Authors:
Jordi Camp (PIC® Europe Nutrition Team) Pablo Magallón, Maria Ros, Patricia Blanco, Serhii Shevchenko, Adrian Lopez, Isaac Huerta (PIC® Southern Europe Technical services).
There are different nutritional strategies to address post-weaning challenges, such as: reduction of crude protein (CP) in the diet, use of high digestible protein sources, amino acid ratios, functional amino acids, formulating to lower stomach pH, vitamins and minerals, fibre sources, particle size, lactose inclusion levels, feed additives, etc.
Reducing crude protein levels
The early post-weaning period should focus on preserving the intestinal health of piglets to avoid a high incidence of DPD. Therefore, it is important to consider the pH of the piglet’s stomach in order to have a good digestion of feed and to preserve a healthy and functional gut. At weaning, piglets have a low production of hydrochloric acid (HCl) in the stomach and the solid feed has a high buffering capacity due to milk by-products, high protein raw materials and minerals (Bonetti et al., 2021; Lawlor et al., 2005). The latter decreases protein digestibility and undigested proteins can reach the distal parts of the intestine increasing the incidence of DPD due to increased fermentation and proliferation of bacteria such as E. coli in the large intestine (Pieper et al., 2016; Wellock et al., 2008). Thus, reducing the percentage of CP in the diet is one of the main nutritional strategies to avoid a higher incidence of DPD (Heo et al., 2015).
Use of highly digestible protein sources
The decrease in CP percentage can be accompanied by an increase in the use of highly digestible protein sources in these early post-weaning diets. The use of highly digestible protein raw materials allows for higher protein digestibility and prevents undigestible or fermentable proteins from reaching distal parts of the intestine, increasing DPD (Tokach et al., 2021). Examples of highly digestible protein sources used in post-weaning diets include whey protein, fish meal and porcine plasma. In addition, soybean meal can be used when it has been treated to reduce its anti-nutritional factors and can partially replace animal protein sources without compromising pig health and performance.
Consider the amino acid profile
Furthermore, it has been observed that diets supplemented with crude protein and diets supplemented with synthetic amino acids can help improve faecal consistency and mitigate DPD (Heo et al., 2010; Yue & Qiao, 2008). However, it is important not to overfeed lysine (Lis) and provide an unbalanced amino acid profile. In the PIC nutrition and feeding manuals, we recommend a maximum ratio of 6.4 standardised ileal digestible Lis (SID):CP in piglets from 4 to 9 weeks of age based on the results of Millet et al. (2018). In addition, the amino acid to digestible lysine ratios recommended in the PIC nutrition and feeding manual are: 58% Met-Cis:Lis, 65% Thr:Lis, 20% Trp: Lis, 67% Val: Lis, 55% Ile:Lis, 100% Leu:Lis, 32% His:Lis, and 94% Phe-Tyr:Lis. It is also important to consider functional amino acids that can help in this challenging period, such as threonine, tryptophan and glutamine. These amino acids have a role in improving and maintaining gut development and health. (Huting et al., 2021).
Formulate to lower stomach pH
Lowering stomach pH will facilitate protein digestion and reduce the incidence of DPD. The acid binding capacity (ABC) of dietary ingredients could be considered to formulate towards a low stomach pH. ABC defines the buffering capacity of feed ingredients based on their resistance to pH changes. Ingredients with a high ABC-4 value (ABC at pH 4) will have a greater impact effect on neutralising stomach pH than those with a low ABC-4 value (Lawlor et al., 2005; Molist, 2022). The target ABC-4 value should be considered to be around 250 meq/kg in the first two post-weaning diets (Molist, 2022). The latter will depend on the crude protein, ash and mineral content (Molist, 2022). Thus, a low level of crude protein in the diet will help to reduce the ABC-4 value. The type of protein source provided will also influence the ABC-4 value (Lawlor et al., 2005). Calcium should also be considered and reduced in early post-weaning diets to reduce buffering capacity (Tokach et al., 2021). Calcium carbonate can be replaced by calcium formate (Lawlor et al., 2005). In addition, the use of organic acids in diets such as benzoic, formic or butyric acids, among others, should be considered. Organic acids play a role as acidifiers by lowering the pH of the stomach, improving protein digestion and intestinal health, and reducing DPD (Bonetti et al., 2021).
Vitamins and minerals
It is important to ensure that diets are correctly fortified with levels of vitamins and minerals to meet the demands of piglets. Vitamin E and selenium are antioxidants that are always important in terms of health (NRC, 2012). Also, the positive effect of therapeutic levels of zinc oxide in piglet diets to control DPD has long been recognised (Bonetti et al., 2021). However, in some countries it is no longer allowed to use therapeutic levels of zinc oxide in piglet diets (Bonetti et al., 2021; EFSA, 2014; European Commission, 2017). However, in such diets it is important that zinc levels are sufficient to meet the pig’s requirements without exceeding the legal level set by country or region. Copper when provided between 100-250 ppm can stimulate a growth response in pigs (Cromwell, 1997), which has been attributed to its antimicrobial action (Fuller et al., 1960). Also, previous research has observed that feeding these levels of copper improves faecal consistency, reducing the percentage of DPD in weaned piglets (Bikker et al., 2015). However, some countries or regions may have restrictions on the inclusion of copper levels in the diet (European Commission, 2018). There is also a range of organic minerals that claim higher bioavailability and may be worth considering. Organic sources of copper with higher bioavailability, such as Cu-amino acid chelate, also appear to have potential to influence growth in pigs (Carpenter et al., 2019). Organic sources of zinc have not consistently shown the same results as zinc oxide when the organic source is used at lower levels (Hollis et al., 2005).
The functionality of different fibre sources
Fibre has also been considered in post-weaning diets in terms of its functionality. There are two types of fibres depending on their fermentability: inert and fermentable. In early post-weaning diets, the use of an inert fibre can contribute to decrease fermentation, intestinal dysbiosis and DPD (Bonetti et al., 2021). Previous research reported that inert fibre improves intestinal morphology and motility (Huting et al., 2021), average daily intake and average daily gain (Fernandes et al., 2020; Gerritsen et al., 2012), and decreases E. coli adhesion in the intestine (Molist et al., 2010, 2011, 2012). Therefore, fibres such as lignocellulose, oat hulls, wheat bran, sunflower hulls and wheat straw should be considered due to their high proportion of non-starch polysaccharides. The level of energy in the diet will be related to the level of fibre in the diet. Based on evidence that inclusion of different fibre sources can be helpful in terms of controlling DPD, it may be sensible to include some fibre sources in piglet diets and allow the energy level of the diet to be reduced.
Particle size
Particle size can also be considered in post-weaning diets. Feed particles above 1.5 mm will improve gastric retention, acidification of the stomach and a low nutrient release rate from the stomach to the intestine, improving nutrient digestibility after weaning (Molist, 2022). Previous research reported that a coarse feed, such as wheat bran, helps to reduce the likelihood of DPD in part due to its physico-chemical properties (Molist et al., 2010, 2012).
Lactose
Lactose is an ideal energy source for weaned piglets and has a positive effect in terms of feed intake (Zhao et al., 2021). However, some research shows that it may be useful to reduce the level of lactose in the diet if there is a challenge of diarrhoea (Zhao et al., 2021). The latter seems to increase the dry matter content of the faeces without having a significant detrimental effect in terms of performance (Zhao et al., 2021).
Feed additives
Additives could also be considered for post-weaning challenges. There is a wide range of feed additives on the market that claim to have a positive effect in terms of promoting gut health and reducing the incidence of DPD. Acidifiers have long been used in weaner diets to help control the bacterial population (Bonetti et al., 2021). Commercially available acidifiers often represent a combination of organic and inorganic acids, as they can act synergistically. The magnitude and consistency of the response to acidification can be influenced by factors such as acid form, inclusion rate and diet composition (Jacela et al., 2009). Prebiotics and probiotics can help mitigate DPD. However, the differences observed in the literature mean that more research is needed to understand the impact of their positive effects as antimicrobials and modulators of the animal immune system (Bonetti et al., 2021).
Feeding during the maturation phase
Diets after the first post-weaning period, known as the acute phase (5-10 days), shift the focus towards improving the productive performance of pigs while maintaining gut health. In this second period, known as the maturation phase, it is possible to start increasing the Lis DIE to energy ratio by increasing crude protein but also synthetic amino acids, changing the inert/fermentable fibre ratio by decreasing inert fibre levels and adding more fermentable fibres, and maintaining a low ABC-4 and structure in the feed (Huting et al., 2021).
Pre- and post-weaning feeding strategies
Pre-weaning strategies should be considered to improve piglet adaptation to the post-weaning environment. Ensuring good feeding of sows during gestation and lactation, good colostrum and milk intake of piglets, good management of hyperprolific sows and providing complementary feeds to piglets during the lactation phase, such as milk replacer or creep-feed, will help to improve piglet weaning weights and better adaptation to the post-weaning period (Blavi et al., 2021; Huting et al., 2021; Pluske, 2016). Feed intake can be improved by feeding the same or a similar diet before and after weaning (Huting et al., 2021). Also, different feeding strategies could be followed to improve post-weaning feed intake and reduce morbidity and mortality (Wensley et al., 2021b, 2021a). Mat feeding and mash feeding are strategies that can help pigs to start eating as soon as possible after weaning. It is also important that they have a sufficient length of feed trough, with temporary incorporation of dishes or feeding directly into the solid area of the pen, so that they can eat at the same time, giving feed several times a day. See the PIC® wean-to-finish manual for more information. Finally, the use of an electrolyte solution can be useful to activate and stimulate the appetite of the piglets by attracting them to the feeder.
In summary…
There is no single management and/or nutritional strategy that will greatly reduce the incidence of DPD. Therefore, a holistic approach is needed to be successful (Figure 1 and Figure 2).
Figure 1. Management strategies and main factors to consider pre- and post-weaning
Figure 2. Nutritional strategies and main factors to consider before and after weaning (based on Molist et al. 2022).
