Sow productivity has traditionally been defined as the number of pigs weaned per sow per year. Over the last 15 years, the use of improved genetic selection techniques has led to a large increase in total numbers born, which has made it possible to achieve 30 pigs per sow per year. However, in some breeding programs, heavy selection pressure for total numbers born has resulted in some negative implications for piglet quality, growth rate to market, feed efficiency and carcass value.

The Hypor Approach

Hypor’s approach to this dilemma is to focus on a combination of traits, to balance many aspects of sow productivity in a composite selection index in order to give the best economic outcome. The ability of a sow to wean large numbers of heavy piglets during her lifetime is central to this concept and is termed Weaning Capacity. This may be defined as 'The genetic potential to maximize the weight of piglets weaned and pork sold per sow productive lifetime'.

Hypor believes that Weaning Capacity is the best measure of reproductive performance because it defines the output of the sow as the weight of piglets weaned during the sow’s lifetime, which in turn determines the total amount of pork sold from her progeny. A sow that is capable of consistently producing large litters of quality piglets maximizes the potential of her progeny in the nursery and finishing phases resulting in faster growth, more efficient feed conversion, heavier market hogs and improved carcass quality. Furthermore, a regular flow of large, uniform piglets into the nursery maintains a consistent pig flow, which maximizes floorspace output and profitability.

The Genetic Perspective

From a genetic perspective, balancing all the factors that contribute to improved Weaning Capacity means selecting for a range of factors relating not only to litter size, but also for piglet quality parameters such as birthweight, numbers born alive and numbers weaned (Figure 1).

In addition, factors such as age at first mating and the interval from weaning to breeding also contribute to the number of piglets weaned per sow lifetime. Physical selection is an important component of Weaning Capacity potential and Hypor applies rigorous criteria for leg strength and conformation at its nucleus farms in order to maximize sow longevity. Similarly, rigid selection for number and quality of teats is a vital factor in determining milking ability, which contributes to rapid piglet growth and high weaning weights. .

Overall, the Weaning Capacity approach leads to sows that are capable of weaning large numbers of piglets without compromising birthweight, piglet survival at birth and up to weaning, mothering ability or sow longevity.

The Weaning Capacity Roadmap

While Weaning Capacity has many genetic components, there are also a wide range of environmental and management influences that contribute to realizing genetic potential. In order to understand how these factors influence Weaning Capacity, we need to break it down into its component parts and look at how each of them is optimized.

Figure 2, the Weaning Capacity Road Map, shows that the three basic components of Weaning Capacity are the number of pigs weaned per litter, weaning weight and litters per sow lifetime. Multiplying these numbers together gives the total weight of piglets weaned by the sow over her productive life. Numbers weaned per litter is a function of total numbers born, numbers born dead and pre-weaning mortality, while weaning weight is determined primarily by birthweight, lactation feed intake and sow and piglet health.

Sow longevity, or the number of litters per sow lifetime, is influenced by parity distribution, sow robustness, sow death loss and various aspects of management. Finally, management of the gilt up to the point of first weaning has a major influence on longevity, lifetime productivity and Weaning Capacity.

Maximizing Genetic Potential

A series of articles on Weaning Capacity will explore each of these topics in more detail and is aimed at helping Hypor customers maximize their Weaning Capacity potential. Each extra kilo (pound) of piglet weaned during a sow’s lifetime represents valuable, additional output, which reduces overhead costs per pig and increases margin.

Hypor females have the genetic potential to wean large numbers of heavy piglets and we believe that a realistic target for Weaning Capacity is 505 kg (1111 lb) of piglets weaned per sow lifetime:

12 pigs weaned/litter x 7.25 kg (15.98 lb)* x 5.8 litters per sow lifetime = 505 kg (1111 lb)

*Standardized 24-day weaning weight

This measure clearly defines the sow’s lifetime productivity and recognizes the value of piglet quality and sow longevity, not just litter size or pigs weaned per sow per year.

Weaning Capacity is the best measure of sow reproductive efficiency and profit potential of the breeding female, concludes Hypor.