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毛发生长周期 总被引：1，自引：0，他引：1
宋瑞超 《畜牧兽医科技信息》2012,(1):21-22
大多数动物的毛发生长呈现一种循环性变化,生长大致可分为三个时期,即毛发生长初期、毛发生长中期和毛发生长末期。本文对毛囊形成、毛发周期学说、毛发生长不同时期的特征进行了综述。 相似文献
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l 试验目的华中地区四季分明,夏季炎热,冬季寒冷,最低温度-8℃,持续期长达2～4个月,冬季在敞开式猪舍养猪,增重慢,效益低.本试验目的通过卷帘布封闭猪舍,利用猪自身热量保暖,探索适宜华中地区生长猪舍的最佳设计. 相似文献
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洛克沙胂对生长猪生长性能的影响田河万熙卿李德发吴金龙顾赛红（沈阳农业大学畜牧兽医学院·沈阳东陵·１１０１６１）（农业部饲料工业中心砷是动物必需的微量元素,广泛分布于体组织和体液中。研究表明,缺砷可导致动物生长缓慢,繁殖性能下降。目前,国收稿日期：１９... 相似文献
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对60头大约克夏从70～190日龄,每隔15d测定体重和背膘厚,分析其生长发育规律。结果表明:①大约克夏生长肥育期的各阶段日龄与体重间的相关系数r≥0.67(P<0.0001)。②Logistic模型和Compertz模型均可拟合大约克夏在生长肥育期的生长曲线(P<0.0001),但Logistic模型(R2=0.9967)优于Compertz模型(R2=0.9694)。③大约克夏130￣160日龄间的背膘厚度与体重保持极小的比值(约0.11),160日龄前背膘厚的分化生长率小于1(0.2653￣0.7711);大约克夏190日龄时体重为119.31kg,背膘厚为14.59mm。 相似文献
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小肽添加剂对生长猪生长性能的影响 总被引：2，自引：0，他引：2
试验研究三种不同的小肽添加剂制品对生长猪生长性能的影响。试验选用72头初始体重在(34.64±8.32)kg的杜×长×大三元阉公猪,随机分为4个处理,每个处理6个重复,每个重复3头猪试验各组分别饲喂基础日粮(对照组),基础日粮加100mg/kg小肽A(小肽A组),基础日粮加100mg/kg小肽B(小肽B组),基础日粮加50mg/kg小肽C(小肽C组),试验期28d。测定其对生长猪的生长性能的影响,结果表明,与对照组相比,小肽A组、小肽B组和小肽C组的生长猪的平均采食量分别提高了9.8%、7.0%和12.5%(P0.05),平均日增重分别提高了15.8%、12.8%和21.7%(P0.05),料肉比分别降低了5.1%、6.3%和8.5%(P0.05)。 相似文献
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洛克沙胂对生长猪生长性能的影响 总被引：2，自引：0，他引：2
本试验研究日粮中添加不同剂量的洛克沙胂（４０ｍｇ／ｋｇ、５０ｍｇ／ｋｇ）、喹乙醇（５０ｍｇ／ｋｇ）和洛克沙胂（５０ｍｇ／ｋｇ）＋喹乙醇（５０ｍｇ／ｋｇ）对生长猪生长性能的影响。试验结果表明,不同剂量洛克沙胂组、喹乙醇组及洛克沙胂＋喹乙醇组的日增重明显优于对照组（Ｐ＜０．０５）;４０ｍｇ／ｋｇ与５０ｍｇ／ｋｇ洛克沙胂和５０ｍｇ／ｋｇ喹乙醇＋５０ｍｇ／ｋｇ洛克沙胂三组的料肉比也显著的低于对照组（Ｐ＜０．０５）;从经济效益上分析,生长猪日粮中添加４０ｍｇ／ｋｇ洛克沙胂的经济效益较好。 相似文献
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长白猪生长肥育期生长规律的研究 总被引：1，自引：0，他引：1
对34头长白猪从70日龄到190日龄,每隔15天测定体重和背膘厚,分析其生长发育规律。结果表明:(1)长白猪生长肥育期的各个日龄体重间存在较大的相关(r≥0.54,P<0.01);(2)Logistic模型、Bertanlanffy模型和Gompertz模型均可拟合长白猪在生长肥育期的生长曲线(P<0.01),但Logistic模型(R2=0.995)优于其他模型(R2=0.994、0.988);(3)长白猪160日龄时的背膘厚度与体重的比值最小(0.110);160日龄前背膘厚的分化生长率小于1(0.213~0.931);长白猪190日龄时体重为117.78 kg、背膘厚为13.35 mm。 相似文献
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禽类生长轴的发育及其对生长的调节 总被引：15，自引：0，他引：15
长期以来,科学家们对禽类胚胎的内分泌学作了大量的研究,主要集中在以下几个方面：１）内分泌腺的发育,包括各种激素分泌细胞的发生、分化和成熟;２）细胞内合成激素的细胞器的发育;３）内分泌细胞对促泌素应答能力的获得和靶器官受体的发育及受体后信号传导机制的建立;４）调控系统的发育,包括神经的发生,内分泌腺上神经的分布,以及神经内分泌系统的发育。本综述将重点讨论与禽类生长密切相关的下丘脑垂体生长轴的发育及其在胚胎和早期发育过程中的作用。１ 概述动物的生长是一个复杂的过程,它由内因和外因共同决定的。外因… 相似文献
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本试验旨在研究日粮中添加不同比例棕榈粕对生长猪生长性能的影响。试验选取健康状况良好,胎次相近,平均体重(32.13依2.13)kg的杜长大三元杂交商品猪120头,随机分为4组,每组5个重复,每个重复6头猪。对照组饲喂基础日粮,试验组分别饲喂4%、7%、10%棕榈粕日粮。各组环境条件一致,自由采食和饮水,按照常规饲养管理进行,预饲期7天,试验期26天。结果显示院随着棕榈粕添加量(<7%)的增加,生长猪平均日采食量和平均日增重逐渐提高。7%棕榈粕组平均日采食量显著高于对照组(P<0.05),而4%棕榈粕组与对照组差异不显著(P>0.05);与对照组相比,4%棕榈粕组和7%棕榈粕组平均日增重均有升高的趋势但无明显差异(P>0.05)。当棕榈粕添加量达到10%时,平均日采食量和平均日增重比7%棕榈粕组显著降低,基本与对照组持平,且10%棕榈粕组料重比显著高于对照组(P<0.05)。因此,在生长猪(30kg)日粮中添加4%-7%棕榈粕可促进猪只采食量和生长性能,而当棕榈粕添加量达到10%时,会影响生长猪的采食量和生长性能。 相似文献
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Stimulation of pig growth performance by porcine growth hormone and growth hormone-releasing factor 总被引：10，自引：0，他引：10
T D Etherton J P Wiggins C S Chung C M Evock J F Rebhun P E Walton 《Journal of animal science》1986,63(5):1389-1399
The current study was undertaken to determine the effects of human growth hormone-releasing factor [hpGRF-(1-44)-NH2] on growth performance in pigs and whether this response was comparable to exogenous porcine growth hormone (pGH) treatment. Preliminary studies were conducted to determine if GRF increased plasma GH concentration after iv and im injection and the nature of the dose response. Growth hormone-releasing factor stimulated the release of pGH in a dose-dependent fashion, although the individual responses varied widely among pigs. The results from the im study were used to determine the dose of GRF to use for a 30-d growth trial. Thirty-six Yorkshire-Duroc barrows (initial wt 50 kg) were randomly allotted to one of three experimental groups (C = control, GRF and pGH). Pigs were treated daily with 30 micrograms of GRF/kg body weight by im injection in the neck. Pigs treated with pGH were also given 30 micrograms/kg body weight by im injection. Growth rate was increased 10% by pGH vs C pigs (P less than .05). Growth rate was not affected by GRF; however, hot and chilled carcass weights were increased 5% vs C pigs (P less than .05). On an absolute basis, adipose tissue mass was unaffected by pGH or GRF. Carcass lipid (percent of soft-tissue mass) was decreased 13% by GRF (P less than .05) and 18% by pGH (P less than .05). Muscle mass was significantly increased by pGH but not by GRF. There was a trend for feed efficiency to be improved by GRF; however, this was not different from control pigs. In contrast, pGH increased feed efficiency 19% vs control pigs (P less than .05). Chronic administration of GRF increased anterior pituitary weight but did not affect pituitary GH content or concentration. When blood was taken 3 h post-injection, both GRF- and pGH-treated pigs had lower blood-urea nitrogen concentrations. Serum glucose was significantly elevated by both GRF and pGH treatment. This was associated with an elevation in serum insulin. These results indicate that increasing the GH concentration in blood by either exogenous GH or GRF enhances growth performance. The effects of pGH were more marked than for GRF. Further studies are needed to determine the optimal dose of GRF to administer in growth trials and the appropriate pattern of GRF administration in order to determine whether GRF will enhance pig growth performance to the extent that exogenous pGH does. 相似文献
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Stimulation of swine growth by porcine growth hormone 总被引：7，自引：0，他引：7
Highly purified porcine growth hormone (pGH; USDA-B1) was administered by im injection (22 micrograms X kg body weight-1 X d-1) to rapidly growing Yorkshire barrows for 30 d. Growth hormone significantly increased growth rate (10%), feed efficiency (4%), cartilage growth and muscle mass. However, pGH did not affect carcass adipose tissue mass. Intramuscular lipid content of the longissimus was increased 50% by pGH administration. Plasma pGH concentration was elevated (7- to 11-fold) for 3 to 5 h post-injection. Chronic administration of pGH depressed pituitary GH content and concentration approximately 45%. No GH antibodies were detected in the plasma of GH-treated swine. Plasma somatomedin-C concentration was increased 55% by GH treatment 3 h post-injection. Plasma glucose and insulin concentrations were both significantly increased in GH-treated swine, suggesting that the animals had developed a state of insulin resistance. Plasma-free fatty acid concentration tended to be higher in GH-treated animals. Treatment of swine with pGH significantly decreased plasma blood urea nitrogen. Assessment of animal health during the trial and postmortem indicated that pGH administration did not have any adverse effects. In summary, treatment of young, rapidly growing swine with pGH stimulated growth performance without affecting animal health or inducing the production of GH antibodies. 相似文献
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1. The concentrations of circulating GH were low in 1‐week‐old birds (male plasma pool 30 ng/ml, female 32 ng/ml), reached a maximum at 7 weeks in male birds (142 ± 26 SEM ng/ml) or 4 weeks in females (185 ± 32 ng/ml) and then decreased to 17.3 ± 2–8 ng/ml in males and 8?7 ± 0–6 ng/ml in females at 17 weeks.
2. Significant inverse correlations between GH concentration and age or body weight were found (male, r = —0–693), female, r = —0–623).
3. In males, but not females, the weekly increase in body weight was correlated with the plasma GH concentration (r = 0–291). 相似文献
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Kitagawa H Kitoh K Ito T Ohba Y Nishii N Katoh K Obara Y Motoi Y Sasaki Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(2):167-170
Serum concentrations of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) were determined in 5 calves in the same lineage with growth retardation. They had normal appetites, activities, body proportion, and laboratory test results. Calves with growth retardation had higher serum GH concentrations and lower serum IGF-I concentrations. These findings suggested defects in the GH-IGF-1 axis, such as in the GH-receptor. 相似文献
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E E Connor S M Barao L W Douglass S A Zinn G E Dahl 《Journal of animal science》1999,77(10):2736-2741
Development of practical, physiologically based methods that provide an early, yet accurate, evaluation of a bull's genetic merit could benefit the beef industry. The use of GH response to a single, acute dose of GHRH was evaluated as a predictor of future growth performance and carcass characteristics of weanling bulls. Fifty-six Angus bulls averaging 229 d (SD = 27) of age were administered three doses i.v. (0, 1.5, and 4.5 microg/100 kg BW) of human GHRH (1-29) analog in a Latin square design balanced for residual effects. Blood samples were collected via jugular catheter at -60, -45, -30, -15, 0, 5, 10, 15, 30, 45, 60, 90 and 120 min relative to GHRH injection. Serum concentrations of GH were plotted over time. Response to GHRH was calculated as the area under the GH response curve (AUC-GH) using the trapezoidal approximation. Relationships between AUC-GH, weaning weight adjusted to 205 d of age (205-d WW), and direct weaning weight EPD (WWEPD) versus age-adjusted BW (BWadj), ADG, and carcass measurements from a 140-d growth performance test were evaluated using simple linear regression. A positive correlation between AUC-GH and ADG and an inverse relationship between AUC-GH and carcass fat were observed. The present study provides evidence that AUC-GH is a better predictor of future growth performance in beef bulls than 205-d WW or WWEPD values. Thus, GH response to GHRH is associated with subsequent growth and may be a useful tool for sire selection in beef production. 相似文献
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T L Auchtung E E Connor S M Barao L W Douglass G E Dahl 《Journal of animal science》2001,79(6):1566-1572
The response of GH to GHRH at weaning is known to predict postweaning growth and body composition in beef bulls. The objective of this study was to determine whether GH response to a challenge of GHRH and plasma IGF-I can predict growth rate and body composition in the beef heifer. Growth hormone response to a challenge with two doses of GHRH was measured in 67 Angus heifers averaging 225 d of age (SD = 21) and 217 kg BW (SD = 32). Blood samples were collected at 0 and 10 min relative to an initial "clearance dose" (4.5 micrograms GHRH/100 kg BW) and again, 3 h later, relative to a challenge dose (1.5 or 4.5 micrograms GHRH/100 kg BW). Each animal received each of the two challenge doses, which were randomly assigned across 2 d of blood collection. Serum GH concentration was measured by RIA. Plasma was collected every 28 d during a 140-d growth test and assayed for IGF-I by RIA. Body weight was measured every 28 d and hip height was measured at weaning and at the end of a 140-d growth test. Average daily gain was calculated on d 140 of the growth test and body composition measurements were estimated by ultrasound 2 wk after completion of the growth test. Responses to the two GHRH challenges were dose-dependent (P < 0.05). Average daily gain tended to be related to GH response to the 1.5 micrograms GHRH/100 kg BW dose (R2 = 0.05; P = 0.06), but no relationship was observed at the 4.5 micrograms GHRH/100 kg BW dose (R2 = 0.00; P = 0.93). An inverse relationship (R2 = 0.06; P = 0.02) was observed between response to the 1.5 micrograms GHRH/100 kg BW dose and intramuscular fat percentage. Mean plasma IGF-I concentration was positively associated with ADG (R2 = 0.06; P < 0.01). Growth hormone response to GHRH is modestly related to body composition but not to ADG in weanling beef heifers and likely has limited use in evaluation of growth performance in replacement beef heifers. 相似文献
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