Evaluation of Short-term Myelotoxicity Study in Dietary Reduced Rats

This study attempted to prove our hypothesis that a short-term toxicity study, using a 4-day dosing regimen as an example, is suitable for evaluating myelotoxicity in rats. We compared the hematological, bone marrow cytological and histopathological results of 5-fluorouracil (5-FU) treated and pair-feeding groups after a 4-day administration period. Several experimental groups were defined for this 4-day study as well as for our previously reported 14-day study (Miyata et al., 2009); these included 5-FU treated groups receiving 12, 15 and 18 mg/kg/day (FU12, FU15 and FU18), pair-feeding groups (R12, R15 and R18 receiving the same amount of food as the FU12, FU15 and FU18 groups, respectively) and a nontreated control group. Although severe reductions in body weight gain and food consumption were reported in the 14-day study, only slight reductions were observed in the 4-day study. In the 4-day study, a decrease in blood reticulocytes and a decreasing trend of marrow erythroid cells were only observed in the FU18 group, and no effects were observed in the pair-feeding groups. The erythroblastic changes observed in this 4-day study were thought to reflect the direct influence of 5-FU administration. Since concerns regarding the influence of secondary changes related to undernutrition were minimized in the 4-day study, it was thought to clarify the direct influence of 5-FU administration on erythroblastic cells. Thus, a 4-day study protocol might be helpful for distinguishing secondary changes related to undernutrition.     

Evaluation of myelotoxicity in dietary restricted rats

The purpose of this study was to clarify the effect of decreased food consumption on evaluation of myelotoxicity in routine general toxicity studies. Male rats were divided into the following 7 groups: 12, 15, and 18 mg/kg 5-fluorouracil (5-FU) treatment groups (FU12, FU15 and FU18); dietary restriction groups (R12, R15 and R18 receiving the same amount of food as the rats in the FU12, FU15 and FU18 groups, respectively); and a nontreated control group (NT). We compared the changes in body weight, hematology and the results of cytological analyses of bone marrow and histopathology among the groups after administration and recovery periods of 14 and 7 days, respectively. At the end of the administration period, the FU15 and FU18 groups showed decreases in many hematologic and bone marrow parameters that were all similar to those in the corresponding dietary restriction groups (R15 and R18). A granulocyte abnormality (polyploidy: frequency of 1% or less) was also observed in all 5-FU treated groups. At the end of the recovery period, increases in the reticulocyte and platelet counts and extramedullary hematopoiesis of the spleen were observed in the 5-FU treated groups. These results indicate that the results of general toxicity studies in rats should be evaluated in consideration of dietary restriction effects when food consumption is decreased at about 30-40% or more. Careful morphological observation of hemocytes would be helpful in distinguishing the effect of a drug from that of dietary restriction in relation to hematological and bone marrow parameters. Performance of a recovery test to determine the reactive response of hematopoiesis is also recommended.     

Cryptosporidium infection in a veal calf cohort in France: molecular characterization of species in a longitudinal study

ABSTRACT: Feces from 142 animals were collected on 15 farms in the region of Brittany, France. Each sample was directly collected from the rectum of the animal and identified with the ear tag number. Animals were sampled three times, at 5, 15 and 22 weeks of age. After DNA extraction from stool samples, nested PCR was performed to amplify partial 18S-rDNA and 60 kDa glycoprotein genes of Cryptosporidium. The parasite was detected on all farms. One hundred out of 142 calves (70.4%) were found to be parasitized by Cryptosporidium. Amplified fragments were sequenced for Cryptosporidium species identification and revealed the presence of C. parvum (43.8%), C. ryanae (28.5%), and C. bovis (27%). One animal was infected with Cryptosporidium ubiquitum. The prevalence of these species was related to the age of the animal. C. parvum caused 86.7% of Cryptosporidium infections in 5-week-old calves but only 1.7% in 15-week-old animals. The analysis of the results showed that animals could be infected successively by C. parvum, C. ryanae, and C. bovis for the study period. C. parvum gp60 genotyping identifies 6 IIa subtypes of which 74.5% were represented by IIaA15G2R1. This work confirms previous studies in other countries showing that zoonotic C. parvum is the dominant species seen in young calves.     

Prevalence of Salmonella antibodies among goats slaughtered for chevon in Bareilly (Northern India)

We screened serum samples of 1024 goats slaughtered for chevon in Bareilly in Northern India for Salmonella antibodies with indirect ELISA, MAT-H (microagglutination test using flagellar antigens e, n, x and 1, 5) and MAT-O (microagglutination test using somatic antigens 4, 12 and 3, 10, 15). Salmonella antibodies were detected in 48, 8 and 40%, goats using Salmonella-cytotoxi-I ELISA, MAT 'H' and MAT 'O', respectively. After adjusting for test accuracy, the seroprevalence were highest for Salmonella-cytotoxi-I ELISA (46%) followed by agglutinins against 'O' 3, 10, 15 (15%) and negligible for other agglutinins. With all 5 tests, prevalence of Salmonella antibodies was significantly higher in females than in males. No significant difference was evident in prevalence of Salmonella antibodies to different antigens in different age groups of male goats except for e, n, x agglutinins that were significantly more prevalent in young adult (<6-18 months) males than in adult (>18 months of age) or young (< or =6 months of age) goats. On the other hand, in females, prevalence of Salmonella-cytotoxin-I antibodies and e, n, x agglutinins differed significantly among three age groups, being the most prevalent in adult goats. As expected, the results of different tests had little or no correlation because the different tests targeted antibodies to different antigens.     

The effect of age of host in resistance expressed at the gut level in rats infected with Fasciola hepatica

The development of oral and intraperitoneal infections with Fasciola hepatica in young and old rats showed that the gut was involved in the expression of age resistance. The role of the gut was assessed by comparison of the number of flukes recovered 4 and 10 weeks after oral or intraperitoneal infection of 2-, 6-, 15-, and 35-week-old male Wistar rats and 6- and 15-week-old male DA rats with encysted metacarcariae of F. hepatica.Rats of both strains behaved similarly in their response to F. hepatica infection. For both routes of infection the number of flukes recovered decreased as host age increased. In 22- and 6-week-old rats equal numbers of flukes were recovered at 4 and 10 weeks after oral or intraperitoneal infection. In 15-week-old rats, fluke burdens 4 weeks after infection were significantly greater following intraperitoneal infection than oral infection. A significant loss of flukes from the intraperitoneal infection of 15-week-old Wistar rats occured between 4 and 10 weeks after infection. In 35-week-old Wistar rats there was no significant effect for route or age of infection.As intraperitoneal infection (to by-pass rejection at the gut level) only partially eliminates the age response, additional age related mechanism(s), able to reject flukes at some time after they have entered the peritoneal cavity, must be operative in the peritoneal cavity and/or the liver.     

Neurotoxicity induced by a single oral dose of aniline in rats.

The neurotoxicity of aniline and its age-dependent responses were investigated in male rats. Groups of 6 rats, 4-week-old, were treated once with aniline (500, 750 or 1,000 mg/kg) or olive oil by gavage. Additional groups of 6 rats, 7- or 10-week-old, were treated once with 800 mg/kg of aniline or olive oil. Paralytic gait or hindlimb paralysis was observed between post-treatment days 8 and 15 in two out of six rats receiving 1,000 mg/kg of aniline at 4 weeks of age. On post-treatment day 15, spongy change in the white matter of the spinal cord was observed in all rats receiving 750 or 1,000 mg/kg of aniline at 4 weeks of age. The lateral and ventral columns of the thoracic spinal cord were the most severely affected. Spongy change in the facial nerve and spinal trigeminal tracts of pons and medulla oblongata, and mild degeneration of the peripheral nerves was found in 3 out of 6 rats receiving 1,000 mg/kg of aniline. At the ultrastructural level, the spongy change was due to distention of the myelin sheath and splitting of the intraperiod line. Axons were well preserved in the affected nerve fibers. No abnormalities were seen in the neuronal cell bodies. Although transient cyanosis was observed in all rats receiving 800 mg/kg of aniline at 7- or 10-week-old, as well as in rats receiving 750 or 1,000 mg/kg of aniline at 4-week-old, no treatment-related neurobehavioral or morphologic abnormalities were found in the former. These findings demonstrate the neurotoxicity of orally administered aniline for rats, depending upon the age of the animal at the time of administration.     

A comparison between the efficacy of thiabendazole and febantel on experimental trichinellosis in rats

Febantel at a dose level of 5 mg kg-1 had a lethal efficacy of 54.1% against the adult worm and 69.5% against the migrating larvae of Trichinella spiralis in rats. When administered at 15 mg kg-1, it demonstrated lethal effects of 94.4, 92.5 and 74.7% against adult, young and encysted larvae, respectively. Infected rats treated with 300 mg kg-1 died. Thiabendazole had efficiencies of 96.4 and 83.3% against intestinal and migrating early muscle phases, respectively, and was 42% effective against the encysting phase.     

Pharmacokinetics, metabolism and renal clearance of flumequine in veal calves

The pharmacokinetics of flumequine was studied in 1-, 5- and 18-week-old veal calves. A two-compartment model was used to fit the plasma concentration-time curve of flumequine after the intravenous injection of 10 mg/kg of a 10% solution. The elimination half-life (t1/2 beta) of the drug ranged from 6 to 7 h. The Vd beta and ClB of 1-week-old calves (1.07 l/kg, 1.78 ml/min/kg) were significantly lower than those of 5-week-old (1.89 l/kg, 3.23 ml/min/kg) and 18-week-old calves (1.57 l/kg, 3.10 ml/min/kg). After the oral administration of 10 mg/kg of a 2% flumequine formulation mixed with milk replacer, the Cmax was highest in 1-week-old (9.27 micrograms/ml) and lowest in 18-week-old calves (4.47 micrograms/ml). The absorption was rapid (Tmax of approximately 3 h) and complete. When flumequine itself and a formulation containing 2% flumequine and 20 X 10(6) iu of colistin sulphate were mixed with milk replacer and administered at the same dose rate, absorption was incomplete and Cmax was lower. The main urinary metabolite of flumequine was the glucuronide conjugate (approximately 40% recovery within 48 h of intravenous injection) and the second most important metabolite was 7-hydroxy-flumequine (approximately 3% recovery within 12 h of intravenous injection). Only 3.2-6.5% was excreted in the urine unchanged. After oral administration a 'first-pass' effect was observed, with a significant increase in the excretion of conjugated drug. For 1-week-old calves it is recommended that the 2% formulation should be administered at a dose rate of 8 mg/kg every 24 h or 4 mg/kg every 12 h; for calves over 6 weeks old, the dose should be increased to 15 mg/kg every 24 h or 7.5 mg/kg every 12 h. The formulation containing colistin sulphate should be administered to 1-week-old calves at a flumequine dose of 12 mg/kg every 24 h or 6 mg/kg every 12 h.     

Experimental induction of chronic borreliosis in adult dogs exposed to Borrelia burgdorferi-infected ticks and treated with dexamethasone.

OBJECTIVE: To develop a method to experimentally induce Borrelia burgdorferi infection in young adult dogs. ANIMALS: 22 healthy Beagles. PROCEDURE: All dogs were verified to be free of borreliosis. Twenty 6-month-old dogs were exposed to Borrelia burgdorferi-infected adult ticks and treated with dexamethasone for 5 consecutive days. Two dogs not exposed to ticks were treated with dexamethasone and served as negative-control dogs. Clinical signs, results of microbial culture and polymerase chain reaction (PCR) testing, immunologic responses, and gross and histologic lesions were evaluated 9 months after tick exposure. RESULTS: Predominant clinical signs were episodic pyrexia and lameness in 12 of 20 dogs. Infection with B burgdorferi was detected in microbial cultures of skin biopsy specimens and various tissues obtained during necropsy in 19 of 20 dogs and in all 20 dogs by use of a PCR assay. All 20 exposed dogs seroconverted and developed chronic nonsuppurative arthritis. Three dogs also developed mild focal meningitis, 1 dog developed mild focal encephalitis, and 18 dogs developed perineuritis or rare neuritis. Control dogs were seronegative, had negative results for microbial culture and PCR testing, and did not develop lesions. CONCLUSIONS AND CLINICAL RELEVANCE: Use of this technique successfully induced borreliosis in young dogs. Dogs with experimentally induced borreliosis may be useful in evaluating vaccines, chemotherapeutic agents, and the pathogenesis of borreliosis-induced arthritis.     

A study on possibility of Rosa canina seed use as feed ?ngredient in diets of Morkaraman male lambs

This experiment was carried out to evaluate the ground Rosa canina seed at various levels (0%, 5%, and 15%) in barley-soybean-based concentrates offered to Morkaraman male lambs at approximately 8?months of age, on fattening performance, carcass, and meat quality characteristics. The lambs were divided into three treatment groups including R1 (concentrate without R. canina seed; n?=?12), R2 (concentrate with 5% R. canina seed; n?=?12), and R3 (concentrate with 15% R. canina seed; n?=?12) at the beginning of fattening period. The soybean meal was used as main protein source in treatment groups. All of the groups were fed a diet consisting of concentrate offered ad libitum and 300?g of grass hay per lamb per day during 60-day fattening period. The effect of diet on daily weight gain was found statistically significant. The control group had higher daily weight gain than R3 groups with 15% of ground R. canina seed. The hot carcass and cold carcass weights and dressing percentage values were affected by diets, and R3 group fed concentrate with 15% R. canina seed had higher carcass weights and dressing percentages than R1 and R2 groups. Differences among the groups in terms of leg, rib, and hindshank weights were found highly significant. While R1 and R2 groups were not significantly different, R3 group was significantly higher to R1 and R2 groups in leg, rib, and hindshank weights. In addition, meat color parameters and pH values were not affected by diets in present study.     

Immunohistochemical localisation of rabbit haemorrhagic disease virus VP-60 antigen in early infection of young and adult rabbits

This study evaluated the time course distribution of rabbit haemorrhagic disease virus (RHDV) structural protein VP60 in tissues from experimentally infected rabbits from three different age groups. Viral VP60 antigen could not be detected in tissue samples from animals under four weeks, and only a few hepatocytes (0.01 to 0.2 per cent) were stained in the 6-week-old animals. A 6-week-old rabbit euthanised at 72 hpi showed VP60-labelling in hepatocytes and macrophages close to areas of inflammation. Viral VP60 antigen was detected as early as 12 hpi in a few hepatocytes (0.03 per cent) from adult animals. Within this age group, the extent of hepatocyte labelling considerably increased at 18 (3.0 per cent), 24 (25.5 per cent), 36 (50 per cent) and 48 (60 per cent) hpi. Extrahepatic viral VP60 antigen was also detected at 36 and 48 hpi in spleen macrophages and lymphocytes from adult rabbits. These findings support the hypothesis that the hepatocyte is the only cell type in the liver able to support RHDV replication almost immediately after viral infection.     

Effect of decoquinate on the control of coccidiosis in young ruminating calves

Twenty-five 6-week-old Holstein male calves were each inoculated with 500,000 sporulated oocysts of Eimeria bovis. Two nontreated (control) and 3 treated calves (1.5 mg of decoquinate/kg of body weight in feed) were necropsied 7 days after inoculation. Similar groups of calves were necropsied at 12, 18, 22, and 28 days after inoculation. Treated calves were started on medicated feed 2 days before inoculation or at 7, 12, or 15 days after inoculation or were on continuous medication from the day of inoculation. Control calves were not given medication. Early schizonts were in the small intestines of control calves at 7 days after inoculation, but none was in the treated calves that were started on medicated feed 2 days before inoculation. Schizonts were present in the small intestine of both treated and control calves at 12 days after inoculation. At 18 days after inoculation, control calves had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestines, but treated calves only had schizonts in the small intestine. At 22 days, control calves had schizonts in the small intestine and gamonts and oocysts in the large intestine; treated calves had schizonts in the small intestine. At 28 days, controls still had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestine; the treated calves that had been on continuous medication did not have schizonts, gamonts, or oocysts in the tissues. Decoquinate apparently kills sporozoites or arrests development and release of merozoites from the schizonts when fed at 1.5 mg/kg of body weight in the feed.     

Prophylaxis using paromomycin of natural cryptosporidial infection in neonatal kids

The chemoprophylactic effects of paromomycin sulfate against natural cryptosporidiosis in young kids were investigated. Two studies were carried out using two groups of 18 and 12 animals in two pens. In each pen, kids were allocated to treated or control groups. The treatment consisted of oral paromomycin given at 100 mg kg⁻¹ body weight day⁻¹ for 11 consecutive days from 2 days of age. All kids were weighed at 2, 6 and 10 days of age. Infection was monitored by collecting fecal samples and staining fecal smears every 3–4 days from days 4 or 5 to days 15 or 19. The results clearly showed the efficacy of paromomycin in reducing cryptosporidial oocyst output. Moreover, paromomycin prevented clinical signs and mortality.     

Factors affecting premature chromosome condensation of cumulus cell nuclei injected into rat oocytes

To date, production of cloned rats by somatic cell nuclear transfer (NT) has not yet been successful. Inducing premature chromosome condensation (PCC) of injected cell nuclei in recipient cytoplasm is considered essential for successful mouse cloning by the Honolulu method. In the present study, some factors affecting PCC of rat cumulus cell nuclei injected into rat oocytes were examined. Wistar female rats (young: 4 to 5-week-old, mature: > or =10-week-old) were superovulated by injections of eCG and hCG, and oocytes recovered 14 or 17 h after hCG injection were received with cumulus cell nuclei using piezo-driven micromanipulator. When the oocytes were recovered 14 h post-hCG injection from young rats and the nuclear injection into oocytes was completed within 45 min, PCC was observed in 44-49% of NT oocytes. In the case of oocytes from mature rats, PCC occurred in 11-19% of the NT oocytes. Oocytes recovered 17 h post-hCG injection did not support PCC of the injected nuclei (0-7%) regardless of the donor age. Treatment of oocytes with a neutral cysteine protease inhibitor, N-acetylleucylleucylnorleucinal, slightly increased the incidence of PCC (48 vs 37%). Comparison of rat strains for oocyte donors indicated that proportions of NT oocytes undergoing PCC in Wistar and LEW oocytes (41-46%) were higher than those in Donryu and F344 oocytes (17-25%). Thus, ability of rat oocytes to promote PCC of the injected nuclei is dependent on the characteristics of oocytes, such as age or strain of donor rats, and timing of oocyte recovery.     

Safety evaluation of moxidectin sustained-release injectable in 10-week-old puppies

A study was conducted to evaluate the safety of a commercial formulation of moxidectin sustained-release injectable for dogs (ProHeart 6, Fort Dodge Animal Health) administered as a single subcutaneous dose to 10-week-old puppies. Twelve male and 12 female purpose-bred beagles 10 weeks of age were blocked by weight within gender and randomly allocated to three treatment groups. Puppies in two groups were treated with moxidectin sustained-release injectable for dogs at three or five times the labeled dose rate of 0.17 mg moxidectin/kg. The third group was treated with saline solution as controls. Physical and neurologic status, hematologic parameters, clinical chemistries, urine samples, body weight, and food consumption were evaluated before and up to 12 weeks after treatment. When compared to controls, mild depression of erythropoiesis, characterized by reduced hemoglobin, reticulocytes, erythrocytes, and hematocrit, was noted in puppies treated with five times the label dose of moxidectin sustained-release injectable. Values for these parameters remained within normal ranges and increased during the study, but at a reduced rate relative to saline-treated controls. Other parameters evaluated remained within normal limits for all treatment groups. Based on results of this study, the no observed adverse effect level for moxidectin sustained-release injectable (ProHeart 6) treatment in 10-week-old puppies was determined to be three times the recommended rate.     

Effects of live attenuated and killed Salmonella vaccine on T-lymphocyte mediated immunity in laying hens

The impact of live and killed Salmonella vaccines on cell-mediated immunity (CMI) was investigated in 18- and 32-week-old White Leghorn chickens, by assessing splenic lymphocyte proliferation, expression of IL-2 mRNA in concanavalin A (Con A) stimulated cells and flow cytometric analysis of cell subpopulations. Con A and Salmonella enteritidis (SE) flagella induced proliferation of splenocytes were enhanced in the 18- and 32-week-old chickens treated with live vaccine, compared to the corresponding control chickens. Among the killed vaccine treated birds, Con A-mediated response was higher in the 18-week-old chickens compared to the corresponding control birds. Increased proliferation was accompanied by increased CD4 and reduced CD8 and gammadelta T-lymphocytes in the 18-week-old live vaccine treated chickens. Relative expression of IL-2 mRNA in Con A-stimulated splenocytes from 18-week-old birds was not affected by vaccine treatment. Overall, live vaccine was more effective in increasing the lymphocyte proliferation to Con A as well as SE antigen. This enhanced CMI may prove beneficial in protecting chickens against SE infection.     

VIPR-1基因5′调控区多态位点与鸡就巢性的关联分析

本研究旨在探索血管活性肠肽I型受体(Vasoacitve intestinal peptide type I receptor,VIPR-1)基因5′调控区(-496～-1bp)多态性及其单倍型效应对鸡就巢性的影响,寻找影响肉鸡就巢性的分子标记,为降低或者剔除肉鸡就巢行为的育种研究提供相应依据。采用测序技术对498只清远麻鸡VIPR-1基因5′调控区进行多态性检测及基因型分析,利用最小二乘均数对VIPR-1基因5′调控区的多态位点与就巢性状进行相关分析,利用PHASE软件对多态位点进行单倍型分析。结果,VIPR-1基因5′调控区存在12个多态性位点,G-359T、G-266T、A-134G、A-94G、C-72G对18～43周龄的就巢持续天数影响达到显著水平(P<0.05),A-94G位点对18～54周龄的就巢率的影响达到显著水平(P<0.05);构建的单倍型对18～54周龄的就巢持续天数的影响达到极显著水平(P<0.01)。最小二乘分析结果表明,CCTGGGAAGCAG/TTGGGGAAGCAC型个体的就巢持续天数比其它单倍型个体极显著的延长(P<0.01)。结果表明,VIPR-1基因5′调控区(-496～-1bp)可能存在影响鸡就巢行为的分子标记,CCTGGGAAGCAG/TTGGGGAAGCAC型个体对鸡就巢性具有较大的遗传效应,可作为分子标记应用于家鸡就巢行为的筛选。     

Age-dependent pharmacokinetics of oxytetracycline in ruminants

Oxytetracycline (OTC) was administered intravenously (i.v.) to 3-and 12-week-old calves and lactating cows, and both i.v. and intramuscularly (i.m) to 14-week-old calves and non-lactating cows. Concentrations of OTC were determined in plasma and were analysed kinetically. The pharmacokinetic parameters which were derived using the three-compartment open model were inadequate to describe plasma drug levels in six out of the 23 animals treated i.v., and, therefore, model-independent kinetic parameters were utilized for evaluating age-dependent pharmacokinetics of OTC. In the 3-week-old calves, the total body clearance (Cl b ) was 0.0022 ml/min/kg, the total distribution volume (V d area ) was 2.48 l/kg, and the distribution volume of the central compartment (V 1 ) was 0.56 l/kg. Mean values for Cl b , V d area , and V 1 in 3-week-old calves were two-, three- and four-fold greater, respectively, than the corresponding values in cows. Mean values of Cl b and V d area for the 12-and 14-week-old calves were intermediate between the corresponding values in 3-week-old calves and cows. Dose and state of lactation did not affect the model-independent parameters. The i.v. and i.m. data illustrated that the recommended dose levels of OTC in young calves should be twice those employed in cows for obtaining similar plasma OTC concentration-time profiles.     

Fertility control of Rattus nitidus using quinestrol: effects on reproductive organs and social behavior

Fertility control has been identified by studies in the laboratory and the field as a more appropriate and long‐term control strategy for rodent pests than lethal control. In this study, we investigated the effects of quinestrol on mass of reproductive organs and on social behaviors in female and male Himalayan field rats (Rattus nitidus). A total of 16 adult females and 16 adult males were randomly assigned to 4 groups. One male and one female group were fed rice with 0.005% quinestrol by weight for 7 days, and another 2 groups were fed rice only. After 7 days, rats were assigned to 10 min dyadic encounters between groups, and investigation, aggression, defense and attack latency were quantified. All animals were killed on day 10, and reproductive organs were dissected and weighed. Dyadic encounter data showed that there were obvious changes in social behaviors of quinestrol‐treated rats. Quinestrol significantly inhibited the investigative behavior of quinestrol‐treated males toward control females in Rattus nitidus, but seldom affected investigation between control males and quinestrol‐treated females. Aggression of control females toward quinestrol‐treated males was higher than that of quinestrol‐treated females, and defense of quinestrol‐treated males toward control females was more remarkable than that of control males. Quinestrol remarkably decreased wet masses of epididymis and spermotophore in males and ovaries in females, but had no effect on wet masses of testes and uteri after quinestrol treatment. These results indicate that the anti‐fertility effects of quinestrol on R. nitidus are attributed to not only suppressing reproductive organs but also impacting social behaviors associated with territory defense and mate choice.     

Ascaridia galli infections in free-range layers fed on diets with different protein contents

1. One hundred and twenty 17-week-old Lohman Brown hens were divided into 4 groups. Groups 1 and 3 were given a diet with 180 g protein/kg and groups 2 and 4 were given a diet with 140 g protein/kg. Groups 1 and 2 were orally infected with 500 (50) embryonated Ascaridia galli eggs. 2. Marked differences in mean weekly weight gain for the 4 groups were observed. 3. Hens given 140 g protein/kg had a significant lower mean worm burden of adult A. galli worms and a significant lower weight gain compared to the group given 18 g protein/kg. 4. There was no significant difference in faecal egg counts between the 2 parasitised groups. 5. The egg production did not differ significantly between any of the groups. 6. The results of this study indicate that the amount of dietary protein in the diet has an effect on the establishment of A. galli infections in the gut of layers kept under free range conditions.