Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Effects of eggshell temperature pattern during incubation on tibia characteristics of broiler chickens at slaughter age
    Güz, B.C. ; Molenaar, R. ; Jong, I.C. de; Kemp, B. ; Krimpen, M. van; Brand, H. van den - \ 2020
    Poultry Science 99 (2020)6. - ISSN 0032-5791 - p. 3020 - 3029.
    broiler chickens - eggshell temperature - incubation - leg health - tibia

    This study was designed to determine effects of eggshell temperature (EST) pattern in week 2 and week 3 of incubation on tibia development of broiler chickens at slaughter age. A total of 468 Ross 308 eggs were incubated at an EST of 37.8°C from incubation day (E) 0 to E7. Thereafter, a 2 × 2 factorial arrangement with 2 EST (37.8°C and 38.9°C) from E8 to E14 and 2 EST (36.7°C and 37.8°C) from E15 till hatch was applied. After hatching, chickens were reared until slaughter age with the 4 EST treatments and 8 replicates per treatment. At day 41 and 42, one male chicken per replicate per day was selected, and hock burn and food pad dermatitis were scored. Rotated tibia, tibia dyschondroplasia, epiphyseal plate abnormalities, bacterial chondronecrosis with osteomyelitis, and epiphysiolysis were assessed. Tibia weight, length, thickness, head thickness, and robusticity index were determined. X-ray analyses (osseous volume, pore volume, total volume, volume fraction, mineral content, and mineral density) and a 3-point bending test (ultimate strength, yield strength, stiffness, energy to fracture, and elastic modulus) were performed. A high EST (38.9°C) in week 2 of incubation, followed by a normal EST (37.8°C) in week 3 resulted in higher mineral content (P = 0.001), mineral density (P = 0.002), ultimate strength (P = 0.04), yield strength (P = 0.03), and stiffness (P = 0.05) compared with the other 3 EST groups (week 2 × week 3 interaction). A high EST (38.9°C) in week 2 of incubation, regardless of the EST in week 3, resulted in a higher tibia weight (P < 0.001), thickness (P = 0.05), osseous volume (P < 0.001), and total volume (P < 0.001) than a normal EST (37.8°C). It can be concluded that 1.1°C higher EST than normal in week 2 of incubation appears to stimulate tibia morphological, biophysical, and mechanical characteristics of broiler chickens at slaughter age. Additionally, a 1.1°C lower EST in week 3 of incubation appears to have negative effects on tibia characteristics, particularly in interaction with the EST in week 2 of incubation.

    Effect of constant or weekly varied eggshell temperature during incubation on broiler performance up until slaughter age
    Wijnen, H.J. ; Roovert-Reijrink, Inge van; Eijk-Priester, Marieke van; Pol, C. van der; Molenaar, R. ; Brand, H. van den - \ 2018
    In: The XVth European Poultry Conference (EPC). - Zagreb, Croatia : Croatian Branch of the World's Poultry Science Association - ISBN 9789082915709 - p. 498 - 498.
    broiler - eggshell temperature - incubation - performance - compensatory growth - delayed nutrition - early nutrition
    After hatching in conventional systems, broiler chickens have a delay to nutrition thatcan last for 72h, depending on length of the hatch window, internal hatchery proceduresand transport duration. Previous research on early life feeding strategies has shownnegative effects on bodyweight (BW) gain after delayed nutrition (DN), compared withearly nutrition (EN). However, it is not known whether DN chickens can (partially)compensate for their lower BW between hatch and slaughter. In this study, we tested thehypothesis that DN chickens have an increased growth rate, as a result of compensatorygrowth. Data from 3 independent experiments were used. In these studies, broilerswere subjected to either EN or DN with different durations of DN (38 to 72 h) and daysto slaughter (14 to 35 d). In all experiments, DN groups had lower BW compared withEN which was sustained until slaughter. Relative differences in BW, however, decreasedfrom 114 to 176% post placement to 102 – 112 % at slaughter (35 d). Growth curves of DNand EN chickens were analysed to study whether compensatory growth could explain thedifferences in BW between EN and DN. Absolute average daily gain (aADG) was higher inEN chickens from start until slaughter. To analyse the growth curve independent of BW,relative ADG (rADG) between two ages was calculated as follows:Differences in rADG between DN and EN chickens were greater in the first 14 d (DN:63%, EN: 47%; P < 0.001), but smaller in the remaining grow-out period (14 – 28 d:DN: 18%, EN: 16%; 28 – 35 d: DN: 8%, EN: 7%; both P <0 .001). Based on these results,it seems that DN broilers compensate for their lag in BW during the first 14 d postplacement. As differences in absolute BW were still present at 35 d, the increase in rADGseems insufficient to catch up with EN broilers. EN chickens have higher aADG untilslaughter, however, rADG is lower, showing that growth rate is influenced by feedingstrategy. Previous literature describes interactions between compensatory growth andnutrient composition of diets on nitrogen and fat retention. This may give reason forfuture work to evaluate effects of early life feeding strategy on carcass traits.
    Applying cold incubation profiles during the last week of incubation in a commercial incubator: effects on broiler embryonic mortality, hatchability, and chick quality
    Roovert, Inge van; Eijk-Priester, Marieke van; Wijnen, H.J. ; Pol, C. van der - \ 2018
    In: The XVth European Poultry Conference (EPC). - Zagreb, Croatia : Croatian Branch of the World's Poultry Science Association - ISBN 9789082915709 - p. 126 - 126.
    chick quality - eggshell temperature - hatchability - incubation
    During incubation, an eggshell temperature (EST, as a reflection of embryo temperature) of 37.8°C was long considered to be optimal for broiler embryonic development. However, an EST of 36.7°C (Cold) from embryonic day (E)15 onward may result in a more developed heart at hatching than 37.8°C EST throughout (Control; Maatjens et al., 2016). Maatjens et al.’s study was performed in large incubation chambers with low air velocity, unlike commercial practice. To study Cold EST in a commercial situation with high air velocity and egg density, three trials were conducted. In all trials, EST for Cold was maintained at 37.8°C, decreased to 36.7°C with varying profiles in the last week, and then maintained at 36.7°C till hatching. Cold treatments were always compared to Control (37.8°C EST throughout incubation). 3,000-10,800 broiler eggs from a 30-39 week old parent flock were used. Firstly, EST was decreased within 30 minutes, on E15. Compared to Control, Cold resulted in 2.5x higher embryonic mortality around the time of the EST decrease (P = 0.015), 2.2% more second grade chicks (P = 0.049), and chicks were 0.4cm shorter (indicating lower development) at hatch (P = 0.001). Possibly, the EST decrease happened too early or abruptly. Secondly, EST was decreased gradually in 1 day, from E16-E17. No differences were found in hatchability (P = 0.68) or chick length (P = 0.93), but embryonic mortality around the time of the EST decrease tended to be 1.7x higher for Cold than for Control (P = 0.070). It was thought that an even slower EST decrease may optimize Cold further. Thirdly, EST was decreased using three different profiles. EST was decreased gradually from E16-E17, or quickly (to 36.9°C on E17) and then slowly (to 36.7°C on E18), or slowly (to 37.5°C on E17) and then quickly (to 36.7°C on E18). Embryonic mortality, hatchability, and navel quality did not differ between the Cold profiles and Control (P > 0.29). To conclude, results differed from the low air velocity trial situation. When EST was decreased from 37.8°C to 36.7°C abruptly or too early in development, hatchability and chick quality decreased. A slow transition from E16-E18 can result in chick quality and hatchability similar to Control. Knowledge on these optimal EST decrease profiles can be used to further investigate the effect of Cold incubation during the last days of incubation on post hatch performance and possibly apply it to commercial practice.
    The effect of different eggshell temperature patterns during incubation on broiler chicken behavior determined by an automatic tracking system
    Molenaar, R. ; Haas, E.N. de; Rodenburg, T.B. ; Olde Bolhaar, Lara ; Wijnen, H.J. ; Brand, H. van den - \ 2018
    In: The XVth European Poultry Conference (EPC). - Zagreb, Croatia : Croatian Branch of the World's Poultry Science Association - ISBN 9789082915709 - p. 248 - 248.
    behaviour - broiler chicken - incubation - tracking - compensatory growth - delayed nutrition - early nutrition

    Effect of constant or weekly varied eggshell temperature during incubation on broiler performance up until slaughter age
    Wijnen, H.J. ; Roovert-Reijrink, Inge Van; Priester, Marieke ; Pol, C.W. van der; Molenaar, R. ; Brand, H. van den - \ 2018
    broiler - eggshell temperature - incubation - performance - compensatory growth - delayed nutrition - early nutrition
    During incubation, embryo development is particularly influenced by temperature. Thevast majority of commercial hatcheries aim at a constant eggshell temperature (EST) of37.8°C throughout incubation. However, it has been shown recently that lowering EST(36.7°C) in the last week of incubation might improve embryo development, as higher(yolk-free) body mass and relative organ weights at hatch were found. In addition,raising EST slightly in phases during which oxygen is not limited yet (before the lastweek of incubation), might improve embryo development as well. It is hypothesizedthat a lower EST (36.7°) in the last week of incubation and a higher EST (38.9°C) in thesecond week of incubation improve embryo development and perinatal chick qualitycompared to a constant intermediate EST (37.6°) throughout incubation. Moreover,EST during incubation might have long term effects on broiler performance as theincubation period covers a substantial part of their whole lifespan and as it is knownfor many animal species that perinatal experiences have an impact in later life. Totest this hypothesis, Ross 308 eggs from a prime parent flock were incubated in a 2x2experimental design. All eggs were incubated at a normal (37.8°C) EST until embryonicday (E) 7. Thereafter, eggs were either incubated at a normal (37.8°C) or high (38.9°C)EST during the second week (E7 – E14) of incubation and a normal (37.8°C) or low(36.7°C) EST during the last week (E14 – E21) of incubation. Within 6 hours afterhatch, chick development was evaluated by chick weight, length, navelscore, and organweights. Posthatch, 5 males and 5 females were housed in a 2 m2 pen with 8 replicatesper treatment (n=320) and reared until slaughter age (D42). Growth and feed intakewere monitored weekly. At D28, D35, and D39 gait was scored from all animals. Atslaughter, foot-pad dermatitis, hock burns, and carcass characteristics were determined.Preliminary results indicate that a low EST from E15 onwards results in slower growthand on average 103 g. lower body weight at slaughter. Other parameters were notsignificantly different or not analysed yet (e.g. carcass characteristics) at the moment ofabstract submission.
    Bringing eggs and bones to light : affecting leg bone development in broiler chickens through perinatal lighting schedules
    Pol, Carla W. van der - \ 2017
    Wageningen University. Promotor(en): B. Kemp, co-promotor(en): H. van den Brand; I.A.M. Roovert-Reijrink. - Wageningen : Wageningen University - ISBN 9789463431422 - 214
    broilers - limb bones - biological development - embryonic development - eggs - light regime - incubation - hatching - circadian rhythm - animal pathology - animal health - poultry farming - vleeskuikens - beenderen van ledematen - biologische ontwikkeling - embryonale ontwikkeling - eieren - lichtregiem - broeden - uitbroeden - circadiaan ritme - dierpathologie - diergezondheid - pluimveehouderij

    Leg bone pathologies are a common problem in broiler chickens, and they can lead to decreased welfare and poor production performance. It can be speculated that the ae­tiology of some leg bone pathologies lies, to some extent, in suboptimal early life bone development. One factor that can be speculated to affect bone development, and conse­quently leg health, in broiler chickens is application of light. Light has several properties, such as light intensity, color, duration, and schedule. The present thesis focuses on ligh­ting schedules. Aim was to investigate how lighting schedules applied during incubation and in the early post hatch period (the brooding period) affected leg bone development throughout a broiler’s life and leg health at slaughter age.

    In 4 studies, effects of eggshell temperature (EST) and lighting schedule during incuba­tion and in the brooding period on leg bone development, leg health, and production parameters were explored. The first study found that an EST of 39.4°C led to lower bone dimensions at hatch than an EST between 37.8 and 38.6°C. It was then decided that incubation experiments on bone development would best be performed at a constant EST of 37.8°C, as this is also an EST that leads to good hatchability and chick quality. In two studies, the effects of circadian lighting schedules during incubation on leg bone development and leg health were investigated. Staining of the embryonic leg bones sho­wed that applying a circadian lighting schedule of 12 hours of light, followed by 12 hours of darkness (12L:12D) resulted in an earlier onset of embryonic ossification of the tibia than continuous light (24L). Compared to 24L, 12L:12D furthermore resulted in higher tibia weight and length, and higher tibial cortical area, cortical thickness, and second moment of area around the minor axis at hatch as revealed by MicroCT scanning. It was furthermore found that 12L:12D resulted in a lower incidence of the leg pathology tibial dyschondroplasia. Continuous darkness (24D) was mostly intermediate. On the other hand, a circadian lighting schedule of 16 hours of light, followed by 8 hours of darkness (16L:8D) did not show the same stimulatory effect on leg bone development, as no dif­ferences in gene expression markers involved in embryonic ossification were found, leg bone dimensions at hatch were not increased, and bone mineral content as determined by DXA scanning was not higher for 16L:8D. It can therefore be speculated that the dark period should exceed 8 hours per day during incubation for increased bone dimensions and ossification. However, incidence and severity of the leg bone pathologies in the form of bacterial chondronecrosis with osteomyelitis and epiphyseal plate abnormalities were lowest for broilers exposed to 16L:8D during incubation, and tibial dyschondroplasia tended to be lower for 16L:8D than for 24D. Interactions between incubation and mat­ching or mismatching post hatch lighting schedules were not found. It was speculated that the endocrine factors (pineal) melatonin, growth hormone, corticosterone, and IGF- 1 were a pathway through which light affected leg bone development, but no evidence was found to support this hypothesis. Production performance was not greatly influen­ced by incubation lighting schedule, but 24L was found to result in higher body weights at slaughter age than 16L:8D and 24D. In the final experiment, lighting schedules were applied during the brooding period from day 0 to 4 after hatching and leg bone develop­ment was measured at day 4 post hatch. 24L led to increased leg bone dimensions, but lower developmental stability of the leg bones than a lighting schedule with 1 or 6 hours of darkness after every 2 hours of light.

    The overall findings of this thesis suggest that continuous light during incubation and in the brooding period had a detrimental effect on embryonic and early post hatch leg bone development and health. The involvement of endocrine factors was not clarified from the current results. Applying a light-dark rhythm during incubation may improve embryonic leg bone development and leg health at slaughter age compared to continuous light and continuous darkness, without affecting post hatch production performance, but it appears that the dark period should last longer than 8 hours per day for optimal leg bone development.

    Temperature during the last week of incubation. III. Effects on chicken embryo physiology
    Maatjens, C.M. ; Roovert-Reijrink, I.A.M. van; Engel, B. ; Pol, C.W. van der; Kemp, B. ; Brand, H. van den - \ 2017
    Poultry Science 96 (2017)5. - ISSN 0032-5791 - p. 1451 - 1458.
    temperature - incubation - chicken embryo physiology - hepatic glycogen - temperature - incubation - chicken embryo physiology - hepatic glycogen
    We investigated effects of eggshell temperature (EST) of 35.6, 36.7, 37.8, or 38.9°C applied from d of incubation (E) 15, E17, or E19 onward on chicken embryo physiology. A total of 2,850 first-grade eggs of a 43-week-old Ross 308 broiler breeder flock were incubated at an EST of 37.8°C until E15. From E15, E17, or E19 onward, eggs were incubated at an EST of 35.6, 36.7, 37.8, or 38.9°C. Plasma glucose, uric acid, and lactate concentrations, and hepatic glycogen amount and concentration were measured at E15, E17, E19, internal pipping (IP), external pipping (EP), and hatch.
    An EST of 38.9°C applied from E15 onward decreased the amount of hepatic glycogen from E19 to IP and resulted in a lower glycogen amount at IP compared to all other EST. At EP, when oxygen (O2) becomes largely available, an EST of 38.9°C resulted in a higher glycogen amount and concentration compared to IP, which suggests that plasma glucose between IP and EP might be used for building up hepatic glycogen reserves. However, hepatic glycogen levels remained considerably lower at IP, EP, and hatch at an EST of 38.9°C, compared to an EST of 35.6 and 36.7°C.
    Opposite to an EST of 38.9°C, from IP onward, an EST of 35.6°C resulted in a higher glycogen amount and concentration compared to all other EST, which might be caused by the higher O2 availability relative to the lower metabolic rate, which provided time to build up glycogen stores from excessive glucose. A higher availability of hepatic glycogen might contribute to an improved physiological status of the broiler chicken embryo toward hatch. Hepatic gluconeogenesis is crucial for developing embryos, as glucose is the major energy source from IP until hatch. At hatch, no effect of EST was found for glucose, uric acid, or lactate.
    Results of this study emphasize that EST of 35.6 and 36.7°C from E15 onward appear to be beneficial for chicken embryo physiology.
    Effects of temperature and CO2 during late incubation on broiler chicken development
    Maatjens, C.M. - \ 2016
    Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; I.A.M. van Roovert-Reijrink. - Wageningen : Wageningen University - ISBN 9789462578258 - 196
    broilers - embryonic development - temperature - carbon dioxide - incubation - animal physiology - broiler performance - artificial hatching - hatcheries - poultry farming - vleeskuikens - embryonale ontwikkeling - temperatuur - kooldioxide - broeden - dierfysiologie - vleeskuikenresultaten - kunstmatig bebroeden - broedinstallaties - pluimveehouderij

    Incubation conditions need to be adjusted to meet embryonic requirements to obtain optimal chick quality and hatchability. Eggshell temperature (EST) can be used as a non- invasive method to determine embryo temperature. A high EST of 38.9°C during the second or third week of incubation negatively affects chicken embryo development and survival compared to a constant EST of 37.8°C during that period. These negative effects of high EST might be due to a dis-balance between metabolic rate and oxygen (O2) availability. However, effects of lowering EST, which might restore the balance between metabolic rate and O2 availability, are largely unknown. Besides EST, the carbon dioxide (CO2) concentration during late incubation also seems to affect embryo development and might even interact with EST. Based on the potential effects of (lower) EST during the last week of incubation and of CO2 during only the hatching phase, the following three aims are derived: 1, to investigate effects of EST during the last phase of the incubation process, with special attention for EST below the general accepted optimal EST of 37.8°C, 2, to examine from which day of the incubation process onward EST should be changed from 37.8°C, and 3, to investigate whether CO2 concentrations are interacting with EST during the hatcher phase.

    Time until hatch was longer when an EST of 35.6°C was applied during the last week of incubation, followed by 36.7, 37.8, and 38.9°C, which is probably caused by the lower metabolic rate at an EST below 37.8°C. Hatchability of fertile eggs was not affected at low EST, and EST did not affect time between internal pipping (IP) and hatch. An EST of 35.6 and 36.7°C, resulted in a higher yolk-free body mass (YFBM) at hatch compared to 37.8 and 38.9°C, and residual yolk weight was higher at hatch at 38.9°C compared to all other EST treatments. An EST of 35.6°C resulted in higher hepatic glycogen concentration and amount at IP and hatch compared to all other EST treatments. The proposed mechanism involved is that at lower EST, metabolic rate is reduced, which prevents the embryo from O2 limitation and ensures that fatty acid oxidation from the yolk can be maintained, resulting in energy production to be invested in growth and development. At an EST of 38.9°C, metabolic rate is high, resulting in a relative O2 shortage for the embryo. Consequently, lipid oxidation is reduced, which forces the embryo to switch to alternative energy sources, such as glycogen. Because glycogen storage is very limited in the egg and embryo, alternative energy sources such as amino acids obtained from muscles might be used. A clear interaction between EST and start day of treatment was found for relative heart weight. Relative heart weight was higher at an EST of 35.6°C and decreased with increase in EST. The differences among EST became larger when the EST treatment started earlier.

    Effects of CO2 on embryo physiology, embryonic organ development, and chick quality were marginal. EST interacted with CO2 mainly before IP, but effects were minor at hatch. Interactions between EST and CO2 were found at an EST of 36.7 and 37.8°C, but remained absent at an EST of 38.9°C, which might indicate that physiological systems are already challenged due to the higher metabolic rate, which limits the capacity to cope with high CO2 of the embryo.

    No effect of start day of treatment was indicated for embryonic organ development and chick quality found at hatch, which suggests that EST affected these parameters only in the last phase of incubation, e.g. from E19 onward. However, first week post-hatch performance was affected by start day of treatment. The beneficial effects of a lower EST of 35.6 and 36.7°C applied during the last week of incubation found at hatch, might contribute to an enhanced development during the first week post-hatch as body weight, carcass weight, and gain to feed ratio were increased.

    In conclusion, results of this thesis show that an EST below 37.8°C during late incubation is beneficial for embryo development, organ growth during incubation, and growth performance during the first week post-hatch. In addition, start day of treatment did not affect chick quality and organ growth, except heart weight, at hatch, which implies that effects of EST occur during the hatching phase, e.g. from E19 onward. Although, an effect of start day of treatment was found on first week post-hatch performance, it remains to be investigated whether an EST below 37.8°C leads to improved later life quality characteristics.

    Effects of floor eggs on hatchability and later life performance in broiler chickens
    Brand, H. Van Den; Sosef, M.P. ; Lourens, A. ; Harn, J. Van - \ 2016
    Poultry Science 95 (2016)5. - ISSN 0032-5791 - p. 1025 - 1032.
    broiler - floor eggs - footpad dermatitis - hatchability - incubation

    Two experiments were conducted in which effects of floor eggs, washed floor eggs, and clean nest eggs were investigated on incubation characteristics and performance in later life of broiler chickens. In both experiments, a young and an older breeder flock were used in a 3 × 2 factorial design during incubation. In the second experiment, male and female chickens were reared separately until d 35 of age in floor pens. During this grow out trial, an extra group was created in which chickens obtained from clean nest eggs were mixed with chickens obtained from floor eggs, meaning that grow out period was set up as a 4 × 2 × 2 factorial design with 4 egg types, 2 breeder ages, and 2 sexes. In both experiments, fertility and hatchability of fertile eggs were lower in floor and washed eggs than in clean nest eggs (hatchability: experiment 1: 74.4 vs. 70.6 vs. 92.6% for floor eggs, washed floor eggs and clean nest eggs, respectively, P <0.001; experiment 2: 78.3 vs. 81.7 vs. 90.2%, respectively, P <0.001). In experiment 2, BW at d 0 of chickens obtained from clean nest eggs was higher than that of chickens from floor eggs and washed floor eggs (41.5 vs. 40.4 and 40.3 g, respectively; P <0.001). This difference disappeared during the grow out period and was absent at slaughter age at d 35 of age. Feed intake (FI), feed conversion ratio (FCR), and mortality during the grow out period were not affected by egg type. Incidence and severity of hock burns and footpad dermatitis were not affected by egg type or breeder age. Litter friability at d 35 of age tended to be lower in pens with chickens obtained from washed floor eggs compared to clean nest eggs. We conclude that incubation of floor eggs or washed floor eggs resulted in lower fertility and hatchability compared to clean nest eggs, but that performance during the grow out period was not affected.

    Temperature during the last week of incubation. I. Effects on hatching pattern and broiler chicken embryonic organ development
    Maatjens, C.M. ; Roovert-Reijrink, I.A.M. van; Engel, B. ; Pol, C.W. van der; Kemp, B. ; Brand, H. van den - \ 2016
    Poultry Science 95 (2016)4. - ISSN 0032-5791 - p. 956 - 965.
    temperature - incubation - embryonic organ development
    We investigated the effects of an eggshell temperature (EST) of 35.6, 36.7, 37.8, and 38.9°C applied from d of incubation (E) 15, E17, and E19 on hatching pattern and embryonic organ development. A total of 2,850 first-grade eggs of a 43-week-old Ross 308 broiler breeder flock were incubated at an EST of 37.8°C until E15. From E15, E17, or E19 onward, eggs were incubated at an EST of 35.6, 36.7, 37.8, or 38.9°C. Moment of internal pipping (IP), external pipping (EP), and hatch was determined, and organ development was measured at E15, E17, E19, IP, EP, and hatch.

    A lower EST extended incubation duration compared to a higher EST. The lower incubation duration was mainly caused by the extended time until IP, whereas time between IP and hatch hardly varied between treatments.

    Relative heart weight was affected by EST already from 2 d after the start of EST treatment on E15, and effects became more pronounced at longer exposure time to various EST treatments. At hatch, the largest difference in relative heart weight was found between an EST of 35.6 and 38.9°C started at E15 (Δ = 64.4%). From E17 onward, EST affected yolk-free body mass (YFBM) and relative stomach weight, where a lower EST resulted in a lower YFBM and relative stomach weight before IP and a higher YFBM and relative stomach weight after IP. From E19 onward, a lower EST resulted in a higher relative liver and spleen weight regardless of start time of treatment. Yolk weight and relative intestine weight were not affected by EST before and at E19, but a higher EST resulted in a higher yolk weight and lower relative intestine weight from IP onward.

    Based on the higher YFBM and higher relative organ growth found at hatch, we concluded that an EST lower than 37.8°C from E15 onward appears to be beneficial for optimal embryo development.
    Differences in egg nutrient availability, development, and nutrient metabolism of broiler and layer embryos
    Nangsuay, A. ; Molenaar, R. ; Meijerhof, R. ; Anker, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2015
    Poultry Science 94 (2015)3. - ISSN 0032-5791 - p. 415 - 423.
    heat-production - eggshell temperature - chicken embryos - oxygen concentration - protein-turnover - lipid-metabolism - incubation - growth - glycogen - energy
    Selection for production traits of broilers and layers leads to physiological differences, which may already be present during incubation. This study aimed to investigate the influence of strain (broiler vs layer) on egg nutrient availability, embryonic development and nutrient metabolism. A total of 480 eggs with an egg weight range of 62.0 to 64.0 g from Lohmann Brown Lite and Ross 308 breeder flocks of 41 or 42 weeks of age were selected in two batches of 120 eggs per batch per strain. For each batch, 30 eggs per strain were used to determine egg composition, including nutrient and energy content, and 90 eggs per strain were separately incubated in one of two climate respiration chambers at an eggshell temperature of 37.8°C. The results showed that broiler eggs had a higher ratio of yolk: albumen with 2.41 g more yolk and 1.48 g less albumen than layers. The yolk energy content of broiler eggs was 46.32 kJ higher than that of layer eggs, whereas total energy content of broiler eggs was 47.85 kJ higher compared to layer eggs. Yolk-free body mass at incubation day 16 and chick weight and length at hatch were higher in broilers compared to layers. Respiration quotient of broiler embryos was higher than layer embryos during incubation day 8 to incubation day 10. A 0.24 g lower residual yolk at the hatch of broiler embryos than for the layer embryos indicated that broiler embryos used more yolk and had a higher energy utilization and energy deposition in yolk-free body mass. Heat production of broiler embryos was higher than that of layer embryos from incubation day 12 to incubation day 18, but efficiency of converting egg energy used by embryos to form yolk-free body mass was similar. In conclusion, broiler and layer embryos have different embryonic development patterns, which affect energy utilization and embryonic heat production. However, the embryos are equal in efficiency of converting the energy used to yolk-free body mass.
    Are antimicrobial defences in bird eggs related to climatic conditions associated with risk of trans-shell microbial infection?
    Horrocks, N.P.C. ; Hine, K. ; Hegemann, A. ; Ndithia, H.K. ; Shobrak, M. ; Ostrowski, S. ; Williams, J.B. ; Matson, K.D. ; Tieleman, B.I. - \ 2014
    Frontiers in Zoology 11 (2014). - ISSN 1742-9994 - 10 p.
    bacterial loads - life-history - maternal exposure - barn swallow - avian egg - incubation - diversity - eggshells - temperature - lysozyme
    Introduction All bird eggs are exposed to microbes in the environment, which if transmitted to the developing embryo, could cause hatching failure. However, the risk of trans-shell infection varies with environmental conditions and is higher for eggs laid in wetter environments. This might relate to generally higher microbial abundances and diversity in more humid environments, including on the surface of eggshells, as well as the need for moisture to facilitate microbial penetration of the eggshell. To protect against microbial infection, the albumen of avian eggs contains antimicrobial proteins, including lysozyme and ovotransferrin. We tested whether lysozyme and ovotransferrin activities varied in eggs of larks (Alaudidae) living along an arid-mesic gradient of environmental aridity, which we used as a proxy for risk of trans-shell infection. Results Contrary to expectations, lysozyme activity was highest in eggs from hotter, more arid locations, where we predicted the risk of trans-shell infection would be lower. Ovotransferrin concentrations did not vary with climatic factors. Temperature was a much better predictor of antimicrobial protein activity than precipitation, a result inconsistent with studies stressing the importance of moisture for trans-shell infection. Conclusions Our study raises interesting questions about the links between temperature and lysozyme activity in eggs, but we find no support for the hypothesis that antimicrobial protein deposition is higher in eggs laid in wetter environments.
    Effect van gewassen en ongewassen grondeieren op broeduitkomsten en vleeskuikenprestaties
    Harn, J. van; Sosef, M.S.M. ; Lourens, A. - \ 2014
    Wageningen : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 798) - 44
    pluimveehouderij - vleeskuikens - dierenwelzijn - grondeieren - pluimvee - dierlijke productie - broeden - vleeskuikenresultaten - eierproductie - broedeieren - poultry farming - broilers - animal welfare - floor eggs - poultry - animal production - incubation - broiler performance - egg production - hatching eggs
    This report describes the results of a research in which effects of the incubation of washed and unwashed floor eggs on incubation and performance results of the offspring (broilers) was studied.
    The forgotten half of scientific thinking
    Scheffer, M. - \ 2014
    Proceedings of the National Academy of Sciences of the United States of America 111 (2014)17. - ISSN 0027-8424 - p. 6119 - 6119.
    incubation
    Although thinking is the core business of scientists, we rarely ponder how it thrives best; this is ironic, as there is abundant scientific insight to draw upon. For example, it is now known that thinking has two complementary modes: roughly, association versus reasoning (1). We systematically underestimate the role of the first (1), and the way our institutions, meetings, and teaching are organized heavily reflects this imbalance. By contrast, many of the greatest scientists systematically nurtured a balanced dual-thinking process. We should follow their example and reform scientific practice and education to catalyze the unusual combinations of knowledge that often turn out to have the highest impact (2).
    Broedsucces van kustbroedvogels in de Waddenzee in 2009 en 2010
    Kleunen, A. van; Koffijberg, K. ; Oosterbeek, K. ; Nienhuis, J. ; Jong, M.L. de; Smit, C.J. ; Roomen, M. ; Boer, P. - \ 2012
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 346) - 55
    broedvogels - broeden - monitoring - waddenzee - kustgebieden - noord-nederland - breeding birds - incubation - monitoring - wadden sea - coastal areas - north netherlands
    Sinds 2005 worden in de Waddenzee jaarlijks gegevens verzameld over het broedsucces van een aantal karakteristieke kustbroedvogels. Hiervoor worden tien vogelsoorten gevolgd die representatief worden geacht voor specifieke habitats en voedselgroepen. Het reproductiemeetnet Waddenzee wordt uitgevoerd als een ‘early warning systeem’ om het reproducerend vermogen van de vogelpopulaties in de Waddenzee te volgen en de achterliggende processen van populatieveranderingen te doorgronden en fungeert als een wezenlijke aanvulling op de monitoring van aantallen en aantalsveranderingen. Het onderzoek wordt uitgevoerd in het kader van trilaterale afspraken met Duitsland en Denemarken (TMAP). De resultaten uit 2009 en 2010 laten zien dat veel soorten kustbroedvogels op dit moment een relatief laag broedsucces hebben. Vooral voor Eider, Scholekster, Kluut, Visdief en Noordse Stern geldt dat er te weinig jongen vliegvlug worden om de populatie op peil te houden. De slechte broedresultaten worden veroorzaakt door verschillende factoren. Eén daarvan is overstromingen als gevolg van hoog water gedurende het broedseizoen. Ook worden in de nestfase veel broedvogels slachtoffer van predatie van legsels, met name door Vos en Bruine Rat. Daarnaast speelt een te geringe voedselbeschikbaarheid een rol
    Comparative analysis as a management tool for broiler breeder farms: simulated individual farm analysis (IFAS)
    Yassin, H. ; Velthuis, A.G.J. ; Giesen, G.W.J. ; Oude Lansink, A.G.J.M. - \ 2012
    Poultry Science 91 (2012)3. - ISSN 0032-5791 - p. 744 - 757.
    chick quality - body-weight - economic-evaluation - egg quality - hatchability - performance - nutrition - feed - age - incubation
    The objective of this study was to develop a management information system to evaluate the tactical management of a breeder flock using individual farm analysis with a deterministic simulation model (IFAS). Individual farm analysis is a method that evaluates the performance of individual farms by comparing them with standards. In the first step of IFAS, a farm accounting system is used to compare performance indicators of a flock with the same performance indicators of the average of a group of flocks that produced in the same time period. In the next step, a deterministic simulation model is used to determine the factors causing the traced deviations in performances. Then, relevant deviations are determined based on the economic and statistical importance of each traced deviation. Finally, the deviations are identified by relevance to give farmers an indication of their strong and weak management practices.
    Significance of chick quality score in broiler production
    Ven, L.J.F. van de; Wagenberg, A.V. van; Uitdehaag, K.A. ; Groot Koerkamp, P.W.G. ; Kemp, B. ; Brand, H. van den - \ 2012
    Animal 6 (2012)10. - ISSN 1751-7311 - p. 1677 - 1683.
    egg storage time - embryonic-development - posthatch growth - hatchability - performance - incubation - weight - age - temperature - parameters
    The quality of day old chicks is crucial for profitable broiler production, but a difficult trait to define. In research, both qualitative and quantitative measures are used with variable predictive value for subsequent performance. In hatchery practice, chick quality is judged on a binomial scale, as chicks are divided into first grade (Q1-saleable) and second grade (Q2) chicks right after hatch. Incidences and reasons for classifying chicks as Q2, and potential of these chicks for survival and post-hatch performance have hardly been investigated, but may provide information for flock performance. We conducted an experiment to investigate (1) the quality of a broiler flock and the relation with post-hatch flock performance based on a qualitative score (Pasgar©score) of Q1 chicks and based on the incidence of Q2 chicks and (2) the reasons for classifying chicks as Q2, and the potential of these chicks for survival and post-hatch growth. The performance was followed of Q1 and Q2 chicks obtained from two breeder flocks that hatched in two different hatching systems (a traditional hatcher or a combined hatching and brooding system, named Patio). Eggs were incubated until embryo day 18, when they were transferred to one of the two hatching systems. At embryo day 21/post-hatch day 0, all chicks from the hatcher (including Q2 chicks) were brought to Patio, where the hatchery manager marked the Q2 chicks from both flocks and hatching systems and registered apparent reasons for classifying these chicks as Q2. Chick quality was assessed of 100 Q1 chicks from each flock and hatching system. Weights of all chicks were determined at days 0, 7, 21 and 42. There were no correlations between mean Pasgar©score and post-hatch growth or mortality, and suboptimal navel quality was the only quality trait associated with lower post-hatch growth. Growth was clearly affected by breeder flock and hatching system, which could not be linked to mean Pasgar©score or incidence of Q2 chicks. Q2 chicks showed lower post-hatch growth compared to Q1 chicks but effects on flock performance at slaughter weight were limited because early mortality in Q2 chicks was high (62.50% at 7 days). We concluded that chick qualitative scores and the incidence of Q2 chicks may be informative for the quality of incubation, but are not predictive for post-hatch flock performance. Culling Q2 chicks after hatch is well-founded in terms of both animal welfare and profitability.
    Eggs in the Freezer: energetic Consequences of Nest Site and Nest Design in Arctic Breeding Shorebirds
    Tulp, I.Y.M. ; Schekkerman, H. ; Leeuw, J.J. de - \ 2012
    PLoS ONE 7 (2012)6. - ISSN 1932-6203 - 9 p.
    mating system - heat-loss - incubation - predation - expenditure - insulation - sandpipers - selection - clutch - tundra
    Birds construct nests for several reasons. For species that breed in the Arctic, the insulative properties of nests are very important. Incubation is costly there and due to an increasing surface to volume ratio, more so in smaller species. Small species are therefore more likely to place their nests in thermally favourable microhabitats and/or to invest more in nest insulation than large species. To test this hypothesis, we examined characteristics of nests of six Arctic breeding shorebird species. All species chose thermally favourable nesting sites in a higher proportion than expected on the basis of habitat availability. Site choice did not differ between species. Depth to frozen ground, measured near the nests, decreased in the course of the season at similar non-species-specific speeds, but this depth increased with species size. Nest cup depth and nest scrape depth (nest cup without the lining) were unrelated to body mass (we applied an exponent of 0.73, to account for metabolic activity of the differently sized species). Cup depth divided by diameter2 was used as a measure of nest cup shape. Small species had narrow and deep nests, while large species had wide shallow nests. The thickness of nest lining varied between 0.1 cm and 7.6 cm, and decreased significantly with body mass. We reconstruct the combined effect of different nest properties on the egg cooling coefficient using previously published quantitative relationships. The predicted effect of nest cup depth and lining depth on heat loss to the frozen ground did not correlate with body mass, but the sheltering effect of nest cup diameter against wind and the effects of lining material on the cooling coefficient increased with body mass. Our results suggest that small arctic shorebirds invest more in the insulation of their nests than large species
    A reliable method for sexing unincubated bird eggs for studying primary sex ratio
    Aslam, M.A. ; Hulst, M.M. ; Hoving-Bolink, A.H. ; Wit, A.A.C. de; Smits, M.A. ; Woelders, H. - \ 2012
    Molecular Ecology Resources 12 (2012)3. - ISSN 1755-098X - p. 421 - 427.
    gallus-gallus-domesticus - chicken eggs - manipulation - fowl - corticosterone - identification - contamination - spermatozoa - incubation - investment
    In birds, offspring sex ratio manipulation by mothers is now well established with potentially important consequences for evolution and animal breeding. In most studies on primary sex ratio of birds, eggs are sexed after incubation by the use of PCR methods targeted to the sex-linked CHD1 genes. Sexing of unincubated eggs would be preferred, but as fertile and infertile blastodiscs cannot be distinguished macroscopically, errors could arise from PCR amplifications of parental DNA associated with the vitelline membrane of infertile eggs. In this study, we stained blastodiscs without the vitelline membrane with Hoechst 33342. This allowed unequivocal distinction between fertile and infertile blastodiscs. Fertile blastodiscs contained thousands of fluorescent nuclei, whereas no nuclei were seen in infertile eggs. In addition, after nucleic acid analysis, fertile blastodiscs yielded much stronger chromosomal DNA and CHD1-targeted PCR bands on agarose gels compared with infertile blastodiscs. These findings indicate that fertile blastodiscs contain much more embryonic DNA than parental DNA, allowing reliable sexing of the fertile eggs. The differences between fertile and infertile blastodiscs in chromosomal DNA and CHD1 PCR banding intensities alone could also be used to distinguish fertile from infertile eggs without using Hoechst staining. We conclude that identifying fertile blastodiscs either by Hoechst staining or by analyzing the yield of chromosomal DNA and CHD1-PCR products, combined with CHD1-targeted PCR amplification, presents an easy and reliable method to sex unincubated eggs.
    Adaptive capacity of rearing hens : effects of early life conditions
    Walstra, I. - \ 2011
    Wageningen University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; Jan ten Napel. - [S.l.] : S.n. - ISBN 9789461731265 - 147
    hennen - opfoktechnieken - broeden - uitbroeden - embryogenese - experimentele infectie - warmtestress - immuniteitsreactie - immunologie - adaptatiefysiologie - hens - rearing techniques - incubation - hatching - embryogenesis - experimental infection - heat stress - immune response - immunology - adaptation physiology

    The traditional strategy to deal with pathogens in the layer industry is based on monitoring and control methods, primarily aimed at minimizing the risk of infection with the pathogen. The aim of this thesis was to investigate whether the adaptive capacity of layers could be influenced by early life conditions as they may occur in layer practice, as an alternative strategy for improving layer health and disease resistance. The first study investigated whether suboptimal versus optimal incubation, hatch and early rearing conditions could influence the adaptive capacity during infectious challenges with Eimeria and Infectious Bronchitis (IB). The second study investigated effects of prenatal high temperature manipulation on postnatal temperature preference and adaptive response of layers to heat stress. The third study investigated effects of suboptimal and optimal incubation temperature on the adaptive response to Eimeria under normal circumstances or following exposure to a high (35oC) environmental temperature. The fourth study investigated effects of feed provision immediately after hatch (early feeding) and suppression of gram negative intestinal bacteria (by use of the antibiotic Colistin) for 21 d post hatch on microbial composition of the intestines, layer development and response to a mix challenge with lipopolysaccharide (LPS) and humane serum albumin (HuSA). Finally, effects of early feeding and Colistin treatment on organ weights and response to an infectious challenge with Eimeria were investigated. Results demonstrated that optimized incubation, hatch and rearing resulted in a better adaptive response to Eimeria and IB, as was shown by a higher feed intake and reduced weight loss. Optimal incubation as a single early life condition also had a positive influence on the adaptive response of layers toEimeria, as demonstrated by tendencies to higher feed intake and BW gain, less duodenal lesions and a lower oocyst production. Early feeding resulted in higher body and organ weights, a changed microbiota composition in the intestines, and a changed response to E. acervulina and LPS/HuSA. Colistin treatment resulted in a changed microbiota composition of the intestines and a changed response to E. acervulina and LPS/HuSA. These results confirmed the hypothesis that early life conditions can be used to influence the adaptive capacity to infectious challenges. In conclusion, improving the adaptive capacity with the use of particular early life conditions may be the first step towards an alternative method to maintain or improve layer health and disease resistance.

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