Tips on getting the most out of suckler cow dry cow rations

Getting dry cow rations right for spring calving sucker cows is crucial in the coming months, as getting it wrong can result in poor calves and lower quality colostrum.

Straw may be as much as 80% of the dry cow diet, but to use it successfully, farmers must understand its limitations, says Karen Stewart, SAC Consultant. It is low in energy, protein and very deficient in minerals.

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However, as dry suckler cows have low nutrient requirements, it can work, but to achieve the maximum energy value from straw it is vital to add protein to the diet, as Ms Stewart explains.

“Rumen bugs need rumen degradable protein (RDP). If you don’t feed the bugs [with RDP], they won’t digest straw into a form where energy can be used by the cow.

Straw contains 6.5MJ/kg DM and needs enough protein to utilise the energy. If there is not enough available, there will be a 30% decrease in energy in the diet.”

Guide to feeding straw-based diets

  • Diet must contain 9% protein (minimum) to feed rumen bugs
  • Straw must be clean and palatable
  • Supply plenty of clean water
  • Ensure good access to supplementary feeds and straw – don’t put ring feeders in a corner
  • Ensure mineral supplements are suitable for suckler cow straw diets with good levels of trace elements and vitamins
  • As cows approach calving, consider adding silage to straw for a smooth transition

This will result in the cow losing more weight than expected over winter as lean muscle is mobilised in the absence of fat. It can also cause rumen impaction, adds Ms Stewart.

Other complications of low protein are poor calves born from thin, weak cows and lower quality colostrum resulting in long term effects on fertility.

“The average weight of cows should be known as well, as there is a big difference in maintenance between a 600kg and an 800kg cow (about 16MJ).”

Any that are over-fit will need fewer supplements, so the protein content of the diet needs to be higher, she adds.

Out-wintered cows will also require 10-15% more energy and this needs to be factored into the diet, adds Ms Stewart.

Diet advice

Ms Stewart advises a minimum of 9% crude protein in the diet dry matter (90g CP/kg DM).

Liquid urea is suitable for fit cows, but thinner or close-up cows may require a different source of protein. Straight molasses does not contain enough protein – it needs to have urea in it, she adds.

“There is no evidence to say small quantities of soya in the run up to calving has any benefit, but anecdotally farmers have reported improved colostrum quality.”

The straw itself can vary depending on type. However, a useful guide is to look at the ratio of stem to leaf. A higher leaf-to-stem ratio will improve digestibility and lead to higher voluntary intakes, says Ms Stewart.

Ammonia treated straw increases digestibility and energy value of straw and requires little or no supplementation with energy or protein for the cow in good body condition.

However, high levels of suckler cow minerals are important and should contain 2-3% sulphur, which is needed by the rumen bacteria.

Ms Stewart also warns thin cows will still need supplementation with ammonia treated straw. It is also insufficient for dry cows in the close-up period to calving.

Straw-based diets for a 650kg suckler cow, eight weeks from calving, losing 0.25kg/day (kg freshweight a day a head)

 

A

B

C

D

Straw ad-lib

9.5

9.5

9.5

7

Barley

0.5

     

Rapeseed meal

1.8

     

Pot ale syrup (PAS)

 

4.0

   

Wheat dried distillers grains (WDDG)

   

2.2

 

Draff

     

15

Minerals

Yes

Yes

Yes

Yes

COST/DAY*

88p

75p

88p

73p

*Costs (excludes minerals): Straw £50/t, rapeseed meal £195/t, barley £110/t, PAS £70/t, WDDG £185/t, draff £25/t.