Tradition & Innovation
It is worth remembering that all traditions began with innovation and the relationship between these two is an essential part of the identity of each new generation. In pig production a tradition handed down from generation to generation is the belief that the value of the cull sow should pay (as near as possible) for the replacement gilt. Here, briefly, are some figures that come from innovative thinking based on fact.
Based on the BPEX 'All Farms' average performance figures for YTD June 2014 I have calculated that the average cost of a production cycle for a gilt through to parity 4 that includes the writing off of the cost differential between the 'home produced' gilt and the cull sow over 4 parities (UK average culling age) is £425.59 or £2.63/day against a production index of 161.5 days. The cost of the parity 5+ production cycle is £406.44.
Gilts and sows that incur return(s) in their lifetime or the odd low born alive litters (BA/lit) or a combination of both are retained within the herd on the basis that it more expensive to replace them.
The cost of each piglet born alive to a gilt recording 6 BA/lit is £70.93 as opposed to the national average £35.38 for a litter of 11.92. If this animal then goes on to record a 21 day return as a parity 2 sow, three litters of 11.92 BA/lit including a further 35 day return in parity 4 and a litter of 5* BA/lit in parity 5 (*statistics suggest that she will) then the lifetime difference in the cost of her piglets against an animal that performs at average 11.92 with no returns to 5 parities is 12.95/piglet or an additional cost of £605.54 against her output.
Some producers, persevering with a gilt because it is too expensive to replace her will record at least 3 consecutive returns these would increase her first production cycle cost by £165.69 making her piglets (11.92 BA/lit) cost £49.60/piglet. A gilt that has a litter of 3 born alive equates to a per piglet cost of £141.86. The cheapest time to replace a gilt is at the point of failure.