In many countries sub-therapeutic usage of antibiotics (AGPs) is still widespread. According to the Trade and Agriculture Directorate Committee for Agriculture, the livestock sector’s consumption of antimicrobials is projected to rise by 67% between 2010 and 2030, reaching 105,600 tons annually. Meanwhile, the sales of novel growth promoters should rise by at least 120 percent over the same period according to our own calculations, albeit from a different base.
Brakes on antibiotic usage
At least 32 countries have imposed a nationwide ban on antibiotic growth promoters and 35 have a veterinary prescription requirement. In some areas, efforts such as the European Union’s 2006 ban on the use of antibiotics as growth promoters in animal feed, has led to a decline in sales.
Furthermore, scientific research suggests that the farm level benefits have peaked. A meta-analysis of more than 1,000 swine trials between 1950 and 1985 did show average daily gain (ADG) and feed conversion ratio (FCR) improvements of 16.4 percent and 6.9 percent, respectively, in rearing pigs.
A new study by Teillant and Laxminarayan (2015) corroborates these findings, but reveals that since 2000, in-feed antibiotics elicit only minor responses in pig performance indicators through different production stages. The authors suggest several possible explanations. First, AGPs may have a reduced impact when animal nutrition, hygiene, genetics and health status of the animals are optimal. Second, resistance to antibiotics may play a role in diminishing the effectiveness of AGPs. This coincides with an increase in recommended dosage levels of sub-therapeutic antibiotics over the past decades.
Figure 1. Improvement in feed conversion ratio of pigs fed with antibiotics.
Source: Aude T. & Ramanan L., 2015
New ways to promote growth
Replacing AGPs will rely upon a holistic approach to improve animal health status and performance through better management, biosecurity measures, vaccination programs, diagnostics and feeding strategy.
Since feed costs account for a significant part of total production costs, feeding strategy is a crucial point. Organic acids, phytogenics, probiotics and prebiotics have all been identified as potential in-feed antibiotic replacements.
Novel growth promoters’ (NGPs) mode of action differs considerably from antibiotics. While phytogenic feed additives (PFAs or botanicals) tend to improve digestion and an animal’s anti-inflammatory and anti-oxidative status, organic acid-based products have a clearer antimicrobial effect that supports feed and water hygiene and the control of Gram-negative bacteria. For example, probiotics, or direct-fed microbials (DFM), serve to reinforce a healthy gut microbiota. All of these categories of feed additives are expected to grow more quickly than in-feed antibiotics in the coming years.
Comparable or better results
Significant effort has been paid to identifying which additives will replace AGPs. In general, a replacement should perform roughly equally as well under practical conditions in order to gain acceptance.
Looking across nine swine trials performed in various countries worldwide and testing both AGPs and NGPs (phytogenics or organic acid-based products) at a variety of production stages, each NGP group performed better on average in terms of FCR and ADG compared to the AGP group (Figures 2 and 3). This improvement accompanies better gut health and fewer intestinal disorders.
Figure 2. Average FCR results of nine pig trials.
Source: BIOMIN, 2015
Figure 3. Average ADG results of nine pig trials.
Source: BIOMIN, 2015
In the above trials both AGP and NGP groups performed better than control groups. In seven trials of antibiotics and phytogenic feed additives, PFAs delivered a 5.47% improvement in FCR compared to AGPs. In two trials of antibiotics and organic acid-based products, acidifiers offered just a one-half percent improvement in FCR. This suggests that NGPs are appropriately suited to replace AGPs in terms of feed efficiency. Both antibiotics and certain phytogenics reduce inflammation within animals, generating energy savings that can be used for growth. Acidifiers work differently in that they contribute to feed and water hygiene and decrease the overall pathogen load in the gastrointestinal tract. FCR improvement matters considerably since feed costs account for around 70% of total swine production costs. Higher efficiency—meaning a lower FCR—means better profitability. Improving the FCR from 2.75 to 2.70 of weaner to finisher (8-110 kg) stages means around 5 kg less feed per pig, which reflects 5 tons feed savings per 1000 pigs produced.
In seven trials of antibiotics and phytogenic feed additives, pigs receiving the PFA had a 6% higher daily gain on average compared to those receiving AGPs. In two trials of antibiotics and organic acid-based products, pigs receiving acidifiers had a 10.8% higher daily gain on average compared to those receiving AGPs. Improvement of average daily gain (ADG) can positively influence the final weight of the animals and number of rotations. For instance, an ADG improvement in growing-finishing phase from 900 to 910 grams can result around +0.9kg extra weight for finishers at sale. The above trials indicate that NGPs can also be considered an appealing tool to improve performance parameters.
Identifying the right tool
The results suggest that performance can be maintained with novel growth promoters and that these can be considered an important tool in antibiotic reduction strategies. The aim of NGPs should always focus on disease prevention, not treatment. Species, production phase, farm conditions, product dosage and ROI considerations all influence the choice of feed additive. Furthermore, combinations of additives have been demonstrated to work successfully in particular situations to achieve specific objectives or to counter challenges such as mycotoxins or pathogenic bacteria. This means that organic acid-based products and phytogenic feed additives may each play a role in future production as part of a tailer-made solution to help producers achieve animal health and performance goals.