Management of commercial swine breeding herds involves a thorough understanding of reproductive physiology, genetics, nutrition, immunology, disease control, environment, and other factors. Modern swine operations might use site-segregated production systems, with separate sites for semen production, breed-to-wean sow farms, and wean-finish, nursery, or grow-finish farms. Alternatively, they might have farrow-to-finish facilities all on a single site. High health and biosecurity are the goals for all production systems, and the closed-herd concept, which emphasizes preventive medicine strategies along with herd protection, minimizes the risk of disease loss when combined with intensive management, sound nutrition, and genetic selection.
Pearls & Pitfalls
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Measures of Reproductive Performance in Swine Relative to Industry Averagesa
----------Industry Data---------- | ||||
|---|---|---|---|---|
Measure | Explanation | Below Average | Average | Above Average |
Weaned sows bred by 7 days (%) | Percentage of sows bred within 7 days after weaning | < 84% | 85–90% | 91–95% |
Wean-to-service interval (days) | Days from wean to first service (can be extended in summer and autumn and by parity-1 sows) | ≥ 7–10 days | > 6.0–6.9 days | 4.5–6.0 days |
Repeat services (%) | Percentage of sows reserviced within a wean group | ≥ 9.0–14% | 5.1–8.9% | 2–5% |
Multiple matings (%) | Percentage of sows receiving multiple matings (will be lower in single-service timed artificial insemination programs and can change with wean-to-service interval) | ≤ 88% | 90–94% | 95–99% |
Regular returns to service, 18–24 days (%) | Sows with a regular return to estrus (18–24 days) | ≥ 9–13% | 5–7% | 1–4% |
Irregular returns to service, 25–37 days (%) | Sows with an irregular return to estrus (25–37 days) | > 5% | 2–3% | < 2% |
Abortions (%) | Percentage of pregnant sows that abort | > 3% | 1.5–3.0% | < 1.5% |
Not in pig (%) | Percentage of sows that reach full term, presumed pregnant, but do not farrow | ≥ 2.1% | 1–2% | 0.5–0.99% |
Day 30 conception rate (%) | Sows bred diagnosed pregnant by use of ultrasonography | < 85% | 88–92% | > 92% |
Farrowing rate (%) | Percentage of sows mated that farrow | < 82% | 83–87% | 88–95% |
Total pigs born/litter | Total number of pigs born per litter farrowed | < 13.5 | 13.9–14.9 | 15.0–16.0 |
Live pigs born/litter | Number of live-born pigs per litter farrowed | ≤ 12.6 | 12.9–13.9 | 14.0–15.0 |
Stillbirths (%) | Percentage of total pigs born that are stillborn (changes with litter size) | ≥ 8.0% | 6.0–7.8% | < 4.0–5.99% |
Number of stillborn pigs per litter | Number of stillborn pigs per sows farrowed | ≥ 1.2–1.5 | 0.91–1.1 | 0.5–0.90 |
Mummified fetuses (%) | Percentage of total born pigs that are mummified (can increase as total born litter size increases) | ≥ 3.0–4.5% | 1.0–2.99% | ≤ 0.7–0.9% |
Number of mummified fetuses per litter | Number of mummified fetuses per sow farrowed | ≥ 0.5–0.6 | 0.3–0.4 | 0.1–0.2 |
Pigs weaned per sow farrowed | By calculation; measures can change if including nurse sows | ≤ 9.8–10.8 | 11.0–11.5 | ≥ 11.6–12.2 |
Nonproductive sow days range | Measure will increase if data includes days from gilt entry until service | > 56–74 days | 42–50 days | ≤ 30–38 days |
Replacement rate (%) | 39–50% | 52–59% | 62–73% | |
Culling rate (%) | 26–37% | 40–47% | 51–65% | |
Sow death (%) | Includes sows that die or are euthanized | ≥ 13.5–16.8% | 10.4–12.4% | 6.7–9.4% |
Weaning age range (days) | Excludes nurse sows | 17.5–19.5 days | 20.1–20.9 days | 21.3–23.1 days |
Gestation length (days) | Can change by use of induction of farrowing | < 114.5 or > 116.5 days | 115.9 days | 116.0 days |
a Values are according to breeding-herd record summaries from 2019 and include data from approximately 1,500 farms; the average herd size was > 2,000 sows, representing fertility data for > 2.5 million sows. Reference sources: MetaFarms, Production Index Analysis 2019; Swine Management Services, LLC; PigCHAMP, 2019 Benchmarking Summaries, USA. | ||||
The breeding program should be evaluated at specified intervals to ensure that progress in both efficiency and productivity is being made. Several efficiency/production parameters to review when analyzing herd reproductive performance are shown in the table . The postweaning performance of a breeding herd's offspring can be measured through assessment of such parameters as feed-conversion ratio, average daily gain, total days to market, and postweaning death loss.
Reproductive problems on a swine farm can have a single cause or result from a combination of genetic, nutritional, environmental, health, and management factors. When investigating a herd fertility problem, the practitioner should remain focused on herd measures and not on individual animals.
Accurate, up-to-date records and realistic expectations for the herd genetics and production system are essential when investigating a breeding herd problem. A certain percentage of “abnormal” animals and/or reproductive problems are common in all herds and should be expected.
