While many farmers do not use antibiotics in finishing and sow rations, starting newly weaned pigs with developing immune systems and changing intestinal tracts can be a challenge. Much research has been conducted looking at different methods for starting pigs to prevent enteric challenges and overcoming systemic pathogens. Recently, work is also focusing on ingredients that can be added to both sow and finishing diets to improve gut health and minimize pathogen transmission. The goal of today’s discussion is to focus on processes and nutritional programs to maintain good animal growth/reproduction performance and animal health while using antibiotic-free programs.
The use of antibiotics in the livestock industry has been in practice for many years. The evolution of antibiotic-free (ABF) production has been directed both by the consumer and the health industry. Over the last 20 years, discussions on antibiotic resistant organisms in human medicine have evolved into the livestock industry to help control potential bacterial resistance over time across all species. In addition, recent consumer groups have also started to request that meat animals not be fed antibiotics during the course of their growth which is motivated by personal health, taste, quality and environmental concerns. While we acknowledge that for animal welfare, antibiotic intervention does need to be available to help control an illness, many producers are working towards either further reducing their use of antibiotics or raising a majority of their animals as ABF to meet the demands of the public.
The definition of antibiotic-free (ABF) has many different versions. While animals cannot go to harvest if they have not had proper antibiotic withdrawals to minimize antibiotic residue detection potential, two other classifications of ABF currently exist. The first classification would be that of no antibiotics will be allowed after the pig is weaned from its mother. The second classification is defined as the “never-ever” category. Never-ever refers to the fact that the pig is never given an antibiotic during the course of its lifetime. In the United States today, both classifications of ABF are used for different markets.
In Canada, the Canadian Food Inspection Agency (CFIA) website states: “In order to display the claim raised without the use of antibiotics, the animal or fish must not have received antibiotics from birth to harvest. In addition, no antibiotics can be administered to the mother of the animal in question in any manner which would result in antibiotic residue in the animal. Vitamins and minerals given to the animal may only be given at the level of physiological action for dietary supplement, not for antimicrobial effect.”
Defining the cost of antibiotic-free
While there have been a few studies conducted that show the potential impact of ABF programs in production, the results are quite variable. According to Vansickle (2011), Dr. Main demonstrated that antibiotic-free production in the United States could cost on average US$11/pig and go as high as US$15.50 considering 70% of the barn will go to finishing as antibiotic-free.
Given that herd health and stability are major variables in swine production, the cost of ABF production would likely be highly variable even within a system. A 70% program completion rate could be easily achieved in some barns, but a major challenge in others. In 2008, an article was published at the American Association of Swine Veterinarians conference demonstrating that a facility can achieve equal reproductive performance and have minimal reductions in wean to finish performance without the use of antibiotics and animal proteins (Kohler et al., 2008). With the opportunity to capture an ABF premium, the producers were able to only have an increase in production costs of $0.32/head compared to the estimated European value of $5.24 at the time. While the data is not conclusive, what is conclusive is that good initial health and vaccine programs are keys to making the programs effective.
Defining problems and solutions in achieving antibiotic-free
In the past, antibiotics have been used generally for one of three purposes: 1) to treat or manage disease, 2) to prevent disease, and 3) to improve feed efficiency.
Whether a system chooses to have an ABF program or continues to use antibiotics to control disease, the focus of all swine farmers is to minimize the use of antibiotics and to prevent disease. There are four key areas associated with the practice of good animal health. These areas include: health programs, management, genetics, and nutrition.
Animal health programs and management practices go hand-in-hand. Animal caretakers must implement and effectively follow health programs outlined by the herd veterinarian. Herd veterinarians will establish vaccine strategies to minimize disease outbreaks and develop sanitation programs to reduce the spread of disease (biosecurity). Animal caretakers must carefully follow these programs as well as establish good biosecurity programs and sound rodent control. In addition, animal caretakers need to evaluate the animal facilities and maintain those facilities as part of routine maintenance and upkeep. Ventilation needs to be established by phase to reduce drafts on small pigs and also minimize any manure gases that may reduce performance. Selection of robust genetics that can tolerate a variety of environmental parameters will also improve the success of an ABF program.
Nutrition programs can have a significant impact on pig performance. In addition, ingredients other than antibiotics can be added to diets to help control or mitigate potential health challenges as the pig grows. In order to be effective in developing a nutritional program, nutritionists need to communicate with the farmer or the veterinarian to further understand the health status of the pig and also identify times during the piglet’s growth phase where health challenges may arise. While there are many ingredients on the market that claim to aid in gut health, digestion, feed efficiency, and feed intake, understanding the mode of action and expected outcome will aid in the nutritionist’s decision process.
At weaning, the gut of the piglet goes through dramatic changes as the pig transitions from liquid feed to dry feed. Even in systems that maintain liquid feeding, the physiology of the gut changes in response to the weaning process. The focus the first 3 weeks after weaning is to transition pigs rapidly to their new food source and maintain a healthy gut and immune system to help the pig counter any pathogens that may be present as the maternal antibody declines.
Gut health for the weaned pig is an area that has been researched for many years. However, the dynamics of gut immunity, gut enzymes, and the microflora interactions are not well understood. Establishing a good population of beneficial gut bacteria that aid in digestion and reduce pathogenic bacteria balances around pH and substrates. Enzyme production is mainly that of lactase while other carbohydrase enzymes will increase through week 8 of age. Diets that are high in non-digestible feedstuffs allow significant nutrients to gut microflora, which increases for the potential of pathogens to overtake population and cause disease. Feeding highly digestible starches in early rations have been shown to improve gut health. In addition, in a series of studies conducted by Pettigrew and his research team, various plant extracts have also been shown to be beneficial in improving intestinal villi length and reducing pathogenic bacteria. The use of probiotics to maintain a certain population of microorganisms has been shown to be beneficial. In addition, the use of lactose to lower the pH and maintain Lactobacilli has also been shown to improve pig performance.
As the piglet reaches 6 weeks of age, maternal antibodies start to decay and the pig reaches a susceptible period for health challenges. Song et al. (2012) demonstrated that using egg antibodies can improve general health in populations of pigs with unspecified health status. While growth performance has been shown in some studies to be similar to spray-dried plasma (SDP), SDP has additional benefits in improving immune function (macrophage modulation) and cell junctions (Campbell et al., 2010).
Many farmers focus on minimizing late finishing pig mortality and feed efficiency. A recent study reported that enzymes (such as xylanase) have the potential to improve pig viability from 3.99% to 2.39% and improve gain:feed from 0.286 to 0.290 by converting arabinoxylans to xylo-oligomers which can shift the microflora to favor the beneficial organisms (Zier-Rush, 2016). In addition, Greiner et al. (2016) demonstrated that feeding 150 ppm of supplemental copper in late finishing improved gain:feed from 0.31 to 0.34. Sometimes, altering the feedstuffs can improve the health of the pig in the face of a health challenge.
For many years, the human health groups have discussed the isoflavones and other beneficial components of soybeans. Data from Greiner et al. (1999) and Rochell et al. (2015) demonstrated that feeding either isoflavones directly or higher levels of soybean meal to pigs in the face of a PRRS infection can reduce viral replication and improve performance.
While much research has demonstrated that antibiotics can improve feed efficiency, there are also mechanical, genetic, environmental, and nutritional modifications that can also improve feed efficiency. In Table 1, as particle size reduces from 650μm to 350μm, finishing average daily feed intake decreased and gain:feed increased. Pelleting feed resulted in improved average daily gain.
However, pelleting 350μm corn (maize) versus 650μm corn showed no additional benefit (Nemechek et al., 2016). Other studies have demonstrated on average a 4-8% improvement in both average daily gain and feed efficiency when diets are pelleted in grow finish (Miller, 2012).
In addition, other factors can influence feed efficiency. Animals housed in an environment above or below their thermal neutral zone can have poorer rates of feed conversion. The health status of the animal can also alter feed efficiency and growth rate, as well as, genetics, and microbial loading of the environment.