Key Control Points for Enhancing Sow Productivity in Large-Scale Pig Farms

One of the key factors for a pig farm to turn a profit is achieving excellent production performance, and such high production performance largely depends on the reproductive productivity of sows. Sow reproductive productivity refers to each sow’s annual capacity to produce weaned piglets. It is an important indicator that influences the overall production efficiency of large-scale pig farms. To achieve the goals of high productivity, superior quality, and operational efficiency in pig farming, it is essential to enhance the reproductive performance of sows. There are many factors that constrain sow reproductive productivity; the primary critical control points include the following aspects:

1 Maintain a reasonable age structure within the sow population.

The age structure significantly influences the reproductive performance of a sow herd, particularly in terms of its impact on the number of ovulations. The age structure within a sow herd is primarily determined by the length of time each sow is utilized. For most pig breeds, the peak reproductive period for sows occurs between the second and seventh litters; from the eighth litter onward, both the number of piglets born and the survival rate of piglets tend to decline with each successive litter. Based on this, the useful lifespan of sows in large-scale pig farms is typically limited to 3–4 years, with an annual replacement rate of 25%–30%. Sows of each age generally account for roughly 20%–25% of the herd. For sows with higher productivity, their useful lifespan can be appropriately extended. Timely selection and culling of sows are crucial measures for ensuring that a pig farm operates at full capacity and maintains a highly productive sow herd.

2 Shorten the sow’s reproductive cycle, increase the number of litters per year, and enhance the intensity of sow utilization.

The reproductive cycle of a sow includes the mating period, gestation period, and lactation period. From mating until the end of the lactation period (weaning of piglets), it constitutes one complete reproductive cycle. The reproductive cycle is a key factor influencing the sow’s productivity. Among these stages, the gestation period—114 days—is relatively fixed. Therefore, to increase the number of litters sows produce per year, the following factors play a major role:

2.1 Controlling the Initial Mating Age

The appropriate age for first mating can not only achieve higher conception and farrowing rates after initial mating but also extend the productive lifespan of breeding pigs. Under normal rearing conditions, the ideal age and body weight for first mating in sows are as follows: for introduced breeds, 8 to 10 months old with a body weight of 110 to 120 kilograms; for local breeds, 6 to 8 months old with a body weight of 60 to 70 kilograms.

2.2 Fertility Rate During the Estrus Period

The proportion of sows that can become pregnant during their first estrus cycle—when they are ready to conceive—is typically between 85% and 90%. A lower conception rate during estrus can prolong the sow’s non-productive period—the so-called “empty days”—which not only reduces the number of litters produced per sow annually but also leads to wastage of feed and labor, thereby increasing pig-raising costs. This is currently one of the primary factors affecting the annual litter production of sows. To address this issue, it’s crucial to keep the weight loss of sows before farrowing and at weaning within a range of 10 to 15 kilograms. Once weaned, sows should be encouraged to come into heat as soon as possible. Under normal circumstances, more than 95% of sows will show signs of estrus within 3 to 5 days after weaning.

2.3 Fetal Birth Rate

The proportion of sows that give birth relative to the total number of pregnant sows indicates the farrowing rate. The higher the farrowing rate, the greater the number of litters a sow can produce annually. During this period, the primary source of loss is abortion. Placing pregnant sows in the same barn, avoiding arbitrary group transfers or mixing of groups, and strengthening management during the gestation period can effectively reduce the incidence of abortion.

2.4 Lactation

Implement early weaning and shorten the lactation period to reduce the sow’s reproductive cycle. However, do not blindly pursue early weaning solely to increase the number of litters produced per sow per year. Instead, prioritize ensuring that piglets can grow and develop normally after weaning. Determine the optimal weaning age based on the actual production conditions of your farm; generally, weaning at 21 to 28 days of age is advisable.

Therefore, to shorten the interval between farrowings and increase the number of litters produced annually by sows, comprehensive management measures should be adopted. First, it is essential to ensure that the sow’s reproductive tract quickly returns to normal. Under conditions of improved appetite, the diet should be appropriately formulated to enable sows to attain an optimal body condition at weaning. At the same time, on the first day after weaning, the diet should be carefully controlled, and sows should be housed in small groups. Some farms also place sows near boars to stimulate estrus. If necessary, gonadotropin-releasing hormones can be used to induce estrus. Sows with fewer piglets or poor lactation performance can have their piglets fostered to sows that farrow around the same time. Early weaning techniques can be employed to help sows recover from estrus and become ready for mating sooner, thereby increasing the annual number of litters. For sows that show signs of estrus again within 21 days after mating—accounting for more than 5% of all mated sows—careful examination is needed to determine whether the breeding boar is experiencing over-mating or has poor semen quality.

3 Improve fertilization rates, strengthen pregnancy management, and increase the number of live, healthy piglets per litter.

3.1 Mating Stage

The quality of boar semen, the body condition score of sows, and the timing of optimal mating are the primary factors determining litter size. Strengthening the management and care of boars, establishing a reasonable daily routine and semen-collection protocol for boars, and ensuring high-quality boar semen are crucial. Compared to natural mating, the application of artificial insemination technology can largely guarantee semen quality, reduce the cost of raising boars on-site, and fully harness the superior genetic traits of boars. After selecting high-quality boars for semen collection, sperm motility should be examined under a microscope; only when sperm motility reaches or exceeds 0.7 can the semen be used for artificial insemination of estrous sows. Proper insemination techniques can help minimize the transmission of reproductive tract diseases.

3.2 Estrus Detection and Timely Mating

The estrous cycle of sows lasts between 20 and 22 days, with an average of 21 days. The duration from the onset to the termination of estrous signs in sows is 60 to 72 hours, while ovulation occurs approximately 36 to 40 hours after the appearance of estrous signs. Therefore, accurately identifying the estrous condition of sows is essential for achieving timely mating. Estrus detection in sows primarily relies on external genitalia observation, combined with the back-pressure reflex and test mating with a boar, and thorough records should be kept. Taking into account factors such as the sow’s breed and parity, the optimal mating time can be determined. Generally, after a sow exhibits the "standing reflex," the first mating can be carried out 8 to 12 hours later. Mating should be repeated 2 to 3 times, with an interval of 12 hours between each mating.

3.3 Measures to Enhance Estrus and Ovulation in Sows

First, improve the conditions of feeding and management by grouping weaned sows that are not yet pregnant into small groups and providing them with short-term enhanced feeding. In particular, gilts should receive short-term enhanced feeding for 14 days prior to mating, increasing their daily feed intake by 0.5 to 0.7 kilograms to promote ovulation and conception. Second, you can employ boar-induced estrus: group sows together in pens, and place sows that are not in heat into pens with sows that are already in heat. The act of mounting and stimulation from the dominant sows will help induce estrus in the non-cycling sows. Additionally, exogenous hormones can be used to induce estrus.

3.4 Strengthen management of sows after mating to reduce embryonic mortality.

To reduce embryonic mortality, measures should be taken during the three critical periods of high mortality—namely, the early implantation stage of the zygote from days 9 to 13 after fertilization, week 3 of gestation, and days 60 to 70 of gestation. In addition to formulating a complete feed according to feeding standards, avoid feeding moldy, spoiled, deteriorated, frozen, or feed containing toxins and strong irritants. Feed changes should not be made too frequently. Generally speaking, increasing the level of feeding before ovulation can boost the number of ovulations, while restricting feed intake in sows after ovulation can help lower the rate of embryonic mortality. In the late stages of gestation, appropriately increase the frequency of feeding. During management, take precautions against crushing and falls, and strictly prohibit whipping. In summer, install heat-prevention and cooling equipment, enhance greenery, use cool-water misting for cooling, ensure an adequate supply of clean drinking water, and minimize the impact of heat stress.

4 Strengthen management of lactating sows to enhance their milk production.

4.1 Feed Intake During Pregnancy

Excessive feed intake can affect the appetite of lactating sows, leading to insufficient milk production. For pregnant sows, adopt a nutritional strategy that starts with lower levels and gradually increases toward the end of pregnancy—specifically, by controlling the amount of feed given during gestation to keep weight gain within the range of 30 to 40 kilograms.

4.2 Ensuring the Nutritional Needs of Lactating Sows

The quality and quantity of feed consumed by sows directly affect the amount of milk they produce. During the lactation period, it is crucial to enhance the nutritional support provided to sows by offering a diet high in energy and protein, with no restrictions on the amount fed. At the same time, it is essential to meet their nutritional needs for minerals (calcium, phosphorus, salt, and trace elements) as well as various vitamins, and to ensure that they have access to sufficient drinking water.

4.3 Environment

The primary goal is to create a quiet and comfortable environment for lactating sows. In winter, pay attention to keeping them warm; in summer, focus on cooling them down. Also, promptly treat any sick pigs.

5 Strengthen piglet care to improve piglet survival rates.

5.1 Care of Nursing Piglets

First, a dedicated person should be assigned to assist with farrowing to minimize piglet mortality during the birthing process. The farrowing crate should be equipped with an incubator; within the first three days after birth, the temperature inside the incubator must be maintained above 30°C. Immediately after birth, piglets should be manually assisted to ensure they consume sufficient colostrum, which helps stimulate the activity of their digestive organs, promotes the elimination of meconium, enhances nutrient absorption, and boosts their immune system. Within 2 to 3 days after birth, the piglets’ nipples should be properly identified and assigned to specific piglets. Intensive care is essential to prevent the sow from accidentally stepping on or crushing the piglets.

5.2 Supplement iron, replenish fluids, and provide feed.

The iron content in sow's milk falls far short of meeting the nutritional needs for piglets' growth and development, so artificial iron supplementation is essential. Typically, within 3 to 4 days after birth, piglets should receive an intramuscular injection of an iron preparation at a dose of 150 to 200 milligrams per piglet. Sow's milk has a high fat content, and piglets have a vigorous metabolism with high water requirements. Therefore, it is generally recommended to start training piglets to drink from a water dispenser around 3 days after birth, to prevent them from drinking contaminated water that could cause diarrhea. Starting from 7 days after birth, piglets should be gradually introduced to solid feed to promote the development of their digestive organs and the maturation of their digestive functions. Feeders must be kept clean, and feed should be replenished 5 to 6 times daily to ensure freshness.

5.3 Foster Care

When several sows farrow at the same time, piglets with excessive or insufficient numbers of offspring, or those born without milk or with low milk production, should be promptly fostered to improve their survival rate. However, it’s crucial that the fostered piglets receive colostrum as soon as possible. The sows chosen for fostering must have farrowing dates that are close—no more than 3 to 4 days apart—and the fostered sows should be gentle in temperament and have good lactation performance.

5.4 Preventing Diarrhea

Piglets have immature digestive, thermoregulatory, and immune functions, making them prone to diarrhea, which can severely compromise their survival rate. Therefore, it’s crucial to strengthen care during the piglet stage to prevent diarrheal diseases. First and foremost, it’s important to properly raise the sows to ensure high-quality milk. Additionally, provide piglets with adequate iron and hydration, maintain strict hygiene in the pigsty, and create a clean, comfortable, and warm environment for their growth.

6 Pig Health

Currently, large-scale pig farms are all facing varying degrees of disease challenges, particularly diseases that cause reproductive disorders in sows, such as swine fever, blue ear disease, pseudorabies, parvovirus, Japanese encephalitis, endometritis, and PCV-2. These diseases lead to reduced sow fertility, increased rates of abortion, stillbirths, and weak piglets, directly impacting sow reproductive performance. To address this issue, we should start by purifying the farm from pathogens and improving the environment while strengthening feeding and management practices. For breeding herds, it is essential to conduct regular disease screenings, cull positive animals, and administer various vaccines rigorously according to scientifically sound immunization schedules. Moreover, it is advisable to develop detailed health care plans tailored to the specific conditions of the breeding herd on a regular basis—ideally, once a month for a period of 3 to 5 days each time. Thorough disinfection of pig houses is crucial, adhering to the principle of "prevention first, combined prevention and treatment, with prevention being more important than cure." We should also improve the environment, enhance management practices, provide nutritionally balanced feed, and create a comfortable living environment for pigs to boost their innate immune resistance.

In short, every aspect of sow management is closely linked to the sow’s annual productivity. Currently, as sow production performance continues to improve, high-producing sows have increasingly higher nutritional requirements—particularly for amino acids, vitamins, and trace minerals. In response to this situation, Xilai Gao Company has launched the “Wang Wang” Sow Program (incorporating Nai Jia Wang + Wei Si Wang into the feed), which provides a balanced supply of amino acids, adequate vitamins, and essential minerals to meet the nutritional needs of sows and thereby enhance their reproductive performance.