An in vitro culture method for chick embryos obtained from the anterior portion of the magnum of oviduct

1. Chick embryos, obtained from the anterior portion of the magnum of the oviduct 60 to 80 min after the preceding egg had been laid, were cultured in vitro in small and large recipient eggshells until hatching.

2. Of 82 embryos cultured, 46.3% had survived to day 4 of incubation, and 19.5% survived to hatching.

3. The method for culturing embryos used in this experiment could facilitate research on the in vitro manipulation of early chick embryos.     

Simple in vitro system for molecular studies of early avian development in the quail

1. The development of quail embryos incubated in ovo and cultured in vitro was compared in terms of basic morphological and biochemical criteria.

2. Blastoderm culture in vitro may be a convenient system for investigation of molecular aspects of early development.     

Development of prenatal acoustic interaction in the Muscovy duck (Cairina Moschata)

1. The development of prenatal acoustic communication was investigated in Muscovy ducks, comparing the vocalisation activities and call types in isolated eggs and pairs of embryos (two eggs in shell contact).

2. Incubator experiments showed that the number of vocalisations in embryos which had mutual acoustic contact was nearly twice that of isolated ones.

3. An acoustic interaction, that is, an exchange of signals, was only recognised after the first chick had hatched, that is, between embryos and chicks.

4. Specific call types used for communication were the double call and the trill call.     

Antimicrobial substances and chick growth promotion: Comparative studies on selected compounds in vitro and in vivo

1. Antibacterial activity of selected compounds in vitro and their ability to promote growth when added to the diet of chicks were not correlated.

2. The difference in growth‐promoting activity between streptomycin, which was active, and kanamycin which was not, was not related to their effects on the flora adhering to the wall of the crop, jejunum or ileum, to their relative toxicity to the chick nor to differences in their stability in the diet.

3. When low concentrations ofkanamycin or streptomycin were given, the antibiotic was concentrated in the caecal contents. In contrast, penicillin was undetectable in the caeca of birds given high concentrations of benzyl penicillin.

4. In chicks given benzyl penicillin, the numbers of Streptococcus faecium increased at the expense of Strep, faecalis. This probably resulted from changes in the crop flora.

5. Birds given high dietary concentrations of benzyl penicillin showed improved weight gains, in spite of increased numbers of Escherichia coli in the small intestine.     

Inhibitory effects of epidermal growth factor on progesterone production of ovarian granulosa cells in Tsaiya duck (Anas platyrhynchos var. domestica)

1.?The purpose of this study was to investigate the effects of epidermal growth factor (EGF) on progesterone (P₄) secretion from ovarian granulosa cells in Tsaiya ducks (Anas platyrhynchos var. domestica).

2.?We obtained the largest (F1) follicle from Tsaiya duck, the granulosa layer was separated and the cells were isolated according to their proximity to the germinal disc.

3.?The granulosa cells were cultured in vitro, the culture media and the cells were used to determine P₄ and steroidogenic enzyme concentrations, respectively.

4.?P₄ concentrations were decreased in cultured granulosa cells taken proximal to the germinal disc (GD) compared to those distal to the germinal disc (NGD).

5.?EGF inhibited both basal and ovine luteinising hormone (oLH)-induced P₄ concentrations. It also inhibited the P₄ secretion via protein kinase A (PKA) pathway when cultured with GD and NGD granulose cells (mixed together) in vitro.

6.?Western blot results showed decreased concentrations of cytochrome P450 side-chain cleavage (P450scc) enzyme, 3β-hydroxysteroid dehydrogenase (3β-HSD) enzyme and steroid acute regulatory (StAR) protein expression, when the cells were co-treated with EGF and oLH.

7.?The inhibitory effect of oLH-induced P₄ production was attenuated by EGF by the addition of MAP-erk kinase (MEK) inhibitor (PD98059) suggests EGF may inhibit P₄ production by affecting via the mitogen-activated protein kinase (MAPK) pathway.     

Effects of short intermittent lighting on food consumption and performance of dwarf broiler breeders and progeny

1. Two hundred and sixty four dwarf broiler breeder hens were subjected to ad libitum or restricted feeding and to four lighting patterns: 15L (bright light):9D (dark), 15L:9d (dim light), 2L:10d: 1L:11d, (0.5L:3.5d) × 6.

2. Breeder hens fed ad libitum and subjected to either conventional or intermittent lighting ingested respectively, 25 g and 14 to 17 g more than hens restricted to 115 g/d.

3. Body weight was greater in hens fed ad libitum irrespective of the lighting pattern and of the amount of food intake.

4. Persistency of egg production was impaired by intermittent lighting.

5. Ad libitum feeding reduced egg fertility. The decrease was larger in breeder hens on intermittent lighting.

6. Hatchability was increased in hens submitted to the symmetrical lighting pattern (0.5L:3.5d).

7. Egg and chick weights were higher in hens fed ad libitum.

8. Shell index and shell breaking strength increased in restricted hens on the intermittent lighting pattern (0.5L:3.5d) × 6.

9. The best performance was obtained in restricted hens on the conventional lighting pattern.     

Different characteristics in chick embryos of two broiler lines differing in susceptibility to ascites

1. The relationship between the length of incubation, hatching, hypoxic condition, thyroid hormones and the occurrence of ascites were studied in embryos of 2 broiler lines differing in susceptibility to the ascites syndrome.

2. Both the time of external pipping (ep) and hatching of embryos from the ascites‐resistant (AR) broiler line was earlier compared to the ascites‐sensitive line (AS). The interval between internal pipping (ip) and ep was the same between the lines, but the interval between ep and hatching was shorter in the resistant line.

3. The T₃ and T₄ concentrations in plasma of the AS line were lower compared to the AR line.

4. Analyses of partial pressures of oxygen (pO₂) and carbon dioxide (pCO2) in the air cell of the egg revealed that at day 18 the AS embryos had lower pO₂ and higher pCO₂ concentrations compared to the AR embryos.

5. The delay in hatching of the AS embryos might induce a more pronounced and/or extended hypoxic environment, thereby creating an environment that evokes ascites.     

In vitro initiation of the acrosome reaction in the emu (Dromaius novaehollandiae)

1. An assessment of the efficiency of the acrosome reaction (AR) provides an important predictor of the fertilizing potential of semen and for diagnosis of the causes of infertility. A standardized protocol was therefore developed for initiation of the acrosome reaction in emu spermatozoa in vitro, and the role of CaCl₂ or perivitelline membrane (PVM) proteins in determining the outcome of the reaction was investigated.

2. The acrosome reaction (assessed by FITC-PNA) was successfully induced in live spermatozoa by incubation for 2 min in NaCl-TES medium supplemented with 5 mM CaCl₂. The maximum response was 32% live acrosome-reacted spermatozoa (LAR) achieved after 10 min incubation.

3. Compared to the outcome with 5 mM CaCl₂ or PVM protein alone, the response was significantly better with a combination of PVM protein and CaCl₂.

4. A significant variation in the percentage of LAR spermatozoa among individual males was observed. No treatment affected the percentage of dead acrosome-reacted spermatozoa.

5. The results emphasize the important role played by both PVM proteins and Ca²⁺ in the in vitro initiation of the acrosome reaction.     

Manipulations of germ‐cell populations in the gonad of the fowl

1. Embryos of the domestic fowl have been partially sterilised by injecting the drug busulphan into 24‐h incubated eggs.

2. Some of these embryos were injected with primordial germ cells (PGCs) after 55 h of incubation to attempt to repopulate the gonads.

3. Primordial germ cells transfected with a defective retrovirus containing the reporter gene lac Z were shown to settle in these sterilised gonads.

4. Quantitative histology of 6‐d embryos showed that busulphan produced 75% sterilisation but that PGCs could repopulate these gonads.

5. The technique of producing such germ line chimaeras is of value in studying cell kinetics, gonad differentiation and the production of transgenics.     

The influence of tungsten on the molybdenum status of poultry

1. Large doses of tungsten, administered to the chick either by injection or by feeding, increased tissue concentrations of tungsten and decreased tissue concentrations of molybdenum and tissue activities of xanthine dehydrogenase.

2. The rate of loss of large doses of tungsten from the liver occurred in an exponential manner with a half‐life of 27 h.

3. When tungsten was administered to chicks fed on a semi‐synthetic diet containing abnormally low concentrations of molybdenum, the activity of hepatic xanthine dehydrogenase was reduced to negligible levels.

4. The alterations in molybdenum metabolism resulting from the administration of large doses of tungsten to the chick appears to be the result of tungsten toxicity and not of molybdenum deficiency.

5. Deaths from tungsten toxicity occurred when tissue concentrations of tungsten were increased to approximately 25 μzg/g liver. At this tissue tungstencon centration the activity of xanthine dehydrogenase was zero.     

Plasma alpha 1‐acid glycoprotein concentration in broilers: Influence of age,sex and injection of escherichia coli lipopolysaccharide

1. The influence of age, sex and injection of Escherichia coli lipopolysaccharide (LPS) on the plasma concentration of alpha‐1 acid glycoprotein (AGP) was determined in broilers using the single radial immunodiffusion method.

2. Plasma AGP concentration increased in the 3 d after hatching, and then stabilised at 240 ± 33 μg/ml up to 14 d of age.

3. No sex‐related differences in plasma AGP concentration were observed up to 6 weeks of age.

4. A single injection of 900 μg LPS per chick resulted in a 5‐fold increase in AGP concentration compared with that in saline‐injected chicks. Multiple injections of LPS (200 μg/chick every 2d for 14d) caused only a 50% increase in AGP concentration.     

Maturation and ovulation of Japanese quail oocytes under in vitro conditions

1. An in vitro system for ovulation and maturation of Japanese quail oocytes is described.

2. Ovarian follicles removed from the ovary at 2, 4 or 6 h before the estimated time of ovulation may ovulate under in vitro conditions.

3. The presence of progesterone in the medium had a stimulatory effect on the process of maturation, as has been shown for Xenopus oocytes.     

The occurrence of giant fibres in different muscles of two chicken genotypes

1. The occurrence of Giant Fibres (GF) in three muscles (Pectoralis major (PM), Iliotibialis lateralis and Semimembranosus) with different types of energy metabolism was studied in slow- and fast-growing chicken strains.

2. A total of 20 one-day-old Leghorn chicks (slow-growing) and 20 broiler (Ross 508) chicks (fast-growing) were reared to 100 and 45 d, respectively.

3. A small percentage of GF was seen in pre rigor muscle samples even at 3 min post mortem in both genotypes and in all muscle types studied.

4. From 3 min to 24 h post mortem GF increased both in Leghorn and broiler chickens but to a different extent according to muscle type and genotype.

5. The highest GF 24 h post mortem value was found in the PM muscles belonging to the fast-growing broiler line.

6. It was concluded that every type of muscle can develop GF, but this phenomenon is more evident in the PM especially in animals selected for increased growth rate.     

The relationship between hatching egg weight and subsequent performance of broiler chickens

Small eggs constitute a high proportion of the eggs laid by pullets. The literature shows that chick hatching weight is strongly correlated with egg weight, but evidence on the influence of egg weight on hatchability and subsequent performance of chicks is less certain.

The aim of this experiment was to determine the profit returned at 12 weeks by broiler chickens hatched from eggs ranging in weight from 44 g. to 58 g. at one gram intervals and to determine how competitive and separate rearing might modify the relationship.

A total of 6000 eggs were collected during 10 days from a 28‐week‐old, broiler breeding flock and graded into the above mentioned egg weight classes. From these, a total of 3480 day‐old broilers were housed. Each egg weight class was equally represented and balanced for sex.

Hatchability and fertility showed no consistent trend with egg weight for eggs above 46 g., but below the 47 g. level there was a trend of declining fertility and hatchability.

A strong positive relationship was found between the weight of the chick at 1 day of age and egg weight for both males and females with no significant difference overall in body weight between the two sexes.

Body weight to 12 weeks was found to be strongly related to egg weight, in a linear fashion, though this influence declined with age.

There was a greater influence of egg weight on body weight at all ages in the separate rearing treatment compared with competitive rearing but this was not significant after 10 weeks.

Egg weight had an important bearing on body weight and profit at 12 weeks, but no effect on food conversion or mortality.

The increased profit over food costs per 100 day‐old chicks was found to be 52.75 cents for the separately reared birds respectively for each 3 g. increase in egg weight.     

Storage of hatching eggs: The effect on total incubation period

1. A time‐lapse photographic technique has been developed which enables routine recording of the hatching times of up to 192 chicken embryos.

2. Storage of eggs for 14 d caused a delay of 134 h in the mean total incubation period.

3. Female embryos hatched about 3 h earlier than males in the non‐stored eggs but there was no difference between the sexes in eggs stored for 14 d.

4. Rate of weight loss during incubation was similar in both non‐stored and stored eggs: there was no relationship between weight loss at 19 d incubation and total incubation period.

5. Hatchability of fertile eggs was 19.5% lower in eggs stored for 14 d and proportionately more embryos died between 4 d and 18 d incubation than in the non‐stored eggs.     

EDACO,a derivative of myricetin,inhibits the differentiation of Gaoyou duck embryonic osteoclasts in vitro

1. This study determined the effects of (E)-3-(2-(4-(3-(2,4-dimethoxyphenyl)acryloyl)phenoxy)ethoxy)-5,7-dimethoxy-2-(3,4,5-trimethoxyphenyl)-4H-chromen-4-one (EDACO) on the differentiation of Gaoyou duck embryonic osteoclasts cultured in vitro.

2. Bone marrow mononuclear cells (BM-MNC) were collected from 23-d-old Gaoyou duck embryos and induced by macrophage colony-stimulating factor and receptor activator of nuclear factor κB ligand in the presence of EDACO at different concentrations (i.e. 10, 20, 40, 80 and 160 µM). Tartrate-resistant acid phosphatase (TRAP) staining and resorption ability determination were conducted.

3. Results suggested that EDACO suppressed the shaping of positive multinucleated cells and the number of TRAP-positive cells in the 20, 40, 80 and 160 μM EDACO groups was significantly decreased (P < 0.05 or P < 0.01). Besides, the absorption activity of differentiated duck embryonic osteoclasts was significantly inhibited (P < 0.05) in both 80 and 160 μM EDACO groups.

4. Overall, EDACO can inhibit the differentiation of BM-MNC into mature osteoclasts in duck embryos.1     

Efficiency of the cloacal sexing technique in greater rhea chicks (Rhea americana)

1. The feasibility and accuracy of the cloacal sexing technique in greater rhea chicks was assessed using chicks of two captive populations of greater rhea in Córdoba, Argentina.

2. A total of 46 greater rhea chicks of 2 to 3 months of age were randomly arranged into three groups and the members of each group were sexed by a different operator.

3. A feather of each chick was plucked for sexing through a molecular method and results were used as controls.

4. Sex was correctly assigned by cloacal inspection in 98% of the cases. Chick manipulation was easily performed and no infections or traumatic lesions were observed a posteriori.

5. Cloacal sexing of rhea chicks up to 3 months of age does not affect animal welfare and should be considered an efficient alternative to molecular methods.     

Similar developmental fluctuations of hepato-renal xanthine oxidoreductase gene expression and xanthine oxidase activity in layer and broiler chicken embryos

1. Xanthine oxidase (XO) has many physiological functions associated with the synthesis of both antioxidant (uric acid: UA) and numerous oxidants (e.g. H₂O₂), which makes it an important regulator of the cellular redox potential involving organogenesis. The ontogenetic study of hepatic and renal XO makes a better understanding of the putative role of this enzyme in the development of these tissues.

2. Developmental changes of gene expression of xanthine oxidoreductase (XOR), XO activity and UA content of liver and kidney tissues in both broiler and layer chicken embryos were examined during incubation d 14–21.

3. In both strains, hepatic XOR gene expression peaked on d 21 while renal XOR gene expression did not change.

4. The XO activity was higher in kidney than liver in both strains. Hepatic XO activity of both strains peaked on d 18 and thereafter was decreased on d 21. Renal XO activity peaked on d 18 and from then on did not show any significant changes until d 21 in both strains.

5. The UA content was higher in kidney vs. liver in both strains. The hepatic and renal UA values of the both strains increased significantly from d 14 to d 21.

6. The present results showed dissimilar behaviour of XOR gene expression, XO activity and UA content of liver and kidney tissues in both broiler and layer chicken embryos.     

Explanted embryo culture: In vitro and in ovo techniques for domestic fowl

1. Embryos of the domestic fowl (72 h old) have been explanted into shell‐less cultures or ‘surrogate’ eggshells, in order to investigate the possibility of rearing these embryos to hatching.

2. Rocking embryo cultures during the first half of incubation enhanced embryo growth.

3. Embryos explanted into ‘surrogate’ eggshells of either other individuals or other species have been successfully ‘hatched’.

4. A normal chorioallantois is formed in these surrogate eggshells. This enables a functional albumen sac to form and eggshell resorption to be achieved.

5. Embryos grown in ‘surrogate’ eggshells are slightly smaller than controls but otherwise normal.

6. The technique provides opportunities for genetic engineering experiments.     

Effects of phytoestrogens on testosterone secretion by Leydig cells from Biłgoraj ganders (Anser anser)

1. The aim of this study was to examine ganders at different stages of the reproductive season and the effect of: (1) diets with high phytoestrogen content and (2) in vitro phytoestrogen treatment on testosterone secretion by isolated Leydig cells.

2. Thirty-six male Bi?goraj geese were fed control diets with low phytoestrogen content (containing grass meal) and diets with high phytoestrogens (containing alfalfa meal and soy).

3. Testes were obtained from both groups of ganders at three different times of the breeding season: peak of reproductive activity (March), second half of reproductive activity (May) and beginning of photorefractoriness (July).

4. Isolated Leydig cells were incubated with LH as well as genistein, daidzein, equol and coumestrol and the concentration of testosterone in the medium was determined by radioimmunoassay.

5. The mean weight of testes from ganders in May and July decreased relative to their weights in March, but no significant differences among experimental groups were noted.

6. No differences were observed in basal and LH-stimulated testosterone secretion by Leydig cells of ganders fed the control diets and the diets with higher phytoestrogen content. In July, LH did not stimulate testosterone secretion in either group. In vitro treatment with genistein, daidzein and equol (5 and 50?µM) inhibited basal and LH-stimulated testosterone production by Leydig cells from both groups. Coumestrol (5 and 50?µM) inhibited basal testosterone secretion only in March in the control group.

7. Dietary exposure to phytoestrogens had a slight effect on in vitro testicular secretion in ganders. In vitro treatment with phytoestrogen inhibited testosterone production by Leydig cells. Genistein showed the strongest effect and coumestrol had the weakest influence on testicular secretion.