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Considering Grazing

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4 min read

How many heifers can be run? Managing feed flow Managing multiple stock classes Heifer grazing contract terms Infrastructure

Heifer grazing involves estimating your farm's ability to support the growth of dairy heifers to meet their target weights. It's important to evaluate the number of heifers your land can sustain based on the amount and quality of pasture. You must then plan feed allocation and supply throughout the year, taking into consideration potential surpluses and deficits. Be wary of grazing multiple stock classes with similar feeding priorities in the same area, as this may jeopardise production and profit. Common grazing contract terms vary by heifer age, and your farm's characteristics and management skills should guide your choice. Lastly, having suitable infrastructure, like water supply, fencing, quality pasture, and cattle yards, is crucial for effective heifer grazing.

If you are considering grazing dairy heifers it is important to assess whether your farm system can grow heifers to meet their target liveweights.

How many heifers can be run?

As a starting point, annual feed supply and demand can be used to assess how many heifers can be carried on farm.  The assumption in this process is that heifers are being grazed on an allocated block within the farm. To determine how many heifers can be run:

  1. Assess the proportion of the farm that is suitable for growing heifers.
  2. Estimate the annual amount of pasture grown on the allocated land class.
  3. Estimate level of pasture utilisation (pasture eaten/ha).
  4. Calculate total utilisable pasture available = Annual pasture production X % Utilisation.
  5. Calculate potential number of heifers carried based on annual heifer feed requirements.
  6. Factor in some flexibility with trade stock as part of base stock numbers.

How should I manage the flow of feed throughout the year?

Heifers require high quality feed, especially from weaning to nine months. Managing surplus pasture to maintain quality is critically important to the success of growing heifers.  Feed supply can be manipulated with options such as supplement feeds. To help manage the flow of feed throughout the year:

  1. Calculate monthly feed requirement per hectare on the heifer block.
  2. Estimate monthly pasture growth rates.
  3. Review feed demand vs. supply.
  4. Identity period of feed deficit and surplus. Consider options to fill feed deficits and manage feed surplus.
  5. Select an option that best suits the farm, resources available and farm management.

Managing multiple stock classes

If grazing multiple stock classes it is important to consider planning feed allocation.

  1. Set feeding priorities and plan to feed these stock classes first.
  2. Monitor liveweight gain and modify plan if required.
  3. Decide what type of feed is most suitable for each stock class.

It is a risky farm policy when multiple classes of stock that have similar priority ‘windows’ are grazed on the same allocated area. Establishing a dedicated enterprise area within the farm for stock, supported with a feed budget, reduces the risk of compromising stock at a priority time and compromising production and profit, secondary stock classes can then be used strategically to manage residuals or parasite burdens.

Heifer grazing contract terms

The most common contract periods for heifer grazing are:

  • R1 grazing: 3-10 months of age often November/December to May.
  • R2 grazing: 10-22 months of age typically a 'May to May' contract.
  • 18 month grazing: 3- 22 months of age, weaning to following May.
  • Winter grazing: 22-24 months of age, May to pre-calving.

There are strengths and weaknesses in each age group for management. Management skills, farm contour, and stock handling will influence which age group is most suited to the farm.

Managing 3-10 month (R1) age group

Heifers post-weaning (3-6 months) have one weight for age target, 30% of mature liveweight at 6 months.

During 3-10 months heifers need to:

  • Become fully developed ruminants
  • Grown to their liveweight target so they are “on track” for achieving puberty and mating liveweights

Critical success factors for this age group are:

  • Rumen development pre-weaning and transition to forage diets completed.
  • Weaning weights or minimum arrival weight for heifers to get off to a good start.
  • Standards for transport and transition are met.
  • Active animal health program to minimise parasites and protect against disease with vaccinations.

10-22 months or ‘May to May’ contract

There are two industry weight targets during this stage of life, 60% of mature liveweight pre-mating (15 months) and 90% of mature liveweight pre calving (22 months) as well as pre-calving body condition score target of 5.5.

Critical success factors for this age group are:

  • Managing feed supply relative to heifer demand to ensure adequate feeding levels.
  • Implementation of the animal health programme and regular animal health monitoring.
  • Achieving 50% of mature liveweight to trigger puberty 1-2 months prior to mating.
  • Good practice mating management.
  • Meeting weight and BCS targets at the end of the grazing term.

Infrastructure

Heifer grazing requires specialist infrastructure to aid in achieving heifer liveweight targets.

Fresh abundant water supply

Ideally a reticulated water system with trough access for heifers. Avoid putting heifers in paddocks where the trough is on a hill, slope, or erodible area that makes it difficult for a heifer to reach.  Sufficient water flow should be able to provide ten litres per heifer/hour.

Appropriately subdivided paddocks with adequate fencing

To manage feed quality and quantity, subdivide paddocks or set mob sizes so that paddocks are grazed out within three to four days over the spring and summer. If paddocks take longer than three to four days to graze, heifers will be back grazing and suppress pasture re-growth.

Heifers are curious and are more prone to misadventure than older cattle, so any risk areas should be securely fenced off. Heifers are also prone to chew on plants/trees/rubbish and increase their risk of injury or ill health.

Quality pasture

Ideally average feed quality should not be below 10.5MJ ME for dairy heifers to meet target liveweights. Not all pasture species provide the quality feed necessary to achieve heifer growth rates.

Cattle yards with a race and scales

Cattle yards improve the safety of animals and people working with them.  Well-built and designed yards allow safe access to cattle. Cattle yards are critical infrastructure for weighing, administering animal health treatments, artificial insemination and pregnancy diagnosis. Safe weighing practice should be a high priority to farmers managing dairy heifers. Key elements include concrete floors, a raised walkway, a drop rail, a head bail or crush, multi-way drafting, a loading ramp and possibly water access.

Scales should be considered a “tool of the trade” for heifer graziers. There are a variety of scales available.  While some veterinary practices offer portable scales for rent or use with their clients; other vet practices offer heifer monitoring services which can also be sourced from grazing or weighing companies and some stock agents. Hiring or employing a third party can reduce capital expenses.

Last updated: Sep 2023
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