Reducing AGPs: Insights from research in Vietnam
24 June 2020
Author: Nienke de Groot (Global Gut Health Programme Manager Swine)
Reviewed by: Morvarid Rezvani – (Product Manager – Selacid Green Growth) (sorry if I missed someone).
By Nienke de Groot (Trouw Nutrition, Global Gut Health Programme Manager Swine)
While there is widespread agreement that the use of in-feed antibiotics as antibiotic growth promotors (AGPs) needs to be reduced because of consequences for animal and human health, achieving this aim worldwide, including in regions such as Asia, has proven difficult.
Since African Swine Fever erupted in China in mid-2018, the global pork industry has been fixated on the threats posed to stakeholders across the feed-to-food chain. In 2019, ASF spread to Vietnam and neighboring markets in Southeast Asia. Due to production losses associated with the endemic situation of ASF in Asia, and subsequently restrictions on movement, pork prices have surged as much as 47% year-over-year.
Figure 1 and 2
from: African Swine Fever: A global update. Rabobank Food & Agribusiness, 2020
As Vietnam's economy and population grows rapidly, production and consumption of animal protein is increasing even faster. Due to the country's ban on AGPs, alternatives are being used to reduce the ban's impact on mortality, growth performance and FCR.
AGPs and diminished returns in studies
Multiple studies conducted since 2000 suggest that productivity gains from antibiotic growth promotors (AGP) in swine production are lower compared to results seen in earlier studies. For example, it was reported that the use of AGP in grower-finisher pigs increased average daily gain by 0.2% and feed efficiency by 0%, which is much lower than reported in the 1980s (4.2% and 2.2% respectively) (Laxminayaran, 2015). Possible reasons for the reduction in growth response may be optimisation of production conditions in the swine industry, or an increasing level of resistance of bacteria to certain types of antibiotics. These tendencies stimulate a search for effective products and ingredients to replace AGPs and support performance of growing finishing pigs.
Table 1. Efficacy of antibiotic growth promoters for pigs, early and recent studies (Laxminayaran, 2015).
Early studies: data from 453, 298 and 443 experiments, involving 13,632, 5,783 and 13,140 pigs for the three phases, respectively. Dritz, 2002: Data from five and four experiments, involving 3,648 and 2,660 pigs, for the nursery and grower-finisher phases, respectively. NSS = not statistically significant.
Reducing infection pressure without AGPs
Trouw Nutrition has conducted extensive scientific and commercial research on the prevention of dysbiosis and the modulation of microbiota in pigs. Blends of small chain fatty acids and medium chain fatty acids have proven to be effective in stomach pH reduction and lowering the level of potential pathogens in the gastro-intestinal tract, thus supporting the microbial balance. A combination of short chain fatty acids (SCFA) for a Gram-negative antimicrobial effect, and a blend of medium chain fatty acids (MCFA) for a Gram-positive antimicrobial effect creates an effective tool in reducing infection pressure for both Clostridium perfringens (Gram-positive bacteria) and E. coli (Gram-negative bacteria).
A study was performed at the National Institute of Animal Science, Vietnam, to investigate whether an AGP alternative could support growth performance of growing-finishing pigs in a commercial setting. A total of 312 grower pigs (Yorkshire × Landrace × Duroc) were allocated randomly to three treatments consisting of 8 replicate pens (3 pens male, 5 pens female) with 13 pigs each. An AGP-free corn-soy based diet was formulated (basal diet) and dietary treatments included: basal diet (negative control), basal diet with Colistin at 20 ppm (positive control), basal diet with Selacid® Green Growth, a synergistic blend of free and buffered short chain fatty acids combined with a blend of medium chain fatty acids. The diets consisted of two phases; the grower phase from 25-60 kg body weight and finisher phase from 60-100 kg body weight.
Overall, the dietary supplementation of Selacid Green Growth showed a similar effect compared to the AGP on all growth parameters measured. Compared to the negative control group, Selacid GG significantly improved the final body weight (+3.4 kg; 3.5%), ADG (+39 g/day; 5.0%) and FCR (−20.2 points; 7.4%) (p < 0.05, Figure 3). The male pigs given Selacid GG had the highest final weight compared to male (+1.8 kg) and female (+6.6 kg) pigs fed negative control and female pigs given AGP (+2.7 kg) diets (p < 0.05, Figure 4).
Lower levels of multi-drug resistance seen in growing and finishing phase
As noted earlier, one potential reason for the reduction in growth response to AGP in the last years suggested by Laxminayaran et al (2015) is an increasing level of resistance of bacteria to certain types of antibiotics. Fecal analyses from the trial executed in Vietnam show that the E. coli strains isolated from the faecal samples were multi-drug resistant, meaning the bacteria showed resistance to different types of antibiotics. The percentage of E. coli resistant to different types of antibiotics during the growing and finishing phase was significantly reduced by supplementation of Selacid Green Growth in the diet, compared to the positive control group.
Figure 3. Overall effect of treatment on performance of grow-finish pigs in different treatments from d1-90. Bars with different superscripts differ (p < 0.05)
Figure 4. Average final body weight (83% confidence interval as error bars) of grower-finisher pigs of different treatment groups on d90. Bars with different superscripts differ (p < 0.05).
Considering the economic potential of AGP alternatives
Blends of SCFA-MCFA have been broadly applied worldwide with reasonable success. Positive effects of blends of organic acids are associated mainly with increased gastric acidity, antibacterial activity, reduced coliform populations, and improved digestibility, resulting in an improvement in performance and feed efficiency of fattening pigs.
Results from current study implicate that Selacid Green Growth is effective in improving growth and feed efficiency of grower-finisher pigs. Both female and male pigs are benefiting from the use of Selacid Green Growth in their diets. The results suggest that Selacid Green Growth can be used in AGP-free production to achieve significant growth performance improvement in grower-finisher pigs. The improvement in body weight from using Selacid Green Growth, combined with a numerical reduction in mortality resulted in an added value of € 5.48 per pig. Comparing to the AGP treatment, the added value was € 1.32 per pig. These added values prove that the use of Selacid Green Growth is an economically viable option in an AGP-free production system, which can support producers in Asia during these challenging times.