Key Productive Parameters in Swine Production.

ANIMAL PRODUCTION

7/2/20257 min read

Introduction

Modern pig farming relies on the continuous measurement of key indicators to identify issues and optimize profitability. The computerization of farms allows for daily monitoring of the operation's status and a thorough analysis of "bottlenecks" affecting productivity (1). Measuring and controlling reproductive, growth, and efficiency parameters (among others) is essential for making timely decisions and improving overall performance.

Key Indicators in Swine Production

Below are the main productive parameters in an intensive pig farm:

Prolificacy (number of piglets per litter): This is the average number of total piglets born (live + dead + mummified) per farrowing (2). In modern sows (hyper-prolific hybrid lines), around 14–18 total piglets per litter are achieved (3). On average, gilts wean 12–15 live piglets, and multiparous sows wean 14–18 (4). (In contrast, traditional breeds like the Iberian pig typically have only 5–7 live piglets per farrowing) (2). Prolificacy reflects the sow's fertility and fetal/neonatal survival, and is calculated as: Prolificacy = Number of total piglets born / Number of sows farrowed.
Farrowing rate: This is the percentage of sows that farrow relative to the number of matings performed (5). It's the proportion of gestating females that actually farrow. In technologically advanced farms, the farrowing rate is usually close to 85–90%, meaning about 3–4 percentage points below the gestation rate (6). For example, with 90% fertility ("get pregnant"), the farrowing rate would be 86–87% (6, 7). This indicator evaluates reproductive success: a low rate suggests fertility, health, or management problems during gestation.
Wean-to-estrus interval (WEI): This is the number of days between a sow's weaning and her next estrus or service (8). Ideally, after weaning a litter (21–28 days of lactation), the sow should come into heat in approximately 4–7 days. A short WEI (5-7 days) maximizes the number of farrowings per sow per year. Prolonged values (e.g., >10–12 days) indicate "anoestrous sows" that don't return to estrus quickly, which lengthens unproductive periods. An efficient manager aims for a WEI of less than one week (8).
Average Daily Gain (ADG): This is the amount of weight a piglet or pig gains per day (kg/day) during a productive phase (9). It's calculated by dividing the total weight gain by the number of days elapsed. For example, a piglet that grows from 6 kg to 30 kg in 49 days has an ADG of 24/49 ≈0.49 kg/day (9). In a technified system, weaned piglets are expected to achieve weight gains of 0.5–0.7 kg/day in the nursery phase, and finishing pigs should exceed 0.8 kg/day (up to 0.9–1.0 kg/day in elite genetics). Lower values reflect problems with feeding, health, or management (stress, group order, feed quality, etc.).
Feed Conversion Ratio (FCR): An index that relates feed consumed to pig weight gain (10). In other words, it indicates how many kilograms of feed are required to produce 1 kg of live weight. For example, an FCR of 2.2 means that for every 2.2 kg of feed consumed, the animal gains 1 kg of weight. Since feed is the highest cost input, FCR is a key indicator of economic efficiency. Thanks to genetic, nutritional, and facility improvements, modern intensive farms achieve FCRs close to 2.1–2.3 (11). (In the 1990s, values around ~3.1 were acceptable (11); today, 2.2–2.3 is standard in finishing, and <2.2 is excellent).
Pre- and Post-weaning Mortality: These represent the percentages of piglets that die before and after weaning, respectively. Pre-weaning mortality (for weaning at 21–28 days, includes neonatal deaths) typically ranges between 10% and 20% in hyper-prolific pigs (12). Many vulnerable piglets die within the first 72 hours after farrowing (12). The goal is to minimize it (<15%) through careful management of births, heat, and colostrum. Post-weaning mortality (in the first 2–3 months of finishing) should ideally be very low (<2%). In efficient operations, a range of ~1–2% is considered normal; values >2% indicate health or management problems (hygiene, feeding, stress) that require investigation (13).
Age and Weight at Slaughter: In intensive commercial white pig production, animals reach market weight (~110–120 kg live weight) around 5–6 months of age. For example, in the United States, the average slaughter weight has increased from 116 to 129 kg in 20 years, without modifying finishing facilities (14). In temperate climates (Europe), pigs are usually slaughtered at 22–26 weeks (~5–6 months) weighing 100–120 kg to obtain carcasses of 80–90 kg. (In Iberian pig systems, due to their free-range rearing, the slaughter age is higher, a minimum of 10 months according to regulations) (15).
Replacement Rate and Sow Longevity: The replacement rate is the percentage of breeding sows that are renewed each year. In well-managed farms, it usually stays between 30% and 50% annually, with 40% being a guideline (16). This implies that almost half of the herd is replaced each year, given that a sow's productive longevity is limited to a few efficient farrowings. In fact, it's recommended that a sow produce at least 3–4 litters before culling; removing females before their fourth farrowing compromises reproductive efficiency (17). Consequently, maximizing longevity (farrowings per sow) and adjusting the replacement rate are key strategies for profitability and sustainability, balancing genetic selection and the productive cycle of sows.

Factors Influencing These Parameters

Productive parameters depend on multiple interrelated factors. These include:

Genetics: Determines the productive potential of animals and breeding stock. Hyper-prolific lines have been selected for high prolificacy (more piglets) and rapid growth but often require special care (e.g., more stillbirths, low-birth-weight piglets). More traditional mother breeds (Iberian, colored) exhibit lower prolificacy but sometimes better hardiness (2). Genetics also define growth (ADG) and average conversion. Therefore, the choice of breeds or hybrids (maternal traits vs. finishing pigs) is a critical factor.
Nutrition and Feeding: A balanced feeding plan, adapted to each productive phase, is vital. The quality and quantity of feed directly influence ADG and FCR. For example, dietary problems (insufficient nutrients or unbalanced diets) reduce ADG and worsen FCR. Gestating sow nutrition also affects prolificacy and piglet birth weight, impacting neonatal mortality (17).
Management and Facilities: Includes the housing system (density, ventilation, feeder type), reproductive protocols (estrus synchronization, artificial insemination), farrowing management (comfort of the farrowing bed, assistance), and weaning age (21-28 days recommended) (18). The space per pig in finishing affects feed intake: studies show that from ~105 kg live weight, at least 0.76 m² per pig is required to maintain optimal weight gain (19). Deficient facilities (heat stress, poor hygiene, overcrowding) increase mortality and reduce productivity.
Health: The health status strongly impacts all indicators. Reproductive diseases (PRRSv, parvovirus, etc.) reduce the farrowing rate and increase gestational losses. Pathologies in piglets (diarrhea, pneumonia) increase pre- and post-weaning mortality. Health control (vaccination, biosecurity) is crucial to minimize negative impacts and ensure expected reproductive and growth results.
Environment (climate and comfort): Environmental conditions affect performance. For example, in warm climates (like Spain in summer), it's advisable to reduce animal density in finishing to avoid heat stress; pigs spread out more body surface when lying down to dissipate heat and require more space (20). Extreme temperatures, high humidity, or poor ventilation can decrease appetite and ADG. Adjusting climate control (ventilation, heating) and biosecurity influences mortality and conversion.

In summary, genetics, nutrition, technical management, health, and environment combine to determine productive parameters (21, 22). For instance, Edi Castellanos points out that feed conversion depends on health status, feeder type, technical management, facilities, genetics, environment, nutrition, and personnel training (21). An alteration in any of these aspects can be reflected in a drop in ADG, increased mortality, or deterioration of fertility.

Recommended Reference Values in Technified Systems

Below are guiding values (target ranges) for a technified full-cycle pig farming system with high intensity and advanced genetics:

Prolificacy (total): 14–18 piglets per litter (3).
Farrowing rate: ~85–90% (3–4 percentage points less than 87–95% fertility) (6).
Wean-to-estrus interval (WEI): ~4–7 days.
Daily Gain (ADG) – finishing: 0.8–0.9 kg/day.
Feed Conversion Ratio (FCR): 2.1–2.3 kg feed/kg gained weight (11).
Pre-weaning mortality: <15% (ideally 10–15%) (12).
Post-weaning mortality: <2% (13).
Age at slaughter: ~5–6 months (150–180 days) at 100–120 kg live weight (14).
Replacement (% annual of sows): ~30–50% (≈40% normal) (16).
Sow longevity: ≥3–4 farrowings per sow (before the 4th farrowing) (17).

These values are general: each farm should adapt them to its production model (breed, market, type of feeding). For example, in Iberian pigs, the target weight/mortality differs from intensive white pigs. However, keeping parameters within these ranges ensures a widely accepted level of efficiency and allows for performance comparison with industry standards.

Conclusions and Recommendations

Constant monitoring of productive indicators is essential for improving the efficiency of a pig farm. We recommend:

Regularly record and analyze all key parameters. Investing in data management systems (farm software, spreadsheets) and staff training ensures reliable information (21, 23). For instance, feed conversion should be measured continuously, as it's one of the most influential indices on profitability (23).
Compare results against industry averages. Once data is obtained, comparing it with sectoral benchmarks helps detect deviations. According to Edi Castellanos, "the next step is to compare with the industry average and see when it's off" (24). This allows for identifying incipient problems before they severely affect production.
Adjust management based on results. If a parameter is out of range (e.g., low farrowing rate, slow ADG, high mortality), the cause (feeding, health, stress) should be investigated, and corrective actions adopted. For example, if post-weaning mortality exceeds 2%, biosecurity and the vaccination program should be reviewed (13). If ADG is low, check diet, water, and thermal comfort.
Improve limiting factors. Optimizing genetics (selecting sows with good prolificacy and maternal aptitude), nutrition (adjusting gestation, lactation, and finishing rations), and facilities (ventilation, sufficient space) influence all indicators (20, 21). Maintaining health (vaccinating, isolating new animals) minimizes reproductive and finishing losses.
Promote herd longevity. Implement a good replacement plan that replenishes quality young females without over-sizing the herd. The goal is for breeding sows to achieve several farrowings (≥3–4) before being culled (17), which reduces replacement costs. Selecting gilts with good pedigree and care during the first lactation increases average longevity.

In conclusion, the success of technified pig farming lies in controlling its productive parameters and continuous improvement based on data. Maintaining clear objectives, training staff, and comparing indicators with standards allow for timely detection of deviations and implementation of solutions, thus ensuring profitable, sustainable, and high-quality pig production (23, 24).

Sources: Information adapted from sectoral and technical publications (3tres3.com, Zoetis, MasPorcicultura, scientific studies) on swine management (2, 6, 11, 12, 16, 24), as well as reference data from the pig industry. Each cited value comes from specialized sources in the sector.

(1, 3, 4, 6, 7, 8, 18) Parámetros productivos. ¿Qué debemos conocer antes de realizar una visita a una granja?

https://www.zonaporcino.es/posts/parametros-productivos-que-debemos-conocer-antes-realizar-visita-granja.aspx

(2) Prolificidad - Diccionario porcino - 3tres3, la página del Cerdo

https://www.3tres3.com/diccionario-porcino/P/prolificidad_252/

(5)Tasa de partos o Índice de partos - Diccionario porcino - 3tres3, la página del Cerdo

https://www.3tres3.com/diccionario-porcino/T/tasa-de-partos-o-indice-de-partos_287/

(9) Ganancia Media Diaria - Diccionario porcino - 3tres3, la página del Cerdo

https://www.3tres3.com/diccionario-porcino/G/ganancia-media-diaria_120/

(10, 11, 21, 23, 24) Conversión Alimenticia | MasPorcicultura

https://masporcicultura.com/conversion-alimenticia/

(12, 22) ¿Qué factores influyen en la mortalidad antes del destete?

https://ahvint.com/es/swine/que-factores-influyen-en-la-mortalidad-antes-del-destete/