"We do not give the gilt a long enough acclimatisation period from entry on to the premises to fully merging her with the herd," says Mr Gadd in his checklist for stimulating gradual and natural immunity in the breeding herd. Five weeks is the minimum length of time but six to seven weeks may be neccessary in order to combat some of the new viruses, such as PDNS, PMWS, PRRS, circovirus and coronavirus for example.

However, he continues, it can be costly to wait too long, so consult a local vet for a suitable minimal length of time. Speaking to the vet is advantageous as not only will he/she be monitoring the disease profile of the herd, they are also often knowledgeable about the prevalence of the viruses in your area and can also liaise with the vendor’s veterinarian if you are buying in replacements.

We are going about the challenge protocols in the acclimatisation period too casually, says Mr Gadd, often using the same old techniques such as afterbirth and fence–line culls etc. Instead, a specific planned and varied programme is needed as the pathogen population changes, including vaccination.

Once again, he recommends asking the veterinarian's advice you on what challenge procedures to adopt, for how long and when in the induction period. Normally, this will be in the first 14 days; the next month being a rest and recuperation period.

"We are growing gilts too fast between purchase or selection at 90 to 95kg and first service at 135kg," says Mr Gadd. This range is dependent on lean gain genotype. It is, therefore, advisable to slow them down in order for the immunity acquisition to catch up with the modern gilt’s precocity. This also allows the gilt’s hormone system to catch up with her ability to grow fast.

Mr Gadd recommends consulting a nutritionist about a gilt developer diet to grow them no more than 550g per day at 100kg, rising to 750g per day at eight and a half months old (135kg). Gilts grow very fast these days and a few take some holding back. This feed needs to be high in certain nutrients but fed under control.

To conclude, feed and manage the pregnant gilt and first-litter sow differently to your standard, established sows, says Mr Gadd. She is a totally different, developing animal, and quite apart from her nutritional needs, failure to do so could compromise her subsequent immune status.

February 2012