Microbial and nutritional aspects of feeding fermented feed (poultry by-products) to pigs

Research Progress of Biological Feed in Beef Cattle

Biological feed is a feed product developed through bioengineering technologies such as fermentation engineering, enzyme engineering, protein engineering, and genetic engineering. It possesses functional characteristics of high nutritional value and good palatability that can improve feed utilization, replace antibiotics, enhance the health level of livestock and poultry, improve the quality of livestock products, and promote a better breeding environment. A comprehensive review is provided on the types of biological feed, their mechanism of action, fermenting strains, fermenting raw material resources, and their current status in animal production to facilitate in-depth research and development of applications.

Advances in research on solid-state fermented feed and its utilization: The pioneer of private customization for intestinal microorganisms

With sustainable development of biotechnology, increasing attention has been placed on utilization of solid-state fermented feed (SFF). Solid-state fermented feed has been a candidate strategy to alleviate the contradiction between supply and demand of feed resources, ensure food hygiene safety, promoting energy conservation, and emission reduction. In production of SFF, a variety of organic acids, enzymes, vitamins, peptides, and other unknown growth factors are produced, which could affect performance of animals. Solid-state fermented feed produced by different fermentation techniques has great instability on different physiological stages of different animals, which hinders the application and standardized production of SFF. Herein, we summarize the current advances in the role of the characteristics of SFF prepared by different manufacturing technique and its research progress in animal experiments on growth performance, gastrointestinal ecology, and immune system, so as to provide references for further acquiring a relatively perfect set of SFF production and evaluation systems.

Combination of Antimicrobial Starters for Feed Fermentation: Influence on Piglet Feces Microbiota and Health and Growth Performance, Including Mycotoxin Biotransformation in vivo

The aim of this study was to apply a combination of the microbial starters Lactobacillus uvarum LUHS245, Lactobacillus casei LUHS210, Pediococcus acidilactici LUHS29, and Pediococcus pentosaceus LUHS183 for feed fermentation and to evaluate the influence of fermentation on feed acidity and microbiological characteristics, as well as on the piglet feces microbiota, health, and growth performance. Additionally, mycotoxin biotransformation was analyzed, including masked mycotoxins, in feed and piglet feces samples. The 36-day experiment was conducted using 25-day-old Large White/Norwegian Landrace (LW/NL) piglets with an initial body weight of 6.9–7.0 kg, which were randomly distributed into two groups (in each 100 piglets): control group, fed with basal diet (based on barley, wheat, potato protein, soybean protein concentrate, and whey powder), and treated group, fed with fermented feed at 500 g kg⁻¹ of total feed. Compared to a commercially available lactic acid bacteria (LAB) combination, the novel LAB mixture effectively reduced feed pH (on average pH 3.65), produced a 2-fold higher content of L(+) lactic acid, increased viable LAB count [on average 8.8 log₁₀ colony-forming units (CFU) g⁻¹], and led to stable feed fermentation during the entire test period (36 days). Fecal microbiota analysis showed an increased number of probiotic bacteria in the treated group, particularly Lactobacillus, when compared with the control group at the end of experiment. This finding indicates that fermented feed can modify microbial profile change in the gut of pigs. In treated piglets' blood (at day 61), the serum high-density lipoprotein (HDL) cholesterol and triglycerides (TG) were significantly higher, but the levels of T4, glucose, K, alkaline phosphatase (AP), and urea were significantly decreased (p ≤ 0.05) compared with the control group. Mycotoxin analysis showed that alternariol monomethyl ether (AME) and altenuene were found in 61-day-old control piglets' feces and in fermented feed samples. However, AME was not found in treated piglets' feces. Feed fermentation with the novel LAB combination is a promising means to modulate piglets' microbiota, which is essential to improve nutrient absorption, growth performance, and health parameters. The new LAB composition suggests a novel dietary strategy to positively manipulate fermented feed chemicals and bio-safety and the piglet gut microbial ecology to reduce antimicrobials use in pig production and increase local feed stock uses and economical effectiveness of the process.

Bacillus subtilis and Enterococcus faecium co-fermented feed regulates lactating sow's performance, immune status and gut microbiota

Fermented feed (FF) is widely applied to improve swine performance. However, the understandings of the effects of FF on the immune status and gut microbiota of lactating sows and whether probiotics are the effective composition of FF are still limited. The present study aimed to investigate the performance, immune status and gut microbiota of lactating sows fed with a basal diet supplemented with Bacillus subtilis and Enterococcus faecium co-fermented feed (FF), with the probiotic combination (PRO) of B. subtilis and E. faecium and control diet (CON) as controls. Compared with the CON group, FF group remarkably improved the average daily feed intake of sows and the weight gain of piglets, while significantly decreased the backfat loss, constipation rate of sows and diarrhoea incidence of piglets. The yield and quality of milk of sows in FF group were improved. Besides, faecal acetate and butyrate were promoted in FF group. Additionally, FF increased the level of IgG, IgM and IL-10 and decreased the concentration of TNF-α in serum. Furthermore, FF reduced the abundance of Enterobacteriaceae and increased the level of Lactobacillus and Succiniclasticum, which were remarkably associated with growth performance and serum immune parameters. Accordingly, microbial metabolic functions including DNA repair and recombination proteins, glycolysis and gluconeogenesis, mismatch repair and d-alanine metabolism were significantly upregulated, while amino acid metabolism was downregulated in FF group. Overall, the beneficial effects of FF were superior to PRO treatment. Altogether, administration of FF during lactation improved the performance and immune status, and modulated gut microbiota of sows. Probiotics are not the only one effective compound of FF.

Health-promoting effects of Lactobacillus-fermented barley in weaned pigs challenged with Escherichia coli K88. Animal 2019;14:39-49. [PMID: 31426877 DOI: 10.1017/s1751731119001939]

Fermented feeds are being considered as practical alternatives to antimicrobial growth promoters (AGP) supplemented in nursery pig diets. This study aimed to investigate health-promoting effects of fermented barley in weaned pigs challenged with Escherichia coli K88 +. A total of 37 piglets were weaned at 21 ± 1 day of age (6.41 ± 0.47 kg of BW) and assigned to either of the following five treatment groups: (1) unchallenged control (UCC; n = 7), (2) challenged control (CC; n = 7), (3) AGP (CC + 0.1% AGP; n = 7), (4) Ferm1 (challenged and fed homofermentative Lactobacillus plantarum (Homo)-fermented barley; n = 8) and (5) Ferm2 (challenged and fed heterofermentative L. buchneri (Hetero)-fermented barley; n = 8). The control diet included unfermented barley. Barley was fermented with either Homo or Hetero for 90 days under anaerobic conditions. On day 10, all pigs except those in UCC group were orally inoculated with E. coli K88 + (6 × 109 colony forming units/ml). The pre-planned orthogonal test was performed to compare (1) UCC and CC, (2) CC and AGP, (3) CC and Ferm1 + Ferm2, as well as (4) Ferm1 and Ferm2. Challenged control pigs showed shorter (P < 0.05) villus height (VH) in the duodenum and deeper (P < 0.05) crypt depth (CD) in the jejunum than UCC pigs. The AGP group had higher (P < 0.05) VH and lower (P < 0.05) IL-6 gene expression in the jejunum compared with CC group. Compared to CC, Ferm1 and Ferm2 had decreased (P < 0.05) CD in the duodenum, IL-6 gene expression in the jejunum and rectal temperature at 24 h post-challenge. Pigs fed fermented barley diets showed greater (P < 0.05) faecal abundance of Clostridium Cluster IV and Lactobacilli than those fed UCC diet. Ferm2-fed pigs showed lower (P < 0.05) concentrations of band cells, eosinophils and lymphocytes at 6, 24 and 48 h after challenge, respectively, and lower (P < 0.05) faecal abundance of Enterobacteriaceae 24 h after challenge than the Ferm1-fed pigs. In conclusion, the substitution of unfermented barley with fermented barley in a nursery diet showed similar results as those shown by AGP supplementation in terms of enhancing the intestinal morphology and modulating faecal microbiota composition, as well as down-regulating the pro-inflammatory cytokines; therefore, fermented barley can be a possible nutritional strategy for managing nursery pigs fed diets without in-feed AGP.

Microbiota in fermented feed and swine gut

Development of alternatives to antibiotic growth promoters (AGP) used in swine production requires a better understanding of their impacts on the gut microbiota. Supplementing fermented feed (FF) in swine diets as a novel nutritional strategy to reduce the use of AGP and feed price, can positively affect the porcine gut microbiota, thereby improving pig productivities. Previous studies have noted the potential effects of FF on the shift in benefit of the swine microbiota in different regions of the gastrointestinal tract (GIT). The positive influences of FF on swine gut microbiota may be due to the beneficial effects of both pre- and probiotics. Necessarily, some methods should be adopted to properly ferment and evaluate the feed and avoid undesired problems. In this mini-review, we mainly discuss the microbiota in both fermented feed and swine gut and how FF influences swine gut microbiota.

Effects of supplementing sow diets with fermented corn and soybean meal mixed feed during lactation on the performance of sows and progeny

In the present study, two experiments were performed to study the effects of feeding fermented corn and soybean meal mixed feed (FMF) with Bacillus subtilis and Enterococcus faecium to lactating sows on the performance of the sows and their progeny. In experiment 1, 60 sows were allocated to the following three dietary treatments: 1) sows fed a corn and soybean meal basal diet (control) from day 3 before parturition to weaning, 2) sows fed a diet with 7.5% FMF, and 3) sows fed a diet with 15% FMF. Results indicated that feeding 15% FMF significantly improved (P < 0.05) the sows' ADFI, the individual piglet weaning weights, and piglet weight gain and reduced (P < 0.05) the backfat loss of sows compared with the control group. However, the 7.5% FMF treatment did not alter the performance of the sows or their progeny. Therefore, we considered the level of 15% FMF to be more efficient than 7.5% FMF. To verify the results of experiment 1, we performed experiment 2, in which 60 sows at 111 d of gestation were allocated into the following two dietary treatments: 1) sows fed a basal lactation diet (control) from d 111 of gestation to weaning and 2) sows fed a basal diet with 15% FMF. Compared with the control group, 15% FMF inclusion significantly increased (P < 0.05) the sows' ADFI, litter weight gain, and individual piglet weight gain during lactation and markedly decreased the backfat loss of sows (P < 0.05) and piglet diarrhea incidence (P < 0.05). Additionally, the milk yield and IgA contents of the milk in sows fed 15% FMF were greater (P < 0.05) than those of the control group. Furthermore, the apparent total tract digestibility of GE, DM, and total P of sows was increased (P < 0.05) with 15% FMF supplementation. Therefore, the present study indicates that supplementing sow diets with 15% FMF from parturition to weaning has the potential to 1) increase sow ADFI, milk production, milk IgA content, and nutrient digestibility and promote sow reproductive performance by shortening the weaning-to-estrous interval and 2) promote the growth performance of their progeny and decrease diarrhea incidence.

Effect of feeding fermented liquid feed and fermented grain on gastrointestinal ecology and growth performance in piglets

To investigate the microbial and nutritional characteristics of dry feed, liquid feed containing fermented liquid cereal grains, and fermented liquid feed, and their effect on gastrointestinal ecology and growth performance, 120 piglets from 40 litters were used and housed in pens with 5 animals in each. The 3 dietary treatments (all nonheated and nonpelleted diets) were: a dry meal diet (DRY); a fermented, liquid cereal grain feed (FLG); and a fermented liquid feed (FLF). The FLG diet was prepared by storing the dietary cereals (barley and wheat) and water (1:2.5, wt/wt) in a closed tank at 20 degrees C and adding the remaining dietary ingredients immediately before feeding. The FLF diet was prepared by storing compound feed and water (1:2.5, wt/wt) in a closed tank at 20 degrees C. Three times daily, 50% of the fermented cereals or compound feed and water stored in the tanks was removed and replaced with an equal amount of fresh cereals or feed and water. On d 14, 1 piglet from each pen was killed and samples from the gastrointestinal tract were obtained. The pH of the fermented cereals was 3.85 (SD = 0.10), that of the FLG diet was 5.00 (SD = 0.18), and the pH of the FLF diet was 4.45 (SD = 0.11). The dietary concentration of lysine (g/16 g of N) pointed to a decreased concentration in the FLF (5.46, SD = 0.08) compared with the DRY (6.01) and FLG (6.21, SD = 0.27) diets, and the concentration of cadaverine was greater in the FLF diet (890 mg/kg, SD = 151.3) than in the DRY (32 mg/kg) or FLG (153 mg/kg, SD = 18.7) diets. Fermenting only the cereal component of the diet (FLG) promoted the growth of yeasts to a greater extent than fermenting the whole diet (FLF). Terminal RFLP profiles of diets and digesta from the stomach and midcolon showed differences among dietary groups. The number of yeasts able to grow at 37 degrees C in the stomach and caudal small intestine was greatest in the FLG group compared with the other 2 dietary groups (P < 0.01). In the cecum and colon, the differences were only significant between piglets fed the FLG and the FLF diets (P < 0.05). The greatest number of yeasts able to grow at 20 degrees C was detected in the animals fed the FLG diet. However, the values were different from the FLF-fed piglets only in the stomach (P < 0.05) and midcolon (P < 0.05). There was a tendency (P < 0.10) for greater ADG of the piglets fed the FLG compared with the FLF diet. Feeding liquid feed containing fermented, liquid cereal grains as a means of avoiding microbial decarboxylation of free amino acids in the feed and increasing feed intake by improving palatability seems promising but requires further investigation.

Performance, feeding behaviour and microbial diversity in weaned piglets fed liquid diets based on water or wet wheat-distillers grain

Performance, nutrient digestibility, feeding behaviour, diarrhoea frequency and faecal microbial diversity was studied in weaned piglets allotted to dry feed (diet A), liquid feed with water (diet B) or liquid feed with wet wheat-distillers grain (diet C). There were no differences in digestibility of organic matter and energy, and the performance was similar between piglets fed liquid diets. Piglets fed diet A spent more time on eating/drinking compared with piglets fed liquid diets. The frequency of diarrhoea decreased (p < 0.05) from from diet A (11 out of 16) to diet B (6 out of 16) and further to diet C (1 out 16). The type of diet did not affect the diversity of coliform bacteria or lactobacilli, but the composition of the Lactobacillus flora was changed. The lower diarrhoea frequency when feeding diet C may be due to a prophylactic effect induced by the inclusion of wet wheat-distillers grain in the diet.

Probiotics and prebiotics: role in clinical disease states

Parents of pediatric patients are seeking alternatives to conventional therapy in the prevention and treatment of gastrointestinal disease states because of therapeutic failures caused by the increased incidence of antibiotic resistance. One such alternative is the use of probiotics and prebiotics to stimulate health-promoting indigenous flora to affect pathogen colonization and expression of disease. Probiotics are live flora given in oral quantities that allow for colonization of the colon. Probiotics are given as functional foods or dietary supplements, and function to activate the mucosal immune system and prevent pathogen colonization and translocation by strengthening the mucosal barrier, interfering with pathogen colonization, and in some instances, producing secretory antibacterial substances. Prebiotics are nondigestible carbohydrates, principally oligosoccharides, that are fermented by colonic commensals, stimulating their proliferation and producing short-chain fatty acids. Both protective nutrients have been shown to reduce the incidence and severity of infantile diarrhea, particularly rotaviral gastroenteritis, prevent antibiotic-induced diarrhea, and prevent and treat intestinal food allergy. With additional multicenter clinical trial confirmations, these substances may become routine in the care of infants and young children.

Fermented and nonfermented liquid feed to growing pigs: effect on aspects of gastrointestinal ecology and growth performance

The effect of feeding dry feed (DF), nonfermented liquid feed (NFLF), and fermented liquid feed (FLF) to growing pigs on aspects of gastrointestinal ecology and on performance was investigated. Nonfermented liquid feed was prepared by mixing feed and water at a ratio of 1:2.5 immediately before feeding. Fermented liquid feed was prepared by mixing feed and water in the same ratio as NFLF, and stored in a tank at 20 degrees C for 4 d, after which half the volume was removed twice daily at each feeding and replaced with the same volume of feed and water mixture. A total of 60 pigs (initial BW of 30.7 kg) from 20 litters was used. Twenty pigs, housed individually, were allotted to each of the diets and fed restrictively. Five pigs from each diet were sacrificed at an average BW of 112 kg and digesta from the gastrointestinal tract (GI-tract) was obtained to examine variables describing some aspects of the gastrointestinal ecology. Fermented liquid feed contained high levels of lactic acid bacteria (9.4 log cfu/g) and lactic acid (approximately 169 mmol/kg), low levels of enterobacteria (<3.2 log cfu/g), and had a low pH (4.4). Nonfermented liquid feed contained 7.2 log cfu/g of lactic acid bacteria, and 6.2 log cfu/g of enterobacteria, which indicated that fermentation had started in the feed. The pigs fed FLF had the lowest levels of enterobacteria along the GI-tract (<3.2 to 5.0 log cfu/g), and those fed NFLF the highest levels (5.7 to 6.6 log cfu/g; P < or = 0.02). Fermented liquid feed caused a decrease in gastric pH from 4.4 and 4.6 for DF and NLF, to 4.0 (P = 0.003), and increased numerically the gastric concentration of lactic acid (P = 0.17) from 50 to 60 mmol/kg in the DF and NFLF treatments to 113 mmol/kg in the FLF treatment. The animals fed NFLF showed the highest weight gain (995 g/d) and feed intake (2.14 kg/d), and those fed FLF the lowest values (weight gain, 931 g/d; feed intake, 1.96 kg/d; P = 0.003 for weight gain, and P < 0.001 for feed intake). The results from the present study indicate that feeding FLF as prepared here may be a valid feeding strategy to decrease the levels of enterobacteria in the GI-tract of growing pigs, whereas feeding liquid feed that has started to ferment (high levels of enterobacteria and high pH as with NFLF) increases the presence of these undesirable bacteria. Nonetheless, higher daily feed intake and body weight gain are obtained when feeding NFLF compared with feeding FLF or DF.

Effect of fermented feed on shedding of Enterobacteriaceae by fattening pigs

Epidemiological studies showed that the use of fermented feed could significantly reduce Salmonella prevalence in pigs compared to the use of normal feed. Experimental challenge experiments with Salmonella have however never been conducted to reveal the efficacy of fermented feed in reducing Salmonella shedding and/or reducing the number of Salmonella-positive pigs. A longitudinal study was conducted to measure the effect of fermented feed, in particular of its components lactic acid and Lactobacillus plantarum, on gastrointestinal bacterial ecology (Salmonella, Enterobacteriaceae, lactobacilli, volatile fatty acids (VFAs), pH). Seeder pigs were used as a mode for Salmonella transmission within a pig herd. Bacteriological measurements were performed in faeces of the pigs. The results showed that fermented feed affected/reduced the Enterobacteriaceae population in faeces of the pigs. No differences were found in the number of positive pigs infected or in the number of shedding with Salmonella serovar Typhimurium fed fermented feed and between the normal feed group. S. serovar Goldcoast could not establish an infection in the seeder pigs in the fermented feed group as well as in the normal feed group. The pH of the faeces in the fermented feed groups was significantly higher than the pH of the faeces of the normal feed groups. The role of the undissociated form of the faecal VFAs on the significantly lower Enterobacteriaceae number in faeces of the pigs of the fermented feed groups could not be demonstrated because of the significant higher pH in the faeces of the pigs fed fermented feed.

A longitudinal study of Salmonella enterica infections in high-and low-seroprevalence finishing swine herds in The Netherlands

The purpose of this investigation was to study the incidence and course of Salmonella infections in finishing pig herds in order to asses the stability of a given Salmonella herd status. Five low- and 7 high-seroprevalence herds were followed for seven sampling rounds. Each round, blood and faecal samples were tested in an indirect ELISA and by bacteriological culturing, respectively. In high-seroprevalence herds a positive Salmonella status was an indication of a long-term problem and the status was relatively stable over time. The herds experiencing clinical salmonellosis were not necessarily the herds with the highest seroprevalence. It is possible to deliver sero-negative finishers to the slaughterhouse, even though these pigs were seropositive as growers. In three out of five low-prevalence herds, major infection incidents occurred, indicating that changes in the Salmonella status should be anticipated. Low-prevalence herds can remain negative over a longer period of time as a result feeding a complete liquid feed containing fermented by-products.

Administration of acidified drinking water to finishing pigs in order to prevent Salmonella infections

The aim of the study was to test whether acidified drinking water, with two millilitres of an acid mixture per litre, was able to reduce the number of Salmonella infections in finishing pig herds. In each compartment, half of the pens were supplied with acidified water and the other pens served as negative control. In three herds the required dose was not applied to the pigs as a result of various practical problems. In another herd, all pigs remained seronegative throughout the study. Analysis of the remaining three herds showed a large and significant treatment effect in one herd (P<0.001). As a result of the small number of observations and the overall lower seroprevalence in the control groups, the other two herds only showed a statistical trend to a treatment effect (0.10<P<0.05). The main practical problem was the clogging of drinking nipples as a result of fungal growth in the pipelines.

Effect of fermented feed on the microbial population of the gastrointestinal tracts of pigs

An in vivo experiment was performed with pigs to study the inhibitory effect of fermented feed on the bacterial population of the gastrointestinal tract. Results demonstrated a significant positive correlation between pH and lactobacilli in the stomach contents of pigs in dry feed as well as in the stomach contents of pigs fed fermented feed. Furthermore, a significant positive correlation between the pH and the numbers of bacteria in the family Enterobacteriaceae in the contents of the stomach of pigs fed dry feed was found. In the stomach contents of pigs fed fermented feed, a significant negative correlation was found between the concentration of the undissociated form of lactic acid and the numbers of Enterobacteriaceae. The numbers of Enterobacteriaceae in the contents of the stomach, ileum, cecum, colon, and rectum of pigs fed fermented feed were significantly lower compared with the contents of the stomach, ileum, caecum, colon, and rectum of pigs fed dry feed. The numbers of total lactobacilli were significantly higher in the stomach contents of pigs fed fermented feed and in the ileum contents of one pig group fed fermented feed compared with the contents of pigs fed dry feed. However, the influence of lactobacilli on numbers of Enterobacteriaceae could not be demonstrated. It was concluded that fermented feed influences the bacterial ecology of the gastrointestinal tract and reduces the levels of Enterobacteriaceae in the different parts of the gastrointestinal tract.

Herd level husbandry factors associated with the serological Salmonella prevalence in finishing pig herds in The Netherlands

A national program to reduce Salmonella in pork and pork products should include monitoring and intervention at farm level. To develop an adequate intervention strategy at farm level, risk factors for Salmonella infections in finishing pigs have to be determined. In this study, blood samples were collected randomly at two slaughterhouses from slaughter pigs. Samples were tested by the Dutch Salmonella ELISA, based on the O-antigens 1, 4, 5, 6, 7 and 12, using a cut-off of OD%=10. This ELISA has been calibrated against the Danish ELISA to give comparable results. Workers from herds from which at least forty blood samples had been collected, were asked to participate in a questionnaire. In total, 353 questionnaires were obtained and analysed. Significant risk factors associated with the proportion of seropositive samples were identified by multiple linear logistic regression. The feeding of a complete liquid feed containing fermented by-products and the omission of disinfection after pressure washing a compartment as part of an all-in/all-out procedure, were both associated with a lower Salmonella seroprevalence. A small to moderate herd size (<800 finishing pigs), a previous diagnosis of clinical Salmonella infection in the herd, the use of tylosin as an antimicrobial growth promoter in finishing feed, or herds which had more than 16% of the livers of their pigs condemned at the slaughterhouse as a result of white spots were associated with a higher Salmonella seroprevalence. Hypothetical intervention strategies based on these risk factors can be studied for their effect on the Salmonella seroprevalence and practical applicability in field studies.

Identification and quantification of risk factors in animal management and transport regarding Salmonella spp. in pigs

This article discusses the main elements of a descriptive epidemiological model for Salmonella spp. in the pre-harvest stages of pork production, and the subsequent quantification of risk factors. About two thirds of all Dutch pig farms are more or less permanently infected. At infected finishing farms, the current probability that Salmonella-free pigs will become infected is about 85%. In the case that a certain pen is infected, the current probability that further pen-to-pen transmission will occur is about 90% and that (human) vectors will also spread the infection 60%. Between 5-30% of the animals may still excrete Salmonella spp. at the end of the finishing period, and this percentage can double during transport and lairage. In infected pigs at slaughter weight, the Salmonella spp. are foremost located in the digestive tract, its contents and the closely associated lymph nodes. Under the current circumstances, the lack of farm hygiene (odds ratio (OR) 39.7), (re)contaminated feed (OR 1.6), the use of broad spectrum antibiotics (OR 5.6), a positive Salmonella-status of animals before transport (roughly estimated OR 4.0), the lack of transport hygiene (roughly estimated OR 1.1) and transport stress (OR 1.9) are the most important risk factors regarding infections with Salmonella spp. Currently the role of on-farm contamination cycles with endemic ('house flora') Salmonella spp. is so important, that the role of other factors is difficult to ascertain. It is also concluded that the farm-phase forms the core of all current problems, and that better prevention and control can be achieved by, (i) very strict and consistent farm hygiene in combination with promotion of the colonization resistance of animals kept together with a prudent use of broad spectrum antibiotics; (ii) simultaneous execution of control programmes at breeding farms, multiplying farms and finishing farms; (iii) separate transport, lairage and slaughter of the animals thus produced.

Utilization of fermented flocculated poultry sludge as a feed constituent for pigs

Flocculated poultry sludge was mixed with 3% molasses and was flow-therm pasteurized for 5 min at a core temperature of 95 C. The sludge was subsequently cooled to between 20 and 25 C and fermented with Lactobacillus plantarum as starter culture. Three groups of eight 8- to 10-wk-old, individually housed fattening pigs (Hypor) were fed according to a fixed scheme correlated with age. One control group received a restricted ration of commercial compound feed (Group A). The other control group was provided "nearly ad libitum" access to the same commercial compound feed (Group C). The experimental group received the same amount of commercial compound feed as Group A, but the diet was supplemented with fermented sludge, at an inclusion rate of 19 to 28% of the total ration (DM basis). The pigs fed the sludge-containing diet and those receiving the compound pig feed "nearly ad libitum" showed comparable growth results. It was concluded that the net energy (NEpig) level of .68 g DM of sludge was comparable to the NEpig level of 1 g compound pig feed (88% DM). A decrease in colony counts of Enterobacteriaceae in the intestinal tract of the pigs, was regarded as positive, as it might lower the risk of disturbance of the gut flora by enteropathogenic bacteria such as Escherichia coli and Salmonella. No adverse effects on health and performance were observed as a result of the feeding of pasteurized and subsequently fermented flocculated poultry sludge to fattening pigs. It is concluded that this sludge can serve as a valuable feed constituent as long as it is processed properly.