【作者】 王松；

【导师】 高腾云；

【作者基本信息】 河南农业大学 ， 动物遗传育种与繁殖， 2007， 硕士

【摘要】 以豫北黄河故道区当地小尾寒羊为对照,用观察、实验和综合分析的方法,研究了Dorsetdown绵羊对豫北黄河故道区的适应性,目的在于为这一优良肉用品种的推广应用提供依据。试验一:Dorset down绵羊对豫北黄河故道区夏季炎热气候的适应性。在豫北黄河故道区6月和8月上旬分别测定羊舍温热环境状况、羊生理指标和血液生化指标,结果表明:（1）6月和8月Dorset down均出现了热应激现象,15:00时和8:00时相比,呼吸率、直肠温度和毛丛温度均显著增高（P＜0.01）,心率有增高,但差异不显著。（2）直肠温度衡量热应激程度较为灵敏。Dorset down直肠温度上升的临界点为温湿指数（THI）80-81左右。（3）8月Dorset down和小尾寒羊在相同时间点各项指标均无显著差异。（4）Dorset down公羊各项常规生理指标全面低于母羊,耐热性有强于母羊的趋势,但差异不显著。（5）逐步回归分析表明,在新乡夏季高温高湿条件下,湿度对各项生理指标的影响高于温度的影响。（6）6月Dorset down血清皮质醇水平高于8月41.33%,8月Dorset down皮质醇含量水平高于小尾寒羊37.48%。血清中K⁺、Na⁺、Cl^-、Ca²⁺含量差别不显著,8月小尾寒羊血清Ca⁺含量显著低于Dorset down。试验二:Dorset down绵羊在豫北黄河故道区的牧食行为。通过对舍饲生产系统和放牧生产系统饲喂方式和生长发育状况进行比较,探讨Dorset down在豫北黄河故道区适宜的饲养方式。结果表明:（1）Dorset down平均采食速度为38.8±7.2次/分,略低于小尾寒羊;单口采食量（DM）为97.9mg/口;日均采食量为1.19kg/d,略低于小尾寒羊。一天之内其采食速度变化较大,觅食速度明显受放牧地状况影响。（2）Dorset down对牧草选择性大于小尾寒羊,不同地区牧草状况对其影响较大。（3）Dorset down放牧下平均每食团咀嚼口数49.0±8.8次/min,每食团咀嚼时间35.3±7.1s,每分钟反刍食团数1.35个/min,与小尾寒羊没有明显差别。试验三:Dorset down绵羊在舍饲与放牧生产系统下的性能表现。通过对舍饲和放牧生产系统下Dorset down的生长发育、发病率情况的评定和调查,探讨Dorset down在豫北黄河故道区适宜的生产系统。结果表明:（1）Dorset down耐粗饲性差,舍饲生产系统的饲喂效果不如放牧生产系统。（2）放牧生产系统下的Dorset down夏季发病率和死亡率明显高于舍饲生产系统和同生产系统的小尾寒羊。（3）Dorset down在舍饲生产系统下其后代生长发育状况出现了一定的退化现象,在放牧生产系统下未出现退化现象。试验四:绵羊血液褪黑激素和生殖激素在不同季节的变化规律。分别在春夏秋冬四个季节,选择处在间情期的空怀Dorset down羊和小尾寒羊母羊,测定血液中褪黑激素和生殖激素的昼夜水平。结果表明:（1）Dorset down羊不同月份FSH血浆浓度均低于小尾寒羊,但差异不显著。两者变化规律一致,11月最高,6月最低。Dorset down羊LH血浆浓度在4、6月时和小尾寒羊基本相同,在9、11月显著高于小尾寒羊（P＜0.05）,变化规律有所不同。（2）Dorset down羊E₂水平在4月份显著高于小尾寒羊（P＜0.01）,6、9月相差很小,11月低于小尾寒羊（31.1%）,差异不显著。Dorset down羊血浆P₄浓度除了4月略高于小尾寒羊,6、9、11月均显著低于小尾寒羊。（3）褪黑激素分泌水平存在着明显的昼夜和季节性交化,春夏明显高于秋冬。Dorset down羊MLT血浆浓度4月到6月升高的幅度明显大于小尾寒羊,6月到9月下降的幅度亦大于小尾寒羊。（4）MLT通过调节下丘脑和垂体对E2负反馈作用的敏感性,经MLT-E2-FSH这一途径对绵羊发情产生影响。综合分析表明:,在豫北黄河故道区,Dorset down可以适应当地夏季炎热气候,气候条件的差异和变化并没有明显影响Dorset down羊的基本特性和总体生产水平,“总适应能力”评定结果达到良好。在豫北黄河故道区,放牧生产系统更能发挥其生产潜力。更多还原

【Abstract】 This paper studied the adaptation of Dorset down,which introducted from New Zealand, rearing at the area of old Yellow River course in northern Henan province by the means of observation,essay and analysis,The goal lies in for this breed provides the basis for extension.Experiment 1:The adaptability of Dorset down sheep on local hot weather condition. Climatic condition of sheep shed,physiological index and serum biochemical traits of Dorset down sheep were measured on June and August.The results shows:（1）Dorset down sheep was in heat stress both on June and August.The results of respiratory rate,rectal temperature and flocci temperature at 15:00 are extreme significant higher than 8:00.（2）The index of rectal temperature contribute most to the measurement of heat stress and the critical point of rectal temperature raising of Dorset down sheep was that THI was about 80-81.（3）There is no significant difference between the results of Dorset down sheep and Small-tail Han sheep on same period.（4）Every physiological indexes of rams about heat stress were lower than ewes,there was no significant difference.（5） According to the stepwise regression analysis,the humidity had a great influence on physiological index than that of high temperature in Xinxiang under the high temperature humidity summer condition.Serum COR concentration of Dorset down on June was 41.33%higher than August and serum COR level of Dorset down was 37.48%higher than Small-tail Han sheep.The concentration different of K⁺、Na⁺、Cl^、Ca²⁺on same period all were no significandy.Experiment 2:The grazing behavior of Dorset down sheep on local pasture.By comparing the feeding mode and growth and development state in different management mode,the eligible management mode of Dorset down sheep was discussed.The results shows:（1）Average intake rate of Dorset down sheep was 38.8±7.2bite/min,which was little lower than Small-tail Han sheep’s; average intake（DM）was 97.9 mg/bite;average intake each day was 1.19kg/d,The change of intake rate was wider than Small-tail han sheep on whole day,foraging rate was obviously effected by various pasture condition.（2）The selectivity of Dorset down on forage grass was higher than Small-tail Han sheep,which was highly effect by pasture state.（3）When Dorset down was in grazing mode,average chewing bites each cud was 49.0±8.8 bite/min,average chewing times each cud was 35.3±7.1s,average cud numbers each minute was 1.35,there was no significant difference between Dorset down and Small-tail Han sheep. development,disease incidence of Dorset down sheep in different produce system were investigated, which to study the suitable produce system of Dorset down sheep at the area of old Yellow River course in northern Henan province.The results shows:（1）Growth and development of Dorset down sheep in grazing produce system was better than in confine produce system.（2）Morbidity of Dorset down sheep in grazing produce system were higher than that in confine produce system and Small-tail Han sheep in grazing produce system.6)Partial degeneration of Dorset down sheep offspring was occurred in confine produce system but not occurred in grazing produce system.Experiment 4:The change of melatonin and reproductive hormone levels of sheep in different seasons.The 8 Dorset down sheep and 8 Small-tall Han sheep on diestrus were chose and the levels of blood melatonin and reproductive hormones were tested on April,June,September and November respectively,which to study the secrete regularity of hormones on diestrus during the whole year.The results show that:（1）The serum FSH levels of Dorset down sheep are always lower than Small-tall Han sheep on various months,but the difference was not significant.The highest level occurred on November and the lowest occurred on April.The serum LH levels of Dorset down sheep were similar with Small-tail Han sheep on April on June and significant higher on September and November.（2）The serum E₂ levels of Dorset down sheep were significant higher than Small-tail Han sheep on April,the different on other months were small and not significant. The serum P₄ level of Dorset down was little higher than Small-tall sheep,on the other months Dorset down sheep were significant lower than Small -tail Hart sheep.（3）The apparent circadian and seasonal rhythms of melatonin secretion were existed.The secretion levels on spring and summer were significant higher than fall and winter.The raising scope of Dorset down sheep melatonin level from April to June very bigger than Small-tail Hart sheep,the descend scope from September to November was also bigger than Small-tail Hansheep.（4）Melatonin can influence the sensitivity of hypothalamus and hypophysis to E₂,which can influence the estrus of sheep through MLT-E2-FSH path.The generalized analysis indicated that,Dorset down sheep adapt to the hot weather of the old Yellow river course in northern Henan province.The change of ecological conditions doesn’t influence the basic character and overall production level of Dorset down sheep obviously.The comprehensive evaluation "total adaptiveness" achieves good.In the area of old Yellow River course in northern Henan province,Dorset down sheep could display its productive potential in grazing production system.更多还原