Effects of an anti-androgen in the laying hen (Gallus domesticus)

The daily injection of the anti-androgen, cyproterone acetate, into regularly laying hens failed to prevent ovulation immediately. The delayed response suggested that testosterone is not part of the ovarian positive feedback stimulus resulting from the presence of an ovulable follicle and leading to ovulation. Ovarian changes in treated birds, and their unimpaired response to LH-RH, suggested that the drug might be acting by altering ovarian steroid metabolism.     

Measurement of blood flow distribution by radioactive microspheres in the laying hen (Gallus domesticus)

• 1.1. Blood flow distribution was examined in 12 normothermic laying hens by microspheres injected via the brachial artery into the root of the aortic arch above the aortic valves.
• 2.2. Double reference sampling (brachial and sciatic) accounted for uneven microsphere distribution between upper and lower body arterial flows.
• 3.3. This easily accessible injection site yielded results comparable to those attained by left atrial injections.
• 4.4. Blood flow (ml/min g tissue) was highest in the spleen (8.2); intermediate in the brain, kidneys. adrenals, liver, follicles (1.1–3.1); below 0.5 in the skin. muscle, respiratory tract and post ovulatory follicle. Hyperthermia markedly changed this order.

     

Effects of propionate on the acid microclimate of hen (Gallus domesticus) colonic mucosa

• 1.1. Short-chain fatty acid absorption in hen colon is protonated across the apical border coupled to an apical electrogenic proton pump.
• 2.2. The surface pH of the isolated colonic epithelium was 6.27 ± 0.05, when incubated in Krebs-phosphate buffer pH 7.0.
• 3.3. Propionate 7 and 40mmol/l in the incubation medium (pH 7.0) increased microclimate pH to 6.47 ± 0.04 and 6.56 ± 0.04. Inhibition of metabolic activity by potassium cyanide 1 mmol/1 increased surface pH to 6.66 ± 0.06.
• 4.4. The calculated concentration of propionic acid in the microclimate is near-linearly related to the propionate concentration. Thus, the acid microclimate is not responsible for the Michaelis-Menten like kinetics of propionate transport.

     

Hydrolysis of plasma triacylglycerol-rich lipoproteins from immature and laying hens (Gallus domesticus) by lipoprotein lipase in vitro.

Explants of pig small intestine were maintained at 37 degrees C in organ culture for periods up to 24 h in a system using Trowell T-8 medium supplemented with 10% foetal-calf serum. The mucosal morphology was well preserved during culture, as judged by light and electron microscopy. The explant contents of protein and two brush-border enzymes, microvillus aminopeptidase (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5), were not significantly modified during culture compared with controls, but a moderate, continuous release of both protein and enzyme activities into the medium was observed. Continuous labelling with [35S]methionine resulted in an even incorporation of radioactivity in the protein components, and the rate of labelling only moderately decreased over the 24 h period. The polypeptide compositions of sucrase (EC 3.2.1.48)--isomaltase (EC 3.2.1.10), maltase--glucoamylase (EC 3.2.1.20) lactase (EC 3.2.1.23)--phlorizin hydrolase (EC 3.2.1.62), microvillus aminopeptidase and aspartate aminopeptidase (EC 3.4.11.7) synthesized during culture were studied, and some were found to be similar to those of the pro-forms of the enzymes isolated from animals that had had their pancreatic duct disconnected 3 days before being killed. These results confirmed earlier findings of the existence of pro-forms of some of the microvillar enzymes and thus indicate a low activity of pancreatic proteinases in the culture system.     

Effect of indomethacin and vasotocin on oviposition in the hen (Gallus domesticus)

The interrelationship between prostaglandins (PG) and vasotocin (AVT) in the oviposition of the domestic hen was investigated. Single or combined injections of indomethacin (IND), an inhibitor of PG synthesis, and AVT gave delay or induction of oviposition. Injection (i.m.) of IND (5 mg/kg) 5 h before oviposition resulted in 15.1 h (+/- 0.93) delay of oviposition. Injection (i.v.) of AVT (0.1 microgram/kg) 2.5 h before oviposition caused premature oviposition within a few minutes (3.1 +/- 0.2). Combined injection of IND and AVT at 5 h and 2.5 h, respectively, before oviposition caused the delay of oviposition (15.8 h +/- 0.8). The results indicate that IND blocked the induction of oviposition by AVT.     

The vocal expression of feeding motivation and frustration in the domestic laying hen, Gallus gallus domesticus

Thwarting of feeding behaviour in the laying hen results in an increase in stereotyped pacing, displacement preening, and the gakel-call. These behaviours therefore reflect the frustration arousal caused by the thwarting of feeding behaviour. This raises the question whether the level of frustration also varies with the intensity of the motivation to perform the thwarted behaviour. This study investigated the relationship between the intensity of the motivation and level of frustration on the one hand and the gakel-call on the other hand. In Experiment 1, the strength of the motivation to feed was varied by thwarting hens in their feeding behaviour in an operant procedure after different durations of food deprivation (0, 8, 23 and 47 h). Trend analysis showed that with increasing hunger state, an increasing number of gakel-calls was given. No effect of treatments on temporal characteristics of the gakel-call was found. In Experiment 2, the level of frustration was varied by reducing or increasing the duration of access to food for food-deprived hens compared to the duration of access during training. It was assumed that a shorter duration of access to food compared to training would elicit frustration, which in turn would affect the performance of behaviours indicative of thwarting. However, we found neither a relation between the number of gakel-calls nor the temporal features of the gakel-call and the duration of access to food. Possibly, the differences between treatments were not large enough to induce differences in frustration level. Also, other factors that might have influenced the motivation are discussed.     

Physiological and behavioural responses in the hen (Gallus domesticus) to nociceptive stimulation

1. Physiological and behavioural parameters were examined in the hen in response to a noxious and non-noxious stimulus. 2. Two distinct patterns emerged depending on the type of stimulus (noxious----crouching, non-noxious----wingflapping). 3. The responses seen in the hen to the two different types of stimuli appear to be similar to those occurring in mammals.     

Prostaglandin production by the largest preovulatory follicles in the domestic hen (Gallus domesticus)

An injection of 5 micrograms of gonadotropin-releasing hormone (GnRH) into hens 8 h prior to oviposition advanced the expected time of oviposition by approximately 1 h. The plasma concentration of progesterone increased approximately 1 h earlier in GnRH-injected hens in comparison to saline-injected hens. The plasma concentration of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) increased significantly (p less than 0.05) at the time of oviposition in both the GnRH- and saline-injected hens. Significantly (p less than 0.05) greater concentrations of prostaglandin F2 alpha (PGF2 alpha) were assayed in media containing the largest preovulatory follicles collected at oviposition than in media containing the second and fifth largest preovulatory follicles collected at the same time. No prostaglandin was detected in media containing small, nonhierarchial follicles. The concentration of PGF2 alpha in media containing granulosa cells from the largest preovulatory follicle was significantly greater (p less than 0.05) than in media containing 4 times as many theca cells. Ovine luteinizing hormone (oLH) alone or in combination with arachidonic acid had no effect on PGF2 alpha output from granulosa cells collected 6 h before oviposition, whereas A23187 caused a small stimulation of PGF2 alpha output. However, treating cells first with oLH and then with A23187 stimulated a 15- to 20-fold increase in PGF2 alpha. None of these stimuli enhanced the already high output of PGF2 alpha when added to incubations of granulosa cells collected within 5 min after oviposition. These data suggest that the granulosa cells of the largest preovulatory follicle are the major intraovarian source of prostaglandin and that production of PGF2 alpha is associated with the preovulatory surges of gonadotropins and steroid hormones preceding oviposition.     

Histological study of follicular atresia in the ovary of the domestic hen (Gallus domesticus)

Semi-serial (1 in 20) sections of ovaries were studied and only two types of atresia were identified--non-bursting and bursting. Smaller, non-yolky follicles (less than 1 mm diameter) showed non-bursting atresia. Atresia in follicles greater than 1 mm diameter was invariably of the bursting type which involved the rupture of the follicular wall, and the extrusion of yolk and cellular debris through the rupture site into the stroma. However, this rupture site was small and consequently was not visible in every section but it could always be seen when the follicle was followed in semi-serial sections. The mitotic index of granulosa cells in bursting atretic follicles was much lower than that for normal follicles. The most common criteria for distinguishing non-bursting atretic follicles were the extremely shrunken, irregularly shaped oocytes and the separation of the granulosa from the theca. In bursting atretic follicles, reliable indications were the presence in the ooplasm of some cells or cellular debris, and disorganization of the yolk and granulosa tissue. The presence of pycnotic nuclei in the granulosa cells was not a consistent feature of all atretic follicles of the hen.     

Histochemical demonstration of the presence of serotonin in the hen (Gallus domesticus) reproductive tract

The purpose of the present study was to demonstrate visually and localize the presence of serotonin (5-HT) in the ovary and oviduct of the domestic hen using a histochemical Falck-Hillarp method. Experiments were carried out on White Leghorn laying hens with no egg in the shell gland. The specific yellow fluorescence, indicating the presence of 5-HT, was found both in the ovary and all examined oviductal parts. The strongest fluorescence was present in the ovarian stroma containing small follicles with a diameter under 4 mm. In the wall of the largest preovulatory follicle a very strong fluorescence was located mainly in the theca layer. In the oviductal parts, the intensity of 5-HT fluorescence in the infundibulum and magnum was fairly strong, whereas in the isthmus and shell gland it was weak. Fluorescence seen in the infundibulum, magnum, and isthmus was primarily localized along the luminal borders of the fold surface epithelium. In the shell gland 5-HT fluorescence was found within the uterine folds, especially in the tubular glands. Moreover, the presence of an egg in the definite oviductal segment (infundibulum or isthmus) increased the intensity of yellow fluorescence in this part.     

Decreased androstenedione production with increased follicular maturation in theca cells from the domestic hen (Gallus domesticus)

Collagenase-dispersed theca cells from the 3rd and 4th largest ovarian follicles (T3) were responsive to LH stimulation of both oestrogen and androstenedione production, whereas theca cells from the largest follicle (T1) failed to respond to the gonadotrophin stimulation. Similarly, 8-bromo cAMP and forskolin were more effective in stimulating oestrogen and androstenedione production in T3 than in T1 cells, indicating that post-receptor events were involved in the decreased LH responsiveness of T1 cells. The C17-20-lyase activity, as measured by conversion of [3H]17-hydroxyprogesterone to androstenedione, was greatly reduced in T1 cells as compared to T3 cells. The results demonstrate that a decrease in C17-20-lyase activity, in addition to a decrease in aromatase activity, contributes to the loss of LH-stimulated steroidogenesis in mature theca cells.     

Divergent selection on feather pecking behaviour in laying hens (Gallus gallus domesticus)

A selection experiment was initiated in 1996 in which selection for (HP line) and against (LP line) feather pecking was performed. The foundation stock was a White Leghorn layer strain established in 1970 and maintained since then as a random bred control line at the Institute. Six hatches were produced over three generations. At the age of 68 weeks (generation 0, 1996), 35 weeks (generation 1, 1997), 30 weeks (generation 2, 1998), and 27 weeks (generation 3, 1999) female birds were transferred to observation pens and their feather pecking behaviour was recorded. In each generation, 30 females and 8 males were selected from approximately 200 females and 60 males. The selection criterion was breeding value estimated by animal model on the trait 'number of bouts of feather pecking per bird per hour'.Feather pecking behaviour in adult hens was significantly higher in HP than in LP. In generation 2 the following was recorded: 3.10 versus 1.37 bouts per bird per hour (P<0.01), 7.04 versus 3.58 pecks per bird per hour (P<0.05) and the proportion of hens recorded feather pecking in the 180min observation period was 67 versus 56% (P<0.05). In generation 3 the following was recorded: 4.56 versus 0.63 bouts per bird per hour (P<0.001), 13.9 versus 2.51 pecks per bird per hour (P<0.001) and the proportion of hens recorded feather pecking in the 180min observation period was 75 versus 49% (P<0.001).In generation 3, plumage condition was better in LP on neck, breast, back, wings and tail, as well as overall (P<0.001). Body weight did not differ between lines in generation 2, but in generation 3, HP hens were on average heavier than LP hens at the age of 27 weeks (1435g versus 1371g, P<0.001).     

Lipoprotein lipase of ovarian follicles in the domestic chicken (Gallus domesticus) (38537).

A lipase, bearing the characteristics of adipose tissue lipoprotein lipase (LPL) has been characterized in avian ovarian granulosa cells. The activity is low in cells from follicles weighing less than 0.5 g; in heavier follicles which have entered the rapid growth phase, significant activity (1 mumole fatty acid/mg protein/hr) could be identified. Granulosa LPL provides follicular tissues with the requisite enzyme system to hydrolyze very low density lipoprotein triglyceride en route to the oocyte.     

Steroid metabolism in granulosa and theca interna cells from preovulatory follicles of domestic hen (Gallus domesticus)

The capability of granulosa and theca interna cells, from preovulatory follicles of the domestic hen, to metabolize steroid precursors was evaluated. Granulosa and theca interna cells were isolated from ovarian preovulatory follicles at three different developmental stages: F1, F3 and F5. Tritiated pregnenolone (P5), progesterone (P4), dehydroepiandrosterone (DHEA), androstenedione (A4) and testosterone (T) were employed as precursors and their metabolic products were evaluated. The major metabolite of P5 by granulosa cells was P4, but we also observed low amounts of 5β-pregnandione. DHEA metabolism by granulosa cells yielded mainly A4, and minute quantities of 5β-androstan-3,17-dione (5β-dione) were detected. The only significant metabolite obtained in granulosa cells from A4 was 5β-dione, whereas T was only transformed into A4. On the other hand, P5 metabolism by theca interna cells yielded A4 as the main product, also P4, 17α-OHP4, 17α-OHP5, 5β-pregnandione, and DHEA, were found. When DHEA was the precursor A4 was produced in higher amounts than 5β-dione. A4 was mainly transformed into 5β-dione. In similar conditions, T was transformed into A4. These results show that granulosa cells have enzymatic activities of 3β-hydroxysteroid dehydrogenase/5-4 isomerase (3β-HSD from P5 and DHEA), 17β-hydroxysteroid dehydrogenase (17β-HSD from T) and 5β-reductase (from P5, DHEA and A4). Whereas theca interna cells have enzymatic activities of cytochrome P450c17 (from P5 and P4), 3β-HSD (from P5 and DHEA), 17β-HSD (from T) and 5β-reductase (from P4, DHEA and A4). These data support the concept that theca interna cells have the ability to synthesize androgens from progestins produced in granulosa cells. In addition, since theca interna cells did not show the capacity to aromatize androgens suggests that interaction between theca interna and theca externa cells occurs in vivo, thus confirming the three cell model for estrogen production. Furthermore, the fact that other metabolites were produced both in granulosa and theca interna cells, but in a different extent, suggests that complex mechanisms are participating in the regulation of steroid synthesis in avian ovary follicles.     

Gluconeogenesis in isolated chicken (Gallus domesticus) liver cells.

1. Gluconeogenesis was studied in isolated avian hepatocytes. The highest rate of glucose production obtained was from lactate, followed by dihydroxyacetone, glyceraldehyde, and fructose. Alanine was converted to glucose at only about 4% the rate of lactate. 2. Addition of 10 mM sorbitol, xylitol, or ethanol to the hepatocytes increased glucose production from pyruvate 25-40%, while glycerol addition increased it only 9%. 3. Addition of beta-hydroxybutyrate had no effect on glucose production from lactate or pyruvate. 4. Addition of octanoate had no effect on glucose production from pyruvate, but depressed it from lactate at 5 mM. 5. Differences in the formation of glucose from various substrates suggest some basic differences in the mode of glucose production between the chick and the rat and guinea-pig.     

Effects of fasting on serum lipids and lipoprotein profiles in the egg-laying hen (Gallus domesticus)

The effects of a 24-h fast on serum lipids and lipoprotein profiles in commercial laying hens were investigated. Blood was analyzed at 34 and 46 weeks of age from Single Comb White Leghorn hens that had been either fed ad libitum or had been fasted for 24 h prior to collection. At 12 weeks, birds were divided into 16 biological isolation units, with 8 replicate units assigned to each treatment group. Four birds out of 10 in each unit were tagged for bleeding. Parameters evaluated included total serum cholesterol and triglycerides, mean diameters of very low density lipoproteins (VLDLs) for the 10th, 50th, and 90th percentiles of serum total VLDL, mean total population VLDL particle diameter (MPD), and percentage serum cholesterol recovered in VLDL, low density lipoprotein (LDL), and high density lipoprotein (HDL) fractions. Fasting led to decreases in total serum cholesterol and triglycerides, and a decrease in mean serum VLDL particle diameter in the 90th population percentile. At Week 34, percentage serum cholesterol recovered from LDL was increased, whereas percentage serum cholesterol recovered from HDL was decreased due to fasting. At Week 46, MPD and percentage serum cholesterol recovered from VLDL were decreased, whereas percentage serum cholesterol recovered from HDL was increased due to fasting. It was concluded that a 24-h fast decreased serum lipids (cholesterol and triglycerides) and the size of VLDL particles in the 90th population percentile in commercial laying hens. Furthermore, bird age influenced the effects of a 24-h fast on MPD and the redistribution of serum cholesterol among VLDL, LDL, and HDL particles.