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1.
The present experiments were performed to study the effects of a single high intravenous dose of Liquoid (10 mg/kg body weight) upon platelets, coagulation activities and hematocrit in blue foxes, and their correlation with the survival time. Both “short-living” (< 9 h) and “long-living” (24 h or more) blue foxes showed a marked consumption of coagulation factors, initial fall in fibrinogen, positive ethanol gel test and a gradual decrease in platelet counts. In addition “short-living” animals developed a marked rise in hematocrit, reflecting a considerable increase in vascular permeability. We conclude that activation of plasma proteases has as one of its effects increased permeability in microvasculatory vessels and that this may play a central role for the course and outcome of Liquoid-induced disseminated intravascular coagulation. 相似文献
2.
The objective of the present study was to examine the feasibility of the production of autologous porcine somatic cell nuclear transfer (SCNT) blastocysts using oocytes and donor cells from slaughtered ovaries. Therefore, we attempted to optimize autologous SCNT by examining the effects of electrical fusion conditions and donor cell type on cell fusion and the development of SCNT embryos. Four types of donor cells were used: 1) denuded cumulus cells (DCCs) collected from in vitro-matured (IVM) oocytes; 2) cumulus cells collected from oocytes after 22 h of IVM and cultured for 18 h (CCCs); 3) follicular cells obtained from follicular contents and cultured for 40 h (CFCs); and 4) adult skin fibroblasts. The DCCs showed a significantly (p < 0.01) lower rate of fusion than the CCCs when two pulses of 170 V/mm DC were applied for 50 µsec (19 ± 2% vs. 77 ± 3%). The rate of DCC fusion with oocytes was increased by the application of two DC pulses of 190 V/mm for 30 µsec, although this was still lower than the rate of fusion in the CCCs (33 ± 1% vs. 80 ± 2%). The rates of cleavage (57 ± 5%) and blastocyst formation (1 ± 1%) in the DCC-derived embryos did not differ from those (55 ± 6% and 3 ± 1%, respectively) in the CCC-derived SCNT embryos. Autologous SCNT embryos derived from CFCs (5 ± 2%) showed higher levels of blastocyst formation (p < 0.01) than CCC-derived autologous SCNT embryos (1 ± 0%). In conclusion, the results of the present study show that culturing cumulus and follicular cells before SCNT enhances cell fusion with oocytes and that CFCs are superior to CCCs in the production of higher numbers of autologous SCNT blastocysts. 相似文献
3.
干旱适应能力不仅包括干旱胁迫期间的抗旱能力,也包括水分胁迫解除之后的恢复能力。以8个高粱品种为材料,采用盆栽称重控水法对高粱幼苗进行干旱及复水处理,通过测定生物量、相对含水量、水势、渗透势、光合参数等生理指标的变化分析不同品种高粱抗旱能力和旱后复水恢复能力的大小及其与干旱适应性的关系,并筛选出能有效指示干旱适应能力的生理指标。结果显示,干旱胁迫条件下,“辽杂21”生物量与对照相比无显著差异,抗旱能力较强;“甘蔗籽”和“Moench.cv.Gadambalia”高粱生物量分别下降38%、34%,抗旱能力较差。各品种高粱的相对含水量、水势、渗透势、叶绿素含量、净光合速率、蒸腾速率、气孔导度等均有所下降,复水后,这些生理指标恢复到对照水平,各品种开始恢复生长。由各生理指标与抗旱能力、旱后复水恢复能力和干旱适应能力之间的相关分析结果表明,高粱的干旱适应性与复水恢复性呈显著正相关(r=0.85),与抗旱性的相关系数是0.46,复水恢复能力在高粱干旱适应性中起着更重要的作用。高粱的抗旱性和旱后复水恢复性具有不同的生理基础,在干旱胁迫期间维持较高的净光合速率、较低的蒸腾速率有助于提高抗旱性,维持较高叶片相对含水量有助于提高旱后复水的恢复能力,叶片相对含水量、净光合速率可以作为筛选高粱干旱适应性的生理指标。 相似文献
4.
Transfer of porcine embryos after 3 days of in vitro culture 总被引：1，自引：0，他引：1
Two experiments were conducted to determine the viability of porcine embryos transferred after long-term in vitro culture. In Exp. 1, four-cell embryos were kept in culture for 120 h. Embryos that were exposed to fresh culture medium every 12 h survived better than embryos kept in the same medium throughout the culture period. In Exp. 2, four- and eight-cell embryos were cultured in vitro for 72 h before transfer to estrus-induced recipient gilts. Each gilt received, on average, 19 embryos. If recipients were synchronous with donors 3/32 (9%) recipients remained pregnant with an average of 4.0 +/- .6 viable young. If the sexual cycle of the recipients was 24 h behind that of the donors the pregnancy rate was 18/34 (53%) with 4.4 +/- .5 viable young. Average embryo survival rate for the two groups was 1.8 and 12.5%, respectively. A 24-hourly medium replacement during the in vitro culture period had no significant effect on transfer results. When transferring freshly collected blastocysts, pregnancy rate, number of viable young and survival rate of embryos were 6/10 (60%), 7.8 +/- 1.4, and 23.9% for synchronous recipients and 7/10 (70%), 9.3 +/- 1.8, and 32.9% for asynchronous recipients, respectively. Recipients with very high plasma progesterone levels or numerous follicular cysts at the time of transfer were less likely to remain pregnant than others. 相似文献
5.
This study examined effects on the developmental competence of pig oocytes after somatic cell nuclear transfer (SCNT) or parthenogenetic activation (PA) of : 1) co-culturing of oocytes with follicular shell pieces (FSP) during in vitro maturation (IVM); 2) different durations of maturation; and 3) defined maturation medium supplemented with polyvinyl alcohol (PVA; control), pig follicular fluid (pFF), cysteamine (CYS), or β-mercaptoethanol (β-ME). The proportion of metaphase II oocytes was increased (p < 0.05) by co-culturing with FSP compared to control oocytes (98% vs. 94%). However, blastocyst formation after SCNT was not improved by FSP coculture (9% vs. 12%). Nuclear maturation of oocytes matured for 39 or 42 h was higher (p < 0.05) than that of oocytes matured for 36 h (95-96% vs. 79%). Cleavage (83%) and blastocyst formation (26%) were significantly higher (p < 0.05) in oocytes matured for 42 h than in other groups. Supplementation of a defined maturation medium with 100 µM CYS or 100 µM β-ME showed no stimulatory effect on oocyte maturation, embryo cleavage, or blastocyst formation after PA. β-ME treatment during IVM decreased embryo cleavage after SCNT compared to pFF or PVA treatments, but no significant difference was found in blastocyst formation (7-16%) among the four treatment groups. The results indicated that maturation of oocytes for 42 h was beneficial for the development of SCNT embryos. Furthermore, the defined maturation system used in this study could support in vitro development of PA or SCNT embryos. 相似文献
6.
Background
Prior to the present study, the seroprevalence of leptospirosis in Irish suckler herds was unknown. In this study, we describe the herd and animal-level prevalence of Leptospira Hardjo infection in the Irish suckler cattle population. For the purposes of the study, the 26 counties of the Republic of Ireland were divided into 6 regions from which a representative number of herds were selected. A herd was considered eligible for sampling if it was not vaccinating against leptospirosis and if it contained ≥ 9 breeding animals of beef breed ≥ 12 months of age. In total, 288 randomly selected herds were eligible for inclusion in the seroprevalence dataset analysis. Serological testing was carried out using a commercially available monoclonal antibody-capture ELISA, (sensitivity 100%; specificity 86.67%).Results
Herds were categorised as either “Free from Infection” or “Infected” using the epidemiological software tool, FreeCalc 2.0. Using this classification, 237 herds were “Infected” (82.29%). The South West and South East regions had the highest herd prevalence. The regional effect on herd prevalence was largely mirrored by breeding herd size. A true animal-level prevalence of 41.75% was calculated using the epidemiological software tool, TruePrev. There was a statistically significant regional trend, with true prevalence being highest in the South East (P < 0.05). The median Breeding Herd Size (BHS), when categorised into quartiles, had a statistically significant influence on individual animal true seroprevalence (P < 0.001); true seroprevalence increased with increasing BHS.Conclusions
Leptospirosis is a widespread endemic disease in the Republic of Ireland. It is possible that economic losses due to leptospirosis in unvaccinated Irish suckler herds may be underestimated. 相似文献7.
遮阴对大豆幼苗光合和荧光特性的影响 总被引：5，自引：0，他引：5
为了探寻不同遮阴条件下大豆幼苗叶片的光合响应机理及寻求适度的遮阴比例,本试验模拟田间玉/豆套作,以强耐阴“南豆12号”和弱耐阴“桂夏3号”2个大豆品种为材料,在不遮阴、半侧遮阴(30%,50%,70%)和全遮阴(50%)5个不同遮阴方式下,测定了不同生育期遮阴和复光后大豆幼苗叶片色素含量、光合速率和叶绿素荧光参数的变化。结果表明,随着遮阴程度增加,大豆幼苗叶片的色素含量和初始荧光强度(F0)增加,叶绿素a/b值变小;光合速率(Pn)、最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)和光化学淬灭系数(qP)呈先升后降趋势,非光化学淬灭系数(NPQ)则呈先降后升的趋势。遮阴胁迫对2个大豆品种幼苗第四复叶期的影响最为显著。2个品种间比较,“南豆12号”和“桂夏3号”在弱遮阴下都能通过改变色素组分比例、促进光合电子传递等途径提高光能潜力的利用来适应弱光环境。在强遮阴胁迫下,“南豆12号”的PSⅡ反应中心抗胁迫能力更强,“桂夏3号”则不能及时耗散过剩光能,导致光合机构受到破坏。 相似文献
8.
A.J. German J.M. Titcomb S.L. Holden Y. Queau P.J. Morris V. Biourge 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2015,29(6):1547-1555
Background
Most weight loss studies in obese dogs assess rate and percentage of weight loss in the first 2–3 months, rather than the likelihood of successfully reaching target weight.Objective
To determine outcome of controlled weight loss programs for obese dogs, and to determine the factors associated with successful completion.Animals
143 obese dogs undergoing a controlled weight loss program.Methods
This was a cohort study of obese dogs attending a referral weight management clinic. Dogs were studied during their period of weight loss, and cases classified according to outcome as “completed” (reached target weight), “euthanized” (was euthanized before reaching target weight), or “stopped prematurely” (program stopped early for other reasons). Factors associated with successful completion were assessed using simple and multiple logistic regression.Results
87/143 dogs (61%) completed their weight loss program, 11 [8%] died or were euthanized, and the remaining 45 [32%] stopped prematurely. Reasons for dogs stopping prematurely included inability to contact owner, refusal to comply with weight management advice, or development of another illness. Successful weight loss was positively associated with a faster rate (P < .001), a longer duration (P < .001), and feeding a dried weight management diet (P = .010), but negatively associated with starting body fat (P < .001), and use of dirlotapide (P = .0046).Conclusions and Clinical Relevance
Just over half of all obese dogs on a controlled weight loss program reach their target weight. Future studies should better clarify reasons for success in individual cases, and also the role of factors such as activity and behavioral modification. 相似文献9.
Sang Tae Shin Sung Keun Jang Hong Suk Yang Ok Keun Lee Yhong Hee Shim Won Il Choi Doo Soo Lee Gwan Sun Lee Jong Ki Cho Young Won Lee 《Journal of veterinary science (Suw?n-si, Korea)》2008,9(1):103-107
This study was performed to produce transgenic Korean native goat (Capra hircus) by laparoscopic embryo transfer (ET) to overcome the limitations of ET performed by laparotomy. Transgenic embryos were produced by DNA pronuclear microinjection of in vivo zygotes. The recipient goats were synchronized for estrus by using an introvaginal progesterone devices as a controlled internal drug-releasing insert (CIDR) for 13 days and injection of 400 IU PMSG 48 h before removal of the insert. Embryos were transferred on day 3 and 4 after removal of the insert. Recipient goats were deprived of feed for 48 h, then suspended in a laparotomy cradle at an angle of 45°. After obtaining a sufficient pneumoperitoneum, the laparoscope and forceps were inserted abdominally through 5 mm trocar sleeves. Examination of the ovaries and uterus was performed and then 213 embryos were transferred into the oviducts via the infundibula of 76 recipient goats. To compare pregnancy rates, ET was also performed by laparotomy in 82 recipient goats. The pregnancies in the recipient goats were diagnosed by ultrasound on day 30 after embryo transfer. The pregnancy rate with laparoscopic ET was significantly higher than with ET performed by laparotomy (46.1% vs. 28.6%, p < 0.05). In addition, the pregnancy rates were compared between ovulated and non-ovulated ovaries of the recipient goats in the laparoscopic ET group. No significant difference was observed between the pregnancy rates of ovulated and non-ovulated ovaries (41.3% vs. 33.3%, p < 0.05) suggesting that ET may also be possible in non-ovulated recipients through artificial rupture of Graafian follicles. These results suggest that laparoscopic ET is a highly efficient method for the transfer of goat embryos. 相似文献
10.
海滨雀稗具有耐盐、对灌溉水质要求不高的特性。 用它建植的草坪可以降低淡水资源的消耗和浪费,但目前我国还没有自己育成的海滨雀稗品种,只能通过国外引进。本实验以海滨雀稗4个品种Sea Isle 2000、Platinum、Supreme、Salam为材料,利用60Co-γ射线以0.12 Gy/min 的强度在0,40,45,50,55 Gy 5个剂量下分别照射种茎,从辐照群体中寻找突变材料,对突变材料从叶宽、叶长、株高、匍匐茎节间长度和直径以及密度等坪用性状进行观测分析,研究其植株形态变异的诱变效应,并从中选育性状优良的突变材料。结果表明,材料经辐射后,不同海滨雀稗品种对60Co-γ辐射的敏感性不同。经过3个阶段的扩繁、筛选,Sea Isle 2000选出3个突变体,Platinum选出3个突变体,Supreme选出1个突变体,Salam选出2个突变体,初步共选育出9个突变材料。所有突变材料的植株叶宽、叶长、株高、匍匐茎节间长度和直径以及密度等指标均不同程度地优于各自对照。综合来看,突变材料“SI-50-1”、“PL-40-2”、“SLM-45-1”叶片短细、节间缩短、株高矮化、成坪密度高,辐射诱变效果最明显,为新品种选育提供了优异的育种新材料。 相似文献
11.
在陇东旱作区,采用全膜双垄沟、全膜平铺、半膜平铺和露地(传统种植)4种栽培方式,种植了具有代表性的两个光敏型高丹草品种“海牛”和“大卡BMR”,测定并分析了两个品种不同发育阶段干物质积累、主要营养成分含量和产量及其这些特征的动态变化规律,以期确定该类牧草的最佳栽培和饲用技术。结果表明,在旱作4种栽培方式下,随生长发育进程的延长,两品种的粗蛋白(CP)含量逐渐下降,中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量整体呈“升-降-升”的变化趋势,总可消化养分(TDN)含量整体呈“降-升-降”的变化趋势,糖锤度(BX)含量整体呈逐渐上升的变化趋势。在植株生长后期(出苗后126和140 d),品种对CP和NDF含量影响不显著(P>0.05),对ADF、TDN和BX含量影响显著(P<0.05),其中褐色中脉型(BMR)品种“大卡”的ADF含量较低,平均分别为33.13%和40.39%,TDN含量相应较高,平均分别为58.14%和52.24%,非BMR型品种海牛的BX含量较高,平均分别为12.41%和14.59%。栽培方式对各营养成分含量影响均不显著(P>0.05),其中在不覆膜和半覆膜处理下ADF含量较低,在出苗后126 d平均分别为34.39%和34.01%,在出苗后140 d平均分别为39.98%和40.60%;而TDN含量相应较高,在出苗后126 d平均分别为57.42%和57.34%,在出苗后140 d平均分别为52.66%和52.20%。CP和TDN产量受品种及栽培方式的影响显著(P<0.05),且与干物质产量表现一致,可消化营养物质含量和干物质产量相对平衡点在126 d前后。因此,从饲草生产角度考虑,作青贮饲料利用时,选择BMR型品种“大卡”在全膜双垄沟或全膜平铺的栽培方式下种植,并于出苗后120~140 d收获为最佳栽培饲用模式。 相似文献
12.
Interrelationships among Production and Clinical Disease in Dairy Cattle: A Review 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Erb HN 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(6):326-329
Epidemiological evidence is presented in order to answer two questions. The first question is: “Does high milk production put a cow at increased risk of disease?” The answer to this question seems to be “maybe” for milk fever, but “no” for most other common diseases (veterinary-assisted dystocia, retained placenta, metritis, cystic ovary, ketosis, left displaced abomasum, and mastitis). The second question is: “Is low milk production a consequence of disease?” For most diseases the answer is a cautious “yes”. 相似文献
13.
不同培养体系对牛胚胎体外发育的影响 总被引：2，自引：0，他引：2
采用离子霉素和6-二甲氨基嘌呤(6-DMAP)对牛体外成熟卵母细胞进行联合激活,激活后采用不同的培养体系进行体外培养,观察不同的培养液对牛孤雌激活胚体外发育能力的影响。3种培养体系分别为:A(0~48 h:CR1aa+3 mg/mL BSA;48 h~7 d:CR1aa+10%FBS),B(连续7 d均为SOFaa+3 mg/mL BSA),C(0~5 d:SOFaa+3 mg/mL BSA;6~7 d:SOFaa+10%FBS)。结果表明:3种培养液对卵裂率没有显著性影响,分别为87.22%,94.33%和91.30%,但囊胚发育率存在显著性差异,以A效果最好,其囊胚发育率为25.56%;C次之,囊胚发育率为11.80%;B最低,囊胚发育率为3.55%。之后选择最佳的培养液进行体外受精实验,结果表明CR1aa可用做牛胚胎体外生产的培养液。 相似文献
14.
干旱胁迫对鸭茅根、叶保护酶活性、渗透物质含量及膜质过氧化作用的影响 总被引：3，自引：0，他引：3
以2种不同耐旱性的鸭茅基因型(敏感型“01998”和耐旱型“宝兴”) 为研究对象,研究干旱胁迫下鸭茅根、叶膜质过氧化作用,渗透调节和保护酶活性的生理变化,探讨鸭茅耐旱机制。结果表明, 随着干旱胁迫时间的延长,2种基因型鸭茅根系及叶片电导率,丙二醛含量逐渐增加,渗透调节物质可溶性糖和游离脯氨酸不断积累,而可溶性蛋白含量、超氧化物歧化酶、过氧化氢酶、过氧化物酶和抗坏血酸过氧化物酶活性呈先上升后下降趋势。其中,叶片脂膜过氧化产物MDA累积和膜透性增幅较大,说明在持续的干旱胁迫下叶片所受伤害重于根系。而渗透物质积累方面,叶片中可溶性糖和可溶性蛋白的含量高于根系,而根系中的游离氨基酸的相对增加量则大于叶片,这可能与叶片是糖的主要产生部位,而根系则可以合成氨基酸有关。研究还表明,干旱胁迫第24天,耐旱型品种“宝兴”根系及叶片APX、POD活性显著高于“01998” 表明重度干旱胁迫并没有降低APX和POD酶清除H2O2和单态氧的能力,说明“宝兴”鸭茅在干旱条件下抗氧化清除系统响应更积极、更持久。 相似文献
15.
为研究调节剂对芸豆光合作用及产量的调控机制,选用英国红芸豆为试验材料,采用大田完全随机试验方法,以初花期叶面喷施调节剂为处理,以喷施清水为对照,研究了50 mg·L-1烯效唑(S3307)和50 mg·L-1胺鲜酯(DTA-6)对芸豆开花期、结荚期和鼓粒期光合相关指标和产量的调控效应。结果表明:1)除DTA-6在结荚期的净光合速率略小外,S3307和DTA-6均不同程度地提高了开花期至鼓粒期的净光合速率、蒸腾速率、气孔导度和叶面积指数。2)S3307可提高结荚期至鼓粒期的叶绿素含量,DTA-6可降低开花期至鼓粒期叶绿素的分解速率。3)S3307和DTA-6可提高芸豆各时期的地上部单株干物质积累量,尤其是鼓粒期作用效果更显著,S3307和DTA-6较CK分别增加了14.55%和36.05%。4)与CK相比,S3307和DTA-6降低了开花期至鼓粒期的茎叶分配率,显著提高了鼓粒期的荚分配率,促进了植物同化物质由“源(叶)”向“库(籽粒)”的转移。5)S3307极显著提高了芸豆单株荚数,DTA-6极显著提高了单株荚数,显著提高了单株粒重,且S3307和DTA-6均显著提高了产量,分别较CK增产4.30%和10.16%。综合分析可知,S3307和DTA-6可有效提高芸豆生殖生长阶段的光合作用能力,促进植物的干物质积累以及荚的分配,提高芸豆产量,且DTA-6的增产率更高。 相似文献
16.
Transfer of pig embryos to different uterine sites. 总被引：3，自引：0，他引：3
Embryo transfer in pigs normally involves surgery. In connection with the development of nonsurgical or endoscopic transfer techniques, it is important to know whether the uterine site to which embryos are transferred has an effect on the success rate. In the present investigation, prepubertal donor gilts were treated with 1,500 IU of PMSG and, 72 h later, with 500 IU of hCG. Gilts were artificially inseminated 24 and 36 h after hCG injection. Embryos at the expanded blastocyst stage were collected from donor gilts. Recipient gilts were treated synchronous with the donors, using 1,000 IU of PMSG followed, 72 h later, with 500 IU of hCG. After a maximum of 3 h in vitro, embryos (n = 15 to 20, mean = 17.3) were transferred surgically to the middle of the uterine horn, to the caudal quarter of the uterine horn, or to the uterine body. Recipients were slaughtered between 28 and 34 d after transfer. The pregnancy rate of the recipients was low when the embryos were deposited in the uterine body (12%), compared with the middle (88%) or the caudal quarter of the uterine horn (81%) (P < .01). The corresponding average number of viable fetuses per pregnant recipient was 8.2 in the uterine body, 5.6 in the middle, and 4.5 in the caudal quarter. Average survival rate of embryos after transfer to the middle of the uterine horn was 41% vs 29 and 3% after transfer to the caudal quarter or the uterine body, respectively (P < .01). Hence, the uterine body seems to be an unsuitable site for embryo transfer in pigs. These results may explain the unsatisfactory results achieved with nonsurgical embryo transfer in the past. 相似文献
17.
The aim of this study was to reconstruct and cryopreserve somatic cell nuclear transferred (SCNT) ovine embryos and evaluate the effect of alpha-tocopherol on blastocyst development and subsequent cryosurvival of the SCNT embryos. The alpha-tocopherol (100 microg/ml) was added into culture medium for the SCNT embryos, the yield and total cell numbers of blastocysts were determined and the apoptosis incidences of the blastocysts were evaluated using the TUNEL assay. The blastocysts from the alpha-tocopherol and untreated groups were then frozen-thawed, and their cryosurvival was assessed by in vitro culture for 48 h. The results showed that there were no significant differences in blastocyst yield (26.3 vs. 22.3%) and total cell number (68.2 vs. 64.3) between the alpha-tocopherol and untreated groups. However, addition of alpha-tocopherol to the culture medium significantly decreased the apoptotic cell number (3.4 vs. 5.5) and significantly increased the cryosurvival of SCNT blastocysts (66.8 vs. 50.7%). In conclusion, addition of alpha-tocopherol to SCNT embryo culture medium was beneficial for improving embryo quality by decreasing the apoptotic blastocyst cell number and improving the tolerance of the embryos to cryopreservation. 相似文献
18.
19.
在黄土高原雨养农业区,以光敏型高丹草品种“大卡BMR”和“海牛”为材料,采用8.33、12.50和16.67万穴·hm-2 3个低、中、高密度全膜平铺穴播种植,在植株不同生长阶段,测定了粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、总可消化养分(TDN)和糖锤度(BX)含量,以研究光敏型高丹草在当地的最佳种植密度和收获时期。结果表明:生长发育进程在植株营养形成过程中占主导地位。在品种间,两品种生长前期CP含量差异较大(P<0.05);“大卡BMR”的NDF、ADF和BX整体低于“海牛”,TDN含量高于“海牛”。密度对营养成分有影响,CP含量随密度的增大有所降低;密度对BX含量前期影响较大(P<0.05),中后期影响不明显(P>0.05);在全生长期内NDF和ADF含量整体上高密度处理明显低于(P<0.05)低密度处理;密度对TDN含量影响明显(P<0.05),生长后期(出苗后126~140 d)依次均为高密度>中密度>低密度。营养成分和产量的动态变化表现为,两品种随生长发育进程的延长,CP含量均呈逐渐下降的变化趋势,BX均呈逐渐上升的变化趋势,NDF和ADF含量均呈“升—降—升”的变化趋势,TDN含量均呈“降—升—降”的变化趋势;在出苗后126~140 d,干物质产量仍在上升,CP和TDN产量平稳,TDN的含量处于下降趋势。这种动态变化为北方不抽穗或能抽穗不能成熟的光敏型高丹草最佳刈割期的决策提供了重要依据。从饲草生产角度考虑,在春播一茬青贮收割模式下,当地以“大卡BMR”品种较好,种植密度以每公顷12.50万穴较好,两品种均在出苗后126~140 d(9月上中旬,大卡BMR处于抽穗期、海牛处于开花期)刈割最佳。 相似文献
20.
A 2 X 2 cross-classified experiment was conducted to investigate the effect of age of equine embryo (7 vs 8 d postovulation) and method of transfer (surgical vs nonsurgical) on pregnancy rates at 50 d of gestation. Embryos were recovered 7 or 8 d postovulation using a Foley catheter and 3 liters of modified Dulbecco's phosphate-buffered saline (PBS). Upon identification, the embryos were placed in millipore-filtered PBS containing 20% heat-inactivated steer serum and maintained at room temperature until transferred. At the time of recovery, embryos were randomly assigned to be transferred either nonsurgically using a sterile insemination pipette or surgically via a flank incision. For nonsurgical transfer, the embryo was deposited into the uterine body; whereas, in surgical transfer, the embryo was placed in the uterine horn ipsilateral to the corpus luteum. Recovery rates for embryos collected on d 7 (75.5%) or 8 (81.9%) were similar (P greater than .05). Age of embryo did not affect (P greater than .05) pregnancy rate. At 50 d, pregnancy rates were 60 and 57% for mares receiving d 7 or 8 embryos. However, more (P less than .05) pregnancies were obtained after transfer of embryos surgically (72%) than nonsurgically (45%). More (P less than .05) pregnancies were obtained after transfer of d 8 embryos surgically (75%) compared with nonsurgically (40%). Within method of transfer, pregnancy rates were similar (P less than .05) for surgical transfer of d 7 and 8 embryos (69 and 75%), but tended (P less than .25) to be higher for nonsurgical transfer of d 7 embryos (50%) compared with d 8 embryos (40%).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献