Sheep farming

TURNING POOR PERFORMANCE INTO LONG TERM GAIN: WEIGHING LAMBS

If you think ahead for a minute to the time when most of this year's lamb crop will have been sold, what are the chances that you'll have a small but embarrassing group of stragglers that refuse to reach saleable condition? This is a question that independent sheep specialist Lesley Stubbings OBE would like all sheep producers to ask themselves1.

No stragglers-Lesley

"When you get chatting to farmers about a 'no stragglers' policy, the penny drops immediately," she suggests. "Stragglers symbolise failure to farmers who strive to produce finished lambs they're proud of.

"Yet too many flocks reach a point when most lambs have been sold, leaving a final, nuisance group. These are poor doers, which you give extra feed and still don't grow well and, frankly, are a costly embarrassment."

To begin addressing this problem, Lesley has introduced the practice of weighing lambs at eight-weeks old on a number of farms. Even on those without weighing equipment, she has seen a simple homespun method work well. "All this requires are a set of bathroom scales and couple of helpers," she explains. "Weigh yourself, then get your assistants to catch a few lambs, bring them to you, then weigh yourself again while holding a lamb under each arm.

"It doesn't take long to do ten percent of a group, then work out the average weight."

This eight-week weight approach is endorsed by AHDB Beef & Lamb in their Better Returns Programme Manual 5, 'Growing and finishing lambs for better returns'. It suggests that growth rates from birth to eight-weeks should be higher than 250g/day. So a 4kg lamb at birth should weigh at least 18kg at eight-weeks (56 days x 250g = 14kg + 4kg = 18kg). At 300g/day growth, lambs will be 21kg.

There are three essential factors, explains Lesley Stubbings, to hitting this eight-week target: "Optimum ewe body condition at lambing, pasture quality and internal parasite control. The critical thing to realise is that lost growth before eight-weeks of age is gone forever - catch up is simply not possible."

Of course, monitoring growth rates beyond eight-weeks is a logical progression, where decent handling and weighing systems come into their own. Lesley advises that 300g/day from birth to finish should be possible without creep feed.

In addition to eliminating the poor performing group, achieving good growth rates and optimum timing of sale across the entire lamb crop has other advantages:

  • Earlier sale means earlier payment.
  • Good timing avoids penalties for over/under weight or over/under fat class.
  • When lambs go, grazing is released for ewes, helping get them into optimum body condition for mating, which itself is linked with higher conception rates and lamb numbers next time.
  • Good body condition maintained from mating to lambing helps achieve optimum milk production and lamb growth rates during the critical birth to eight weeks period.

Quite how much this virtuous cycle is worth financially is impossible to quantify as a single figure that applies to all flocks. But sheep farmers are well capable of judging for themselves what the list above could be worth to them.

Meanwhile, as recently as April this year, an article in Farmers Guardian suggested that nearly half of finished lambs failed to meet the target specification required by processors2. Of those out-of-spec lambs, about half were too fat and the other half, poor conformation.

In a year like this when a large lamb crop is likely to see more finished lambs than usual chasing a buyer, Lesley suggests that consistently hitting buyers' specifications and eliminating stragglers will be essential aspects of flock performance management.

Mid-season Knockout Drench 'could help boost lamb growth rates'

Still on the theme of a larger than usual lamb crop chasing buyers this year, Lesley suggests that a one-off Knockout Drench for lambs about a month post-weaning could help boost growth rates during the second half of summer.

"Exploiting the full efficacy of group four or five wormers, it can reset to zero the worms that may have survived earlier treatments, creating improved growth rates as a result," she explains.

No stragglers-graphic

In addition to this, according to Zoetis vet Dave Armstrong, there is also a possible longer term gain to be had. "Modelling studies indicate that development of resistance to group one, two or three wormers – BZs, LVs and MLs respectively – may be delayed by strategic use of dual actives in this knockout protocol," he says3,4.

1. Lesley Stubbings, March 2016. Personal communication.
2. Farmers Guardian, 29 April 2016. How best to market your sheep. P31.
3. NZ Vet J. 2009 Aug; 57(4): 203-7. doi: 10.1080/00480169.2009.36902
4. Bartram et al, Veterinary Parasitology 186 (2012) 151– 158
for further information, please see the product SPC, or contact your veterinary surgeon, SQP or Zoetis UK Ltd, Walton Oaks, Dorking Road, Walton on the Hill, Tadworth, Surrey, KT20 7NS. Customer Support 0845 3008034. www.zoetis.co.uk. Always seek the advice of your medicines provider. Use medicines responsibly (www.noah.co.uk/responsible).

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