No Antibiotic Ever (NAE) Versus Conventional Broiler Production: It’s Complicated

Broiler production has evolved significantly over the years to meet a constant growing demand for animal protein. Rooted on major advances in genetics, facilities and environmental conditions, management, and specially, in nutrition and health, the U.S. broiler industry improved tremendously in productivity and efficiency, clearly demonstrated by a marked reduction of the average market age (i.e., days to market), while significantly increasing average market weight, breast meat yield and feed efficiency (National Chicken Council, 2023). For decades, conventional broiler production was dominant, with extensive use of antibiotics to promote growth and manage disease challenges (prevention and control). However, concerns over the excessive use of antibiotics in conventional broiler production raised questions about its impact on public health, regarding the increasing occurrence of antimicrobial resistance. Increasing consumer pressure combined with different marketing strategies adopted by key players in the U.S. poultry industry to differentiate and capture higher value promoted the rapid emergence of different production approaches, resulting in a variety of “negative labels” for their final products reaching consumers, such as: Grown without antibiotics, raised without antibiotics, humanely raised without antibiotics, no antibiotics, no added antibiotics, raised without added antibiotics, no antibiotics important for human medicine, no medically important antibiotics, no human antibiotics, no antibiotics ever, and others. However, what started as a marketing differentiation strategy quickly became widespread and common in the industry. Consequently, the economic viability of broiler production without the use of antibiotics has become a subject of ongoing debate and analysis within the poultry industry, with some producers switching back to the practice of using antibiotics (some categories, such as antibiotics not important in human medicine). However, this type of analysis is never easy or straightforward, as a multitude of factors should be taken into consideration. Here, we attempt to discuss two contrasting broiler production systems, conventional versus no antibiotic ever (NAE), as they represent both ends of the spectrum, regarding the use of antibiotics or no use at all being allowed. The discussion is focused primarily on differences in animal health, growth performance, and food safety. Other areas, such as economics and sustainability are outside the scope of this discussion, but will briefly be touched on, as ultimately, both are directly impacted by the main topics of focus

No Antibiotic Ever (NAE) Versus Conventional Broiler Production: It’s Complicated

Broiler production has evolved significantly over the years to meet a constant growing demand for animal protein. Rooted on major advances in genetics, facilities and environmental conditions, management, and specially, in nutrition and health, the U.S. broiler industry improved tremendously in productivity and efficiency, clearly demonstrated by a marked reduction of the average market age (i.e., days to market), while significantly increasing average market weight, breast meat yield and feed efficiency (National Chicken Council, 2023). For decades, conventional broiler production was dominant, with extensive use of antibiotics to promote growth and manage disease challenges (prevention and control). However, concerns over the excessive use of antibiotics in conventional broiler production raised questions about its impact on public health, regarding the increasing occurrence of antimicrobial resistance. Increasing consumer pressure combined with different marketing strategies adopted by key players in the U.S. poultry industry to differentiate and capture higher value promoted the rapid emergence of different production approaches, resulting in a variety of “negative labels” for their final products reaching consumers, such as: Grown without antibiotics, raised without antibiotics, humanely raised without antibiotics, no antibiotics, no added antibiotics, raised without added antibiotics, no antibiotics important for human medicine, no medically important antibiotics, no human antibiotics, no antibiotics ever, and others. However, what started as a marketing differentiation strategy quickly became widespread and common in the industry. Consequently, the economic viability of broiler production without the use of antibiotics has become a subject of ongoing debate and analysis within the poultry industry, with some producers switching back to the practice of using antibiotics (some categories, such as antibiotics not important in human medicine). However, this type of analysis is never easy or straightforward, as a multitude of factors should be taken into consideration. Here, we attempt to discuss two contrasting broiler production systems, conventional versus no antibiotic ever (NAE), as they represent both ends of the spectrum, regarding the use of antibiotics or no use at all being allowed. The discussion is focused primarily on differences in animal health, growth performance, and food safety. Other areas, such as economics and sustainability are outside the scope of this discussion, but will briefly be touched on, as ultimately, both are directly impacted by the main topics of focus

Resting on transport trailer reduces Salmonella at harvest

A potential intervention strategy to reduce the prevalence of Salmonella enterica at harvest was evaluated, which consisted of resting pigs prior to harvest on their transport vehicle, instead of in the abattoir holding pen. Individual fecal samples were collected at the farm and at the abattoir (n= 120 pigs), where half of the pigs were unloaded, and moved to a holding pen, whereas the other half stayed in the transport trailer

Salmonella enterica prevalence and serotype distribution in swine at slaughter

The objective of this cross-sectional study was to analyze data available from multiple studies conducted by our research team estimating the prevalence of S. enterica, and the serotype d1stribution in swine at slaughter, based on different sample types A total of 1,110 pigs from three large capacity abattoirs located in the Midwestern U S. were individually sampled at slaughter. Individually paired samples collected mcluded. cecal contents and ileocecal lymph nodes. Samples were collected on multiple occasions in all three abattoirs, transported to the laboratory, and processed for the isolation and identification of S. enterica. The overall prevalence of S. enterica, based on cecal contents, mesentenc lymph nodes, and any of the samples (i.e., cecal contents and/or mesenteric lymph nodes) was 54.7%, 27.9%, and 62.6%, respectively. There was a Significant difference (P\u3c0.05) between prevalence estimates based on cecal contents and mesenteric lymph node samples in all three abattoirs, and overall. A variety of S. enterica serotypes was isolated m all abattoirs The average number of serotypes isolated per group was 3.48. This study confirms that the S. entenca prevalence at slaughter in swine is high, requiring attention due to the associated risk of contamination of the abattoir environment. Moreover, our results demonstrate the common occurrence of a high diversity of serotypes in swine at slaughter. This study also shows that both cecal contents and mesenteric lymph nodes should be considered for a better estimate of S. enterica prevalence at slaughter

Salmonella prevalence in first pull versus close out market pigs

Identifying potential risk factors to direct intervention strategies is fundamental to reduce the risk of pork contamination with Salmonella. This study was designed to compare the Salmonella prevalence in the first group of pigs selected for slaughter (uFirst pull ) versus the last group of pigs selected for slaughter ( Close out ) from typical commercial finishing barns containing 800 - 1,000 animals. Nine finishing barns from two production sites were included in the study {4 paired samplings from site A, and 5 paired samplings from site B). Each paired sampling consisted in matched groups of pigs from the same barn as the first pair and the close out with a 4-week interval between groups. From each group, individual fecal samples (n = 45) and meat samples (n = 50) were collected, on-farm and at slaughter, respectively. In the laboratory, fecal samples were selectively enriched, and analyzed for the presence of Salmonella by a commercially available antigen-capture ELISA. Meat samples were kept frozen, and thawed for processing. The resulting liquid ( meat juice ) was collected and analyzed for the presence of antibodies against Salmonella by a commercially available ELISA. All lots of pigs housed in the finishing barns studied were Salmonella-positive, based on sampling from first pull and close out . In 7/9 (77.8%) of the studied barns, an increase in Salmonella prevalence was observed, based on both bacteriologic and serologic analysis. Overall, there was an increase of 9.3% (P\u3c0.05) in bacteriologic prevalence, and 25.1% (P\u3c0.05) in serologic prevalence from first pull to close out groups. This study demonstrates that a significant increase of Salmonella prevalence occurs between the first and the last group of pigs from a finishing barn shipped to slaughter. In conclusion, close out groups of finishing pigs constitute a higher risk for Salmonella contamination of pork products

Sampling cecal contents or ileocecal lymph nodes: is it different?

The objective of this study was to compare the prevalence of Salmonella enterica in swine populations estimated by sampling cecal contents versus ileocecal lymph nodes. In each of two abattoirs, four groups of pigs (n=30 pigs per group) were studied. Cecal contents and ileocecal lymph nodes were individually collected and processed for isolation and identification of S. enterica. The overall prevalence found by cecal contents was 40%, whereas by ileocecal lymph nodes it was 22.9% (p\u3c0.05). Combining results from both samples, the prevalence found was 50.8%. The relative sensitivity of cecal content sampling was 79.3%, whereas for ileocecal lymph node sampling it was 45.5%. The agreement (Kappa statistic) between both sample types was 13.1%. This study demonstrates that sampling either cecal contents or ileocecal lymph nodes affects results of S. enterica epidemiological studies. It is recommended that both samples be used

Genetic relatedness of Salmonella enterica isolates from pens and swine at slaughter

The study aimed to determine if Salmonella enterica isolates from the floor of pre-slaughter holding pens were genetically related to isolates found in swine, held in those pens, post slaughter. Pulsed-field gel electrophoresis (PFGE) typing was used to determine genetic relatedness. On seven occasions, 100% homologous PFGE patterns were found, i.e. the pen and pig isolates were identical. This suggested that pen to pig transfer of Salmonella enterica occurred. Isolates from PFGE patterns associated with pig to pen transfers were more likely to occur in the S. Anatum, S. Heidelberg and S. Typhimurium serotypes. The ability of an isolate from a pen to rapidly infect animals housed in the pen may vary within serotype based on factors described by the PFGE pattern. This may explain why some S. enterica serotypes are prevalent in swine but not in pork products or humans

Effect of feed withdrawal and transportation on Salmonella enterica infection in market-weight pigs

A study was conducted to determine if two common pre-slaughter stressors, feed withdrawal and transportation, affect the levels of Salmonella in infected market pigs. A total of 60 market-weight pigs (220- 240 lbs.) were individually inoculated (intranasally; 105 cfu/mL) with Salmonella enterica serovar Typhimurium. The experiment was replicated 3 times with 20 pigs per replicate. Individual fecal samples were collected to confirm establishment of the infection (3 samples per pig) prior to treatment assignment

Experimental Salmonella enterica infection in market-weight pigs

Market pigs infected with Salmonella pose significant food safety risk by carrying the pathogen into abattoirs. A study was conducted to determine the dynamic of Salmonella infection in market-weight pigs (220-240 lbs.). Pigs (n=24) were individually inoculated (intranasally; 108 cfu/mL) with Salmonella enterica serovar Typhimurium. Fecal samples were collected from each pig, and 3 pigs were randomly selected and euthanized to collect additional samples (spleen, liver, mesenteric lymph node, ileal and cecal contents) on days 1, 2, 7, 14, 21, 28, 35, and 42 post-inoculation (p.i.)

Experimental rapid infection in market swine following exposure to a Salmonella contaminated environment

The objective of these experiments was to evaluate the possibility of swine becoming infected with Salmonella typhimurium from an environment contaminated with feces in a short time interval. Two experiments were conducted. In Experiment 1, pigs were necropsied at 2 (n=10) and 6 (n=5) hours after continuous exposure to an environment contaminated with nalidixic acid-resistant Salmonella typhimurium (χ4232)