The objective of this study was to determine the effect of the acidification of pelleted feed on the carriage and seropositivity against Salmonella in finisher pigs of a commercial herd. Three different diets were assayed: 0.8% formic acid (group 1); 0.4% lactic acid plus 0.4% formic acid (group 2) and a feedstuff without additives (group 3). one thousand pigs were included in each treatment that was administered from 19 to 26 weeks of age

Creus, Eva

Mateu, Enric

Pérez, J. Francisco

English

The objective of this study was to determine the effect of the acidification of pelleted feed on the carriage and seropositivity against Salmonella in finisher pigs of a commercial herd. Three different diets were assayed: 0.8% formic acid (group 1); 0.4% lactic acid plus 0.4% formic acid (group 2) and a feedstuff without additives (group 3). one thousand pigs were included in each treatment that was administered from 19 to 26 weeks of age.</p

Digital Repository @ Iowa State University (ISU)

POSTERPRESENTATIONS287SafePork 2005EFFECT OF AN ACIDIFIED DIET ON SALMONELLAPREVALENCE DURING THE LAST TERM OF FATTENINGPERIODEva Creus1*, J. Francisco Pérez1, Enric Mateu2,3*1Dept. Ciència Animal i dels Aliments, Facultat de Veterinària, Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra,Spain, Ph: +34935811556, E-mail: eva.creus@uab.es; 2Dept. de Sanitat i Anatomia Animals, Facultat de Veterinària, UAB,Bellaterra, Spain; 3Centre de Recerca en Sanitat Animal (CreSA), UAB, Bellaterra, SpainAbstract The objective of this study was to determine the effect of the acidification of pelletedfeed on the carriage and seropositivity against Salmonella in finisher pigs of a commercial herd. Three different diets were assayed: 0.8% formic acid (group 1); 0.4% lactic acid plus 0.4%formic acid (group 2) and a feedstuff without additives (group 3). One thousand pigs were includ-ed in each treatment that was administered from 19 to 26 weeks of age. Blood, faecal contentand mesenteric lymph nodes were collected at slaughter (30 pigs/group). The diet including lacticand formic acids significantly reduced Salmonella seroprevalence compared to the diet withoutadditives (p<0.05) but there were no differences on the faecal excretion or in Salmonella carriagein mesenteric lymph nodes. Our results suggest that the administration of a combination of lacticand formic acids at the levels used in this study can be helpful to reduce Salmonella prevalence infinishing pigs. Introduction Feeding strategies have shown to be effective for reducing the incidence ofSalmonella in pigs when combined with other measures such as hygiene and adequate manage-ment practices. Several studies reported that meal feed had a protective effect against subclinicalSalmonella infection in pigs. However, these diets have a negative effect on the productivity(Kjeldsen and Dahl, 1999; Wondra et al., 1995). Meal feed allows optimal conditions for the pro-duction of organic acids in the gastrointestinal tract of pigs. These acids are known to inhibitSalmonella (van Winsen et al., 2001). High levels of organic acids in the gut can be also achievedthrough the acidification of feed. The aim of this study was to examine the effect of using pelletedfeed added with organic acids for the last weeks prior to slaughter, on the prevalence ofSalmonella in age-market pigs of a commercial herd.Materials and Methods The study was carried out in a commercial herd subclinically infectedwith Salmonella. Before starting the administration of the experimental diets, serological analysisindicated that, at 17 weeks of age, at least 20% of pigs were seropositive. From previous studiesa 40% seroprevalence was expected when pigs were 26 weeks old.Three groups were included in the trial. Group 1 received a commercial pelleted feed addedwith 0.8% formic acid; group 2 received the commercial feed added with 0.4% lactic acid plus0.4% formic acid and group 3 received the commercial feed without additives. Each group had1,000 finishing pigs. Diets were administered for the last seven weeks before the slaughter ofthe pigs (from 19 to 26 weeks of age). The effect of the three diets on Salmonella prevalence wasmeasured by analyzing samples from 30 pigs/ group (blood, faecal contents and mesentericlymph nodes). Samples were taken at the slaughterhouse and carcass weights were also record-ed. With this sampling we expected to be able to determine a reduction of prevalence from 40%in untreated pigs to 20% in treated pigs (95% confidence level, 80% power). Serum samples were tested by an indirect mix-ELISA based on the O-antigens 1, 4, 5, 6, 7and 12, using a cut-off of 40% of the positive control. Bacteriological analysis were done bymeans of an initial enrichment of samples in buffered peptone water, transfer to Rappaport-Vassiliadis broth (42°C, 48 h) and final plating onto XLT4 medium. Final identification was done bymeans of the API20E test and serotyping.  Results At the end of the study the highest seroprevalence was observed in group 3 (28/30,93.3%) followed by group 1(26/30, 88.6%) and group 2 (20/30, 66.6%). These differences werestatistically significant (p=0.02). Tukey test for multiple comparisons showed that seroprevalencein group 2 was different from that of the controls (p=0.019) and showed a trend to be differentfrom group 1 (p=0.05). In contrast, no differences were seen in the faecal or lymph node carriage(Table 1). Two Salmonella serovars were isolated from faeces: Typhimurium and its monophasic POSTERPRESENTATIONS288 SafePork 2005variant 4,12:i:- and Muenchen, whereas from ileocecal lymph nodes only the Typhimuriummonophasic variant was isolated. Interestingly, only one of the animals with lymph node carriagewas also positive in faeces. No differences in productive records were observed.                         Discussion Several studies have shown the importance of the finishing period for the diffusion ofSalmonella infections in swine herds, particularly when those infections happen shortly before theslaughter. This fact suggests that prevention in that critical period can be helpful to reduce theproportion of carrier pigs reaching the slaughterhouse. Our results showed that acidification offeed was efficient to reduce Salmonella seroprevalence, indicating thus that treatment of group 2(lactic plus formic acids) was helpful to reduce, or at least to slow, the spread of the infection.However, the proportion of Salmonella carriers was similar in all groups. This discrepancy ofresults needs explanation. One possible interpretation is that pigs that had become infectedbefore the administration of the acidified feed and developed a carrier state were not affected bythe treatment. In favor of this hypothesis it can be stated that lymph node carriage was low (1-2pigs/group). In addition, some of these infections could have taken place during the transport andwaiting in the slaughterhouse. Hurd et al., (2001) showed that after a brief exposure to aSalmonella-contaminated environment, pigs can be infected and Salmonella can be recoveredfrom faeces. As shown in our results, of the total 14 culture positive faeces, only one correspond-ed to lymph node carriers. This picture would agree with a recent infection, maybe during trans-port and waiting at the slaughterhouse.Conclusions Our results show that adding a combination of 0.4% lactic acid plus 0.4% formicacid to a commercial pelleted feed during the last term of fattening period can be helpful toreduce Salmonella prevalence in finishing pigs. Although the protective effect of acidified feed,this feeding strategy should be applied in combination with other general measures in farm theentire fattening period.Acknowledgements Our grateful thanks to Grup Baucells for its support for this study.ReferencesHurd, H.S., Gailey, J.K., McKean, J.D., Rostagno, M.H., 2001. Rapid infection in market-weight swine following exposure to aSalmonella Typhimurium-contaminated environment. Am J Vet Res 62:1194-1197Kjeldsen, N. and The effect of feeding non-heat treated, non-pelleted feed compared to feeding pelleted, heat-treated feed onthe salmonella-prevalence of finishing pigs. Proceedings Salinpork, 5-7 August, Washington, USA, p.313-316Van Winsen, R.L., Lipman, L.J., Biesterveld, S., Urlings, B., Snijders, J., and Vanknapen, F., 2001. Mechanism of Salmonellareduction in fermented pig feed. J Sc Food Agric 81:342-346Wondra, K.J., Hancock, J.D., Behnke, K.C., Hines, R.H., Stark, C.R., 1995. Effects of particle size and pelleting on growth per-formance, nutrient digestibility, and stomach morphology in finishing pigs. J Anim Sci 73: 757-63Parameters0.8% formicacid diet0.4% lactic acid +0.4% formic acid dietNon acidifieddietBlood samples 26 (86.6) 20 (66.6) 28 (93.3)Faeces 5 (16.6) 5 (16.6) 4 (13.3)Mesentericlymph nodes1 (3.3) 2 (6.6) 2 (6.6)Table 1. Effect of the examineddiets on Salmonella prevalence.Number of positive samples (%)

Effect of an acidified diet on Salmonella prevalence during the last term of fattening period

Abstract The objective of this study was to determine the effect of the acidification of pelleted feed on the carriage and seropositivity against Salmonella in finisher pigs of a commercial herd. Three different diets were assayed: 0.8 % formic acid (group 1); 0.4 % lactic acid plus 0.4% formic acid (group 2) and a feedstuff without additives (group 3). One thousand pigs were includ-ed in each treatment that was administered from 19 to 26 weeks of age. Blood, faecal content and mesenteric lymph nodes were collected at slaughter (30 pigs/group). The diet including lactic and formic acids significantly reduced Salmonella seroprevalence compared to the diet without additives (p&lt;0.05) but there were no differences on the faecal excretion or in Salmonella carriage in mesenteric lymph nodes. Our results suggest that the administration of a combination of lactic and formic acids at the levels used in this study can be helpful to reduce Salmonella prevalence in finishing pigs. Introduction Feeding strategies have shown to be effective for reducing the incidence of Salmonella in pigs when combined with other measures such as hygiene and adequate manage-ment practices. Several studies reported that meal feed had a protective effect against subclinical Salmonella infection in pigs. However, these diets have a negative effect on the productivit

Eva Creus

J. Francisco Pérez

Enric Mateu

CiteSeerX

http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article%3D1603%26context%3Dsafepork

Effect of an acidified diet on Salmonella prevalence during the last term of fattening period

Abstract

Similar works

Full text

Available Versions

Digital Repository @ Iowa State University (ISU)

CiteSeerX