Precision is of vital importance for improving the health of sows, the efficiency of reproduction, and the growth of piglets.

The production and nurturing process of sows is a stage with extremely high energy demands. During their gestation and lactation periods, sows undergo significant physiological changes. The energy requirements during this period are influenced by multiple factors such as the number of offspring, body condition score, and environmental conditions. Accurately understanding the energy requirements of sows is crucial for ensuring their health, improving reproductive efficiency, and promoting the growth and development of piglets. This directly affects the production efficiency of large-scale pig farms.

Energy requirements during pregnancy

The energy requirements during pregnancy include the maintenance energy needed to sustain the basic metabolic functions of the sow, as well as the additional energy required for the growth of the fetus, the development of the uterus and placenta, and the increase in the mother's body weight.

The maintenance metabolic energy (MEm) can be calculated using the metabolic weight formula as per the study by Samuel et al. (2024): 

● MEm = 0.506 × Body Weight (kg)^0.75 × Megajoules (Metabolic Energy per Day) 
Similarly, the maintenance of net energy (NEm) can be calculated using the formula proposed by Li et al. (2024): 

● NEm = 0.410 × Body Weight (kg)^0.75 × Megajoules (Net Energy/Day) 

For a sow weighing 205 kilograms, the maintenance energy requirement is approximately 6,550 kilocalories of metabolizable energy (ME) or 5,309 kilocalories of net energy (NE) per day. As the gestation progresses, due to the growth of the fetus, an additional 120-190 kilocalories of energy is required per day for each additional fetus (Quiniou et al., 2001). For a sow carrying 13.5 piglets, this means an additional 1,620-2,565 kilocalories of energy is needed per day during the late gestation period. Therefore, the total energy requirement during the late gestation period ranges from 8,170 to 9,115 kilocalories per day. 

As a comparison, the National Research Council of the United States (NRC 2012) suggested: For multiparous sows with an expected weight gain of 40 kilograms and giving birth to 13.5 piglets, the effective metabolizable energy intake before 90 days of gestation should be 6,450 kilocalories per day, and 7,650 kilocalories per day after 90 days of gestation. Based on this calculation, the cumulative energy requirement during the 115-day gestation period is estimated to be 795-820 megacalories.

Energy requirements during lactation

The energy requirement of sows during lactation is the highest, mainly due to the energy consumption for milk production, which is crucial for the growth and survival of piglets. The daily milk yield of sows is typically 8-12 kilograms, and the energy cost required for each kilogram of milk production is 8-10 megajoules (MJ) (Noblet & Etienne, 1989). Taking a sow that produces 12 kilograms of milk per day as an example:

● The energy required for milk production = 12 kilograms/day × 8 megajoules/kilogram = 96 megajoules/day (approximately 22.9 megacalories/day).

Apart from milk production, the maintenance energy requirement of sows is still approximately 6,550 kilocalories/day (6.55 megacalories/day). Therefore, the total energy requirement of high-yielding sows during lactation can reach 29.5 megacalories/day. Based on a typical 21-day lactation period, the total energy requirement is approximately 620 megacalories.

The total energy input for each litter of piglets

Combining the energy requirements during pregnancy and lactation, the total energy input required to produce a litter of piglets and complete the lactation process is approximately the sum of the energy requirements during pregnancy (795-820 Mcal) and lactation (620 Mcal). Therefore, the total energy requirement is 1415-1440 megacalories (Mcal), with the specific value being influenced by factors such as the number of piglets born, milk production, and the weight of the sow.

Assuming a multiparous sow that has given birth to three litters has a typical feeding pattern during pregnancy (daily feed intake of 4 pounds of feed per day * 1500 kilocalories per pound = 6000 kilocalories per day) and lactation (daily feed intake of 18 pounds of feed per day * 1500 kilocalories per pound = 27 megacalories per day), current industry conventional feeding practices indicate that the energy intake from feed by the sow is insufficient to fully meet the energy investment required for producing a litter of piglets.

Implications for feeding strategies

Meeting these energy requirements is crucial for maintaining the health of sows and optimizing their reproductive performance. Insufficient feeding during pregnancy can lead to lower birth weights of piglets and a decline in the body condition of sows, while insufficient energy intake during lactation can result in excessive weight loss in sows, reduced milk production, and prolonged estrus intervals (Dourmad et al., 1998). When formulating feeding plans, the following elements should be given priority consideration:

1.Number of offspring and production stage: Energy requirements increase with the increase in the number of offspring and reach their peak during the lactation period. 

2. Diet composition: A high-energy diet consisting of fats and oils can meet energy requirements without increasing feed intake (Quiniou et al., 2001). 

3. Environmental conditions: The temperature inside the barn and the ventilation system can affect energy requirements, as sows need to consume energy through thermoregulation (NRC, 2012). 

The precise feeding strategy adjusts the energy intake based on the production stage of the sows and their individual needs, which is of vital importance for optimizing production outcomes. 

Giving birth is a significant energy expenditure for sows, with the energy consumed during the lactation period accounting for the majority of it due to the milk production requirements. Accurately estimating energy needs (including maintenance requirements) is the foundation for formulating effective feeding strategies, which can support the health of sows, promote the growth of piglets, and enhance overall production efficiency. Through advancements in nutrition and management practices (such as precise feeding), producers can efficiently meet these needs while ensuring animal welfare. 

National Hog Farmer—《Energy requirements for sows to produce a litter》

By Ryan Samuel Published on January 16, 2025.1.16

The copyright belongs to the original author.