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1.
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   

2.
Twenty-four double-muscled Belgian White Blue bulls were assigned, according to body weight, to two groups with and without treatment with anabolic agents. Implants containing 140 mg trenbolone and 36 mg zeranol (Forplix) were inserted sc on the upper face of the ear flap. Plasma concentrations of testosterone and luteinizing hormone (LH) were determined at d 0, 30 and 60 of the experimental period. Mean testosterone levels at d 0 for treated and controls were, respectively, 2.1 and 1.7 ng/ml during the 10-h sampling period. At d 30 and 60, testosterone levels were strongly depressed in implanted bulls (.2 ng/ml) as compared with 2.5 and 1.7 ng/ml in control bulls (P less than .001 at d 30 and P less than .01 at d 60). Average plasma LH concentrations were identical in the two groups at d 0 and 60 (1.1 and 1.5 ng/ml, respectively), but showed a slight decrease at d 30 in the treated group (P less than .10). The pulsatile character of LH and testosterone profiles was abolished by the Forplix treatment. Luteinizing hormone-releasing hormone (LHRH) injection at d 0 was followed in both groups by an immediate and sharp increase in plasma LH concentrations. The LH response reached a maximal value between 20 to 40 min postinjection and then declined rapidly. On the contrary, Forplix treatment strongly reduced LH and testosterone responses to LHRH stimulation in treated animals. Average daily gain and feed to gain ratios were 1.087 +/- .127 and 7.52 +/- .32 kg, respectively, for the control bulls and 1.335 +/- .092 and 6.24 +/- .24 kg for the Forplix-treated bulls, thus clearly showing a beneficial effect of Forplix treatment.  相似文献   

3.
Concentrations of IGF-I and IGF-II, and IGF binding proteins (IGFBP) in serum and mammary gland secretions were surveyed during the dry period and early lactation of 30 Holstein cows. Although there was a threefold drop in the concentration of IGF-I in serum from the last week of the dry period to parturition (81 +/- 7 to 24 +/- 3 ng/ml, P less than .01), there was no significant change in serum IGF-II concentration during this period (150 +/- 17 vs 173 +/- 13 ng/ml, P greater than .05). Furthermore, a 57% increase in serum IGF-I was observed from the last week of lactation to the second week of drying off (100 +/- 5 to 157 +/- 8 ng/ml, P less than .05). Changes in serum IGF-II were not observed (126 +/- 11 vs 150 +/- 10 ng/ml, respectively; P greater than .05). Although IGF-I, IGF-II, and IGFBP concentrations in mammary secretions peaked 2 wk before parturition (2.95 +/- 1.1, 1.83 +/- .6, and 7.27 +/- .76 micrograms/ml, respectively), total output/quarter was highest in colostrum (394 +/- 119, 295 +/- 132, and 2,680 +/- 1,967 micrograms/quarter, respectively). Weekly milking of two individual quarters during the dry period did not affect (P greater than .05) IGF-I or IGF-II concentration (ng/ml) or total output (microgram/quarter) and milk yield in colostrum and milk (2 wk and 7 wk) compared with the ipsilateral quarter. The data support the hypothesis that IGF-I may be transported by the mammary gland epithelium. Furthermore, the secretion mechanisms of IGF-I, IGF-II, and IGFBP by the gland may be related to each other.  相似文献   

4.
The effects of dam parity, age at weaning, and preweaning diet were examined in the ontogeny of serum insulin-like growth factor-I (IGF-I) concentrations in foals. Foals born to 13 primiparous and 19 multiparous draft-cross mares were weighed and bled near birth. About one-half of the foals in each group were weaned early (about 13 wk old); the remaining foals were weaned late (about 16 wk of age). Pooled values for serum IGF-I concentrations between birth and 17 wk of age were higher (P < 0.065) for foals born to multiparous (386 ng/ml) than to primiparous mares (237.5 ng/ml). Colts (378 ng/ml) had higher (P < 0.05) serum IGF-I concentrations than fillies (254.5 ng/ml), regardless of dam parity. Colts (173.5 kg) also tended (P = 0.12) to be heavier than fillies (159.2 kg). Weaning, whether at 13 or 16 wk of age, reduced (P < 0.05) growth rates and serum IGF-I concentrations. Serum IGF-I values recovered to preweaning values within 1–3 wk postweaning concurrent to an improved weight gain. Fifteen 1-d-old foals in a second study were fed milk replacer for 7 wk and were compared with five foals that nursed their mares for 8 wk. During the first 2 wk, replacer-fed foals (0.46 kg/d) did not gain as rapidly (P < 0.03) as mare-nursed foals (1.73 kg/d). The associated serum IGF-I values for replacer foals (139.4 ng/ml) were lower (P < 0.0001) than values for mare-nursed foals (317.4 ng/ml). Despite similarity in gains for both groups thereafter, serum IGF-I concentrations of replacer-fed foals were only 36 and 60% of values obtained for mare-nursed foals at 8 (weaning) and 18 wk of age, respectively. The intrinsic differences between mare-nursed and milk-replacer foals in serum IGF-I concentrations persisted to 1 yr of age despite similarities in dietary management and body weight of the foals. At 1 yr of age, the serum IGF-I concentration of mare-nursed foals (1,203 ng/ml) was 48% higher than that of replacer-fed foals (815 ng/ml). These data indicate that dam parity, sex of foal, and preweaning nutrition affect the ontogeny of serum IGF-I concentration in the foal. The chronic, persistent difference in serum IGF-I values created by the early nutritional management of growing animals has implications in the interpretation of longitudinal serum IGF-I studies in all species.  相似文献   

5.
Plasma insulin-like growth factor-I (IGF-I) concentrations were monitored in Holstein females through different periods of their growth, lactation and after acute or chronic growth hormone-releasing factor (GRF) administration. Plasma samples were radioimmunoassayed using a human IGF-I antibody after a 24 hr incubation in a HCl(.1N)-glycine(.2M) buffer (pH 2). In a first study, IGF-I concentrations were measured in Holstein females of different ages and(or) stages of lactation (n = 6 per group). The IGF-I concentrations in newborn calves (102.0 +/- 11.3 ng/ml) markedly decreased (P less than .01) in 1 mo old animals (50.2 +/- 7.1 ng/ml), then increased (P less than .01) to 137.0 +/- 5.1 and 137.4 +/- 11.0 ng/ml in 6 and 10 mo old heifers, respectively. In dairy cows, IGF-I concentrations were low 24 hr post-partum (44.7 +/- 7.6 ng/ml) and then increased (P less than .05) to remain stable throughout lactation (91.3 +/- 4.9, 92.8 +/- 12.9, 96.1 +/- 7.6, 90.7 +/- 8.8 ng/ml at 2, 3, 6 and 9 mo of lactation, respectively). There was a further increase (P less than .05) to 113.7 +/- 3.1 ng/ml during the dry period. In a second trial, blood samples were collected from lactating dairy cows every 2 hr for 24 hr following a sc injection of saline (n = 4) or human (h) GRF (1-29)NH2 (10 micrograms/kg BW, n = 4). The IGF-I peak concentration was reached on average 10 hr after the GRF injection and was higher (P less than .01) in treated cows than in control cows (135.4 vs 86.9 +/- 16.2 ng/ml). In the last trial, daily sc injections of 10 micrograms of hGRF(1-29)NH2 per kg BW to dairy cows (252 days of lactation) for 57 days, which increased milk production by 14% (2 kg/day), also increased (P less than .01) IGF-I concentration: 127.1 +/- 5.3 and 118.0 +/- 1.6 vs 90.7 +/- 4.7 and 96.0 +/- 5.0 ng/ml on days 29 and 57 of treatment for treated (n = 9) and control (n = 8) cows, respectively. Thus, the IGF-I concentration in dairy cattle varies with age and stage of lactation, and is increased by GRF administration in lactating dairy cows.  相似文献   

6.
Mean concentrations and the occurrence of pulsatile release of luteinizing hormone (LH) were determined in 14-wk-old crossbred boars (50.5 +/- 1.5 kg) after bilateral or unilateral castration at 10 wk of age. Blood was collected at 10-min intervals for 5 h. Then gonadotropin releasing hormone (GnRH; 40 micrograms) was given and sampling was continued at 5-min intervals for 1 h. Compared with intact boars, bilateral castration increased (P less than .001) mean LH (982 +/- 56 vs 389 +/- 56 pg/ml), pulsatile releases of LH (7.0 +/- .6 vs 2.0 +/- .6 pulses/5 h) and LH pulse amplitude (617 +/- 29 vs 360 +/- 58 pg/ml). Unilaterally castrated boars did not differ from intact boars in any of the above measures of LH secretion. Testis weight increased more between 10 and 14 wk of age in the unilateral castrates than in the intact boars (432 +/- 42 vs 245 +/- 34%; P less than .05). Thus, compensatory hypertrophy occurred within 4 wk of castration. Plasma testosterone was lower for bilateral castrates than for intact animals (.1 +/- .8 vs 3.6 +/- .9 ng/ml; P less than .05) while unilateral castrates (3.8 +/- 1.0 ng/ml) and intact boars did not differ. Plasma estradiol concentrations in bilateral and unilateral castrates were not different from levels found in intact boars (1.8 +/- 1.8, 8.8 +/- 2.1 and 6.0 +/- 1.8 pg/ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
This study was designed to evaluate the ontogeny of serum IGF-I (SI) concentrations and its relationship to animal performance in a 140-d postweaning feeding trial. Ninety-eight progeny representing six sires (three high and three low feed conversion) and two sexes (43 bulls and 55 heifers) with ad libitum access to feed were allocated by sire and sex to monitor individual weights and pen feed consumption. Blood serum samples were obtained at the beginning of test (average age of 230 d) and every 28 d thereafter until each animal reached a fat thickness (estimated by sonoray) of 8.9 mm. Individual serum samples were acid-ethanol extracted and measured for IGF-I peptide by heterologous RIA. Serum IGF-I concentrations differed (P less than .10) between high (H) and low (L) feed conversion progeny groups at the end of the first 28-d period (125.12 vs 89.52 ng/ml) and tended to differ at the conclusion of the second 28-d period (P less than .15). Weight gains of H and L groups tended to differ in the second and third 28-d periods (P = .11 and .10, respectively). Serum IGF-I concentrations differed (P less than .05) between bulls and heifers for the first through fourth 28-d periods (P less than .01, P less than .05, P less than .10 and P less than .01, respectively). Phenotypic correlations indicated that pens with higher mean SI concentrations at the beginning of the test consumed less feed and had lower cumulative feed:gain ratios.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
Endocrine and metabolic changes during altered growth rates in beef cattle   总被引：2，自引：0，他引：2  
Eight steers from a group of 14 were fed ad libitum from 240 to 510 kg live weight, gaining at 1.4 +/- .2 kg/d. The six other steers were diet-restricted and grew at .37 +/- .09 kg/d from 240 to 307 kg, prior to ad libitum realimentation on the same diet to a final weight of 510 kg. Blood samples taken during the growth phases from both treatments were analyzed for insulin-like growth factor-I (IGF-I), triiodothyronine (T3), thyroxine (T4), glucose (GLU), nonesterified fatty acids (NEFA), and blood urea nitrogen (BUN) and (or) growth hormone (GH). During restricted growth, mean serum concentrations of GH were elevated (45.6 vs 23.4 ng/ml; P less than .05), serum concentrations of IGF-I decreased (108 vs 167 ng/ml; P less than .05) compared with control steers with ad libitum access to feed. Levels of T4 and GLU also were lower (P less than .05) during restricted than during normal growth. During early realimentation, levels of GLU (P less than .05), IGF-I (P less than .01), T4 and BUN (P less than .01) increased. Levels of T3 remained unchanged, whereas concentration of NEFA declined (P less than .001). Blood urea nitrogen decreased during early realimentation despite a large increase in diet protein intake and in protein storage, suggesting an increased efficiency of nitrogen use for protein synthesis. During realimentation, IGF-I levels rose above those of control steers and remained higher at the final weight of 510 kg (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
The objective of this study was to investigate the changes in muscle fiber bundles of cattle of different breeds during growth. Different numbers of muscle fibers are surrounded by connective tissue to form bundles macroscopically visible as meat fibers or meat grain, a common meat quality trait. To determine the influence of breed and age on morphological characteristics of muscle fiber bundles, 4 cattle breeds with different growth impetus and muscularity were reared and slaughtered under experimental conditions. German Angus, a typical beef cattle; Galloway, a smaller beef type; Holstein Friesian, a dairy type; and double-muscled Belgian Blue, an extreme type for muscle growth, were used. Between 5 and 15 bulls of each breed were slaughtered at 2, 4, 6, 12, or 24 mo of age, and slices of semitendinosus muscle were removed. Muscle structure characteristics were determined by computerized image analysis. During growth, the muscle cross-sectional area enlarged (P < 0.001) about 5-fold in double-muscled Belgian Blue bulls and about 4-fold in the other breeds. This was a result of the enlargement (P < 0.001) of primary bundles and muscle fibers. The bundle size was similar (P > or = 0.15) in bulls of German Angus and Galloway in all age groups and was doubled (P < 0.001) in double-muscled Belgian Blue animals from 4 mo of age on. The Holstein Friesian bulls had the smallest (P < 0.001) muscle fiber bundles at 24 mo of age. The number of muscle fibers per bundle and the number of bundles per muscle remained nearly constant (P > 0.05) during growth. This supports the existing view that the structure of the muscle is already fixed in prenatal life. The double-muscled Belgian Blue bulls showed a more than 2.5-fold greater (P < 0.001) number of muscle fibers per primary bundle compared with the other breeds investigated. The larger muscle fiber bundles led to a smaller amount of connective tissue per muscle area in double-muscled cattle. The coarser grain of meat in double-muscled Belgian Blue bulls and in older animals was not related to greater shear force values.  相似文献   

10.
In two experiments, 17-wk-old Holstein bulls exposed to 16 (Exp. 1) or 24 h (Exp. 2) of light daily were compared with bulls given 8 h of light. Blood was sampled at 30-min or 120-min intervals for 48 h at the beginning and again after 4 wk of light treatment. Melatonin concentrations varied episodically in serum, and means were 1.6-fold to 5.1-fold greater during darkness than during light periods. Continuous lighting abolished the nocturnal increase in concentrations of melatonin in three of four calves. Prolactin (PRL) was greater (P less than .05) in calves receiving 16 h (30.9 ng/ml of serum) than in calves receiving 8 h (7.0 ng/ml) of light daily. Prolactin was not different between calves receiving 24 or 8 h of light daily. In a third experiment, one pinealectomized (PX) and two sham PX (SPX) calves were exposed to continuous lighting and infused with melatonin for 16 h/d for 5 wk, and one PX and two SPX calves were infused for 8 h daily. Melatonin infusion increased average concentrations of melatonin in serum 7.2-fold to 18-fold above baseline concentrations. Duration of melatonin infusion did not affect PRL (21.0 vs 20.8 ng/ml of serum). Also, surgical treatment did not affect PRL concentrations. Similarly, in a fourth experiment, PRL in postpubertal heifers fed melatonin to mimic and 8L:16D photoperiod averaged 27.1 ng/ml of serum, which was not different from PRL in heifers receiving 16L:8D and fed vehicle (32.6 ng/ml). We conclude that PRL and melatonin are each affected by photoperiod but are not casually related in cattle.  相似文献   

11.
The dopamine antagonist metoclopramide (MC) was administered to steers grazing on endophyte-infected fescue. Yearling Angus steers (n = 24) were assigned randomly to pasture treatments including high (74%) and low (33%) endophyte levels and low (134 kg N.ha-1.yr-1) and high (335 kg N.ha-1.yr-1) N fertilization rates. One steer of the pair in each paddock (n = 12) received MC, whereas the other received sucrose (S) (15 mg/kg body weight, orally, three times a week for 10 wk). Blood for basal and maximal TRH-stimulated serum prolactin (PRL) concentrations was obtained before animals grazed fescue, after grazing for 1 mo, and after 3, 6 and 9 wk of animal treatment. Grazing endophyte-infected fescue decreased (P less than .05) basal serum PRL concentrations (less than 1.0 vs 5.3 ng/ml, high vs low endophyte). Basal serum PRL increased after 3, 6 and 9 wk of MC treatment (58.1 vs 5.4, 46.0 vs 12.0 and 50.8 vs 16.9 ng/ml, MC vs sucrose, respectively). After 6 wk of animal treatments, MC increased (P less than .05) serum cholesterol (84.7 vs 60.8 mg/dl, MC vs S). Animals treated with MC spent more (P less than .05) time between 1200 and 1600 grazing (22.4% vs 6.2%, MC vs S respectively) and had faster ADG (.314 vs .150 kg/d, MC vs S). The results implicate dopaminergic processes in fescue toxicosis.  相似文献   

12.
Insulin-like growth factor-I (IGF-I) is an important factor for germ cell development and maturation of spermatozoa. Actions of IGFs are modulated by IGF-binding proteins (IGFBPs) that may, depending on their concentration and site of expression, inhibit or enhance effects of IGF-I. We characterized IGFs and IGFBPs in seminal plasma from bulls routinely used for artificial insemination (AI) and from bulls producing poor-quality semen (low mass and individual motility of spermatozoa). IGFs were measured by specific radioimmunoassay in 22 samples of seminal plasma from nine different AI bulls with high (> 76.8%), average (72.8-73.4%), or low (< 69.5%) nonreturn rate (NRR). IGF-I and IGF-II levels were 144 +/- 9 ng/ml (mean +/- SE; range, 79-238 ng/ml) and 144 +/- 10 ng/ml (range, 55-221 ng/ml), respectively, and did not correlate with NRRs. IGF-I concentrations in seminal plasma from bulls producing poor-quality semen (n = 10) were significantly (P < 0.05) greater (194 +/- 26 ng/ml; range, 94-370 ng/ml), whereas IGF-II levels were significantly (P < 0.05) lower (93 +/- 17 ng/ml; range, 38-183 ng/ml) than in AI bulls. Ligand blot analysis of seminal plasma for IGFBPs revealed the presence of a 38-/45-kDa doublet band and a 30-kDa IGFBP. These IGFBPs were identified as IGFBP-3 and IGFBP-5, respectively, by immunoprecipitation using specific antibodies. In addition, a low amount of IGFBP-4 was detected in bovine seminal plasma by immunoprecipitation. There was a marked difference in the activity of IGFBPs between individual bulls, with a relatively small within-bull variance. The differences in IGFBP activities did not correlate with the fertilization capacity of the bulls in vivo or in vitro nor with immunoreactive IGF-I and IGF-II levels in seminal plasma. Our results demonstrate the presence of IGFBPs in bovine seminal plasma. In contrast to human seminal plasma, high activity of IGFBP-3 was detected in seminal plasma of some bulls, suggesting species-specific regulation of IGFBP activity by proteases.  相似文献   

13.
Sixteen yearling Angus bulls were randomly assigned to one of two temperature-controlled chambers to determine the effects of elevated ambient temperature on body functions and semen characteristics. After 8 wk adjustment at 23 C, eight heat-stressed bulls were exposed to 35 +/- 1 C for 8 h and 31 +/- 1 C for 16 h during each 24-h period, and eight control bulls were maintained at 23 +/- 1 C for 8 wk. Then all bulls were exposed to 23 C for 8 wk. Bulls were fed so that both control and stressed bulls gained at similar rates (.58 kg/d). Semen was collected with an artificial vagina twice weekly before, during and after heat stress. During treatment, the respiratory rate of stressed bulls was greater (P less than .001) than that of control bulls (54.2 +/- 1.5, 29.9 +/- 1.5 breaths/min, respectively). Rectal temperatures were increased (P less than .01) from 38.2 +/- .1 to 38.7 +/- .1 C and water consumption was increased by 35% in stressed bulls when compared with controls. Semen volume was not altered by treatment, but percentage of motile sperm decreased (P less than .01) in stressed bulls by 2 wk after the start of heat treatment. Sperm motility of stressed bulls returned to normal values 8 wk after the end of heat treatment. Similarly, the percentage of aged acrosomes on sperm from stressed bulls increased (P less than .01) by the second week of treatment and remained greater than that of controls throughout the stress period.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

14.
Serum samples and BW were obtained from 2-yr-old beef heifers, pregnancy with either single (SF, n = 12) or twin (TF, n = 7) fetuses, at 7-d intervals from d 190 of gestation until calving. Serum insulin-like growth factor I (IGF-I) concentrations of SF heifers gradually declined from d 190 (69.9 +/- 1.0 ng/ml) to d 263 (55.6 +/- .8 ng/ml), then exhibited a slight increase by d 277 (63.4 +/- 1.1 ng/ml). Serum IGF-I concentrations of TF heifers essentially paralleled, yet were lower (P less than .05) than, concentrations in SF heifers for all days tested except d 197 and 205. The SF heifers pregnant with heifer fetuses (n = 6) had higher IGF-I concentrations (P less than .1) than heifers pregnant with bull fetuses (n = 6) for all days tested except d 214 and 235. Instantaneous absolute growth rate (IGR) of SF heifers declined from 1.485 kg/d at d 190 to .257 kg/d by d 277. Rate of decline in IGR of TF heifers was much greater (P less than .0001). Correlations between serum IGF-I concentrations and IGR for SF and TF heifers were .79 (P less than .001) and .59 (P less than .05), respectively. These data suggest that number and sex of fetus influence maternal concentrations of IGF-I and that the combined growth rate of the dam and conceptus during gestation is related to serum IGF-I concentration.  相似文献   

15.
The growth rate of the young pig is generally much less than its potential and may be constrained by endocrine status as well as by nutrient intake. The aim of this study was to determine whether porcine somatotropin (pST) could increase growth in the nursing pig. Fourteen sows nursing litters of 6 (n = 7) or 12 (n = 7) piglets were utilized to establish a high and low plane of nutrition for sucking pigs. On Day 4 of lactation, the median two male pigs from each litter were randomly allocated to one of two doses of pST (0 or 60 micrograms/kg/d) until weaning on Day 31. Pigs were bled on Days 4, 13, 22, and 31 of lactation and the plasma was analyzed for insulin-like growth factor (IGF)-I, IGF-II, and IGF binding protein-3 (IGFBP-3). Pigs were weaned into conventional accommodation and further weighed on Days 63, 91, and 119. Pigs from litters of 6 grew more quickly and weighed 2.2 kg (P = 0.01) and 3.5 kg (P = 0.04) more than pigs from litters of 12 at 31 and 63 d of age, respectively. There was no effect of pST on preweaning growth of sucking pigs (261 vs. 258 g/d, P = 0.68), although growth rate increased in the final 3 d before weaning at 31 d (241 vs. 294 g/d, P = 0.01). IGFBP-3 was greater (1.09 vs. 0.78 micrograms/ml, P < 0.001), whereas IGF-I tended to be greater (206 vs. 176 ng/ml, P = 0.14), in pigs from the small litters. There was no effect of pST on plasma IGF-I (182 vs. 195 ng/ml, P = 0.454) or IGFBP-3 (0.93 vs. 0.94 microgram/ml, P = 0.85) concentrations. Plasma IGF-I and IGFBP-3 were highly correlated with the growth rate of nursing pigs (R = 0.638 and 0.756, respectively). There were no effects of pST (340 vs. 328 ng/ml, P = 0.48) or litter size (336 vs. 333 ng/ml, P = 0.88) on IGF-II. In conclusion, pST had no little or no effect on growth performance or plasma IGF-I, IGF-II, or IGFBP-3 in sucking pigs on either a high or low plane of nutrition.  相似文献   

16.
The effect of dietary energy restriction on serum insulin, insulin-like growth factor I (IGF-I), growth hormone, (GH), cortisol, plasma urea nitrogen (PUN) and nonesterified fatty acid (NEFA) concentrations was examined. Angus bulls and steers (10 mo) were allotted to two groups of 12 animals and assigned a treatment order. In a switchback design, animals in order 1 were fed a high grain diet, then fasted, while order 2 animals were fasted, and then fed. Animals were allowed 60 hr to acclimate between treatments. Serum and plasma were obtained at 20 min intervals and 60 min, respectively, for 6 hr after feeding and for the last 6 hr of a 30 hr fast. Serum was assayed for insulin, IGF-I, GH, and cortisol (total and free). Plasma was assayed for PUN and NEFA. Mean insulin (ng/ml) differed between fed (.95 +/- .08) and fasted (.26 +/- .08) animals (P less than 01). Both mean total and free cortisol (ng/ml) were lower in fed (11.48 +/- .99) (1.06 +/- .12) than in fasted (17.10 +/- .93) (1.62 +/- .12) animals, respectively (P less than .01). Animals in order 1 differed in mean IGF-I (ng/ml) between fed (199.0 +/- 8.0) and fasted (116.5 +/- 7.2) treatments (P less than .01). Mean IGF-I for animals in order 2 was 146.7 +/- 7.2 in fed and 213.9 +/- 7.2 in fasted animals (P less than .01). Mean GH did not differ between treatments. Mean PUN and NEFA were higher in fasted than in fed animals (P less than .01). Except for % free cortisol (P less than .05), the hormones did not differ between bulls and steers.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
Sixty-three Angus x Simmental calves were allotted to a bull or a steer group based on sire, birth date, and birth weight to determine effects of castration status on performance, carcass characteristics, and circulating insulin-like growth factor I (IGF-I) concentrations in early-weaned cattle. At 75 d of age, calves in the steer group were castrated. Calves were not creep-fed prior to weaning. All calves were weaned and weighed at an average age of 115 d and transported by truck to the OARDC feedlot in Wooster, OH. Performance and carcass characteristics were measured in three phases. Phase 1 was from 115 to 200 d of age, phase 2 was from 201 to 277 d of age, and phase 3 was from 278 d of age to slaughter. Before implantation, four bulls and four steers were selected for serial slaughter and carcass evaluation. Steers were implanted with Synovex-C at 130 d of age and with Revalor-S at 200 and 277 d of age. Serum samples were collected from all calves on the day of implantation, 28 and 42 d after implantation, and at slaughter and analyzed for circulating IGF-I concentration. Bulls gained 9.7% faster (1.75 vs 1.60 kg/d; P < 0.01), consumed 25 kg more DM (521 vs 496 kg; P = 0.11), and were 3.3% more efficient (282 vs 273 g/kg, P < 0.10) than steers in phase 1. However, steers gained 10.5% faster (1.62 vs 1.46 kg/d; P < 0.02), consumed similar amounts of DM, and were 6.5% more efficient than bulls (214 vs 201 g/kg; P < 0.06) in phase 2. Overall gains and efficiency were similar between bulls and steers; however, bulls consumed 140 kg more DM (P < 0.05), were 27 kg heavier (P < 0.05), and had to stay in the feedlot 18 more days (P < 0.05) than steers to achieve a similar amount of fat thickness. Implanted steers had greater concentrations of circulating IGF-I than bulls (P < 0.01), and the pattern of IGF-I concentration over time was affected by castration status (castration status x time interaction; P < 0.01). Synovex-C had a lower impact on circulating IGF-I concentration (implant effect, P < 0.01) than either Revalor-S implant. Eighty-five percent of both bulls and steers had marbling scores sufficient to grade low Choice or better. Bulls achieved their target fat thickness later, increased muscle growth, and deposited fat more favorably than steers, possibly due to a gradual increase in IGF-I concentration as the testicles grew rather than the large fluctuations in IGF-I concentration observed in steers following implantation.  相似文献   

18.
Bovine GH and testosterone profiles were determined in plasma collected at 20 min intervals during 3 hr bleeding periods on day 25 of life and every 15 days thereafter in six intact (I) Holstein bull calves and in six others which had been hemiorchidectomized (HO) at 10 days of age. In I bulls average plasma GH concentrations varied between 7.9 and 14.5 ng/ml (P greater than 0.05) until 130 days of age, after which the GH level gradually rose (P = 0.007) to a maximum of 19.4 ng/ml on day 205 of life. Episodic release of GH was apparent in 55 day-old and older I bulls and in HO bulls of all ages. Plasma GH concentrations in HO bulls were higher than in I bulls 15 and 30 days after surgery (P = 0.07), at which times the levels in HO bulls averaged 19.6 and 22.5 ng/ml and in I bulls 10.3 and 10.2 ng/ml, respectively. Plasma GH in HO bulls again exceeded that of I bulls at ages of 130-190 days (P = 0.04). Plasma testosterone was virtually nondetectable before 130 days of age in I bulls but thereafter exhibited the typical episodic pattern. In HO bulls, plasma testosterone concentrations began to rise 15 to 30 days before those in I bulls, resulting in an age X treatment interaction (P less than 0.0001). Furthermore, average testosterone levels were higher (P = 0.07) in HO than I bulls at 235 and 250 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
To determine influences of insulin and body condition on follicular growth, prepuberal gilts (n = 16) treated with pregnant mare's serum gonadotropin (PMSG) were used in a 2 X 2 factorial experiment with main effects of insulin (0 or .4 IU/kg every 12 h beginning at 1800 on the day before PMSG) and backfat depth (moderate, 25 +/- .8; high, 32 +/- .7 mm; P less than .0001). Body weights were similar. Blood sampling was at 6-h intervals for analyses of LH, FSH, growth hormone (GH), glucagon, cortisol, insulin, insulin-like growth factor-I (IGF-I), plasma urea nitrogen (PUN), nonesterified fatty acids (NEFA), testosterone, estradiol-17 beta, and progesterone. Ovaries were removed 75 h after PMSG treatment, and visible small (less than or equal to 3 mm), medium (4 to 6 mm), large (greater than or equal to 7 mm), and macroscopically atretic follicles were counted. Administration of insulin increased IGF-I in fluid of medium follicles (108.8 vs 60.7 ng/ml; SEM = 13.3; P less than .05). Neither insulin nor fatness affected hCG binding by granulosa cells (12.5 +/- 1.6 ng/10(6) cells) or numbers of large (16.7 +/- 2.6) and medium (10.4 +/- 2.3) follicles. However, insulin increased the number of small follicles (58.9 vs 29.9; SEM = 9.7; P less than .05) and reduced the number of atretic follicles (3.8 vs 11.3; SEM = 1.1; P less than .05). The predominant effect of insulin on reducing number of atretic follicles was in the small size class (.6 vs 6.9; SEM = .6, P less than .01). Follicular fluid estradiol and progesterone were not affected by treatments; however, testosterone concentrations in large follicles were lower in gilts with higher backfat (32.5 vs 59.9 ng/ml; SEM = 4.0; P less than .05). Systemic LH, FSH, glucagon, cortisol, PUN, NEFA, estradiol, and testosterone were not affected by insulin or level of feeding. However, GH was lower in gilts that had higher backfat (overall average of 3.2 vs 2.8 ng/ml; SEM = .1; P less than .05). Insulin reduced atresia and altered intrafollicular IGF-I independently of body condition and without sustained effects on other hormones.  相似文献   

20.
Four Belgian Blue double-muscled type (BBDM) bulls, four Belgian Blue dual-purpose type (BBDP) bulls and four Holstein bulls were used in a fattening trial in order to relate differences in the extent of muscle development and adiposity to differences in digestibility, endocrine status, protein and lipid metabolism. The larger muscle development in BBDM animals was associated with a trend to higher nitrogen retention, higher food conversion efficiency (p<0.05) and lower apparent digestibility (p<0.05). No difference was found between the groups for plasma glucose concentration. Higher creatinine, lower -amino nitrogen, lower triglycerides and higher non-esterified fatty acid plasma levels were observed in BBDM as compared to Holstein bulls (p<0.05), the BBDP group being intermediate. A trend to a higher cholesterol plasma level was found in BBDM animals. There was no difference between the three groups in plasma fatty acid composition, except for the C14:0 content. Some of the differences in plasma metabolites were related to carcass composition and endocrine regulation, a decrease in muscle development and an increase in adiposity being associated with lower growth hormone production (p<0.05) and higher insulin (p<0.05) and IGF1 secretions. The insulin/growth hormone ratio at the end of the fattening period was 0.0011, 0.0018 and 0.0069 in BBDM, BBDP and Holstein bulls, respectively, and was directly associated with fat deposition.Abbreviations BBDM Belgian Blue breed double-muscled type - BBDP Belgian Blue breed dual-purpose type - IGF1 insulin-like growth factor 1 - NEFA non-esterified fatty acids - T3 triiodothyronin - T4 tetraiodothyronin  相似文献   

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