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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Bioconversion efficiencies, greenhouse gas and ammonia emissions during black soldier fly rearing – A mass balance approach
    Parodi, Alejandro ; Boer, Imke J.M. de; Gerrits, Walter J.J. ; Loon, Joop J.A. van; Heetkamp, Marcel J.W. ; Schelt, Jeroen van; Bolhuis, J.E. ; Zanten, Hannah H.E. van - \ 2020
    Journal of Cleaner Production 271 (2020). - ISSN 0959-6526
    Ammonia - Bioconversion - Emissions - GHG - Hermetia illucens - Nitrogen

    Black soldier fly larvae (BSFL) are acknowledged for their potential to upcycle waste biomass into animal feed, human food or biofuels. To ensure sustainable BSFL rearing, insight into nutrient bioconversion efficiencies and nutrient losses via gaseous emissions is key. This study used a mass balance approach to quantify nutrient bioconversion efficiencies (i.e., carbon, energy, nitrogen, phosphorus and potassium) and gaseous emissions (i.e., greenhouse gasses and ammonia) of BSFL reared on a substrate used in industrial production. On this substrate, bioconversion efficiencies ranged from 14% (potassium) to 38% (nitrogen). The proportion of dietary inputs found in the residues ranged from 55% (energy) to 86% (potassium), while the proportion of dietary inputs lost via gaseous emissions ranged from 1% (nitrogen) to 24% (carbon). Direct emissions of methane and nitrous oxide during rearing were 16.8 ± 8.6 g CO2-equivalents per kg of dry BSFL biomass. Even though ammonia emissions were minimal, these could have been avoided if larvae would have been harvested before the CO2 peak was reached. Our results provide the first complete mass balance and comprehensive quantification of BSF larval metabolism and GHG emissions, required to assess and improve the environmental sustainability of BSFL production systems.

    Data and R code: Bioconversion efficiencies, greenhouse gas and ammonia emissions during black soldier fly rearing – a mass balance approach
    Parodi, Alejandro ; Boer, Imke de; Gerrits, Walter ; Loon, Joop van; Heetkamp, Marcel ; Schelt, Jeroen van; Bolhuis, Liesbeth ; Zanten, Hannah van - \ 2020
    Wageningen University & Research
    ammonia - bioconversion - emissions - GHG - Hermetia illucens - nitrogen
    Contains data and R code for analysis and visualizations of the study Bioconversion efficiencies, greenhouse gas and ammonia emissions during black soldier fly rearing.
    Nutrient flows and associated gaseous emissions of the production of black soldier flies
    Parodi, Alejandro ; Boer, I.J.M. de; Gerrits, W.J.J. ; Loon, J.J.A. van; Heetkamp, M.J.W. ; Schelt, Jeroen van; Bolhuis, J.E. ; Zanten, H.H.E. van - \ 2020
    In: Wias Annual Conference 2020. - WIAS - p. 51 - 51.
    Black soldier fly larvae (BSFL) production is on the rise. BSFL can grow on a wide range of organic streams making them ideal candidates to turn organic streams into biomass that can be upcycled in the food system, as either animal feed or human food. Even though previous studies have reported the efficiency with which BSFL convert dry matter and nitrogen in different organic streams into larval biomass, little is known about when and how nutrient losses occur. Here we aimed to quantify the flows of dry matter, carbon, energy,nitrogen, phosphorus and potassium between a diet currently used for large-scale BSFL production, and the larval biomass, residues, and gaseous emissions during BSFL rearing in a climate respiration chamber. Larval conversion efficiencies ranged from 14% (potassium)to 38% (nitrogen). The proportion of dietary inputs found in the residues ranged from53% (energy) to 87% (potassium), while the proportion of dietary inputs lost via gaseous emissions ranged from 0.7% (nitrogen) to 23% (carbon). We found high concentrations of starch in the residues, indicating that BSFL did not use all the feed provided. Correcting carbon and energy efficiencies for unconsumed starch increased BSFL carbon and energy conversion efficiencies slightly. Even though gaseous nitrogen losses were minimal, ammonia-nitrogen was produced with a defined temporal pattern, starting on the fifth rearing day right after the peak of carbon dioxide was reached. Direct emissions of methane and nitrous oxide during the rearing were 14.9 ± 2.3 g CO2-equivalents per kg of dry BSFL. Our results are relevant for the improvement of BSFL conversion efficiencies and for understanding the dynamics of gaseous emissions during BSFL rearing.
    Nutrient flows and associated gaseous emissions of the production of black soldier flies
    Parodi, Alejandro ; Boer, I.J.M. de; Gerrits, W.J.J. ; Loon, J.J.A. van; Heetkamp, M.J.W. ; Schelt, J. van; Bolhuis, J.E. ; Zanten, H.H.E. van - \ 2020
    In: WIAS Annual Conference 2020 WIAS - p. 51 - 51.
    Black soldier fly larvae (BSFL) production is on the rise. BSFL can grow on a wide range oforganic streams making them ideal candidates to turn organic streams into biomass thatcan be upcycled in the food system, as either animal feed or human food. Even thoughprevious studies have reported the efficiency with which BSFL convert dry matter and nitrogenin different organic streams into larval biomass, little is known about when and hownutrient losses occur. Here we aimed to quantify the flows of dry matter, carbon, energy,nitrogen, phosphorus and potassium between a diet currently used for large-scale BSFLproduction, and the larval biomass, residues, and gaseous emissions during BSFL rearingin a climate respiration chamber. Larval conversion efficiencies ranged from 14% (potassium)to 38% (nitrogen). The proportion of dietary inputs found in the residues ranged from53% (energy) to 87% (potassium), while the proportion of dietary inputs lost via gaseous emissions ranged from 0.7% (nitrogen) to 23% (carbon). We found high concentrations of starch in the residues, indicating that BSFL did not use all the feed provided. Correcting carbon and energy efficiencies for unconsumed starch increased BSFL carbon and energy conversion efficiencies slightly. Even though gaseous nitrogen losses were minimal, ammonia-nitrogen was produced with a defined temporal pattern, starting on the fifth rearing day right after the peak of carbon dioxide was reached. Direct emissions of methane and nitrous oxide during the rearing were 14.9 ± 2.3 g CO2-equivalents per kg of dry BSFL. Our results are relevant for the improvement of BSFL conversion efficiencies and for understanding the dynamics of gaseous emissions during BSFL rearing.
    Application 3: Heat stress
    Campos, Paulo ; Heetkamp, Marcel - \ 2019
    Measurement of heat production and energy balance under different climatic conditions (temperature, relative humidity)
    Design of calorimeters
    Heetkamp, Marcel ; Labussiere, Etienne ; Reis e Silva, Ricardo - \ 2019
    Background and general principles
    Diet density during the first week of life: Effects on growth performance, digestive organ weight, and nutrient digestion of broiler chickens
    Lamot, D.M. ; Sapkota, D. ; Wijtten, P.J.A. ; Anker-Hensen, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2019
    Poultry Science 98 (2019)2. - ISSN 0032-5791 - p. 789 - 795.
    The current study aimed to investigate whether diet density affects growth performance and nutrient digestion during the first wk after hatch and digestive organ weight at 7 d of age. Effects were studied using a dose-response design consisting of 5 dietary fat levels (3.5, 7.0, 10.5, 14.0, and 17.5%). The dietary fat level was increased through soybean oil inclusion. Amino acids, minerals, and the premix were increased at the same ratio as dietary fat. Consequently, diets were kept neither isocaloric nor isonitrogenous. Broiler chickens were weighed on d 0 and d 7 after hatch, whereas feed intake was measured daily. Excreta produced from d 0 to d 7 was collected at d 7. Dietary dry matter and nitrogen metabolizability, as well as fat digestibility were calculated as an average over 7 days. Broiler chickens were sampled at d 7 to determine carcass yield, breast meat yield, and organ weights. Average daily gain (P = 0.047) and average daily feed intake (P < 0.001) decreased linearly as diet density increased, while gain to feed ratio increased linearly (P < 0.001). An increased diet density resulted in a linear decrease of crop, liver, and pancreas weight relative to body weight (BW; P < 0.05). Duodenum, jejunum, ileum, and cecum length (expressed as cm/kg of BW) and empty weight (as % of BW) increased linearly with increased diet density (P < 0.05). Dietary dry matter metabolizability decreased linearly as diet density increased (P < 0.001), whereas fat digestibility and nitrogen metabolizability were not affected (P > 0.05). In conclusion, one-week-old broiler chickens respond to increased diet densities by increasing intestinal weight and length, while decreasing liver and pancreas weight. This may be an adaptive response to cope with an increased nutrient concentration in the diet.
    Both the rooster line and incubation temperature affect embryonic metabolism and hatchling quality in laying hen crossbreds
    Brand, H. van den; Kraats, S.J.F. van de; Sözcü, Arda ; Jöerissen, R. ; Heetkamp, M.J.W. ; Anker-Hensen, I. van den; Ooms, M. ; Kemp, B. - \ 2019
    Poultry Science 98 (2019)6. - ISSN 0032-5791 - p. 2632 - 2640.
    Effects of 3 eggshell temperatures (EST; 36.7. 37.8, and 38.9°C) in 2 genetic laying hen crossbreds (AB and BB; same hen line, different rooster line) on embryonic metabolism and hatchling quality were investigated. EST were applied from day 14.5 of incubation (E14.5) until hatching. The experiment consisted of 6 consecutive batches with eggs weighing between 59 and 61 g. Heat production was determined continuously from E14.5 onward. In fresh eggs, yolk weight tended to be higher (Δ = 0.28 g; P = 0.08) in the AB crossbred than in the BB crossbred. At E14.5 and E18.5, yolk-free body mass (YFBM) and residual yolk (RY) weight did not differ between genetic crossbred and EST. Hatching time after the start of incubation was not affected by genetic crossbred, but was longer in the 36.7°C (517 h) than in the 38.9°C (505 h), with 37.8°C in between (506 h). At 6 h after hatching, no differences between crossbreds were found for chicken quality parameters, such as chicken weight, chicken length, RY, YFBM, and organ weights, but heart weight was higher in the 36.7°C EST than in the other 2 EST (Δ = 0.24 to 0.30% of YFBM, P = 0.005). Intestinal weight was higher at 36.7°C EST than at 38.9°C EST (Δ = 0.79% of YFBM; P = 0.02), with 37.8°C EST in between. Heat production between E14.5 and E18.5 was higher in the AB crossbred than in the BB crossbred (Δ = 2.61%, P < 0.001) and regardless of crossbred higher at an EST of 38.9°C than at other 2 EST (Δ = 3.59% on average; P < 0.001). Hatchling quality determined at pulling (E21.5) was not affected by EST, but AB chickens were lighter (Δ = 0.46 g; P = 0.03), had less red hocks (Δ = 0.03; P = 0.02), more red beaks (Δ = 0.10; P < 0.001), and a higher (worse) navel score (Δ = 0.11; P < 0.001) than BB chickens. It can be concluded that not only incubation temperature, but also the rooster line appears to play a role in layer crossbred embryo metabolism and hatchling quality.
    Both the rooster and incubation temperature affect embryonic metabolism and day-old chicken quality in laying hens
    Brand, H. van den; Kraats, Sabrina van de; Sözcü, Arda ; Jöerissen, R. ; Heetkamp, M.J.W. ; Anker-Hensen, I. van den; Ooms, M. ; Kemp, B. - \ 2018
    In: The XVth European Poultry Conference (EPC). - Zagreb, Croatia : Croatian Branch of the World's Poultry Science Association - ISBN 9789082915709 - p. 128 - 128.
    chicken quality - embryonic heat production - incubation temperature - laying hens - rooster
    During incubation, the main factors driving embryonic metabolism and developmentare nutrient availability, oxygen availability and embryo temperature. Both nutrient andoxygen availability are expected to be particularly affected by the hen and thus the henis thought to majorly determining embryonic metabolism and day-old chicken quality.However, in wild birds it has been suggested that the rooster is of influence on offspringquality, directly or via affecting egg size and egg composition. In poultry, the role of therooster in embryonic development and metabolism is hardly investigated. In case therooster affects egg composition, this can mean that the incubation temperature needs to be adjusted to obtain optimal embryo temperature. The role of incubation temperatureon embryonic metabolism and development in the broiler chicken is extensivelyinvestigated, but much less information is available regarding laying hen chickens.The aim of the experiment was to investigate the role of the rooster and the incubationtemperature on laying hen embryonic development and chicken quality. Eggs of twogenetic crossbreds (AB and BB; 51 to 59 weeks of age) were used. Hens originated fromthe same breeder flock, were housed at the same farm, obtained the same managementand diet but were mated with a different rooster. In six consecutive batches, eggs ofboth crossbreds (59.0 to 61.0 gram) were incubated at an eggshell temperature (EST) of37.8oC during the first 14.5 days and at an EST of 36.7, 37.8 or 38.9oC from day 14.5 ofincubation onward. In all batches, eggs of both crossbreds were used, but EST differedamong batches. Egg composition was determined in fresh eggs, heat production wasdetermined between day 14.5 and 18.5 of incubation and day-old chicken quality wasdetermined at 6 hours after hatching or at pulling. Yolk weight tended to be higher(Δ=0.28 gram; P=0.08) in AB than in BB crossbreds, whereas other egg components didnot differ. Heat production between day 14.5 and 18.5 of incubation was higher in theAB than in the BB crossbred (Δ=2.61%; P<0.001). At pulling, AB chickens were lighter,had less red hocks, more red beaks and worse navel scores than BB chickens. An ESTof 36.7oC resulted in later hatching time, higher heart weight and higher intestineweight than an EST of 38.9oC. It can be concluded that both the rooster and incubationtemperature appears to affect embryonic metabolism and day-old chicken quality.
    Effects of breeder age and oxygen concentration during incubation on embryonic heat production and development, and post-hatch chick performance
    Molenaar, R. ; Nangsuay, A. ; Meijerhof, R. ; Anker-Hensen, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2017
    European Poultry Science 81 (2017). - ISSN 1612-9199 - p. 4 - 4.
    The interaction between carbon dioxide concentration and eggshell temperature during the second half of incubation in broiler chickens
    Brand, H. van den; Meijerhof, R. ; Heetkamp, M.J.W. ; Anker-Hensen, I. van den; Ooms, M. ; Kemp, B. - \ 2017
    European Poultry Science 81 (2017). - ISSN 1612-9199 - p. 23 - 23.
    Poultry - CO2 - eggshell - heat production - chicken quality
    Diet density during the first week of life: Effects on energy and nitrogen balance characteristics of broiler chickens
    Lamot, D.M. ; Sapkota, D. ; Wijtten, P.J.A. ; Anker-Hensen, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2017
    Poultry Science 96 (2017)7. - ISSN 0032-5791 - p. 2294 - 2300.
    broiler chickens - dietary fat - diet density - energy balance - indirect calorimetry
    This study aimed to determine effects of diet density on growth performance, energy balance, and nitrogen (N) balance characteristics of broiler chickens during the first wk of life. Effects of diet density were studied using a dose-response design consisting of 5 dietary fat levels (3.5, 7.0, 10.5, 14.0, and 17.5%). The relative difference in dietary energy level was used to increase amino acid levels, mineral levels, and the premix inclusion level at the same ratio. Chickens were housed in open-circuit climate respiration chambers from d 0 to 7 after hatch. Body weight was measured on d 0 and 7, whereas feed intake was determined daily. For calculation of energy balances, O2 and CO2 exchange were measured continuously and all excreta from d 0 to 7 was collected and analyzed at d 7. Average daily gain (ADG) and average daily feed intake (ADFI) decreased linearly (P = 0.047 and P < 0.001, respectively), whereas gain to feed ratio increased (P < 0.001) with increasing diet density. Gross energy (GE) intake and metabolizable energy (ME) intake were not affected by diet density, but the ratio between ME and GE intake decreased linearly with increasing diet density (P = 0.006). Fat, N, and GE efficiencies (expressed as gain per unit of nutrient intake), heat production, and respiratory exchange ratio (CO2 to O2 ratio) decreased linearly (P < 0.001) as diet density increased. Energy retention, N intake, and N retention were not affected by diet density. We conclude that a higher diet density in the first wk of life of broiler chickens did not affect protein and fat retention, whereas the ME to GE ratio decreased linearly with increased diet density. This suggests that diet density appears to affect digestibility rather than utilization of nutrients.
    Effects of breeder age, strain, and eggshell temperature on nutrient metabolism of broiler embryos
    Nangsuay, A. ; Meijerhof, R. ; Anker-Hensen, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2017
    Poultry Science 96 (2017)1. - ISSN 0032-5791 - p. 1891 - 1900.
    Breeder age and broiler strain influence the availability of nutrients and oxygen through yolk size and eggshell conductance, and the effects of these egg characteristics on nutrient metabolism might be influenced by eggshell temperature (EST). This study aims to determine effects of breeder age, strain, and EST on nutrient metabolism of embryos. A study was designed as a 2 × 2 × 2 factorial arrangement using four batches of in total 4,464 hatching eggs of 2 flock ages at 29 to 30 wk (young) and 54 to 55 wk (old) of Ross 308 and Cobb 500. EST of 37.8 (normal) or 38.9°C (high) was applied from incubation day 7 (E7) until hatching. Wet yolk weight was determined mainly by breeder age (P = 0.043). Energy content in yolk (P = 0.004) and albumen + yolk (P = 0.005) were higher in old flock eggs than in young flock eggs, but did not differ between broiler strains. Eggshell conductance was higher in Ross 308 eggs than in Cobb 500 eggs (P < 0.001). Old flock embryos used more energy (P = 0.046) and accumulated more energy into yolk free body mass (YFBM; P = 0.030) than young flock embryos, whereas heat production (HP), energy lost, and efficiency of converting energy used to YFBM (EYFB) did not differ. Ross 308 embryos used more energy (P = 0.006), had a higher energy lost (P = 0.010), and a higher HP between E15 to E18 (P < 0.05) than Cobb 500 embryos. Energy content in YFBM did not differ between strains and EYFB (P = 0.024) was lower in Ross 308 than in Cobb 500. High EST resulted in higher HP than low EST from E11 to E15 (P < 0.05), but not after E15. Amount of energy used (P = 0.006) and energy accumulated in the YFBM (P < 0.001) was lower for embryos incubated at an EST of 38.9 than that of 37.8°C, whereas EYFB did not differ. In conclusion, breeder age, broiler strain, and EST differentially influence embryonic metabolism and particularly the availability of oxygen could have contributed to these differences.
    Effects of increased diet density through increased dietary fat level on energy balance characteristics of broilers during the first week of life
    Lamot, D.M. ; Sapkota, D. ; Wijtten, P.J.A. ; Anker-Hensen, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2016
    In: Energy and protein metabolism and nutrition. - Wageningen : Wageningen Academic Publishers (EAAP publication 137) - ISBN 9789086862863 - p. 305 - 306.
    The current study aimed to determine the effect of increased diet density through increasing dietary fat level on growth performance and energy balance characteristics of broiler chickens during the first week of life. The effects of diet density on energy and nitrogen metabolism were studied using a dose response design that comprised 5 dietary fat inclusion levels (3.5, 7.0, 10.5, 14.0, and 17.0%) while maintaining a constant digestible amino acid to energy ratio. Chickens were housed in open circuit climate respiration chambers. Preplanned contrasts were used to determine significant linear and quadratic relationships with diet density. Feed intake and BW gain linearly decreased and gain to feed ratio increased (P<0.001) with increasing dietary density. Nutrient efficiencies (calculated as gain per unit of nutrient consumed) for fat, nitrogen and gross energy linearly decreased (P<0.001). A linear decrease in heat production and the respiratory exchange ratio (CO2/O2) were found with increasing diet density (P<0.001). Protein intake and total energy, fat and protein retention were not affected by diet density. To conclude: increased diet density during the first week of age resulted in improved feed efficiency, but not nutrient efficiency. Protein and fat deposition in the body of broilers was similar.
    Effects of solid feed intake on nutrient utilisation from milk replacer in veal calves
    Borne, J.J.G.C. van den; Alferink, S.J.J. ; Heetkamp, M.J.W. ; Gerrits, W.J.J. - \ 2016
    In: Energy and protein metabolism and nutrition. - Wageningen Academic Publishers (EAAP publication 137) - ISBN 9789086862863 - p. 89 - 90.
    This study was designed to assess the effects of solid feed (SF) supplementation on utilisation of macronutrients derived from milk replacer (MR) in veal calves. Thirty-two male Holstein-Friesian calves were randomly assigned to pairs, and each pair of calves was assigned to one of two levels of SF allowance: 9 or 27 g DM SF/kg0.75 per d. The SF consisted of 80% low-protein concentrates, 10% chopped wheat straw and 10% corn silage based on DM. MR was partly exchanged for SF (as 1:1.7) to achieve similar growth rates across treatments. In four experimental periods, each pair of calves was measured with or without supplementation of lactose, fat or protein (189 kJ extra digestible energy per kg0.75 per d). A higher level of SF intake did not affect energy utilisation for
    growth, but increased methane production and urinary energy excretion in calves. Utilisation of digestible nitrogen for growth increased from 53 to 63% with increasing SF level. Supplementation of protein increased nitrogen retention, but the efficiency of digestible nitrogen utilisation for growth
    decreased. Supplementation of lactose increased digestible nitrogen utilisation for growth by 6 (high SF) to 10% (low SF). The incremental efficiencies of metabolisable energy utilisation for growth were similar for fat (73%) and lactose (74%), whereas the incremental energetic efficiency for protein
    was 39%. In conclusion, the level of SF intake does not affect energy utilisation, but greater intake of low-protein SF and also lactose supplementation increase the efficiency of protein utilisation for growth in veal calves.
    Effects of increased diet density through increased dietary fat level on growth performance, organ size, and dietary fat metabolizability of broilers during the first week of life
    Lamot, D.M. ; Sapkota, D. ; Wijtten, P.J.A. ; Anker-Hensen, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2016
    - p. 204 - 204.
    Embryonic development and heat production
    Nangsuay, A. ; Meijerhof, R. ; Anker-Hensen, I. van den; Heetkamp, M.J.W. ; Kemp, B. ; Brand, H. van den - \ 2016
    International Hatchery Practice 30 (2016)3. - ISSN 0959-9363 - p. 17 - 17.
    Effects of breeder age, broiler strain, and eggshell temperature on development and physiological status of embryos and hatchlings
    Nangsuay, A. ; Meijerhof, R. ; Anker-Hensen, Ilona van den; Heetkamp, M.J.W. ; Souza Morita, V. De; Kemp, B. ; Brand, H. Van Den - \ 2016
    Poultry Science 95 (2016)7. - ISSN 0032-5791 - p. 1666 - 1679.
    Breeder age - Broiler strain - Eggshell temperature - Embryonic development

    Breeder age and broiler strain can influence the availability of nutrients and oxygen, particularly through differences in yolk size and shell conductance. We hypothesized that these egg characteristics might affect embryonic responses to changes in eggshell temperature (EST). This study aimed to investigate the effect of breeder age, broiler strain, and EST on development and physiological status of embryos. A study was designed as a 2 × 2 × 2 factorial arrangement using 4 batches of 1,116 hatching eggs of 2 flock ages at 29 to 30 wk (young) and 54 to 55 wk (old) of Ross 308 and Cobb 500. EST of 37.8 (normal) or 38.9°C (high) was applied from incubation d 7 (E7) until hatching. The results showed that breeder age rather than broiler strain had an influence on yolk size (P = 0.043). The shell conductance was higher in Ross 308 than in Cobb 500 (P <0.001). A high EST resulted in a higher yolk free body mass (YFBM) compared to the normal EST at E14 and E16, but at 3 h after hatch YFBM was lower when eggs were incubated at high EST compared to normal EST (all P <0.001). Cobb 500 eggs yielded embryos with a lower YFBM at E14, E18, and 3 h after hatch (all P <0.05) than Ross 308 eggs. Breeder age had no effect on YFBM, but the RSY weight was higher in embryos from the old flock compared to the young flock embryos at E14 and E16 (both P <0.05). A 3-way interaction among breeder age, strain, and EST was found, especially for incubation duration, navel quality, and relative heart and stomach weights at 3 h after hatch (all P <0.05). Based on the results obtained, we conclude that oxygen availability rather than nutrient availability determines embryonic development, and the egg characteristics affected embryonic responses to changes of EST, especially for variables related to chick quality.

    Computing energy expenditure from indirect calorimetry data: a calculation exercise
    Alferink, S.J.J. ; Heetkamp, M.J.W. ; Gerrits, W.J.J. - \ 2015
    In: Indirect Calorimetry / Gerrits, Walter, Labussière, Etienne, Wageningen : Wageningen Academic Publishers - ISBN 9789086862610 - p. 275 - 284.
    Energy expenditure (Q) can be accurately derived from the volume of O2 consumed (VO2), and the volume of CO2 (VCO2) and CH4 (VCH4) produced. When the measurements are performed using a respiration chamber, VO2, VCO2 and VCH4 are calculated by the difference between the inflow (l/h) and outflow rates (l/h), plus the change in volume of gas in the chamber between successive measurements. There are many steps involved in the calculation of Q from raw data. These steps are rarely published in full detail, nor are they well documented for the training of students, researchers or technical staff. The objective of this chapter is to provide a complete calculation exercise for students at MSc level and researchers or technicians with little background in indirect calorimetry. Based on an example dataset and using a stepwise approach, the calculations used for calibrations, volumes of gas, Q, the respiratory quotient and activity related Q are explained and illustrated.
    Indirect calorimetry: assessing animal response to heat and cold stress
    Gaughan, J.B. ; Heetkamp, M.J.W. ; Hendriks, P. - \ 2015
    In: Indirect Calorimetry : Techniques, computations and applications / W.J.J., Gerrits, E., Labussière, Wageningen : Wageningen Academic Publishers - ISBN 9789086862610 - p. 213 - 230.
    climate control - respiration chamber - reducing error
    Calorimetric thermal stress studies where indirect calorimetry is used as a tool to estimate energy expenditure have been undertaken since this technique was developed. Some examples of these studies are presented in this chapter. The measurement of gas exchange by means of an open-circuit respiration chamber have been done in studies where climate needs to be
    constant but also in studies where animal reactions to differences in climate as part of the experimental design. In the past and in present, animal studies are done in chambers with and without integrated climate controls. Changing climate factors, e.g. temperature, relative humidity, and air speed, may change an animal’s physiological responses. As climate can also affect energy metabolism it is necessary to have a well-designed, accurate and reliable air conditioning system inside a respiration chamber to rule out the unwanted effects of an uncontrollable climate. In this chapter important issues related to the design of climate control
    in respiration chambers are described and methods for improving accuracy are discussed. We conclude that the design of chambers with and without climate control should be undertaken by those that understand animal biology as well as technicians and engineers. Furthermore, the basic physics of heat measurement are discussed and we elaborate about possible biases
    from biological factors and physical factors and how to deal with them.
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