Beef cow nutrition
Once the cows have calved there are 3 key objectives:
- Achieve at least 1.0 kg/day LW gain in the calves.
- Feed the cow to achieve a body condition score (BCS) of 3.0 (out of 5) at mating in order to optimise mating performance (Friesian-cross beef cows BCS 2.75).
- Prevent metabolic issues.
In Friesian-cross cows, it may be necessary to limit feed intake for the first 3-4 weeks in those cows rearing a single calf so that udder problems do not result from over-production and under-suckling.
A sward height of 6cm is sufficient for Hereford x Friesian heifers during the first month of lactation, increasing to 12cm sward height during the 2nd month of lactation. With this level of feeding, calves should gain at least 1kg/day while suckling their dams.
By the time a calf gets to 3 months of age, grass makes up 50% of the dietary intake.
In order to achieve growth rates in excess of 1kgLW/day, the calf's pasture intake needs to be 4kgDM/day in the late spring when feed quality is highest.
Cows will to some degree buffer their calves when under-fed in early lactation by losing liveweight to maintain milk production. However, remember that the total amount of milk that a cow will produce is driven by how high her milk production is at the peak of lactation. Therefore if the cows are not allocated enough feed in early spring, they will not achieve their maximum peak lactational height. Peak lactation also happens to coincide with mating time. Maximising their milk production at this time will also maximise their conception rates which is vital for maximising your profit in a beef cow herd.
Therefore in late spring, cows need to be eating in excess of 12kgDM/day. The better a cow is fed, the less time it will take for her to reach first oestrus after calving. Conception rates will always be higher in individual cows that have had at least one oestrus prior to mating. Those cows consuming up to 20kgDM/day pre-mating, should be near a BCS of 3.0 by mating (target).
On the whole, metabolic issues like milk fever and grass staggers can be prevented through good nutrition. By giving cows an ad lib pasture allowance of 2500kgDM/ha (6-7cm sward height), maximum intake can be achieved. However, Friesian x Hereford cows for example, may need some form of magnesium either in the feed or water. This is best started 3 weeks before calving and continued for at least a month into lactation where practical.
