Sodium Salicylate as Feed Additive in Broilers: Absence of Toxicopathological Findings

Antimicrobial growth promoters (AGPs) in animal production have been related to the increase in multidrug-resistant bacteria. The AGP ban in many countries has highlighted the growing need for alternatives for feed additives. Considering the non-antibiotic anti-inflammatory theory of AGPs, chicks received three different doses of sodium salicylate (SS) in feed (10, 30, 90 mg/kg), basal diet (BD) was used as a negative control, and zinc bacitracin (ZB) was used as a positive control. Chicks were individually housed to increase the accuracy of the dose of SS ingested. Performance parameters and footpad dermatitis were evaluated weekly, while haematology, serum biochemistry, histopathology, and tibial dyschondroplasia were determined on Days 21 and 42. A linear dose-dependent decrease in haemoglobin concentration was observed, but the values were within the normal reference range. Among all the other evaluated parameters, no relevant differences between treatments were observed; however, not even the AGP group performed better than the control group. It is possible that the conditions in which the birds were raised were not stressful enough to allow for anti-inflammatories to demonstrate their beneficial effects on performance. Studies should be conducted where the animals are exposed to commercial conditions, as the presence of natural stressors could allow a better evaluation of the efficacy of the anti-inflammatory agent as a growth promoter.

Potential immunomodulatory response associated with L-mimosine in male Wistar rats

Leucaena leucocephala is a plant that is used as animal and human food worldwide. This plant contains the toxic compound namely L-mimosine. The main mechanism of action of this compound involves its ability to chelate metal ions, which may interfere with the proliferative activity of cells and being studied for the treatment of cancer. However, little is known about the effect of L-mimosine on immune responses. Thus, the aim of this study was to evaluate the effects of L-mimosine on immune responses in Wistar rats. Different doses of L-mimosine (25, 40 and 60 mg/kg body weight/day) were administered orally by gavage to adult rats for 28 days. No clinical signs of toxicity were observed in animals, but a decrease in the T-dependent response to sheep red blood cells (SRBC) in animals treated with 60 mg/kg L-mimosine and an increase in the intensity of S. aureus phagocytosis by macrophages in animals treated with 40 or 60 mg/kg L-mimosine were observed. Therefore, these findings suggest that L-mimosine did not compromise macrophage activity and inhibited T-dependent clonal expansion during the immune response.

Potential toxic effects produced by L-mimosine in the thyroid and reproductive systems. Evaluation in male rats

Leucaena leucocephala is a worldwide plant used as forage; however, its use in animal production has been limited because of the presence of a toxic nonprotein amino acid, L-mimosine. L-mimosine exhibits negative effects not only in ruminants but also in monogastric animals; however, there is little information available on the effect of this amino acid in monogastric species. Thus, this study aimed to evaluate the general toxicity of L-mimosine in rats, as well as its effects on the endocrine and reproductive systems. L-mimosine was extracted from seeds of L. leucocephala that were administered orally by gavage to adult Wistar rats at different doses of 25, 40 and 60 mg/kg body weight/day for 28 days. The following parameters were evaluated: weight gain, feed intake, serum enzymes, histopathology (liver, kidney, thyroid, thymus, and spleen), serum hormones (testosterone, corticosterone, T3 and T4) and sexual behavior. No clinical signs of toxicity were observed in animals, but histopathology revealed consistent lesions in the thyroids. Additionally, rats exposed to L-mimosine presented low serum levels of testosterone, decreased mount numbers and increased mount intervals. Therefore, our study reinforces the assumption that L-mimosine has goitrogenic potential and causes impairment in male reproductive performance.

The effect of breed, sex, and drug concentration on the pharmacokinetic profile of ivermectin in cattle

Ivermectin (IVM) is one of the most widely used antiparasitic drugs worldwide and has become the drug of choice for anthelmintic and tick treatment in beef cattle production. It is known that pharmacokinetic parameters are fundamental to the rational use of a drug and food safety and these parameters are influenced by different factors. The aim of this study was to evaluate the pharmacokinetic profile of IVM in Bos indicus, Bos taurus, and crossbreed cattle (B. indicus × B. taurus) kept under same field conditions and the possible impacts of sex and IVM formulation (1% and 3.15%). It was observed that IVM concentration was significantly affected by breed. The plasma concentrations of IVM, AUC, C_max , and t_1/2β were significantly higher in B. indicus compared to B. taurus. Crossbreed animals showed an intermediate profile between European and Indian cattle. No alteration in pharmacokinetics parameters was detected when comparing different gender. Concerning the pharmacokinetic data of IVM formulation, it was verified that T_max , AUC, and t_1/2β were higher in 3.15% IVM animals than those from 1% IVM formulation. The results clearly indicated that the IVM plasma concentrations in B. indicus were higher than that in B. taurus.

Ivermectin does not interfere with seminal and hormonal parameters in male rabbits

Ivermectin (IVM) is a macrocyclic lactone used as a broad spectrum antiparasitic agent against nematodes and arthropods. It is mainly used in the control of parasitic infections of domestic animals, and recently has been used in humans to treat onchocerciasis, scabies, and pediculosis. In mammals, evidence has indicated that macrocyclic lactones interact with gamma-aminobutyric acid (GABA)-mediated chloride channels. The GABAergic system is known to be involved in the manifestation of sexual behavior, and previous studies have shown that IVM impaired sexual behavior in both male and female rats. Thus, considering that IVM may interfere with the sexual sphere, this study evaluated the temporal (1 up 60 days) effects of exposure to IVM (0.2 and 1.0 mg/kg, administered subcutaneously) on seminal and hormonal parameters of male rabbits. In male rabbits, the spermatozoa concentration, motility and morphology, the integrity of the plasmatic, acrosomal and mitochondrial membranes of the spermatozoa, the organ weights, gonadosomatic index, serum testosterone concentrations, histopathological findings were evaluated and hematological and serum biochemical analysis was conducted. No changes were observed in male seminal parameters evaluated by spermatozoa concentration, motility, and morphology, nor the potential for fertilization evaluated by the integrity of the plasmatic, acrosomal, and mitochondrial membranes of the spermatozoa; there was also no interference in serum testosterone concentration, serum biochemistry and hematological parameters. The findings of this study using the artificial vagina for collection of semen and computer-assisted semen analysis showed that IVM at doses of 0.2 and 1.0 mg/kg of SC did not alter any of the semen parameters of rabbits evaluated for up to 60 days after administration.

The effect of Cynara scolymus (artichoke) on maternal reproductive outcomes and fetal development in rats

Cynara scolymus (C.scolymus) is a plant employed worldwide as an herbal medicine. However, there is a paucity of data related to the evaluation of its toxicity in commercial preparations; thus, the aim of this study was to evaluate the possible teratogenic effect of the dry extract of C.scolymus leaves in Wistar rats. Females were treated, from gestation day (GD) 6 until GD19, with 0.0, 1.0, 2.0 or 4.0 g/kg body weight of C.scolymus extract. At GD20, a cesarean section was performed for evaluation of maternal and fetal parameters. C.scolymus did not induce changes in food consumption, preimplantation or postimplantation losses, placental weight or biochemical profile. An increase in water consumption was observed in pregnant females treated with the higher doses of C.scolymus. Experimental groups showed lower body weight gain during pregnancy and lower gravid uterus weight. Maternal body weight minus the gravid uterus weight did not result in significant differences. Reductions in fetal weight and length were observed in experimental groups. The number of live pups per litter was lower in the highest dose group. No fetal skeletal or visceral malformations were detected. The results showed that the consumption of artichoke during pregnancy clearly has a negative impact on fetuses.

Immunomodulatory effect of Cynara scolymus (artichoke) in rats

Cynara scolymus is a plant used both as food as well as medicinal plant worldwide. Cynarin is one of the main active principles of the plant, and it is also present in species such as Echinacea purpurae, which is known to have immunomodulatory activity. Thus, the objective of this study is to evaluate the immune effects of C. scolymus in rats. Rats were treated with 1.0-, 2.0-, or 4.0-g/kg body weight of C. scolymus extract for 28 days. Haemogram, serum biochemistry, lymphoid organs weight, and their cell phenotypes were evaluated. Macrophages and neutrophils oxidative burst, specific humoral immune response, and the delayed-type hypersensitivity (DTH) were studied. No changes in the haemogram, biochemical profile, antibody titers, lymphoid organs, and in their cellularities were observed. An increase in the basal activity of reactive oxygen species from male's macrophage was observed. There was a suppression of the DTH response in both gender when treated with the highest dose of C. scolymus. This study is the first in the literature that revealed an immunosuppressive effect of C. scolymus. We also verified that the doses of artichoke extract here employed did not cause general toxicity.

Maternal feed restriction during pregnancy in Wistar rats: Evaluation of offspring using classical and immunoteratology protocols

Studies have revealed that impairment of the pregnant body weight reduces the fetal body weight and causes minor changes in skeletal development. The aim of the present study was to assess the effects of maternal feed restriction during pregnancy in offspring immune system development. Pregnant Wistar rats were distributed into 5 groups: 1 control in which dams received food ad libitum and 4 experimental groups in which dams were fed restricted amounts of rodent ration (16, 12, 9, or 6 g/rat/day) from the 6th to 17th gestation day. Teratogenicity was assessed using classical teratological evaluation and developmental immunotoxicology protocols. Maternal body weight gain, fetus weight, and placenta weight were reduced for feed-restricted females from the groups fed 12, 9, and 6 g/rat/day ( p < 0.05). No pup mortality was observed immediately after cesarean sections among the groups, and no visceral or skeletal malformations were detected. An immunoteratological study revealed an increase in the relative weight of the thymus and an increase in the phorbol myristate-acetate solution-induced hydrogen peroxide release by inflammatory cells in 21-day-old pups. Alterations in the delayed-type hypersensitivity response and the humoral immune response against sheep red blood cells were observed in pups from feed-restricted mothers. Feed restriction in Wistar rats during organogenesis did not promote structural malformations but resulted in offspring with lower birth weights and promoted significant changes in the immune responses of the rat pups.