Previously, in this series of articles, we discussed some critical indicators in sow management, focusing on sow parity and litter size (Part 1) and how feeding younger and older sows differently can improve progeny performance (Part 2). This third piece will focus on the main factors that can impact sow and piglet performance during the lactation period. As we know, there are many factors to consider when it comes to maximizing performance during lactation, and sow farm managers must prioritize those that have the largest impact. Let's dive in.  

As we all know, there is a significant number of risk factors that can influence sow reproductive performance. Two of the major ones are sow nutrition and feed intake, as feeding lactating sows properly is critical to maintaining optimal reproductive performance. Because of this, swine nutritionists must use the best strategies and ingredients to minimize the loss of the sow’s body reserves, while maximizing the sow’s milk production and, consequently, optimizing litter performance. 

To guarantee that, increasing feed intake in sows during lactation is vital. Craig et al. (2017) reported that the ADFI of lactating sows is 5.7 kg/day on average, and consumption can go higher than 7.7 kg/day over a 28-day lactation period. It’s also worth mentioning that sows will have a greater appetite during lactation if they achieve optimum feed intake during gestation. Additionally, the diet composition is also essential: Modern sows require greater levels of energy and lysine and need a micro-nutritional approach during lactation that will support piglet performance by ensuring that both sows and piglets are receiving optimal levels of minerals and vitamins. 

Some strategies can be applied to achieve higher levels of sow feed intake, such as: 

• Always provide fresh feed; 
• Don’t underestimate the importance of the quality and quantity of water; 
• Provide ad libitum feeding for lactating sows; 
• Feed younger and older sows differently, as they have different appetites and nutritional requirements. 

Experts suggest that sows should be fed three times a day or even more, and using automated feed systems can help to increase feed intake even further. For example, when evaluating a group of 84 sows, Sulabo et al. (2010) reported that reduced feed intake during lactation negatively affected sow and litter performance.

Consequently, increased feed intake in sows during lactation, and appropriate dietary energy and essential amino acid concentrations, improve the welfare and productivity outcomes for both the sows and the piglets. Craig et al. (2017) conducted a study with 82 sows fed with normal (15.2 MJ/kg DE; 1.28% total lysine) or high (15.8 MJ/kg DE; 1.3% total lysine) nutrient levels, combined with either a low (feed allowance was increased by 0.3 kg/d after farrowing until intake reached 7.5 kg/d) or high (feed allowance was increased by 0.5 kg/d after farrowing until intake reached 10 kg/d) feeding level. Results from this study suggested that sows fed with low feeding levels lost more body weight when compared to sows fed high feeding levels and sows fed high nutrient levels lost more body weight during lactation when compared to sows fed normal nutrient levels. Additionally, litters of sows that were given the high feeding level were heavier at 28 d (114 kg) and grew faster (326 g/day). Moreover, piglets from sows fed the high nutrient level diet had greater ADG (+190 g/day) between birth and weaning when compared to pigs fed normal nutrient levels, though final litter body weight did not differ. 

Taking this into consideration, lactating sow nutrition affects not only the sows but also litter outcomes. Experts highlight that feed intake during lactation is linked to sow milk production and body mobilization (Strathe et al., 2017); the more the sow eats, the more milk that is produced. However, lactating sows turn catabolic to maintain their milk production because they cannot increase the feed intake at the same rate that milk production is increasing. In regard to this, Strathe et al. (2017) reported that low feed intake causes an increase in body mobilization and, consequently, has adverse effects on subsequent reproductive indicators. 

Another critical factor to consider when discussing pre-weaning performance and the survival of piglets during lactation is colostrum/milk intake. We all know the importance of providing colostrum to newborn piglets, as it plays an essential role in their survival as it is the primary source of energy and immunoglobulins. However, we often forget that the quality and quantity of colostrum and milk start with quality sow nutrition. Thus, sows must be able to support the piglets’ immune development and activation by transferring critical nutrients, such as vitamins and minerals. 

Because of this, colostrum and milk intake are associated with greater piglet birth weight and daily weight gain. In a recent study, Juthamanee and Tummaruk (2021) evaluated 861 live-born piglets from 59 sows (parities 1-6). Regarding piglet performance, data from this experiment showed that colostrum intake has a positive correlation with piglet birth weight (r = 0.250, P < 0.001), body weight gain (r = 0.927, P < 0.001) and rectal temperature (r = 0.200, P < 0.001). The authors also suggested that body weight at birth, cumulative birth interval, and litter size are risk factors that can affect the piglets’ colostrum consumption.

Colostrum intake also plays a significant role in piglet survivability, especially for low-birth-weight piglets. Piglets that don’t consume an appropriate amount of colostrum in the first hours after birth are susceptible to starvation, crushing, and diarrhea, which are some of the major causes of pre-weaning death (Kilbride et al., 2012). With this in mind, Ferrari et al. (2014) have shown that dead piglets - from 24 hours after birth to 42 days of age – had consumed less colostrum when compared to surviving piglets (197.5 ± 16.3 g vs. 291.6 ± 6.5 g). This is also reflected in birth weight (1.24 ± 0.02 kg vs. 1.31 ± 0.01 kg) and IgG concentration 24 h after birth (18.1 ± 1.1 vs. 22.0 ± 0.8 mg/ml). In turn, the study proposed by Juthamanee and Tummaruk (2021) showed that the piglet mortality rate declined from 88.8% to 6.3% when the colostrum intake increased from less than 100 g to over 300 g.

Thus, multiple factors can influence lactating sows, their litter performance, and sow herd profitability. In a cascading effect, inadequate feeding programs for the sows limit their reproductive success and the productivity of the entire sow farm system. Taking that into consideration, this article has discussed two critical factors that the farm manager must record and evaluate; sow and piglet feed intake. As we can see, maximizing the feed intake of sows and the colostrum/milk intake of piglets during lactation will improve performance, survivability, and the associated welfare and economic outcomes.