Keeping Heifer Growth on Track at Grass

Close attention is paid to grassland management and having the grass at the correct stage for grazing the milking herd. The same should apply for dairy heifers to achieve optimum growth rates.

Heifers are often left to graze the poorer fields or tidy up after the milking cows and if grass is not at the 3 leaf stage for grazing, quality is compromised.

 

Dry matter intake is the main limiting factor at grass, with heifers over 300kg on quality grazing being able to achieve up to 1kg growth/day without supplementary feeding, but younger heifers may struggle to achieve the target growth rate of 0.75kg/day. Weigh heifers at turnout and then a month later to see what growth they have achieved. Smaller heifers or those with poorer growth rates could be separated and fed concentrates to improve performance.

 

In spring, grass contains significantly more protein than required so any supplementary feed should be low protein and fibrous in nature. Grass may contain 20% protein or even more but young heifers generally require 14-16% protein depending on growth stage and around 12% for in-calf heifers. Level of supplementation will depend on grass quality and quantity but in the region of 1-2kg/head/day is appropriate.

 

Don’t forget minerals! Although deficiencies may not be immediately apparent, supplementation has been shown to improve growth rates by 10-20%. Longer-term, minerals will support better health, immunity and conception rates. Be aware of the lungworm risk and if heifers have not been exposed before, vaccination in the spring is a must.

 

A significant increase in rearing costs can result if target growth rates are not achieved at grass. Delayed service past 15 months means that 24 month calving is not achieved, and lifetime performance, milk yield and fertility is compromised. Remember, heifers must be between 55-60% of mature body weight for service at 13 to 14 months, which is around 360kg, assuming 650kg mature liveweight. This is equivalent to a wither height of 125cm for Holstein-Friesians.

 

Weight for Age Targets for Dairy Heifers

 

Age

% of Mature Weight

Liveweight kgs

Birth

-

40

8 weeks

12

80

6 months

30

195

 9 months

40

260

13-14 months (mating)

55-60

357-390

Pre-calving

90

585

Post-calving

85

550

2nd calving

92

598

 

Based on Holstein-Friesian’s with mature body weight of 650kg (adapted from AHDB Dairy)

 

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