Dataset Information

Assessment of laying-bird welfare following acaricidal treatment of a commercial flock naturally infested with the poultry red mite (Dermanyssus gallinae).

ABSTRACT: The poultry red mite (PRM), Dermanyssus gallinae, a potential vector of pathogens to animals and humans, causes impaired bird welfare. A study investigated changes in behavioural variables, physiological biomarkers, and health parameters following acaricidal treatment of PRM infestation of laying hens on a commercial farm. Mite traps determined the challenge to 12,700 hens before and after drinking water administration of the acaricide, fluralaner (Exzolt®, 0.5 mg/kg; Weeks 0 and 1). Weekly daytime direct observations and night-time video recordings monitored bird behaviours from Weeks -6 through +6. Blood samples were collected from randomly-selected birds (Weeks -6, -1, and +6). Following treatment, mite count reductions (>99%) were statistically significant (P < 0.0001), as were night-time reductions in the percent of hens showing activity, preening, head scratching (all P < 0.0001), and head shaking (P = 0.0007). Significant daytime reductions were observed in preening and head scratching (both P < 0.0001), head shaking (P = 0.0389), severe feather pecking (P = 0.0002), and aggressive behaviour (P = 0.0165). Post-treatment, comb wounds were significantly reduced (P = 0.0127), and comb colour was significantly improved (P < 0.0001). Heterophil/lymphocyte ratio was significantly reduced at Weeks 1 and 6 (P = 0.0009 and P < 0.0001, respectively). At Week 6, blood corticosterone (P = 0.0041) and total oxidant status (P < 0.0001) were significantly reduced, and haemoglobin and mean corpuscular haemoglobin significantly increased (P < 0.0001). Farm production records indicated that those post-treatment improvements were accompanied by significant reductions in weekly mortality rate (P = 0.0169), and significant recovery in mean weekly egg weights (P < 0.0001) and laying rate (P < 0.0001). The improvements in behavioural variables, physiological biomarkers, and health parameters that were observed following the elimination of PRM on a commercial farm indicate that infestations can be a cause of reduced hen welfare.

SUBMITTER: Temple D

PROVIDER: S-EPMC7676655 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Assessment of laying-bird welfare following acaricidal treatment of a commercial flock naturally infested with the poultry red mite (Dermanyssus gallinae).

Temple Déborah D Manteca Xavier X Escribano Damián D Salas Marina M Mainau Eva E Zschiesche Eva E Petersen Ivo I Dolz Roser R Thomas Emmanuel E

PloS one 20201119 11

The poultry red mite (PRM), Dermanyssus gallinae, a potential vector of pathogens to animals and humans, causes impaired bird welfare. A study investigated changes in behavioural variables, physiological biomarkers, and health parameters following acaricidal treatment of PRM infestation of laying hens on a commercial farm. Mite traps determined the challenge to 12,700 hens before and after drinking water administration of the acaricide, fluralaner (Exzolt®, 0.5 mg/kg; Weeks 0 and 1). Weekly dayt ...[more]

PMID: 33211741

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Project description:BackgroundThe worldwide distributed hematophagous poultry red mite Dermanyssus gallinae (De Geer, 1778) is one of the most important pests of poultry. Even though 35 acaricide compounds are available, control of D. gallinae remains difficult due to acaricide resistances as well as food safety regulations. The current study was carried out to identify putative excretory/secretory (pES) proteins of D. gallinae since these proteins play an important role in the host-parasite interaction and therefore represent potential targets for the development of novel intervention strategies. Additionally, putative transmembrane proteins (pTM) of D. gallinae were analyzed as representatives of this protein group also serve as promising targets for new control strategies.MethodsD. gallinae pES and pTM protein prediction was based on putative protein sequences of whole transcriptome data which was parsed to different bioinformatical servers (SignalP, SecretomeP, TMHMM and TargetP). Subsequently, pES and pTM protein sequences were functionally annotated by different computational tools.ResultsComputational analysis of the D. gallinae proteins identified 3,091 pES (5.6%) and 7,361 pTM proteins (13.4%). A significant proportion of pES proteins are considered to be involved in blood feeding and digestion such as salivary proteins, proteases, lipases and carbohydrases. The cysteine proteases cathepsin D and L as well as legumain, enzymes that cleave hemoglobin during blood digestion of the near related ticks, represented 6 of the top-30 BLASTP matches of the poultry red mite's secretome. Identified pTM proteins may be involved in many important biological processes including cell signaling, transport of membrane-impermeable molecules and cell recognition. Ninjurin-like proteins, whose functions in mites are still unknown, represent the most frequently occurring pTM.ConclusionThe current study is the first providing a mite's secretome as well as transmembranome and provides valuable insights into D. gallinae pES and pTM proteins operating in different metabolic pathways. Identifying a variety of molecules putatively involved in blood feeding may significantly contribute to the development of new therapeutic targets or vaccines against this poultry pest.

Project description:BACKGROUND:The poultry red mite (PRM), Dermanyssus gallinae, is one of the most economically deleterious ectoparasites affecting egg-laying hens worldwide. It may be possible to control D. gallinae populations by manipulating lighting regimes within poultry units. However, no studies have clearly shown the effects of darkness on the population growth rate of D. gallinae. METHODS:The effect of darkness on the population growth rate of D. gallinae was investigated, together with the first description of the molecular identity of the mite from China. Mite variables under two lighting regimens (1:23 h L:D and 12:12 h L:D) were compared, including number of mites and eggs, survival and feeding rates, engorgement, oviposition, hatchability and the life-cycle of D. gallinae. RESULTS:The results showed that the number of mites (13,763?±?956) and eggs (5424?±?317) in the rearing system with prolonged darkness of 1:23 h L:D at 4th week were 2.4- and 3.6-fold higher than those under a conventional lighting regimen of 12:12 h L:D, respectively. The feeding rates of mites under prolonged darkness ranged from 36.7?±?1.1% to 52.0?±?7.0%, which were significantly higher than those under conventional lighting regimen (ranging from 22.6?±?1.9% to 37.3?±?1.6%). The mean weight of engorged females (0.26?±?0.01 mg) and the mean number of eggs per female (on average 5.87?±?0.36) under prolonged darkness were significantly higher than those under conventional lighting regimen (0.22?±?0.01 mg and 3.62?±?0.31, respectively). However, the survival rate ranging from 98.07?±?0.10% to 98.93?±?0.19%, hatchability of 97.93?±?0.01% and the life-cycle of D. gallinae (9 days) was not affected by the lighting period. CONCLUSIONS:Our findings demonstrated that prolonged darkness significantly promoted the proliferation levels of D. gallinae, resulting in increased number of mites and eggs in the rearing system. The promoted population growth of D. gallinae was found to be related to the increased feeding rate, engorgement level and oviposition level of mites under prolonged darkness. The egg hatchability, the survival rates and the duration of life-cycle of D. gallinae were not affected by the light regimes.

Dataset Information

Assessment of laying-bird welfare following acaricidal treatment of a commercial flock naturally infested with the poultry red mite (Dermanyssus gallinae).

Publications

Assessment of laying-bird welfare following acaricidal treatment of a commercial flock naturally infested with the poultry red mite (Dermanyssus gallinae).

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