Correct and balanced nutrition should be provided to pregnant sows to obtain the best reproductive and productive performance.

Pigs are a species of animals that generate high productive performance due to their efficient feed conversion. For this reason, breeding sows are considered hyperprolific since they can have many piglets at each farrowing. To ensure that sows can have a healthy and optimal gestation stage, all the required nutritional components must be provided.

These dietary components ensure that the piglets in gestation (embryos during the first weeks and fetuses for the rest of the time) grow with the best parameters. In addition, they allow all functions and systems of the pregnant sow to be in the best condition during the reproductive period.

Sow body condition: a guide to welfare

Breeding sows require the best animal welfare parameters. Among these, body condition is a guide to determine the amount of body fat the animals have and indicate whether the feed is sufficient for their metabolic expenditure.

To determine the body condition index, the operator or veterinarian makes a visual examination from the rear of the sow when she is standing. The rating is listed from 1 to 5, with 1 being the lowest value when the sow has a low-fat percentage and 5 being the highest value when the sow has excess body fat.

In addition, the evaluator can rely on manual palpation of structures to determine the body condition (CC) classification more accurately as follows:

• CC1: the sow is considered emaciated or excessively thin, on palpation the vertebrae of the spine are prominent and noticeable to the naked eye. This seriously compromises the viability of the gestation.
• CC2: the sow is considered skinny; the prominences of the pelvis and spine are easily palpable and easily observed. Gestation may be compromised by malnutrition.
• CC3: the sow has an ideal and optimal body composition, where the pelvic prominences and vertebrae of the spine are not observed and by palpation are not completely identified. The pregnant sow has an optimal condition for reproductive viability.
• CC4: The sow is moderately obese, where the pelvic bones and vertebrae of the spine cannot be identified by palpation and are not observed. The sow’s body has a cylindrical shape.
• CC5: The sow is considered excessively obese; the bones of the pelvis and spine cannot be identified by palpation or observation.

The stages of gestation in the sow

The time when sows are about 4 months of age, contact with boars can be initiated so that the flock can more easily come into estrus later. Contact of gilts with boars has been found to improve estrus rate and early onset of the first estrus. Further on, the presence of the boar will facilitate the detection of estrus in the sows to perform artificial insemination on time.

On the other hand, this management allows sows in the fattening phase to reach their physiological and reproductive maturity, thus becoming breeders and ensuring the farm’s genetics without the need for replacement.

Before breeding stage starts, the sow must be 6 months old and reach a certain weight, within which the percentage of fat must be a maximum of 1%. For this purpose, a change is made in the sow’s diet and exercise is promoted to reduce the amount of body fat. In this way, the body condition of the sow is characterized by having a large amount of muscle and complete development of the bones to support the locomotor system, keeping little fat.

The gestation of the sow means high demand for nutrients to maintain the embryos and later growing fetuses, as well as to maintain the sow’s body functions. Therefore, proper diet helps the sow to recover and maintain her body reserves, reduces embryonic mortality and fetal loss, and prepares the sow for the resting stage and the next gestation.

Feeding at each stage of a sow’s pregnancy

The sow’s complete gestation takes an average of 115 days, where the goal is to obtain the highest possible number of piglets born alive and with the highest weight in the litter.

• First part (0 to 35 days): the correct feeding of the sow in this stage, as well as a complete sanitary plan, must guarantee that the pregnant sow does not have embryo reabsorption. This loss of embryos generates economic losses and affects the health of the sows.
• Second part (35 to 75 days): the feeding of the sow in this period must guarantee that the sow recovers her condition and prepare her for the next lactation. In addition, pregnant sows at this stage can grow according to their age and genetics. The excessive fat accumulation that affects the viability of gestation or lactation due to fat deposits in the mammary glands should be avoided.
• Third part (75 to 110 days): during this period, the sow should be fed a diet that provides the necessary nutrients for optimal fetal growth, as well as for the final adaptation of the mammary gland for lactation. It also prepares the sow for farrowing and prevents her from entering a negative energy balance.

Importance of nutrition in the pregnant sow

Feeding should allow the sow to reach the ideal body condition to carry out gestation. In this way, the piglets grow properly, and the sow can reach farrowing with less probability of problems such as dystocia, stillbirths, among others. In addition, this feeding will also be decisive in the production of colostrum that provides defenses for the recently farrowed piglets and milk during the rest of the growth stage.

For the sow to produce milk in sufficient quantity and of high quality, all dietary requirements should be provided (Table 1). If the farm can achieve proper lactation, the piglets will grow more efficiently, healthier, and stronger against disease.

Milk production in the sow for piglet feeding is a key factor that depends on several factors. The sow’s mammary gland must be healthy to lactate properly. Farrowing factors also play a role, with litter size and the number of births being two key aspects. Other factors considered are breed, genetics, environmental stress, and management.

On the other hand, during gestation the size of the pregnant uterus causes a reduction in the stomach’s capacity to digest feed, so sows consume less. To avoid this, green feed is incorporated into the diet so that the sow perceives hunger and increases feed consumption, avoiding the reduction of the stomach. Otherwise, if after farrowing the sow has a reduced stomach and consumes less feed, the amount of milk produced could be less.

When the sow consumes sufficient feed, weight loss is avoided and therefore she has optimal lactation. In addition, this stimulates the next ovulation cycle to be normal by releasing 14-15 ovules, while in weak or malnourished sows this ovulation can be reduced to 4-5 ovules per cycle.

Table 1. Nutritional requirements of the pregnant sow.

Impact of poor feeding in sows

Poor quality or poor quantity of diet fed to sows can harm pig production. These effects are associated with malnutrition or overweight processes; in both cases, there are deleterious effects on sow health and productive performance. Some of these effects are:

• Increased embryonic mortality
• Litters with a lower number of piglets at each farrowing
• Lower feed intake during lactation and low milk production.
• Higher replacement rate close to 50%.
• Longer calving interval
• Loss of backfat and weight loss in cases of malnutrition.

Strategies for feeding during gestation in sows

Strategies for good feeding of sows during gestation and farrowing should be multifactorial and comprehensive. Thanks to this, the productive life of the animals can be developed in conditions of welfare, optimal production, and favorable economic returns.

• Complete sanitary plans that include internal and external deworming at the appropriate times and with products approved for use in sows.
• Keep the resting and feeding areas of pregnant sows completely clean and perform periodic disinfection, especially in the farrowing area.
• Control feed consumption during gestation and farrowing to avoid malnutrition or overweight in pregnant sows that affect this stage of milk production.
• Provide the diet in periodic rations throughout the day and avoid offering it at midday or at times of excessive heat as this increases the probability of caloric stress.
• Always provide water at adequate temperature (cold). It is recommended to perform a physicochemical and bacteriological analysis of the water to reduce the probability of diseases.
• The product Alquernat Nebsui elaborated by Biovet S.A. contains pronutrients that improve the nutritional processes in sows. Pronutrients promote the regeneration of intestinal cells (enterocytes), improve nutrient absorption, optimize digestive processes, and replace growth-promoting antibiotics.

This intestinal conditioner has shown remarkable results in in vitro, in vivo, and field trials with pigs, where the animals had better feed conversion rate and growth rate. In addition, its role in the prevention of infectious diseases of the digestive tract such as Clostridiosis has been demonstrated.

Conclusions

Feed is the most important component of any animal production system in the world. In swine, it plays a fundamental role in the correct development of the animals and their productive stage.

Pregnant sows are the most important age group in any swine farm since they provide the piglets of the system. Therefore, it is necessary to provide adequate feed to these females.

On the other hand, it is recognized that sow gestation can be divided into three key stages where feeding changes to meet the requirements of each stage. In this way, pregnant sows have an optimal diet that allows them to reach farrowing and start lactation without problems. These last two processes are of great importance for the growth and development of piglets in the best conditions.

Finally, it should be noted that inadequate feeding could generate health problems in the sow that seriously affect the production system. Therefore, strategies are implemented to optimize the feeding process of sows to ensure their production under the highest standards of animal welfare.