A most common question is 'what is the value of extra weaning weight?' Say, a supplier comes knocking on your door with the next additive for the lactating sow feed. It costs 20 euros per kilogram (huge gasp goes here!) and you need one such kilogram per metric tonne of feed. This will give you an extra 500 grams on your current weaning weight, which at 21 days of age is lamentably too low, at 5.5 kg per piglet (summer and all that, you know).
So, we assume the sow consumes a (hugely optimistic) 6 kg feed per day for 21 days, which is 6 grams per day of the said additive, for a total of 6x21=126 grams per lactation period, at a cost of 0.126x20=2.52 euros per sow per litter. Not an insignificant amount of money!
Now, let’s assume your pigs at weaning are indeed 500 grams heavier, just because of this new additive! How do we evaluate the return on investment? Indeed, there are many good ways that have to do with heavier weight at the exit of the nursery phase, lower mortality, better feed efficiency, reduced veterinary expenses, and so on...But, these calculations will have to wait until pigs are 20-25 kg body weight and these are still indexes, with little monetary value. We need an answer now!
What I find as most ‘acceptable’ by my customers is using the cost of piglet feed it would take to get these extra 500 grams post-weaning. Say, a super quality piglet feed costs 0.8 euros per kilogram (perhaps, not so super quality, but that’s what we have now). Assuming a 1:1 feed efficiency rate (I know, this is not entirely correct, but it is practical) we need 500 grams of this piglet feed to get those extra 500 grams of body weight. So, each piglet would need 0.4 euros of extra expense just for feed. Assuming the sow had a litter of 10 piglets, this makes the expense for extra feed equal to 4 euros per sow. Now, this is worst than the 2.52 we spent on the additive, so in this case the additive wins!
Now, this sow required 2.52 euros to spare us these 4 hypothetical euros, so we’re talking a return on investment of 4:2.52 = 1.58, which means for every euro spent on that additive, the farmer gets back his euro and on top of that (or it would make little sense to just swap euros around!) at least an additional 1.58 euros are deducted from the feed bill. Adding the extra benefits described above only make things better!
But, before you spend the 2.52 euros per sow, better make sure the additive really works!