【作者】 张铁涛；

【导师】 高秀华；

【作者基本信息】 中国农业科学院 ， 动物营养与饲料科学， 2012， 博士

【摘要】 水貂是珍贵的毛皮动物，属于食肉目鼬科鼬属，对饲粮中蛋白质数量和质量要求很高。本论文主要研究了干粉型饲粮蛋白质和赖氨酸、蛋氨酸对生长期水貂生产性能、消化代谢规律及肠道结构的影响。通过饲养试验，消化代谢试验、屠宰试验、组织学试验、分子生物学试验、结合氨基酸色谱分析技术，系统研究生长期(分为育成期和冬毛期)水貂在不同日龄对饲粮蛋白质、氨基酸的消化、吸收和代谢机制。确定水貂蛋白质和氨基酸的营养需要量，为干粉型饲料的应用推广奠定理论基础，为实际养殖生产提供理论指导。本研究包括两个试验部分：试验一饲粮蛋白质水平对生长期水貂生产性能，消化代谢和肠道结构的影响选择健康50日龄断奶水貂120只，公母各半，随机分成6组，每组10只公貂平均体重为778.23±119.05g，每组10只母貂平均体重为577.46±73.28g，各组间的体重差异不显著(P>0.05)，每组设20个重复，每个重复1只，水貂均为单笼饲养。六组水貂分别饲喂饲粮的蛋白质水平为28%(Ⅰ组)、30%(Ⅱ组)、32%(Ⅲ组)、34%(Ⅳ组)、36%(Ⅴ组)、38%(Ⅵ组)的饲粮。结果表明：1.水貂在育成期50~65日龄，65~80日龄，80~95日龄，95~110日龄，适宜的蛋白质摄入量分别为30~33g/d，28~35g/d，30~32g/d，29~40g/d。2.水貂在冬毛期内，公貂在前期、中期和后期适宜的蛋白质摄入量分别为42~48g/d，36~42g/d，41~47g/d；母貂在前期、中期和后期适宜的蛋白质摄入量分别为28~30g/d，25~27g/d，30~32g/d，水貂可获得适宜的毛皮质量。3.水貂在不同时期对试验饲粮的营养物质消化率存在显著性差异(P<0.05)；整体上看，育成期和冬毛期水貂分别对34%~36%、32%~34%蛋白质饲粮的蛋白质消化率和氮沉积比较好；饲粮中蛋白质能够提高水貂的脂肪消化率(P<0.05)。4.育成期水貂饲粮蛋白质水平为28%时，水貂体增重最小(P<0.05)；蛋白质水平为34%时，水貂体增重最大(P<0.05)；蛋白质水平为36%时，血清总氨基酸、总蛋白及谷草转氨酶活性高于其他各组(P<0.01)。5.饲粮蛋白质水平为34%~36%时，水貂的空肠绒毛、隐窝深度、肠粘膜厚度等指标高于其它试验组(P<0.01)，饲粮中的蛋白质水平能够调节水貂的肠道形态结构。6.黑素皮质素受体基因(MC1R)转录水平的表达量在各组水貂间差异极显著(P<0.01)，32%蛋白质组水貂的表达量最高，38%蛋白质组水貂的表达量最低，说明饲粮蛋白质对水貂的毛皮颜色和成熟时间具有影响。试验二赖氨酸、蛋氨酸水平对生长期水貂生产性能，消化代谢和肠道结构的影响选择健康的60日龄水貂200只，公母各半，随机分成10组，每组10只公貂平均体重为806.39±107.13g，每组10只母貂平均体重为586.74±90.15g。采用2因素3水平的试验设计，在32%蛋白质水平饲粮基础上分别添加0、0.3%、0.6%的赖氨酸和蛋氨酸，0添加的饲粮组为基础组，34%蛋白质饲粮组作为对照组。结果表明：1.育成期水貂饲粮赖氨酸水平为1.64%~1.94%、蛋氨酸水平为0.80%~1.10%时，基础组水貂补充氨基酸后的生长性能优于34%饲粮蛋白质组水貂；冬毛期公貂的饲粮赖氨酸水平为1.39%~1.69%、蛋氨酸水平为1.10%~1.40%时，水貂能够维持较好的生长性能；冬毛期母貂的饲粮赖氨酸水平为1.59%~1.89%、蛋氨酸水平为0.80%~1.10%时，水貂处于较为理想的生长状态。2.饲粮中添加赖、蛋氨酸能够对水貂的皮毛质量产生影响。饲粮中蛋氨酸含量达到1.10%，胱氨酸含量为0.35%时，水貂的皮张面积最大。冬毛期水貂饲粮中适宜的蛋氨酸含量为0.85%~1.10%。3.生长期公貂的饲粮赖氨基酸水平为1.64%~1.94%、蛋氨酸为1.10%~1.40%；生长期母貂的饲粮赖氨基酸水平为1.59%~1.75%，蛋氨酸为0.8%~1.10%，基础组饲粮添加0.3%~0.6%赖氨酸后，生长期水貂对营养物质的消化率能达到34%饲粮蛋白质组的消化率(P>0.05)。4.育成期饲粮添加0.3%Lys、0.6%Met的饲粮氨基酸相对平衡，公貂血清尿素氮极显著低于基础组水貂（P<0.01）；冬毛期公貂饲粮添加0.6%Lys、0.3%Met；生长期母貂饲粮添加0.3%Lys、0.3%~0.6%Met水貂的蛋白质和氨基酸代谢旺盛，血清总氨基酸(TAA)维持较高水平。5.饲粮中添加0.3%蛋氨酸和0.6%蛋氨酸，能够提高水貂胃蛋白酶活性；饲粮中添加0.3%蛋氨酸或饲粮添加0.3%%~0.6%赖氨酸、0.3%蛋氨酸时，水貂的空肠吸收面积最大；饲粮中添加0.3%赖氨酸和0.3%蛋氨酸，提高水貂十二指肠胰蛋白酶的活性；饲粮中添加0.6%Met或者饲喂高水平的蛋白质饲粮，能够提高水貂空肠和回肠中胰淀粉酶和胰脂肪酶的活性。综上所述，处于不同生长时期的水貂对饲粮中蛋白质和氨基酸的需要与代谢规律不同，提供适宜的蛋白质和氨基酸，水貂能获得最佳的生产性能。合理配制饲粮，不但能够减少养殖过程中氮的排放量，而且降低饲养成本，获得最佳的经济效益。更多还原

【Abstract】 As a kind of precious fur animals, mink (Carnivora mustelidae mustelia) has high daily proteinrequirements. The current study was conducted to investigate the effects of proteins, lysine andmethionine in dry-powder diet on production performance of growing mink. A combined strategycomprising of feeding trials, digestion and metabolism experiments, slaughter experiment, histology,molecular biology and chromatography of amino acid were employed to study the mechanisms ofproteins and amino acids digestion, absorption and metabolism in minks at different day-age. Thenutritional requirements of proteins and amino acids in mink were estimated to provide the data fordry-powder feed application in animal husbandry. This study was divided into two parts.Part1: Effects of protein levels on production performance, regularation of metabolism andintestinal characteristics in growing minksOne hundred and twenty healthy weaned50-day minks were randomly assigned into six treatments(the average body weight of each treatment had no significant difference, P>0.05), half male (averagebody weight of0.778±0.119kg) and half female (average body weight of0.577±0.073kg). Everygroup had20replications, with one mink in each replication. Each mink was fed in an individual pen.Minks from six groups were supplemented with28%(group Ⅰ),30%(group Ⅱ),32%(group Ⅲ),34%(group Ⅳ),36%(group Ⅴ) and38%(group Ⅵ) proteins, respectively. The main results were as follow:1The optimal protein intakes of minks at50-65day,65-68day,80-95day and95-110day were30-33g/d,28-35g/d,30-32g/d and29-40g/d, respectively.2The optimal protein intakes of male minks at early, middle and late winter hair period were42-48g/d,36-42g/d and41-47g/d. However, taking25-27g/d or30-32g/d were beneficial for those femaleminks at middle or late winter hair period to produce high-quality fur.3The digestibility of main nutrient had the sigenificantly difference at various physical stage in themink by the experiment of metabolism and digestibility(P<0.05). The mink fed with34%~36%dietary protein levelvs had higher digestibility of protein and nitrogen deposition at the grwoing period.The mink fed with32%~34%dietary protein levelvs had the same regularity at the fur bearingperiod(P<0.05). Dietary protein could enhance the digestibility of crude fat in the growth period(P<0.05).4The average body weight gain of growing female minks in group Ⅰ was minimum, whilemaximum in group Ⅳ. The activity of aspartate aminotransferase, total amino acid and total proteinconcentrations in serum of growing female minks in group Ⅴ were higher than those in other groups.5The villus height, crypt depth and mucosa thickness of jejunum in group Ⅳ and group Ⅴ werehigher than those of other groups, indicating that protein concentrations could adjust the morphology ofintestinal tract in mink.6The expression level of gene MC1R were significantly differently (P<0.01) among groups.Compared with group Ⅰ, MC1R expression level was highest in group Ⅲ and lowest in group Ⅵ, suggesting that protein concentrations contributed to color and maturation of fur.Part2: Effects of methionine levels on production performance, regularation of metabolism andintestinal characteristics in growing minksTwo hundred60-day minks were randomly assigned into ten treatments (the mean body weight ofeach treatment had no significant difference, P>0.05), half male and half female. Every group had20minks, half male and half female. The two factors and three levels experimental design was carried outto add0,0.3%or0.6%lysine/methionine to32%protein group, and the34%protein group was used aspositive control. The main results were as follow:1The concentrations of lysine and sulfur amino acid were1.64%-1.94%and0.91%-1.21%in dietof growing mink. Growing performance of minks in treatment group supplemented with amino acid wasbetter than those in34%protein group. The optimum concentrations of lysine and sulfur amino acidwere1.39%-1.69%and1.24%-1.54%for production performance of male minks at winter hair period,while1.59%-1.89%and0.94%-1.24%in female minks.2Lysine and methionine had effects on fur quality of minks. The optimum concentrations of lysineand sulfur amino acid were1.29%and0.94%. The fur area was biggest, when concentrations ofmethionine and cystine were1.2%and0.35%. The optimum concentration of sulfur amino acid was1.24%-1.54%and lysine/methionine was1:0.83-1.28.3The concentrations of lysine and methionine were1.64%-1.94%and1.39%-1.69%in diet ofgrowing male minks, while those were1.59%-1.75%and1.24%-1.61%in female minks. The digestionefficiency in basal diet supplemented with amino acid was comparative to that of34%protein group.4The concentrations of serum urea nitrogen in growing male minks supplemented with0.3%Lysand0.6%Met were significantly lower (P<0.01) than that of basal diet group. The growing femaleminks supplemented with0.3%Lys and0.6%Met showed good protein and amino acid metabolism,and high serum TAA.5The pepsin activity was improved by0.3%-0.6%Met.The absorption area of jejunum was highest in minks supplemented with0.3%Met or0.3%-0.6%Lys and0.3%Met. Addition of0.3%Lys and0.3%Met could enhance catalytic activity of duodenumtrypsase of minks. Those diets supplemented with0.6%Met or high level proteins could improve theactivities of amylopsin and pancreatic lipase.In summary, the requirements and metabolism of protein and amino acids vary in minks ofdifferent growing periods. Diets supplemented with moderate proteins and amino acids are capable toimprove production performance of minks. It is desirable to use properly formulated rations forreducing the nitrogen emission and cost in mink feeding.更多还原