Variation in slaughter weights – does “topping” help?

Everyone suffers from a variation in slaughter weights to a greater or lesser extent, and one solution is to try “topping”, that is removing pigs to a spare pen or on to slaughter that look 5% to 10% ahead of the rest of their companions in a pen, writes John Gadd.

This is sometimes done about seven to 10 days before slaughter when the pens are beginning to look distinctly crowded. Overcrowding tends to slow up the growth of the whole pen, and can result in too much variation in slaughterweights.

As this practice seems to be a growing trend, I did some measurements in 2010 with co-operating farmers as I was unsure whether some forms of topping were a good idea. This was because in too many cases there were insufficient spare pens available to keep the selected pigs apart from those in other pens doing very well, and too much scrapping occurred.

Topping or “selective removal” is done for a variety of reasons. First, there’s removal to avoid overweights. This is essential, of course, in order to avoid a contract penalty, but those chosen must be loaded straight on to the transporter and not kept mixed in one holding pen overnight ready for the early-morning collection. Even this short period together would cause scrapping and stress.

 Second, some producers deliberately move some of the fastest-growing pigs to another pen seven to 10 days before estimated shipping date if they have suitable accommodation is available. Two UK producers I work with constructed straw bale pens with internal divisions for this purpose, and were careful not to mix growers from different pens together thus avoiding skin damage from scrapping and antagonistic stress offsetting growth rate. Topping adherents claim that the growth rate of the moved pigs improves by about 20g/day compared to not moving them, and those left behind improve by up to 50g/day thanks to the extra space and reduced competition for feed.

Third, there conventional topping, which is sending some of the fastest-growing pigs to slaughter about a week sooner than normal. These pigs are shipped within the contract weight range, but may be towards its lower end. Several of my Continental clients have tried this, and I checked their returns. Dependent on the terms of each farm’s contract, some 4.5kg of potential deadweight return was sacrificed, costing 6.5 euros/pig – say 13 euros for the two biggest pigs sent on early from each increasingly overcrowded pen of 15 pigs. The remaining 13 benefited from more room and better access to feed – even ad-lib feed – but they still saved only half a day occupancy from their faster growth, plus two euros-worth of food for the whole 13 pigs. And yes, you can add to this a week’s food saved from those shipped early, but this only recouped one-third of the 13 euros lost income per pen from the meat they would have put on during that final week.

This leads me to two conclusions. First, if you are forced into topping, keep an eye on the economic returns. The heavier you ship every pig as near to, but under, the contract overweight cut-off point, the better (my next blog will describe a useful method of achieving this). And second, on all of the farms, topping carried out sensibly and well did have the physical benefits as claimed by the protagonists, but it did not always pay.

This is a classic example that while published physical performance benefits may well be found in any research trial, when the econometrics are added in, then these favourable physical performances may need to be looked at anew in profit terms.

So, playing devil’s advocate, I’d have to say: 1, topping seems to work when the pigs were overstocked, but they shouldn’t have been in this position in the first place! Surely it’s cheaper not to overstock than to be forced into topping?

And 2, topping does work when there’s spare accommodation available, but again, maybe this should have been filled anyway!

Until I’m persuaded otherwise, have any of you got figures to change my mind? I’m afraid most of the the topping I see on my travels makes me nervous.

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About The Author

John Gadd, who has spent 60 years' involvement in pig production, has had more than 2,800 articles about pigs published and has written three best-selling pig textbooks. With hands-on experience that includes managing a grow-out herd at 1,800ft in Banffshire, Scotland, and 20 years in the allied industries with Boots' Farm Department, RHM Agriculture and Taymix, he set up his own international pig management consultancy in the mid 1980s and has now visited more than 3,000 pig units in 33 countries as a pig management adviser. (Photo courtesy Bournemouth Daily Echo)