Joris Missotten

Effects of dose and formulation of carvacrol and thymol on bacteria and some functional traits of the gut in piglets after weaning

Two trials were conducted to study the effects of dose and formulation of carvacrol and thymol on bacterial counts, metabolites and functional traits of the gut in weaned piglets. In the first experiment (Exp. I), 25 piglets (28 d, 6.59 ± 0.48 kg BW) were allocated to five dietary treatments: a control diet, or the same diet supplemented with either carvacrol or thymol at doses of 500 and 2000 mg kg−1. In the second experiment (Exp. II), 35 piglets (28 d, 7.99 ± 0.73 kg BW) were assigned to seven dietary treatments: the same control diet as in Exp. I, or this diet supplemented with thymol in one of three formulations (on celite, on alphacel or microencapsulated) at doses of 500 and 2000 mg kg−1. At 11/12 days post-weaning piglets were euthanised, and digesta from stomach, proximal and distal small intestine were sampled for bacteriological and biochemical analysis. Small intestinal tissue was sampled for histo-morphological determinations. In none of the experiments or sections of the gut was the number of bacteria lowered by the carvacrol or thymol supplementation. In Exp. I, the villus/crypt ratio at the distal small intestine for the experimental diets (1.30–1.32) was higher than for the control diet (1.24) (p < 0.05). Thymol fed animals in Exp. II had a lower number of intra-epithelial lymphocytes at the proximal (p < 0.05) and at the distal (p < 0.1) small intestine as compared to control animals. Mean concentration of the active ingredient in the stomach and proximal small intestine for the 2000 mg kg−1 carvacrol diet was 521 and 5 mg kg−1 fresh digesta, respectively, and for the 2000 mg kg−1 thymol diets it ranged between 475 and 647 and between 13 and 24 mg kg−1 fresh digesta, respectively. Cumulative absorption in the proximal small intestine was higher than 90% for all treatments and was not affected by formulation type. These data suggest that carvacrol and thymol can improve gut health, but evidence for clear antimicrobial effects towards the major culturable bacteria of the pig foregut is limited.

Fermented liquid feed for pigs

Since the announcement of the ban on the use of antibiotics as antimicrobial growth promoters in the feed of pigs in 2006 the investigation towards alternative feed additives has augmented considerably. Although fermented liquid feed is not an additive, but a feeding strategy, the experimental work examining its possible advantages also saw a rise. The use of fermented liquid feed (FLF) has two main advantages, namely that the simultaneous provision of feed and water may result in an alleviation of the transition from the sow milk to solid feed and may also reduce the time spent to find both sources of nutrients, and secondly, that offering FLF with a low pH may strengthen the potential of the stomach as a first line of defence against possible pathogenic infections. Because of these two advantages, FLF is often stated as an ideal feed for weaned piglets. The results obtained so far are rather variable, but in general they show a better body weight gain and worse feed/gain ratio for the piglets. However, for growing-finishing pigs on average a better feed/gain ratio is found compared to pigs fed dry feed. This better performance is mostly associated with less harmful microbiota and better gut morphology. This review provides an overview of the current knowledge of FLF for pigs, dealing with the FLF itself as well as its effect on the gastrointestinal tract and animal performance.

Intact brown seaweed (Ascophyllum nodosum) in diets of weaned piglets: effects on performance, gut bacteria and morphology and plasma oxidative status

The aim was to assess the effects of intact dried Ascophyllum nodosum seaweed on piglet performances, gut bacteria and function and plasma oxidative status. A total of 160 weaned piglets (21 days, 6.59 ± 0.91 kg) were allocated to four dietary treatments with eight pen replicates of five animals each for 28 days: a control diet; based on cereals, soybean meal and milk products, and three basal diets supplemented with either 2.5, 5.0 or 10.0 g dried seaweed per kg. At day 12/13 one piglet from each pen was sacrificed. Plasma samples were taken to determine parameters of oxidative status. Digesta were sampled for microbiological plate countings onto selective media and molecular analysis using PCR-DGGE. Small intestinal tissue was taken for morphological and electro-physiological determinations. Data were analysed by a linear model with treatment as fixed effect. A. nodosum supplementation had no effect on daily weight gain, nor did it alter feed conversion ratio. Plate countings failed to reveal differences among treatments. Dendograms prepared using PCR-DGGE banding patterns did not indicate clustering of microbial profiles based on diet supplement. Plasma oxidative status and outcome of morphology and of electro-physiological measurements from gut tissues were similar for all treatments. Thus, the addition of A. nodosum seaweed to well digestible diets did not enhance performances of piglets nor some gut health parameters and plasma oxidative status.

Fermented liquid feed for pigs: an ancient technique for the future

Fermented liquid feed is feed that has been mixed with water at a ratio ranging from 1:1.5 to 1:4. By mixing with water, lactic acid bacteria and yeasts naturally occurring in the feed proliferate and produce lactic acid, acetic acid and ethanol which reduces the pH of the mixture. This reduction in pH inhibits pathogenic organisms from developing in the feed. In addition, when this low pH mixture is fed, it reduces the pH in the stomach of pigs and prevents the proliferation of pathogens such as coliforms and Salmonella in the gastrointestinal tract. For piglets, the use of fermented liquid feed offers the possibility of simultaneously providing feed and water, which may facilitate an easier transition from sow’s milk to solid feed. Secondly, offering properly produced fermented liquid feed may strengthen the role of the stomach as the first line of defense against possible pathogenic infections by lowering the pH in the gastrointestinal tract thereby helping to exclude enteropathogens. Finally, feeding fermented liquid feed to pigs has been shown to improve the performance of suckling pigs, weaner pigs and growing-finishing pigs. In this review, current knowledge about the use of fermented liquid feed in pig diets will be discussed. This will include a discussion of the desirable properties of fermented liquid feed and factors affecting fermentation. In addition, advantages and disadvantages of fermented liquid feed will be discussed including its effects on gastrointestinal health, intestinal pH and the types of bacteria found in the gastrointestinal tract as well as the effects of fermented liquid feeds on pig performance.

Effect of Organic Acids on Salmonella Colonization and Shedding in Weaned Piglets in a Seeder Model

Piglets (n = 128) weaned at 21 days of age were used in a 35-day seeder model to evaluate the effects of dietary additives differing in active ingredients, chemical, and physical formulation, and dose on Salmonella colonization and shedding and intestinal microbial populations. Treatments were a negative control (basal diet), the positive control (challenged, basal diet), and six treatments similar to the positive control but supplemented with the following active ingredients (dose excluding essential oils or natural extracts): triglycerides with butyric acid (1.30 g kg(-1)); formic and citric acids and essential oils (2.44 g kg(-1)); coated formic, coated sorbic, and benzoic acids (2.70 g kg(-1)); salts of formic, sorbic, acetic, and propionic acids, their free acids, and natural extracts (2.92 g kg(-1)); triglycerides with caproic and caprylic acids and coated oregano oil (1.80 g kg(-1)); and caproic, caprylic, lauric, and lactic acids (1.91 g kg(-1)). On day 6, half the piglets (seeder pigs) in each group were orally challenged with a Salmonella Typhimurium nalidixic acid-resistant strain (4 × 10(9) and 1.2 × 10(9) log CFU per pig in replicate experiments 1 and 2, respectively). Two days later, they were transferred to pens with an equal number of contact pigs. Salmonella shedding was determined 2 days after challenge exposure and then on a weekly basis. On day 34 or 35, piglets were euthanized to sample tonsils, ileocecal lymph nodes, and ileal and cecal digesta contents. The two additives, both containing short-chain fatty acids and one of them also containing benzoic acid and the other one also containing essential oils, and supplemented at more than 2.70 g kg(-1), showed evidence of reducing Salmonella fecal shedding and numbers of coliforms and Salmonella in cecal digesta. However, colonization of tonsils and ileocecal lymph nodes by Salmonella was not affected. Supplementing butyric acid and medium-chain fatty acids at the applied dose failed to inhibit Salmonella contamination in the current experimental setup.

Effect of Organic Acids on Salmonella Shedding and Colonization in Pigs on a Farm with High Salmonella Prevalence.

This study builds on the results of a previous study in which six commercial feed products based on organic acids were evaluated with respect to Salmonella contamination of piglets in an artificially challenged seeder model. In the present study, the efficacy of three of these commercial products was assessed for Salmonella reduction in fattening pigs on one closed farm with a natural high Salmonella prevalence. In each of four fattening compartments, one of the following feed treatments was evaluated during two consecutive fattening rounds: (i) butyric acid (active ingredients at 1.3 kg/ton of feed; supplement A1), (ii) a combination of short-chain organic acids (mixture of free acids and salts) and natural extracts (2.92 kg/ton; supplement A4), (iii) a 1:1 blend of two commercial products consisting of medium-chain fatty acids, lactic acid, and oregano oil (3.71 kg/ton; supplement A5+A6), and (iv) a control feed. On the farm, the Salmonella status of the fattening pigs was evaluated by taking fecal samples twice during the fattening period. At the slaughterhouse, samples were collected from the cecal contents and the ileocecal lymph nodes. Salmonella isolates were serotyped and characterized by pulsed-field gel electrophoresis. This farm had a particularly high number of pigs shedding Salmonella with a wide variety of sero- and pulsotypes. Only the feed blend based on the medium-chain fatty acids was able to significantly reduce Salmonella prevalence both on the farm and at the slaughterhouse. With this combined supplement, the Salmonella reduction in the feces at slaughter age, in cecal contents at slaughter, and the lymph nodes was 50, 36, and 67%, respectively, compared with the control animals. This promising finding calls for further investigation including cost-efficiency of this combined feed product and its effect on the animals.

Effect of fermented moist feed on performance, gut bacteria and gut histo-morphology in broilers

1. Fermented feed has been shown to be beneficial in pig nutrition as a tool to reduce gut microbial disorders. Experiments with fermented feed in poultry are scarce, probably because of the belief that wet feed is less suitable for this species and causes wet litter. 2. A total of 280 one-d-old Ross 308 chickens were used in a completely randomised design with two dietary treatments (7 replicates of 20 birds/treatment); air-dry feed versus the same feed in moist form (water:feed ratio of 1.3:1, on a weight basis), inoculated with Lactobacillus plantarum NCIMB 40087 (9 log10 CFU/kg feed) and batch-fermented for 48 h at 26°C. The birds were given starter (d 0–13), grower (d 4–26) and finisher (d 27–39) diets ad libitum. At the end of the grower and finisher period, two birds per pen were removed to sample intestinal contents for cultivating bacteria and intestinal tissue to determine villus height and crypt depth. 3. Fermented moist feed (FMF) batches showed good characteristics, with a pH between 3.9 and 4.4 and DL-lactic acid between 137 and 286 mmol/l. Daily feed intake and gain were reduced considerably in the FMF group in the starter (–40 and –44%, respectively) and grower (–23 and –16%) period, though in the finisher period these birds performed better, with an improved feed utilisation. Concomitant with the latter, villus height at the mid-jejunum and mid-ileum on d 39 was higher (+22.6% and +16.0%). Significantly more Lactobacilli and less coliforms were found in the foregut and less Streptococci in ileum and caeca of birds given FMF. 4. This trial showed that FMF was detrimental for early bird growth but affected beneficially feed efficiency, the composition of the gut bacteria and villus height in the small intestine in the finisher period in broilers.

The effect of different concentrations of linseed oil or fish oil in the maternal diet on the fatty acid composition and oxidative status of sows and piglets.

N-3 polyunsaturated fatty acids (PUFA) are essential for foetal development. Hence, including n-3 PUFA in the sow diet can be beneficial for reproduction. Both the amount and form (precursor fatty acids vs. long chain PUFA) of supplementation are important in this respect. Furthermore, including n-3 PUFA in the diet can have negative effects, such as decreased arachidonic acid (ARA) concentration and increased oxidative stress. This study aimed to compare the efficacy to increase eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations in the piglet, when different concentrations of linseed oil (LO, source of precursor α-linolenic acid) or fish oil (FO, source of EPA and DHA) were included in the maternal diet. Sows were fed a palm oil diet or a diet including 0.5% or 2% LO or FO from day 45 of gestation until weaning. Linoleic acid (LA) was kept constant in the diets to prevent a decrease in ARA, and all diets were supplemented with α-tocopherol acetate (150 mg/kg) and organic selenium (0.4 mg/kg) to prevent oxidative stress. Feeding 0.5% LO or 0.5% FO to the sows resulted in comparable EPA concentrations in the 5-day old piglet liver, but both diets resulted in lower EPA concentrations than when 2% LO was fed. The highest EPA concentration was obtained when 2% FO was fed. The DHA level in the piglet liver could only be increased when FO, but not LO, was fed to the sows. The 2% FO diet had no advantage over the 0.5% FO diet to increase DHA in the piglet. Despite the constant LA concentration in the sow diet, a decrease in ARA could not be avoided when LO or FO were included in the diet. Feeding 2% FO to the sows increased the malondialdehyde concentration (marker for lipid peroxidation) in sow plasma, but not in piglets.

Fermented liquid feed for weaned piglets: impact of sedimentation in the feed slurry on performance and gut parameters

In two experiments with weaned piglets, the effects of fermented liquid feed (FLF) (produced with probiotic strain Pediococcus acidilactici, Bactocell®, Lallemand S.A.S.) on performance and some bacteriological and morpho-histological parameters of the gut were investigated, and the impact of sedimentation of the solids in the FLF thereon. In experiment I, FLF or the same dry feed (DRY) was offered ad libitum for 28 days to two groups of 15 weaned piglets (28 days of age) each (3 replicates of 5 pigs). Performance was negatively affected by feeding FLF and concomitant with that the group fed the FLF diet showed shorter villi (501 vs 550 μm) and smaller crypts (264 vs 289 μm) in the small intestine at 3 m proximal to the caecum (P < 0.05). It was assumed that these poorer results were due to sedimentation of the solids in the FLF and therefore a second experiment was conducted with sepiolite (10 g/kg) added to the feeds. Sepiolite tends to slow down the segregation of particles in slurry. The three feeding groups (weaned piglets, 27 days of age) in this experiment were DRY, DRY with probiotic (DRY+), and FLF. The group fed FLF (body weight gain (BWG) 254 g/piglet day; feed : gain ratio 1.38) did now perform better (P < 0.05) than the groups fed the DRY (BWG 184 g/piglet/day; feed : gain ratio 1.52) and DRY+ (BWG 185 g/piglet/day; feed : gain ratio 1.48) diets, which did not differ. Villus length in the small intestine at 3 m proximal to the caecum was also higher for the group fed FLF (558 μm) compared with the group fed the DRY+ diet (490 μm; P < 0.05). It was concluded that feeding FLF is beneficial to freshly weaned piglets on condition that sedimentation of the solids in the feed slurry can be controlled.

Effects of birth weight and maternal dietary fat source on the fatty acid profile of piglet tissue.

This study aimed to investigate the effects and possible interactions of birth weight and n-3 polyunsaturated fatty acid (PUFA) supplementation of the maternal diet on the fatty acid status of different tissues of newborn piglets. These effects are of interest as both parameters have been associated with pre-weaning mortality. Sows were fed a palm oil diet or a diet containing 1% linseed, echium or fish oil from day 73 of gestation. As fish oil becomes a scarce resource, linseed and echium oil were supplemented as sustainable alternatives, adding precursor fatty acids for DHA to the diet. At birth, the lightest and heaviest male piglet per litter were killed and samples from liver, brain and muscle were taken for fatty acid analysis. Piglets that died pre-weaning had lower birth weights than piglets surviving lactation (1.27±0.04 v. 1.55±0.02 kg; P<0.001), but no effect of diet on mortality was found. Lower DHA concentrations were observed in the brain of the lighter piglets compared with their heavier littermates (9.46±0.05 v. 9.63±0.04 g DHA/100 g fatty acids; P=0.008), suggesting that the higher incidence of pre-weaning mortality in low birth weight piglets may be related to their lower brain DHA status. Adding n-3 PUFA to the sow diet could not significantly reduce this difference in DHA status, although numerically the difference in the brain DHA concentration between the piglet weight groups was smaller when fish oil was included in the sow diet. Independent of birth weight, echium or linseed oil in the sow diet increased the DHA concentration of the piglet tissues to the same extent, but the concentrations were not as high as when fish oil was fed.