Pig Reproduction
Farrowing rate in this paper is described as the percentage of females that farrow per group of contemporary females bred. The components used to calculate farrowing rate are given in the following equation: Farrowing rate = [total number of sows bred for a specific group (number of mated females returning to estrus at a regular interval + number of mated females returning to estrus at an irregular interval + number of mated female that died during gestation + number of pregnant females that were intentionally or unintentionally culled + number of pregnant females that were deliberately aborted due to over breeding)] divided by total number of sows bred from a specific group.
A competitive target in the United States is a 90 percent annual farrowing rate. Data from PigCHAMP shows 838 farms had an average farrowing rate of 76.1 percent in 1999.
Boar fertility can affect farrowing rate, however, semen quality may have more of an effect on litter size.
Farrowing rate seems to be lowest for gilts and parity 9 and 10 sows, compared to farrowing rate of sows serviced in parities 2, 3, 4 and 5.
Productivity increases as lactation length decreases, but lactation length can affect reproductive performance of individual sows.
Repeat breeders, or sows returning to service any time during gestation, can have an effect on farrowing rate.
Housing can also influence the percentage rate. Two reports by PIC show sows housed in single stall had a 0.5 to 3.0 percent advantage in farrowing rate vs. sows housed in groups.
Estrus detection needs to be highly accurate since insemination late in the cycle will lower farrowing rate.
Recommendations to mate sows only once would make it highly unlikely a 90 percent farrowing rate would be achieved.
Semen handling will also affect rate. Liquid semen must be stored at a temperature between 16 to 18 C.
Labor has a large impact on reproductive performance. A North Carolina State University study showed a difference in farrowing rate of 16 percent and 3.5 pigs per litter between the most skilled and least skilled technician inseminating the same number of sows.
All these factors lead to the following Top 10 Rules for a 90 percent farrowing rate.
Top
10 rules for a 90% farrowing rate
Use highly skilled, knowledgeable and motivated workers for estrus detection, AI, supervising natural matings and and managing dose of semen.
Do an excellent job of detecting estrus at lest once per day, preferably during early morning hours.
Use excellent quality semen for AI and highly fertile boars for natural mating.
Do an excellent job of managing stored doses of semen.
Do an excellent job of feeding sows during lactation, especially the first 7 to 10 days to reduce weaning-to-service interval.
Identify and cull problem breeders to avoid lowering farrowing rate.
Prevent stress during the first 28 days of gestation - heat stress, social stress - to reduce partial or total loss of embryos
Grow, develop and manage replacement gilts with excellent body condition when mated between 200 to 250 days of age.
If fertility of boars is unknown, use heterospermic semen or mate sows to two different boars during the same estrus..
Prevent reproductive diseases.