Beef and Sheep Notes June 2009

Herd fertility problems in the form of late calvers, barren cows and high replacement rates are a major cause of low profitability in suckler herds.  The success or failure of next year’s calving will be determined by this year’s bulling period.

Ideally cows should be on a rising plane of nutrition at bulling to maximise conception rate and this will require careful grassland management due to this year’s pattern of grass growth.  Some fields have very high covers as they were not able to be grazed due to poor ground conditions.  Sward quality will suffer for a considerable period if these covers are not brought under control. Consider topping, closing for silage or block grazing where ground conditions permit.

In a herd where there are two or three calving seasons or indeed all year round calving, it is easy for a cow to “slip” from one calving season to the next (that is, calving interval more than 365 days) without being noticed.  In a batch calving herd it is much easier to identify cows that have not produced a calf within a fixed time period.  Routine management, vaccinations, grazing management, batch weaning and selling etc are all so much simpler when calves are of a similar age.  A 12 week calving period should be more than adequate for most suckler herds. Consider putting heifers to the bull two to three weeks before the main cow herd.  This allows more attention to be devoted to this important group at calving time and allows an extra cycle for them to get back in calf.

If there has been a problem with repeats or infertility in the past, then it is worthwhile asking your vet to do a blood profile to check mineral status. Phosphorus, Copper and Iodine levels can all affect fertility performance.

Although most discussion centres on cow fertility performance, the bull usually warrants more attention than he receives.  Pay attention to EBVs when purchasing – make sure he has the genetics to do what you bought him for!  Don’t implement a sudden change from ad-lib feeding to starvation and over-work and expect a high pregnancy rate.  Pay attention to feet and legs and have any remedial work done well in advance of the mating period.  It is worthwhile noting that a small percentage of bulls are completely infertile but up to 30 percent may be permanently or temporarily sub-fertile so have your vet perform a breeding soundness examination before the bulling period.  Rotate bulls and/or pregnancy diagnose early so that an infertile or sub-fertile bull can be identified early.  

Generally, calves will encounter the first worms, especially lung worms, during June and into July. If any calf is seen coughing, and this will happen from mid-June onwards, it is advisable to inject all calves with an ivermectin type product. This will eliminate both lung worms and stomach worms and will have up to five weeks residual effect. At least one other dose is recommended into the autumn. Keeping the calves clear of worms helps their immune system against respiratory diseases.

After a cold wet spring, has lamb growth rate suffered? Low growth rates result in lambs retained on farm longer, putting further pressure on grass supply. Target growth rates are 300g/day up to weaning and 250g/day post weaning with the target weaning weight for a twin lamb 32KG. Feeding concentrates should not be a substitute for maximising performance at grass. Creep grazing lambs ahead of ewes can improve growth rates to a similar level supplied by concentrates.

Where grass is in short supply, feeding concentrates will maintain growth rates on target for finishing, with 10KG – 14KG of concentrate required to achieve 1 KG carcase weight, depending on lamb breed and genetics. With concentrates at £230/tonne, it costs between £2.30/KG - £3.22/KG of meal feeding to achieve 1KG lamb carcase. If lamb price remain above £3.50KG, then feeding concentrates is a viable option.