Improving feed efficiency of dairy cows through breeding is expected to reduce enteric methane production per unit of milk produced. This study examined the effect of 2 forage-to-concentrate ratios ...on methane production, rumen fermentation, and nutrient digestibility in Holstein and Jersey dairy cows divergent in residual feed intake (RFI). Before experimental onset, RFI was estimated using a random regression model on phenotypic herd data. Ten lactating Holstein and 10 lactating Jersey cows were extracted from the herd and allocated to a high or low pre-experimental RFI group of 5 animals each within breed. Cows were fed ad libitum with total mixed rations either low (LC) or high (HC) in concentrates during 3 periods in a crossover design with a back-cross and staggered approach. Forage-to-concentrate ratio was 68:32 for LC and 39:61 for HC. Cows adapted to the diets in 12 to 24 d and feces were subsequently collected on 2 d. Afterward, gas exchange was measured in respiration chambers and rumen liquid was collected once after cows exited the chambers. Pre-experimental RFI was included in the statistical analysis as a class (low and high RFI) or continuous variable. Methane per kilogram of dry matter intake (DMI) was lower for Holsteins than Jerseys and the response to increased concentrate level was more pronounced for Holsteins than Jerseys (27.2 vs.13.8%); a similar pattern was found for the acetate:propionate ratio. However, methane production per kilogram of energy-corrected milk (ECM) was unaffected by breed. Further, total-tract digestibility of neutral detergent fiber was higher for Jerseys than Holsteins. For RFI as a class variable, DMI, methane production regardless of the expression, and digestibility were unaffected by RFI. For RFI as a continuous variable, DMI was lower and methane per kilogram of DMI was higher for cows with negative (efficient) than positive (inefficient) RFI values, and neutral detergent fiber digestibility was higher for Holsteins with negative than positive RFI values, but not for Jerseys. Daily methane production and methane per kilogram of ECM were unaffected by RFI. In conclusion, methane per kilogram of DMI of Jerseys was lowered to a smaller extent in response to the HC diet than of Holsteins. When pre-experimental RFI was used as a continuous variable, higher methane per kilogram of DMI was found for cows with negative RFI than positive RFI values, but not for methane per kilogram of ECM. These findings call for validation in larger studies.
This revision of the original poultry guidelines has been prepared to assist in the planning, conduct and interpretation of studies designed to assess the anthelmintic efficacy of drugs (newly ...discovered or currently used) against helminth parasites of chickens and turkeys. The original set of poultry guidelines was published in 2003. The current version provides an update on procedures to study and quantify the most important helminth parasites of chickens and turkeys, and to integrate these poultry guidelines with a new series of general, reflective and host-specific guidelines relative to assessing anthelmintic efficacy in production and companion animals. General considerations required for the conduct of studies designed to evaluate anthelmintics regardless of animal host such as the selection of study animals, animal housing, feeding, study design, record keeping and statistical analysis are for the most part provided in the newly published general guidelines. Taken together, the general and poultry guidelines should help investigators and others design and conduct studies and evaluate data concerned with determining the efficacy and safety of anthelmintics in chickens and turkeys. Additionally, this revision draws attention to several timely considerations inherent to anthelmintic evaluations such as the need to properly collect helminth specimens for subsequent determinations (e.g. species and stage verification, helminth genotyping). The investigations addressed herein, will most likely provide the very first public record of a new product’s abilities to effectively reduce targeted, helminth infections in animals, and particular attention should be focused on study excellence and accuracy. Due to changes in consumer preferences, and new regulatory requirements, poultry husbandry, especially regarding laying hens, has changed immensely in many countries since the publication of the first poultry guidelines. These changes have generally allowed for a much greater exposure of birds to the source of helminth challenge (litter and fields as opposed to cages). Parasitic helminthiosis of poultry has therefore greatly increased in incidence and magnitude; changes that accentuate the need for more effective anthelmintic intervention and an update on the means of determining anthelmintic efficacy.
•Targeted treatment strategy improved feed conversion ratio.•Targeted treatment strategy improved egg production per hen per week.•Hens in the targeted treatment flocks had higher cumulative plumage ...scores.
Worm control is an important aspect of the successful management of the egg production industry. Of particular concern is Ascaridia galli, which at high parasite loads affect health and production in layers. Application of a targeted treatment strategy (TT) to control A. galli has shown promise. The purpose of this study was to explore the effect of such a strategy on welfare indicators and production performance of layers. Six flocks (F1–6) on a commercial farm were allocated to three treatment groups. Flocks F1 and F4 were treated (TT) with fenbendazole at 22, 27 and 36 weeks post-placement (WPP). Flocks F2 and F5 were treated at 27 WPP (conventional treatment, CT) and hens in flocks F3 and F6 served as untreated (UT) control groups. At 19, 35 and 45 WPP twenty-five hens plus thirty eggs per flock were randomly selected. Hens were weighed and their plumage conditions (PC) were assessed. The eggs were subjected to various external and interior quality analyses. Production data such as number of eggs/hen/week, egg mass and feed conversion ratio (FCR) were calculated from raw data obtained from all flocks on a weekly basis. The number of eggs/hen/week, egg mass and FCR were higher (P < 0.05) in the TT flocks and hens had better PC both at 35 and 45 WPP compared with other flocks. No differences in body weight and physical egg quality were observed between groups except for egg shell strength which was higher (P < 0.05) in the CT flocks. These data suggest that better production performance and plumage, which suggests improved health, can be achieved through the application of a TT strategy. The insights gained from this research should help to justify the extra cost and labor associated with the TT strategy.
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•No cross-reaction was observed between A. galli and H. gallinarum.•The lowest obtained frequency threshold for the detection of H. gallinarum was 0.8 %.•Significant correlation ...(R2=0.9) was found in the fractional abundance precision test.•ddPCR yielded a 6% higher detection rate compared to the flotation method.•Substantial agreement (Cohen’s k: 0.696) was found between the ddPCR and the flotation method.
Since the EU ban on battery cages, many studies have listed Ascaridia galli and Heterakis gallinarum as the most common roundworms in the European laying hen population. A complicating factor is that the eggs of these parasites are almost identical. Thus, lack of molecular diagnostic approaches has driven epidemiological studies to take on necropsy for species discrimination, which is labor and cost intensive. Here, we describe a novel diagnostic tool based on droplet digital PCR for simultaneous identification and absolute quantification of the eggs of both of these ascarids in chickens’ droppings using two different genus-specific primer-probe sets targeting the second internal transcribed spacer region (ITS-2) in the nuclear ribosomal (rRNA) gene array. No cross-reaction was observed when different combinations of DNA and species-specific primers and probes were tested. The lowest obtained frequency threshold for the detection of H. gallinarum in the presence of a constant A. galli DNA concentration was determined to be 0.8 %. After validation, we used the assay to analyze field samples collected from several Swedish laying hen farms. Out of 134 samples, 86 (64 %) were positive for A. galli while 11 (8.3 %) samples were positive for H. gallinarum. These samples were initially analyzed with flotation technique for detection of ascarid eggs. The results of the Cohen’s kappa indicated substantial agreement (85.8 %) between the two tests. In conclusion, we have validated a novel molecular-based diagnostic tool for quantification and differentiation between intestinal parasites of major importance in chickens with high precision. Although this study focuses on identification of parasites of laying hens, the findings may well have a bearing on all types of chicken production systems. The present study lays the groundwork for future research into epidemiology of these two important chicken parasite species.
Amphibians are among the most threatened vertebrate taxa due to anthropogenic habitat change and emerging pathogens. The fungus Batrachochytrium dendrobatidis (Bd) may cause trade‐offs between the ...immune responses and other important functions, such as mobility. The pool frog (Pelophylax lessonae) is red‐listed in Sweden, and an earlier study conducted in our study area did not detect the fungus. In this study, 67 Swedish pool frogs were tested for Bd. Of these, 28 adults were provided with external radio transmitters and tracked during the summer and autumn to compare movement among infected and non‐infected individuals. Additionally, we tested some individuals for Bd twice during the summer to study intra‐seasonal variation in individual infections. Our results suggest that Bd has recently invaded these pool frog populations. During autumn, movement distances of infected pool frogs were shorter compared to uninfected individuals, and summer movements within ponds were reduced by increasing Bd load. We also found that the frogs can clear (or reduce) Bd infection during their active season. The results from this study increase understanding of the implications of Bd infections in an anuran fringe population, as well as in amphibian metapopulations, and can further guide amphibian conservation planning and management.
A fringe population of Swedish pool frogs were screened for the chytrid fungus (Bd). Our results suggest that Bd has invaded the area during the last decade. Radio tracking of individuals indicated that movement distance is reduced in infected individuals. However, the pool frogs are able to clear infection.
Conventional and organic production systems mainly differ in feeding strategies, outdoor and pasture access, and the use of antibiotic treatments. These environmental differences could lead to a ...genotype by environment interaction (G × E) and a requirement for including G × E in breeding decisions. The objectives of this study were to estimate variance components and heritabilities for conventional and organic production systems and investigate G × E under these 2 production systems for female fertility traits in Danish Holsteins. The analyzed traits included the interval from calving to first insemination (ICF), the interval from first to last insemination, number of inseminations per conception (NINS), and non-return rate within 56 d after the first insemination. Records of female fertility in heifers and the first 3 lactations in cows as well as grass ratio of feed at herd level were collected during the period from 2011 to 2016. The performances of a trait in heifers and cows (lactation 1 to 3) were considered as different traits. The (co)variance components and the resulting heritabilities and genetic correlations were estimated using 2 models. One was a bivariate model treating performances of a trait under organic and conventional production systems as 2 different traits using a reduced data set, and the other was a reaction norm model with random regression on the production system and the grass ratio of feed using a full data set. The full data set comprised records of 37,836 females from 112 organic herds and 513,599 females from 1,224 conventional herds, whereas the reduced data set comprised records from all these 112 organic herds and 92,696 females from 185 convention herds extracted from the full data set with grass ratio of feed lower than 0.20. All female fertility performances of the organic production system were superior to those of the conventional production system. Besides, heterogeneities in additive genetic variances and heritabilities were observed between conventional and organic production systems for all traits. Furthermore, genetic correlations between these 2 production systems ranged from 0.607 to 1.000 estimated from bivariate models and from 0.848 to 0.999 estimated from reaction norm models. Statistically significant G × E were observed for NINS in heifers, non-return rate within 56 d after the first insemination in heifers, and ICF from the bivariate model, and for ICF and NINS in cows from the reaction norm model.
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•Application of the TT strategy significantly lowered the faecal egg counts of the flocks with A. galli.•Parasite worm burdens in the TT flocks remained low during egg production ...period.•Individual cloacal EPGs were low in the TT strategy.
The efficacy of a sustainable deworming strategy based on targeted treatments (TT) against Ascaridia galli was investigated for the first time in laying hen flocks on a Swedish commercial farm. Three experimental protocols with different levels of treatment, e.g. targeted treatment (TT), conventional treatment (CT) and untreated (UT), were tested in randomly allocated flocks of two different bird hybrids. Every second week faecal egg counts (FECs) were determined from pooled faecal materials collected on trays (20×27cm) placed for a maximum of 12h on the litter belts. In the TT, anthelmintic administration (fenbendazole, 1mg/kg body weight for 5days) started at 22 weeks post placement (wpp) and was repeated twice when the pooled FECs surpassed the assigned threshold of 200 egg per gram faeces (EPG). The CT flocks were treated once at 27wpp using the same anthelmintic. Hens in the UT were not dewormed and served as controls. Additionally, FECs on cloacal contents, worm fecundity and worm burdens were determined at 19, 35 and 45wpp. None of the flocks became infected until after 16wpp. The cumulative pooled FECs at the end of the study were significantly (p<0.01) lower in the TT compared to both CT and UT. Although repeated treatment in the TT protocol did not affect the fecundity, a worm density-dependent increase in fecundity was observed. Cloacal FECs and the number of adult A. galli in TT at 35 and 45wpp were significantly lower compared to other flocks. This study provides evidence that the TT strategy is better in terms of lower worm burden and decreased cumulative environmental parasite egg numbers compared to CT strategy. The TT strategy should be considered as an alternative to the CT strategy with regard to A. galli control in commercial laying hens.
MHC genes are key components in disease resistance and an excellent system for studying selection acting on genetic variation in natural populations. Current patterns of variation in MHC genes are ...likely to be influenced by past and ongoing selection as well as demographic fluctuations in population size such as those imposed by post-glacial recolonization processes. Here, we investigated signatures of historical selection and demography on an MHC class II gene in 12 moor frog populations along a 1700-km latitudinal gradient. Sequences were obtained from 207 individuals and consecutively assigned into two different clusters (northern and southern clusters, respectively) in concordance with a previously described dual post-glacial colonization route. Selection analyses comparing the relative rates of non-synonymous to synonymous substitutions (dN/dS) suggested evidence of different selection patterns in the northern and the southern clusters, with divergent selection prevailing in the south but uniform positive selection predominating in the north. Also, models of codon evolution revealed considerable differences in the strength of selection: The southern cluster appeared to be under strong selection while the northern cluster showed moderate signs of selection. Our results indicate that the MHC alleles in the north diverged from southern MHC alleles as a result of differential selection patterns.
Poultry roundworms have re-emerged in laying hens in many European countries due to the increase in noncaged housing. This is worrying because, at high parasite loads, Ascaridia galli can impact ...birds' welfare, health, and productivity. Worm control is therefore an important aspect of the successful management of the egg production industry. In 2009, the Swedish Egg Association initiated a voluntary control program to tackle the problem and reduce the appearance of worms in table eggs by encouraging producers to submit fecal samples for analysis. Since the start of the program, its data have never been thoroughly explored. Moreover, after more than a decade of challenges, our understanding of how egg producers perceive worm infection is still inadequate. This study was therefore designed to address these issues. The research data in the present study are drawn from 2 sources. First, through the control program and second, through an online survey. We have summarized the control program's achievements and discussed its findings and limitations. Although this work contributes to existing knowledge of roundworm control in laying hens in general, it also identifies gaps in knowledge. In conclusion, the control program can be improved by incorporating more strategic sampling and utilizing well-suited diagnostic tools for better assessment of infection status. It is equally important to educate producers on anthelmintics (AH) use and the development of resistance.
Faecal egg count reduction tests (FECRT) using ivermectin (IVM) and benzimidazole (BZ) were conducted to investigate the prevalence of anthelmintic resistance in gastro-intestinal nematodes on cattle ...farms in Germany, Belgium and Sweden in 2006 and 2007. Based on sufficient numbers of eggs prior to the study, between 3 and 10 farms per country were selected. 10–15 animals were randomly selected per farm and subcutaneously treated with 0.2
mg IVM/kg bodyweight (Ivomec
®, Merial). Faecal samples were collected individually from every animal on day 0 (treatment), day 7 (Belgium & Sweden) or 14 (Germany), and day 21 (Germany, Belgium and Sweden). Faecal egg counts (FEC) were performed at each sampling occasion to estimate the eggs per gram of faeces (EPG) and the reduction of eggs after treatment. The FECRT using IVM in 2006 revealed mean reduction of egg counts between 69–100% on day 7/14 (95% confidence interval (CI) 19–102) and 35–96% (95% CI 0–102) on day 21. Farms with a suggested problem of anthelmintic resistance have been re-visited in 2007 and except for one case all results obtained in 2006 were confirmed in 2007. Larvae obtained from faecal cultures were identified using microscopic identification keys or genus-specific real time PCR.
Cooperia oncophora was the predominant species detected after treatment, but
Ostertagia ostertagi was found in samples on 3 farms in Germany and 3 farms in Sweden post-treatment.
In 2007 additionally a FECRT using benzimidazoles was conducted in Germany and Sweden. In Germany oral Valbazen
® (albendazole, 10%, Pfizer) was used at a concentration of 7.5
mg albendazole/kg bodyweight; in Sweden Valbazen Vet
® (albendazole, 10%, Orion Pharma) at a dose of 8
mg/kg was used. For benzimidazoles an efficacy of 100% was obtained on all tested farms in both countries. This is the first report of a multinational anthelmintic efficacy investigation in cattle in Europe. The results suggest that testing of anthelmintic efficacy should be performed more intensively due to possible insufficient efficacy of current drugs.
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