褪黑激素对非生绒期内蒙古白绒山羊体成分的影响

作者从体成分的角度研究了褪黑激素对内蒙古白绒山羊体成分的影响,绒山羊在非生绒期埋植褪黑激素,除了促进长绒外,对体成分也有较大影响.试验结果表明,埋植褪黑激素可以显著增加绒山羊的体脂肪含量,达到24.1%,比不埋植组增加8.31%;而体蛋白质、体水分和体灰分含量均显著减少,分别为12.99%、55.96%和3.25%,分别减少2.02%、8.02%和0.5%(P＜0.05).进一步证明了褪黑激素在动物营养分配中的作用,为褪黑激素在生产实践中的合理应用提供理论依据.     

光照对非生绒期内蒙古白绒山羊体成分的影响

从体成分的角度研究了光照对内蒙古白绒山羊营养分配的影响。结果表明,光照对体成分有较大影响,体脂肪随着光照时间的减少而增加,长光照、自然光照和短光照条件下绒山羊的体脂肪含量分别为23.6%、15.78%和14.16%,而体蛋白、体水分和体灰分含量则随着光照时间的减少而减少,长光照和自然光照组显著高于短光照组,长光照组和自然光照组差异不显著。证明了光照对绒山羊有调节营养分配的作用,为其在生产实践中的合理应用提供理论依据。     

光照和褪黑激素对内蒙古绒山羊氮分配的影响

从氮分配的角度研究了光照和褪黑激素对内蒙古白绒山羊营养分配的影响。结果表明:光照时间和埋植褪黑激素显著影响绒山羊体内氮物质分配,短光照或埋植褪黑激素显著提高绒山羊血液中的褪黑激素水平,并使其他相关激素如催乳素(PRL)、胰岛素(INS)、类胰岛素生长因子-I(IGF-I)、瘦素(LEP)的含量发生显著变化,结果使毛绒氮的沉积增加,体氮的沉积减少。短光照条件下毛绒氮和体氮的沉积分别为33.7%±0.64%和66.3%±0.64%;而长光照条件下则减少毛绒氮的分配量,增加体氮分配量,毛绒氮和体氮的沉积分别为23.6%±0.46%和76.4%±0.46%。短光照和褪黑激素之间有强烈的互作效应,短光照埋植褪黑激素组毛绒氮和体氮的分配比例分别为36.1%±0.79%和63.9%±0.79%。试验期绒山羊的产绒量平均增加(338.83±72)g,比普通绒山羊提高73.86%,新生羊绒的品质符合纺织工业标准的要求。     

光照对非生绒期内蒙古白绒山羊体成分的影响及其应用调控措施

从体成分的角度研究了光照对内蒙古白绒山羊营养分配的影响。结果表明,光照对体成分有较大影响,随着光照时间的减少,体内干物质的含量增加,体脂肪含量增加。长光照、自然光照和短光照条件下绒山羊的体脂肪含量占干物质的比例分别为41.43%±0.41%、44.43%±0.16%和53.90%±1.70%,而体蛋白、体水分和体灰分含量则随着光照时间的缩短而减少,绒山羊血液中与营养分配有关的激素也发生较大的变化。研究证明光照在绒山羊营养分配中的调节作用,为其在生产实践中的合理应用提供理论依据。     

光照和褪黑激素对非生绒期绒山羊激素分泌和绒毛生长的影响

为了研究光照和褪黑激素对绒山羊激素分泌和绒毛生长的影响。作者采用随机试验区组的方法,把36只绒山羊平均分成3组,分别进行长光照、短光照和自然光照处理,每组当中一半埋植褪黑素,分别检测血液激素水平和绒毛生长状况。结果表明,光照时间和埋植褪黑素显著影响绒山羊体内的激素分泌,长光照抑制褪黑素的分泌,短光照促进褪黑素的分泌,埋植褪黑素组的血浆褪黑素水平显著高于不埋植组。光照和褪黑素显著影响PRL、IGFI的分泌类型,并与绒山羊的绒毛生长有关,短光照或褪黑激素处理各组绒毛平均增加338.83 g;新生羊绒的长度、细度、强度等品质指标均符合纺织工业标准的要求。     

非产绒期控制光照和埋植褪黑激素对藏西北绒山羊增绒效果的影响

研究旨在探讨非生绒期控制光照和埋植褪黑激素对藏西北绒山羊增绒效果的影响,为藏西北绒山羊非产绒期选择一种有效的增绒技术。选择体重和产绒量基本一致、年龄2~3岁的藏西北绒山羊母羊60只,随机分为3组,试验为期1年。结果表明:控制光照组产绒量最高,显著高于对照组36.3%(P0.01),但与皮下埋植褪黑激素组无差异(P0.05);皮下埋植褪黑激素组羊绒长度极显著提高(P0.01),但与控制光照组无差异(P0.05);在羊绒细度指标上,各组间差异均不显著(P0.05)。表明皮下埋植褪黑激素是藏西北绒山羊生产上方便有效的增绒技术。     

光控和褪黑激素埋植对藏西北绒山羊生长和产绒性能的影响

藏西北绒山羊养殖作为西藏自治区牧民的主要经济来源,通过优化产业升级促进牧民的养殖效益至关重要。对藏西北绒山羊通过光控和褪黑激素埋植处理,进一步研究光照对于绒山羊体重生长、绒纤维长度以及机体血清褪黑激素浓度的影响,以期为光控增绒技术在西藏牧区示范推广提供数据支持和参考依据。试验结果表明:光控和埋植激素不能显著的影响机体的日增重变化(P0.05),但能够显著的影响藏西北绒山羊绒毛的纤维长度和生长速度(P0.05),另外光控和埋植激素能够提高绒山羊血清中的褪黑激素水平,从而影响机体的绒毛生长性能。综上在藏西北绒山羊养殖产业推广中通过光控和埋植激素能够有效的提高藏西北绒山羊的养殖经济效益。     

控制光照对内蒙古白绒山羊褪黑激素含量的影响

为研究非长绒期控制光照对内蒙古白绒山羊褪黑激素(MLT)含量的影响,随机选取12只年龄、产绒量和体重基本一致的内蒙古白绒山羊母羊,分为控制光照组(试验组)和对照组,每组各6只,采集血液样品进行褪黑激素含量测定,利用SAS 9.0软件进行显著性检验和相关性分析。结果表明,控制光照(试验组)使白绒山羊血液中的MLT含量在20:00、21:40、6:40时高于对照组,20:00、6:40时两组白绒山羊MLT含量差异显著(P0.05),试验组白绒山羊血液中MLT含量的高峰期维持时间显著长于对照组。10月,试验组与对照组MLT含量变化基本一致,差异均不显著(P0.05);对照组中10月白绒山羊血液中的MLT含量明显高于6月,但控制光照的白绒山羊血液中的MLT含量最高,说明控制光照可改变皮肤毛囊发育及绒毛生长周期,最终使内蒙古白绒山羊在非长绒期绒毛提前生长。     

埋植和饲喂褪黑激素对常年长绒型辽宁绒山羊生产性能的影响

试验旨在研究常年长绒型辽宁绒山羊慢速长绒期施用褪黑激素对机体生长及山羊绒生产的影响,并对褪黑激素埋植和饲喂2种施用方式进行比较。选用体况良好、体重相近、上一年产绒量基本一致的3周岁常年长绒型辽宁绒山羊母羊18只,随机分为3组,分别为对照组、3月和5月埋植组(2 mg/kg BW)和3—7月饲喂组(3 mg/d)。试验羊采用舍饲的饲养方式。试验从3月20日开始,7月20日结束,试验期共121 d。结果表明:施用褪黑激素显著提高了山羊绒长度和生长速率(P0.05),且埋植组显著高于饲喂组(P0.05),而对山羊绒细度没有影响(P0.05);试验羊结束体重和日增重各组间差异不显著(P0.05)。因此,常年长绒型辽宁绒山羊慢速长绒期施用褪黑激素可能是一种提高山羊绒生产的有效方法,且埋植比饲喂的效果更好。     

埋植外源褪黑激素对不同年龄内蒙古绒山羊产绒性能的影响

为研究非长绒期埋植外源褪黑激素对不同年龄内蒙古绒山羊产绒性能的影响,本试验选择2～6岁能繁母羊150只,每个年龄段根据产绒量和体重将母羊随机分为对照组和试验组,试验组于2014年4月30日和6月30日埋植2 mg/kg BW褪黑激素于耳部皮下。自埋植开始至试验结束(2015年4月底抓绒),逐月观察山羊绒生长情况,并于抓绒时采集绒样,分析埋植对山羊绒生长的影响。结果表明:与对照组相比,试验组所有年龄段山羊绒产量和绒长度均显著提高,绒细度显著降低(P<0.05),其中5岁埋植组山羊的产绒量提高幅度和细度下降幅度最大,分别达到28.75%、4.94%,6岁埋植组山羊绒长度增加幅度最大,为29.27%。综上,不同年龄内蒙古绒山羊埋植外源褪黑激素均有促进山羊绒生长和提高产量作用,但不同年龄绒山羊增产效果不一致,并且褪黑激素对于提高内蒙古绒山羊后期的生产力作用更大。     

光照和埋植褪黑激素对绒山羊相关激素分泌的影响

本试验旨在研究光照和褪黑激素对绒山羊内分泌的影响。本文采用随机区组试验的方法,把36只绒山羊平均分成3组,分别进行长光照(16L:8D)、自然光照(12.37hL)和短光照(8L:16D)处理,每种光照下一半埋植动物褪黑素,分别检测血液激素水平。结果表明:光照类型对绒山羊的激素分泌有显著的影响,长光照对催乳素(PRL)、类胰岛素促生长因子I(IGF-I)有促进作用,对褪黑素(MT)、胰岛素(INS)有抑制作用;短光照对催乳素(PRL)、IGF-I有抑制作用,对MT、INS有促进作用。埋植褪黑素后,在各种光照条件下对PRL、IGF-I均有抑制作用;INS在短光照+MT组降低,在自然光照+MT和长光照+MT组升高。这些都表明,几种激素在一天之内随着时间(光照)的变化而呈现不同程度的波动变化。     

Lactation Biology Symposium: effects of photoperiod on mammary gland development and lactation

Photoperiod, or the daily sequence of light and dark, has dramatic effects on many physiological systems across animal species. Light patterns alter melatonin secretion profiles and, subsequently, the release profiles and circulating concentrations of several hormones that influence a variety of physiological responses. Although the impact of photoperiod on reproductive processes is perhaps the most common example, it is often the seasonal aspects of ovulation and anestrus that are considered. However, in cattle, the final phase of reproduction, that is, lactation, is significantly influenced by photoperiod. In contrast to short days (SDPP; 8 h light:16 h dark), exposure to long days (LDPP) of 16 to 18 h of light and 6 to 8 h of darkness increases milk yield 2 to 3 kg/d, regardless of the stage of lactation. There is evidence that this LDPP effect is due to increased circulating IGF-I, independent of any effect on GH concentrations. Cows that are housed under SDPP during the dry period have increased mammary growth and produce 3 to 4 kg/d more milk in the subsequent lactation compared with cows on LDPP when dry. While cows are on SDPP, circulating prolactin (PRL) diminishes but expression of PRL receptor increases in mammary, liver, and immune cells. Moreover, PRL signaling pathways within those tissues are affected by photoperiod. Further, replacement of PRL to cows on SDPP partially reverses the effects of SDPP on production in the next lactation. Thus, effects on dry cows are mediated through a PRL-dependent pathway. Before maturity, LDPP improve mammary parenchymal accumulation and lean body growth, which lead to greater yields in the first lactation. The accumulated evidence supports the concept that photoperiod manipulation can be harnessed to improve the efficiency of production across the life cycle of the dairy cow.     

Effect of photoperiod on milk yield and quality, and reproduction in dairy goats

The objective of this study was to examine the effect of long day photoperiod (LDPP) on milk production and reproduction in milk goats. A total of 79 goats were randomly assigned to three treatment groups blocked by day of kidding. Group 1 (Gr1, n = 26) was subjected to natural photoperiod from January 6 to December 5. Group 2 (Gr2, n = 24) was subjected to LDPP (20 h light, 4 h dark) from June 22 to December 5. Group 3 (Gr3, n = 29) was subjected to LDPP from January 6 to December 6. Weekly milk weights and samples were collected for fat, protein and somatic cell count (SCC) determinations. Blood serum was harvested for progesterone (P4) determination. Results indicated a significant effect (p < 0.001) between treatments for body weight changes, feed intake and milk yield. Both light treated groups had a significantly higher (p < 0.001) average daily milk output for the entire lactation period than the control group (G1, 2.193 kg/day; G2, 2.517 kg/day; G3, 2.305 kg/day). Milk fat for the overall lactation was significantly higher in Gr3 (+ 0.19 g/100 ml) than for Gr2 (+ 0.06 g/100 ml) when compared to the control group (x g/100 ml) under natural photoperiod. Somatic cell counts throughout lactation were significantly (p < 0.001) lower for Gr2 (1.70 million/ml) and higher for Gr3 (2.03 million/ml), with the control group (Gr1) having an intermediate level (1.96 million/ml). Progesterone levels between June 9 and August 30 indicated that 27%, 48% and 63% of the animals had P4 levels in excess of 1.0 ng/ml serum for Gr1, Gr2 and Gr3, respectively. Pregnancy diagnosis by ultrasound in December revealed that a high number of does in the light treated groups (10 of 37) were pseudo-pregnant when compared with the control group (1 of 21). Although light appeared to be effective in increasing milk production, further investigations are needed to evaluate the effect of LDPP on pseudo-pregnancy in dairy goats.     

Effects of photoperiod on the secretion of growth hormone in female goats

The aim of the present study was to clarify the effect of photoperiod on the secretion of growth hormone (GH) in goats. Adult female goats were kept at 20°C with an 8‐h or 16‐h photoperiod, and secretory patterns of GH for 4 h (12.00 to 16.00 hours) were compared. In addition, the goats were kept under a 16‐h photoperiod and orally administered saline (controls) or melatonin, and the effects of melatonin on the secretion of GH were examined. GH was secreted in a pulsatile manner. There were no significant differences in pulse frequency between the 8‐ and 16‐h photoperiods; however, GH pulse amplitude tended to be greater in the group with the 16‐h photoperiod (P = 0.1), and mean GH concentrations were significantly greater in the 16‐h photoperiod (P < 0.05). The GH‐releasing response to GH‐releasing hormone (GHRH) was also significantly greater for the 16‐h photoperiod (P < 0.05). There were no significant differences in GH pulse frequency between the saline‐ and melatonin‐treated groups. However, GH pulse amplitude and mean GH concentrations were significantly greater in the saline‐treated group (P < 0.05). The present results show that a long photoperiod enhances the secretion of GH, and melatonin modifies GH secretion in female goats.     

不同光周期和褪黑激素对绒山羊生产性能影响

本研究在山羊非长绒季节（２～６月），在人工控制环境条件下，通过改变光周期和褪黑激素处理，探讨对绒山羊生产性能的影响。研究结果表明：每日８小时光照，不论褪黑激素处理与否，山羊都能长绒；每日１６小时光照，经褪黑激素处理，可诱使山羊长绒。随产绒量增加，绒纤维长度和细度显著变化。光周期和褪黑激素是影响山羊绒生长的主要因素。     

Exposure to blue LED light before the onset of darkness under a long‐day photoperiod alters melatonin secretion,feeding behaviour and growth in female dairy calves

The effect of blue LED on melatonin secretion, feeding behaviour and growth was addressed in Holstein female dairy calves. In Exp.1, six animals (8 weeks old, 97 ± 4.1 kg BW) were exposed to yellow or blue LED for 2 hr before darkness over 7 days under a long‐day photoperiod (LDPP). In Exp. 2, six animals (8 weeks old, 88.5 ± 4.8 kg BW) were exposed to blue light from a white LED all daytime or a yellow LED for 2 hr before the darkness of LDPP (blue light cut) over 3 weeks. In Exp. 1, blue light mildly suppressed melatonin secretion during the 2‐hr treatment but did not affect the timing of the nightly melatonin rise. However, the rise in nighty melatonin levels was higher with yellow than blue LED. In Exp. 2, white LED completely suppressed melatonin secretion during the 2‐hr treatment, but plasma melatonin concentrations were similar during the darkness. Grass hay intake, rumination time, frequency of water intake and body weight gain were higher in animals exposed to the yellow rather than the white LED. Overall results indicate that exposure to blue light from white LEDs under an LDPP suppresses melatonin secretion and might negatively impact the development of female dairy calves.     

Growth, carcass composition and plasma melatonin in postpubertal beef heifers fed melatonin

Two experiments were conducted to determine if feeding melatonin alters plasma concentrations of melatonin, growth and carcass composition of postpubertal beef heifers exposed to 16 h light (L):8 h dark (D). In Exp. 1, 16 heifers were blocked by initial body weight (318 +/- 5.6 kg). Four heifers were killed before starting the melatonin treatment to obtain initial carcass composition. Six heifers received vehicle (95% ethanol) and six were fed melatonin (4 mg/100 kg body weight) daily for 58 d at 1330 to coincide with the middle of the 16-h light period. On d 59 heifers were slaughtered. Melatonin feeding increased the percentage of fat in rib (P less than .05) and longissimus muscle (LD; P less than .10) and carcass fat accretion 28% (P less than .09) but reduced the percentage of protein 8% in rib (P less than .05) and carcass protein accretion 30% (P less than .09). Other measures in the carcass and body weight gain were not affected (P greater than .10) by feeding melatonin. Plasma concentrations of melatonin increased (P less than .01) from 10 to 140 pg/ml within 30 min of feeding melatonin. In Exp. 2, 24 heifers were blocked by initial body weight (348 +/- 13.7 kg). Eight heifers were killed initially, eight received vehicle and eight were fed melatonin for 63 d as described in Exp. 1. Melatonin did not influence (P greater than .10) body weight gain or any measure in the carcass; however, these heifers were fatter (40.1%) than those in Exp. 1 (30.9%) at the beginning of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of photoperiod on circadian clock genes in skin contribute to the regulation of hair follicle cycling of Inner Mongolia white cashmere goats

This study investigated how the effects of photoperiod on circadian clock genes in the skin contribute to the regulation of hair follicle cycling of Inner Mongolia white cashmere goats. Twenty‐four female (non‐pregnant) Inner Mongolia white cashmere goats aged 1 ? 1.5 years old with similar live weights (mean, 20.36 ± 2.63 kg) were randomly allocated into two groups: a natural daily photoperiod group (NDPP group:10 ? 16 hr Light, n = 12) and a short daily photoperiod group (SDPP group: 7 hr Light:17 hr Dark, n = 12). All goats were housed in individual pens from May 15 to October 15, 2015 and were fed the same diets. We detected the mRNA expression of brain and muscle arnt‐like protein‐1 (Bmal1), circadian locomotor output control kaput (Clock), cryptochrome‐1 (Cry1), period homolog‐1 (Per1) and Rev‐erbα genes in the goat skin. ANOVA revealed a significant 24 hr (10:00 hr, 14:00 hr, 18:00 hr, 22:00 hr, 02:00 hr, 06:00 hr, 10:00 hr) variation between the SDPP and NDPP groups for three months (July, September, and October). In summary, the current results confirm that an intrinsic oscillating molecular clock exists in goat skin, and that the clock is important for potential timing mechanisms at the anagen phase of hair follicles, which would contribute to the regulation mechanisms of hair follicle cell proliferation.     

Response of body weight and clearance and secretion rates of growth hormone to photoperiod in Holstein heifers

Effects of photoperiod on growth, eating patterns and clearance rate, secretion rate and half-life of growth hormone in serum were assessed in Holstein heifers. Sixty-four prepubertal heifers (avg body wt 102 kg) were blocked by weight into four groups of 16. Within block, each animal was randomly assigned to one of four photoperiod treatments: 16 h of cool-white fluorescent light:8 h dark (CW-16L:8D), CW-8L:16D, CW-6L:8D:2L:8D or 16 h of VitaLite fluorescent light:8D (V-16L:8D). Animals were fed ad libitum a complete mixed diet formulated for heifers to gain approximately .9 kg/d. Average daily body weight gains were .93, .96, .98 and 1.0 kg/d during 112 d of exposure to CW-8L:16D, CW-6L:8D:2L:8D, CW-16L:8D and V-16L:8D, respectively. Heifers exposed to V16L:8D and CW-16L:8D gained more weight (112 and 110 kg; P less than .05 and P less than .08, respectively) than heifers exposed to CW-8L:16D (104 kg). Body weight gain was not different (P greater than .10) between heifers exposed to CW-6L:8D:2L:8D (108 kg) or CW-8L:16D, or between heifers exposed to CW-16L:8D or V-16L:8D. Total number of eating events in 30 h and percentage of total events in the lighted period were 549 and 96% and 523 and 50% in heifers exposed to CW-16L:8D and CW-8L:16D, respectively. Clearance rates (620 vs 636 ml/min), secretion rates (3.0 vs 3.8 micrograms/min) and half lives (17.2 vs 17.9 min) of growth hormone in serum were similar in heifers exposed to CW-16L:8D and CW-8L:16D.(ABSTRACT TRUNCATED AT 250 WORDS)