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13 September 2018

Benefits of hard feed post-weaning

Starch-based calf feed is recognised as beneficial to support rumen development pre-weaning, but is arguably equally important for the four to six weeks post-weaning off milk.

A good indicator that calves can be weaned off milk is when hard feed consumption is 1.0 to 1.5 kilograms per head per day (depending on the breed) for three consecutive days, provided weight targets have been achieved.If this hard feed intake is not maintained post-weaning, calves may suffer a double set-back. Fresh pasture is a bulky feed, so continuing and even lifting supplementary feeding after  weaning off milk can reducethe risk of growth rates melting away from full but not fully-fed youngsters. A 75 kilogram calf, growing at around 0.7 kilograms per day needs close to 25 mega joules of metabolisable energy per day, provided it is not cold and wet, and expending energy to keep warm.

If your calves are receiving, for example 600 grams of NRM Calf Milk Replacer as a liquid feed, they would be getting close to 50 percent of their daily energy requirements from readily digestible milk powder that is directed straight into the abomasum and has no effect on rumen function. Making up this energy deficit would necessitate harvesting and digesting about another kilogram of dry matter of high quality pasture (five to eight kilograms at fresh weight). This is quite difficult for a relatively immature rumen at a time  when forage intakes are typically modest. Managing pasture quality with calves alone can be hard, especially during November when pasture fibre levels can rise and protein falls. 

Although straights, such as PKE and barley, can help to fill a simple feed deficit for older calves, higher quality, nutritionally balanced feeds are more suitable for younger calves. Whilst energy is typically the first limiting factor for growth, protein is important for frame and muscle development; and may even determine the extent to which calves can express their genetic potential later in life.Extended demand for 20 percent protein calf feeds like GrowUp 20% rather than 16 percent options indicates that more farmers have decided that the extra investment in a higher protein feed is worthwhile.

Coccidia challenge is most likely to be highest in the eight weeks following weaning, so a hard feed that contains a coccidiostat makes sense. Calves take time to build up resistance to coccidiosis and may be at a greater risk of infection when grazing nursery paddocks in which the parasite load can increase over the years. A fully balanced hard feed also delivers major minerals, trace elements and vitamins that may be lacking in pasture. Whilst mature cows can benefit from the vitamin production of a fully functioning rumen, it is likely that the rumen of recently weaned calf is not capable of producing essential B vitamins, particularly if anything about the pasture diet is sub-optimal. 

To discuss your hard feed options post-weaning, contact your local PGG Wrightson Technical  Field Representative.

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