Doing so will provide the best probability of piglet survival, not to mention piglet quality.

by Mark Knauer, North Carolina State University

As industry litter sizes have increased, challenges to piglet survival and piglet quality at weaning have frequently ensued.

To maximize farm throughput and promote animal well-being, these challenges should be addressed. While skilled labor and sufficient facilities can largely drive production, the concept of enhancing piglet nutrient access is critical for maximizing piglet survival and piglet quality. The component traits of piglet nutrient access are shown in Figure 1.

Figure 1. The component traits of piglet nutrient access. Image courtesy of the National Hog Farmer.

Piglet Vitality

Piglet vitality encompasses whether a piglet is born alive and, importantly, its vigor at birth.

Low-vigor piglets, often compromised by oxygen deprivation during birth (hypoxia), face significant hurdles in consuming sufficient colostrum for survival. Research indicates a moderate positive correlation between piglet vitality and farrowing duration.

Consequently, strategies aimed at shortening farrowing duration can effectively reduce stillbirth rates and improve newborn piglet vigor.

Given that farrowing duration is a trait with low heritability (heritability is a statistical measure used in genetics to estimate how much of the variation in a particular trait – phenotype - is due to genetic differences among individuals in a population) (<0.10), management interventions appear to be the most promising avenue for improvement.

Several pre-farrowing feeding strategies have shown potential in boosting piglet vitality.

The inclusion of fiber, phytase, and calcium chloride in the sow’s everyday diet has been linked to shorter farrowing times, improved health, and/or fewer stillborn piglets.

Beyond specific ingredients, feeding management practices also play a role.

While gestating sows are commonly fed once daily before farrowing, some studies suggest that feeding multiple times pre-farrowing can reduce farrowing duration and stillbirths.

The timing of these pre-farrowing meals may also be significant, with recent research indicating that feeding closer to midnight, rather than in the morning, could decrease stillborn rates and increase the number of piglets weaned.

Although these findings are encouraging, further investigation into pre-farrowing feeding strategies is warranted to minimize farrowing duration and maximize piglet vitality.

Birth Weight

Past studies have consistently demonstrated that piglets born with low birth weights have a significantly lower chance of surviving lactation compared to their heavier counterparts. Smaller piglets may lack the physical capacity to effectively suckle or face increased competition for nursing.

Interestingly, unlike piglet vitality, nutritional interventions have not proven consistently effective in increasing piglet birth weights.

However, genetic advancements offer a potential solution. Over the past decade, US geneticists have actively worked to improve piglet birth weight through maternal genetics. Furthermore, the choice of terminal sire can influence both piglet birth weight and survival.

Therefore, when selecting terminal sire lines, it’s important to consider their impact on piglet survival and piglet quality at the commercial level.

Colostrum Yield

While adequate colostrum intake is fundamental for piglet survival, not all litters consume a sufficient amount to maximize their chances. Figure 2 illustrates the relationship between average piglet colostrum intake and piglet survival.

Figure 2. Curvilinear relationship between average piglet colostrum intake and piglet survival (litter size at weaning of the biological sow ÷ total number born) for 295 Landrace × Large White composite sows. The average piglet colostrum intake was 467 grams.

As litter sizes increase, sows do not magically produce more colostrum. Therefore, strategies to enhance both sow colostrum production and piglet consumption are essential.

Perhaps the most impactful strategy to increase sow colostrum output is to maximize the number of functional teats.

Recent data from our lab indicates that each additional functional teat can increase litter colostrum consumption by an average of 323 grams.

Nevertheless, more research is needed to explore nutritional interventions that can enhance both the quantity and quality of sow colostrum.

Milk Yield

Similar to colostrum intake, a sufficient level of sow milk production is vital for ensuring piglet survival. Moreover, sow milk yield, in conjunction with piglet birth weight and colostrum consumption, are the primary determinants of piglet weaning weight.

Fortunately, several effective strategies exist to enhance sow milk production.

Both litter weaning weight and litter growth rate are heritable traits, making genetic selection a viable long-term approach to improve sow milk yield.

A potentially faster method involves managing sow nutrient intake. During periods of heat stress, implementing cooling strategies like evaporative cool cell pads and drip cooling can help maintain sow lactation feed intake.

Additionally, the formulation of the lactation diet plays a crucial role. Sows require a threshold level of amino acids to optimize litter weight gain. Therefore, increasing the amino acid concentration of the lactation diet may ensure a greater proportion of sows reach their maximum milk production potential. However, it’s important to note that increasing amino acid levels generally increases feed costs.

Depending on the production system being used, there may be a balance between lactation diet fortification and maximizing milk yield.

Number of Functional Teats

The significance of functional teat number for piglet survival has been recognized for decades.

However, recent research highlights that its importance becomes even more pronounced as the ratio of piglets to teats increases with larger litter sizes. Thus, the number of functional teats has perhaps re-emerged as a critical factor in modern swine production.

Each additional functional teat has been shown to increase the number of piglets weaned per litter by approximately 0.25.

For instance, increasing the average functional teat count of a herd from 15 to 17 could potentially increase piglets weaned per litter by 0.5 piglets.

How do more functional teats enhance piglet survival? As previously mentioned, data suggests they increase overall piglet colostrum intake.

Furthermore, research indicates that additional functional teats reduce the variation in colostrum intake among piglets within a litter.

This reduction in variation is very important because it ensures a higher percentage of piglets receive the minimum threshold of colostrum needed for survival.

What defines a nonfunctional teat? A nonfunctional teat can be a substandard teat (Figure 3) or a teat that has been damaged over time.

Figure 3. Examples of substandard teats in lactation. Substandard teats are teats that may produce no milk or not enough milk to support a growing piglet. Substandard teats can be identified early in a replacement gilt’s life.

Both result in insufficient milk production to support a growing piglet. Importantly, substandard teats can often be identified early in a replacement gilt’s life (Figure 4).

Figure 4. Examples of substandard teats identified shortly after weaning. One may note substandard teats are smaller than the surrounding teats. Substandard teats are teats that may produce no milk or not enough milk to support a growing piglet.

In conclusion, while skilled labor and adequate facilities provide the necessary framework for successful reproductive outcomes, a thorough understanding and proactive improvement of piglet nutrient access are essential for maximizing reproductive throughput and farm productivity.

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Mark Knauer

Dr. Mark Knauer is a Professor in the Animal Science Department at North Carolina State University where his research and extension program focuses on swine genetics and production management.

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