Diurnal changes in blood metabolites and their relation to plasma growth hormone and time of feeding in mithun heifers (Bos frontalis)

The aim of the present study was to investigate what, if any, diurnal changes occur in blood metabolites in relation to plasma growth hormone (GH) and feeding time among mithun (Bos frontalis), a semi-wild ruminant. Blood samples were collected at hourly intervals during a 24 h span from 6 mithun heifers (averaging 2.5 yr of age and averaging 230 kg in weight) that were fed twice a day at 11:00 and 16:00 h. Samples were assayed for plasma GH and blood metabolites, non-esterified fatty acids (NEFA), glucose, and alpha-amino nitrogen. The total sampling period was divided into a 1) postprandial (after meal) period (period I: 11:00 to 21:00 h) and 2) interprandial period (period II: 22:00 to 10:00 h) and also into night (20:00 to 05:00 h) and day (06:00 to 10:00 h) periods for statistical analysis. Plasma glucose and alpha-amino nitrogen levels increased (p<0.01), and plasma NEFA and GH decreased (p<0.01) after each meal. No diurnal rhythmicity was detected in plasma glucose or alpha-amino nitrogen levels. Interestingly, plasma NEFA and GH levels were higher (p<0.01) during the interprandial (period II) and night periods, indicating an energy deficit that occurred progressively during the interprandial period of nocturnal feed deprivation. In twice-daily-fed mithuns we conclude that: 1) plasma metabolites and GH exhibited a definite pattern of change with time of feeding; 2) concentrations of plasma NEFA were higher nocturnally due to an energy deficit and that GH levels were higher during the interprandial period after the second meal; 3) the interprandial period after the second feeding may be considered to constitute a short-term food deprivation; 4) the longer interprandial period of 19 h in this study between the second and subsequent morning meal may be changed into equally divided feedings to minimize the short-term energy deficit; and 5) blood sampling for blood metabolites in mithuns should be conducted at a fixed time of day with special emphasis on time of feeding.     

Standardization and validation of a simple,sensitive, second antibody format enzyme immunoassay for growth hormone determination in mithun (Bos frontalis) plasma

To facilitate research into the action of growth hormone (GH) in mithun (Bos frontalis), we standardized and validated a simple and highly sensitive enzyme immunoassay (EIA) for GH determination in mithun blood plasma on microtiter plates using biotin‐streptavidin amplification system and the second antibody coating technique. Biotin was coupled to GH and used to bridge between streptavidin‐peroxidase and immobilized antiserum in competitive assay. The EIA was carried out directly in 25 µl mithun plasma. The GH standards ranging from 0.25 ng/well/25 µl to 128 ng/well/25 µl were prepared in charcoal‐treated plasma collected from an aged (>10 years) senile mithun. The sensitivity of EIA procedure was 1.0 ng/ml plasma; the 50% relative binding sensitivity was seen at 36 ng/ml plasma. Plasma volumes for the EIA, namely 12.5 and 25 µl, did not influence the shape of standard curve even though a drop in the optical density (OD)₄₅₀ observed with higher plasma volumes was due to higher inherent GH content in mithun plasma collected from an aged (>10 years) senile mithun. For the biological validation of assay, two mithuns were administered with synthetic bovine GH‐releasing factor (GRF; 10 µg/100 kg body weight; intravenous) and another two were administered sterile normal saline (controls). Jugular blood samples were collected at ?60, ?45, ?30, ?15, ?10, ?5, 0, 5, 10, 15, 30 min and thereafter at 15‐min intervals beginning 1 hour before GRF injection up to 8‐hr post treatment, and samples were assayed for plasma GH. In two animals, a peak of GH was recorded at 15 min of GRF administration, which confirms the biological validation of the EIA. Plasma GH estimated in blood samples collected for 6 consecutive weeks from two different age groups of mithun (Group I, age 0–3 months; Group II, age 3–4 yr) showed higher (P < 0.0001) mean plasma GH in younger than in adult mithuns and consequently higher growth rates in the younger group. A parallelism test conducted between a buffer standard curve of bovine GH and GH measured from serial dilution of mithun plasma containing high concentration of endogenous GH showed good parallelism with a standard curve. In conclusion, the EIA developed for GH determination in mithun blood plasma is sufficiently reliable, economic, and sensitive enough to estimate mithun GH in all physiologic variations. Zoo Biol 0:1–11, 2005. © 2005 Wiley‐Liss, Inc.     

Secretion patterns of growth hormone in growing captive mithuns (Bos frontalis)

A study was conducted in May 2003 to characterize plasma growth hormone (GH) pattern in growing mithuns (Bos frontalis), a rare semi-wild ruminant. Six mithun calves averaging 235 day of age and 124 kg were maintained in semi-intensive system and group-fed once daily. Animals gained at a mean rate of 0.54 kg/day, with individuals ranging from 0.34 to 0.66 kg/day. Blood samples collected at 15-minute intervals starting from 0600h for nine-hour period were assayed for plasma GH. Growth hormone patterns consisted of frequent pulses of varying amplitude. Growth hormone pulses occurred at an average frequency of 0.69/h, the rate did not differ markedly among mithuns nor hour of day. The magnitude of GH secretory pulses varied significantly among mithuns. Growth hormone peaks averaged 95.0 and 45.2 ng/ml in mithuns having the highest and lowest GH peaks, respectively. Peak and mean GH levels were associated positively (r=0.98, P<0.001) and both were associated negatively (r=-0.97 and -0.98, respectively; P<0.01) with rates of gain. Results from the study show that 1) GH peaks occur at frequent intervals throughout the sampling period and 2) alteration in GH levels and patterns are elicited more by pulse amplitude than frequency modulation.     

Postprandial Metabolic Profiles Following Meals and Snacks Eaten during Simulated Night and Day Shift Work

Shift workers are known to have an increased risk of developing cardiovascular disease (CVD) compared with day workers. An important factor contributing to this increased risk could be the increased incidence of postprandial metabolic risk factors for CVD among shift workers, as a consequence of the maladaptation of endogenous circadian rhythms to abrupt changes in shift times. We have previously shown that both simulated and real shift workers showed relatively impaired glucose and lipid tolerance if a single test meal was consumed between 00:00–02:00 h (night shift) compared with 12:00–14:00 h (day shift). The objective of the present study was to extend these observations to compare the cumulative metabolic effect of consecutive snacks/meals, as might normally be consumed throughout a period of night or day shift work. In a randomized crossover study, eight healthy nonobese men (20–33 yrs, BMI 20–25 kg/m²) consumed a combination of two meals and a snack on two occasions following a standardized prestudy meal, simulating night and day shift working (total energy 2500 kcal: 40% fat, 50% carbohydrate, 10% protein). Meals were consumed at 01:00/13:00 h and 07:00/19:00 h, and the snack at 04:00/16:00 h. Blood was taken after an overnight fast, and for 8 h following the first meal on each occasion, for the measurement of glucose, insulin, triacylglycerol (TAG), and nonesterified fatty acids (NEFA). RM-ANOVA (factors time and shift) showed a significant effect of shift for plasma TAG, with higher levels on simulated night compared to day shift (p < 0.05). There was a trend toward an effect of shift for plasma glucose, with higher plasma glucose at night (p = 0.08), and there was a time-shift interaction for plasma insulin levels (p < 0.01). NEFA levels were unaffected by shift. Inspection of the area under the plasma response curve (AUC) following each meal and snack revealed that the differences in lipid tolerance occurred throughout the study, with greatest differences occurring following the mid-shift snack. In contrast, glucose tolerance was relatively impaired following the first night-time meal, with no differences observed following the second meal. Plasma insulin levels were significantly lower following the first meal (p < 0.05), but significantly higher following the second meal (p < 0.01) on the simulated night shift. These findings confirm our previous observations of raised postprandial TAG and glucose at night, and show that sequential meal ingestion has a more pronounced effect on subsequent lipid than carbohydrate tolerance.     

Secretion patterns of luteinizing hormone in growing mithuns (Bos frontalis)

To characterize the luteinizing hormone (LH) secretion patterns in growing mithun (Bos frontalis), a semi-wild ruminant, six female mithuns (1 year old; BW: 145.5 kg) were maintained in a semi-intensive system. Plasma progesterone (P(4)) level was measured in twice-a-week samples collected for six weeks to assess ovarian status. This was followed by a frequent sampling period. Blood samples collected at 15 min intervals for 9 h were assayed for plasma LH. Luteinizing hormone patterns consisted of pulses of varying amplitudes. Luteinizing hormone pulses occurred at an average rate of 0.54/h ( approximately 5 pulses/9 h). The rate did not differ among mithuns. The mean plasma LH levels was correlated with body weight (r=0.82; p<0.05) and pulse amplitude (r=0.87; p<0.01). Neither the LH amplitude nor the frequency was affected by time (p>0.05). The mean plasma P(4) concentration was 0.37 ng/ml. In conclusion, we demonstrated a pulsatile nature of LH secretion in growing mithuns. In addition, the mean plasma LH level and LH amplitude were positively correlated with body weight. It appears that in contrast to cattle, five LH pulses per nine hours recorded in mithuns were not an indication of approaching puberty.     

Development and validation of a highly sensitive economic enzymeimmunoassay for prolactin determination in blood plasma of mithun (bos frontalis) and its application during milk let down and cyclicity

The objective of the present study was to develop and validate highly sensitive and economic enzymeimmunoassay (EIA) for prolactin determination in mithun blood plasma on microtitreplates using the biotin-streptavidin amplification system and second antibody coating technique and to apply this procedure during milk let down and cyclicity in mithuns (Bos frontalis), a semi-wild ruminant. Biotin was coupled to prolactin and used to bridge between streptavidin peroxidase and immobilized antiserum in competitive assay. The EIA was carried out directly in 50 microl mithun plasma. The sensitivity of the EIA procedure was 0.1 ng/ml plasma. Plasma volumes viz., 12.5, 25 and 50 microl did not influence much the shape of standard curve though a slight drop in the OD450 was seen with higher plasma volumes. A parallelism test was carried out to compare the endogenous mithun plasma prolactin with bovine prolactin standards used in the assay. It showed good parallelism with the bovine standard curve. Plasma prolactin was estimated in six cyclic mithun cows during an estrous cycle. Mean plasma prolactin concentrations around the day of estrus were recorded to be higher than any other day of the cycle. Prolactin profiles were also obtained in three mithuns before, during and after milking. A sharp release of prolactin shortly after udder stimulation was observed. High levels of prolactin were maintained during milking, falling sharply thereafter. In conclusion, the EIA developed for prolactin determination in mithun blood plasma is sufficiently reliable, economic and sensitive enough to estimate prolactin in all physiological variation in mithun.     

Behavioral estrous signs can predict the time of ovulation in mithun (Bos frontalis)

The objective of this study was to investigate the relationship of different behavioral estrous signs and time of ovulation to identify if behavioral estrous sign(s) can be used as predictor of time of ovulation in mithuns. Data were collected for 54 ovulations from 16 mithuns. The animals were monitored for onset of estrus by observing different behavioral estrous signs at 2 h interval and bull parading thrice a day for 30 min and were further confirmed by plasma progesterone profile. All animals were also observed for any of the estrous signs at every 2 h interval for 30 min and mounting behavior was studied by bull parading at every 2 h for 30 min after onset of estrus. Time of ovulation was detected by rectal palpation at 2 h interval from onset of estrus till ovulation. Behavioral signs of estrus was more intense in primiparous than multiparous mithuns. Ovulation occurred at 26.1+/-1.1 h (ranging between 20 and 31 h) after the onset of estrus. As the method used to determine the onset of estrus is time consuming, labor intensive and no device is yet available to detect onset of estrus automatically, so this cannot be used practically as a predictor of time of ovulation. The mithun cow at estrus to be mounted by bull was recorded in all cases (100%). Ovulation occurred 23.5+/-1.5 h (ranging between 19 and 27 h) after first mounting. Although promising, mounting cannot be assessed automatically, which limits its practical use as a predictor of ovulation. Standing heat was recorded in 98.1% of total estrus studied in mithun cows and ovulation occurred 21.8+/-1.3 h (ranging between 19 and 25 h) after first observed standing heat. Standing heat can be detected automatically using mounting detectors. Hence, standing heat can be used practically as ovulation predictor in mithuns. In conclusion, cow to be mounted by mithun bull is the best predictor of ovulation, but non-availability of devices to detect it automatically restricts its practical application. Standing heat that recorded 98.1% estrus cases in mithun cows, can also be detected automatically using mounting detector, therefore be used widely as an ovulation predictor in field condition for mithun cows.     

Postprandial metabolic profiles following meals and snacks eaten during simulated night and day shift work

Shift workers are known to have an increased risk of developing cardiovascular disease (CVD) compared with day workers. An important factor contributing to this increased risk could be the increased incidence of postprandial metabolic risk factors for CVD among shift workers, as a consequence of the maladaptation of endogenous circadian rhythms to abrupt changes in shift times. We have previously shown that both simulated and real shift workers showed relatively impaired glucose and lipid tolerance if a single test meal was consumed between 00:00-02:00 h (night shift) compared with 12:00-14:00 h (day shift). The objective of the present study was to extend these observations to compare the cumulative metabolic effect of consecutive snacks/meals, as might normally be consumed throughout a period of night or day shift work. In a randomized crossover study, eight healthy nonobese men (20-33 yrs, BMI 20-25kg/m2) consumed a combination of two meals and a snack on two occasions following a standardized prestudy meal, simulating night and day shift working (total energy 2500 kcal: 40% fat, 50% carbohydrate, 10% protein). Meals were consumed at 01:00/ 13:00 h and 07:00/19:00h, and the snack at 04:00/16:00 h. Blood was taken after an overnight fast, and for 8 h following the first meal on each occasion, for the measurement of glucose, insulin, triacylglycerol (TAG), and nonesterified fatty acids (NEFA). RM-ANOVA (factors time and shift) showed a significant effect of shift for plasma TAG, with higher levels on simulated night compared to day shift (p < 0.05). There was a trend toward an effect of shift for plasma glucose, with higher plasma glucose at night (p = 0.08), and there was a time-shift interaction for plasma insulin levels (p < 0.01). NEFA levels were unaffected by shift. Inspection of the area under the plasma response curve (AUC) following each meal and snack revealed that the differences in lipid tolerance occurred throughout the study, with greatest differences occurring following the mid-shift snack. In contrast, glucose tolerance was relatively impaired following the first night-time meal, with no differences observed following the second meal. Plasma insulin levels were significantly lower following the first meal (p < 0.05), but significantly higher following the second meal (p < 0.01) on the simulated night shift. These findings confirm our previous observations of raised postprandial TAG and glucose at night, and show that sequential meal ingestion has a more pronounced effect on subsequent lipid than carbohydrate tolerance.     

Relationship between plasma growth hormone concentrations and temperament in mithuns (Bos frontalis)

The aim of the present study was to verify whether or not plasma growth hormone (GH) concentrations are correlated with temperament in mithuns (Bos frontalis), a semiwild ruminant. Therefore, a total of 69 female mithuns from four different strains, viz., Arunachal, Nagaland, Mizoram, and Manipur, were divided into six age groups (Group I, 0-6 months; Group II, >6-12 months; Group III, >1-2 years; Group IV, >2-2.5 years; Group V, >2.5-3.0 years; Group VI, >3.0 years). Blood samples were collected weekly for 6 consecutive weeks and assayed for plasma GH. Temperament was scored on a 6-point scale, 6 were being very aggressive and 1 docile. Body weights of all animals were recorded once a week for 6 consecutive weeks GH concentrations and temperament scores were found to differ significantly between groups. Strain had significant effects on blood GH levels and temperament. Blood GH concentrations and temperament of Manipur mithuns were significantly higher than those of the other three strains within each group, for all groups. Across groups III to VI, blood GH levels and temperament among Nagaland, Mizoram, and Arunachal mithuns did not differ. Overall, the strain with the highest blood GH concentrations also had highest temperament scores. The Manipur strain had the highest blood GH levels and exhibited the most aggression (r = 0.95), and Arunachal mithuns, the lowest (r = 0.93). Temperament scores tended to decrease with increasing age for all four strains. Coefficients of correlation between blood GH and temperament among strains within each group, for all groups, were found to be significant. The highly positive correlation (r = 0.94) between blood GH concentrations and temperament for all animals, regardless of age and strain differences, clearly indicates the relationship between blood GH and temperament in mithuns. In conclusion, our results suggest that peripheral blood GH levels can influence temperament in mithuns.     

Effects of high dietary fibre diets formulated from by-products from vegetable and agricultural industries on plasma metabolites in gestating sows

The aim of the present study was to examine the biochemical influence of feeding high dietary fibre (DF) diets formulated from by-products from the vegetable and agricultural industries to sows during early to mid-gestation. The effect of feeding frequency (once vs. twice daily) on diurnal plasma metabolites patterns was also examined. The study included a total of 48 gestating sows from four blocks (12 gestating sows in each block). The sows were fed four different diets containing varying levels of starch (304–519 g/kg dry matter (DM)) and DF (171–404 g/kg DM) but with equal amounts of net energy. The low-DF diet (control) was based on barley and wheat, and the three high-DF diets formulated by replacing barley and wheat by pectin residue, sugar beet pulp and potato pulp, respectively. The experimental design comprised two periods of 4 weeks each. Half the sows were fed once daily at 08:00 h in the first period and twice daily at 08:00 and 15:00 h during the second period, and vice versa for the other half of the sows. Plasma samples from vena jugularis were collected by venipuncture at 07:00, 09:00, 12:00 and 19:00 h. Feeding high-DF increased plasma short-chain fatty acids (p = 0.02) and non-esterified fatty acids (p < 0.001). However, there was no clear effect of DF on glucose and insulin responses. A negative correlation between amount of DF in the diets and plasma creatine (R ² = 1.00; diet effect: p = 0.02) suggested that plasma creatine concentrations was an indicator for the level of glucose–glycogen interchange. Furthermore, an explorative approach using nuclear magnetic resonance spectroscopy-based metabonomics identified betaine (p < 0.001), dimethyl sulfone (DMSO₂; p < 0.001) and scyllo-inositol (p < 0.001) as biomarkers for the different by-products; pectin residue was related to high plasma levels of DMSO₂, sugar beet pulp to plasma betaine, DMSO₂ and scyllo-inositol, and potato pulp to plasma DMSO₂ and scyllo-inositol. In conclusion, replacing starch by DF affected surprisingly few metabolites in peripheral plasma. No negative effects were found in feeding pectin residue, sugar beet pulp or potato pulp for gestating sows as judged from the minor metabolic changes.     

Development of a biotin-streptavidin amplified enzyme immunoassay for oxytocin and its application during milk ejection and the reproductive cycle in the mithun (Bos frontalis)

Oxytocin is a key hormone involved in milk ejection. It plays a key role in regulation of reproductive cyclicity in female mammals by taking part in the process of luteolysis. Determination of oxytocin is, therefore, important for studying the control of its secretion and its role in reproduction of the mithun. A simple and sufficiently sensitive enzyme immunoassay (EIA) for oxytocin determination in mithun plasma using the biotin-streptavidin amplification system and second antibody coating technique was therefore developed. Biotin was coupled to oxytocin and used to bridge between streptavidin-peroxidase and the immobilized oxytocin antiserum in a competitive assay. The EIA was conducted directly in 200 microl of unknown mithun plasma. Standards prepared in hormone-free plasma were used. The lowest detection limit was 0.5 pg/ml plasma. Plasma volumes for the EIA (50, 100, and 200 microl) did not influence the shape of standard curve, even though a drop in OD450 was seen with higher plasma volumes. A parallelism test was carried out to compare endogenous mithun oxytocin with a bovine oxytocin standard. The former showed good parallelism with the bovine standard curve. For biological validation of the assay, plasma oxytocin was measured in the blood samples collected before, during, and after milking in three mithun cows and in six non-lactating cyclic mithuns during the entire estrous cycle. A sharp release of oxytocin shortly after udder stimulation was observed. A high level of oxytocin was maintained during milking, falling sharply thereafter. The mean plasma oxytocin concentration was different on different days of the estrous cycle (P < 0.001). Two peaks of oxytocin were recorded, one at day 6 and another at day 18 of the estrous cycle. In conclusion, a simple, sufficiently sensitive and direct EIA procedure has been developed for the first time to determine plasma oxytocin levels in mithuns. Apart from being non-radioactive, the EIA procedure described here also utilizes a highly stable biotinalyted hormone which has a shelf life of several years, unlike the short shelf life of iodinated tracer used in RIA procedures.     

Effect of mating period and time‐of‐day for bloodmeal on rearing of Asian tiger mosquito (Aedes albopictus) in laboratory conditions

Colonization and maintenance of mosquitoes in the laboratory is required to study physiology, ecology, and behavior of mosquitoes and interactions between mosquito and pathogens. Artificial blood feeding systems have been widely used to maintain the laboratory colony of Aedes albopictus. In this study, we investigated the effects of mating period (1, 3, 6, and 10 days) and time‐of‐day for bloodmeal (08:00, 13:00, and 18:00) in the use of an artificial feeding system on blood‐feeding rate, female fecundity, egg hatching rate, and developmental time of the Asian tiger mosquito, A. albopictus. Younger females mated for three or fewer days reproduced more eggs compared to those of oldest females mated for ten days. Similar to the result for eggs laid, the mean egg‐hatching rate was significantly higher from the offspring of younger females than from those of older females. However, mating period and time‐of‐day for bloodmeal had no effect on the blood feeding rate and developmental time. Taken together, we suggest that three‐day mating with bloodmeal at 18:00 is optimal for maintaining colonies of A. albopictus in laboratory conditions.     

饲料中豆粕替代鱼粉蛋白对异育银鲫生长、代谢及免疫功能的影响

本实验评价了饲料中豆粕替代鱼粉蛋白后对异育银鲫的生长、饲料利用、氮代谢和鱼体免疫力等的影响。实验设计4种等氮等能的饲料,每种3个重复,分别以豆粕替代饲料中鱼粉蛋白的0%（对照,D1）、20%（D2）、80%（D3）和100%（D4）。实验在半循环水养殖系统持续16周,鱼的初重约2.32g,实验期间水温23－30℃。结果表明,随着饲料中豆粕含量的升高,摄食率显著升高(P＜0.05),特定生长率、饲料转化效率、蛋白沉积率和能量沉积率显著降低(P＜0.05);蛋白表观消化率显著升高,干物质和能量表观消化率则显著降低(P＜0.05);总氮摄入量、表观氮摄入量、粪氮排出量、非粪氮排泄量、总氮沉积率均随着饲料中豆粕含量的升高呈显著降低到的趋势(P< 0.05),生产每千克鱼的氮排放量则随着饲料中豆粕含量的升高显著升高(P< 0.05);血清葡萄糖和甘油三酯的含量显著升高,而胆固醇的含量显著降低(P＜0.05);血清的溶菌酶显著降低,超氧化物岐化酶逐渐升高(P＜0.05)。     

Effect of Evening Exposure to Dim or Bright Light on the Digestion of Carbohydrate in the Supper Meal

In a previous study we found that daytime exposure to bright as compared to dim light exerted a beneficial effect on the digestion of the evening meal. This finding prompted us to examine whether the digestion of the evening meal is also affected by evening light intensity. Subjects lived in light of 200 lux during the daytime (08:00–17:00 h) and took their evening meal at 17:00 h under 20 lux (evening dim‐light condition: 17:00–02:00 h) or 2000 lux (evening bright‐light condition: 17:00–02:00 h) until retiring at 02:00 h. Assessment of carbohydrate digestion of the evening meal was accomplished by a breath hydrogen test that is indicative of the malabsorption of dietary carbohydrate. Hydrogen excretion in the breath in the evening under the dim‐light condition was significantly less than under the bright‐light condition (p < 0.05). This finding is the opposite to that obtained in previous experiments in which subjects were exposed to the different intensities of light during the daytime, and indicates that the exposure to dim light in the evening exerts a better effect on carbohydrate digestion in the evening meal than does the exposure to bright light.     

Effects of high dietary fibre diets formulated from by-products from vegetable and agricultural industries on plasma metabolites in gestating sows

The aim of the present study was to examine the biochemical influence of feeding high dietary fibre (DF) diets formulated from by-products from the vegetable and agricultural industries to sows during early to mid-gestation. The effect of feeding frequency (once vs. twice daily) on diurnal plasma metabolites patterns was also examined. The study included a total of 48 gestating sows from four blocks (12 gestating sows in each block). The sows were fed four different diets containing varying levels of starch (304-519 g/kg dry matter (DM)) and DF (171-404 g/kg DM) but with equal amounts of net energy. The low-DF diet (control) was based on barley and wheat, and the three high-DF diets formulated by replacing barley and wheat by pectin residue, sugar beet pulp and potato pulp, respectively. The experimental design comprised two periods of 4 weeks each. Half the sows were fed once daily at 08:00 h in the first period and twice daily at 08:00 and 15:00 h during the second period, and vice versa for the other half of the sows. Plasma samples from vena jugularis were collected by venipuncture at 07:00, 09:00, 12:00 and 19:00 h. Feeding high-DF increased plasma short-chain fatty acids (p = 0.02) and non-esterified fatty acids (p < 0.001). However, there was no clear effect of DF on glucose and insulin responses. A negative correlation between amount of DF in the diets and plasma creatine (R2 = 1.00; diet effect: p = 0.02) suggested that plasma creatine concentrations was an indicator for the level of glucose-glycogen interchange. Furthermore, an explorative approach using nuclear magnetic resonance spectroscopy-based metabonomics identified betaine (p < 0.001), dimethyl sulfone (DMSO2; p < 0.001) and scyllo-inositol (p < 0.001) as biomarkers for the different by-products; pectin residue was related to high plasma levels of DMSO2, sugar beet pulp to plasma betaine, DMSO2 and scyllo-inositol, and potato pulp to plasma DMSO2 and scyllo-inositol. In conclusion, replacing starch by DF affected surprisingly few metabolites in peripheral plasma. No negative effects were found in feeding pectin residue, sugar beet pulp or potato pulp for gestating sows as judged from the minor metabolic changes.     

Meal pattern of male rats maintained on histidine-, leucine-, or tyrosine-supplemented diet

Objective: Food intake is known to be affected by macronutrient composition of the diet, and protein manipulation has been reported to alter food intake, but the effect of individual amino acids on eating behavior has not been fully studied. This study investigated the effect of diet supplementation with three individual amino acids on meal pattern in male rats. Research Methods and Procedures: Thirty‐two Sprague‐Dawley rats were randomly divided into four equal groups and fed control diet or histidine (5%)‐, leucine (5%)‐, or tyrosine (5%)‐supplemented diet for 2 weeks and were monitored for their meal pattern. Results: Total food intake and feeding rate of the different groups were not affected, although other components of meal pattern were altered. Histidine supplementation reduced diurnal meal size by 42% (p < 0.05), whereas that of leucine increased nocturnal meal size by ～35% (p < 0.05). Tyrosine supplementation increased food intake of the nocturnal period and decreased that of the diurnal period. Both histidine and tyrosine supplementation elevated fasting plasma insulin levels and suppressed fasting glucose significantly. Discussion: Individual amino acids were found to alter meal pattern differently. Further investigations are required to dissect the involvement of central and peripheral factors in these alterations.     

Plasma Enterostatin: Identification and Release in Rats in Response to a Meal

Objective: To discover a possible absorption and/or secretion of enterostatin into the circulating blood, as well as to compare the levels of circulating enterostatin after high‐fat feeding and low‐fat feeding. Research Methods and Procedures: Using a specific enzyme‐linked immunosorbent assay, plasma enterostatin levels were determined after feeding a high‐fat, a high‐fat/‐sucrose, or a low‐fat meal to Sprague‐Dawley rats deprived of food overnight. Results: The enterostatin levels were increased by all diets; the response to the high‐fat and the high‐fat/‐sucrose meals was greater in magnitude and duration than that to the low‐fat meal. In addition, enterostatin levels correlated with the intake of dietary fat. Plasma enterostatin levels after high‐fat feeding were found to be similar to those after intravenous administration of exogenous enterostatin known to inhibit high‐fat food intake. Gel chromatography of pooled postprandial plasma extracts followed by high‐performance liquid chromatography analysis showed that plasma enterostatin was identical to synthetic enterostatin. Affinity cross‐linking of plasma proteins with ¹²⁵I‐enterostatin on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, followed by autoradiography, revealed a single band with a molecular weight of about 66 kDa, indicating the presence of a potential enterostatin‐binding protein in plasma. Discussion: The measurements of plasma enterostatin may be a sensitive indicator for the measurement of fat intake.     

Ovarian and hormonal responses to a progesterone-releasing controlled internal drug releasing treatment in dietary-restricted goats

An experiment was conducted to evaluate the effects of dietary restriction on ovarian, endocrine (ovarian steroids and luteinizing hormone (LH) pulse) and metabolic (glucose, insulin and non-esterified fatty acid (NEFA)) profiles in goats treated with a progesterone-releasing controlled internal drug releasing (CIDR-G) device. Cycling goats were offered either a maintenance or a restricted (30% of requirement; n =4 per treatment) level of feeding. The dietary restriction was started on the day following ovulation. At 30-32 days after the start of food restriction, the goats received a prostaglandin F(2alpha) (2mg of dinoprost) injection followed by 10 days of CIDR-G treatment. Ovarian ultrasonographic images were monitored daily throughout the experiment and blood samples were collected daily just before the morning feeding for analysis of endocrine and metabolic profiles. Frequent blood samples (1 ml) were also collected at 10 min intervals for 8 h from -8 h to CIDR-G removal, and from 32 to 40 h after CIDR-G removal for analysis of LH pulses. Body weight was significantly (P < 0.05) decreased in the food-restricted animals. Oestrous behaviour and ovulation followed by a rise of plasma progesterone concentration were observed after the CIDR-G removal in all control animals but not in any of the food-restricted animals within 12 days after CIDR-G removal. The LH pulse frequency from 32 to 40 h after the CIDR-G removal was significantly (P < 0.05) lower in the food-restricted animals than in control animals (1.5 +/- 0.6 versus 3.8 +/- 0.5 pulses for 8 h). There was no significant difference in the glucose concentration in weekly plasma samples between control and food-restricted animals. Insulin concentrations from 2 weeks after the start of feed restriction were significantly (P < 0.05) lower in restricted animals than in control animals. The NEFA concentration in restricted animals was significantly (P < 0.05) increased after the start of feed restriction, and then decreased gradually to the basal level. The present results suggest that nutritionally induced anovulation after CIDR-G treatment is associated with a reduction in the frequency of LH pulses, and that insulin and NEFA, rather than the glucose concentration in the circulation, may be associated with the metabolic suppression of LH pulses.     

The effect of altering the 20:5n-3 and 22:6n-3 content of a meal on the postprandial incorporation of n-3 polyunsaturated fatty acids into plasma triacylglycerol and non-esterified fatty acids in humans

Previous studies suggest that consuming meals containing large amounts of fish oil is associated with selective postprandial incorporation of 20:5n-3 and 22:6n-3 into plasma non-esterified fatty acids (NEFA). We investigated the effect of consuming meals containing different amounts of 20:5n-3 and 22:6n-3 comparable to dietary habits of western populations on the postprandial incorporation of 18:3n-3, 20:5n-3 and 22:6n-3 into plasma triacylglycerol (TAG) and NEFA over 6h in middle aged subjects. 20:5n-3 incorporation into plasma TAG was greater than 22:6n-3 irrespective of the test meal. Conversely, 22:6n-3 incorporation into plasma NEFA was greater than 20:5n-3, irrespective of the test meal. There was no effect of the amount of 20:5n-3+22:6n-3 in the test meal on the 18:3n-3 incorporation into plasma TAG or NEFA. These findings suggest differential metabolism of 20:5n-3 and 22:6n-3 in the postprandial period when consumed in amounts typical of western dietary habits.     

Diurnal rhythms of plasma growth hormone,somatostatin, thyroid hormones,cortisol and glucose concentrations in rainbow trout,Oncorhynchus mykiss,during progressive food deprivation

Abstract

The diurnal patterns of changes in plasma cortisol, growth hormone (GH), somatostatin‐14 (SRIF), thyroid hormones (L‐thyroxine, T₄ and triiodo‐L‐thyronine, T₃) and glucose were investigated in rainbow trout, Oncorhynchus mykiss, both during single meal‐feeding and during a progressive fast of 13 weeks. All measured variables exhibited a diurnal pattern in fed rainbow trout, most of which appeared to be correlated with the time of feeding (30–60 min after the onset of light), while additional changes, associated with the scotophase were also found for cortisol. Although fasting had no affect on mean daily plasma cortisol or SRIF concentrations, there was a progressive increase in mean daily plasma GH concentrations and a progressive decrease in mean daily plasma thyroid hormone and glucose concentrations associated with fasting. However, for GH, significant changes were not evident until week 10 of the fast. In addition, fasting appeared to phase‐shift the diurnal patterns of plasma GH, cortisol and glucose concentrations; the consequence of such a shift is that conclusions as to the effects of fasting, if based on a single time of sampling, may be flawed.