

System 5 - Imported feed used all year, throughout lactation & for dry cows. Approximately 25-40% (but can be up to 55%) of total feed is imported.

 *Note: Farms feeding 1-2kg of meal or grain per cow per day for most of the season will best fit in System 3.


Providing your herd with good quality pasture is one of the most cost effective ways to get the most production out of your cows. Grass management becomes a necessary skill to get the most out of it and ensure you have sufficient for the rest of the season by grazing it off and making hay/baleage/silage out of any surpluses grown. That’s not to say that it should be all grass, all the time. Depending on the quality of the pasture and the nutrients it may provide, there can be a need to add minerals to your herd’s diet at certain times in their annual cycle for optimal production e.g. magnesium around calving time. The seasons play a part in this too; during the cold, wet months of winter, pasture growth will be minimal so providing supplementary feed  will be necessary, often with crops such as kale or fodder beet and with conserved feed e.g. silage and hay.

Read this interesting resource from Lincoln University which covers how pasture grows, what constitutes quality pasture, and how to measure quantity and quality.

Let’s run through a couple of the commonly used supplementary feed options and the things you need to look out for:


PKE is a commonly used imported feed supplement especially popular when needed to fill a deficit in the farm’s feed production i.e. when a drought is in effect. Fonterra has issued guidelines recommending the limiting of its consumption to 3kg/cow/day. PKE is easy to procure, available all year round, and has no major animal health risks.


Grain is most commonly fed through in-shed feeding systems installed in the dairy shed feed. It can have added costs as it needs to be crushed before feeding; silo stored; and there’s needs to be added infrastructure on the farm for in-shed feeding.


While younger cows do need straw as part of their diet to aid the development of the rumen, mature cows do not. A diet including straw is not as nutritious, and much lower in ME (metabolic energy) than one with high consumption of ryegrass. It does find a place in a dry cow’s diet especially when they are consuming high intakes of sugar/starch.

To read more about this, here’s a great article that ran in the Timaru Herald a few years ago about a seminar where experts from Lincoln University and Synlait busted the myths around dairy cow nutrition.


Fodder beet, if managed well, can produce up to 30 tonne/ha which makes its cents/kg/dm cost extremely competitive with other forms of supplement. A potential issue with fodder beet is acidosis; this is when there is too much digestible starch in the rumen, causing too much acid that kills off the bacteria and feed is not digested. Fodder beets need to be transitioned into the diet so the bacteria get used to it. Clutha Vets recommend introducing this new feed slowly over a period of two weeks or more.


When ryegrass is not available in abundance there are plenty of other options to keep cows fed and healthy. Dairy NZ Crops page is an excellent source of knowledge on crop alternatives.


  • Save your pastures from damage caused by trampling.
  • Keep your herd warm, fed and milking further into the winter season.
  • Set and control feed levels based on a reliable, quality supply of feed.
  • Improve herd health by maintaining optimum weight.
  • Closer monitoring of the herd allows you to notice any changes in eating habits or overall health faster and easier.