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1.
Plasma IGF-I, IGF binding protein-2 (IGFBP-2), and IGFBP-3 were quantified in growing Angus bulls (n = 56) to determine their relationship with postweaning growth and carcass ultrasound measurements. In addition, GH response to GHRH challenge (area-under-the-curve GH [AUC-GH) was determined for each bull as part of a previous study. Blood was collected by jugular venipuncture at the start of a 140-d postweaning growth performance test and at 28 d intervals for plasma IGF-I determination by RIA. Plasma IGFBP-2 and -3 content was measured at the start of the study, on d 70, and d 140 by Western ligand blotting. Individual weights and hip heights were measured every 28 d during the study and carcass longissimus muscle area, intramuscular fat percentage, and carcass backfat were estimated by ultrasound on d 140. Greater plasma IGF-I at the start of the performance test was associated with reduced postweaning ADG and increased longissimus area. Throughout the performance test period, the correlations between plasma IGF-I and hip height were consistently positive, ranging from 0.10 to 0.38, but the correlations between ADG and IGF-I varied from -0.32 to 0.31. Age-adjusted d-1 plasma IGFBP-2 was related to ADG during the performance test, explaining nearly 30% of the variation in ADG. A model combining weaning age, IGFBP-2, and AUC-GH showed a strong relationship with ADG (R2 = 0.40). Plasma IGFBP-2 and -3 were not related to carcass characteristics, and IGFBP-3 was not related to growth rates. This study provides additional evidence for the variable relationship between plasma IGF-I and growth rates in cattle. A significant positive relationship between plasma IGFBP-2, AUC-GH, and postweaning ADG warrants further investigation.  相似文献   

2.
Effects of daily injections of pituitary-derived bovine somatotropin (bST) for 6 wk were evaluated in 10 growing heifers and compared to 9 placebo-treated control animals. Bovine somatotropin was injected at 50 micrograms/kg BW each day. Body weight and growth, plasma concentrations of insulin-like growth factor I (IGF-I) and somatotropin (ST) were assessed. To measure plasma concentrations of IGF-I, we validated a RIA in which bovine plasma samples were extracted with acid-ethanol, a method that resulted in greater than 90% recovery of IGF-I. Average daily gain was similar during the first 4 wk of the experiment in both control and bST-treated groups; however, at the end of the experimental period (wk 4 and 6) ADG was greater (P less than .05) in bST-treated heifers (1.24 +/- .21 kg/d vs .75 +/- .25 kg/d). Plasma IGF-I from wk 2 to wk 6 were increased in bST-treated animals (452 +/- 97 ng/ml at wk 2; 683 +/- 106 ng/ml at wk 6) compared with controls (293 +/- 62 ng/ml at wk 2 (P less than .01) and 293 +/- 115 ng/ml at wk 6 (P less than .001). Moreover, ADG over the 6-wk experimental period was correlated with mean IGF-I concentrations determined over the same period (r = .55; P less than .01). As expected, mean plasma ST concentrations were increased in bST-injected animals from wk 1 to 6. Gel chromatographic profiles of bovine plasma exhibit a 150,000 molecular weight ST-dependent binding protein-IGF-I complex and a 30,000 molecular weight non-ST-dependent complex. This study validates a method for measuring IGF-I in cattle, and shows a positive relationship among IGF-I and ADG after ST treatment. No correlation, however, was found between plasma ST and growth performance.  相似文献   

3.
Previous studies have shown that supplementation of sow diets with L-carnitine increases the body weight of piglets at birth. This study was conducted to elucidate the reasons for this phenomenon. Three experiments with 24 (experiment 1), 40 (experiment 2) and 12 (experiment 3) sows were conducted. In all three experiments, sows were allotted to two groups which had free access to a nutritionally adequate diet. Sows of one group were supplemented with 125 mg L-carnitine/day during pregnancy; sows of the other group (control group) did not receive L-carnitine. In experiment 1, plasma samples were collected at day 95 of pregnancy, in experiment 2 plasma samples were collected at days 80 and 100 of pregnancy. In experiment 3, chorions of the sows were collected at parturition. L-carnitine-treated sows had higher plasma concentrations of total L-carnitine than control sows (p < 0.05). The number of piglets born and weights of litter and individual piglets at birth were not different between both groups in all three experiments. L-carnitine-treated sows had higher plasma concentrations of insulin-like growth factor-I (IGF-I) on day 80 of pregnancy (experiment 2, p < 0.05) and on day 95 (experiment 1, p < 0.10), and a higher plasma concentration of IGF-II on day 80 (experiment 2, p < 0.05) than control sows. Moreover, sows supplemented with L-carnitine had heavier chorions (+22%, p =0.10) with greater amounts of protein (+45%, p < 0.05) and DNA (+38%, p < 0.10) and a higher protein concentration of glucose transporter-1 (+62%, p < 0.05). Plasma concentrations of 17beta-oestradiol, progesterone and thyroid hormones as well as concentrations of urea and total free amino acids were not different between both groups of sows. Plasma concentrations of non-esterified fatty acids, ketone bodies, triacylglycerols and cholesterol were also largely indifferent between both groups of sows. In conclusion, this study shows that L-carnitine has less influence on lipid metabolism and utilization of nitrogen in pregnant sows but increases their plasma concentrations of IGFs. This in turn may enhance development of the placentae and the intrauterine nutrition of the fetuses. This may be the reason for increased birth weights observed in recent studies in sows supplemented with L-carnitine.  相似文献   

4.
Insulin resistance has been suggested to increase the risk of certain diseases, including osteochondrosis and laminitis. Our objective was to evaluate the effect of adaptation to high-glycemic meals on glucose-insulin regulation in healthy Thoroughbred weanlings. Twelve Thoroughbred foals were raised on pasture and supplemented twice daily with a feed high in either sugar and starch (SS; 49% nonstructural carbohydrates, 21% NDF, 3% crude fat on a DM basis) or fat and fiber (FF; 12% nonstructural carbohydrates, 44% NDF, 10% crude fat on a DM basis). As weanlings (age 199 +/- 5 d; BW 274 +/- 5 kg) the subjects underwent a modified frequently sampled i.v. glucose tolerance test. A series of 39 blood samples was collected from -60 to 360 min, with a glucose bolus of 300 mg/kg BW injected at 0 min and an insulin bolus of 1.5 mIU/kg BW at 20 min. All samples were analyzed for glucose and insulin, and basal samples also were analyzed for plasma cortisol, triglyceride, and IGF-I. The minimal model of glucose and insulin dynamics was used to determine insulin sensitivity (SI), glucose effectiveness, acute insulin response to glucose (AIRg), and disposition index (DI). Insulin sensitivity was 37% less (P = 0.007) in weanlings fed SS than in those fed FF; however, DI did not differ (P = 0.65) between diets because AIRg tended to be negatively correlated with SI (r = -0.55; P = 0.067). This finding indicates that the SI decrease was compensated by AIRg in the weanlings adapted to SS. This compensation was further demonstrated by greater insulin concentrations in SS-adapted weanlings compared with FF-adapted weanlings at 11 of 36 sample points (P < 0.055) and greater (P = 0.040) total area under the insulin curve in SS than in FF weanlings. Plasma cortisol and triglycerides did not differ between dietary groups, but IGF-I was greater (P = 0.001) in SS weanlings. Despite appearing healthy, horses adapted to high-glycemic feeds may exhibit changes in altered insulin sensitivity and compensation that increase the risk of diseases involving insulin resistance. These changes seem to be partially amenable to dietary management.  相似文献   

5.
Previous research has demonstrated that increasing the CP concentration from 16 to 26% in milk replacers fed to male preruminant dairy calves at 1.5% of BW (DM basis) daily resulted in increased ADG, G:F, and deposition of lean tissue. However, the effects of dietary CP would be expected to vary depending on ME intake. Here, male Holstein calves < 1 wk old were used to determine the effects of feeding rate and CP concentration of isocaloric, whey protein-based milk replacers on growth and body composition. After a 2-wk standardization period, calves were assigned randomly to an initial baseline group or to treatments in a 2 x 4 factorial arrangement of feeding rate (1.25 or 1.75% of BW daily, DM basis) and milk replacer CP concentration (14, 18, 22, or 26% of DM). No starter was offered, but calves had free access to water. After a 5-wk feeding period, calves were slaughtered and body composition was determined. Increasing the feeding rate increased (P < 0.05) ADG, G:F, empty-body gains of chemical components and energy, the percentage of fat in empty BW gain and in the final empty body, and concentrations of IGF-I and insulin in plasma. Increasing the feeding rate decreased (P < 0.01) percentages of water and protein in the empty body and decreased urea N in plasma. Increasing dietary CP concentration linearly increased (P < 0.05) ADG, body length, heart girth, and gains of water and protein but linearly decreased (P < 0.05) fat gain. As dietary CP increased, fat content in empty body gain decreased, and water and protein increased. Increasing CP concentration increased (quadratic, P < 0.02) G:F, with greatest efficiencies for calves fed 22% CP. Gross energetic efficiency (retained energy:intake energy) was greater (P < 0.05) for calves fed at 1.75% of BW daily. Efficiency of dietary protein use for protein gain was greater for calves fed at 1.75% of BW daily but was not affected by dietary CP. The ratio of protein gain to apparently digestible protein intake above maintenance decreased as dietary CP increased. Interactions (P < 0.05) of feeding rate and CP concentration for gains of water and protein indicated that when dietary CP was 26% the ME supply limited protein use by calves fed at 1.25% of BW daily. Body composition of preruminant calves can be markedly altered by manipulating the protein to energy ratio in milk replacers. These dietary effects on body composition and growth are not predicted by current NRC standards.  相似文献   

6.
An isotope dilution method using [U-(13)C]glucose injection was applied to determine the effects of dietary energy intake and cold exposure on plasma glucose metabolism in sheep. The sheep were assigned to two dietary treatments and were fed on diets containing either 100% or 160% of ME and both containing 150% of dietary crude protein intake for maintenance. The sheep were exposed from a thermoneutral environment (23 degrees C) to a cold environment (2-4 degrees C) for 5 days. The isotope dilution method was performed on the 18th day in the thermoneutral environment and on the fifth day of cold exposure. Plasma concentrations of glucose and NEFA increased (p < 0.05) during cold exposure for both diets. Plasma glucose pool size remained unchanged (p = 0.67), but plasma glucose turnover rate tended to increase (p = 0.07) with increased energy intake. Both pool size and turnover rate of plasma glucose increased (p = 0.01 and p = 0.0001, respectively) during cold exposure. No significant diet x environment interaction was detected. It is concluded that plasma glucose metabolism was influenced by both dietary energy intake and cold exposure, and plasma glucose metabolism in response to cold exposure was not modified by energy intake in sheep under the conditions (2-4 degrees C on the fifth day) of the present experiment.  相似文献   

7.
The influences of thermal environment and individual growth rate on somatotroph and lactotroph function were examined in 6-week-old barrows reared entirely in a hot (H: 27–32°C, n = 8) or cool (C: 21°C, n = 10) environment. Growth hormone (GH) and prolactin (PRL) cell contents and responses to growth hormone-releasing hormone (GHRH) or thyrotropin-releasing hormone (TRH) were evaluated in cultured pituitary cells from each animal. Plasma GH, PRL, and insulin-like growth factor-1 (IGF-1) concentrations also were monitored. Thermal environment did not affect in vitro GH secretion, cellular GH content, or plasma GH concentrations. Stimulated in vitro GH release (GHRH-basal) and plasma GH were inversely related to average daily gain (ADG, r = −.76, p < .005 and r = −.51, p < .05, respectively). Cellular GH content also declined as ADG increased (r = −.57, p < .05). Plasma IGF-1 concentrations were not affected by thermal environment and were not related to ADG. Pituitary cells from H animals secreted and contained more PRL than cells from C animals (p < .05). Plasma PRL values were correlated with ADG (r = .54, p < .05), but did not differ between thermal groups. Stimulated in vitro PRL (TRH-vehicle) secretion was positively related with ADG only in the H group (r = .97, p < .001). In contrast, cellular PRL content decreased with ADG in cells from the H barrows (r = −.8, p < .05). Lactotroph function was not related to growth in cells from C pigs. In summary, 1) heat enhanced PRL secretion and cell content; 2) growth and somatotroph function were inversely related; and 3) serum PRL and the PRL response to TRH in cells from H barrows were positively related to growth.  相似文献   

8.
A study was undertaken to investigate the changes of plasma non-esterified fatty acids (NEFA), glucose and alpha-amino nitrogen and their relationship with age, body weight (BW) and plasma growth hormone (GH) in growing buffaloes. For the purpose, six growing female Murrah buffalo calves of 6-8 months of age were selected on the basis of their BW and fed according to Kearl standard (Nutrient Requirements of Ruminants in Developing Countries, International Feedstuffs Institute, Utah State University, Utah, USA, 1982, p. 89) for growing buffaloes (target growth rate 500 g/day) to meet energy and protein requirement of the animals. Blood samples collected at fortnight intervals for 1 year were analysed for plasma NEFA, glucose, alpha-amino nitrogen and GH. The animals were also weighed at fortnight intervals. Plasma NEFA and glucose levels were found to decrease (p < 0.01) with age. Unlike plasma NEFA and glucose, plasma alpha-amino nitrogen level increased (p < 0.01) as the buffaloes become older. Plasma NEFA and glucose concentrations in growing buffaloes were found to be positively correlated with plasma GH (r = 0.379 and 0.420 respectively), but these were non-significant (p > 0.01). However, plasma NEFA and glucose showed a good correlation (p < 0.01; r = 0.780 and 0.652 respectively) with plasma GH per 100 kg live weight. Plasma alpha-amino nitrogen exhibited non-significant (p > 0.01) negative correlation (r = -0.295) with plasma GH but a negative correlation (p < 0.01; r = -0.641) with GH per 100 kg BW. So, plasma metabolites showed a definite pattern of change during growth and these have a significant (p < 0.01) correlation with plasma GH per 100 kg BW than GH.  相似文献   

9.
This study was conducted to determine the effect of supplementation with Lys, Met, Thr to low-protein diets on growth performance and metabolic responses in growing barrows. Seventy crossbred barrows (Duroc × Yorkshine), with an average initial body weight of 16 kg, were fed diets containing five crude protein (CP) levels (18.2, 16.5, 15.5, 14.5, and 13.6%) and 0.83% true ileal digestible lysine. On d 17 of the trial, all pigs were fitted with an indwelling jugular catheter for blood collection. On d 18 and 53, blood samples were obtained at 4 h post feeding. Reducing dietary CP concentration linearly decreased (P < 0.05) ADG, ADFI, feed efficiency, longissimus muscle area (LMA), and plasma concentrations of urea N and protein, while increasing backfat thickness linearly (P < 0.05). Pigs fed the 13.6% CP diet exhibited the poorest growth performance. On d 53, dietary CP affected plasma IGF-I (quadratic, P < 0.01) and leptin (linear, P < 0.01) concentrations. Plasma leptin levels were correlated positively with backfat thickness (r = 0.76, P < 0.05) and negatively with LMA (r = − 0.64, P < 0.01). There was a positive correlation between ADG and plasma IGF-I concentrations (r = 0.91, P < 0.05). Our results suggest that adequate provision of nonessential AA and all EAA is required for achieving maximum growth performance and reducing fat accretion in growing pigs fed low-CP diets.  相似文献   

10.
Spray-dried animal plasma sourced from bovine, porcine or other animal origin is often used as a main feed ingredient in the diets of weanling piglets to improve growth performance. The objective of this study was to determine the effect of animal plasma in diets on the performance of piglets in the post-weaning period, with and/or without pathogenic challenge, by undertaking a meta-analysis. Data were extracted from peer-reviewed reports published in scientific journals. The average initial weight of the piglets was 5.8 kg and the average initial age 19 days (2–56 days). The average duration of feeding animal plasma was 40 days. Average daily gain (ADG), feed intake (ADFI) and feed conversion ratio (FCR) were found to be 22–28 g/day, 20–27 g/day and −0.28 to 0.06 g/g. Generally, diet supplemented with spray-dried bovine plasma (SDBP) improved the ADG of the piglets and spray-dried porcine plasma (SDPP) led to increases in the ADFI. For the first week post-weaning alone, as the dietary animal plasma percentage increased there was an increase in ADG and ADFI; similarly, the latter two measures increased as weaning age increased. The evidence suggests that mainly IgG present in animal plasma prevents the binding of pathogens to the gut wall and reduces the incidence of sub-clinical infection in the post-weaning stage. Animal plasma containing IgG appears to be a useful in-feed supplement for piglets in the post-weaning phase.  相似文献   

11.
Twenty barrows were used to determine if partial replacement of protein-bound AA with crystalline AA (CAA) reduces AA use for muscle tissue and whole-body growth. Barrows (44.2 +/- 1.3 kg of BW) were assigned to 4 diets in a randomized complete block design. Diets consisted of 16.1% CP with no CAA, and 12.8, 10.1, and 7.8% CP containing CAA. As the CP concentration decreased, CAA were gradually increased to meet requirements on a true ileal digestibility basis. Barrows were weighed on d 0 and 13. Blood samples were collected before the morning feeding on d 0, 6, and 12 (prefeeding), and 2 h after the morning feeding on d 13 (postfeeding). Pigs were euthanized on d 13, and liver and right LM were removed and weighed. The reduction in the dietary CP concentration linearly decreased (P < 0.01) ADG, G:F, LM weight, and the CP content of LM. Reducing the CP concentration decreased pre- and postfeeding plasma concentrations of IGF-I (linear, P < 0.01) and insulin (linear, P < 0.10). The reduction in the dietary CP concentration increased prefeeding plasma concentrations of Ala, Gln, Gly, and total AA but decreased Arg, Asn, His, Ile, Phe, Trp, and Tyr (linear, P < 0.05). Plasma concentration of total indispensable AA decreased initially and increased thereafter as the dietary CP concentration decreased from 16.1 to 7.8% (quadratic, P < 0.01). The reduction in the dietary CP concentration increased postfeeding plasma concentrations of Ala, Lys, Met (linear, P < 0.01), and Gly (linear, P = 0.073) and decreased Asn, Ser, Tyr, Arg, His, and Leu (linear, P < 0.05). Plasma concentrations of Ile, Phe, Thr, Trp, and Val decreased initially and increased thereafter as the dietary CP concentration decreased from 16.1 to 7.8% (quadratic, P < 0.05). In muscle tissue, concentrations of free Ala, Asp, Glu, Gln, Gly, and Lys increased (linear, P < 0.05) as the dietary CP concentration decreased. Concentrations of free His, Ile, Phe, Thr, Trp, and Val in muscle tissue decreased initially and increased thereafter as the dietary CP concentration decreased from 16.1 to 7.8% (quadratic, P < 0.05). In summary, the reduction in the dietary protein-bound AA decreased whole-body and LM growth, altered the free AA pool profile in muscle tissue, and decreased plasma insulin and IGF-I. As the replacement of protein-bound AA with CAA increased, 1) free Ala and Gln in muscle tissue increased, indicating an increase of muscle tissue protein breakdown; and 2) utilization of indispensable AA in muscle tissue decreased.  相似文献   

12.
Previous studies have reported conflicting data on gender differences in plasma IGF-I in postnatal pigs. There is also debate over the role of IGF-II in regulation of postnatal growth. We have, therefore, determined the concentrations of plasma IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) in boars, barrows, and gilts and related these to postnatal growth characteristics. Plasma concentrations of IGF-I were higher in boars than in gilts or barrows from 13 wk. of age, and plasma IGF-II levels were generally higher in barrows than in boars or gilts. Plasma IGFBP-3 levels were higher in boars than in gilts or barrows at most ages. Between 15 and 23 wk. of age, IGF-I and IGFBP-3, but not IGF-II, were positively associated with growth rate, voluntary feed intake, and gain:feed ratio. Plasma IGF-II, but not IGF-I or IGFBP-3, was positively associated with backfat depth during this period. These results support the hypothesis that circulating IGF-I and IGF-II are regulators of lean and adipose tissue growth, respectively.  相似文献   

13.
Two experiments were conducted to determine the effects of dietary sodium butyrate on growth performance and response to Escherichia coli lipopolysaccharide (LPS) in weanling pigs. In a 28-d experiment, 180 pigs (initial BW 6.3 kg) were fed 0, 0.05, 0.1, 0.2, or 0.4% sodium butyrate, or 110 mg/kg of dietary tylosin. There was no effect of dietary sodium butyrate or tylosin on overall G:F, but there was a linear trend (P < 0.07) toward decreased ADFI and ADG as levels of sodium butyrate increased. In a second 28-d experiment, 108 pigs (initial BW 6.3 kg) were assigned to 1 of 3 dietary treatments: 1) no antibiotics, 2) 0.2% sodium butyrate, or 3) 55 mg/kg of carbadox. On d 14, a subset of pigs from the no-antibiotic and butyrate treatment groups was challenged with E. coli LPS or injected with sterile saline in a 2 x 2 factorial arrangement (+/-LPS challenge; +/-dietary butyrate; n = 6 pigs/treatment group). Four hours after LPS challenge, blood samples were obtained, and samples of LM, liver, and ileum were collected for gene expression analysis. Serum samples were analyzed for IL-6, tumor necrosis factor alpha (TNFalpha), alpha(1)-acid glycoprotein, cortisol, IGF-I, insulin, and metabolites. The relative abundance of tissue cytokine and IGF-I mRNA was measured by real-time PCR. Feeding diets containing sodium butyrate or carbadox did not alter ADG or ADFI compared with pigs fed the control diet. From d 0 to 14, pigs fed diets containing 0.2% sodium butyrate had decreased (P < 0.05) ADG and tended (P < 0.06) to have decreased G:F compared with animals fed diets containing carbadox. Challenge with LPS increased (P < 0.05) serum cytokines and cortisol and decreased (P < 0.05) serum glucose and triglycerides. Injection with LPS increased (P < 0.05) the relative abundance of hepatic IL-6 and TNFalpha mRNA, increased (P < 0.05) LM TNFalpha mRNA content, and decreased (P < 0.05) IGF-I mRNA in LM. For serum cortisol, there was an interaction (P < 0.05) between dietary butyrate and LPS. The increase in serum cortisol attributable to LPS was greater (P < 0.05) in pigs fed butyrate than in pigs fed the control diet. There tended (P < 0.10) to be an interaction between LPS and diet and for butyrate to increase the relative abundance of IL-6 mRNA in LM. Carbadox did not alter cytokine or IGF-I mRNA or serum metabolites, but did decrease (P < 0.05) serum TNFalpha. These data indicate that dietary sodium butyrate does not enhance growth performance, but may regulate the response to inflammatory stimuli in weanling pigs.  相似文献   

14.
Effects of different carbohydrate sources on plasma glucose, insulin and insulin-like growth factor-I (IGF-I) levels were compared to subsequently be able to study effects of insulin-stimulating diets on follicle development in sows. The following feed components were tested in 12 sows during six consecutive test periods of 9.5 days: dextrose (DEX), sucrose (SUC), lactose (LAC), dextrose plus lactose (DL), sucrose plus lactose (SL), dextrose plus sugarbeet pulp (DSBP) and control (CON). On day 2, 5 and 9 of each test period, plasma glucose (only at day 9), insulin and IGF-I profiles were determined. Despite similar glucose profiles for all diets, the postprandial insulin response was higher for DL and SL compared with CON and LAC; the other diets were intermediate. Plasma IGF-I levels were higher in CON, LAC and SL compared with DSBP, but differences were only marginal. It was concluded that dextrose and sucrose have the potential to stimulate fast and high insulin peaks, especially when combined with additional lactose. Despite the high dextrose in the DSBP diet, the insulin response was flattened, probably due to the viscosity of sugarbeet pulp. The results show that modulation of plasma insulin levels by dietary carbohydrates seems possible in anabolic sows, but IGF-I levels are less easily modified.  相似文献   

15.
This study aimed to evaluate the correlation of seminal plasma IGF-I and total proteins from peripubertal bulls with semen characteristics and onset of puberty. Sixteen dairy Gyr bulls were separated into early (n = 8) and regular (n = 8) groups, according to the onset of puberty. Semen was monthly collected by electroejaculation from 14 to 26 months of age, and the onset of puberty was retrospectively determined (17.0 ± 1.6 and 19.2 ± 1.5 months, to early and regular group, respectively). Five time points were evaluated (day −60, day −30, day 0, day 30 and day 60 days of puberty), being day 0 considered as beginning of puberty. Scrotal circumference and body weight were also assessed. Semen characteristics were evaluated, the seminal plasma was separated by centrifugation and total protein and IGF-I concentrations were determined. There was no difference between groups to concentration of the seminal plasma total proteins, but we found an interaction between group and age. Seminal plasma IGF-I concentrations were not different between early and regular groups; thus, the data were combined for analysis. Combined IGF-I concentrations were positively correlated with sperm motility and concentration, age, body weight and scrotal circumference. Negative correlation was found between IGF-I concentration and total sperm defects. Increased IGF-I was observed in day −30 and day 0 of puberty in early and regular groups, respectively. Seminal plasma total proteins are involved in peripubertal modifications and IGF-I from Zebus dairy bulls can influence the seminal characteristics and the growth factor increase occurs concomitantly with body growth but cannot be used to define puberty bulls earlier.  相似文献   

16.
In this study the hypothesis that irreversible glucose loss results in an 'uncoupling' of the somatotrophic axis (increasing plasma GH levels and decreasing plasma IGF-I) was tested. During periods of negative energy balance the somatotrophic axis respond by increasing plasma GH and decreasing plasma IGF-I levels. In turn, elevated GH repartitions nutrient by increasing lipolysis and protein synthesis, and decreases protein degradation. Irreversible glucose loss was induced using sub-cutaneous injections of phloridizin. Seven non-lactating cows were treated with 8g/day phloridizin (PHZ) and seven control animals (CTRL, 0g/day), while being restricted to a diet of 80% maintenance. PHZ treatment increased urinary glucose excretion (P<0.001), resulting in hypoglycemia (P<0.001). As a response to this glucose loss, the PHZ treated animals had elevated plasma NEFA (P<0.005) and BHBA (P<0.001) levels. Average plasma insulin concentrations were not altered with PHZ treatment (P=0.059). Plasma GH was not different between the two groups (P>0.1), whereas plasma IGF-I levels decreased significantly (P<0.001) with PHZ treatment. The decline in plasma IGF-I concentrations was mirrored by a decrease in the abundance of hepatic IGF-I mRNA (P=0.005), in addition the abundance of hepatic mRNA for both growth hormone receptors (GHR(tot) and GHR(1A)) was also decreased (P<0.05). Therefore, the irreversible glucose loss resulted in a partial 'uncoupling' of the somatotrophic axis, as no increase in plasma GH levels occurred although plasma IGF-I levels, hepatic IGF-I mRNA declined, and the abundance of liver GH receptor mRNA declined.  相似文献   

17.
α-酮戊二酸对脂多糖应激断奶仔猪生长抑制的缓解作用   总被引：4，自引：1，他引：3  
试验用大肠杆菌脂多糖(LPS)多次刺激断奶仔猪建立应激模型,研究α-酮戊二酸(AKG)对断奶仔猪的生长性能和血浆激素水平的影响,探讨AKG能否缓解仔猪应激反应.选用24头健康断奶仔猪(杜洛克×长白×大白,体重(7.25±0.23)kg),随机分成3个组(空白对照组、应激对照组和AKG组),每组8个重复,每个重复1头猪.2个对照组饲喂基础日粮+1%淀粉,AKG组饲喂基础日粮+1%AKG,在试验第10天、第12天、第14天和第16天分别在应激对照组和AKG组仔猪的腹膜注射80 μg/kg LPS.试验结果显示:(1)试验第1～9天,未注射LPS时,AKG组平均日增重分别比空白对照组和应激对照组提高30.0%(P<0.05)和31.1%(P<0.05),料重比降低12.4%(P<0.05)和12.8%(P<0.05);试验第10～16天(注射LPS),应激对照组与空白对照组相比平均日增重降低28.8%(P<0.05),料重比升高16.8%(P<0.05),但AKG组的平均日增重和料重比与空白对照组相比无显著性差异(P>0.05);(2)与空白对照组相比,试验第10天,首次LPS刺激后,应激对照组的血浆胰岛素样生长因子(IGF-I)水平降低22.7%(P<0.05),而AKG组无显著变化(P>0.05);试验第16天,多次LPS刺激后,与空白对照组比较,应激对照组的IGF-I和胰岛素(INS)水平分别降低21.2%(P<0.05)和25.7%(P<0.05),而AKG组无显著变化(P>0.05).结果表明,日粮中添加1%AKG能显著缓解LPS应激对杜×长×大断奶仔猪生长的负影响.  相似文献   

18.
1. Sexed broiler-type chicks were raised either under a continuous (CON) 23 h light (L) and 1 h dark (D) schedule or an increasing photoperiod (INC). From 5 to 11 d of age birds were fed either: ad libitum (AL), energy intake (kJ ME) restricted to 9.414 x gBW0.67 (R1) or energy intake (kJ ME) restricted to 6.276 x gBW0.67 (R2). 2. Blood samples were taken at 4, 7, 11, 14 d of age and weekly thereafter to 49 d of age. Plasma thyroxine (T4), triiodothyronine (T3), insulin-like growth factor-I (IGF-I) and insulin were determined. 3. CON birds had elevated plasma T3 concentrations to 21 d of age, and greater plasma T4 concentrations at 11 and 21 d of age concurrent with greater food intake. Elevated plasma T3 concentrations in INC birds at 28 d of age coincided with lower plasma IGF-I concentrations at a time when growth and food intake were greater than CON birds. 4. Food restriction elevated plasma insulin and T4 but depressed plasma T3 and IGF-I. Plasma T3 was greater for food-restricted birds at 21 d of age, but subsequently, was generally lower than ad libitum-fed birds which may account for a lack of complete 'catch-up' in growth. 5. Plasma T3 was higher in females at 11 d of age when growth was equivalent for both sexes. From 28 to 42 d, when sex differences in growth became most apparent, plasma T3 was greater in males.  相似文献   

19.
Prepubertal Friesian heifer calves (n = 24, initial BW = 195 +/- 5 kg) were assigned to a 2 x 2 factorial block design and used to evaluate the effects of daily GH treatment (0 or 15 mg/d) at either a low or a high feeding level in a 5-wk treatment period on endocrine measurements, hormone receptors, muscle growth, and overall performance. In the pretreatment period, a low feeding level was employed for all calves. During the treatment period, animals at the low feeding level had free access to a roughage-based mixture, whereas animals at the high feeding level had free access to a concentrate mixture and were offered 2 kg/d of the roughage-based mixture. Blood samples were collected weekly starting 3 wk before treatment. Longissimus (LM) and supraspinatus (SS) muscles were obtained at slaughter. Metabolizable energy intake was 81% higher, digestible CP intake was 140% higher, and ADG was 115% higher (all P < 0.001) at the high vs. low feeding level. Feed (DMI, ME, and protein) intake was not affected by GH treatment, but ADG was 18% higher (P < 0.13) in GH-treated than in control heifers at both feeding levels. Although of different magnitudes, the muscle anabolic effects of GH treatment and high vs. low feeding level were additive, and both treatments increased carcass weights (P < 0.02 and P < 0.001, respectively), LM (P < 0.05 and P < 0.001), and SS (P < 0.06 and P < 0.003). The anabolic effect of GH treatment was similar in both muscles, whereas the effect of feeding level was most pronounced in LM. Overall, GH treatment increased plasma GH, IGF-I (both P < 0.001), and IGFBP-3 (P < 0.02); however, GH treatment increased total IGF-I, free IGF-I, and IGFBP-3, and decreased IGFBP-2 mainly at the high feeding level (GH x feeding level interaction; P < 0.02, 0.01, 0.03, and 0.10, respectively). The high feeding level increased insulin, free and total IGF-I, and IGFBP-3 (all P < 0.001), but decreased GH and IGFBP-2 (both P < 0.001). High feeding increased type-1 IGF receptor density (P < 0.02), mainly in LM, in accordance with the largest anabolic response in this muscle, whereas GH treatment had no effect on type-1 IGF receptors. The results suggest that in skeletal muscle, the anabolic effects of exogenous GH are related to endocrine changes in the GH-IGF axis, whereas the effects of feeding level also seem to rely on IGF receptor density in the muscles.  相似文献   

20.
The influence of age, sex and castration on plasma concentrations of insulin-like growth factor-I (IGF-I) and other metabolic hormones related to growth was studied in cattle. Plasma was sampled from bulls, steers, heifers, and ovariectomized heifers at 20-min intervals for 12 hr at 5, 8, 12, and 15 mo of age. Plasma samples from each animal taken during each 12-hr period were composited for analysis of IGF-I, testosterone, total estrogens, thyroxine, triiodothyronine, insulin, and glucose. The mean plasma IGF-I concentration in all cattle increased from 61.6 to 158.6 ng/ml as the animals aged (p less than .01). Over all ages, bulls had greater concentrations of IGF-I than steers, heifers, or ovariectomized heifers (P less than .01). Bulls also had higher concentrations of testosterone (P less than .01) and total estrogens (P less than .01). Triiodothyronine concentration was greater in ovariectomized heifers than in bulls (P less than .01) or steers (P less than .05). Females had higher concentrations of thyroxine than males (P less than .01). Concentrations of triiodothyronine in the cattle were greater (P less than .01) during the winter and early spring as compared with the summer. Concentrations of insulin and glucose were not influenced by sex or castration; however, insulin increased in all cattle with age (P less than .01). The mean increase in IGF-I concentration with age within each of the four groups was associated with an increase in concentration of plasma insulin but the differences due to sex were not related to differences in insulin.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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