Effects of tannins on post-weaning diarrhea and growth performance of weaned piglets

Han Quang Hanh¹, Duong Van Toi², Le Van Khoa², Ha Xuan Bo¹, Frederic Farnir³ and Do Duc Luc¹,

¹Faculty of Animal Science, Vietnam National University of Agriculture, Hanoi, Vietnam

²Anh Duong Khang Nutrition Company, Ho Chi Minh city, Vietnam

³Faculty of Veterinary Medicine, University of Liege, Belgium

ddluc@vnua.edu.vn

Abstract

This study was aimed to evaluate the effects of tannin supplementation on post-weaning diarrhea and growth performance of weaned piglets. A total of 81 Duroc x (Landrace x Yorkshire) piglets at age from 27 to 42 days were randomly allocated to the control group (CON) and treatment group with 0.25% tannin blend supplemented to the basal diet (TAN). The experiment lasted for 30 days from weaning. The body weights were recorded at weaning (IBW) and at finishing period (FBW) to calculate the average daily gain (ADG). The diarrhea was identified by scoring fecal consistency two times per day. Diarrhea rate of piglets in CON was 3.014 times higher than that in TAN. Increasing one kilogram of IBW led to a decrease of 0.841 times in diarrhea rate. FBW and ADG in TAN were higher than those in CON (P<0.01). These results suggest that tannin supplementation at 0.25% helps prevent post-weaning diarrhea and improve ADG in weaned piglets. Increasing body weight at weaning also reduces diarrhea rate. Further studies should be carried out to estimate the optimal tannin supplementation level in the diet for weaning piglets.

Keywords: plant extraction, piglet, disease, growth rate

Introduction

Weaning is one of the most susceptible periods when piglets are very sensitive to many substantial nutritional, physiological, environmental, and social challenges, causing a high proportion of post-weaning diarrhea and poor growth performance or even death. The nutritional change from milk to solid feed causes a decline in the colostrogenic immunity and the disappearance of lactogenic immunity (Fu et al., 1990; Poonsuk & Zimmerman, 2018). In the meantime, the immature gut, impaired intestinal epithelial barrier function, and undeveloped mucosal-immunity (Gresse et al., 2017; Moeser et al., 2017; Pluske et al., 2018) make these organs more susceptible to the pathogen agents that can cause diarrhea. In addition, the changing environment from farrowing pens to weaning pens, where piglets are mixed with unfamiliar pigs, may introduce them to some new pathogens. The post-weaning diarrhea may have negative effects on growth performance of pigs and the economic efficiency of pig production sector. Therefore, finding an effective strategy for prevention of post-weaning diarrhea is a need.

Various strategies to prevent post-weaning diarrhea in piglets have been studied and applied to reduce the use of antibiotics in pig industry. Canibe et al. (2022) reported that the major feed strategies for post-weaning diarrhea prevention include changes in feed ingredients, feed additives, or feed forms, but that the efficacy of these measures depends on many factors including the animal health status and the dose and composition of the feed. Among these strategies, the use of plants and plant extracts is considered as a promising method that can alter antibiotics and zinc oxide use for post-weaning diarrhea prevention in piglets (López-Gálvez et al., 2021). The supplementation of botanicals or their extract may have both antimicrobial effects and immune-regulating and antioxidant effects (Yang et al., 2015).

Tannins are known as a traditional medicine for chronic diarrhea treatment in human (Lewis & Elvin-Lewis, 2003) and animals thanks to their antimicrobial, antioxidant and anti-inflammatory effects (Huang et al., 2018). Tannins are polyphenolic compounds and classified as hydrolysable or condensed (Ma et al., 2021) and also complex tannins (Canibe et al. , 2022). Tannins are commonly found in many plants, including forages, cereals, medical herbs, fruits (banana, blackberry, apple, grape, etc.), tea (Salunkhe et al., 1982; Wang et al., 1999, Nonaka et al., 1984; Bravo et al., 1992; Mertz et al., 2007; Mercurio and Smith, 2008; Kheng, 2010) cited by Huang et al. (2018). Several studies have demonstrated the efficiency of tannins in diarrhea prevention in piglets (Liu et al., 2013; Girard et al., 2018; Dell’anno et al., 2021), but the sample sizes in these studies were very low and few in vivo studies reported directly about effects on post-weaning diarrhea  (Huang et al. , 2018). Our study aims to evaluate the effects of tannins supplementation in the diet on post-weaning diarrhea and growth performance of weaned piglets.

Materials and Methods

Experimental design

This study was carried out at a commercial pig farm in Dong Nai province, South of Vietnam, from September to October 2022. A total of 81 weaned DLY piglets from Duroc boars and hybrid sows (Landrace ×Yorkshire), including 31 females and 50 castrated males aged 27 to 42 days, were used.

On weaning day, we identified each individual animal using ear tags and we weighed them to obtain their initial body weight (IBW). The animals were randomly allocated to 3 pens (27 piglets per pen). One pen was a control group where piglets were fed basal diet (CON). Two other pens were treatment group (TAN) where animals were fed basal diet supplemented with 0.25% tannin blend (Silvafeed Nutri P) produced by Silvateam Italy and distributed by Anh Duong Khang company.

The powder blend used in this experiment contained 75% tannins extracted from Chestnut wood (Castanea sativa) by hydrolysable ellagitannins using hot water. Two types of feed were provided to the piglets, including commercial feed in pellet form (ME 3,200 Kcal/kg, crude protein 20%, lysine 1.2%, calcium 0.5-0.8% and phosphorus 0.4-1.5%) and on-farm mixed feed in powder form (ME 3,500 Kcal/kg, crude protein 19%, lysine 1.2%, calcium 0.5-0.8% and phosphorus 0.4-1.5%). The tannin blend was added to the powder feed during feed processing in the farm. For the first 20 days of experiment, 70% commercial feed was mixed with 30% on-farm mixed feed. The last 10 days for this study, proportion of commercial and on-farm mixed feed was 60% and 40%, respectively. The feed was supplied 2 times per day (at 07:30 and 14:00) with 130g per day for a piglet at the first 3 days and then increasing up to 400g in the end of experiment. Before our study, diarrhea was observed on the weaning pigs in all pens on the farm.

The diarrhea status was recorded individually for each piglet every day at 09:00 and 15:00. All piglets were checked one by one at each pen during 30 experimental days. The health status of each animal was registered according to method of Thomas et al. (2021) based on scoring grid, including D0 = normal state – healthy animals, D1 = onset of diarrhea – soft feces, D2 = marked diarrhea – liquid feces. Animals with scores D1 and D2 were considered diarrheic. The data was cumulated for 30 experimental days. Diarrhea rate was calculated based on method of (Yu et al., 2020) as follows: diarrhea rate (%) = total cumulated number of piglets with diarrhea divided by total cumulated number of piglets and multiplied by 100.

At the end of the experiment, the body weight was recorded individually as final body weight (FBW). Average daily gain (ADG) was calculated based on FBW, IBW and duration of the experiment. Feed to gain ratio was calculated using a cumulative feed intake during the experiment and body weight gain. As pigs were fed in a group, only one observation of feed to gain ratio was calculated for each treatment.

Statistical analysis

The effect of tannin supplementation on the diarrhea rate was assessed using logistic regression. Four fixed factors (tannin supplementation, sex, weaning age and body weight at weaning) were included in the initial model. The backward method was applied to remove the non-significant effects (P=0.15). The final logistic regression model is:

log[p_i /(1– p_i)] = β₀ + β₁×TA + β₂×IBW

Where p_i = probability of a diarrhea if piglet i (0 = healthy and 1 = diarrhea), b₀ = intercept, TA = effect of tannin supplementation (CON and TAN), IBW = body weight at weaning, β₁ and β₂ = slopes for TA and IBW respectively. Odd ratio (OR) was calculated to compare the effect of treatment (CON and TAN) on diarrhea rate.

Data on growth performance was analyzed using the following statistical model. The weaning age varied among piglets and was therefore added in the model as a covariate.

y_ijkl = m + TA_i + S_j + b*D_k + e_ijkl

Where y_ijkl = variable of growth performance (IBW, FBW and ADG), m = overall mean, TA_i = effect of tannin supplementation (CON and TAN), S_j = effect of sex (female and castrated male), b = regression coefficient, D_k = covariate effect of weaning age, e_ijkl = residual. Number of observations (n), least square mean (LSM) and standard error (SE) are presented in the result section. Pairwise comparisons between LSMs were made using Tukey test and considered statistically significant when P<0.05. All analyses were performed using SAS® OnDemand for Academics.

Results

During the experiment, 12 out of 81 piglets died including 4 for CON and 8 for TAN. The mortality rate was 14.81% for both groups. The cumulative data of diarrhea and non-diarrhea piglets in CON and TAN during 30 days of experiment is shown in Table 1. The diarrhea rates were 15.39% and 5.14% for CON and TAN, respectively.

Table 1. Effect of tannin supplementation on diarrhea rate in weaned piglets

In each cell, the first value is a cumulative observed count and the second value in parentheses is a diarrhea rate

The regression parameters of tannin supplementation and BWW were 1.1034 and -0.1737 respectively (Table 2). Diarrhea rate in DLY piglets was significantly affected by tannin supplementation (P<.0001) and BWW (P=0.0043). The diarrhea rate of DLY piglets in CON was 3.014 times (95% confidence interval: 2.223 to 4.087) higher than that in TAN (Table 3). Similarly, increasing one kilogram of IBW led to a decrease of 0.841 times (95% confidence interval: 0.746 to 0.947) in the diarrhea rate (Table 3).

Table 2. Estimated parameters from logistic regression

Table 3. Odds ratio estimation (OR)

The effects of tannin supplementation and sex on growth performance of DYL piglets are shown in Table 4 and 5, respectively. Coefficient of determination (R²) for IBW, FBW and ADG were 0.14, 0.13 and 0.14, respectively. The weaning day was also correlated to IBW (P=0.0082), while did not affect FBW (P=0.4974) and ADG (P=0.0838). FBW and ADG were significantly higher (P<0.01) in TAN compared to those in CON (, table 4). Inversely, IBW, FBW and ADG were observed similarly (P>0.05) between females and castrated male pigs (Table 5).

Table 4. Effect of tannin supplementation on growth performance of DYL piglets

Within a row, LSMs followed by different letters are significantly different (P <0.05)

Table 5. Effect of sex on growth performance of DYL piglets

During 30 days of the experiment, the body weight gain was142.6 and 56.9 kg for TAN and CON respectively. The total feed intake was respectively 388.9 and 179.6 kg. Consequently, feed to gain ratio was 2.73 and 3.15 kg for TAN and CON, respectively. The feed to gain ratio of TAN was lower than that of CON but we did not make a statistical comparison due to the limitation of observation.

Discussion

Post-weaning diarrhea is still a challenging syndrome that may have a significantly negative impact on pig production. According to the calls for a reduction of antibiotic use in pig industry, alternative strategies such as botanicals are increasingly investigated in post-weaning diarrhea prevention. In our study, tannins, a compound commonly found in many plants, were effective in post-weaning diarrhea prevention and piglet growth performance. The proportion of piglets affected by diarrhea was lower when tannins supplemented in their diet. This result is consistent with previous studies. Girard et al. (2018) reported that supplementation of 1% chestnut extract significantly reduced diarrhea incidence and duration in piglets. Song et al. (2021) found that 0.05%, 0.1%, 0.2% or 0.4% of tannic acid supplements in the diet of weaned piglets linearly reduced the diarrhea rate and diarrhea index. Tannins have a wide range of effects on inhibiting or slowing down of diarrhea-related pathogens. Girard & Bee (2020) summarized the effects of tannins on prevention of microbial infections, including the prevention of bacterial adhesion to intestine, inhibition of bacterial enterotoxins and channels in electrolytes and water secretion into the lumen, and the prebiotic effects in the gut that benefit the resistance ability of animals to diarrhea-related pathogens. In our study, the hydrolysable tannins were used and this form was demonstrated to inhibit the total activity of ceacal bacteria (Bee et al., 2017).

The effect of tannic acid on diarrhea in piglets depends on its dose in the diet. In our study, at the dose of 0.25% of tannin, the diarrhea percentage was 5.14% during 30 days of experiment. This is consistent with previous study by (Song et al. , 2021) who reported 7.34% of diarrhea rate at 0.2% of tannic acid dose during 28 days of experiment. An increase in the dose of tannic acid in the diet linearly decreased the diarrhea rate (Song et al. , 2021), but it may have negative impacts on growth performance due to the affinity with proteins, digestive enzymes, and polysaccharides in monogastric animals (Mueller‐Harvey, 2006; Viveros et al., 2011; Ebrahim et al., 2015) unless more than 1% of tannic acid supplemented their diets (Rezar & Salobir, 2014).

Although tannins are known as an anti-nutritional factor (Pathaw et al., 2022), in some cases, especially with appropriate dose, they may have positive effects on pig performance. In this study, supplementation of 0.25% tannins in the diet improved the average daily weight gain. This is similar to a previous study that reported that 0.45% hydrolysable tannin supplementation help increase ADG of piglets (Biagi et al., 2010). Similarly, (Girard et al., 2020) found that 2% of hydrolysable tannins/condensed tannin supplementation increased the ADG of piglets. According to Caprarulo et al. (2021), the mechanism for improving pig performance by tannin supplementation is not fully understood, but literature data indicates that low (<1%) or medium (≥ 1-2%) dietary tannin benefited growth performance of post-weaning piglets. In this study, we used a low tannin dose and thus it resulted in an improved ADG of piglets compared to those in the control group.

In our study, increasing body weight at weaning led to a reduction in the diarrhea rate in weaning piglets. The study of Richard et al. (2013) confirmed that diarrhea rate was consistently associated with body weight. Pigs with lower weight had a higher diarrhea rate. Body weight at birth below 1.1kg increased diarrhea rate by 2.3 times (Eriksen et al., 2021). Improvement of body weight at weaning could also be a solution to reduce post-weaning diarrhea in pig production.

Conclusions

The supplementation of tannin at 0.25% dose in the diet had a positive effect on diarrhea incidence and average daily gain of weaned piglets. An increase in body weight at weaning also reduced the diarrhea percentage of pigs. Further studies should be conducted with different levels of tannins supplementation in weaned piglets to identify the optimal dose that benefits post-weaning diarrhea while having no negative impacts on growth performance.

Acknowledgments

Tannin blend used in this research was provided by Silvafeeds company. The authors acknowledge the staff and manager of the commercial pig farm in Dong Nai province for their contributions.