Changes in egg production rate induced by progesterone injection in broiler breeder hens.

A polycystic ovarian follicle (PCOF) syndrome associated with high baseline concentrations of progesterone (P4) without preovulatory luteinizing hormone (LH) surges has been reported in turkey hens. The PCOF syndrome could be induced in turkey hens by injecting P4 (0.33 mg/kg per d) daily early in the reproductive period for 10 to 12 d and then waiting 3 wk for the syndrome to develop. It was hypothesized that an arrest in laying associated with the PCOF syndrome could be induced by daily injection of P4 in restricted-fed broiler breeder hens. Hens were divided into 5 treatment groups and were injected subcutaneously daily with P4 in canola oil at dosages of 0, 0.17, 0.33, 0.5, and 1.5 mg/kg per d for 13 d, at 14 wk of egg production when they were 41 wk of age. Blood samples were collected on d 7 and 13 immediately before P4 injection. Oviductal and ovarian morphologies were measured at necropsy 1 d after the last P4 injection. Egg production rate was reduced by injection of P4 at dosages < 0.17 mg/kg per d. At dosages of 0.5 and 1.5 mg/kg per d, ovarian hierarchical follicles had regressed. None of the broiler breeder hens had the PCOF syndrome at necropsy, but a high incidence of hens holding hard-shelled uterine eggs for several days was observed. Concentrations of LH decreased with P4 injection at > 0.17 mg/kg per d, and P4 concentrations were increased with P4 injection at > 0.5 mg/kg per d. Estradiol-17beta (E2) concentrations were decreased at all P4 dosages. It was concluded that egg production rate was reduced by daily injection of P4 at dosages > 0.17 mg/kg per d, and egg production ceased and ovarian follicles and the oviduct regressed at dosages > 0.50 mg/kg per d. The PCOF syndrome, however, was not induced in restricted-fed broiler breeder hens by P4 injection.

Effect of chronic progesterone injection on egg production in Japanese quail.

Young laying turkey hens ceased laying and developed a polycystic ovarian follicle (PCOF) syndrome 3 wk after injections of progesterone (P4) ceased. It was hypothesized that laying Japanese quail chronically injected with progesterone (P4) would respond with reduced or arrested egg production and altered ovarian morphology similar to that seen in turkeys expressing the PCOF syndrome, and could thus serve as a model to study the PCOF syndrome. To test these hypotheses, 6 trials were conducted with young photosensitive Japanese quail photostimulated to induce sexual maturity with either 24L:0D or 14L:10D at 6 or 8 wk of age, and used after 3 to 5 wk of egg production. The quail were injected once daily at dosages of 0, 0.17, 0.33, 0.5, 1.5, 3.0, or 4.5 mg of P4/kg per d, or twice daily at dosages of 0 and 1.5 mg of P4/kg for 8 to 14 d and were then necropsied 1 d after the last injection or after waiting an additional 8 to 14 d. During the injection period, egg production was not different among P4 dosages <1.5 mg of P4/kg per d, but decreased at dosages of 1.5 mg of P4/kg per d or greater. A decrease in egg production was found with twice daily injections of 1.5 mg of P4/kg. The decrease in egg production rate ceased and egg production resumed 5 to 7 d after the last injections of 3.0 and 4.5 mg of P4/kg per d or twice-daily injections of 1.5 mg of P4/kg. Compared with control hens, a high percentage of hens (from 12 to 75%) held a hard-shelled egg in the uterus during single daily injections at dosages of 3.0 and 4.5 mg of P4/kg per d and twice daily injections of 1.5 mg of P4/kg. Ovary and oviductal weights, and number of hierarchical follicles were not changed after chronic P4 injection, but more atretic follicles were found in hens at the end of 8 to 12 d of P4 injection. In conclusion, a decreasing egg production rate was induced by chronic P4 injection, but the decrease ceased and egg production resumed 5 to 7 d after the last injections in laying Japanese quail. Young quail hens, unlike young turkey hens, did not develop a PCOF-like syndrome after P4 injection.

Development of a cannulation procedure for broiler breeder hens.

A cannulation and serial bleeding procedure has been developed to monitor the peripheral patterns of hormones associated with reproduction for up to 10 d in broiler breeder hens. Hens were cannulated via the jugular vein and returned to individual cages. The unrestrained cannulated hens were connected to a tether and swivel system that permitted constant infusion for maintenance of the cannula prior to serial bleeding and unrestrained long-term serial bleeding for up to 10 d. In a short-term experiment hens were bled every 12 min for 36 h, and in a long-term experiment hens were bled hourly for 10 d. In these experiments, 1.5-mL blood samples were collected at each time point with sodium citrate as the anticoagulant. To avoid hemodilution, after removal of plasma the red blood cells were reconstituted with saline to the original volume and returned to the hen of origin. Collection of serial blood samples was successful from 94% of hens in the short-term experiment and 79% of hens in the long-term experiment. Egg production was not affected (P > 0.05) during the 6 wk following serial bleeding in the short-term experiment. For hens that continued laying, egg production for 10 d prior to cannulation was not different (P > 0.05) from egg production for the 10 d during serial bleeding in the long-term experiment. However, late in the reproductive cycle many hens (25%) stopped laying when serially bled. It is concluded that this cannulation procedure can be used to study short-term or long-term peripheral patterns of hormones associated with oviposition and ovulation in laying broiler breeder hens.

Preovulatory surge patterns of luteinizing hormone, progesterone, and estradiol-17beta in broiler breeder hens fed ad libitum or restricted fed.

Spontaneous ovulations are induced by preovulatory surges of luteinizing hormone (LH) and progesterone (P4) during ovulatory cycles in birds, but estradiol-17beta (E2) levels are relatively constant. Egg production is enhanced in restricted fed (RF) in comparison with ad libitum fed (FF) broiler breeder hens, but changes in concentrations and peripheral patterns of LH, P4, and E2 during ovulatory cycles in broiler breeder hens are poorly documented. The hypothesis of this study was that high resolution patterns of peripheral LH, P4, and E2 during preovulatory surges would not be different between FF and RF broiler breeder hens. Seven FF and 6 RF broiler breeder hens were photostimulated with 16 L:8 D at 22 wk of age. At 28 wk of age, the hens were cannulated for serial blood sampling and switched to a 24L:0D photoperiod to allow preovulatory surges of LH and P4 to run freely. Three days after cannulation, hens were serially bled every 12 min for 36 h. The FF hens were heavier than the RF hens (5.60 +/- 0.35 vs. 3.60 +/- 0.28 kg, respectively; P < 0.01). During the 10 d before cannulation, total egg production of the FF and RF hens (8.3 +/- 1.4 and 6.8 +/- 1.3 eggs, respectively; P = 0.08) and normal egg production (5.6 +/- 1.8 and 6.5 +/- 1.8 eggs, respectively; P = 0.37) were not different. The FF hens, however, had more abnormal eggs than the RF hens (2.7 +/- 1.7 and 0.3 +/- 0.8 eggs, respectively; P < 0.01). None of the hormonal measurements was different between the FF and RF hens (P > 0.05). The concentrations of hormones for the FF and RF hens, respectively, were as follows: baseline LH (2.79 +/- 0.45 vs. 2.94 +/- 0.60 ng/mL) and P4 (1.68 +/- 0.56 vs. 1.41 +/- 0.43 ng/mL), overall mean LH (3.18 +/- 0.45 vs. 3.10 +/- 0.46 ng/mL) and P4 (2.32 +/- 0.55 vs. 2.09 +/- 0.91 ng/ mL), preovulatory surge amplitude of LH (5.43 +/- 1.27 vs. 3.88 +/- 1.24 ng/mL) and P4 (6.08 +/- 2.09 vs. 6.71 +/- 3.91 ng/ mL), preovulatory surge duration of LH (7.52 +/- 1.80 vs. 5.74 +/- 3.18 h) and P4 (7.52 +/- 1.42 vs. 8.20 +/- 1.24 h), and overall mean E2 (0.25 +/- 0.05 vs. 0.23 +/- 0.05 ng/mL). In conclusion, there were no differences in total egg production or normal egg production between FF and RF broiler breeder hens, but the FF hens laid more abnormal eggs. Also, there were no differences in the concentrations or peripheral patterns of LH, P4, and E2 during preovulatory surges between the FF and RF broiler breeder hens.

Influence of photoperiod and age of photostimulation on the incidence of polycystic ovarian follicle syndrome in turkey breeder hens.

An arrest in egg laying associated with a polycystic ovarian follicle syndrome (PCOF) has been recently reported early in the egg production period in turkey hens photostimulated at 30 wk of age (WOA) with continuous light. When autopsied 2 to 3 wk after laying ceased, the ovaries of PCOF hens contained an increased number of mature size (F1) yolky follicles in comparison with normally laying hens plus several larger cystic follicles, while their oviducts were equal in weight to oviducts of hens laying normally. Four experiments were conducted to examine effects of age at photostimulation and photoperiod [14L:10D (14L) or continuous lighting 24L:0D (24L)] on the incidence of the PCOF syndrome. Turkey hens of the egg line were given short-day photostimulation of 6L:18D at 16 WOA and then photostimulated with either 14L or 24L at various ages between 26 to 70 WOA. Egg production was followed for 6 to 8 wk, and hens that stopped laying eggs during this period were autopsied 2 to 3 wk later to determine presence and incidence of the PCOF syndrome. At 26 WOA, the PCOF incidence was 80% with 24L lighting and 31% with 14L lighting (P = 0.006). At 28 WOA, the PCOF incidence was 56% with 24L lighting and 25% with 14L lighting (P = 0.072). At 31, 34, and 41 WOA, there were no differences (P > or = 0.10) in incidence of the PCOF syndrome between the 24L and 14L treatments. Within the 24L treatment, the PCOF incidence at 26 and 28 WOA (80 and 56%) were greater than at 31 WOA and older ages (< or = 20%; P < or = 0.025). Within the 14L lighting treatment, the PCOF incidence was not different among ages (26 WOA, 31% to 48 WOA, 0%; P > or = 0.05). It was concluded that the incidence of the PCOF syndrome is greater when photosensitive Egg line turkey hens are photostimulated at relatively young ages (less than 31WOA) and with 24L in comparison to 14L lighting.

The development of an immunoblotting assay for the quantification of liver fatty acid-binding protein during embryonic and early posthatch development of turkeys (Meleagridis gallopavo).

Turkey (Meleagridis gallopavo) liver cytosolic fatty acid binding protein (FABP) was purified and used as a standard for quantification. An immunoblotting procedure was developed to study the ontogeny of liver cytosolic FABP during embryonic and early posthatch development in turkey poults. Liver FABP activity was also determined indirectly through the use of gel filtration chromatography followed by a ligand-binding assay. The specific activity of liver FABP (ng/mg of cytosolic protein) increased with length of incubation, peaking initially at Day 22, declining between Days 22 and 25, and increasing again from hatch (Day 28) to 6 d posthatch. The specific activity of liver FABP increased 12-fold between Day 13 of incubation and 6 d posthatch compared with total activity, which increased from 946 to 1.01 x 10(6) ng/liver during the same period, a 1,067-fold increase. The results from both analytical procedures were similar, suggesting that the immunoblot method could be used to quantify liver FABP concentrations. The observed increases in FABP activity throughout the embryonic period and first days after hatching paralleled increases in liver lipid concentration. Therefore, liver FABP may be associated with hepatocyte fatty acid transport and metabolism during the latter stages of incubation and early posthatch period.

Interval between preovulatory surges of luteinizing hormone increases late in the reproductive period in turkey hens.

In turkey hens, the egg production rate is relatively high early during a reproductive period, but declines as the period progresses. Among lines with different egg production potential, the interval between preovulatory surges of LH is the primary determinant of the egg production rate. The main objective of this study was to determine whether the decline in egg production rate late during an egg production period is also associated with a difference in the interval between LH preovulatory surges. A group of photosensitive turkey hens (Early) were photostimulated with continuous light (24L:0D) at 40 wk of age to induce egg laying, and serial blood samples were collected after about 3 wk of egg production. A second group of hens (Late) were housed in floor pens and photostimulated with 14L:10D at 40 wk of age for a normal 36-wk reproduction period and were then switched to 24L:0D lighting for 2 wk before collection of serial blood samples. Continuous light photostimulation was used for at least 2 wk before and during serial blood sampling to avoid potential masking effects of diurnal lighting on the interval between LH surges. The Early (n = 12) and Late (n = 16) hens were cannulated 3 days before being serially bled hourly for 10 days. The mean interval between preovulatory surges of LH was shorter in the Early hens than in the Late hens (26.1 +/- 2.5 h and 34.7 +/- 3.9 h, respectively). The intra-hen LH surge interval coefficient of variation was lower in the Early hens than in the Late hens (7.2% and 18.6%, respectively). The inter-hen LH surge interval coefficient of variation was similar in the Early and Late hens (9.5% and 11.2%, respectively). The incidence of blind surges of LH (those not retrospectively associated with ovipositions) was not different between Early and Late laying hens (8.4% +/- 15.2% and 7.3% +/- 14.6%, respectively). In conclusion, in turkey hens, longer intervals and greater intra-hen variation between LH surges were associated with a poorer rate of egg production late in the reproductive period relative to early in the reproductive period.

Effect of selection for increased body weight and increased plasma yolk precursor on developmental stability in Japanese quail.

Developmental stability of several Japanese quail lines was measured by bilateral asymmetry. Lines included in the study were as follows: a randombred control (R1), sublines of R1 selected for increased (HW line) and decreased (LW line) 4-wk BW, and sublines of R1 selected for increased (HP line) or decreased (LP line) total plasma phosphorus (TPP; a measure of yolk precursor in the blood) at the beginning of lay. In sublines of the HW line, the males were selected for increased 4-wk BW and the females for increased (HW-HP line) or decreased (HW-LP line) TPP. The HW, LW, HP, and LP lines were in their 41st generation of selection and the HW-HP and HW-LP lines in their 31st generation of selection. The number of birds in each line and sex subgroup was 30. The adult breeders (28 to 32 wk of age) were weighed and killed, and bilateral measurements were made of shank length, width (laterally at the dew claw), and depth (perpendicular to the dew claw), face length, and pectoralis major and p. minor weights. Data on asymmetry was expressed for the right side minus the left side as signed and absolute differences. In order to correct for the correlation between trait size and asymmetry, relative asymmetry (RA) was obtained by dividing the absolute differences between sides by the average value of both sides and multiplying by 100. All lines differed in BW at 4 wk of age with the ranking HW > HW-LP > HW-HP > LP > R1 > HP > LW. Line rankings of adult breeders were similar, except the HP and LP lines did not differ from the R1 line and the order of ranking of the HW-HP and HW-LP lines was opposite that at 4 wk of age. Line differences in signed and absolute differences were significant for most bilateral traits. However, after adjustment for trait size, line differences in RA were less frequent. In general, there were few significant differences in RA for the R1 line versus the selected lines, even though inbreeding of the R1 line (19%) was less than half that of the selected lines (44 to 57%), suggesting that homozygosity did not influence developmental stability. Selection for increased or decreased BW had little influence on RA. Developmental stability tended to be higher in the lines (LP and HW-LP) selected for decreased TPP. The data indicated that bilateral asymmetry was not a good measure of developmental stability in the current study.

Effect of pH on endotoxin affinity for metal-ceramic alloys.

STATEMENT OF PROBLEM: Crevicular pH may modify bacterial endotoxin affinity for high-noble metal-ceramic alloys. PURPOSE: Porphyromonas gingivalis lipopolysaccharide (LPS) affinity for 3 metal-ceramic alloys at 3 different pH levels was compared in vitro by measuring adsorption to and release from the alloy surface. MATERIAL AND METHODS: Metallographically polished disks were fabricated from Pd-Ag-Sn, Au-Pd-Ag-Sn-In, and Au-Pd-In-Ga alloys. Clean disks were placed individually into 1 mL at pH 6.5, 7.0, or 7.5 phosphate-buffered saline solution containing 0.9 endotoxin units per square millimeter tritiated LPS (n = 3 disks per alloy-pH group). The disks were incubated for 24 hours at 37 degrees C before being transferred to LPS-free buffer and incubated, again for 24 hours at 37 degrees C, to evaluate elution. This transfer continued at 24-hour intervals up to 96 hours total elution incubation. Lipopolysaccharide adsorption to and elution from disks was determined through liquid scintillation spectrometry. Adsorption data were evaluated with a 2-way analysis of variance (alpha=.05) and the post hoc Tukey honestly significant difference test. RESULTS: Lipopolysaccharide adsorption values ranged from 0.48 +/- 0.04 EU/mm(2) for the Au-Pd-Ag-Sn-In alloy at pH 7.5 to 0.75 +/- 0.04 EU/mm(2) for the Pd-Ag-Sn alloy at pH 6.5. Alloy type (P=.0001) and environmental pH (P=.0001) significantly influenced adsorption. Adsorption to the Pd-Ag-Sn and Au-Pd-In-Ga alloys at pH 6.5, 7.0, and 7.5 were similar and decreased with increasing pH. In contrast, adsorption to the Au-Pd-Ag-Sn-In alloy was significantly less than to other alloys at pH 6.5 but did not differ at other pH levels. Lipopolysaccharide release from the alloy surface could not be detected. CONCLUSION: P. gingivalis LPS affinity for metal-ceramic alloys was modified by environmental pH. The degree of LPS adsorption depended on the composition and surface chemistry of each alloy.

Concentration change patterns of luteinizing hormone and progesterone and distribution of hierarchical follicles in normal and arrested laying turkey hens.

Young photosensitive turkey hens of a line selected for increased egg production (Egg line) were photostimulated with constant light [24 h light:0 h darkness] at 30 wk of age. Egg laying became arrested in 6 of 12 the hens after only 2 to 3 wk of laying. Ovarian morphology and changes in concentrations of plasma hormones [luteinizing hormone (LH), progesterone (P4), and estradiol-17beta (E2)] over 10 d of serial bleeding were compared between the arrested laying and normal laying hens. The number of ovarian follicles heavier than 1.0 g was much greater in arrested laying hens, and some of the arrested laying hens presented a polycystic ovarian follicle condition. The oviducts of the arrested laying hens were fully developed and were similar in weight to those of normal laying hens. In arrested laying hens the plasma concentration of LH was relatively low (1.72 +/- 0.30 ng mL(-1)) and without preovulatory surges. In normal laying hens the baseline concentration of LH was 2.60 +/- 0.71 ng mL(-1), and the interval between LH surges was 26.8 h. In the arrested laying hens, the plasma concentration of P4 was relatively high (4.66 +/- 1.28 ng mL(-1)) and without preovulatory surges. In normal laying hens the baseline concentration of P4 between surges was 1.76 +/- 0.24 ng mL(-1). Plasma E2 concentrations were not different between normal laying and arrested laying hens. In conclusion, ovulations and ovipositions ceased in the arrested laying hens, but the entrance of follicles into the follicular hierarchy and hierarchical growth continued, leading to an accumulation of numerous mature follicles in the ovary. In addition, some of the accumulated mature follicles might have resumed growing, leading to the formation of cystic ovarian follicles.

Preovulatory luteinizing hormone surge interval in old and young laying turkey hens early in the egg production period.

Egg production rate normally declines with duration of the reproductive period, but hen age and duration of the reproductive period are usually confounded. Initiation of egg production can be delayed in turkey hens with short-day lighting, allowing hen age to be separated from duration of the reproductive period. The objective of the present report is to determine if the interval between luteinizing hormone (LH) surges is different between old and young laying turkey hens during the peak of egg production. Turkey hens were given short-day lighting [6 h light (L):18 h darkness (D)] at 16 wk of age, and were photostimulated with 24L:OD (constant light) at 30 (young hens) or at 70 (old hens) wk of age. Egg production in the young hens started about 2 wk after they were photostimulated, but some of the old hens had started laying at 64 wk of age while under short-day lighting, and all old hens were laying after 1 wk of photostimulation. To monitor the interval between plasma LH surges at peak of production, hens were serially bled hourly for 240 h, starting about 6 wk after photostimulation. The interval of LH surges was not different between young (n = 5) and old (n = 10) laying hens. Not all LH surges were coincident with oviposition of eggs 1 to 2 d later (blind LH surges), and the percentage of young hens with at least one blind LH surge was higher than for old hens (60% of young hens and 10% of old hens). The baseline concentration of LH was not different between the young and old laying hens. In conclusion, the interval between LH surges, baseline concentration of LH, and amplitude of LH surges were not related to age of the hens during the peak rate of lay.

Collagen characteristics and organization during the progression of cholesterol-induced atherosclerosis in Japanese quail.

This study reports the concentration of collagen and its hydroxypyridinoline crosslinks, collagen fibril organization in the dorsal aortas, and systolic blood pressure during the progression of atherosclerosis in Japanese quail selected for cholesterol-induced atherosclerosis. The quail were placed on either a control or 0.5% cholesterol-added diet at approximately 16 weeks of age. The concentration of total collagen did not change in the control arteries during the course of the study, whereas at 5 and 10 weeks of cholesterol feeding, collagen levels decreased in the cholesterol-fed birds. Hydroxypyridinoline concentration increased during the duration of the study in the cholesterol-fed birds and by 15 and 20 weeks of cholesterol feeding, levels were significantly increased over those observed in the control arteries. Transmission electron microscopy showed changes in the organization of collagen fibrils. Increased systolic blood pressure was noted beginning at 10 weeks of cholesterol feeding, which is suggestive of other systemic changes induced by hypercholesterolemia. These results demonstrated remodeling of the collagen component of the dorsal aorta extracellular matrix during the progression of atherosclerosis and are suggestive of other systemic cardiovascular system changes.

Frequency of luteinizing hormone surges and egg production rate in turkey hens.

Whether the interval between preovulatory surges of LH was different between lines of turkey hens with either poor (RBC3 line, peak at 55%) or excellent rate of egg production (Egg line, peak at 85%) was examined. Laying hens were cannulated and bled hourly for 10 days at peak of production. A constant light photoschedule was used to avoid diurnal masking of innate circadian rhythms. The mean interval between LH surges in the RBC3 line was longer than in the Egg line and had a higher coefficient of variation. A few longer LH surge intervals (72 h) were found in some RBC3 line hens (2 of 7 hens), but none were found in Egg line hens (0 of 11 hens). All progesterone (P4) surges were coupled with LH surges, but not all LH-P4 surges were coupled with ovipositions (blind LH-P(4) surges). The percentage of blind LH-P4 surges was not different between lines. The baseline concentration of LH was higher in Egg line than RBC3 line hens, but LH surge amplitude, and surge duration were not different. The baseline and surge amplitude concentrations of P4 were not different between lines, nor was the concentration of estradiol-17beta. The longer interval between LH surges was the major factor tested that was associated with the poorer egg production rate in RBC3 line hens in comparison to Egg line hens. A higher incidence of blind LH surges further contributed to lower egg production in RBC3 line turkey hens.

Effects of environmental lighting on early semen production and correlated hormonal responses in turkeys.

Recent work at our institution on lighting turkey males for semen production and correlated changes in plasma luteinizing hormone (LH) and testosterone (T) are summarized in this paper. In sexually mature males, both LH and T are secreted in pulses, with a pulse of LH about 10 min prior to a pulse of T. Pulses of LH and T occurred about every 2 h and were equally distributed between the light (L) and dark (D) portions of a 14 h L:10 h D d. The pattern of secretion and overall concentrations of LH and T were not affected by intermittent photoperiod lighting (1 L:2 D, 8 x d) in comparison to continuous photoperiod lighting (14 L:10 D) lighting. Pulses of LH or T were not entrained by L or D with the intermittent or continuous lighting treatment. To study the interaction of age and lighting treatment, males were exposed to one of two lighting treatments: long-day photoperiods (16 L:8 D) d(-1) from 10 to 12 or 29 wk of age (WOA) (Treatment LDLD) or short-day photoperiods (6 L:18 D d(-1) from 10 or 12 to 29 WOA, then long-day photoperiods (Treatment SDLD). Males in the LDLD treatment attained puberty earlier (25 WOA) than those in the SDLD treatment. In the later treatment, most of the males attained puberty after 29 WOA. Both LH and T were low until 18 WOA in the LDLD males, then both increased to adult levels over the next 2 to 3 wk. In the SDLD males, LH and T were lower than in the LDLD males until 48 h after switching to long-day photoperiods, when both were transiently higher before declining to lower adult levels by 35 WOA. Secretory patterns of LH and T were estimated at 13, 23, and 35 WOA, under both lighting treatments. At 13 WOA, LH and T were secreted in pulses, but levels of both hormones were low and not different between lighting treatments, and none of the birds (0/4) in either treatment were producing semen. At 23 WOA, LH and T were secreted in robust pulses, with the LDLD males having higher concentrations of LH and T than the SDLD males. At 23 WOA, most of the males in the LDLD group (3/4) but none in the SDLD group (0/4) were producing semen. At 35 WOA, 6 wk after photostimulation of the SDLD group, all males (4/4) in both groups were producing semen, and LH and T were at adult levels. However, fewer pulses of T were noted for males in the SDLD treatment.

5-Hydroxytryptamine(7) receptor activation decreases slow afterhyperpolarization amplitude in CA3 hippocampal pyramidal cells.

The 5-hydroxytryptamine(7) (5-HT(7)) receptor was originally defined by molecular biology techniques. The 5-HT(7) receptor protein and mRNA are found in brain areas, such as the CA3 subfield of the hippocampus, that are involved in various neuropsychiatric disease states. No functional response has previously been attributed to activation of the 5-HT(7) receptor in any of these brain areas. Calcium spike-induced slow afterhyperpolarizations (sAHP) were recorded from CA3 hippocampal pyramidal cells using intracellular recording techniques in a brain slice preparation maintained in vitro. A concentration-dependent inhibition of the sAHP amplitude was obtained when 5-HT was used as the agonist. To identify whether the 5-HT(7) receptor was one of the receptors mediating the inhibition of the sAHP amplitude, 5-HT agonists and antagonists were tested in the presence of WAY-100635 and GR-113808 to block 5-HT(1A) and 5-HT(4) receptor activation, respectively. The rank order potency of the agonists was 5-carboxyamidotryptamine (5-CT) > 5-HT > 5-methoxytryptamine (5-MeOT). Other agonists with high affinity at 5-HT(2), 5-HT(3), 5-HT(1B), 5-HT(1D), or 5-HT(6) receptors did not produce any response when tested at 10 microM. Ritanserin, mesulergine, and SB-269770 were competitive antagonists of the 5-CT inhibition of sAHP amplitude, with affinity (pA(2)) values of 6.8, 7. 9, and 8.8, respectively. Methiothepin was also an effective antagonist but was insurmountable. Other antagonists with affinity for the 5-HT(2), 5-HT(3), or 5-HT(6) receptor had no effect. Based on the rank order potency of the agonists and antagonists, one of the receptors that mediates the decrease in sAHP amplitude in CA3 hippocampal pyramidal cells was concluded to be the 5-HT(7) receptor.

Effect of selection for increased body weight on mitogenic responses in turkeys.

Mitogenic responses were examined for purified peripheral blood mononuclear cells (PBMC) and whole blood from individuals in a line (F) of turkeys selected for increased 16-wk BW and its corresponding randombred control (RBC2). The PBMC were isolated by centrifugation over Histopaque-1077 density gradient and tested for mitogenic responses to concanavalin A (Con A; 25 microg/mL) and phytohemagglutinin (PHA)-M; 100 microg/mL). For the whole blood assay, 6-wk-old poults from both lines were injected with inactivated Pasteurella multocida. Heparinized blood samples were collected prior to injection (0 d) and at 2, 4, 7, and 14 d postinjection. The diluted whole blood was then tested for the mitogenic responses to Con A (25 microg/mL) and PHA-M (25 microg/mL). The cultures were then pulsed with 3H-thymidine, and incorporation was measured using a liquid scintillation counter. There was a line difference in the mitogenic responses to Con A for PBMC and whole blood assays, but no line difference was observed in the response to PHA-M for both assays. For the purified PBMC assay, the F line had a lower response than its randombred control line (P < or = 0.05) to Con A expressed as either cpm or a stimulation index (SI; ratio of cpm for stimulated cells to the cpm for unstimulated cells). For the whole blood assay, the F line had generally lower SI values in the responses to Con A than the RBC2 line, with differences being significant at 0 and 2 d postinjection (P < or = 0.01) and at 14 d postinjection (P < or = 0.05). Genetic selection for increased BW might have affected the lymphoblastogenic potential of Line F that could affect disease resistance.

Ontogeny of luteinizing hormone and estradiol secretion in turkey hens exposed to different photoperiods from hatch to sixty weeks of age.

Changes in concentrations of plasma luteinizing hormone (LH) and estradiol-17beta in turkey hens were measured during development utilizing stimulatory and nonstimulatory lighting treatments. All hens were maintained under 24 h light (L) from hatch to 3 wk of age, then 16L:8 dark (D) to 10 wk of age. From 10 wk of age, three lighting treatments were used: 1) 16L:8D from 10 to 60 wk of age (Treatment LD); 2) 6L:18D from 10 to 60 wk of age (Treatment SD); and 3) 16L:8D from 10 to 20 wk of age, 6L:18D from 20 to 30 wk of age, and then 16L:8D from 30 to 60 wk of age (Treatment SD-LD). Measurements of plasma LH and estradiol-17beta concentrations were based on weekly blood samples. Similar patterns of LH were observed in all treatments before 24 wk of age. The concentrations of LH were high at hatch then declined to low levels at 10 wk of age and rebounded to high levels at 18 wk of age before declining to low levels at about 24 wk of age. Low concentrations of LH were then maintained for hens on all treatments but were slightly higher in hens on Treatment SD from 35 to 60 wk of age. A transitory increase in LH, lasting about 3 wk, occurred for hens on Treatment SD-LD after photostimulation. The concentrations of estradiol-17beta were low and stable for hens on all treatments when they were not laying but were elevated about 2 wk prior to and during egg laying. All hens on Treatments LD and SD-LD laid eggs; no hens on Treatment SD laid eggs to 60 wk of age. It was concluded that 1) changes in plasma LH and estradiol-17beta were age related before about 24 wk of age, 2) turkey hens may not be photorefractory at hatch and can lay without juvenile exposure to SD photoperiods, and 3) LD photoperiods after about 20 wk of age are necessary for initiation of egg production in turkey hens before 60 wk of age.

Effect of divergent selection for total plasma phosphorus on plasma and yolk very low density lipoproteins and plasma concentrations of selected hormones in laying Japanese quail.

Japanese quail lines were divergently selected over 32 generations for laying hen plasma yolk precursor, as measured by total plasma phosphorus (TPP). The high (HP) and low (LP) lines were developed from a randombred control population (R1) that was maintained without conscious selection. The purpose of the present study was to characterize the composition of very low density lipoproteins (VLDL) in laying Japanese quail hens (VLDLy) and the concentration of selected hormones in laying hens from the HP, LP, and R1 lines. The changes in TPP because of genetic selection in the Japanese quail lines were associated with large alterations in plasma VLDLy concentration (HP > R1 > LP), but only minor changes in lipid composition and size (HP > LP = R1; P< or =0.01) of plasma VLDLy particles. Basal plasma levels of hormones associated with reproduction and lipid metabolism were also different among lines, with luteinizing hormone (LH) ranking HP >R1 = LP and triiodothyronine (T3), thyroxine (T4), and 17beta-estradiol ranking HP > R1 > LP (P< or =0.05). The results suggest possible increased rates of hepatic lipogenesis, hepatic VLDLy assembly and secretion, and plasma VLDLy concentration in association with increases in concentrations of plasma LH, T3, T4, and 17beta-estradiol. Concentrations of total lipids in yolk VLDL were not different among lines, and only minor line differences in the concentration of different classes of yolk VLDL neutral lipids were detected. The data indicate a preferential uptake of a specific plasma VLDLy subpopulation into rapidly growing ovarian follicles, resulting in a constant composition of yolk VLDL of laid eggs among lines of Japanese quail with large differences in plasma VLDLy concentration.

Effect of feed withdrawal or challenge with Pasteurella multocida on growth, blood metabolites, circulating growth hormone, and insulin-like growth factor-I concentrations in eight-week-old turkeys.

The daily effects of feed withdrawal or a bacterial disease (Pasteurella multocida; PM) challenge was studied in a slow-growing line of turkeys. The following groups (n = 6 birds/group) were sampled for up to 13 d: untreated control (CON), 4-d feed withdrawal followed by refeeding (FAST), a group that succumbed within the first 2 to 3 d after PM challenge (E-DEAD), a group that succumbed 8 to 9 d after PM challenge (L-DEAD), a group that survived the PM challenge (SUR), and a group treated with both PM challenge and 4-d feed withdrawal followed by refeeding (FAST/CHAL). Daily feed intake and BW gains were markedly reduced in the E-DEAD and L-DEAD groups immediately and 3 d after PM challenge, respectively. Feed intake and BW gain between CON and SUR groups of turkeys were not different throughout the trial. The turkeys in the FAST group followed the expected feed withdrawal and refeeding patterns for feed intake and BW loss or gain. The FAST/CHAL turkeys consumed the minimal amount of feed to maintain BW after refeeding. Plasma uric acid sharply increased 1 d prior to death in both E-DEAD and L-DEAD groups of turkeys. Plasma uric acid also increased each consecutive day during fasting in the FAST and FAST/CHAL groups of turkeys. Plasma growth hormone was measured in only the CON and FAST groups and increased from about 40 to 85 ng/mL in the FAST group during fasting but returned to control levels within 1 d of refeeding. Circulating plasma insulin-like growth factor-I (IGF-I) decreased from about 17 to 5 ng/mL in the PM-challenged (E-DEAD, L-DEAD, and FAST/CHAL groups) and FAST groups. The concentration of IGF-I returned to prefeed withdrawal levels within 3 d of refeeding the FAST group of turkeys. It was concluded that 1) turkey poults that were not susceptible to the PM challenge generally maintained physiological functions at control bird levels, 2) susceptible turkey poults generally exhibited depressed feed intake and BW gains, and 3) poults challenged with both feed withdrawal and PM treatment responded differently than poults challenged with either feed withdrawal or challenge with PM. The depletion of energy intake and mobilization of energy stores in susceptible poults might have contributed to the rate at which PM caused the poults to die.

Genetic relationship among lines and smooth muscle and ovarian follicular development within lines of Japanese quail in two long-term selection studies.

Smooth muscle tumor and ovarian follicular development were studied in lines of Japanese quail selected for increased 4-wk BW (HW, P, and T) and their randombred controls (C and R1). The lines studied were from long-term selection studies at The Ohio State University (HW and R1) and The University of Georgia (P, T, and C). To study the genetic relationship among the lines in the two selection studies, the C, P, HW, and R1 lines were DNA-fingerprinted by digestion of the DNA with the HaeIII restriction enzyme and using Jeffreys' 33.6 probe. The BW of females at 4 wk of age and at the end of a 240-d egg production period were similar for the C and R1 lines. The BW of the selected lines was ranked P > T > HW for both measurements. Smooth muscle tumors were found in the oviducal ligaments adjacent to the magnum. A greater percentage of hens from the BW-selected lines had smooth muscle tumors of greater weight than the randombred control lines, which did not differ in tumor incidence or weight. The P and T lines had a greater incidence of multiple-lobed tumors than the HW line. Based on bandsharing (BS) of DNA fingerprints, the Georgia and Ohio lines did not appear to be closely related, suggesting that, perhaps, the smooth muscle tumors in the BW-selected lines in the two studies might have resulted from pleiotrophic effects of genes affecting growth or to genes closely linked to the growth genes. The BW-selected lines in both selection studies had more ovarian follicles in rapid development, which were of greater weight, than the randombred control lines. The HW line had a larger number of ovarian follicles in rapid development than the P and T lines. The percentage of hens with atretic follicles was greater in the BW-selected lines. The results of the present study suggest that the effect of BW selection on ovarian follicular development may occur early in selection (within the first 30 generations) and is not influenced by additional genetic changes in BW.