Heifer feeding and nutrition

Nutritional requirements of heifers

Well managed ryegrass pastures are a complete diet for heifers at all stages of life, including leafy kikuyu pastures. Heifers should be fed diets of 10.5MJ ME and the appropriate protein to ensure that they meet liveweight targets.

Heifer liveweight gain is the best indication of meeting nutritional requirements as well as adequate minerals and water provision. Farmers should focus on meeting key weight for age liveweight targets for heifers rather than a particular pattern of weight gain.

Nutrition pre-puberty (before 50% mature liveweight) is where skeletal growth is influenced, if R2 heifers are significantly shorter than mature cows pre-calving it will be due to feed management pre-puberty.  

Energy and protein required (eaten) for maintenance and growth in heifer diets

*Energy does not account for energy required for pregnancy

The required protein percentage of the diet declines as the heifer gets heavier because the relative weight gain slows down.  For example, a heifer would double her liveweight in her first three months of life, but typically it takes another nine months before she doubles her weight again.

Nutritional stages

• Weaning to nine months of age. Focus on lean growth (muscle and skeletal) and not overly fat heifers, achieving 30% mature liveweight at six months. Lean growth results in increased frame size while maintaining a consistent body condition score. Improved skeletal development results in taller heifers that experience fewer calving difficulties. Rumen capacity can limit at this age so high energy and high protein diets are critical.  Try to capitalise on energy efficiency when heifers are young. 
• From nine months to mating at 15 months of age. Focus on heifers achieving puberty (43-47% mature liveweight) one to two months pre-mating and continued growth to mating (60% mature liveweight at 15 months) to improve conception rates.
• 15 months of age to 24 months. Liveweight should be gained over this year targeting 90% of mature liveweight at 22 months and 5.5 body condition score pre-calving. Cow condition reflects how well an animal has been fed for the last 6-8 weeks where body weight relative to liveweight targets is how well the heifer has been fed over her life.  

Everyday feed requirements for heifers

The below table shows the required daily feed intake

* This table is for feed eaten, feed offered needs to account for wastage. 

* This table does not include walking/ hard hill/ unfavourable weather and is based on feed quality of 11MJME/kg. Add/subtract  10%  per MJME for diets below/above. Add additional 5% for rolling to steep land.

*Pregnancy requirements: Requirements for different stages of pregnancy based on calf born at a weight of 30 kg. 1705 total MJME for pregnancy (assumes 11 MJME).

• Water requirements

  The below table shows the average required daily water intake of heifers

  Bodyweight (kg)	Litres per day
  45	3.5
  90	11
  180	19
  270	26
  360	32
  455	38

• Mineral requirements

  Mineral requirements of growing young stock will vary by farm and region. Look at soil types, pasture fertiliser history, and types of crops or supplements being fed. Speak to your vet about developing a mineral supplementation plan.

Heifers and crops or supplements

Supplementing pasture may be required to maintain heifer growth. If pasture is limited, it is cost effective to feed heifers crops and supplements. Supplements for pasture diets should contain at least 11 MJ ME/kg dry matter and crude protein suitable to meet the animal’s nutritional stage.

Animals may gain slightly more weight from supplement feeding, but the weight gain is rarely economical.  Supplementation may be justified if heifers are behind liveweight targets and need to achieve weight for age targets before the end of a contract. Short term supplement feeding can also be beneficial if it helps increase pasture growth rates to fill feed shortfalls and reduce the amount of supplement needed overall.

You may see an increase in heifer liveweight gain from crops or supplements, this is a result of increased feed supply, not an increase in feed quality or crude protein content.

• Risks of crops and supplements

  Feeding crops and supplements will reduce animal health risks associated with pasture (such as ryegrass staggers) but have risks and limitations of their own.

  Crops and supplements typically require rumen transition and may have issues with palatability, nutritional composition, mineral composition, differences in feed management, suitability to the wider system, or low yields. Take these aspects into consideration when choosing a crop or supplement to feed.

• Choosing and feeding crops and supplements

  Nutritional considerations of crops and supplements

  • Avoid sudden changes in diet, rumen transition where required (specific to feed type)
  • Adequate fibre in the diet is critical for rumen function, at least 10% of the diet must be a fibre source.
  • Supplements are often higher dry matter than pasture so make sure sufficient water is available, water limitations will depress heifer growth rates and is a risk to animal welfare.

Compensatory growth

It is dangerous to rely on compensatory growth as it varies for each animal. Compensatory growth rarely makes up the difference for mobs to meet target weights and fails to close liveweight gaps. Using supplements and crops when pasture is limited increases the chances of heifers reaching target weight.