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Rearing heifers for longevity

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article image Trish Lewis, Consultant Nutritionist

On the subject of successful calf rearing and getting cows back in calf, Consultant Nutritionist Trish Lewis observes that getting this stage right will ensure heifers remain in the herd for more than two lactations and give a good return on the cost of rearing them.

Assessing performance

There are three useful parameters for assessing the heifer rearing program: Liveweight – heifers should be 85% of mature weight at first calving; Calving pattern – 73% of heifers should be calved by week three and 92% of the herd by week six; and Production – average heifer milk yield should be 83% of that produced by the mature cow herd.

Target weights

Heifers should be weighed every three months and checked against target weights relevant for the mature weight of the breed. Growth should be steady, not stepped with periods of little weight gain followed by rapid growth spurts. If heifers grow too fast before puberty, there is increased fat deposition in the udder tissue, lowering the future milk yield of the animal. It is important to look at the spread of weights as well as the average; well grown heifers should also have a minimal range in weight between the largest and smallest. 

Faster growth rate prior to puberty is associated with fat deposition and depresses subsequent milk yield. Maintaining sufficient body condition from first mating through to calving increases the chances of getting heifers pregnant during their first lactation. 

Rising plane of nutrition

From six weeks prior to joining, maiden heifers should be on a rising plane of nutrition with increased energy density in the diet and a balanced energy to protein ratio. For some farms, this can be achieved by feeding an appropriately formulated pellet. Including a live yeast supplement can help improve feed efficiency, enabling the heifers to get more energy from the diet. A proven product such as Yea-Sacc1026 can suit this purpose.

Mineral supplementation

Heifer growth involves the development of both muscle and bone, therefore a diet balanced in calcium, phosphorous and magnesium will promote healthy maturation. Sodium is important for ensuring good feed efficiency. 

Trace mineral supplementation is important for both fertility and immunity. Metabolic and infectious diseases after calving are associated with suppressed immunity and can cause heifers to leave the herd prematurely. If a heifer gets mastitis in the first few weeks after calving, damage to udder tissue can result in a costly loss of lifetime yield as well as the immediate costs of mastitis, so there is a considerable financial incentive to boosting immunity for first calving heifers. A proven organic trace mineral supplement such as Sel-Plex can be a wise investment. 

Nutrition and health

Feeding heifers well on good quality feed will reduce the risk of health issues. Heifers are more vulnerable than cows to mycotoxins, and therefore should not be given suspect forage. Where the risk of mycotoxins cannot be completely avoided, consider feeding a mycotoxin adsorbent. Heifers should be considered in any mycotoxin management program. 

Well-fed heifers will be more resistant to health challenges including parasites than those going through periods of under-feeding or those fed an unbalanced diet. Nutritional management of young heifers is a key area in dairy nutrition, as these heifers are ultimately the future success of the business. 

A leading dairy consultant nutritionist in New Zealand, Trish Lewis recently led a Dairy Advantage Workshop hosted by Alltech Australia for Australian dairy farmers and feedmills in Allansford. 

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