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Supplementation in late lactation

If you have studied the DairyNZ Economic Survey data over a number of years like Wales and Kolver (2017) and concluded that supplementary feeding cows is good for profitability/ha, return on assets and equity growth, when is a good time to increase supplementary feeding?

Whatever system you currently follow, I think the last 3 months of lactation are an ideal time to give cows more feed because they are:

  • Free from the metabolic issues and a slow rise in dry matter intake which limits them in early lactation.
  • Free from the pressures of trying to mate whilst eating pasture, which is also trying to reproduce.
  • Past the challenges of summer such as heat stress and facial eczema.

Late lactation provides a great opportunity to increase milk volumes and set cows up better for the next lactation.

As indicated by the DairyNZ Key Performance Indicator table (see below), a key benefit of increased feeding is increasing the days in milk. Although cows fed more produce more milk, they typically have additional energy and protein to partition to recovering weight (from muscle, fat and bone density) and can be dried off later, provided supplements are high quality.

A 500kg cow needing to gain 0.5 BSC over 90 days needs to gain about 200g/day, requiring about an additional 10MJ ME per day, so high quality supplementary feed is usually the best complement to high quality autumn pasture.

Substitution will mean that when fed supplements, the pasture intake per cow will drop slightly but managed properly, in the long-term, the pasture eaten per hectare should be the same across all systems.

DairyNZ’s Dairy Cow Annual Requirement table suggests that cows giving 400kgMS need to eat an extra 700kgDM at 11 MJME/kgDM to increase milk production by 100kgMS – a response of 142gMS/kgDM – which is why supplementary feeding has been so beneficial in terms of profits and efficiency.

Where herds have never received supplementary feed before, the response in the vat may be subdued as they divert more of the additional nutrients into growing and body condition. I think it is better to introduce cows to supplements in late lactation to increase income, rather than leaving improvements to the dry period or early lactation when conditions may work against you.

Where cows have been fed supplements in the spring, feeding in the autumn is likely to increase the days in milk and reduce the decline in milk produced per day. System 4 and 5 farmers should be planning to feed through autumn but may wish to review which supplements and feeding levels are most appropriate this year. In-shed feeding provides a convenient, low-waste and reliable way to deliver high quality supplements to cows.

With the introduction of Fonterra’s FEI and exceptional grass growth in some regions this season, we are seeing a move away from straight PKE towards blends and compound feed.

For further information, contact your local Nutrition Specialist who can recommend the best available options in each region.

Wales and Kolver. (2017). Challenges of feeding dairy cows in Australia and New Zealand. Animal Production Science, 57, 1366-1383.

Article supplied by Dr. Rob Derrick, Lead Nutritionist.

Key performance indicators by farm system according to DairyNZ

  Cow liveweight System 1: No imported feed System 2: Imported feed
for dry cows


System 3: 10-20% imported feed System 4: 20-30% imported feed


System 5: 25-40% imported feed


North Island and unirrigated 400 300-320kgMS 300-320 kgMS 320-340 kgMS 340-360 kgMS 360-420 kgMS
500 375-400 kgMS 375-400 kgMS 400-425 kgMS 425-450 kgMS 450-525 kgMS
Canterbury and Southland 400 320-340 kgMS 340-360 kgMS 360-380 kgMS 360-420 kgMS
500 400-425 kgMS 425-450 kgMS 450-475 kgMS 450-525
  Days in milk 230-250 240-260 245-265 265-280 275+

Adapted from DairyNZ Facts and Figures (Ed 1).