ORIGINAL ARTICLE: Brain and hypophyseal acetylcholinesterase activity of pubertal boars fed dietary fumonisin B1

The effects of dietary fumonisin B₁ (FB₁) on regional brain and hypophyseal activities of AChE (EC 3117), the enzyme which catalyses the hydrolysis of acetylcholine, were studied using 24 male Large White weanling pigs divided into four groups. Each group received one of the four diets containing 0.2, 5.0, 10.0 and 15.0 mg FB₁/kg in a 6‐month feeding trial. All animals were slaughtered at the end of the feeding trial; the brains and the hypophyses obtained were carefully dissected out. Significant (p < 0.05) influence of dietary FB₁ on regional brain and hypophyseal AChE activities were observed. The AChE activities in the pons, amygdala, hypothalamus and the medulla oblongata declined significantly (p < 0.05) with increased dietary FB₁ concentrations. The findings of this study suggest that diets containing 5.0 mg FB₁/kg and above significantly (p < 0.05) altered regional brain and hypophyseal AChE activities in the animals. Dietary exposure to FB₁ at a concentration of approximately 5.0 mg/kg or more for a 6‐month period is a potential health risk that may induce adverse physiological response resulting from altered brain neurochemistry in growing pigs.     

Growth performance and puberty attainment in growing pigs fed dietary fumonisin B1

Twenty‐four male weaned piglets assigned to four diets containing 5.0, 10.0, 15.0 and 0.2 mg fumonisin B₁ (FB₁) /kg as diets 1, 2, 3 and control diet, respectively, were used to study the effect of dietary FB₁ on growth and puberty attainment in pigs in a 6‐month feeding trial. Lower feed intake during 0–4 months and a non‐significant (p > 0.05) but FB₁ concentration‐dependent decrease in live and DWGs in animals fed FB₁‐contaminated diets was observed at the end of the pubertal phase. The daily and the final live weight gains of animals fed diet 3 were 75.8% and 90.6%, respectively, of the control values. The mean ages at puberty by boars on diets 2 and 3 were significantly (p < 0.05) higher than those for animals on the control and diet 1. The animals on diet 3 attained puberty when mean live weight was 60.1 kg, some 30.3 days after the controls attained puberty, at 156.3 days, when the mean live weight was 46.9 kg. This study revealed that dietary FB₁ delays sexual maturity in growing pigs. Male weanling pigs for breeding should not be exposed to dietary FB₁ higher than 5 mg/kg for optimum growth and reproductive performance.     

Effects of prolonged exposure to low-dose fumonisin B1 in pigs

From the point of view of human exposure, fumonisins (FB1, FB2, FB1, FB4), a relatively recently (1988) discovered and identified group of mycotoxins, represent one of the five most important mycotoxin groups causing human disease. In an earlier experiment studying the effects of relatively low doses (10, 20 and 40 p.p.m.) of FB1 in weaned piglets, it was established that the 4-week feeding of 10 p.p.m. (mg/kg feed) FB1 produced mild pulmonary oedema. This suggested the importance of studies with even lower doses of the toxin to determine the tolerable limits. The objective of this experiment was therefore to study the effects of prolonged (8-week) exposure to still lower concentrations (0, 1, 5 and 10 mg/kg feed) of FB1. The 8-week feeding of FB1 in low concentrations (1-10 p.p.m.) did not cause clinical signs and significant performance impairment in pigs, but rendered irreversible the chronic changes that had already developed in the animals in a dose-dependent manner. Dissection revealed pathological alterations of the lungs in one of the animals given 1 p.p.m. (n = 4), in two animals exposed to 5 p.p.m. (n = 5), and in three animals given 10 p.p.m. (n = 4). In all three treatment groups, proliferation of the connective tissue fibres, primarily of those around the lymphatic vessels, in the subpleural and interlobular connective tissue of the lungs, extending to the peribronchial and peribronchiolar areas, was seen. The results of this experiment call attention to the risk of prolonged low-dose toxin exposure, which has very important public health implications.     

The food contaminant fumonisin B1 reduces the maturation of porcine CD11R1+ intestinal antigen presenting cells and antigen-specific immune responses, leading to a prolonged intestinal ETEC infection

Consumption of food or feed contaminated with fumonisin B₁ (FB₁), a mycotoxin produced by Fusarium verticillioides, can lead to disease in humans and animals. The present study was conducted to examine the effect of FB₁ intake on the intestinal immune system. Piglets were used as a target and as a model species for humans since their gastro-intestinal tract is very similar. The animals were orally exposed to a low dose of FB₁ (1 mg/kg body weight FB₁) for 10 days which did not result in clinical signs. However, when compared to non-exposed animals, FB₁-exposed animals showed a longer shedding of F4⁺ enterotoxigenic Escherichia coli (ETEC) following infection and a lower induction of the antigen-specific immune response following oral immunization. Further analyses to elucidate the mechanisms behind these observations revealed a reduced intestinal expression of IL-12p40, an impaired function of intestinal antigen presenting cells (APC), with decreased upregulation of Major Histocompatibility Complex Class II molecule (MHC-II) and reduced T cell stimulatory capacity upon stimulation. Taken together, these results indicate an FB₁-mediated reduction of in vivo APC maturation.     

Quantitative morphology in canine cutaneous soft tissue sarcomas

Stained cytological specimens from 24 dogs with spontaneous soft tissue sarcomas [fibrosarcoma (n = 8), liposarcoma (n = 8) and haemangiopericytoma (n = 8)], and 24 dogs with reactive connective tissue lesions [granulation tissue (n = 12) and dermal fibrosis (n = 12)] were analysed by computer‐assisted nuclear morphometry. The studied morphometric parameters were: mean nuclear area (MNA; µm²), mean nuclear perimeter (MNP; µm), mean nuclear diameter (MND mean; µm), minimum nuclear diameter (D_min; µm) and maximum nuclear diameter (D_max; µm). The study aimed to evaluate (1) possibility for quantitative differentiation of soft tissue sarcomas from reactive connective tissue lesions and (2) by using cytomorphometry, to differentiate the various histopathological soft tissue sarcomas subtypes in dogs. The mean values of all nuclear cytomorphometric parameters (except for D_max) were statistically significantly higher in reactive connective tissue processes than in soft tissue sarcomas. At the same time, however, there were no considerable differences among the different sarcoma subtypes. The results demonstrated that the quantitative differentiation of reactive connective tissue processes from soft tissue sarcomas in dogs is possible, but the same was not true for the different canine soft tissue sarcoma subtypes. Further investigations on this topic are necessary for thorough explication of the role of quantitative morphology in the diagnostics of mesenchymal neoplasms and tumour‐like fibrous lesions in dogs     

Experimental Dual Infection of Specific Pathogen‐Free Pigs with Porcine Reproductive and Respiratory Syndrome Virus and Pseudorabies Virus

Twenty 6‐week‐old specific pathogen‐free pigs were divided into four groups. On day 0 of the experiment, PRRSV–PRV (n = 6) and PRRSV (n = 4) groups were intranasally inoculated with porcine reproductive and respiratory syndrome virus (PRRSV) (10^5.6 TCID₅₀). On day 7, the PRRSV–PRV and PRV (n = 6) groups were intranasally inoculated with pseudorabies virus (PRV) (10^3.6 TCID₅₀). Control pigs (n = 4) were kept as uninoculated negative controls. Half of the pigs in each group were euthanized and necropsied on day 14 or 21. Clinical signs such as depression and anorexia were observed in the PRRSV–PRV and PRV groups after inoculation with PRV. Although febrile response was observed after virus inoculations, the duration of that response was prolonged in the PRRSV–PRV group compared with the other groups. The lungs in the PRRSV–PRV group failed to collapse and were mottled or diffusely tan and red, whereas the lungs of the pigs in the other groups were grossly normal. Histopathologically, interstitial pneumonia was present in all PRRSV‐inoculated pigs, but the pneumonic lesions were more severe in the PRRSV–PRV group. Mean PRRSV titres of tonsil and lung in the PRRSV–PRV group were significantly (P < 0.05) higher than that in the PRRSV group on day 21. These results indicate that dual infection with PRRSV and PRV increased clinical signs and pneumonic lesions in pigs infected with both viruses, as compared to pigs infected with PRRSV or PRV only, at least in the present experimental conditions.     

Interaction between the three frequently co‐occurring Fusarium mycotoxins in rats

To test the complex, acute biochemical effects of combined, naturally co‐occurring fusariotoxins, a 5‐day rat study was performed. Mycotoxin treatment was invented by intraperitoneal injection: FB₁ (F): 9 µg/animal/day (approx. 30 µg/kg bw/day), DON (D): 16.5 µg/animal/day (approx. 55 µg/kg bw/day) and ZEN (Z): 12.75 µg/animal/day (approx. 42.5 µg/kg bw/day). The binary groups (FB₁ and DON [FD], FB₁ and ZEN [FZ] and DON and ZEN [DZ]) as well as the ternary (FB₁, DON and ZEN [FDZ]) group were dosed at the same combined level as the individual mycotoxins. Body weight, feed intake and mortality were not affected by any of the treatments. FB₁ and DON in combination (FD) increased the plasma aspartate aminotransferase activity synergistically (compared to the individual FB₁ and DON). In the liver, both the total glutathione (GSH) and the glutathione peroxidase (GPx) activity were increased (p < 0.05) by the binary FB₁ and ZEN (FZ) and the DON and ZEN (DZ) groups as well as the ternary FB₁, DON and ZEA group (FDZ) compared to the control. The GSH level of the ternary group was significantly increased compared to the FB₁ group, whereas the GPx activity of the ternary group was significantly increased compared to all three the individual mycotoxin groups. The Bliss independence method revealed synergism between DON and ZEN (DZ), as well as FB₁ and DON (FD) on liver GPx activity. None of the toxins alone or in combination exerted strong genotoxicity on lymphocytes, neither on the gross histopathological characteristics. However, even at these low levels acute exposure of more than one of these mycotoxins (FB₁, DON and ZEN) affected metabolic and detoxification changes.     

The Mycobiota and Toxicity of Equine Feeds

Feed contamination can lead to nutrient losses and detrimental effects on animal health and production. The purposes of this study were to investigate the mycobiota in equine mixed feeds and to determine natural contamination with aflatoxin B₁ (AFB₁) and fumonisin B₁ (FB₁). Fungal enumeration of equine feed samples was done. A commercially available enzyme-linked immunosorbent assay kit was applied to quantify AFB₁ and FB₁. A comparison between ELISA and HPLC was carried out. Feed mould counts ranged from <1× 10² to 1× 10⁵ cfu/g. The most frequent genus isolated was Aspergillus (40.54%), followed by Penicillium (18.38%) and Fusarium (16.22%). The most prevalent Aspergillus sp. was A. flavus (36%). AFB₁ values ranged between 0.01 and 99.4 μg/kg. FB₁ levels ranged between 0.01 and 7.49 μg/kg. HPLC and ELISA methods showed positive correlation for AFB₁ and FB₁ determinations (r = 0.9851 and r = 0.9791, respectively). The ELISA analytical method was efficient for AFB₁ and FB₁ detection. The scarcity of studies on natural fungal contamination and on the presence of AFB₁ and FB₁ in materials used as equine feed ingredients highlights the value and contribution of this study.     

Penetration of oxytetracycline into the nasal secretions and relationship between nasal secretions and plasma oxytetracycline concentrations after oral and intramuscular administration in healthy pigs

Bimazubute, M., Cambier, C., Baert, K., Vanbelle, S., Chiap, P., Gustin, P. Penetration of oxytetracycline into the nasal secretions and relationship between nasal secretions and plasma oxytetracycline concentrations after oral and intramuscular administration in healthy pigs. J. vet. Pharmacol. Therap. 34 , 176–183. The penetration of oxytetracycline (OTC) in plasma and nasal secretions of healthy pigs was evaluated during the first study, in response to oral dose of 20 mg of OTC per kg of body weight (bwt) per day as a 400 mg/kg feed medication (n = 5) and to intramuscular (i.m.)‐administered formulations at 10 mg/kg bwt (n = 5), 20 mg/kg bwt (n = 5), 40 mg/kg bwt (n = 5). Concentrations of OTC in plasma and nasal secretions were determined by a validated ultra‐high performance liquid chromatography associated to tandem mass spectrometry method (UPLC/MS/MS). The objectives were to select the efficacy treatment and to evaluate the possibility to predict nasal secretions concentrations from those determined in plasma. The animals were housed together in each experiment. In each group, the treatment was administered once daily during 6 consecutive days, and nasal secretions and plasma were collected after 4 and 24 h at day 2 and day 6. For oral administration, only one medicated feed was prepared and distributed to all the animals together and was consumed in approximately 1 h. To meet recommendations of efficacy for OTC in nasal secretions, only the i.m. of 40 mg/kg bwt associated to an inter‐dosing interval of 24 h provides and maintains concentrations in nasal secretions ≥1 μg/mL, appropriate to the MIC 50 and 90 of Pasteurella multocida and Bordetella bronchiseptica, respectively, the main pathological strains in nasal secretions. It has been demonstrated that, using a generalized linear mixed model (GLMM), OTC in the nasal secretions (μg/mL) can be predicted taking into account the OTC concentrations in plasma (μg/mL), according to the following equation: OTC_{nasal secretions} = 0.28 OTC_plasma?1.49. In a second study, the pharmacokinetic behaviour of OTC in plasma and nasal secretions of healthy pigs was investigated, after single‐dose i.m. of 40 mg/kg bwt of the drug. Blood samples and nasal secretions were collected at predetermined times after drug administration. The data collected in 10 pigs for OTC were subjected to non‐compartmental analysis. In plasma, the maximum concentration of drug (C_max), the time at which this maximum concentration of drug (T_max) was reached, the elimination half‐life (t½) and the area under the concentration vs. time curve (AUC) were, respectively, 19.4 μg/mL, 4.0, 5.1 h and 150 μg·h/mL. In nasal secretions, C_max, T_max, t½ and AUC were, respectively, 6.29 μg/mL, 4.0, 6.6 h and 51.1 μg·h/mL.     

Vaccination mitigates the impact of PRRSv infection on the pharmacokinetics of ceftiofur crystalline‐free acid in pigs

The pharmacokinetics of intramuscularly administered ceftiofur crystalline‐free acid (CCFA) were determined in pigs that were clinically healthy (n = 8), vaccinated with a Porcine reproductive and respiratory syndrome modified live virus (PRRS MLV) (n = 10), challenged with wild‐type porcine reproductive and respiratory syndrome virus (PRRSv) VR‐2385 (n = 10), or vaccinated with PRRS MLV and later challenged with wild‐type PRRSv VR‐2385 (n = 10). Animals were given a single dose of CCFA intramuscularly at 5 mg/kg body weight. Blood was collected at 0 (pretreatment), 0.25, 0.5, 1, 6, 12, 24, 48, 96, 144, 192, and 240 h postinjection. Plasma was analyzed using liquid chromatography‐mass spectrometry. Plasma concentration–time curves for each group were evaluated with noncompartmental modeling. When compared to control animals, those receiving the PRRSv wild‐type challenge only had a lower AUC_0‐last, higher Cl/F, and higher Vz/F. The PRRSv wild‐type challenge only group had the longest T_1/2λ. The C_max did not differ among all four treatments. Control animals had no statistically significant differences from animals vaccinated with PRRS MLV alone or animals vaccinated with PRRS MLV and later challenged with wild‐type PRRSv. Our results suggest that PRRSv wild‐type infection has the potential to alter CCFA pharmacokinetics and PRRS MLV vaccination may attenuate those changes.     

Noradrenergic Control of GnRH Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol

The present study investigates the influence of α₁‐adrenoreceptors in GnRH release in vitro and determines whether oestradiol modulates α₁‐adrenoreceptor‐GnRH interaction. Within 10 min after ewe sacrifice, saggital midline hypothalamic slices were dissected, placed in oxygenated Minimum Essential Media‐α (MEM‐α) at 4°C and within 2 h were singly perifused at 37°C with oxygenated MEM‐α (pH 7.4; flow rate 0.15 ml/min), either with or without oestradiol (24 pg/ml). After 4‐h equilibration, 10‐min fractions were collected for 4 h interposed with a 10‐min exposure at 60 min to specific α₁‐adrenoreceptor agonist (methoxamine) or antagonist (thymoxamine) at various doses (0.1–10 mm ). The α₁‐adrenoreceptor agonist (10 mm ) increased (p < 0.05) GnRH release at 90 min both in presence and absence of oestradiol. However, in presence of oestradiol, α₁‐adrenoreceptor agonist (10 mm )‐induced GnRH release remained elevated (p < 0.05) for at least 60 min. The bioactivity of the released GnRH was studied using a hypothalamus–pituitary sequential double‐chamber perifusion. Only after exposure of hypothalamic slices to α₁‐adrenoreceptor agonist (10 mm ), did the hypothalamic eluate stimulate LH release from pituitary fragments (n = 9, 7.8 ± 12.3–36.2 ± 21.6 ng/ml) confirming that the α₁‐adrenoreceptor agonist stimulated release of biologically active GnRH. In summary, GnRH release from the hypothalamus is under stimulatory noradrenergic control and this is potentiated in the presence of oestradiol.     

Noradrenergic Control of Arginine Vasopressin Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol

The present study aims at ascertaining the influence of α₁‐adrenoreceptors on arginine vasopressin (AVP) release in vitro and determine whether E₂ modulates the α₁‐adrenoreceptor and AVP interaction. Ten minutes after ewe killing, sagittal midline hypothalamic slices (from the anterior preoptic area to the mediobasal hypothalamus with the median eminence, 2 mm thick, 2 per sheep) were dissected, placed in oxygenated minimum essential media‐α (MEM‐α) at 4°C and within 2 h were singly perifused at 37°C with oxygenated MEM‐α (pH 7.4; flow rate 0.15 ml/min), either with or without E₂ (24 pg/ml). After 4 h equilibration, 10 min fractions were collected for 4 h interposed with 10 min exposure at 60 min to a specific α₁‐adrenoreceptor agonist or antagonist at various doses (0.1–10 mm ). At the end of all perifusions, slices responded to KCl (100 mm ) with AVP efflux (p < 0.05). Release of AVP was enhanced (p < 0.05) by the α₁‐adrenoreceptor agonist (methoxamine 10 mm ; no E₂, n = 7 perifusion chambers: from 14.3 ± 2.7 to 20.9 ± 3.9, with E₂, n = 10: from 10.7 ± 1.2 to 18.4 ± 3.4 pg/ml) or the antagonist (thymoxamine 10 mm ; no E₂, n = 5: from 9.5 ± 3.1 to 30.4 ± 6.0, with E₂, n = 10: from 10.8 ± 0.9 to 39.1 ± 6.3 pg/ml). With the agonist, the response occurred only at 80 min (p < 0.05) both in the presence and absence of E₂. Whereas, after the antagonist, values were higher (p < 0.05) throughout the post‐treatment period (80–170 min) without E₂, but declined by 150 min in the presence of E₂. Furthermore, the response to the α₁‐adrenoreceptor antagonist was greater (p < 0.05; 90–140 min) than the agonist only in the presence of E₂. In conclusion, these results reveal direct α₁‐adrenoreceptor‐mediated control of the hypothalamic AVP neuronal system which is modulated by E₂.     

Effects of high‐sulphur water on hepatic gene expression of steers fed fibre‐based diets

Sulphur‐induced polioencephalomalacia (sPEM), a neurological disorder affecting ruminants, is frequently associated with the consumption of high‐sulphur (S) water and subsequent poor performance. Currently, there is no economical method for S removal from surface water sources, and alternative water sources are typically neither readily available nor cost‐effective. Determination of genes differentially expressed in response to high‐S water consumption may provide a better understanding of the physiology corresponding to high dietary S and ultimately lead to the development of treatment and prevention strategies. The objective of this study was to determine changes in gene expression in the liver, an organ important for S metabolism, of fibre‐fed steers consuming high‐S water. For this study, liver tissues were collected on the final day of a trial from yearling steers randomly assigned to low‐S water control (566 mg/kg SO₄; n = 24), high‐S water (3651 mg/kg SO₄; n = 24) or high‐S water plus clinoptilolite supplemented at either 2.5% (n = 24) or 5.0% (n = 24) of diet dry matter (DM). Microarray analyses on randomly selected healthy low‐S control (n = 4) and high‐S (n = 4; no clinoptilolite) steers using the Affymetrix GeneChip Bovine Genome Array revealed 488 genes upregulated (p < 0.05) and 154 genes downregulated (p < 0.05) in response to the high‐ vs. low‐S water consumption. Real‐time RT‐PCR confirmed the upregulation (p < 0.10) of seven genes involved in inflammatory response and immune functions. Changes in such genes suggest that ruminant animals administered high‐S water may be undergoing an inflammation or immune response, even if signs of sPEM or compromised health are not readily observed. Further study of these, and other affected genes, may deliver new insights into the physiology underlying the response to high dietary S, ultimately leading to the development of treatments for high S–affected ruminant livestock.     

Protective effects of silymarin on fumonisin B1-induced hepatotoxicity in mice

The present study was conducted to investigate the effect of silymarin on experimental liver toxication induced by Fumonisin B₁ (FB₁) in BALB/c mice. The mice were divided into six groups (n = 15). Group 1 served as the control. Group 2 was the silymarin control (100 mg/kg by gavage). Groups 3 and 4 were treated with FB₁ (Group 3, 1.5 mg/kg FB₁, intraperitoneally; and Group 4, 4.5 mg/kg FB₁). Group 5 received FB₁ (1.5 mg/kg) and silymarin (100 mg/kg), and Group 6 was given a higher dose of FB₁ (4.5 mg/kg FB₁) with silymarin (100 mg/kg). Silymarin treatment significantly decreased (p < 0.0001) the apoptotic rate. FB₁ administration significantly increased (p < 0.0001) proliferating cell nuclear antigen and Ki-67 expression. Furthermore, FB₁ elevated the levels of caspase-8 and tumor necrosis factor-alpha mediators while silymarin significantly reduced (p < 0.0001) the expression of these factors. Vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) expressions were significantly elevated in Group 4 (p < 0.0001). Silymarin administration alleviated increased VEGF and FGF-2 expression levels (p < 0.0001). In conclusion, silymarin ameliorated toxic liver damage caused by FB₁ in BALB/c mice.     

Effects of flunixin meglumine and ketoprofen on mediator production in ex vivo and in vitro models of inflammation in healthy dairy cows

Donalisio, C., Barbero, R., Cuniberti, B., Vercelli, C., Casalone, M., Re, G. Effects of flunixin meglumine and ketoprofen on mediator production in ex vivo and in vitro models of inflammation in healthy dairy cows. J. vet. Pharmacol. Therap.  36 , 130–139. In this study, ex vivo assays were carried out in dairy cows to evaluate the anti‐inflammatory effects of two nonsteroidal anti‐inflammatory drugs: ketoprofen (KETO) and flunixin meglumine (FM). Twelve healthy Holstein dairy cattle were randomly allocated to two groups (n=6): group 1 received FM and group 2 received KETO at recommended therapeutic dosages. The anti‐inflammatory effects of both drugs were determined by measuring the production of coagulation‐induced thromboxane B₂ (TXB₂), lipopolysaccharides (LPS) (10 μg/mL)‐induced prostaglandin E₂ (PGE₂), and calcium ionophore (60 μm )‐induced leukotrien B₄ (LTB₄). Cytokine production was assessed by measuring tumor necrosis factor‐α (TNF‐α), interferon‐γ (IFN‐γ) and interleukin‐8 (CXCL8) concentrations after incubation in the presence of 10 μg/mL LPS. The IC₅₀ of FM and KETO was determined in vitro by determining the concentration of TXB₂ and PGE₂ in the presence of scalar drug concentrations (10^?9–10^?3 m ). Both FM and KETO inhibited the two COX isoforms in vitro, but showed a preference for COX‐1. FM and KETO showed similar anti‐inflammatory effects in the cow.     

Dietary protein concentration affects intestinal microbiota of adult cats: a study using DGGE and qPCR to evaluate differences in microbial populations in the feline gastrointestinal tract

The objective of this study was to identify qualitative and quantitative differences in microbial populations of adult cats fed diets containing different protein concentrations. Following a 4 week baseline period, eight healthy adult domestic short‐hair queens (>1‐year‐old) were randomly allotted to a moderate‐protein (MP; n = 4) or high‐protein (HP; n = 4) diet for 8 weeks. Fresh faecal samples were collected after baseline and 8 weeks on treatment and stored at ?80 °C. Following DNA extraction, samples were analyzed using denaturing gradient gel electrophoresis to distinguish qualitative changes between diets. Quantitative polymerase chain reaction was used to measure E. coli, Bifidobacterium, Clostridium perfringens, and Lactobacillus populations. Compared to baseline, cats fed MP had a bacterial similarity index of 66.7% as opposed to 40.6% similarity for those fed HP, exhibiting marked changes in intestinal bacteria of cats fed HP. Bifidobacterium populations were greater (p < 0.05) in cats fed MP versus HP (9.44 vs. 5.63 CFU/g). Clostridium perfringens populations were greater (p < 0.05) in cats fed HP than MP (12.39 vs. 10.83 CFU/g). In this experiment, a high‐protein diet resulted in a dramatic shift in microbial populations. Decreased Bifidobacterium population in cats fed HP may justify prebiotic supplementation for such diets.     

Antiviral Effect of Saccharomyces cerevisiaeβ‐glucan to Swine Influenza Virus by Increased Production of Interferon‐γ and Nitric Oxide

The aim of these experiments was to investigate the potential antiviral effect of Saccharomyces cerevisiaeβ‐glucan on the pneumonia induced by swine influenza virus (SIV). Forty colostrum‐deprived 5‐day‐old piglets were randomly divided into four groups of 10. The 20 pigs in groups 1 and 2 were administered Saccharomyces cerevisiaeβ‐glucan orally (50 mg/day/pig; En‐Bio Technology Co., Ltd) for 3 days before SIV infection and those in groups 3 and 4 were given culture medium/diluent alone. Groups 1 and 3 were inoculated intranasally with 3 ml of tissue culture fluid containing 2 × 10⁶ tissue culture infective doses 50% (TCID₅₀)/ml of SIV and those in groups 2 and 4 were exposed in the same manner to uninfected cell culture supernatant. The microscopic lung lesions induced by SIV infection (group 1 pigs) were significantly more severe than those induced by infection in animals pre‐administered β‐glucan (group 3) (P < 0.05). Significantly more SIV nucleic acid was detected in the lungs of pigs experimentally infected with SIV only (group 1) at 5, 7 and 10 days post‐inoculation (dpi) compared with lungs from pigs pre‐administered β‐glucan and infected with SIV (group 3) (P < 0.05). The concentrations of interferon‐γ (IFN‐γ) and nitric oxide (NO) in bronchoalveolar lavage fluid from pigs pre‐administered β‐glucan and infected with SIV (group 3) were significantly higher than for any other group at 7 and 10 dpi for IFN‐γ, and at 5, 7 and 10 dpi for NO (P < 0.05). Saccharomyces cerevisiaeβ‐glucan reduced the pulmonary lesion score and viral replication rate in SIV‐infected pigs. These findings support the potential application of β‐glucan as prophylactic/treatment agent in influenza virus infection.     

Mycobiota and mycotoxins contamination in raw materials and finished feed intended for fattening pigs production in eastern Argentina

The aim of the present study was to determine the mycobiota and natural levels of mycotoxins such as zearalenone, fumonisin B₁, aflatoxin B₁ and ochratoxin A present in raw materials and finished fattening pig feed. Samples were examined for total fungi and genera distribution. Zearalenone, FB₁, AFB₁ and OTA contamination were determined using high pressure liquid chromatography and thin layer chromatography. Milled maize and finished feed samples showed fungal contamination over than 1 × 10⁴ CFU/g. All samples contained at least one of the main mycotoxigenic genera Aspergillus, Fusarium and Penicillium. A. flavus and F. verticillioides were the most prevalent species. Only some Aspergillus section Nigri strains from suckling pig to growing pig samples were able to produce OTA. A. flavus strains from milled maize, wheat bran, suckling pig to growing pig samples were able to produce AFB₁. All samples were positive for FB₁. Sucking pig, piglet, growing and boar feed samples showed ZEA natural contamination. AFB₁ and OTA contamination were not detected. There was a 100% correlation between FB₁ and ZEA contamination in sucking pig, piglet, growing and boar feed samples; 50% piglet samples and 67% suckling pig samples showed ZEA levels over the recommended limits. The present study has shown the occurrence of two mycotoxins, FB₁ and ZEA in feed intended for fattening pig consumption. In animal production, the simultaneous presence of toxicogenic fungi and low dietary levels of mycotoxins in field conditions can cause possible health impacts and lost performance in pigs from feeding spoiled feeds.     

Animal‐Level Factors Affecting Ovarian Function in Bos indicus Heifers Treated to Synchronize Ovulation with Intravaginal Progesterone‐Releasing Devices and Oestradiol Benzoate

The primary objective of this study was to investigate the impact of animal‐level factors including energy balance and environmental/management stress, on the ovarian function of Bos indicus heifers treated to synchronize ovulation. Two‐year‐old Brahman (BN) (n = 30) and BN‐cross (n = 34) heifers were randomly allocated to three intravaginal progesterone‐releasing device (IPRD) treatment groups: (i) standard‐dose IPRD [Cue‐Mate^® (CM) 1.56 g; n = 17]; (ii) half‐dose IPRD [0.78 g progesterone (P₄); CM 0.78 g; n = 15]; (iii) half‐dose IPRD + 300 IU equine chorionic gonadotrophin at IPRD removal (CM 0.78 g + G; n = 14); (iv) and a control group, 2× PGF_2α [500 μg prostaglandin F_2α (PGF_2α)] on Day ?16 and ?2 (n = 18). Intravaginal progesterone‐releasing device‐treated heifers received 250 μg PGF_2α at IPRD insertion (Day ?10) and IPRD removal (Day ?2) and 1 mg oestradiol benzoate on Day ?10 and ?1. Heifers were managed in a small feedlot and fed a defined ration. Ovarian function was evaluated by ultrasonography and plasma P₄ throughout the synchronized and return cycles. Energy balance was evaluated using plasma insulin‐like growth factor 1 (IGF‐I) and glucose concentrations. The impact of environmental stressors was evaluated using plasma cortisol concentration. Heifers that had normal ovarian function had significantly higher IGF‐I concentrations at commencement of the experiment (p = 0.008) and significantly higher plasma glucose concentrations at Day ?2 (p = 0.040) and Day 4 (p = 0.043), than heifers with abnormal ovarian function. There was no difference between the mean pre‐ovulatory cortisol concentrations of heifers that ovulated or did not ovulate. However, heifers that ovulated had higher cortisol concentrations at Day 4 (p = 0.056) and 6 (p = 0.026) after ovulation than heifers that did not ovulate.     

Selection for food conversion in broilers: Predicted responses to selection for economic efficiency

1. Two selection indices which included a measure of food conversion efficiency in broiler production, were formulated: one index (I₁) used individual 9‐week body weight and 5‐ to 9‐week food consumption (FC); the other (I ₂) used individual 9‐week weight and sire‐family average food consumption (FC).

2. Three empirical parameter sets and 10 hypothetical data sets were used in calculating the indices and in predicting selection responses.

3. The three empirical parameter sets gave relatively similar index coefficients for I₁ which were proportional to the relative economic weightings to the two traits.

4. Predicted economic responses to selection based on I ₂ were negligibly superior to selection for body weight alone for nearly all data sets, whereas selection based on I₁ was always superior in economic response.

5. Predicted economic response to selection based on I₁ calculated from typical published estimates of genetic parameters was 20% greater than predicted response to selection for body weight alone.