Near-Infrared (NIR) Spectroscopy as an Alternative for Predicting n-Alkane Concentration in Excreta of Laying Hens: NIR-Generated Data for Dietary Composition Estimation.

N-alkanes offer a promising approach for assessing the nutritional contribution of external sources to the diets of laying hens in free-range production systems. However, traditional laboratory methods, involving extraction, purification and gas chromatographic analysis, are both economically burdensome and time-consuming. Near-infrared spectroscopy (NIRS) is emerging as a viable alternative, with varying degrees of accuracy depending on the chemical nature and concentration of the component of interest. In our research, we focus on the accuracy of NIRS in predicting the concentrations of n-alkanes (C25-C33) in excreta under simulated free-range conditions with two different diets: one containing a commercial feed with minimal n-alkane content and another containing 1% alfalfa on top of the commercial feed. Spectra processing and calibration were tailored for each n-alkane, with NIRS performance influenced by diet type. Notably, plant predictions using NIR-generated data were consistent with laboratory results, despite a slight tendency toward overestimation (3.40% using the NIRS-generated C25-C29-C33 combination versus 2.80% using laboratory analysis). This indicates the potential of NIRS as an efficient tool to assess n-alkanes in excreta of laying hens and, consequently, the nutritional contribution of the free-range environment, providing rapid and cost-effective results.

Quantitative and Qualitative Evaluation of Plant Intake in Laying Hens: n-Alkanes as Predictive Fecal Markers for Dietary Composition Assessment.

The shift in animal welfare standards towards free-range housing for laying hens in the EU has raised questions about changes in dietary composition. Accurate assessment of outdoor plant material intake is crucial for effective feeding strategies. This study introduces an approach using n-alkanes as markers to determine plant intake in laying hens, involving n-alkane recovery rate assessment, discriminant analysis and linear equation-solving for both qualitative and quantitative assessment, respectively, considering systematic n-alkane combinations. Two diets: a standard commercial diet and a diet incorporating 1% alfalfa were tested. Chemical analyses showed an altered n-alkane profile due to alfalfa inclusion, resulting a recovery rates ranging from 30-44% depending on the n-alkane type and diet. Statistical analysis revealed significant differences in recovery rates among the different alkanes for the same diets and between the diets for the same alkane, together with an interaction between n-alkane carbon chain length and initial concentration in the diet. The method accurately predicted plant inclusion, with a slight overestimation (2.80%) using the combination C25-C29-C33. Accurate qualitative classification of the animals based on fecal n-alkanes profiles was observed. The study successfully demonstrated the utility of n-alkanes for estimating dietary composition, providing a non-invasive approach for future free-range studies.

Antimicrobial Activity of Peptides Produced by Lactococcus lactis subsp. lactis on Swine Pathogens.

Swine production is of great importance worldwide and has huge economic and commercial impact. Due to problems with bacterial infection, the use of antimicrobials has increased in the last decades, particularly in Latin America and Asia. This has led to concerns about antimicrobial resistance, which poses risks to human health and the environment. The use of probiotic organisms has been proposed as an alternative to this use, as these beneficial bacteria can produce antimicrobial peptides, such as bacteriocins, which allow the induction of inhibitory effects against pathogenic microorganisms. Among probiotics, some bacteria stand out with the inhibition of animal pathogens. The bacteriocin-like inhibitory substances (BLISs) of Lactococcus lactis subsp. lactis strain L2, present in its cell-free supernatant, were tested against pathogenic strains isolated from pig samples, such as Escherichia coli, Salmonella enterica, Streptococcus suis, Streptococcus dysgalactiae, Staphylococcus hyicus, and Enterococcus faecalis. Compounds secreted by L. lactis L2 have been shown to inhibit the growth of some pathogenic species, particularly Gram-positive bacteria, with S. suis being the most prominent. Antimicrobial peptides with a molecular size of 500-1160 Daltons were isolated from BLISs. The results highlight the potential of L. lactis BLISs and its peptides as natural antimicrobials for use in the food industry and to reduce the use of growth promoters in animal production.

Influence of Expander Conditioning Prior to Pelleting on Pellet Quality, Broiler Digestibility and Performance at Constant Amino Acids Composition while Decreasing AMEN.

Physical pellet quality and AMEN concentration are strongly related to each other in broiler feeding. A study was conducted to evaluate the relationship between dietary AMEN concentration and feed processing on pellet quality, nutrient digestibility, broiler performance, serum markers, and yield of commercial cuts. Six diets were formulated. The first diet had the recommended AMEN concentration, each further diet was calculated with 40 kcal/kg less, from 0 to −200 kcal/kg, resulting in six levels for each feed phase: starter (1−14 d), grower (15−28 d), and finisher (29−35 d). These diets were processed with and without expander conditioning prior to pelleting, using an average corn particle size of 1.6 mm, ground with a roller mill. A total of 1008 one-day-old male Ross 308 broiler chickens were placed in a 6 × 2 (6 energy levels and 2 conditionings) factorial trial with six boxes as replications, with three in each broiler performance trial period. Excreta were collected 2 days before the end of each feed phase for apparent total tract digestibility measurement. On day 36, four broilers from each replication (pen) were weighed and then euthanized for blood collection, following which the gastrointestinal organs were weighed, and the ileal and gizzard contents were collected. On day 37, all remaining broilers were slaughtered after fasting to measure commercial cuts and abdominal fat. The results show that the pellet durability index (PDI) was most affected by energy reducing and expander conditioning prior to pelleting, and it was better when diets had energy reduced by 40 to 200 kcal/kg (p > 0.001), as when expander conditioning was used. Digestibility of nutrients was slightly affected by treatments, as was the broiler performance; however, feed efficiency was improved in broiler-fed diets without AMEN reduction and when an expander was used, with p = 0.050 and p = 0.031, respectively. No effects were observed on the weight of gastrointestinal tract organs and serum markers, except for liver (p = 0.037) and α-amylase (p = 0.047). The lowest liver weight and lowest serum protein, cholesterol, triglyceride, gamma-glutamyl, and lipase concentrations were obtained when diets were formulated without energy reduction (Ross-0). There was no effect on commercial cuts relative to live weight at slaughter. The energy reduction was well reflected in the proportion of abdominal fat, which decreased when AMEN was reduced (p = 0.001). The present study shows it is possible to use diets with up to 200 kcal/kg reduction in AMEN without losses in performance, and the use of expander conditioning prior to pelleting promotes higher pellet quality and broiler feed efficiency.

Towards Large Particle Size in Compound Feed: Using Expander Conditioning Prior to Pelleting Improves Pellet Quality and Growth Performance of Broilers.

During the processing of compound feed for broilers, several changes occur that affect the physical and probably the nutritional properties of pellets, influencing animal performance. The effects of mill type, particle size (PS) and expander conditioning prior to pelleting (E + P) were combined to generate pellets. A 2 × 3 × 2 factorial arrangement was designed with two mill types (a hammer mill (HM) or roller mill (RM)), three PSs (0.8, 1.2 or 1.6 mm) and two E + Ps (with or without expander processing prior to pelleting), with six replications of 12 unsexed Ross 308 broilers each. All the processing lines reduced the PS from mash to finished pellets via secondary grinding, by 2.35 times on average. However, RM grinding required less electric power (p < 0.001). The intended PS (0.8, 1.2 or 1.6 mm) did not affect this energy consumption. E + P and the PS interacted for the pellet durability index (PDI) (p = 0.006). The worst PDI in the pellets was observed when a PS of 1.6 mm without E + P was used. Only E + P positively affected starch (p < 0.001) and amino acids' ileal apparent digestibility (p < 0.01). Organic matter (OM) (p = 0.02) and fat (p < 0.001) digestibility, as well as AMEN (p = 0.005) content, were influenced by the PS (main effect), whereas E + P and mill type interacted with these values (p < 0.005). Lower OM digestibility and AMEN content were observed when RM without E + P was used (p = 0.001). The feed conversion ratio (FCR) was enhanced and feed intake (FI) was improved with E + P. The combination of the RM mill, a 1.6 mm mean PS, and E + P improved FCR (three-way interaction, p = 0.019)), showing that for a higher PS, E + P is necessary for animal performance. Carcass yield was, on average, 80.1%. No effects on commercial cuts (breast, legs and wings) were observed. In contrast, abdominal fat was affected by mill type * PS (p = 0.012) and E + P * PS (p = 0.048) in a two-way interaction. The highest abdominal fat indicated an imbalance in the amino acid (AA)-to-AMEN ratio. Coarse PS promoted heavier gizzards (p = 0.02) but E + P tended to reduce them (p = 0.057). The processing steps improved pellet quality and feed efficiency associated with RM, coarse PS and E + P, highlighting the positive effects of E + P on abdominal fat and AMEN content, which should be adjusted to AA or reduced at formulation. However, these results are for an experimental processing plant and may not necessarily apply to larger plants, so the use of these data and methods should be considered as guidelines for replication at production sites.

Influence of Insoluble Dietary Fibre on Expression of Pro-Inflammatory Marker Genes in Caecum, Ileal Morphology, Performance, and Foot Pad Dermatitis in Broiler.

In a low-fibre diet destined for broilers, the effects of two lignocellulose products and soybean hulls were evaluated regarding their effect on ileal morphometric parameters, caecal gene expression, foot pad dermatitis, and performance. A total of 5040-day-old broilers (Ross 308) were allotted to four treatments and fattened for 36 days applying a three-phase feeding program. The control diet consisted of corn, wheat, and soybean meal. Experimental diets were supplemented with 0.8% lignocellulose product 1, 0.8% lignocellulose product 2, or 1.6% soybean hulls. Tissue samples for caecal expression of inflammation-related genes and ileal morphometries were collected on day 21. Gizzard pH and weights were recorded, and foot pad scores were evaluated at day of slaughter (day 36). In starter (day 1−10) and finisher phase (day 28−36), no effect on the performance was observed. In grower phase (day 11−27), fibre-supplemented diets showed significantly heavier body weights and daily weight gains (p < 0.05). Daily feed intake, feed conversion ratio, and gene expression analysis were unaffected by dietary fibre supplementation. Positive effects regarding ileal morphometrics (higher villi) and foot pad health occurred in fibre-supplemented diets. In conclusion, fibre supplementation improved performance in grower phase and showed beneficial effects regarding ileal morphology and foot pad dermatitis.

Evaluation of a Dietary Grape Extract on Oxidative Status, Intestinal Morphology, Plasma Acute-Phase Proteins and Inflammation Parameters of Weaning Piglets at Various Points of Time.

Reports of the underlying mechanisms of dietary grape extract (GE) in overcoming weaning challenges in piglets have been partly inconsistent. Furthermore, evaluations of the effects of GE at weaning in comparison to those of widely used therapeutic antibiotics have been scarce. To explore the mode of action of GE in selected tissues and plasma, we evaluated gut morphology, antioxidant and inflammation indices. Accordingly, 180 weaning piglets were allocated to three treatment groups: negative control (NC), NC and antibiotic treatment for the first 5 days of the trial (positive control, PC), and NC and GE (entire trial). The villus surface was positively affected by GE and PC on day 27/28 of the trial in the jejunum and on day 55/56 of the trial in the ileum. In the colon, NC tended (p < 0.10) to increase crypt parameters compared to PC on day 55/56. The PC group tended (p < 0.10) to increase catalase activity in the ileum and decrease Cu/Zn-SOD activity in the jejunum, both compared to NC. There were no additional effects on antioxidant measurements of tissue and plasma, tissue gene expression, or plasma acute-phase proteins. In conclusion, GE supplementation beneficially affected the villus surface of the small intestine. However, these changes were not linked to the antioxidant and anti-inflammatory properties of GE.

Suitability of Hermetia illucens larvae meal and fat in broiler diets: effects on animal performance, apparent ileal digestibility, gut histology, and microbial metabolites.

BACKGROUND: The possibility of partially replacing soybean meal (SBM) with Hermetia illucens (HI) defatted larvae meal in broiler nutrition has frequently been suggested. For sustainability reasons, however, the larvae fat produced during defatting should also be used and could be particularly beneficial regarding gut health due to its fatty acid composition. To evaluate the suitability of HI larvae as protein and fat source, a 2 × 3 factorial arrangement with two types of protein, i.e. SBM (S) or SBM and 15% of its crude protein replaced by HI larvae meal (L), and three levels of fat sources, namely 0 (0 L), 50% (50 L) or 100% HI larvae fat (100 L) at the expense of soybean oil was applied. RESULTS: In the starter phase, an interaction showed higher body weight (BW), average daily gain (ADG) and improved feed conversion ratio (FCR) if 50% or 100% HI larvae fat was fed with HI larvae meal. Moreover, BW, ADG and FCR improved when feeding HI larvae meal as protein source. Additionally, we observed an increased average daily feed intake in the grower, finisher, and overall phase in the L groups and an improved FCR in 0 L compared to 50 L groups during the overall period. Regarding apparent ileal digestibility, HI larvae meal feeding increased dry matter, organic matter, and fat digestibility. Feeding HI larvae meal as protein source decreased the concentrations of agmatine, spermidine, spermine and ammonia in the caecal digesta, whereas fat source affected agmatine with higher concentrations in 50 L compared to 0 L in the colonic digesta. In contrast, caecal ethanolamine concentrations increased in HI larvae meal groups compared to SBM. Caecal butyric acid concentrations decreased with HI larvae meal feeding. An interaction was found for the jejunal villus area, being higher in L + 100 L compared to S + 100 L. Furthermore, L groups had greater villus width. CONCLUSIONS: A partial replacement of SBM with HI larvae meal and soybean oil with HI larvae fat in broiler diets without impairing animal performance or gut health seems possible. Feeding HI larvae meal affected broiler performance positively in the starter phase and improved apparent ileal digestibility.

Beneficial effects of probiotics on the pig production cycle: An overview of clinical impacts and performance.

In pig nutrition, antibiotics are used to promote growth and/or to treat diseases in order to improve animal performance. However, due to the potential risk of cross selective pressure for antibiotic resistance among bacterial pathogens, the development of new nutritional additives is needed. Among them, probiotics are of great interest since they could improve the immune response, maintain animal intestinal health, and improve nutritional efficiency. Studies with probiotics have also demonstrated their antimicrobial effects on several pathogenic strains, emphasizing that the form of administration can enhance the beneficial effects. In view of the promising advances in probiotic research, it is opportune to highlight their capacity to modulate health and improve performance at all stages of pig production. Therefore, in this review, we will discuss the benefits of probiotics on physiological, immunological, and clinical aspects during different stages of the pig's life cycle. Specifically, probiotics improve performance during pregnancy, parturition and lactation in sows, they can improve immunohematological parameters and defenses in the growing phase, they can influence the quality of meat in the finishing phase and can also help in the reduction of environmental pollutants.

Potential of Grape Extract in Comparison with Therapeutic Dosage of Antibiotics in Weaning Piglets: Effects on Performance, Digestibility and Microbial Metabolites of the Ileum and Colon.

Enteric diseases in piglets, such as post-weaning diarrhea (PWD), often require antibiotic treatment of the entire litter. Grape polyphenols may help overcome PWD and thereby reduce the need for antibiotics. The potential of a grape extract (GE; continuous in-feed supplementation) on performance of weaning piglets, compared with both negative (NC; corn-based diet) and positive control (PC; NC + in-feed antibiotic (amoxicillin) in a therapeutic dosage for day 1-day 5 post weaning) was assessed. Apparent total tract digestibility (ATTD) and microbial metabolites were also evaluated on two sampling points (day 27/28 and day 55/56). We assigned 180 weaning piglets (6.9 ± 0.1 kg body weight (BW)) to 6 male and 6 female pens per treatment with 5 piglets each. Animals from PC showed higher BW on day 13 compared with NC and GE, and a tendency for higher BW on day 56 (p = 0.080) compared to NC. Furthermore, PC increased the average daily feed intake in the starter phase (day 1-day 13), and the average daily gain in the early grower phase (day 14-day 24). Overall, GE improved the ATTD at the same level as PC (ash, acid-hydrolyzed ether extract), or at a higher level than PC (dry matter, organic matter, gross energy, crude protein, P). There were no effects on microbial metabolites apart from minor trends for lactic acid and ammonia. Dietary inclusion of GE may have beneficial effects compared to therapeutic antibiotics, as frequently used at weaning.

Effect of Graded Substitution of Soybean Meal by Hermetia illucens Larvae Meal on Animal Performance, Apparent Ileal Digestibility, Gut Histology and Microbial Metabolites of Broilers.

The usage of insects as an alternative protein source for broiler feeds may help to reduce the dependency on soybean meal (SBM) imports. Therefore, the present study aimed to evaluate the replacement of 15 (SL15) or 30% (SL30) of crude protein (CP) from SBM with Hermetia illucens (HI) defatted larvae meal regarding broiler performance, carcass traits, apparent ileal digestibility, intestinal morphology, and microbial metabolites. Concerning the performance, body weight was similar for the control (CON) and SL15, but lower for SL30 during all feeding phases. In addition, average daily feed intake was higher in SL15 and SL30 compared to CON in the starter phase, but this effect vanished during grower and finisher phase. The apparent ileal digestibility decreased for CP and some amino acids with increasing HI larvae meal in the diet. No or marginal alterations were observed for the intestinal morphometry as well as cecal microbial metabolites. In conclusion, partial replacement of 15% SBM CP with HI larvae meal in broiler diets without impairing animal performance or health seems possible. The growth suppression with 30% CP substitution may be caused by reduced apparent ileal digestibility but could not be clearly associated with adverse effects of hindgut fermentation or altered gut morphology.

Antibacterial and antifungal activity of crude and freeze-dried bacteriocin-like inhibitory substance produced by Pediococcus pentosaceus.

Pediococcus pentosaceus LBM 18 has shown potential as producer of an antibacterial and antifungal bacteriocin-like inhibitory substance (BLIS). BLIS inhibited the growth of spoilage bacteria belonging to Lactobacillus, Enterococcus and Listeria genera with higher activity than Nisaplin used as control. It gave rise to inhibition halos with diameters from 9.70 to 20.00 mm, with Lactobacillus sakei being the most sensitive strain (13.50-20.00 mm). It also effectively suppressed the growth of fungi isolated from corn grain silage for up to 25 days and impaired morphology of colonies by likely affecting fungal membranes. These results point out that P. pentosaceus BLIS may be used as a new promising alternative to conventional antibacterial and antifungal substances, with potential applications in agriculture and food industry as a natural bio-controlling agent. Moreover, cytotoxicity and cell death induction tests demonstrated cytotoxicity and toxicity of BLIS to human colon adenocarcinoma Caco-2cells but not to peripheral blood mononuclear cells, with suggests possible applications of BLIS also in medical-pharmaceutical applications.

Bacteriocin-like inhibitory substance of Pediococcus pentosaceus as a biopreservative for Listeria sp. control in ready-to-eat pork ham.

The growing demand of consumers for synthetic chemical-free foods has increased the search for natural preservatives such as bacteriocins and bacteriocin-like inhibitory substances (BLIS) to give them adequate microbiological safety, sensory characteristics, and shelf life. In this study, the antimicrobial activity of BLIS produced by Pediococcus pentosaceus ATCC 43200 was compared with that of nisin. Lactobacillus sakei ATCC 15521, Listeria seeligeri NCTC 11289, Enterococcus En2052 and En2865, and Listeria monocytogenes CECT 934 and NADC 2045 exhibited larger inhibition halos in BLIS-treated than in Nisaplin-treated samples, unlike Listeria innocua NCTC 11288. In artificially contaminated ready-to-eat pork ham, BLIS was effective in inhibiting the growth of L. seeligeri NCTC 11289 for 6 days (counts from 1.74 to 0.00 log CFU/g) and ensured lower weight loss (2.7%) and lipid peroxidation (0.63 mg MDA/kg) of samples compared with the control (3.0%; 1.25 mg MDA/kg). At the same time, coloration of ham samples in terms of luminosity, redness, and yellowness as well as discoloration throughout cold storage was not influenced by BLIS or Nisaplin taken as a control. These results suggest the potential use of P. pentosaceus BLIS as a biopreservative in meat and other food processing industries.

Effects of soybean hulls and lignocellulose on performance, nutrient digestibility, microbial metabolites and immune response in piglets.

A feeding trial with 96 piglets was performed to investigate the effect of added soluble (SDF) and insoluble dietary fibre (IDF) sources on performance, apparent total tract digestibility (ATTD), concentration of microbial metabolites and pro-inflammatory marker genes as indicators for immune response. Piglets were allotted to four treatments (T): T1 control, T2 with soybean hulls (IDF/SDF: 8.35) and T3 and T4 with two different kinds of lignocellulose (IDF/SDF: >70). Diets were isofibrous for their value of total dietary fibre to underline the particular physicochemical properties of fibre sources. No differences were observed regarding average daily feed intake, average daily gain (ADG), feed conversion ratio and body weight, while T2 expressed higher ADG in the grower phase (day 14-54) vs. T3. Soybean hulls (T2) resulted in higher ATTD of dry matter and organic matter vs. T4; ether extract vs. T1 and neutral detergent fibre vs. T1, T2 and T3. The concentration of short chain fatty acids did not differ among treatments. Ileal digesta in T2 generated higher amounts of cadaverine vs. T3 and T4, likewise T1 vs. T4. Finally, no impact on immune response was detected. In conclusion, soybean hulls affected ATTD positively and lignocellulose prevented the formation of cadaverine, no overall direct response of SDF nor of IDF for the inclusion level  were observed.

Application of nisin as biopreservative of pork meat by dipping and spraying methods.

Comparison between dipping and spraying methods to inhibit bacterial growth on artificially contaminated pork meat showed greater effectiveness of the latter method during the whole low-temperature one-week storage of product. These results suggest that the spraying method could be successful in directly applying antimicrobials to food products.

Physicochemical properties to support fibre characterization in monogastric animal nutrition.

BACKGROUND: The aim of the study was to rank conventionally used fibre rich feeds for their physicochemical properties and detect possible correlation between analytical fibre determinations. A total of 22 samples were analysed for proximate fibre values, soluble dietary fibre (SDF), insoluble dietary fibre (IDF), crude protein (CP) and crude ash (CA). Physicochemical properties were determined in vitro by hydration capacity (HC) [water holding capacity (WHC), water binding capacity (WBC), swelling property (SwP)] and buffering capacity [linear buffering rate (LBR)]. RESULTS: Fibre content and physicochemical properties varied markedly between the samples. HC was highest for beet pulp and lowest for rice and millet bran. Buffering capacity expressed minimum values for lignocelluloses and maximum values for rape seed hulls. The correlation of methods was positively between WBC, WHC and SwP (r ≤ 0.89; P ≤ 0.003) but not significant for HC and buffering capacity. SwP negatively correlated with crude fibre (CF), neutral detergent fibre (aNDFOM ) and IDF (r ≤ -0.48; P ≤ 0.05). WBC and SwP positively correlated with SDF (r ≤ 0.63; P ≤ 0.04). LBR was negatively correlated with CF, aNDFOM , IDF and total dietary fibre (r ≤ -0.55; P ≤ 0.02), but positively with CP (r = 0.53; P = 0.01). CONCLUSION: The determination of physicochemical properties is applicable to rank fibre rich feeds, some correlations between fibre analytical measurements and physicochemical properties were detected. © 2019 Society of Chemical Industry.

Antimicrobial activity of bacteriocin-like inhibitory substance produced by Pediococcus pentosaceus: from shake flasks to bioreactor.

Bacteriocins are peptides produced by various species of bacteria, especially lactic acid bacteria (LAB), which have a large spectrum of action against spoilage bacteria and foodborne pathogens. However, when not entirely characterized, they are alternatively called bacteriocin-like inhibitory substances (BLIS). Pediococcus pentosaceus ATCC 43200 grew and produced BLIS optimally when cultivated anaerobically in bioreactor for 24 h at 30 °C and 200 rpm in De Man, Rogosa and Sharp (MRS) medium supplemented with 1.5% peptone. Under such optimal conditions, the cell mass concentration (3.41 g/L) was 66% higher, the generation time (1.28 h) 38% shorter and the BLIS activity against different indicator strains significantly higher than in MRS medium without any supplement taken as a control, and the exponential phase started 4 h before. The agar diffusion method showed BLIS inhibition halos against LAB strains with diameter in the range 11.0-19.5 mm and specific areas between 377.1 and 2654.6 mm2/mL, while BLIS activity against Listeria strains was better quantified by the liquid medium assay that showed, for the fermented broth without any dilution, 100 and 50% inhibition of Listeria innocua and Listeria seeligeri growth, respectively. These results highlight the potential of P. pentosaceus BLIS as a natural antimicrobial for application in the food industry.

Pumpkin seed cake as a fishmeal substitute in fish nutrition: effects on growth performance, morphological traits and fillet colour of two freshwater salmonids and two catfish species.

The objectives of this study were to investigate the digestibility of pumpkin seed cake (PSC) for the rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), and effects on performance and product quality traits of four different fish species when PSC partially replaced fishmeal in extruded diets. A digestibility trial was carried out to determine apparent digestibility coefficients (ADC) for crude protein (CP), ether extract (EE) and gross energy (GE) of PSC fed to rainbow trout. In subsequent growth trials, effects on performance and morphological traits and fillet colour values of four different fish species [rainbow trout; brook trout, Salvelinus fontinalis (Mitchill, 1814); African sharptooth catfish, Clarias gariepinus (Burchell, 1822); and wels catfish, Silurus glanis (Linnaeus, 1758)] were evaluated when 60% of fishmeal protein of a reference diet was replaced by PSC protein (based on digestible CP). Nutrient ADC of PSC were high (CP: 89%, EE: 88% and GE: 84%). No significant effects on growth and only minor effects on fillet colour were detected in the trials. However, replacing fishmeal with PSC at the chosen level affected morphological traits and feed conversion in all four species to different extents. Replacement effects of PSC should be tested at lower levels of inclusion before conclusions are drawn on its suitability in fish diets.

Effect of an organic acids based feed additive and enrofloxacin on the prevalence of antibiotic-resistant E. coli in cecum of broilers.

Increasing antibiotic resistance is a major public health concern. Fluoroquinolones are used to treat and prevent poultry diseases worldwide. Fluoroquinolone resistance rates are high in their countries of use. The aim of this study was to evaluate the effect of an acids-based feed additive, as well as fluoroquinolone antibiotics, on the prevalence of antibiotic-resistant E. coli. A total of 480 broiler chickens (Ross 308) were randomly assigned to 3 treatments: a control group receiving a basal diet; a group receiving a feed additive (FA) based on formic acid, acetic acid and propionic acid; and an antibiotic enrofloxacin (AB) group given the same diet, but supplemented with enrofloxacin in water. A pooled fecal sample of one-day-old chicks was collected upon arrival at the experimental farm. On d 17 and d 38 of the trial, cecal samples from each of the 8 pens were taken, and the count of E. coli and antibiotic-resistant E. coli was determined.The results of the present study show a high prevalence of antibiotic-resistant E. coli in one-day-old chicks. Supplementation of the diet with FA and treatment of broilers with AB did not have a significant influence on the total number of E. coli in the cecal content on d 17 and d 38 of the trial. Supplementation with FA contributed to better growth performance and to a significant decrease (P ≤ 0.05) in E. coli resistant to ampicillin and tetracycline compared to the control and AB groups, as well as to a decrease (P ≤ 0.05) in sulfamethoxazole and ciprofloxacin-resistant E. coli compared to the AB group. Treatment with AB increased (P ≤ 0.05) the average daily weight compared to the control group and increased (P ≤ 0.05) the number of E. coli resistant to ciprofloxacin, streptomycin, sulfamethoxazole and tetracycline; it also decreased (P ≤ 0.05) the number of E. coli resistant to cefotaxime and extended spectrum beta-lactamase- (ESBL-) producing E. coli in the ceca of broilers.

Effects of grazing intensity and environmental factors on species composition and diversity in typical steppe of Inner Mongolia, China.

In the present study, we aim to analyze the effect of grazing, precipitation and temperature on plant species dynamics in the typical steppe of Inner Mongolia, P.R. China. By uncoupling biotic and abiotic factors, we provide essential information on the main drivers determining species composition and species diversity. Effects of grazing by sheep were studied in a controlled experiment along a gradient of seven grazing intensities (from ungrazed to very heavily grazed) during six consecutive years (2005-2010). The results show that plant species composition and diversity varied among years but were little affected by grazing intensity, since the experimental years were much dryer than the long term average, the abiotic constraints may have overridden any grazing effect. Among-year differences were predominantly determined by the abiotic factors of precipitation and temperature. Most of the variation in species dynamics and coexistence between C3 and C4 species was explained by seasonal weather conditions, i.e. precipitation and temperature regime during the early-season (March-June) were most important in determining vegetation dynamics. The dominant C3 species Stipa grandis was highly competitive in March-June, when the temperature levels were low and rainfall level was high. In contrast, the most common C4 species Cleistogenes squarrosa benefited from high early-season temperature levels and low early-season rainfall. However, biomass of Stipa grandis was positively correlated with temperature in March, when effective mean temperature ranges from 0 to 5°C and thus promotes vernalization and vegetative sprouting. Our results suggest that, over a six-year term, it is temporal variability in precipitation and temperature rather than grazing that determines vegetation dynamics and species co-existence of grazed steppe ecosystems. Furthermore, our data support that the variability in the biomass of dominant species, rather than diversity, determine ecosystem functioning. The present study provides fundamental knowledge on the complex interaction of grazing - vegetation - climate.