Among the economically important traits for swine production systems, the number and quality of piglets weaned per litter and growth of the market pigs have a high priority. Among the factors that influence these traits is birth weight (BW) of the piglet, which measures growth from conception to the end of pregnancy. Two paths that the Choice genetic program uses to improve these traits is to select for optimal birth weight and litter uniformity.
It is well known that selecting for increased litter size in hyper-prolific maternal lines leads to lower average birth weights, with a higher proportion of piglets under 1 kg, which in turn increases piglet mortality, especially in the first week of life.
Research has shown a clear relationship between piglet birth weight and mortality. Piglets with a birth weight of less than 1 kg (2.2 lb) have only a 78 – 79% chance of preweaning survival. Piglets weighing at least 1.3 kg (2.86 lb) at birth have a 90 – 91% chance of survival to weaning for our M3 Large-White and M6 Landrace lines. However, selection for birth weight is complicated by the fact that piglets with very high birth weights also have a higher risk of mortality.
Choice Genetics is committed to producing large litters of excellent quality piglets. Therefore, our selection program is designed to not only have high numbers of piglets born alive, but also high quality viable piglets and uniform litters.
Piglets with good birth weights grow faster throughout their lives than smaller litter mates. So piglets with good birth weight not only have a better chance of survival but also grow faster in the nursery and finisher stages, resulting in more animals which achieve the top market grade.
Piglet size and quality are also important for the multiplier. Decreasing piglet mortality increases efficiency because more high quality replacement gilts are produced. Birth weight not only affects growth, development and fattening, but also the reproductive capacity of females. Over their entire productive life, gilts with a birth weight of less than 1 kg (2.2 lbs) of birth weight will produce 2.7 fewer piglets on average than their counterparts weighing 1 kg or more. Choice’s ongoing genetic improvement program has produced a parent female of exceptional maternal ability, the CG36. This F1 parent sow has the ability to produce litters with individual piglet weights of 1.35 kg on average, with only 4% of the piglets born weighing less than 1 kg, resulting in weaning large litters of heavy, uniform piglets.
| Number of litters | 315 |
| Total number of piglets born alive | 4728 |
| Average number of piglets born alive per litter | 15.01 |
| Average birth weight (pounds) | 2.2 |
| Average litter weight (pounds) | 44.09 |
Because Choice is aware of the importance of birth weight and uniformity, we monitor them closely in our genetic nucleus herds and include them in our maternal indexes, with the objective of maximizing the reproductive performance of our client’s herds.
