Reduce the need for buffer feeding

Published 10 July 15

Grazing success depends on two things, a trained herd manager and a trained cow. Get this right and the need for buffer feeding is substantially reduced, says Piers Badnell, AHDB Dairy Technical Extension Officer.

Buffer feeding can be used during severe reductions in grass supply to meet the animal’s requirements for nutrients. However, the need for this can be massively reduced by well-managed rotational grazing, because the system allows for greater control over pasture management. For example, it allows for the accommodation of fluctuations in grass growth throughout the grazing season and allocation of how much grass you want your cows to consume based on demand and supply. This means only small changes to grazing are necessary, rather than a boom/bust situation, where there might be a need for expensive buffer feeds. For more info on rotational grazing see section 4 of Grass+.

A properly managed rotational system can give 12 ME from February to November. It also allows for the development of the third leave which provides 45% of the yield. So by slowing down the rotation, and growing the third leaf, you have more feed. Any shortfalls are limited and can be supplied by parlour concentrate.

There are two drawbacks to buffer feeding if grass is available. Firstly, cows will not graze as intensively because there is a much easier source of nutrients available in the feed trough. As the cow will not graze aggressively, it becomes more difficult for the correct residual herbage mass to be achieved (1,500kg DM/ha). This results in reduced quality and growth in subsequent rounds, leading to a need to buffer feed – a self-fulfilling prophecy. This ‘lazy cow syndrome’ should not be under estimated. When she realises there is only grass and no filled trough waiting for her she will surprise you by learning how to graze.

Secondly, the dung from a buffer fed cow can be far coarser and takes longer to break down than that from a cow on a grazing diet. As it takes longer to break down it thus increases the amount of rejection areas. As manure from a grazing cow is far looser it spreads further, providing a larger surface area on which bugs can break it down and for rain to wash it in. This will result in fewer rejection sites, leading to far better pasture utilisation. While issues around coarser manure can be alleviated, this requires tractor, rake, topper, etc, which is wasteful in terms of time, grass and cost.

In addition, good grazing will lead to better plant and root health. By slowing the grazing round early enough this enable grass to get to the third leaf stage, meaning you will have more grass available.

Small shortages are best managed using concentrate rather than buffering.

Buffer feeding often occurs because of low confidence in grass. While poorly managed grass can be of low quality and unproductive, rotationally grazed grass at 2,800kg DM/ha (2.5-3 leaves) can give 12 ME. It will grow strongly post grazing so you will end up with more quantity and quality.

The example below demonstrates the potential well managed quality grass has to offer for a cow weighing 600kg which produces a litre of milk with 4% butter fat and 3.3% protein. 

  • For maintenance, she requires 10% of body weight +10
    • 600 X 0.1+10 = 70 MJ ME
    • To produces a litre of milk at 4% fat and 3.3% protein she needs 5.3 MJ
      • If she eats 6kg DM at 12 ME grass that is 72 MJ ME. That just covers her maintenance requirement and doesn’t leave enough to produce any milk
      • Increase her intake to 10kg DM at 12 ME = 120 MJ ME, minus 70 for maintenance = 50, divide this by 5.3 = 9.5 litres
      • Raise the intake to 14kg DM at 12 ME = 168, minus 70 = 98, divided by 5.3 = 18.5 litres
      • When she eats 17kg DM (on a herd basis about as much as she can eat) at 12 ME = 204 MJ ME, minus 70 = 134, divided by 5.3 = 25 litres
      • When you know how much she has eaten, you can work out how much milk she will produce
        • For example, a pregnant cow with the potential to produce 30l of milk (4% fat, 3% protein) eats 14kg of grass this will do M+18.5l. She needs supplementation to reach her genetic potential (12.5x5.3=66 MJ required). So if you feed the cow 5.5kg of concentrate at 12 ME, her requirement is met.

A Cows’ daily energy requirements depend on their specific requirements for maintenance, reproduction, milk production and body reserves. For more information on how to calculate her requirements, see section 7 of Feeding+.

To recap: avoid buffer feeding, as it will add cost, reduce her desire to graze and as she is away from grass for longer it reduces her time to graze, compounding the problem. So unless you are severely short, buffer feeding is an option. Otherwise, train the cows how to graze and make more money.