An analysis of the pattern of feeding in the Costa Rican weevil, Exopthalmus jekelianus, on the tropical tree, Cedrela odorata

Feeding patterns were recorded and analysed for adult female weevils, Exopthalmus jekelianus (White) (Coleoptera: Curculionidae), feeding on Central American mahogany, Cedrela odorata L., in the field in Costa Rica. The study forms part of an investigation into the relationship between feeding patterns and the fine-scale variation in leaf chemistry occurring within the host plant. The weevils’ feeding patterns were the simplest in temporal structure of any reported to date for an insect herbivore. Weevils spent an average of only 3% of their time feeding during the 10-h observation periods. Meals lasted an average of 2.8 min and occurred at a mean intermeal interval of 84 min. The feeding patterns gave the appearance of a short-term rhythm underlying the onset of feeding (as has been found in locusts and caterpillars), although there were insufficient meals taken by individuals over the 10-h period to test this suggestion. Meals were notable in apparently lacking intrameal pauses and also commencing without preliminary sampling behaviours, such as palpating or biting. Whether the combination of short, infrequent meals, ingested without pauses and not preceded by sampling behaviour, represents an adaptation reducing apparency to natural enemies, or else simply reflects low nutritional needs, is discussed. Correlations between meal durations and following and preceding intermeal intervals suggested that variation in intermeal intervals stemmed largely from variation in meal duration, not vice versa, with variation in meal duration resulting from an external influence such as leaf nutritional and/or allelo-chemistry. The latter suggestion is currently being tested.     

Timing of insemination relative to ovulation in pigs: effects on sex ratio of offspring

The objective of the present study was to identify effects of the interval between insemination and ovulation in pigs on the sex ratio and sex ratio dispersion of offspring. Crossbred sows that had farrowed 2 to 9 litters were weaned (Day 0) and came into estrus between Days 3 and 7 after weaning. Ultrasonography was performed every 6 h, from 12 h after the onset of estrus until ovulation had been observed. The sows were inseminated once at various intervals from the onset of estrus. At farrowing, the numbers of viable piglets and dead piglets were recorded per sow. In four 12-h intervals between insemination and ovulation (36 to 24 h before ovulation, 24 to 12 h before ovulation, 12 to 0 h before ovulation and 0 to 12 h after ovulation), the total number of piglets was (mean+/-SEM) 10.8+/-1.2 (n=15); 13.4+/-0.7 (n=23); 13.2+/-0.9 (n=21); and 12.1+/-1.0 (n=16), respectively (P>0.05). The percentage of male piglets per litter in the four 12-h intervals was 52.1+/-3.6, 50.5+/-2.7, 54.9+/-2.8 and 47.8+/-4.5, respectively (P>0.05). Sex ratio was not influenced by litter size (P>0.05), and its distribution was normally dispersed (i.e., as expected under a binomial distribution) in all 4 intervals between insemination and ovulation (P>0.05).     

Provisioning and growth rates of nestling Fulmars Fulmarus glacialis: stochastic variation or regulation?

The pattern of chick feeding in the Fulmar Fulmarus glacialis at St Kilda, Scotland, was examined by repeated weighing of chicks throughout 14 consecutive days during the first half of the chick-rearing period in 1994. After correcting for metabolic weight losses, the sizes of positive mass increments between weighings were used to assess meal sizes and feeding frequency for each chick. Individual meals fed to chicks averaged 80.8 g (s.d. ± 21.0 g), or approximately 10% of adult mass. Each chick received 0 to 4 meals per day, with an average of 1.9 meals per chick per day, giving an average interval of around 25 h between meals delivered by each parent. The distribution of time intervals between feeds for each chick (whether single or double meals) followed a negative exponential function with a maximum value of 80 h. These results are not compatible with the idea that the purpose of large fat deposits in procellariiform chicks is to guarantee survival over long intervals between feeds. Over 14 days, the chicks' mean daily food requirements for zero-growth increased from 98 g to 160 g. This corresponded with an increase in feeding frequency but not meal size. Chicks with lower scores for body condition after feeding by both parents received more meals during the subsequent 16 h and had shorter intervals to the next feed, indicating that adults regulated feeding frequency in accordance with chick condition at the previous feed. This does not agree with the hypothesis that lipid accumulation by nestling Procellariiformes is a response to stochastic variation in food delivery associated with an absence of regulation. In view of the diversity of growth and feeding patterns present among the Procellariiformes, it is possible that lipid accumulation in this group does not have a unitary explanation.     

Membrane dielectric responses of human T-lymphocytes following mitogenic stimulation

Human peripheral blood T-lymphocytes, normally resting at the G0 phase, were stimulated with phytohemagglutinin (PHA) and interleukin-2 (IL-2) to induce the cell division cycle. The cells were examined at 24-h intervals for up to 96 h by flow cytometry to determine cell cycle distributions and by electrorotation to determine dielectric properties. The average membrane specific capacitance was found to vary from 12 (+/-1.5) mF/m2 prior to stimulation to 10 (+/-1.5) and 16 (+/-3.5) mF/m2 at 24 and 48 h after stimulation, respectively, and to remain unchanged up to 96 h after stimulation. Scanning electron microscopy studies of the cells revealed an increased complexity in cell membrane morphology following stimulation, suggesting that the observed change in the membrane capacitance was dominated by the alteration of cell surface structures. The average electrical conductivity of the cell interior decreased from approximately 1.1 S/m prior to stimulation to approximately 0.8 S/m at 24 h after stimulation and showed little change thereafter. The average dielectric permittivity of the cell interior remained almost unchanged throughout the course of the cell stimulation. The percentage of T-lymphocytes in the S and G2/M phases increased from approximately 4% prior to stimulation to approximately 11 and approximately 34% at 24 and 48 h after stimulation, respectively. The large change in membrane specific capacitance between the 24 and 48 h time period coincided with the large alteration in the cell cycle distribution where the S and G2/M populations increased by approximately 23%. These data, together with an analysis of the variation of the membrane capacitance during the cell cycle based on the cell cycle-dependent membrane lipid accumulation, show that there is a correlation between membrane capacitance and cell cycle phases that reflects alterations in the cell plasma membrane.     

Circadian oscillations of thyroid hormones and insulin in the serum of fasting rats

Adult male Wistar rats adapted to a 12:12 h light:dark regimen, fed or after a 24- or 48-h fast, were decapitated at 3-h intervals during a single day. They were deprived of food at day-time intervals ensuring that on decapitation they had fasted for the same length of time, i.e. 24 or 48 h. Thyroid hormones, insulin and glucose concentrations were determined in their serum. Fasting did not significantly affect circadian thyroxine, triiodothyronine and reverse triiodothyronine rhythms compared with the findings in fed animals; 24, but not 48 hours' fasting led to a shift in the acrophase of circadian insulin and glucose oscillations compared with fed rats. The maintenance of original circadian thyroid hormones and insulin rhythm in rats which fasted for short lengths of time testifies to a dependence of the stimulus on the time of day.     

The structure of feeding behavior in the colorado potato beetle,Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Feeding behavior, in an ad libitum situation on potato plants in the laboratory, was continuously observed for approximately 7 h/day on 2 successive days for 18 adult femaleLeptinotarsa decemlineata. Additional behaviors were also recorded including resting, walking, biting, local movements, grooming, defecating, and regurgitating. These data were used to calculate a time budget for the various behaviors. The feeding data were analyzed to describe the structure of feeding for young adult females on their normal host plant. The criterion for a meal (minimum intermeal interval) was determined to be 286 s. This criterion was used to distinguish between intra- and intermeal interruptions in feeding for all subsequent analyses. Meals taken from leaves that were young, medium aged, or old did not differ, but on average beetles took 60% of their meals from young leaves. Meal size and meal duration were equally good predictors of when a meal would end. Feeding from stems was a prominent feature for most beetles. The stem meals had much longer durations than leaf meals, but stem feeding did not affect subsequent leaf feeding. The structure of feeding by these beetles is compared with that found in other insects, especiallyLocusta migratoria.     

Cholecystokinin-33 inhibits meal size and prolongs the subsequent intermeal interval

There are various forms of the satiety gut-brain peptide cholecystokinin (CCK), a short, widely utilized form or CCK-8, and a long, putatively more effective form or CCK-33. The issue of which of these forms is a more effective satiety peptide is not resolved. Here, we compared the satiety responses, including the sizes of the first three meals (MS) and intermeal intervals (IMI) as well as their calculated satiety ratios (SR), evoked by both peptides. CCK-8 and 33 (1, 3 and 5 nmol/kg, i.p) reduced the size of the first meal similarly, only CCK-33 prolonged the first IMI and increased SR and both peptides failed to affect second and third MS and IMI. As such, CCK-33 is a more effective satiety peptide than CCK-8. The current results confirm previous findings which showed that both peptides reduce food intake by inhibiting meal size, whereas only CCK-33 reduces food intake by prolonging the intermeal interval.     

Plasma ghrelin levels and hunger scores in humans initiating meals voluntarily without time- and food-related cues

Ghrelin is an orexigenic hormone that is implicated in meal initiation, in part because circulating levels rise before meals. Because previous human studies have examined subjects fed on known schedules, the observed preprandial ghrelin increases could have been a secondary consequence of meal anticipation. A causal role for ghrelin in meal initiation would be better supported if preprandial increases occurred before spontaneously initiated meals not prompted by external cues. We measured plasma ghrelin levels among human subjects initiating meals voluntarily without cues related to time or food. Samples were drawn every 5 min between a scheduled lunch and a freely requested dinner, and hunger scores were obtained using visual analog scales. Insulin, glucose, fatty acids, leptin, and triglycerides were also measured. Ghrelin levels decreased shortly after the first meal in all subjects. A subsequent preprandial increase occurred over a wide range of intermeal intervals (IMI; 320-425 min) in all but one subject. Hunger scores and ghrelin levels showed similar temporal profiles and similar relative differences in magnitude between lunch and dinner. One subject displayed no preprandial ghrelin increase and was also the only individual whose insulin levels did not return to baseline between meals. This finding, along with a correlation between area-under-the-curve values of ghrelin and insulin, suggests a role for insulin in ghrelin regulation. The preprandial increase of ghrelin levels that we observed among humans initiating meals voluntarily, without time- or food-related cues, and the overlap between these levels and hunger scores are consistent with a role for ghrelin in meal initiation.     

Suppression of food intake and body weight gain by naloxone in rats

The effect of acute and chronic administration of naloxone on food acquisition and weight gain in rats was studied in 3 experiments. One injection of a sparingly-soluble salt of naloxone in slow-release vehicle markedly lowered mean food intake over that of control rats injected with the vehicle only. Mean body weight of the naloxone-injected rats was significantly lower than that of the control group for one week.Repeated evening injections (2000 h) of naloxone hydrochloride in saline tended to reduce the night-time feeding below control levels throughout the 10-day period of naloxone administration. Food intake was significantly lower in the 4- and 8-h periods after the first injection of naloxone than that on the preceding saline control night. The initial decreases were offset by increased day-time feeding so that total daily food intake was not significantly altered over the 10 days. When saline was substituted for naloxone, food intake increased.Rats given naloxone following 24 h of fasting consumed significantly less food and gained less weight during 4 h of access to food compared to those receiving saline. After a 48-h fast naloxone-treated rats also gained significantly less body weight than those given saline, but the reduction in food intake was not statistically significant. These results suggest the possibility that endorphins may have a modulating effect on feeding activity.     

Naphthol-yellow-S protein content of individual rat hepatocytes as related to food intake and short-term starvation

With regard to the protein content, as analysed cytophotometrically, of hepatocytes from rats kept under a 12L 12D photoperiod (photophase 7:00-19:00), the following facts have been established: 1) Hepatocytes of different classes of ploidy all demonstrate, more or less equally, daily variations in protein content and also its reduction after 24-h fasting. 2) With computer analysis of data obtained at eight time points during a period of 24 h, a sinusoidal curve of the protein content of individual mononuclear tetraploid hepatocytes throughout the day could be demonstrated with a maximum at 6:20 and a minimum at 18:20. 3) Animals, fed with meals via a dispensing machine from 23:00 to 24:00 only, show a similar sinusoidal curve but with higher amplitude, and a virtually identical mean value as those fed ad libitum. The maximum was found at 10:40, revealing a time lag of 12 h after food intake, the minimum at 22:40. 4) Trained animals deprived of food during the standardized feeding time revealed a moderate reduction of their hepatocyte protein content in the first 6 h, then a 6-h period with a steep fall followed by a slower reduction. After 24 h, the mean hepatocyte protein mass had decreased to 72% of that at the commencement of fasting at 23:00.     

Extent of digestion affects the success of amplifying human DNA from blood meals of Anopheles gambiae (Diptera: Culicidae)

The success of distinguishing blood meal sources of Anopheles gambiae Giles through deoxyribonucleic acid (DNA) profiling was investigated by polymerase chain reaction (PCR) amplification at the TC-11 and VWA human short tandem repeats (STR) loci. Blood meal size and locus had no significant effect on the success of amplifying human DNA from blood meals digested for 0, 8, 16, 24 and 32 h (P = 0.85 and 0.26 respectively). However, logistic regression found a significant negative relationship between time since ingestion and the success probability of obtaining positive PCR products among meals digested for between 8 and 32 h (P = 0.001). Approximately 80% of fresh blood meals were successfully profiled. After 8 h, the proportion of blood meals that could be successfully profiled decreased slowly with time after ingestion, dropping to below 50% after approximately 15 h. There was no significant difference in the success of amplifying human DNA from blood meals of mosquitoes killed at time 0 and 8 h after ingestion (P = 0.272).     

Concentrations of LH, oestradiol-17 beta and progesterone in the peripheral plasma of swamp buffalo cows (Bubalus bubalis) around the time of oestrus

Peripheral plasma concentrations of LH, oestradiol-17 beta and progesterone were measured in 13 mature swamp buffalo cows at 4-h intervals from 36-40 h before until 36-40 h after the onset of oestrus. Mean LH concentrations increased sharply to a peak of 35 ng/ml and returned to basal levels of 5 ng/ml within a 12-h period beginning soon after the onset of oestrus. Mean oestradiol-17 beta concentrations were within the range 9-13 pg/ml from 36-40 h before until 12-16 h after the onset of oestrus, and within the range 7-9 pg/ml thereafter. Progesterone concentrations remained around 0.1 ng/ml throughout the sampling period. There were no significant differences in hormone concentrations or changes between cows that conceived and those that did not conceive to artificial insemination 12-24 h after onset of oestrus.     

An analysis of feeding patterns in the adult pig

Feeding behavior has been analyzed in Large-White and Chinese pig breeds. Maximally automatized apparatuses, especially adapted to animal size, were used. Besides the usual parameters measured such as food intake, meal size, meal duration, meal frequency, intermeal intervals and postprandial correlation, these apparatuses also permitted us to measure the rate of intake during the meal. This rate was constant throughout the meal in ad libitum conditions and after 24-hour deprivation. A positive correlation between meal size and length of the postmeal interval was found in only half of the animals. During this work, we began to study the mechanisms initiating food intake.     

Altered Patterns of Protein Phosphorylation and Synthesis Caused by Methyl Mercury in Cerebellar Granule Cell Culture

In the preceding report we demonstrated a dose-dependent increase in 32P-phosphoprotein labeling after 24-h exposure of cultured cerebellar granule neurons to methyl mercury (MeHg), a response that was not observed in glial cultures. In the present study we have examined 32P-labeled phosphoproteins by two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. At concentrations of 0.5 and 1 microM, which were not extensively cytotoxic, MeHg enhanced phosphorylation of numerous acidic proteins, particularly a cluster of proteins with Mr approximately 28,000 and pI approximately 5.7-5.9 (pp 28/5.7-5.9) and a protein with Mr approximately 58,000 and pI approximately 5.6. The pp28 cluster displayed considerable two-dimensional pattern variability from one experiment to the next, suggesting susceptibility to subtle structural modifications. Time course studies revealed that increased 32P phospholabeling of pp28/5.7-5.9 was detectable after 12-h exposure to 3 microM MeHg and reached values of 300-500% of control by 24 h. These studies also showed that among the 21 proteins analyzed by two-dimensional densitometry, 32P phospholabeling of four proteins increased by 20-50% and of two proteins decreased by 20-50% after 24-h treatment. However, exposure to 10 microM MeHg produced stimulation of pp28/5.7-5.9 32P phospholabeling within 2 h. Under these conditions a relatively high stimulation (sevenfold) of pp28/5.7 phospholabeling occurred, while pp28/5.9 32P phospholabeling was only moderately (5-20%) enhanced. 35S and 32P double-label analysis of cells treated with 0, 0.5, and 1 microM MeHg indicated specific stimulation of 32P phospholabeling of these proteins without increased polypeptide synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationships between LH, FSH and prolactin secretion and reproductive activity in the weaned sow

Blood samples were collected from primiparous sows via indwelling jugular cannulae at 15-min intervals for 12 h before and for 24 h (2 sows) or 48 h (10 sows) after weaning and then every 4 h until behavioural oestrus. Weaning to oestrus intervals ranged from 3 to 10 days and 2 sows showed no signs of oestrus and had not ovulated by Days 11 and 16 after weaning. Prolactin concentrations in plasma decreased significantly (P less than 0.001) and reached basal levels 1-2 h after weaning in all sows whilst plasma progesterone concentrations remained basal until approximately 30 h after the preovulatory LH surge in sows that ovulated. Elevated concentrations of prolactin or progesterone during the post-weaning period were, therefore, not responsible for delayed restoration of cyclicity. Overall, mean LH concentrations rose significantly (P less than 0.001) from 0.22 +/- 0.02 during the 12-h period before weaning to 0.38 +/- 0.03 ng/ml during the 12-h post-weaning period. After weaning, pulsatile and basal LH secretions were markedly increased for sows that showed an early return to oestrus (less than or equal to 4 days) compared with sows showing a longer weaning to oestrus interval but a correlation did not exist between either of these LH characteristics and the time taken to resume cyclicity. Mean LH concentrations before weaning were, however, inversely related (r = -0.649; P less than 0.05) to the weaning to oestrus interval. Overall, mean FSH concentrations rose significantly (P less than 0.001) from 151.1 +/- 6.2 (s.e.m.) ng/ml in the 12-h period immediately before weaning to 187.7 +/- 9.7 ng/ml in the subsequent 12-h period but there was no correlation between FSH concentrations, before or after weaning, and the interval from weaning to oestrus. However, a significant correlation was apparent between ovulation rate and peak concentrations of the rise in FSH after weaning (r = 0.746; P less than 0.05) and overall mean FSH values (r = 0.645; P less than 0.05). It is concluded that both LH and FSH concentrations in peripheral blood rose in response to removal of the suckling stimulus at weanling. The increase in LH pulse frequency associated with weaning was not directly related to the weaning to oestrus interval although a specific pattern of LH secretion was observed in sows showing an early return to oestrus (less than or equal to 4 days).(ABSTRACT TRUNCATED AT 400 WORDS)     

The effect of various photoperiods on daily oscillations of serum corticosterone and insulin in rats.

The effect of various photoperiods on circadian rhythms of chosen parameters was investigated in laboratory rats. SPF male Wistar rats were adapted for six weeks to artificial light-dark cycles (LD 8:16, 12:12, 16:8). The light was switched on at 07.00 h in all regimens. The rats were killed at 3-hour intervals within 24 h, the serum concentration of corticosterone, insulin, glucose, food and water intake was determined. The external and computative acrophases of corticosterone varied in every photoperiod being dependent on the duration of light, the mesor values decreased in LD 16:8 in comparison with other photoperiods. The external acrophase of insulin was located 4 h after light onset in LD 8:16 and 12:12, in LD 16:8 one hour before light onset. The mesor values were approximately equal in all photoperiods. The circadian rhythms of glucose were similar in all regimens. Circadian variation of food and water consumption culminated at the same time in all regimens, the amount of food consumed in light increased with the light duration. Various photoperiods remarkably influenced circadian oscillations of corticosterone and in part food and water intake which could be considered as photoperiodic traits.     

Defective diurnal changes of food intake, plasma glucose and insulin in rats with a transplantable islet cell tumour

Subcutaneous implantation of small fragments of a radiation-induced transplantable rat insulinoma into the subscapular region of 16- to 17-week-old male NEDH rats resulted, over a 22-day period, in the progressive development of marked hyperinsulinaemia and severe hypoglycaemia, despite a compensatory increase in food intake. Diurnal changes were examined at 3-hourly intervals for 24 h in control rats and tumour-bearing rats at 20-21 days after transplantation. The control animals exhibited distinct diurnal changes of food intake, glucose and insulin concentrations. Food intake was greatest between 17.00 and 23.00 h; plasma insulin was greatest between 20.00 and 23.00 h, and plasma glucose was raised at 20.00, 02.00 and 05.00 h, compared with the other times. In contrast, insulinoma-bearing rats displayed no diurnal changes other than a small decrease in food intake between 05.00 and 11.00 h. Plasma glucose and insulin concentrations were significantly different from control rats at all times, and food intake was significantly increased between 23.00 and 17.00 h. These observations demonstrate that the transplantable insulinoma not only causes hyperinsulinaemia and hypoglycaemia but results in hyperphagia and defective diurnal changes of food intake, plasma glucose and insulin concentrations. Interruption of nutrient intake by withdrawal of food for 6 h exacerbated the hypoglycaemia of insulinoma-bearing rats leading to coma.     

24-hour pattern of work-related injury risk of French firemen: nocturnal peak time

The first aim of the study was to assess clock-time patterning of work-related injuries (WRIs) of firemen (FM) of Sa?ne et Loire-71 (France) during the 4-yr span of 1 January 2004 to 31 December 2007. FM of this service are legally required to log every WRI and seek its evaluation by the medical service, whether the WRI was the result of worksite duties or exercise/sport activities at the station. WRI was defined specifically as a (nonexercise, nonsport, and nonemotional/stress) work-associated trauma, verified both by log book and medical records. For the corresponding years, the 24-h pattern of emergency calls (Calls) plus road traffic (Traffic) on the main roads of the service area was also assessed. Relative risk (R) of WRI was calculated as the quantity of WRIs/h divided by the quantity of Call responses/h?×?1000, which takes into account the number of at-risk FM/unit time, since each dispatched emergency vehicle is staffed with 4 FM. Comparably trained regular (RFM) and volunteer (VFM) FM experienced a total of 187 WRIs. The 24-h WRI curve patterns of RFM and VFM were correlated (r?=?0.4, p??.05). Analysis of variance (ANOVA) validated comparable clock-time patterns in WRIs of RFM and VFM each year and each season (all p??.0006; Cosinor analysis, p?相似文献   

Ovulation and follicular growth in gonadotropin-treated gilts followed by in vitro fertilization and development of their oocytes

We investigated whether porcine ovaries derived from FSH-pituitary (FSH-P) or hCG-treated animals can produce oocytes with better in vitro cytoplasmic maturation and in vitro embryonic development relative to those derived from saline-treated animals. The size of the follicle producing the oocyte was also studied. Each of 25 prepubertal gilts received 1 of 6 treatments by intramuscular injection: 1) saline (3 mL, once, n = 5); 2) FSH-P8-3 (8 mg, 3 times, with a 24-h interval, n = 4); 3) FSH-P16-3 (16 mg, 3 times, with a 24-h interval, n = 4); 4) FSH-P16-1-P4-2 (16 mg, once, 4 mg, twice, with a 24-h interval, n = 4); 5) FSH-P16-1 (16 mg, once, n = 4); or 6) hCG (100 IU, 3 times, with a 24-h interval, n = 4). The ovaries were removed by mid-ventral laparotomy 72 h after the first injection. The numbers of corpora hemorrhagica (CH) with each FSH-P treatment were similar (P > 0.05). However, compared with gilts treated with saline or hCG, those treated with FSH-P8-3 had a greater (P < 0.05) number of CH. Treatment with FSH-P8-3 or FSH-P16-3 induced significant growth of medium/large follicles (4 to 8 mm in diameter) compared with saline or FSH-P16-1. The same results were observed when FSH-P8-3 was compared with FSH-P16-P4-2 or hCG. After in vitro fertilization, the rates of male and female pronuclei in oocytes derived from medium/large follicles did not differ (P > 0.05) between treatments, but in oocytes derived from small follicles they were lower (P < 0.05) in saline-treated than in FSH-P16-1-P4-2-treated gilts. After 120 h in culture, the percentages of the inseminated oocytes from 1 to 3 mm or 4 to 8 mm follicles developing to > or = 2-cell did not differ (P > 0.05) between saline- and gonadotropin-treated gilts. However, a higher (P < 0.05) percentage of the inseminated oocytes from 4 to 8 mm follicles had developed to the morula stage or beyond, than those from the 1 to 3 mm follicles. In conclusion, administration of single or multiple doses of FSH-P induced ovulation, but only 8 or 16 mg FSH-P injected 3 times with 24-h intervals for 72 h induced growth of 4 to 8 mm follicles. The size of follicle from which the oocyte derived also had a significant effect on its development in vitro.     

Efficacy of the Ovsynch protocol for synchronization of ovulation and fixed-time artificial insemination in Murrah buffaloes (Bubalus bubalis)

Two experiments were conducted to assess the timing and synchrony of ovulation, plasma LH concentrations, and pregnancy rate in Murrah buffaloes (Bubalus bubalis) treated with the Ovsynch (GnRH-PGF(2 alpha)-GnRH) protocol. In Experiment 1, 10 non-lactating cycling buffaloes received 10 microg of a GnRH analogue i.m. (buserelin acetate) without regard to the stage of the estrous cycle (day of treatment, day 0), followed by 25mg of PGF(2 alpha) i.m. (dinoprost thromethamine) 7 days later. A second-treatment of the same GnRH analogue (10 microg, i.m.) was given 48 h after PGF(2 alpha). Ovulation was confirmed by transrectal palpation (at 2-h intervals) from the second-GnRH treatment to detection of ovulation or up to 96 h after the second-GnRH treatment. Plasma LH concentrations were determined in blood samples collected at 15-min intervals for 6h, starting at the second-GnRH treatment, and thereafter at 2-h intervals until 2h after detection of ovulation. Ovulation occurred in 9/10 buffalo (90%) 23.3+/-1.3h (mean+/-S.E.M.; range 20--32 h) after the second-GnRH treatment. Peak LH concentrations 13.5+/-3.5 ng/mL (range 3.9--40.0 ng/mL) occurred 2.1+/-0.1h (range 1.2-3.0 h) after the second-GnRH treatment. In Experiment 2, 15 lactating, cycling buffaloes were subjected to the Ovsynch protocol, with fixed-time AI 12 and 24h after the second-GnRH treatment and 75 lactating buffaloes were inseminated, approximately 12h after detection of spontaneous estrus. Pregnancy rates were 33.3% for TAI and were 30.7% for buffaloes inseminated following spontaneous estrus (P=0.84). In conclusion, the Ovsynch protocol effectively synchronized ovulation in Murrah buffaloes and resulted in conception rates (to two fixed-time inseminations) that were comparable to those achieved with a single AI after detection of spontaneous estrus.