Feeding Sows RIGHT All the Way Through

Proper nutrition of the breeding herd plays a key role in maximizing herd productivity and profit. Traditional feeding strategies for the reproductive female have used body reserves as a buffer against short-term deficiencies in nutrient intake, resulting in minimal damage to the fetal or suckling piglets. However, modern sows, with a lean genotype and higher reproductive performance, must be managed differently since they start their reproductive life with fewer reserves. It is well established that the way sows are fed in one stage of the reproductive cycle will affect productivity during subsequent stages. As a result, an integrated feeding strategy is needed, starting with the gilt and continuing throughout each successive litter, designed to maintain high productivity and prolong the reproductive life of the sow. The proof that a strategy is working is not only in the longevity and productivity of the sow but also in the performance of her offspring.

Nutrition is the key component that ensures the modern sow achieves her genetic potential for reproduction. In practical terms, the actual level of sow performance in modern herds is well below the animal’s capability. Many farms average 20-22 piglets/sow/year compared with the potential of 30 piglets/sow/year. Table 1 highlights some of the achievable production targets for the modern sow.

Table 1. Production targets for the modern sow
Good Excellent
Sow replacement rate (%) 40 35
Farrowing rate (%) 85 90
Litters/sow/year 2.3 2.4
Empty days/year* <35 <20
Piglets born alive/litter 11.3 12.5
Piglets weaned/litter 10.2 11.3
Piglets reared/sow/year 23.5 27.0
Piglet weight at weaning (kg)** 7.0 7.0
Litter weaning weight (kg) 71 77
Sow feed/piglet weaned (kg) 50 50
Litters per sow lifetime 4 5

* 7-day weaning – mating period
** Piglets weaned at 23 days of age
Source: Close, W.H. 2003. The role of feeding and management in enhancing sow reproductive potential. Proceedings of the 2003 London Swine Conference.

If less than 20% of producers achieve excellent levels of performance, what is holding back the rest? In order to achieve these targets, we need to go back to the basics of sow feeding and develop a strategy that makes sense from beginning to end, from the replacement gilt right through gestation, lactation and re-breeding. There are a number of factors along the way that may help to achieve this level of performance.

When it comes to nutrition, the recipe for success includes everything that replacement gilts and sows need – energy, protein (specifically essential amino acids), essential fatty acids, vitamins and minerals. Without all of these basic building blocks, sows cannot support their requirements for maintenance and growth (body, mammary, and uterine tissue), let alone the requirements for fetal growth. Can you get away with feeding low quality feed to the breeding herd? Sure, but “if you fail to plan, you plan to fail”. The potential consequences can include a decrease in conception rates, smaller litters and/or reduction in birth weight, lower milk production, an increase in weaning-to-service interval, or a shortened reproductive life.

Replacement Gilts

Do NOT feed replacement gilts similar to market hogs. Since gilts selected to enter the breeding herd have superior growth rates and lower backfat levels, they will have higher nutrient requirements than their counterparts headed for the finishing barn. A typical market hog diet will not provide sufficient nutrients to prepare the gilt for a long, productive breeding life. Replacement gilts need higher levels of Ca and P (0.1% above market hog requirements from 50-120 kg body weight – refer to Table 2). These levels will maximize bone mineralization to improve longevity.

Table 2. Nutrient Requirements of Gilts
Item (%) Development Phase (kg)
22+ 45+ 70+ 115+
Protein 18 17 16 15
Lysine 1.0 0.9 0.8 0.7
Ca 0.85 0.8 0.75 0.75
Total P 0.75 0.7 0.65 0.65
Avail P 0.49 0.45 0.4 0.4

Source: Carlson, M.S. 2002. Nutritional Considerations for Breeding Swine. Proceedings of Sow Management Short Course.

Gestating Sows

If there was an overall guiding principle for dry sow feeding, it would be “do NOT overfeed sows during gestation” since it lowers feed intake during lactation. During gestation, feeding levels of 1.8 to 2.5 kg/day will be satisfactory for most dry sows assuming they are housed under reasonable conditions, free of parasites, and are fed individually. Factors that will adjust feeding levels include the size and body condition of the sow, the type of housing and environment provided, the method of feeding, and the health and productivity level of the herd.

Just like people, not all sows are created equal. The heavier the sow, the greater the maintenance requirement and the greater the amount of feed required – for example, energy requirements increase by about 5% (0.1 kg of feed/day) for each 10 kg increase in body weight. Sow body condition is also a key factor. Thin sows have less thermal insulation and are less able to adjust to lower environmental temperatures, and thin sows also require a larger increase in feed at a lower temperature.

Temperature is an important variable to consider in a sow feeding strategy. All animals have a thermoneutral zone, the range of temperatures at which they are most comfortable and their body temperature remains constant. In sows, an environment where the temperature is 1°C below their thermoneutral temperature (20°C) increases their requirement by 3 – 4% more feed.

Restricting feed intake in gestating sows is necessary to limit excessive weight gain and fat deposition, stimulate lactation feed intake and increase overall sow productivity. However, limit feeding does not allow the sow the chance to feel full or satisfied after eating and can lead to frustration and, ultimately, stereotypic behaviours. Feeding fibre during gestation can help address this issue and can also contribute to reduced constipation and over-conditioning, enhanced feed intake in lactation, increased gut capacity, reduced stress, as well as increased litter weight gain and productivity

An important part of any feeding program is the assessment of its effectiveness. There are at least 3 methods to assess how well sows are being fed: body condition scoring, backfat probing and weighing. The most common method is body condition scoring. Ideally producers should chart the body condition score of each sow several times during the reproductive cycle. In the interest of time, a good starting point would be to assess the average condition score for the entire dry sow herd. Armed with this information, adjustments can be made to the feeding levels based on whether the overall average score is greater or less than “3”.

Lactating Sows

It is essential that sows start eating after farrowing and continue to eat well throughout lactation. This is vital since the nutrient requirements of the lactating sow are three times higher than during gestation and, considering current average weaning ages, there is no time to waste. Ultimately the goal is to minimize weight loss (less than 10 kg in 21 days), increase piglet growth rate, decrease piglet mortality, and ensure re-breeding and subsequent reproductive performance. Table 3 lists some practical ways to enhance appetite.

It is important that the temperature in the farrowing room is not too hot for the sow. Heat stress occurs when an animal is unable to remove enough heat from its body. All animals produce heat from digestion. Excess heat production must be lost to the outside environment in order to maintain normal body temperature. Dissipating heat consumes energy, therefore taking energy away from growth or lactation. To complicate matters, pigs that are heat stressed often eat less, making even fewer nutrients available. So, ensure that supplemental heat is provided to the piglets while the sows enjoy thermoneutral temperatures.

Table 3. Practical Ways to Enhance Appetite

  • Feed a well-balanced ration to meet nutrient requirements
  • Gradually increase daily intake then feed ad libitum
  • Offer fresh, palatable feed
  • Feed several times per day, or to appetite
  • Provide 10-12 hours of light
  • Feed pelleted rations instead of meal
  • Ensure fresh water is available at all times
  • Water flow rate should be >2 L/min
  • Avoid exposing sow to high temperatures (<20°C)
  • Maintain good climatic control in farrowing room
  • Do not overfeed during gestation
  • Increase gut capacity by feeding high levels of fibre in gestation
  • Feed separate gestation and lactation diets
  • Proper feeder design – large, open feeders with easy access
  • Improve nutrient availability of diet
  • Provide supplementary feed to piglets
  • Reduce metabolic demand by cross-fostering
  • Ensure comfort of sow

Adapted from: Close, W.H. 2003. The role of feeding and management in enhancing sow reproductive potential. Proceedings of the 2003 London Swine Conference.

Low feed intake during lactation translates into reduced nutrient intake for the sow, higher body weight loss (body fat and protein), reduced piglet growth rate and weaning weight, reduced estrus activity, longer weaning to estrus interval, reduced subsequent litter size and lifetime performance, and a higher culling rate. How do you know whether your sows are getting enough? The common assumption is that the average sow requires 2 kg of feed/day for maintenance and 0.5 kg/pig nursed. AND do not compromise on water. Accessibility to water can limit lactation feed intake so ensure that water flow rates are at least 2 litres/minute.

An integrated feeding strategy that starts with the replacement gilt and supports the sow through each successive litter is the key to maintaining high productivity and prolonging the reproductive life of the sow.

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