Customised Genetics - A Case History

With processors’ specifications becoming more and more specialized, US-based Andrew Coates, PIC’s Technical Services Director for Genetics, describes how a custom selection index can be designed to deliver to the most exacting contracts.

5 December 2005

5 minute read

The scenario

The phone rings and you answer it. The buyer of your pigs wants to set an appointment to agree your contract for next year. The good news is they are changing their payment contract but the bad news is that your pigs are too light, too fat and not enough eye muscle depth for their new requirements. Sounds familiar?

At the meeting, more specific details are provided: carcass weight needs to increase by 4-5kg; backfat needs to be lower by 3mm; and eye muscle depth should increase by 5mm. He warns that you have six months to make some improvement, and the other six months on your first new contract to continue those improvements.

This was a real-live wake-up call for a US customer a few years ago. How could PIC help him? The production system consisted of nearly 15,000 sows in total, spread over several herds varying in size from 600 – 2400 sows and nearly all were farrow-to-finish.

Short-term change – PIC’s nutrition services team performed an audit of the feed system from manufacture in the home-mill, diet formulation, analysis of complete feeds, feeding mechanisms and pig consumption. The first priority was to achieve greater consistency of diets produced in the several feed-mills, plus consistency of the diets provided at the different stages of growth. Changes were made to diet formulations to accelerate lean growth to produce heavier and leaner pigs.

Medium-term change – PIC’s genetic services team carried out an audit of the male and female products being used by the customer. They found that through the ups and downs of profitability there was a wide variety of terminal sires still being used.

Figure 1. The relative weightings of each trait in the tailored selection index.

These were a combination of natural service and AI through on-farm semen collections and processing in the different sow farms. There was little consistency in the boar product being used and the average age of boars was high on several farms. All were contributing to the inferior lean content.

The bold decision was taken to move to a central boar stud for all terminal sire needs; by removing all on-farm AI ‘labs’ and the majority of old boars (leaving only heat detection males). The PIC337 was chosen as the terminal sire for all farms, to improve the potential for sustained lean growth to heavy weights. The quality of boars continued to improve with each new delivery of boars (Table 1).

PIC’s genetic services team designed a custom selection index that emphasized low backfat and high eye-muscle depth. The index included the effects of several gene markers, like PT1 for lower backfat. (Figure 1). The index was applied to the boars then in the stud inventory and to all subsequent replacement boars. Under an agreement with the stud, these boars were custom-housed and semen collected and processed for delivery to the customer.

Long-term change - Similarly with the sow herd, the average age of many females was high with replacement gilts often having been derived from the terminal generation. Longer term improvements were planned by reducing the substantial genetic lag in their gilt multiplication system. GP males were turned over and new boars were also ranked on the custom index. The replacement of older GP sows and those of the ‘wrong’ breed composition was also stepped up through the introduction of new GP females.

The Results

Initially, over the first four months average carcass weight was increased by 2-3kg (see Figure 2), without serious increases in backfat. A further 2-3kg was also added over the next six months. After the first 4-5 months, backfat began to decrease and loin depth to increase (Figures 3 & 4). Trends that were sustained more or less over the next two years, as steps were implemented and their effects reached the market pigs.

The process that this company went through shows that change is not immediate. Nevertheless, significant changes to the traits of core commercial importance can be made in a relatively short time-frame. It is vital to consider a multi-faceted approach – a combination of understanding the on-farm performance; tailoring the genetics; realising that there are bold decisions to be taken; and seeing through the implementation of a new farm strategy with the unit staff.