Higher Egg Output Research Articles

Studies on the Comparative Effect of Organic and Synthetic Feed on the Growth and Serum Metabolites of Broiler Chicks

Introduction: Modern broiler production efficiency is built on the improved feed for high growth and egg output. Growth performance of broilers greatly influenced by the feed contents. Objective: The objective of this study was to analyze the impact of organic and synthetic feed on the growth, feed utilization and serum metabolites of broilers chicken. Material and Methods: This experiment was conducted for 28 days on broiler chickens. Broilers were divided into five treatments such as T0, T1, T2, T3 and T4. Control group T0 received basal diet. T1 and T2 received organic feed. T3 and T4 received synthetic feed. Results: All the feed were given at the levels of 3% and 6%. Feed were given orally in the form of pellets. Practical implication: Growth performance were observed and recorded at weekly basis. After the completion of trial, blood sample were taken for the analysis of serum metabolites. Conclusion: Results showed that value of WG, absolute weight gain and SGR were increased significantly (p<0.05) in combine treatment T2 (6% organic feed) with respect to T0 (control group). Feed intake and FCR was significantly (p<0.05) in treatment T2. Serum metabolites i.e. cholesterol, triglycerides, glucose and total protein were significantly analyzed (p<0.05).The result of present study explained that T2 having organic feed showed better growth performance of broiler chickens. Keywords: broilers chicken, feed requirement, weight gain, FCR, serum metabolites,

The efficacy of a single oral dose of albendazole against soil-transmitted helminthiasis in Ogun State, Nigeria

Soil Transmitted Helminths (STHs) are Neglected Tropical Diseases of global public health importance. This study evaluated the efficacy of albendazole (ALB) amongst primary school children aged 6 – 16 years in STH-endemic communities in Ogun State, Nigeria. Demographic characteristics were obtained and stool samples were collected and analysed by Kato-Katz at baseline and 15 and 21 days post-treatment. All study participants were treated with a single ALB 400 mg tablet. A total of 282 participants were screened at baseline, of which 151 were found to be excreting STH (51.4%) of which A. lumbricoides was the most prevalent STH (n = 137, 48.6%), followed by hookworm (n = 60 children, 21.3%) and T. trichiura (n = 3; 1.1%). The prevalence across the four schools varied from 31.3% to 73.9% for A. lumbricoides, from 6.8% to 56.3% for hookworm, and from 0.0% and 2.2% for T. trichiura infections. Of the 151 children excreting any STH infection at baseline, 131 (86.8%) provided a stool sample 15 and 21 days after treatment. The mean fecal egg counts across these complete cases at baseline was 5,096 (± 13,735) eggs per gram (EPG) for A. lumbricoides, 2,202 (±7,849) for hookworms and 288 (±375) for T. trichiura. Fifteen days after drug administration the therapeutic efficacy, measured as the reduction in mean fecal egg count (FEC) following drug administration (ERR), was 99.7% (95CI: 99.4-99.9) for A. lumbricoides and 69.2% (95CI: 28.7-92.8) for hookworms. The hookworm ERR at day 14 was reduced due to the continued high egg output of one highly infected individual. One week later, 21 days following drug administration, ERR for hookworm also reached satisfactory levels (99.4% (95CI: 98.7-99.8)). This study highlights that ALB still shows satisfactory efficacy to Ascaris and hookworm infections in Ogun State, Nigeria.

Correlation Analysis between MyoG Gene Polymorphism and Carcass Characteristics of Egg quails

Quail is extensively reared in China for characteristic of quick growth, small fodder consumption, early sexual maturity, high egg output and short production period. In this study, the SNP markers in 5’ regulation regions of cytogenin gene (MyoG) among China yellow quail, Beijing white quail and Korean quail were detected by PCR-SSCP method. Moreover, correlations of MyoG 5’ regulation regions with carcass characteristics of quail were analyzed. Results demonstrated thatin egg quail group, six genotypes were detected in Locus A in the control region of MyoG 5’, including AA, BB, CC, AB, AC and BC. The highest frequencies of CC in China yellow quail, Beijing white quail and Korean quail were 0.323, 0.366 and 0.444, respectively. A total of 9 genotypes were detected in locus B in egg quail group, which were AA, BB, CC, DD, EE, AB, AC, AD and AE. AA showed the highest frequency in China yellow quail, Beijing white quail and Korean quail, which were 0.493, 0.385 and 0.406, respectively. There was significant correlation between locus A and leg muscle rate of egg quail (plessthan0.05). Locus B presented significant correlations with carcass net weight, leg muscle weight, dressing percentage, whole net carcass rate and heart rate (plessthan0.05). Loci A and B in the control region of MyoG 5’ can be used as the molecular marker of carcass characteristics of egg quails during marker assisted selection.

Modeling adult emergence and fecundity of factitious hosts under different food sources supports massive egg production management.

Ephestia kuehniella (Lepidoptera, Pyralidae) and Sitotroga cerealella (Lepidoptera, Gelechiidae) are important factitious hosts used for production of biological control agents. Their differences in terms of biology and behavior require adjustments in their mass production, particularly when using corn or barley as food in grain or in bran. We modeled adult emergence, oviposition period and egg production along time after emergence, as a function of the food source. Significant differences between hosts or food type were found for these variables and for adult weight but not for sex ratio. Our results confirm the possibility of mass production of these hosts using corn or barley as food source. Integrating adult emergence patterns and age specific fecundity patterns into a single model, it is clear that rearing E. kuehniella on barley would result in the highest egg output in much shorter time than E. kuehniella on corn or S. cerealella on barley.

Treatment with nitric oxide donors diminishes hyperinfection by Strongyloides venezuelensis in mice treated with dexamethasone

The effects of using nitric oxide (NO) donors and inhibitors in experimental strongyloidiasis were showed using, both naïve and dexamethasone immunosuppressed BALB/c mice infected with Strongyloides venezuelensis. Aminoguanidine, an inhibitor of inducible NO synthase and LA419 a NO donor, were administered. Dexamethasone was used to induce immunosuppression. The study in BALB/c mice revealed increases in counts of fecal eggs, larvae in lungs and parasitic females following treatment with aminoguanidine, while mice treated with LA419 had limited egg output with low larval and adult recoveries. Mice immunosuppressed with dexamethasone developed hyperinfection with high long lasting fecal egg emission, high numbers of larvae in lungs and high numbers of parasitic females in the intestine even when the infection had already been cleared in non-immunosuppressed infected controls. Mice treated with dexamethasone and aminoguanidine had the highest egg output and the highest larva and parasitic female recovery showing a severe hyperinfection syndrome. In contrast, treatment with dexamenthasone and LA419 resulted in a controlled hyperinfection syndrome and these mice were able to eliminate the parasite. Therefore, NO modulation appears to be a determinant factor in severe strongyloidiasis and further studies should be conducted to confirm in other experimental models.

Impact of Schistosoma mansoni on malaria transmission in Sub-Saharan Africa.

BackgroundSub-Saharan Africa harbors the majority of the global burden of malaria and schistosomiasis infections. The co-endemicity of these two tropical diseases has prompted investigation into the mechanisms of coinfection, particularly the competing immunological responses associated with each disease. Epidemiological studies have shown that infection with Schistosoma mansoni is associated with a greater malaria incidence among school-age children.MethodologyWe developed a co-epidemic model of malaria and S. mansoni transmission dynamics which takes into account key epidemiological interaction between the two diseases in terms of elevated malaria incidence among individuals with S. mansoni high egg output. The model was parameterized for S. mansoni high-risk endemic communities, using epidemiological and clinical data of the interaction between S. mansoni and malaria among children in sub-Saharan Africa. We evaluated the potential impact of the S. mansoni–malaria interaction and mass treatment of schistosomiasis on malaria prevalence in co-endemic communities.Principal FindingsOur results suggest that in the absence of mass drug administration of praziquantel, the interaction between S. mansoni and malaria may reduce the effectiveness of malaria treatment for curtailing malaria transmission, in S. mansoni high-risk endemic communities. However, when malaria treatment is used in combination with praziquantel, mass praziquantel administration may increase the effectiveness of malaria control intervention strategy for reducing malaria prevalence in malaria- S. mansoni co-endemic communities.Conclusions/SignificanceSchistosomiasis treatment and control programmes in regions where S. mansoni and malaria are highly prevalent may have indirect benefits on reducing malaria transmission as a result of disease interactions. In particular, mass praziquantel administration may not only have the direct benefit of reducing schistosomiasis infection, it may also reduce malaria transmission and disease burden.

Improving Access to Anti-Schistosome Treatment and Care in Nonendemic Areas of China: Lessons from One Case of Advanced Schistosomiasis Japonica

Schistosomiasis, caused by trematode blood flukes of the genus Schistosoma, is the second most prevalent disease after malaria in the tropical and subtropical world. Among five schistosome species, Schistosoma japonicum is the most serious, mainly because of its high egg output [1]. This parasite is mainly endemic in mainland China, the Philippines, and Indonesia. Advanced schistosomiasis, due to either an infection without chemotherapy or repeated infections over time, is the most serious form of schistosomiasis and is usually characterized by periportal liver fibrosis, spleen enlargement and congestion, portal hypertension, and other serious consequences [2]. The suffering for an advanced patient caused by schistosomes could last for a lifetime, as the associated pathological changes on the host, if not properly treated, could develop toward a more serious condition. In addition, S. japonicum in humans has been estimated to be able to live for an average of 4.5 years [3]. Prolonged survival of the parasite to as long as about 47 years has been seen in an American who emigrated from the Philippines and continued to show active eggs in rectal biopsies [4]. These eggs can continue to produce damages to organs where they are deposited. Therefore, the treatment of the disease usually includes both anti-schistosome treatment and symptomatic therapy. The former is based on fecal examinations and serological tests, which are usually negative in most cases [5], or endoscopic examination. The etiological treatment is comparatively easier when without any serious complication, and therefore, much more attention and financial aids are going to the latter. In the Zhejiang province of China for example, in 2003 there remained 1,187 advanced cases who still needed medical assistance, although the disease there had been interrupted a decade ago [6]. Such a looming problem has been suggested to exist for perhaps as long as another half century in China [7]. Fortunately, with the economic development and well-improved standards of living over the last decades in China, in 2004 the government of China redefined schistosomiasis control, together with the control of HIV/AIDS and tuberculosis, as one of its highest priorities in communicable disease control [8]. As one main part of the integrated control measures, the project for treatment of advanced schistosomiasis has been initiated across the endemic regions of China. Box 1 lists a series of regulations on that aspect made by the government. The main point of this is that a screening system for advanced schistosomiasis among local residents will be set up in each endemic county and, if a farmer is diagnosed with advanced schistosomiasis (see Box 2 for the diagnosis criteria), the involved medical expense will be mostly covered by different levels of government. Figure 1 shows the numbers of advanced cases and newly found cases in each province and, as the consequence of the project, the increasingly rising coverage rate of advanced cases [9]. The direct or long-term estimated benefit from this project, as estimated by the work [10], would be quite considerable. Here we presented a case observed in a nonendemic area within the Anhui Province of China to point out the demerit of the ongoing project and raise some aspects yet to improve. This follow-up investigation was approved by an ethics committee in both the Anhui Institute of Parasitic Diseases and Soochow University. A consent form was obtained from the patient, and she gave consent to have her case details published. Open in a separate window Figure 1 Numbers of advanced schistosomiasis japonica in China. (A) In each province by 2008; (B) in each province by 2003 and new cases found from 2004 to 2008; and (C) the coverage rates of the aid-project in the cases at the levels of nation or province (Anhui) over 2004 to 2008.

Modelling the faecal worm egg count curve during the periparturient period in Uruguayan Merino sheep

Disease caused by gastrointestinal nematodes (GIN) is one of the main constraints for sheep production worldwide. Although adult categories are more resistant to GIN, a temporary loss of acquired immunity is presented around parturition, which results in the so-called “periparturient rise” (PPR) in fecal excretion of GIN eggs. The objective of the present work was to study the dynamic of the PPR and to model the faecal worm egg count (FEC) curve during the periparturient period in Uruguayan Merino sheep. Faecal samples were collected from lambing ewes during 2009 and 2010 parturitions. FEC and infective larvae cultures of each sampling were recorded. A total of 2121 records from 748 ewes, the progeny of 107 sires, were used in the statistical analysis. FEC data were normalized using two logarithmic transformations: Log FEC= Loge (FEC+100) and Log FEC_st (Log FEC with the variance standardized within contemporary group). Three functions were compared to shape the PPR curve. Haemonchus spp. was the most prevalent parasite. Log FEC_st was the selected response variable of the model, for its better adjustment to a normal distribution and a more homogeneous residual variance. The fixed regression model with Legendre polynomials was the selected one, based on the selection model criteria (Akaike & Schwarz Bayesian Information Criteria). The highest egg output was observed between two and four weeks post-lambing. In conclusion, the PPR observed in Uruguayan Merino lambing ewes had the maximum egg output matched with the milk production peak.

Variability in measures of reproductive success in laboratory-kept colonies of zebrafish and implications for studies addressing population-level effects of environmental chemicals

Laboratory tests that quantify reproductive success using model fish species are used to investigate for population-level effects of endocrine disrupting chemicals (EDCs) and other chemicals discharged into the environment. Even for the zebrafish ( Danio rerio), however, one of the most widely used laboratory models, surprisingly little is known about the normal variability in measures of reproductive success and this information is crucial for robust test design. In this study, the dynamics of breeding and inherent variability in egg output/viability and sperm quality were characterized among individuals/colonies and over time in 34 colonies of laboratory-kept zebrafish over a 20-day study period. For this work, a ‘6 × 6’ (six males and six females) colony size was adopted, as this is both environmentally relevant and optimal when considering egg output and animal welfare combined: an initial experiment showed egg output per female increased with decreasing colony size however, there was also a parallel increase in aggressive behavior. Both egg output and viability in ‘6 × 6’ colonies were highly variable among colonies (with co-efficients of variation (CVs) of 30 and 11%, respectively) and over the 20-day study duration (considering egg output and viability of all the colonies combined, the CVs were 20 and 12%, respectively). The patterns of egg production also differed among the ‘6 × 6’ colonies, and they included a cyclical output, a consistent daily output, an infrequent egg output with intermittent days of very high egg output, and an output with no obvious pattern. Sperm quality, measured as percentage motility and curvilinear velocity (VCL), was variable both among individuals within ‘6 × 6’ colonies and across colonies, with percentage motility being the most variable parameter (mean CVs of 82% inter-individual within colonies and 49% inter-colony). Sperm quality did not, however, vary over a 24 h period. A minimum number of six replicate ‘6 × 6’ colonies, assessed daily for a period of 4 days, was required per treatment to detect a 40% change in egg output. The minimum numbers of individual males required per treatment to detect a 40% change in sperm quality using the breeding system adopted were 32 males for percentage motility and 12 males for VCL, equivalent to six and two ‘6 × 6’ colonies, respectively. These data demonstrate the need for high levels of replication when testing for effects of EDCs on reproductive output in the zebrafish model in an environmentally relevant (‘6 × 6’) breeding matrix.

DEVELOPMENT AND PATHOLOGY OF ECHINOSTOMA CAPRONI IN EXPERIMENTALLY INFECTED MICE

In the present article, several parasitological features of mice, each experimentally infected with 75 metacercariae of Echinostoma caproni (Trematoda: Echinostomatidae), were studied during the first 12 wk postinfection. Moreover, the early pathological responses also were analyzed and compared with data previously published on other host species of E. caproni to gain further insight into the factors determining worm rejection or establishment of chronic infections. The results obtained show that the pattern of E. caproni infection in mice is consistent with a highly compatible host-parasite system. This combination is characterized by a high worm establishment, high egg output, and long survival of the worms. However, some differences with respect to other highly compatible hosts have been observed, particularly in relation to the survival of the adult worms. Histological studies suggest that the kinetics of goblet cells, mucosal neutrophils, and mononuclear inflammatory cells in the mesentery seem to be essential in determining the course of E. caproni infection in mice.

The Benefit of Additional Oviposition Targets for a Polyphagous Butterfly

While the reasons for the prevalence of specialists over generalists among herbivorous insects have been at the focus of much interest, less effort has been put into understanding the polyphagous exceptions. Recent studies have suggested that these exceptions may be important for insect diversification, which calls for a better understanding of the potential factors that can lead to an increased host plant repertoire. Females of the Nymphalid butterfly, Polygonia c-album, were used to test if egg output and/or likelihood of finding a host increased with the addition of a secondary host. There was no effect of prior eggs on the host for willingness to oviposit on a plant. The main experiments were conducted both in small laboratory cages and in large outdoor experimental arenas. No positive effect was found when another oviposition target was added in small cages in the laboratory. On the other hand, in the outdoor arenas the females more often found a host to oviposit on and had a higher egg output when they had access to an additional host, even though the second host was lower in their preference hierarchy. The difference between these experiments was attributed to searching for acceptable host plants within a patch, a factor that was included in the large cages but not in the small. When host availability is limited, adding oviposition targets can potentially act to counterbalance specialization and thus favor the evolution of generalization.

Outcrossing hermaphroditic polychaete worms adjust their sex allocation to social conditions

Sex allocation theory predicts that simultaneous hermaphrodites shift sex allocation facultatively in response to variation in local group size. This study was performed to evaluate the relative investment in each sex function by the simultaneously hermaphroditic polychaete worm Ophryotrocha diadema and to test whether allocation to each sex depends on the number of reproductive competitors. Four experimental groups were set up (in a 2 x 2 factorial design) with small or large group size and with small or large enclosures to control for potential confounding effects of density. We measured the proportion of female and male investment in focal individuals. Results revealed that individuals regulated their reproductive output so that when reproductive competitors were present, the number of female gametes was strongly reduced and the male function increased. In contrast, under monogamy, individuals in small groups produced lower numbers of sperm but had a higher egg output than worms in large groups. Density did not affect sex allocation in our experiment. Our findings provide qualitative support for Local Mate Competition theory, but also show that the pattern of sex allocation specific to this species is more complex than expected by current theory.

Strongyloides venezuelensis infection susceptibility of seven inbred strains of mice

A trial was carried out to investigate the susceptibility of seven strains of mice to Strongyloides venezuelensis primary and secondary experimental infections, in order to provide the basis for genetic studies about resistance. Twelve six-week-old male inbred mice of the A/J, BALB/c, CBA/J, C3H/Hepos, C57BL/6, DBA/2 and NIH strains were infected s.c. with 2000 infective larvae. The mean worm counts (± SD) in the small intestine six days after infection were, in increasing order: 28 (± 19) in NIH; 647 (± 228) in BALB/c; 709 (± 425) in DBA/2; 731 (± 151) in C3H/Hepos, 801 (± 174) in CBA/J; 1024 (± 267) in C57BL/6 and 1313 (± 483) in A/J. C57BL/6 mice showed the highest fecal egg counts and NIH, the lowest. No eggs in fecal exams or nematodes in small intestines were recovered from animals reinfected 14 days after primary infection. NIH strain was highly resistant to primary infection by S. venezuelensis. The most susceptible of the other six strains appeared to be the C57BL/6 strain which presented a high nematode counting in intestine and the highest egg output.

The role of nutritional status and insulin-like growth factor in reduced physical growth in hepatosplenic Schistosoma mansoni infection

The influence of nutritional status and hormonal growth activity on the impaired somatic development of adolescents with the hepatosplenic clinical form of Schistosoma mansoni infection (HS), the intestinal form with high (IH) or low (IL) egg output and non-infected (NI) individuals was evaluated (in Comercinho, Minas Gerais State, Brazil, in 1996–1997) by measuring body mass index (BMI), insulin-like growth promoting factor (IGF-I) and its carrier protein (IGFBP-3). BMI, IGF-I and IGFBP-3 concentrations were significantly lower in the HS group compared with the IH and the NI groups, irrespective of age. BMI did not remain associated with the clinical form in the bi-variate model that included IGF-I and BMI or IGF-BP-3 and BMI, suggesting that in these groups IGF-I and IGFBP-3 levels were related to the clinical form but independent of nutritional status. It is suggested that physical growth impairment in hepatosplenic S. mansoni infection results from the synergistic action of both hepatic damage and nutritional restriction.

Fecundity and egg output by Toxocara canis in the red fox, Vulpes vulpes.

The role of the red fox Vulpes vulpes in the dissemination of eggs of Toxocara canis into the environment is considered with reference to female worm fecundity and egg output in the faeces of infected foxes collected from four localities in southern England. A significant positive correlation was found between female worm size and the number of eggs in the uterus but there was no significant relationship between T. canis worm numbers and egg output in fox faeces. Reliable estimates of worm burdens in foxes could not, therefore, be determined from faecal egg counts alone. The highest mean egg output of 2145.0 epg recorded from adult foxes indicated that fox cubs are not necessarily the main sources of environmental contamination with T. canis eggs. Saturated magnesium sulphate was found to be a more effective flotation solution than zinc sulphate and sodium chloride for recovering eggs from fox faecal samples.

Life-history strategies and population dynamics of abomasal nematodes in Svalbard reindeer (Rangifer tarandus platyrhynchus).

The observation that the total abundance of adult nematodes in the abomasum of Svalbard reindeer increases between October and April suggests adaptation to cope with the Arctic winter. Here we investigate the extent to which selection has led to similar life-history strategies in the 3 most numerous trichostrongyle species. The life-histories are found to differ markedly. We use flexible statistical models for the abundance and dispersion of parasites in the host population. One of the taxa, Marshallagia marshalli, was most abundant and had its highest egg output in the winter. In contrast, the abundance of the most common taxa, Ostertagia gruehneri, m. gruehneri was stable or declined from autumn to late winter, and the closely related taxa, O. gruehneri, m. arcticus, showed a similar over winter drop. The faecal egg output of these 2 taxa was highest in summer, as found in temperate trichostrongyle species. Despite the apparent contamination of summer pastures with O. gruehneri, calves showed negligible burdens until their second summer and the abundance of infection reached an asymptote within their third year. In contrast, the abundance of M. marshalli in calves showed a rapid increase over the first summer and by late winter was similar to peak levels found in adults (8000 worms). This increase could not be accounted for by the developing abomasum larvae population and is therefore evidence for transmission over the winter for this taxa. While M. marshalli showed little between-year variation, O. gruehneri showed 2-fold fluctuation in the abundance of infection. O. gruehneri may therefore play a role in the fluctuating population dynamics of the host. Since there was no apparent decline in abundance with host age in any of the 3 taxa there was no evidence of reindeer mounting an immune response.

Phase Feeding for Laying Hens: Effect of Protein and Essential Amino Acids on Egg Quality and Production

The effect on egg quality of reducing the dietary protein and methionine+cystine (experiment 1) and methionine+cystine, lysine and protein (experiment 2) for laying hens with increasing age was studied. In experiment 1, four groups of laying hens were fed different diets in one to three feeding-phases as follows, with protein and methionine+cystine, respectively, in g/10 MJ ME. Group A: 146 and 6.6 at 20-35 weeks (LP1), 136 and 6.0 at 36-74 weeks (LP2). Group B: 156 and 6.6 at 20-35 weeks (K1), 148 and 6.0 at 36-45 weeks (K2), 121 and 4.8 at 46-74 weeks (LP3). Group C: K1 at 20-35 weeks, K2 at 36-74 weeks. Group D: LP1 at 20-74 weeks. In experiment 2, two hen lines (Lohmann Brown and ISA Brown) were fed diets with the following contents of methionine+cystine, lysine and protein, respectively, in g/10 MJ ME. Group A: 4.5, 5.3 and 120 at 21-71 weeks (N). Group B: 5.0, 5.8 and 132 at 21-35 weeks (N10), N at 36-71 weeks. Group C: 5.4, 6.4 and 144 at 21-35 weeks (N20), N10 at 36-45 weeks, N at 46-71 weeks. Group D: 5.9, 6.9 and 156 at 21-35 weeks (N30), N20 at 36-45 weeks, N10 at 46-71 weeks. Egg production and feed intake were registered, and the diets were analysed for nutritional composition. Eggs were collected in each phase for each group for quality analysis, including egg weight, shell weight, shell percentage, albumen height, Haugh unit and shell colour. In experiment 1, no differences in production traits between the groups were observed. In phase 3, group B had an overall lower egg weight, but increased albumen height. In experiment 2, group D had the highest egg output. The egg weight increased and shell percentage and albumen quality decreased with increasing dietary amino acid and protein content, a situation which was especially evident in the first phase at 21-35 weeks of age.

Ability of Commercial Laying Hens Producing Different Egg Outputs to Meet Their Methionine and Energy Requirements When Fed the Same Diet

An experiment was conducted to determine whether commercial laying hens with different egg outputs could meet their Met requirement when fed the same diet. Three groups of hens were selected with either low, medium, and high egg output. Body weight of hens was positively related to egg output. As egg output increased, feed consumption increased. This resulted in essentially the same amount of energy consumed per gram of egg content (EC) for all three groups. Egg weight was greatest with hens producing the greatest EC. The Met intake of hens was increased with increased EC; however, the Met per gram of EC was not different for the three groups of hens. These data indicate that the Met and energy requirements of commercial layers can be met with one feed when individual hens produce different amounts of EC.

Worm population characteristics and pathological changes in lambs after a single or trickle infection with Teladorsagia circumcincta

The regulation of the worm population and of its pathological effects was studied after a single or trickle infection with T. circumcincta. One hundred and twenty lambs, 60 Romanov and 60 Merinos d'Arles, 3 months old, were distributed in four balanced groups: non-infected (G0), infected with 7000 L3 per animal once and slaughtered after 4 weeks (G14) or 8 weeks (G18), and infected 8 times and slaughtered after 8 weeks (G88). Parasitological, histological, haematological parameters and weight gains were recorded on each animal. Female and artificially nursed lambs had lower worm burdens and egg counts (epg) than males and naturally suckled lambs. No difference in parasitological parameters was seen between the two breeds, but Mérinos lambs infected once, had a higher increase in pepsinogen concentrations than Romanov lambs. In the infected animals, a significant proliferation of mast and eosinophil cells was observed in the abomasum wall. Serum pepsinogen concentrations were significantly higher 3 weeks p.i. and the weight gain was depressed during the first month p.i. The worm population was more numerous and younger in group G14 compared with G18 in which 24% of the worms had been expelled during the second month p.i. The female worms in G18 were longer and had more eggs in utero and higher egg output. After the trickle infection (G88) the take was reduced, female worms were longer with more eggs in vagina (pars ejectrix) and there was a higher variability in the number of eggs (compared with G18 data). The pepsinogen rise was smaller but no specific effect was seen on histological and haematological parameters. Repeatability values around 0.5 were estimated between 4 consecutive days of egg counts. However the correlations between epg 1 and 2 months p.i. or between pepsinogen concentration and parasitological parameters were not significant.

Epidemiological study of parasite infection in a cow-calf beef herd in Quebec

The patterns of gastrointestinal and pulmonary nematode infections in a previously untreated Aberdeen Angus cow-calf herd were observed between May 1988 and December 1990. The cow-calf herd and replacement heifers on separate pastures. The relatively high mean faecal egg counts of cows and heifers at the time of turnout were mainly owing to the maturation of hypobiotic worms. The strongyle egg counts of calves began to rise soon after turnout onto pasture and reached peak levels at the end of the grazing season. The number of infective larvae on pasture was highest during September/October. Ostertagia, Cooperia and Nematodirus were the most prevalent genera found at necropsy and on pasture. Larvae of these nematodes were able to overwinter on pasture and Ostertagia larvae, additionally, were able to overwinter in the host as arrested early fourth stage larvae. The high egg output of cows at the time of turnout may serve as a source of infection for their calves and be responsible for the late-season rise in pasture larval counts.