Lower Egg Production Research Articles

Growth and survival rates, puberty and fecundity in captive common barbel (Barbus barbus L.) under controlled conditions

Growth and survival rates (specific growth rate – SGR; survival rate – S) of Barbus barbus L. were recorded in captivity during three years from the larval period (final body weight – W = 0.2 ± 0.03 g; SGR = 13.6 ± 1.1%/day and cumulative survival – S = 76.0 ± 2.5%) to the first reproductive season (W = 62.55 ± 13.5 g; SGR = 0.89 ± 0.05%/day; S = 59.3 ± 1.5%). Final body size and SGR were compared between both sexes. Females reached the significantly higher growth rate (SGR = 0.84 ± 0.01%/day) compared to males (SGR = 0.77 ± 0.01%/day). Early puberty was observed in 17 and 32 months old males and females, respectively. Multi-stripping activity was found out in both sexes during the first reproductive season. In total, 20%, 25.8%, 30.3%, 14.6% and 9% of females were stripped once, twice and three, four and five times, respectively. But all males produced sperm during the entire reproductive season. The highest and the lowest egg production was recorded in the middle (April) and at the beginning (March) of the reproductive season (2155 ± 925 vs. 1279 ± 298 eggs per stripping). The highest and the lowest sperm production was observed at the beginning (March) and at the end (May) of the reproductive season (7.9 ± 0.08 × 10<sup>9</sup> vs. 1.9 ± 0.06 × 10<sup>9</sup> per stripping).

Water- and sediment-quality effects on Pimephales promelas spawning vary along an agriculture-to-urban land-use gradient

Many streams in the U.S. are “impaired” due to anthropogenic influence. For watershed managers to achieve practical understanding of these impairments, a multitude of factors must be considered, including point and nonpoint-source influence on water quality. A spawning assay was developed in this study to evaluate water- and sediment-quality effects that influenced Pimephales promelas (fathead minnow) egg production over a gradient of urban and agricultural land use in 27 small watersheds in Eastern Wisconsin. Six pairs of reproducing fathead minnows were contained in separate mesh cartridges within one larger flow-through chamber. Water- and sediment quality were sampled for an array of parameters. Egg production was monitored for each pair providing an assessment of spawning success throughout the 21-day test periods. Incidences of low dissolved oxygen (DO) in many of these streams negatively impacted spawning success. Nine of 27 streams experienced DO less than 3.1 mg/L and 15 streams experienced DO less than 4.8 mg/L. Low DO was observed in urban and agricultural watersheds, but the upper threshold of minimum DO decreased with increasing urban development. An increase in specific conductance was related to a decrease in spawning success. In previous studies for streams in this region, specific conductance had a linear relation with chloride, suggesting the possibility that chloride could be a factor in egg production. Egg production was lower at sites with substantial urban development, but sites with low egg production were not limited to urban sites. Degradation of water- and sediment-quality parameters with increasing urban development is indicated for multiple parameters while patterns were not detected for others. Results from this study indicate that DO must be a high priority watershed management consideration for this region, specific conductance should be investigated further to determine the mechanism of the relation with egg production, and water- and sediment-quality degrade in relation to urban influence.

Effects of dietary n-6:n-3 ratio on immune and reproductive systems of pullet chicks

The objective of this study was to examine the effects of dietary n-6:n-3 ratio on immune and reproduction systems of Leghorn pullet chicks. A total of 216 Hy-Line W-36 pullet chicks (1 d old) were randomly assigned to 3 diets (n-6:n-3 ratios of 10, 6, and 2) until 22 wk of age. The Optomega-50 (Optivite International Ltd., Nottinghamshire, UK) containing 50% salmon fish oil was used as an n-3 source. Pullets were injected with SRBC suspension at 6 and 9 wk and anti-SRBC titers were measured 7 and 14 d after each immunization. The antibody (Ab) titers for Newcastle disease (ND), avian influenza, infectious bronchitis (IB), and infectious bursal disease (IBD) were determined at 4, 6, 10, 14, and 18 wk of age. Pullets fed diet with the n-6:n-3 ratio of 2 had higher feed consumption and lower BW gain (P < 0.05) compared those fed diets with the ratios of 6 and 10. The results demonstrated that the different dietary n-6:n-3 ratios did not have a significant effect on the anti-SRBC titers in pullets serum (P > 0.05). The Ab production against avian influenza vaccine was increased in pullets fed diet containing the n-6:n-3 ratio of 10 at wk 10 and 14 and increased for ND at only 14 wk (P < 0.05). On the other hand, the Ab response to IBD (14 wk) and IB (14 wk) vaccines was increased when pullets were fed diet containing a ratio of 6 (P < 0.05). The pullets fed diet with the n-6:n-3 ratio of 2 showed lower egg production and late sexual maturity (P > 0.05) whereas ovary weight (P = 0.01) and number of large yellow follicles (P = 0.049) were significantly decreased at first oviposition. Our results revealed that the supplementation of Optomega-50 as a source of n-3 to decrease the n-6:n-3 ratio in diet significantly increased Ab production for ND, IB, and IBD in pullet chicks with slight reduction in reproductive organs weight at early production.

Influence of Different Levels of Lysine, Methionine and Protein on the Performance of Laying Hens after Peak

2 Abstract: This experiment was carried out to determine the effects of different levels of lysine methionine and protein on the performance of 240 Hy-Line W36 layers after peak of production. Ten experimental diets were tested in a 2×5 factorial arrangement with a completely randomized design. Two basal diets (13 and 14% protein) were tested at different levels of lysine and methionine include 10 and 20% lower than NRC, NRC and 10 and 20% above NRC recommendations (0.56, 0.62, 0.69, 0.76 and 0.83% of diet). Levels of Total Sulfur Amino Acids (TSAA) were constantly kept 85% of lysine level in each treatment. During the 3 months of experimental period, egg production, egg weight, egg output, feed intake and conversion and also lysine, TSAA and protein intake were determined. The results indicated that 0.76% lysine and more (10 and 20% above NRC recommendation) with 13% dietary protein led to significantly (p<0.05) higher egg production, egg output and better feed conversion but there was no significant difference regarding egg weight. The difference in performance with different levels of lysine was lower in the 14% dietary protein than that in the 13% one. In the 14% dietary protein, the lowest level (0.56%) of lysine led to significantly (p<0.05) lower egg production and egg output and higher feed conversion. The best performance with the 14% dietary protein belonged to 0.62% dietary lysine (10% below NRC recommendation). Regardless of lysine level, the 14% dietary protein had significantly (p<0.05) higher egg production, egg output and feed intake than 13% dietary protein group but there was no significant difference regarding egg weight and feed conversion totally. The best and most economical performance belonged to the 0.76% lysine of 13% protein group. The results of this experiment indicated that reducing dietary protein and addition of lysine and TSAA to the diets of post peak laying hens can obtain an equa l performance to the higher dietary protein thus reducing production costs and some problems related to excess nitrogen in poultry diets.

Distribution and production of plankton communities in the subtropical convergence zone of the Sargasso Sea. II. Protozooplankton and copepods

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 426:71-86 (2011) - DOI: https://doi.org/10.3354/meps09047 Distribution and production of plankton communities in the subtropical convergence zone of the Sargasso Sea. II. Protozooplankton and copepods Nikolaj G. Andersen1,4, Torkel Gissel Nielsen1,2,*, Hans Henrik Jakobsen2,1, Peter Munk2, Lasse Riemann3,4 1National Environmental Research Institute, Aarhus University, Department of Marine Ecology, 4000 Roskilde, Denmark 2National Institute of Aquatic Resources, DTU Aqua Section for Oceanecology and Climate, Technical University of Denmark, DTU Kavalergården 6, 2920 Charlottenlund, Denmark 3Department of Natural Sciences, Linnaeus University, 39182 Kalmar, Sweden 4Marine Biological Section, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark *Corresponding author. Email: tgin@aqua.dtu.dk(Second superscript numbers indicate present addresses) ABSTRACT: The oligotrophic Sargasso Sea in the western part of the North Atlantic Ocean is influenced by a complex set of oceanographic features that might introduce nutrients and enhance productivity in certain areas. To increase our understanding of the variability in plankton communities and to determine the potential reasons why Atlantic eels Anguilla spp. use this area for spawning, we investigated the distribution and productivity of the zooplankton community across the Subtropical Convergence Zone (STCZ) in the Sargasso Sea in March and April 2007. The vertical and horizontal distributions of protozoans and metazooplankton were investigated at 33 stations along 3 north to south transects ranging from 64 to 70°W to a depth of 400 m. Copepods dominated the metazooplankton, while heterotrophic athecate dinoflagellates dominated the protozoan biomass. Other important groups were appendicularians, gastropod larvae and ostracods. Most of the recorded metazoan groups responded numerically to the frontal features (i.e. the surfacing of the isotherms) with high abundance in the STCZ compared with areas north and south of this. Juvenile copepod growth and egg production peaked in the STCZ, with a weight-specific growth rate of juvenile copepods ranging from 0.09 to 0.21 d–1, and a much lower specific egg production in the order of 0.01% d–1. The Sargasso Sea is described as oligotrophic, but the availability of athecate dinoflagellates and ciliates in the STCZ potentially leads to an enhanced mesozooplankton secondary production, which may in turn be available to organisms at higher trophic levels such as larvae of Atlantic eels. KEY WORDS: Sargasso Sea · Ciliates · Heterotrophic dinoflagellates · Copepods · Convergence zone Full text in pdf format PreviousNextCite this article as: Andersen NG, Nielsen TG, Jakobsen HH, Munk P, Riemann L (2011) Distribution and production of plankton communities in the subtropical convergence zone of the Sargasso Sea. II. Protozooplankton and copepods. Mar Ecol Prog Ser 426:71-86. https://doi.org/10.3354/meps09047Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 426. Online publication date: March 28, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

EFFECT OF MASH DIETARY FIBER ON PERFORMANCE AND CANNIBALISM IN LAYING HENS

An experiment was conducted to observe the effect of dietary fiber given in mash form onperformance and cannibalism mortality in laying hens. Three different diets: a wheat-based diet, a guargum diet (a wheat-based diet + 20 g/kg guar gum) and a lucerne meal diet (a wheat-based diet + 40 g/kglucerne meal) in mash form were offered for 12 weeks. The results showed that birds fed guar gum diethad the lowest intake (p&lt;0.01), egg weight (p&lt;0.05), body weight (p&lt;0.05) and the lowest eggproduction (p&lt;0.01) compared to those fed other diets. Diets did not have a significant effect (p&gt;0.05)on feed to egg ratio and cannibalism mortality, but numerically the birds fed the guar gum diet had thehighest mortality (11.3%) and the lucerne diet had the lowest (6.9%). The lack of profound differenceswas probably due to the diets were given in mash form. In conclusion, diets containing high soluble NSPreduced the performance and increased the mortality due to cannibalism in laying hens. The use of mashform may have a potential in reducing the negative effect of soluble NSP on cannibalism.

Canola, corn, and vegetable oils as alternatives for wheat germ oil in fruit fly larval diets

Four wheat germ oil alternatives (corn oil, vegetable oil, canola oil with 10% vitamin E, and canola oil with 20% vitamin E), purchased from a local supermarket in Hawaii, were added to a fruit fly liquid larval diet as a replacement for wheat germ oil in the rearing of fruit fly larvae. The oils were tested on three species of fruit flies in Hawaii, Ceratitis capitata (TSL strain), Bactrocera dorsalis, and Bactrocera cucurbitae. They were evaluated for their efficacy in replacing WGO, based on: pupal recovery (%), larval duration (d), pupal weight (mg), adult emergence (%), adult fliers (%), mating (%), egg production per female per day, egg hatch (%), and peak egging period (d). Diets with WGO and without any oil were used as controls. The objective of the study was to select the most cost effective alternative oils with the best performance to replace the currently used WGO, which is pricey and hard to find. The results showed that there was no significant difference in performance among the tested oils in B. cucurbitae and B. dorsalis as regards the above mentioned parameters. Lower mating rate was observed in B. cucurbitae from those reared in vegetable oil and canola oil (10% vitamin E) diet. Lower egg production and egg hatch were obtained with B. dorsalis whose larvae were reared in vegetable and canola oil (both 10% and 20% vitamin E). Vegetable oil diet seemed to reduce pupal weight, shorten larval duration, and increase pupal recovery of C. capitata. The results suggest that WGO can be substituted with corn oil, vegetable oil, or canola oils for B. cucurbitae, while corn oil is a better alternative for B. dorsalis, and vegetable oil is best for C. capitata.

Influence of iron on fatty acid and sterol composition of marine phytoplankton and copepod consumers

We conducted laboratory experiments to determine the influence of iron on the fatty acid (FA) and sterol composition of the diatom Thalassiosira oceanica, the cryptophyte Rhodomonas salina, the prymnesiophyte Isochrysis galbana, and the copepod Acartia tonsa that fed on these algae. Algal cells were cultured with no added Fe or with Fe added at 100 nmol L−1. Fe‐deficient culture medium resulted in lower growth rates, cell volumes, and photosynthetic efficiencies for all algal species. The total mass of FA per cell was 2.2–3.1 times as high in Fe‐replete cells as in Fe‐deficient cells; on a carbon–normalized basis, the FA concentrations of Fe‐replete algal cells were 1.4–1.5 times as high. Differences were noted between Fe treatments for specific saturated, monounsaturated, and polyunsaturated FAs within each algal species. Total C‐normalized 20:5ω3 + 22:6ω3 concentrations declined 18%, 25%, and 35% in Fe‐deficient T. oceanica, R. salina, and I. galbana, respectively. Across all species, another consistent difference in FA composition between Fe treatments was for 18:4ω3, which had a C‐normalized concentration that was ∼ twofold higher in Fe‐replete algae. No consistent pattern for all algal species was evident for Fe effects on algal sterol concentration and composition, and in response to Fe limitation sterols were conserved more than C and FAs in these cells. Copepods feeding on Fe‐replete and Fe‐deficient algae displayed smaller differences in FA and sterol concentrations than in their algal diets. Differences in lipid concentration and composition between Fe‐replete and Fe‐deficient algae may partly explain the lower egg production rate of copepods fed Fe‐deficient algae.

Kanzawa spider mites acquire enemy-free space on a detrimental host plant, oleander

Studies have proposed that predators of herbivores suffer significant fitness losses from the defense chemicals of host plants, and that herbivores adapted to these chemicals may experience reduced predation risk when residing on such plant species. We examined the effects of oleander, Nerium indicum Mill. (Apocynaceae), a host plant of the spider mite, Tetranychus kanzawai Kishida (Acari: Tetranychidae), on their prime predator, Neoseiulus womersleyi (Schicha) (Acari: Phytoseiidae), and tested the hypothesis that this host plant provides enemy-free space. At the study sites, T. kanzawai occurred on oleander shrubs; in contrast, although N. womersleyi was present in the area, no individuals were found on oleander. Tetranychus kanzawai feeding on oleander negatively affected the settlement, development, and egg production of N. womersleyi. The lower egg production was a result of both the direct effects of oleander and the indirect effects via T. kanzawai. Previous studies showed that the fitness of T. kanzawai in the presence of N. womersleyi was lower than that in the absence of the predator, and lower on oleander than on other palatable host plant species in the absence of predators. Our findings suggest that N. womersleyi may not be able to invade T. kanzawai patches on oleander shrubs, which results in the fitness of T. kanzawai being higher on oleander than on other host plant species in the same area when N. womersleyi is present. This supports the hypothesis that T. kanzawai acquires enemy-free space on oleander using the direct and indirect adverse effects of oleander on their predators as major defense mechanisms.

Effects of dietary minerals on postmolt performance of laying hens

Four hundred and fifty Single Comb White Leghorn commercial layers (66-67 weeks-old) were housed 2 birds per cage for the molting procedure. The hens were divided into 5 treatment groups with 90 layers per treatment and 30 layers in each replicate per treatment group following completely randomized design. During molt period (2 Weeks), experimental birds were randomly assigned to five-treatment groups viz., A (15 ppm copper sulphate), B (20 ppm zinc oxide), C (20 ppm aluminium oxide), D (balanced layer diet without added minerals) and E (without induced molting as control). The birds in groups A, B, C and D were offered respective experimental diets at the rate of 30 g/bird except bird's in-group E (ad libitum) and lighting program was followed as 12L: 12D. During rest period (3 Weeks) the birds in groups A, B, C and D were given respective experimental diet at the rate of 50 g/bird for first 2 weeks of the rest period. rd During 3 week of rest period the birds in groups A, B, C and D were given experimental diets at the rate of 60 g/bird and were placed on lighting program of 14L:10D. During production phase, the birds of all groups were fed a balanced layer diet (ad libitum) and birds were placed again on lighting program of 16L:8D. The results showed that the birds fed diets A, B and C showed greater (p 0.05) in ovarian weights were found among minerals supplemented groups A, B and C. The non-molted birds (group E) exhibited the greatest (p<0.05) feed intake over the 2 weeks molt whereas birds on minerals supplemented diets ate the least (p<0.05) feed. On average non-molted hens fed a balanced layer diet and molted hens fed without minerals diet had lower (p<0.05) egg production when compared with molted hens fed mineral added diets after 20 weeks post molt. However, molted hens fed without minerals diet had significantly higher egg production than that of non-molted hens fed a balanced layer diet. Egg shell quality and Haugh unit score improved (p<0.05) in molted hens compared to non-molted hens. Based on the results of this study, mineral feeding appears to be the best alternative to without mineral feeding in molting methods and yield comparable results.

Adaptation of wheat and protein-mineral concentrate intakes by individual hens fed ad libitum in sequential or in loose-mix systems

1. Feed intake and performance of birds given sequential or loose-mix feeding was investigated from 19 to 42 weeks of age. A complete diet was fed as control (C). A balancer diet (50) was fed either sequentially (S50) or in a loose-mix (L50) with wheat. This diet was formulated to provide a similar nutritive value as C assuming a 50 : 50 diet and wheat intake. Another balancer diet (25) was fed sequentially (S25) or in a loose-mix (L25) with wheat. The diet was to provide a similar nutritive value as C assuming 75 : 25 diet and wheat intakes. In sequential feeding, only wheat was fed in the morning (4 h after lights-on) and the balancer diet in the late afternoon (4 h before lights-off). In the loose-mix treatment, a mixture of the two diets was fed throughout the 16-h daily light. Each treatment was given ad libitum to 25 birds in individual cages. 2. Birds fed on L25 had lower total feed intakes than those receiving C, S50 or S25. Protein intake was reduced with L25 compared to C, S50, S25 and L50. Metabolisable energy (ME) intake was, however, similar among all treatments. Egg production and weight were reduced with L25 compared to S50 and S25. Body weight (BW) was lowered with L25. However, there was high individual variation in all variables. 3. Feeding system (sequential vs loose-mix) had no effect on ME intake. However, the loose-mix treatment reduced feed and protein intake due to lower balancer diet intake. It also resulted in low egg production, egg and BWs compared to sequential feeding. The weights of pancreas and gizzard were heavier with sequential and loose-mix compared to the control. 4. The loose-mix treatment reduced egg-laying performance. Sequential feeding resulted in similar egg-laying performance to conventional feeding and thus could be used to advantage in situations where it is applicable.

Effects of supplemental levels of hesperetin and naringenin on egg quality, serum traits and antioxidant activity of laying hens

Hesperetin and naringenin phytochemicals are naturally occurring flavanoids in citrus fruits. The purpose of this study was to evaluate the effects of supplementing different levels of extracted hesperetin and naringenin on egg quality, serum traits and antioxidant activity in laying hens. Two experiments were conducted, each for 10 weeks, in a completely randomized experiment design. Each had 100 Leghorn laying hens (26 weeks old) randomly assigned into five groups ( n = 20) based on dietary categories of hesperetin 0, 0.5, 1, 2, 4 g/kg and naringenin 0, 0.5, 1, 2, 4 g/kg. Experimental results indicated that there was increased (P<0.05) egg production in the 1 g/kg naringenin-supplemented group, but lower (P<0.05) egg production in the hesperetin- and naringenin-supplemented groups given 4 g/kg. Cholesterol content (per gram yolk) and total cholesterol content (per egg) were lower (P<0.05) in the hesperetin- and naringenin-supplemented groups as compared to the control group, and the 2 g/kg hesperetin- and naringenin-supplemented groups showed the most significant difference. Both serum cholesterol and triglyceride concentrations were lower (P<0.05) in the 2 g/kg hesperetin- and naringenin-supplemented groups. The SOD and catalase activities, scavenging O 2 − and iron-chelating abilities were higher (P<0.05) in the 2 g/kg hesperetin- and naringenin-supplemented groups, and the trolox equivalent antioxidant capacity was higher (P<0.05) in the 2 g/kg naringenin-supplemented group. The results confirmed that both hesperetin and naringenin could lower serum and egg yolk cholesterol levels, and improve the antioxidant activities, however the measured variables generally showed significant quadratic responses to increasing amounts of the compounds. The recommended supplementation level of hesperetin and naringenin is 2 g/kg of the basal diet for reduced serum and yolk cholesterols contents and increased antioxidant capacity.

Expressing gK gene of duck enteritis virus guided by bioinformatics and its applied prospect in diagnosis

BackgroundDuck viral enteritis, which is caused by duck enteritis virus (DEV), causes significant economic losses in domestic and wild waterfowls because of the high mortality and low egg production rates. With the purpose of eliminating this disease and decreasing economic loss in the commercial duck industry, researching on glycoprotein K (gK) of DEV may be a new kind of method for preventing and curing this disease. Because glycoproteins project from the virus envelope as spikes and are directly involved in the host immune system and elicitation of the host immune responses, and also play an important role in mediating infection of target cells, the entry into cell for free virus and the maturation or egress of virus. The gK is one of the major envelope glycoproteins of DEV. However, little information correlated with gK is known, such as antigenic and functional characterization.ResultsBioinformatic predictions revealed that the expression of the full-length gK gene (fgK) in a prokaryotic system is difficult because of the presence of suboptimal exon and transmembrane domains at the C-terminal. In this study, we found that the fgK gene might not be expressed in a prokaryotic system in accordance with the bioinformatic predictions. Further, we successfully used bioinformatics tools to guide the prokaryotic expression of the gK gene by designing a novel truncated gK gene (tgK). These findings indicated that bioinformatics provides theoretical data for target gene expression and saves time for our research. The recombinant tgK protein (tgK) was expressed and purified by immobilized metal affinity chromatography (IMAC). Western blotting and indirect enzyme-linked immunosorbent assay (ELISA) showed that the tgK possessed antigenic characteristics similar to native DEV-gK.ConclusionsIn this work, the DEV-tgK was expressed successfully in prokaryotic system for the first time, which will provide usefull information for prokaryotic expression of alphaherpesvirus gK homologs, and the recombinant truncated gK possessed antigenic characteristics similar to native DEV gK. Because of the good reactionogenicity, specificity and sensitivity, the purified tgK could be useful for developing a sensitive serum diagnostic kit to monitor DEV outbreaks.

Chemical composition of meat and egg yolk of hybrid and Italian breed hens reared using an organic production system

A trial was done to study the chemical composition of meat and egg yolk of laying hens belonging to different genotypes reared using an organic production system. Two commercial hybrid hens (Hy-Line Brown and Hy-Line White 36) and 2 Italian dual-purpose breed hens (Ermellinata di Rovigo and Robusta Maculata) were reared from 25 to 44 wk of age. During the experimental period (July to December), the environmental temperature decreased from about 25 to 13 degrees C and the RH increased from 62 to 73%. The photoperiod was 16L:8D. Meat and egg yolks of 44-wk-old hens were analyzed. The Italian breeds showed higher meat production and lower egg production when compared with the hybrids. Genotype affected protein, lipid, and ash content of breast and thigh meat. Hy-Line White and Ermellinata di Rovigo showed the lowest (P<0.01) breast lipid and Hy-Line White had the lowest (P<0.01) thigh lipid. Hy-Line White showed higher (P<0.05) breast and thigh cholesterol. Genotype affected egg yolk cholesterol, which was higher (P<0.01) in Italian breeds than in hybrids. The fatty acid profiles of meat and yolk were significantly affected by genotype. The hybrid and Robusta Maculata meat and egg fatty acid composition may be considered to be more favorable to human health. The results indicate that the ability of laying hens to incorporate fatty acids is genetically dependent and a possible interaction between strain and environmental conditions may exist for the absorption and utilization of dietary components.

Influence of limestone particle size on performance and egg quality in laying hens aged 24–36 weeks and 56–68 weeks

One hundred and twenty ISA Brown hens aged 24–36 weeks and 120 ISA Brown hens aged 56–68 weeks were used to study the influence of limestone particle size and the animal's age on laying performance and egg quality. Two diets were used: a diet containing calcium carbonate in fine limestone particles (diet LF with limestone particles <0.5 mm), and a diet containing calcium carbonate in coarse limestone particles (diet LC with 91% of particles larger than 0.8 mm and smaller than 2.0 mm). The experimental unit consisted of a group of 10 hens, thus each treatment was replicated six times per age group. Hen-day egg production was higher and egg weight lower in young hens than in old hens (P<0.001). In younger hens, hen-day egg production was 87.0 and 89.4% in birds fed LF and LC, respectively. Corresponding hen-day egg production values in older hens were 73.5 and 79.9%. Lower egg production in hens aged 56–68 weeks was compensated in part by higher egg weight which was 62 and 63 g in younger hens fed diets LF and LC, respectively, and 67 and 68 g in older hens fed diets LF and LC, respectively (P<0.001). In younger and older hens, feeding the LC diet increased shell weight by 0.2 and 0.2 g (P<0.001), shell thickness by 4 and 8 μm (P<0.001), shell Ca content by 2 and 2 mg/g DM (P=0.003), albumen height by 0.2 and 0.3 mm (P=0.003), and Haugh units by 0.8 and 0.2 (P=0.014), respectively. No increase in the shell breaking strength was observed. It can be concluded that LC with a particle size of 0.8–2.0 mm should be considered rather than fine ground limestone when formulating diets for laying hens both in the early and the late phase of production.

Reproductive biology of the Panama graysbyCephalopholis panamensis(Teleostei: Epinephelidae)

The reproductive biology of the Panama graysby Cephalopholis panamensis was studied from collections and behavioural observations made in the Gulf of California from 2001 to 2006. Histological examinations, particularly the identification of gonads undergoing sexual transition, confirmed a protogynous hermaphroditic sexual pattern. The population structure and mating behaviour provided further support for protogyny. Size and age distributions by sex were bimodal, with males larger and older than females and sex ratios biased towards females. Mating groups consisted of a large male and several smaller females, and courtship occurred in pairs during the evening. Results on spawning periodicity and seasonality were incomplete, but histological data, monthly gonado-somatic indices (I(G)) and behavioural observations suggest that adults spawned around the full moon from May to September. Certain aspects of their reproductive biology (e.g. protogyny and low egg production) indicate that C. panamensis is particularly vulnerable to fishing and would benefit from a management policy in Mexico.

Vitamins A, E and fatty acid composition of the eggs of caged hens and pastured hens

AbstractIn the US farmers often market pastured poultry eggs for a premium price, claiming animal and human health benefits. We examined how moving pastured hens to forage legumes or mixed grasses influenced hen (Gallus gallusL.) egg omega-3 fatty acids and concentrations of vitamins A and E. We also compared the eggs of the pastured hens to those of hens fed a commercial diet in cages. We used a cross-over design to compare pasture species: 75 sister hens were assigned to one of three pasture treatment groups: (1) alfalfa (Medicago sativaL.), (2) red and white clover (Trifolium pretenseL. andTrifolium repensL.) or (3) mixed cool season grasses. Groups were rotated to all three pasture treatments, each for 2 weeks and supplemented with 70 g commercial hen mash bird−1day−1. Pasture botanical composition, forage mass, leaf to total ratio and plant fatty acid composition were compared among pasture treatments. Eggs of the pastured hens were compared to eggs of 50 sister hens that were fed only commercial hen mash in cages for the entire 6 weeks. Forage parameters varied somewhat, but did not explain plant linolenic acid variation. Seventeen of the 18 quantified egg fatty acids, and vitamin A concentrations did not (P&lt;0.05) differ among the three pasture treatment groups. Eggs of the hens that foraged grasses had 23% more (P&lt;0.0001) vitamin E than eggs of hens that foraged clover. Compared to eggs of the caged hens, pastured hens' eggs had twice as much vitamin E and long-chain omega-3 fats, 2.5-fold more total omega-3 fatty acids, and less than half the ratio of omega-6:omega-3 fatty acids (P&lt;0.0001). Vitamin A concentration was 38% higher (P&lt;0.05) in the pastured hens' eggs than in the caged hens' eggs, but total vitamin A per egg did not differ. At the end of the experiment, pastured hens weighed 14% less and averaged 15% lower hen-day egg production than caged birds (P&lt;0.0001). Results suggest that grass pastures may enhance vitamin E in eggs of pastured hens more than clover, and pastured hens supplemented with commercial mash will produce eggs with significantly more vitamin E and total omega-3 fatty acids compared to eggs from caged hens fed only commercial hen mash. Pastured hens may have lower body weight and egg production than caged hens, unless they are supplemented adequately to meet their dietary energy and crude protein needs.

The considerable adult size variability in wood feeders is optimal

1. The life history of wood feeders was modelled in order to explain the multiseasonality of development and the great variability of adult size in this group.2. The model was parameterised with experimental bioenergetic and reproductive data for the xylem feeder Aredolpona rubra (Coleoptera: Cerambycidae).3. The length of the developmental period, which together with food quality directly determines adult size and indirectly determines the number of eggs laid, was optimised.4. The results show that multi‐seasonal larval development maximises fitness under conditions of low food quality, relatively low predation pressure, and the presence of hostile periods during the year.5. The variability of the number of seasons needed to complete development within a wood‐feeder population is a consequence of development time optimisation and the unavoidable extension of the egg‐laying period. These insects have an evolutionary dilemma: to eclose late in a given season at smaller size, bringing about low egg production and low offspring value, or to grow bigger to the next season, jeopardising their lives.6. The results of the model predict wood‐feeder developmental patterns that depend on the tree tissue inhabited.

Abundantly expressed hepatic genes and their differential expression in liver of prelaying and laying geese

Geese have a short egg-laying period and a low egg production rate. To induce and maintain egg laying, genes related to generating hepatic lipid for yolk deposition should be adequately expressed. Liver mRNA from 6 laying geese was extracted and used for construction of a full-length enriched cDNA library. About 2,400 clones containing gene sequences were determined and National Center for Biotechnology Information Gallus gallus Gene Index databases were used to compare and analyze these sequences. Ten highly expressed genes were selected to determine the differential expression between laying and prelay goose liver. Tissue distribution data showed that very low density apolipoprotein II, liver type fatty acid binding protein, vitellogenin I, and vitellogenin II transcripts were specifically expressed in the liver of laying geese. Ovoinhibitor, preproalbumin, α-2-hs-glycoprotein, and vitamin D binding protein mRNA were highly expressed in the liver and to a lesser extent in other tissues. Ovotransferrin mRNA was expressed in liver, ovary, oviduct, shell gland, brain, and adipose tissues. The concentration of transthyretin mRNA was high in the liver and brain. The mRNA concentrations of liver type fatty acid binding protein, α-2-hs-glycoprotein, and transthyretin in the livers of laying and prelay geese were not different. The concentrations of hepatic ovotransferrin, ovoinhibitor, preproalbumin, very low density apolipoprotein II, vitellogenin I, vitellogenin II, and vitamin D binding protein mRNA were higher in the liver of laying geese than in prelay geese, suggesting that these genes may be involved in laying function or lipid metabolism related to egg formation.

Costly sexual harassment in a beetle

Abstract The optimal number of mating partners for females rarely coincides with that for males, leading to sexual conflict over mating frequency. In the bruchid beetle Callosobruchus maculatus, the fitness consequences to females of engaging in multiple copulations are complex, with studies demonstrating both costs and benefits to multiple mating. However, females kept continuously with males have a lower lifetime egg production compared with females mated only once and then isolated from males. This reduction in fitness may be a result of damage caused by male genitalia, which bear spines that puncture the female’s reproductive tract, and/or toxic elements in the ejaculate. However, male harassment rather than costs of matings themselves could also explain the results. In the present study, the fitness costs of male harassment for female C. maculatus are estimated. The natural refractory period of females immediately after their first mating is used to separate the cost of harassment from the cost of mating. Male harassment results in females laying fewer eggs and this results in a tendency to produce fewer offspring. The results are discussed in the context of mate choice and sexual selection.