I’ve been monitoring growth rates of batches of pre- and post-weaned pigs on UK units, writes Maisie Lord. Diving into the detail has raised some eyebrows when it comes to daily weight gain, post-weaning. Those heavier piglets at weaning have not necessarily recorded the best post-weaning growth rates, while the lower achievers at the weaning goal post have come up trumps.
We’re not suggesting that heavier weaning weights don’t carry through with an advantage. A 0.5kg advantage at weaning is well documented to be worth five times – or 2.5kg – more by slaughter.
So it was of little surprise that the recent trial work confirmed that, even in the snapshot period of four weeks after weaning, those weaned at heavier weights weighed more after a further four weeks when the same diets were fed to all pigs.
But things got more interesting when we looked at growth rates post-weaning. To give an example from recent trial work: piglets weaned almost 1.5kg lighter than their counterparts grew, on average, 50g more in the first nine days post- weaning, while being fed the same diets. In another trial, two groups of piglets were weaned at comparable start weights (40g difference between them on average) into the same building and offered the same starter feed: by day 19 post-weaning, one group had gained 400g more.
We are well aware that pre-starter intakes drive post-weaning growth and it might be that individuals who relied mainly on mum’s milk and less on pre-starter feed didn’t wander far to get their fill, compared with their litter mates who relied, to varying degrees, on pre-starter feed to supplement the available milk supply.
Cargill research shows that 44% of variance in gain during the nursery period can be explained by a difference in total pre-starter intake pre-weaning. On average, just over 50% of this pre-starter feed is eaten between day 21 and day 28 pre- weaning. The difference between weaning at 24 days and 28 days old can, therefore, easily be 150g in total of pre-weaning feed intake, while between 21 and 28 days, the difference can be upwards of 250g.
If you consider that the difference of 100g of intake pre-weaning can drive up to 50g/day of growth in the immediate post-weaning phase, this starts to add up in total kilos gained.
So ‘little and often’ and ‘the earlier the better’ may well be a very worn out drum for indoor producers, but when we consider the difference pre-weaning feed intake can make post-weaning, it is one worth continuing to beat.
Maisie Lord is a pig nutritionist for Cargill. Based in North Yorkshire, she worked at Cargill’s innovation centre in the Netherlands before joining the UK team.