The Experts below are selected from a list of 45369 Experts worldwide ranked by ideXlab platform

Bradley A. Mullens - One of the best experts on this subject based on the ideXlab platform.

  • Housing and dustbathing effects on northern fowl mites (Ornithonyssus sylviarum) and chicken body lice (Menacanthus stramineus) on Hens
    Medical and Veterinary Entomology, 2012
    Co-Authors: C. D. Martin, Bradley A. Mullens
    Abstract:

    Hen housing (cage or cage-free) did not impact overall abundances of northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), or chicken body lice, Menacanthus stramineus (Nitzsch) (Phthiraptera: Menoponidae). Cage-free Hens received a dustbox with sand plus diatomaceous earth (DE), kaolin clay or sulphur. Weekly use varied from none to 100% of Hens; 73% of Hens used the dustbox at least once. Ectoparasite populations on dustbathing Hens (users) were compared with those on non-user cage-free and caged Hens. All materials reduced ectoparasites on user Hens by 80-100% after 1 week of dustbox use. Diatomaceous earth and kaolin failed to reduce ectoparasites on non-user Hens, and ectoparasites on user Hens recovered after dustbox removal. A sulphur dustbox eliminated mites from all Hens (including non-users) within 2-4 weeks. Residual sulphur controlled mites until the end of the experiment (up to 9 weeks), even after the dustbox was removed. Louse populations on Hens using the sulphur dustbox were reduced in 1-2 weeks. Residual sulphur effects were less evident in lice, but the use of a sulphur dustbox by a higher proportion of Hens extended louse control to all Hens. This is the first experimental study to show that bird dustbathing in naturally and widely available dust materials (particularly kaolin) can suppress ectoparasites and thus the behaviour is probably adaptive.

  • beak condition and cage density determine abundance and spatial distribution of northern fowl mites ornithonyssus sylviarum and chicken body lice menacanthus stramineus on caged laying Hens
    Poultry Science, 2010
    Co-Authors: Bradley A. Mullens, B L Chen, Jeb P Owen
    Abstract:

    Abstract Adult White Leghorn Hens (Hy-Line strain W-36) were inoculated with either northern fowl mites or chicken body lice, and the ectoparasite populations were monitored over periods of 9 to 16 wk. Two beak conditions (beak trimmed or beak intact) and 2 housing densities (1 or 2 Hens per 25 × 31 cm suspended wire cage) were tested. Populations of both ectoparasites were at least 10 times lower on beak-intact Hens compared with populations on beak-trimmed Hens. Cage density did not influence mite numbers, but higher numbers of lice (2 to 3 times) developed on Hens held at the higher cage density. Louse distribution on the body and louse population age structure were also influenced by host beak condition. Beak-intact Hens had a higher proportion of lice under the wings, whereas beak-trimmed Hens had the majority of lice on the lower abdomen. Louse populations on beak-trimmed Hens also comprised relatively more immature stages than populations found on beak-intact Hens. The effects are likely related to decreased grooming efficiency by beak-trimmed Hens and, in the case of lice, the higher host density. The high mite and louse populations on most commercial caged laying Hens are probably a direct result of beak trimming. However, selection of more docile breeds that can be held without trimming may allow the Hens themselves to reduce ectoparasites below economically damaging levels. This could benefit producers, animal welfare advocates, and human health by reducing 1) costs of beak trimming, 2) pesticide treatment costs (including human and bird chemical exposure concerns), and 3) objections to beak trimming from the animal welfare community.

C. D. Martin - One of the best experts on this subject based on the ideXlab platform.

  • Housing and dustbathing effects on northern fowl mites (Ornithonyssus sylviarum) and chicken body lice (Menacanthus stramineus) on Hens
    Medical and Veterinary Entomology, 2012
    Co-Authors: C. D. Martin, Bradley A. Mullens
    Abstract:

    Hen housing (cage or cage-free) did not impact overall abundances of northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), or chicken body lice, Menacanthus stramineus (Nitzsch) (Phthiraptera: Menoponidae). Cage-free Hens received a dustbox with sand plus diatomaceous earth (DE), kaolin clay or sulphur. Weekly use varied from none to 100% of Hens; 73% of Hens used the dustbox at least once. Ectoparasite populations on dustbathing Hens (users) were compared with those on non-user cage-free and caged Hens. All materials reduced ectoparasites on user Hens by 80-100% after 1 week of dustbox use. Diatomaceous earth and kaolin failed to reduce ectoparasites on non-user Hens, and ectoparasites on user Hens recovered after dustbox removal. A sulphur dustbox eliminated mites from all Hens (including non-users) within 2-4 weeks. Residual sulphur controlled mites until the end of the experiment (up to 9 weeks), even after the dustbox was removed. Louse populations on Hens using the sulphur dustbox were reduced in 1-2 weeks. Residual sulphur effects were less evident in lice, but the use of a sulphur dustbox by a higher proportion of Hens extended louse control to all Hens. This is the first experimental study to show that bird dustbathing in naturally and widely available dust materials (particularly kaolin) can suppress ectoparasites and thus the behaviour is probably adaptive.

Wayne L Bacon - One of the best experts on this subject based on the ideXlab platform.

  • Frequency of luteinizing hormone surges and egg production rate in turkey Hens
    2016
    Co-Authors: -k. H. Liu, David W Long, K. E. Nestor, Wayne L Bacon
    Abstract:

    Whether the interval between preovulatory surges of LH was different between lines of turkey Hens with either poor (RBC3 line, peak at 55%) or excellent rate of egg production (Egg line, peak at 85%) was examined. Laying Hens were cannulated and bled hourly for 10 days at peak of production. A constant light photoschedule was used to avoid diurnal masking of innate cir-cadian rhythms. The mean interval between LH surges in the RBC3 line was longer than in the Egg line and had a higher coefficient of variation. A few longer LH surge intervals (.72 h) were found in some RBC3 line Hens (2 of 7 Hens), but none were found in Egg line Hens (0 of 11 Hens). All progesterone (P4) surges were coupled with LH surges, but not all LH-P4 surges were coupled with ovipositions (blind LH-P4 surges). The per-centage of blind LH-P4 surges was not different between lines. The baseline concentration of LH was higher in Egg line than RBC3 line Hens, but LH surge amplitude, and surge duration were not different. The baseline and surge amplitude concen-trations of P4 were not different between lines, nor was the con-centration of estradiol-17b. The longer interval between LH surges was the major factor tested that was associated with the poorer egg production rate in RBC3 line Hens in comparison to Egg line Hens. A higher incidence of blind LH surges further contributed to lower egg production in RBC3 line turkey Hens. estradiol, luteinizing hormone, ovulation, ovulatory cycle, pro-gesteron

  • duration of the reproductive period decreases the frequency of preovulatory luteinizing hormone surges in heavy weight sire line turkey Hens
    General and Comparative Endocrinology, 2005
    Co-Authors: Hanken Liu, David W Long, Wayne L Bacon
    Abstract:

    Abstract The frequency of preovulatory luteinizing hormone (LH) surges is an important determinant of ovulation and oviposition rates in turkeys. Egg production rate is relatively poor in heavy weight-sire line type turkey Hens and declines with advancing duration of the reproductive period. The purpose of this study was to measure frequency and characteristics of preovulatory LH surges in turkey Hens of a heavy weight-sire line type early, at peak of egg production (Early), and late, after egg production rate had declined (Late), in a reproductive period. The Early Hens were photostimulated with a continuous photoperiod [24 h light (L):0 h dark (D)] at 40 weeks of age and sampled during peak egg production at about 47 weeks of age. The Late Hens were photostimulated at 40 weeks of age with a long day photoperiod (14L:10D). After a 27-week egg production period, the Late Hens were switched to the 24L:0D photoperiod and sampled at 74 weeks of age. Continuous lighting was used during blood sampling to allow the rhythm of preovulatory LH surges to free run. All Hens were cannulated 3–5 days before starting sampling and hourly blood samples were collected for 200 h. All Hens were necropsied and ovarian and oviductal morphologies were measured after serial bleeding. The Late Hens had a longer interval between intra-clutch preovulatory LH surges than the Early Hens, and a higher incidence of atretic ovarian follicles. The Early Hens had higher baseline and surge amplitude LH concentrations but lower progesterone (P 4 ) surge amplitude concentrations than the Late Hens. The duration of preovulatory LH surges, incidence of “blind” preovulatory LH surges, baseline P 4 concentrations, and overall estradiol-17β (E 2 ) concentrations were not different between Early and Late Hens. In conclusion, a longer interval between preovulatory LH surges, lower LH baseline and surge amplitude concentrations, a higher incidence of atretic follicles, and higher P 4 surge amplitude concentration were associated with the decline in egg production late in the reproductive period in a heavy weight-sire line of turkey Hens.

  • concentration change patterns of luteinizing hormone and progesterone and distribution of hierarchical follicles in normal and arrested laying turkey Hens
    Poultry Science, 2001
    Co-Authors: H K Liu, David W Long, Wayne L Bacon
    Abstract:

    Young photosensitive turkey Hens of a line selected for increased egg production (Egg line) were photostimulated with constant light [24 h light:0 h darkness] at 30 wk of age. Egg laying became arrested in 6 of 12 the Hens after only 2 to 3 wk of laying. Ovarian morphology and changes in concentrations of plasma hormones [luteinizing hormone (LH), progesterone (P4), and estradiol-17beta (E2)] over 10 d of serial bleeding were compared between the arrested laying and normal laying Hens. The number of ovarian follicles heavier than 1.0 g was much greater in arrested laying Hens, and some of the arrested laying Hens presented a polycystic ovarian follicle condition. The oviducts of the arrested laying Hens were fully developed and were similar in weight to those of normal laying Hens. In arrested laying Hens the plasma concentration of LH was relatively low (1.72 +/- 0.30 ng mL(-1)) and without preovulatory surges. In normal laying Hens the baseline concentration of LH was 2.60 +/- 0.71 ng mL(-1), and the interval between LH surges was 26.8 h. In the arrested laying Hens, the plasma concentration of P4 was relatively high (4.66 +/- 1.28 ng mL(-1)) and without preovulatory surges. In normal laying Hens the baseline concentration of P4 between surges was 1.76 +/- 0.24 ng mL(-1). Plasma E2 concentrations were not different between normal laying and arrested laying Hens. In conclusion, ovulations and ovipositions ceased in the arrested laying Hens, but the entrance of follicles into the follicular hierarchy and hierarchical growth continued, leading to an accumulation of numerous mature follicles in the ovary. In addition, some of the accumulated mature follicles might have resumed growing, leading to the formation of cystic ovarian follicles.

  • preovulatory luteinizing hormone surge interval in old and young laying turkey Hens early in the egg production period
    Poultry Science, 2001
    Co-Authors: H K Liu, David W Long, Wayne L Bacon
    Abstract:

    Egg production rate normally declines with duration of the reproductive period, but hen age and duration of the reproductive period are usually confounded. Initiation of egg production can be delayed in turkey Hens with short-day lighting, allowing hen age to be separated from duration of the reproductive period. The objective of the present report is to determine if the interval between luteinizing hormone (LH) surges is different between old and young laying turkey Hens during the peak of egg production. Turkey Hens were given short-day lighting [6 h light (L):18 h darkness (D)] at 16 wk of age, and were photostimulated with 24L:OD (constant light) at 30 (young Hens) or at 70 (old Hens) wk of age. Egg production in the young Hens started about 2 wk after they were photostimulated, but some of the old Hens had started laying at 64 wk of age while under short-day lighting, and all old Hens were laying after 1 wk of photostimulation. To monitor the interval between plasma LH surges at peak of production, Hens were serially bled hourly for 240 h, starting about 6 wk after photostimulation. The interval of LH surges was not different between young (n = 5) and old (n = 10) laying Hens. Not all LH surges were coincident with oviposition of eggs 1 to 2 d later (blind LH surges), and the percentage of young Hens with at least one blind LH surge was higher than for old Hens (60% of young Hens and 10% of old Hens). The baseline concentration of LH was not different between the young and old laying Hens. In conclusion, the interval between LH surges, baseline concentration of LH, and amplitude of LH surges were not related to age of the Hens during the peak rate of lay.

D M Karcher - One of the best experts on this subject based on the ideXlab platform.

  • research note horizontal transmission and internal organ colonization by salmonella enteritidis and salmonella kentucky in experimentally infected laying Hens in indoor cage free housing
    Poultry Science, 2020
    Co-Authors: Richard K Gast, D R Jones, Rupa Guraya, K E Anderson, D M Karcher
    Abstract:

    The transmission of Salmonella to humans via contaminated eggs is an international public health concern. S. Enteritidis is deposited inside eggs after colonizing reproductive tissues of infected Hens. Diverse housing facility characteristics and flock management practices influence Salmonella persistence and transmission in poultry, but the food safety consequences of different housing systems for laying Hens remain unresolved. The present study compared the horizontal transmission of infection and invasion of internal organs during the first 2 wk after experimental S. Enteritidis and S. Kentucky infection of laying Hens in indoor cage-free housing. Groups of 72 Hens were housed in isolation rooms simulating commercial cage-free barns, and 1/3 of the Hens in each room were orally inoculated with either S. Enteritidis (2 rooms) or S. Kentucky (2 rooms). At 6 d and 12 d postinoculation, 12 inoculated and 24 contact-exposed Hens in each room were euthanized, and samples of liver, spleen, ovary, oviduct, and intestinal tract were removed for bacteriologic culturing. All orally inoculated Hens were positive for intestinal colonization by S. Enteritidis at 6 d postinfection, and 70.8% of contact-exposed Hens had become colonized by 12 d. S. Enteritidis was isolated from 100% of livers and 50.0% of ovaries from inoculated birds at 6 d and from 41.7% of livers and 10.4% of ovaries from contact-exposed birds at 12 d. The majority of both orally inoculated and contact-exposed Hens were positive for intestinal colonization by S. Kentucky at 6 d, but S. Kentucky was found in other internal organs of both inoculated and contact-exposed Hens significantly (P < 0.05) less often than S. Enteritidis at both sampling intervals. These results indicate that Salmonella infection can spread rapidly and extensively among Hens in cage-free indoor housing, including a high frequency of internal organ involvement for invasive S. Enteritidis.

  • nighttime roosting substrate type and height among 4 strains of laying Hens in an aviary system
    Poultry Science, 2019
    Co-Authors: Ahmed Ali, D M Karcher, Dana L. M. Campbell, Janice M. Siegford
    Abstract:

    Multi-tiered aviaries for laying Hens are designed to provide resources, such as perches, that allow birds to perform natural behaviors, thus improving their welfare. This research examined nighttime roosting heights and substrates used by laying Hens of 4 genetic strains (Dekalb White: W1, Hy-Line W36: W2, Hy-Line Brown: B1, Bovans Brown: B2), in multitier aviaries (144 Hens/unit, 4 units/strain) at 25 to 28 wk of age (peak lay). Influence of litter provision on roosting patterns of the strains was also tested. Direct observations of Hens' nighttime roosting patterns on wire floors, ledges and perches across tiers were conducted before (PRE), immediately after (IMM), and 3 wk after (ACC) Hens gained access to litter. During all periods, more W1 and W2 Hens roosted on middle and upper ledges than B1 and B2 Hens (all P≤0.05), while more B1 and B2 Hens used perches throughout the aviary than W1 and W2 Hens (all P≤0.05). W1 (15±1.9, 14±3.36) and W2 (19±2.1, 18±2.6) Hens occupied perches in the upper tier in greater numbers than B1 (7±3.2, 3±4.6) and B2 (11±2.1, 5±3.36) Hens during PRE (P = 0.01) and ACC (P = 0.02) periods, respectively. B1 and B2 Hens occupied wire floors in larger numbers than W1 and W2 Hens during PRE (P = 0.02) and IMM (P = 0.03) periods, though this difference disappeared in the ACC period. During the IMM period, more W1 and W2 roosted in the lower tier, while more B1 and B2 Hens were observed in the middle and upper tiers (all P ≤ 0.05). These findings demonstrate the importance of perches for B1 and B2 Hens and space to roost higher in aviary units for W1 and W2 Hens during the night, and underscore the need to consider aviary design, management practices, and preferences of different hen strains to ensure good hen welfare in aviaries.

  • keel bone damage assessment consistency in enriched colony laying Hens
    Poultry Science, 2019
    Co-Authors: Nicholas J Chargo, C I Robison, Sydney L Baker, M J Toscano, M M Makagon, D M Karcher
    Abstract:

    Damage to the keel bone is a major issue in the laying hen industry. The goal of this study was to compare palpation results of live laying Hens to digital computed tomography (CT) images, to assess changes in palpation reliability as training and familiarity increased, and to examine keel bone morphology over time. The longitudinal study consisted of 2 trials of 3 observation periods using 40 different (n = 120) W-36 Hens housed in enriched colony cages. The first trial began when Hens were 52 to 58 wk of age repeating the trial when the same birds were 74 to 81 wk of age. At 52 wk of age, each hen's keel bone was palpated by a single individual for keel bone caudal tip fractures (Tip), sagittal deviations (Evenness), and transverse deviations (Straightness). After palpation, each hen was placed in a motion limiting restraint and scanned using CT. The Hens spent the next 21 d in their cages and on day 21, the Hens were collected, palpated, and CT scanned again. The CT scans were imported into Mimics analysis software, 3D models of each keel bone were constructed and evaluated. Each bone and 3D model was scored (0, 1, 2) on the measurement of transverse deviation based on 1.0 cm total deviation, respectively. Analysis of data using Proc Freq and Means in SAS 9.3 revealed minimal to moderate kappa values and moderate agreement percentages between palpators and digital analysis. The computer generated 3D models of individual keel bones were compared to palpation scores for Tip, Evenness, and Straightness at the beginning and end of each trial. The visual observations of the 3D models were qualitative, performed by a single individual. Overall, we found CT scanning to be a useful tool in observing changes to the keel bone, we observed changes in palpation accuracy as training/familiarity increased, and examined changes in keel morphology, specifically in the tip, after 52 wk of age.

  • laying Hens in aviaries with different litter substrates behavior across the flock cycle and feather lipid content
    Poultry Science, 2017
    Co-Authors: D M Karcher, Dana L. M. Campbell, J M Siegford
    Abstract:

    Abstract The tiered aviary for laying Hens includes a floor litter area to promote foraging and dust bathing. Data are needed on Hens’ use of different litter substrates and effectiveness of substrates in removing excess feather lipids to ensure a suitable litter area. Bovans White Hens were housed in commercial-style aviaries with access to one of 3 litter substrates (wood shavings, straw, or plastic turf mats—AstroTurf®, n = 4 aviary pens per substrate, 144 cage-reared Hens populated per pen). Litter areas were videoed across 2 d each at 4 ages: immediately following first aviary opening (25 wk), then at 28, 50, and 68 weeks. Observations of Hens throughout the d included percentages of all Hens in each pen on the litter area, foraging and transitioning between the tiered enclosure and litter area. Percentages of Hens dust bathing were observed from 11:00 to 15:00. Breast and back feather samples from 7 birds per pen at 28, 50, and 68 wk were analyzed for lipid content. Overall, fewer Hens simultaneously accessed the AstroTurf® (P

  • housing conditions alter properties of the tibia and humerus during the laying phase in lohmann white leghorn Hens
    Poultry Science, 2016
    Co-Authors: P Regmi, N Smith, N Nelson, Roger C Haut, M W Orth, D M Karcher
    Abstract:

    : Osteoporosis in caged Hens is one driving factor for the United States egg industry to explore options regarding alternative housing systems for laying Hens. The aim of our research was to study the influence of housing systems on tibiae and humeri of 77-week-old Lohmann White Hens. Pullets raised in an aviary system were either continued in aviary hen systems (AV) or conventional cages (AC) whereas pullets reared in conventional cages continued in conventional hen cages (CC) or enriched colony cages (EN) at 19 weeks. From each group, 120 Hens were randomly euthanized and right and left tibae and humeri were excised for structural and mechanical analysis. Volumetric density of the cortical bone was measured using quantitative computed tomography (QCT). Aviary (AV) Hens had greater cortical thickness and density but similar outer dimensions to AC Hens (P < 0.05). Hens in EN system had humeri with similar cortical thickness and density but wider outer dimensions than the humeri of CC Hens (P < 0.05). Cortical geometry of the tibiae was the same for the EN and CC Hens, whereas EN Hens had denser tibial cortex than CC Hens (P < 0.05). Geometrical changes in the humeri suggest that Hens in the AV system were better able to protect their structure from endosteal resorption during the laying phase. Humeri of AV and EN Hens had increased second moment of area compared to the AC and CC Hens; however, the changes were not observed in tibiae. Mechanical property differences were observed, with bones of AV Hens having greater failure moment and stiffness than AC Hens and the same difference was observed between the EN and CC Hens, (P < 0.05). These findings indicate that movement limitation causes loss of bone mass and density whereas provision of moderate movement increases certain bone quality parameters during adulthood in laying Hens.

David W Long - One of the best experts on this subject based on the ideXlab platform.

  • Frequency of luteinizing hormone surges and egg production rate in turkey Hens
    2016
    Co-Authors: -k. H. Liu, David W Long, K. E. Nestor, Wayne L Bacon
    Abstract:

    Whether the interval between preovulatory surges of LH was different between lines of turkey Hens with either poor (RBC3 line, peak at 55%) or excellent rate of egg production (Egg line, peak at 85%) was examined. Laying Hens were cannulated and bled hourly for 10 days at peak of production. A constant light photoschedule was used to avoid diurnal masking of innate cir-cadian rhythms. The mean interval between LH surges in the RBC3 line was longer than in the Egg line and had a higher coefficient of variation. A few longer LH surge intervals (.72 h) were found in some RBC3 line Hens (2 of 7 Hens), but none were found in Egg line Hens (0 of 11 Hens). All progesterone (P4) surges were coupled with LH surges, but not all LH-P4 surges were coupled with ovipositions (blind LH-P4 surges). The per-centage of blind LH-P4 surges was not different between lines. The baseline concentration of LH was higher in Egg line than RBC3 line Hens, but LH surge amplitude, and surge duration were not different. The baseline and surge amplitude concen-trations of P4 were not different between lines, nor was the con-centration of estradiol-17b. The longer interval between LH surges was the major factor tested that was associated with the poorer egg production rate in RBC3 line Hens in comparison to Egg line Hens. A higher incidence of blind LH surges further contributed to lower egg production in RBC3 line turkey Hens. estradiol, luteinizing hormone, ovulation, ovulatory cycle, pro-gesteron

  • duration of the reproductive period decreases the frequency of preovulatory luteinizing hormone surges in heavy weight sire line turkey Hens
    General and Comparative Endocrinology, 2005
    Co-Authors: Hanken Liu, David W Long, Wayne L Bacon
    Abstract:

    Abstract The frequency of preovulatory luteinizing hormone (LH) surges is an important determinant of ovulation and oviposition rates in turkeys. Egg production rate is relatively poor in heavy weight-sire line type turkey Hens and declines with advancing duration of the reproductive period. The purpose of this study was to measure frequency and characteristics of preovulatory LH surges in turkey Hens of a heavy weight-sire line type early, at peak of egg production (Early), and late, after egg production rate had declined (Late), in a reproductive period. The Early Hens were photostimulated with a continuous photoperiod [24 h light (L):0 h dark (D)] at 40 weeks of age and sampled during peak egg production at about 47 weeks of age. The Late Hens were photostimulated at 40 weeks of age with a long day photoperiod (14L:10D). After a 27-week egg production period, the Late Hens were switched to the 24L:0D photoperiod and sampled at 74 weeks of age. Continuous lighting was used during blood sampling to allow the rhythm of preovulatory LH surges to free run. All Hens were cannulated 3–5 days before starting sampling and hourly blood samples were collected for 200 h. All Hens were necropsied and ovarian and oviductal morphologies were measured after serial bleeding. The Late Hens had a longer interval between intra-clutch preovulatory LH surges than the Early Hens, and a higher incidence of atretic ovarian follicles. The Early Hens had higher baseline and surge amplitude LH concentrations but lower progesterone (P 4 ) surge amplitude concentrations than the Late Hens. The duration of preovulatory LH surges, incidence of “blind” preovulatory LH surges, baseline P 4 concentrations, and overall estradiol-17β (E 2 ) concentrations were not different between Early and Late Hens. In conclusion, a longer interval between preovulatory LH surges, lower LH baseline and surge amplitude concentrations, a higher incidence of atretic follicles, and higher P 4 surge amplitude concentration were associated with the decline in egg production late in the reproductive period in a heavy weight-sire line of turkey Hens.

  • concentration change patterns of luteinizing hormone and progesterone and distribution of hierarchical follicles in normal and arrested laying turkey Hens
    Poultry Science, 2001
    Co-Authors: H K Liu, David W Long, Wayne L Bacon
    Abstract:

    Young photosensitive turkey Hens of a line selected for increased egg production (Egg line) were photostimulated with constant light [24 h light:0 h darkness] at 30 wk of age. Egg laying became arrested in 6 of 12 the Hens after only 2 to 3 wk of laying. Ovarian morphology and changes in concentrations of plasma hormones [luteinizing hormone (LH), progesterone (P4), and estradiol-17beta (E2)] over 10 d of serial bleeding were compared between the arrested laying and normal laying Hens. The number of ovarian follicles heavier than 1.0 g was much greater in arrested laying Hens, and some of the arrested laying Hens presented a polycystic ovarian follicle condition. The oviducts of the arrested laying Hens were fully developed and were similar in weight to those of normal laying Hens. In arrested laying Hens the plasma concentration of LH was relatively low (1.72 +/- 0.30 ng mL(-1)) and without preovulatory surges. In normal laying Hens the baseline concentration of LH was 2.60 +/- 0.71 ng mL(-1), and the interval between LH surges was 26.8 h. In the arrested laying Hens, the plasma concentration of P4 was relatively high (4.66 +/- 1.28 ng mL(-1)) and without preovulatory surges. In normal laying Hens the baseline concentration of P4 between surges was 1.76 +/- 0.24 ng mL(-1). Plasma E2 concentrations were not different between normal laying and arrested laying Hens. In conclusion, ovulations and ovipositions ceased in the arrested laying Hens, but the entrance of follicles into the follicular hierarchy and hierarchical growth continued, leading to an accumulation of numerous mature follicles in the ovary. In addition, some of the accumulated mature follicles might have resumed growing, leading to the formation of cystic ovarian follicles.

  • preovulatory luteinizing hormone surge interval in old and young laying turkey Hens early in the egg production period
    Poultry Science, 2001
    Co-Authors: H K Liu, David W Long, Wayne L Bacon
    Abstract:

    Egg production rate normally declines with duration of the reproductive period, but hen age and duration of the reproductive period are usually confounded. Initiation of egg production can be delayed in turkey Hens with short-day lighting, allowing hen age to be separated from duration of the reproductive period. The objective of the present report is to determine if the interval between luteinizing hormone (LH) surges is different between old and young laying turkey Hens during the peak of egg production. Turkey Hens were given short-day lighting [6 h light (L):18 h darkness (D)] at 16 wk of age, and were photostimulated with 24L:OD (constant light) at 30 (young Hens) or at 70 (old Hens) wk of age. Egg production in the young Hens started about 2 wk after they were photostimulated, but some of the old Hens had started laying at 64 wk of age while under short-day lighting, and all old Hens were laying after 1 wk of photostimulation. To monitor the interval between plasma LH surges at peak of production, Hens were serially bled hourly for 240 h, starting about 6 wk after photostimulation. The interval of LH surges was not different between young (n = 5) and old (n = 10) laying Hens. Not all LH surges were coincident with oviposition of eggs 1 to 2 d later (blind LH surges), and the percentage of young Hens with at least one blind LH surge was higher than for old Hens (60% of young Hens and 10% of old Hens). The baseline concentration of LH was not different between the young and old laying Hens. In conclusion, the interval between LH surges, baseline concentration of LH, and amplitude of LH surges were not related to age of the Hens during the peak rate of lay.