对不同类型饲料混合机最佳混合时间的研究

试验以混合均匀度为观测指标研究了4种饲料混合机——小型腰鼓式混合机、中型腰鼓式混合机、锥形悬臂双螺旋行星式混合机和卧式双螺旋环带式混合机在0.6的装载系数下的最佳混合时间。物料为膨润土和麦芽根粉,示踪剂为硫酸亚铁。测定各时间点样品中的亚铁离子含量,用于计算CV。结果表明:这4种混合机的最佳混合时间分别为4、6、8、5min;混合时间过短或过长均会降低饲料产品的混合均匀度。     

添加干物料混合时间对苜蓿贮前均匀度和含水量的影响

为明确混合时间与紫花苜蓿（Medicago sativa）混合青贮均匀度和含水量之间的关系,提供科学合理的苜蓿混合青贮工艺。本试验以80%、75%、70%、65%含水量苜蓿（M）为材料,选择玉米粉和麸皮（Y）作为添加剂,根据适宜含水量（60%）共设计7个添加处理（80%M+10%Y、80%M+15%Y、75%M+10%Y、75%M+15%Y、70%M+10%Y、70%M+15%Y、65%M+5%Y）,5个混合时间处理（3、5、7、9、11 min）,采用筛分法测定混合均匀度,烘箱烘干法测定苜蓿混合青贮发酵前含水量。结果表明：混合时间为5 min时,各处理的混合均匀度均可达到90%以上,其中70%M+10%Y混合均匀度最佳,为93.47%;混合时间为7 min时,80%M+15%Y混合均匀度最佳,为95.44%;混合青贮发酵前,65%M+5%Y的含水量随着混合时间的延长逐渐接近60%;75%M+15%Y的含水量在混合7 min时最接近60%,为59.41%。因此,合适的混合时间有利于调节苜蓿混合青贮均匀度和含水量,进而改善其发酵品质。     

不同装载系数和混合时间对添加剂预混料混合均匀度的影响

混合是配合饲料生产的重要工序,为了研究不同装载系数和混合时间对配合饲料混合均匀度的影响,探求悬臂非对称双螺锥形混合机在添加剂预混料生产中合理的装载系数和最佳的混合时间。采用甲基紫示踪法、以添加剂预混料为物料对象,采用两因素交叉设计就2个装载系数(500kg和250kg料位)和4个不同混合时间(16、18、20、22min)对饲料混合均匀度的影响进行研究。结果表明:混合机的料位为250kg(装载系数为0.3)时的混合均匀度显著低于500kg料位(装载系数0.6)的(P<0.05),但在低料位时通过选择合适的混合时间也能取得较满意的混合效果(CV为3.21%);4个不同的混合时间中以20min为最佳,混合时间过短或过长均降低饲料产品的混合均匀度。     

二次正交旋转组合设计优化肉羊TMR加工工艺

试验旨在通过单因素试验和二次正交旋转组合设计,研究肉羊全混合日粮(TMR)加工中各种原料的最佳混合时间参数。首先使用单因素试验方法,研究精料补充料(3、5、7、9、11 min)、羊草(10、15、20、25、30 min)和全株玉米青贮(3、6、9、12、15 min)混合时间对肉羊TMR的物理有效中性洗涤纤维、容重及混合均匀度的影响,再通过二次回归正交旋转组合设计,以混合时间为自变量,TMR混合均匀度为因变量拟合回归方程,确定三种原料的最佳混合时间范围。结果表明:精料补充料、羊草和全株玉米青贮混合时间对TMR物理有效中性洗涤纤维和混合均匀度均有显著影响(P<0.05),而对TMR容重无显著影响(P>0.05);经过二次正交旋转组合设计优化试验,确定了精料补充料、羊草、全株玉米青贮的最佳混合时间范围为:4.89～5.91、23.09～26.08、4.84～6.54 min。     

不同混合机最佳混合时间测定的试验研究

研究旨在探讨腰鼓型混合机和V型混合机混合时间对混合均匀度的影响,以确定满足生产实际的最佳混合时间。以扬州大学饲料厂生产的复合预混料为试验材料,采用单因子分组试验,按混合时间分7个处理组,每个处理做3个重复,每个重复取10个样品。采用邻菲罗啉比色法测定其变异系数。结果表明:在装载系数为0.42工况下,腰鼓型混合机的最佳混合时间为4 min,对应的变异系数(CV)为4.68%,混合时间对变异系数有显著影响(P<0.05)。V型混合机的最佳混合时间为11 min,变异系数(CV)为4.19%,混合时间对变异系数影响极显著(P<0.01)。实际生产中应根据不同机型选择适宜的混合时间。     

小麦为示踪物研究奶牛日粮混合均匀度和颗粒度

全价混合日粮(Total mixed ration,TMR)的制作是奶牛饲养技术的关键,而混合均匀度是全价混合日粮重要的评价指标。本试验通过示踪物小麦不同的添加量水平、不同的搅拌时间、不同的采样点对奶牛的日粮进行混合均匀度和颗粒度测定。结果表明:搅拌机不同搅拌时间8 min、12 min和16 min对奶牛TMR混合均匀度差异不显著(P0.05),但8 min组的整齐度要优于12 min和16 min组,平均的混合均匀度8 min组也要高于12 min和16 min组;1%小麦添加量传送带和料车奶牛TMR的混合均匀度差异不显著(P0.05),但4%小麦添加量组中8 min传送带样本与料车差异显著(P0.05)。而1%和4%小麦添加量组饲槽TMR的混合均匀度均显著低于搅拌8 min时传送带上TMR的混合均匀度(P0.05)。本研究首次以小麦为奶牛全价混合日粮的示踪物,为奶牛全价混合日粮混合均匀度检测方法、考察搅拌机的混合性能和确定最佳混合时间提供了依据。     

不同搅拌机和搅拌时间对复合预混料混合均匀度的影响

试验以4%猪用复合预混料为预混材料,研究双轴高效卧式搅拌机搅拌60s、90s、120s,“V”型搅拌机搅拌20min、25min、30min,卧式桨叶式搅拌机搅拌5min、10min、15min、20min对复合预混料混合均匀度的影响,结果表明:①采用双轴高效卧式搅拌机搅拌60～120s,复合预混料的均匀度都较高,搅拌90s的均匀度优于60s,但与120s较接近,说明双轴高效卧式搅拌机搅拌90s已足够(CV<4.5%);②当“V”型搅拌机搅拌时间从20min增加到25min,复合预混料的混合均匀度明显提高,但继续增加搅拌时间,均匀度反而下降,“V”型搅拌机搅拌25min效果为佳(CV<2.5%);③卧式搅拌机搅拌时间从5min增加到10min,复合预混料的混合均匀度明显提高,之后,随搅拌时间增加,均匀度趋于降低,卧式桨叶式搅拌机搅拌10min为宜(CV<2.5%);④除卧式桨叶式搅拌机搅拌5min外,其它各机型的各搅拌时间处理,复合预混料的均匀度都基本可满足变异系数小于5%的要求,确保良好的均匀度。根据本试验结果,建议用量较大、均匀度要求略低些的4%～5%预混料可选用效率高的双轴高效卧式搅拌机,而用量小、均匀度要求较高0.5%～1%预混料,建议选用“V”型搅拌机或卧式桨叶式搅拌机。     

立式饲料预混机混合性能测定试验

通过盐法原理,以CV(混合均匀度变异系数)作为混合均匀度评定指标,确定饲料预混机最佳混合时间和最小适宜混合时间。制作特性曲线(CV-t曲线图),反映出饲料的混合均匀度与混合时间呈近似倒抛物线形关系。以试验确定的DSH-0.5型立式行星双螺旋混合机的最小适宜混合时间为24min左右。8～16min时段CV基本趋于稳定,但25min后CV有增大趋势,即混合时间过长,可能出现分级现象。     

东北寒区高丹草与紫花苜蓿混合青贮适宜比例研究

为确定适合东北寒区高丹草和紫花苜蓿的最佳青贮比例,试验以高丹草和紫花苜蓿为青贮原料,分别按照5:5、6:4、7:3、8:2的比例进行混合青贮,并在此基础上设置添加5% CaCO3和不添加5% CaCO3的试验处理,不添加紫花苜蓿和CaCO3的高丹草为对照组。结果表明：在各试验处理的组合中,以不添加 CaCO3的高丹草与紫花苜蓿以5:5混合配比时,其营养品质中酸性洗涤纤维（ADF）含量为35.53%、中性洗涤纤维（NDF）含量为47.43%,显著低于对照组和添加CaCO3的处理|粗蛋白质（CP）含量为17.83%,显著高于对照组和添加CaCO3的处理。发酵品质中,V-Score评分结果显示对照组和不添加CaCO3处理的的混合青贮均高于90分。综合考虑混合青贮的营养品质和发酵品质得出,在东北寒区,添加紫花苜蓿能够显著提高混合青贮的饲用品质,且高丹草和紫花苜蓿混合青贮的最佳配比为5:5,并且不宜添加CaCO3。 [关键词] 东北寒区|高丹草|紫花苜蓿|混合青贮     

牛初乳粉片混合工艺的优化研究

为提高牛初乳粉片的混合工艺的混合均匀度,采用响应面试验设计优化混合工艺参数。在单因素试验的基础上,确定采用投料方式Ⅲ,以混合时间、装载系数为主要影响因素,以混合均匀度为响应值,采用响应面法对混合工艺参数进行优化。结果表明:牛初乳粉片混合工艺最优参数为:混合时间15 min,装载系数35%,混合均匀度为94.68%,与模型预测的理论值96.52%均比较接近。采用响应面分析优化得到的牛初乳粉片混合工艺参数具有可行性和可靠性,可用于实际操作。     

Diet mixing time affects nursery pig performance

The objective of this study was to determine the effects of mixing time (mixer efficiency) of diets containing several low-inclusion ingredients (crystalline AA, ZnO, a medication, and vitamin and trace mineral premixes) on growth performance of nursery pigs. In a pilot study, mixing efficiency of a 1,360-kg capacity, horizontal ribbon mixer was evaluated with salt of different particle sizes (440, 730, 2,000, and 3,000 microm). Sample preparation was evaluated by analyzing diet samples as collected (unground) or by grinding the entire sample to approximately 400 microm in particle size (ground). Diets (907 kg) were mixed, and samples were collected after 0, 30, 60, 120, 210, 330, 480, and 630 s of mixing. The coefficient of variation among 10 samples for each mixing time was used to measure mixer efficiency as determined by Cl concentration. A salt particle size x sample preparation x mixing time interaction was observed (P = 0.04). Samples with 2,000- or 3,000-microm salt particle size (unground or ground) never reached the desired mixing efficiency of a 10% CV. Using 440-microm salt (unground or ground) or 730-microm salt particle sizes (ground) was necessary to accurately achieve a mixing efficiency of a <10% CV within 330 and 630 s, respectively. Next, 180 weanling pigs (PIC, 6.31 +/- 0.84 kg of BW, 21 +/- 3 d of age) were fed diets in 2 phases (d 0 to 14 and d 14 to 28). Treatments consisted of mixing diets for 0, 30, 60, 120, or 330 s (440-microm salt particle size). Samples were collected in the mixer, and then each bag of feed (22.5 kg) was labeled (first to last as-manufactured) and sampled to determine the mixing efficiency. An individual bag of feed was fed to a single pen of pigs, and when finished, the next sequential bag was used. As mixing time increased, mixer CV were 178, 38, 26, 21, and 5% for phase 1 and 172, 79, 60, 48, and 26% for phase 2. As mixing time increased, bag CV values were 26, 20, 16, 11, and 7% for phase 1 and 56, 45, 40, 33, and 12% for phase 2. From d 0 to 14, increasing mixing time increased ADG (linear, P < 0.01) and G:F (quadratic, P = 0.03). From d 0 to 28, increasing mixing time increased ADG (quadratic, P < 0.01) and G:F (linear, P = 0.04). These data demonstrate that inadequate diet mixing (CV > 12%) reduces nursery pig performance.     

假俭草杂交后代生殖性状遗传及相关性分析

选用假俭草2份生殖性状存在差异的种源材料E102和E092(1)进行杂交,获得F₁分离群体,应用植物数量性状主基因＋多基因混合遗传模型分析方法对F₁群体的花序密度、生殖枝高度、每穗粒数和花序长度等生殖性状进行遗传分析,已初步明确假俭草上述性状的遗传特性。结果表明,1)在调查的杂交后代的4个生殖性状中,变异系数由大到小依次为花序密度(54.10%)>生殖枝高度(13.17%)>每穗粒数(8.92%)>花序长度(8.42%),变异系数最大的为花序密度,最小的为花序长度。2)花序密度的最佳遗传模型为A-4模型,即一对主基因模型,该主基因表现为负向完全显性,即显性效应等于负的加性效应,主基因遗传率为60.71%。生殖枝高度的最佳遗传模型为B-1模型,即2对主基因,加性－显性－上位性模型,主基因遗传率为93.73%。花序长度也是B-1模型,主基因遗传率为96.79%。每穗粒数最佳遗传模型均为A-0模型,即无主基因模型。性状间相关分析结果表明,叶片长度与叶片宽度、叶片长度与草层高度之间呈极显著的正相关,相关系数分别是0.417 8和0.628 5;生殖枝高度与花序密度、生殖枝高度与每穗粒数之间呈显著的正相关,相关系数分别为0.374 8和0.356 2;生殖枝高度与草层高度之间呈极显著正相关,相关系数为0.423 0。     

Disappearance of acetic acid from the bovine reticulorumen at basal and elevated concentrations of acetic acid.

Disappearance of acetic acid was quantified to determine whether removal of this acid from the reticulorumen is altered when ruminal acetic acid concentrations are elevated. Ruminally fistulated beef steers (n = 3 per experiment; BW = 320 +/- 9 kg) were fed eight times daily a 46% corn-based concentrate:54% mixed hay diet to meet maintenance energy requirements (3.5 kg of DM/d). In situ production of acetic acid, determined by pulsed-continuous infusion of [1-14C]acetic acid, was 530 mmol/h (CV = 12%). Disappearance from the reticulorumen (i.e., presumed absorption) was 460 mmol/h (CV = 2%) or 87% (CV = 2%) of ruminal production. Variation is described within an operational steady state. Acetic acid concentrations were increased by continuous infusion of unlabeled acetic acid into the reticulorumen. Ruminal disappearance (mmol/h) increased when this simulated production was elevated up to and exceeding in situ rates reported previously (530 to 2,700 mmol/h). These data suggest that two-thirds to three-fourths of ruminal acetate production disappeared across the reticuloruminal wall when concentration was elevated; the complement exited from the rumen with the liquid phase. The reticulorumen has an additional capacity to remove acetic acid; however, it does so with an apparent reduced efficiency at higher production rates. Liquid out-flow may affect the efficiency of reticuloruminal disappearance. Sites distal to the rumen become quantitatively important when ruminal acetic acid concentrations are increased.     

Development of a water-in-oil-in-water adjuvant for foot-and-mouth disease vaccine based on ginseng stem-leaf saponins as an immune booster

There has been an increasing interest in finding new formulations that qualify as vaccine adjuvants, which must be safe, stable, and have the capacity to stimulate a strong immune response. In this study, a basic formulation of a water-in-oil-in-water (W/O/W) adjuvant CV13 was developed, and ginseng stem-leaf saponins (GSLS) were added as an immune booster into oil phase. The physicochemical properties of the adjuvant were tested. Furthermore, the immune activity and the adjuvant effects, as indicated by the foot-and-mouth disease virus (FMDV) antigen were evaluated. The results showed that CV13 was similar in appearance to ISA 206 and could package FMDV antigen into a stable W/O/W emulsion. The FMD vaccine prepared with CV13 alone or CV13 containing GSLS achieved pharmaceutical characteristics comparable to a vaccine prepared with ISA 206, moreover the structural stability of the CV 13 vaccine was found to be better. Mice that were immunized with the FMD vaccine prepared with CV13 containing GSLS presented a significantly higher LPBE antibody titer and splenocyte proliferation rate than those immunized with a vaccine prepared with CV13 alone (p < 0.05). In addition, there was no significant difference between the groups that were immunized with FMD vaccine prepared with CV13 containing GSLS and ISA206 in terms of cellular and humoral immune response. In this paper, CV13 containing GSLS shows excellent immunologic adjuvant effect in mice model, and this new adjuvant may provide a potential choice for FMD vaccine production in the future.     

The effect of changing the mode of ventilation on the arterial-to-end-tidal CO2 difference and physiological dead space in laterally and dorsally recumbent horses during halothane anesthesia

OBJECTIVE: To evaluate the effect of changing the mode of ventilation from spontaneous to controlled on the arterial-to-end-tidal CO2 difference [P(a-ET)CO2] and physiological dead space (VD(phys)/VT) in laterally and dorsally recumbent halothane-anesthetized horses. STUDY DESIGN; Prospective, experimental, nonrandomized trial. ANIMALS: Seven mixed breed adult horses (1 male and 6 female) weighing 320 +/- 11 kg. METHODS: Horses were anesthetized in 2 positions-right lateral and dorsal recumbency-with a minimum interval of 1 month. Anesthesia was maintained with halothane in oxygen for 180 minutes. Spontaneous ventilation (SV) was used for 90 minutes followed by 90 minutes of controlled ventilation (CV). The same ventilator settings were used for both laterally and dorsally recumbent horses. Arterial blood gas analysis was performed every 30 minutes during anesthesia. End-tidal CO2 (PETCO2) was measured continuously. P(a-ET)CO2 and VD(phys)NT were calculated. Statistical analysis included analysis of variance for repeated measures over time, followed by Student-Newman-Keuls test. Comparison between groups was performed using a paired t test; P < .05 was considered significant. RESULTS: P(a-ET)CO2 and VD(phys)/VT increased during SV, whereas CV reduced these variables. The variables did not change significantly throughout mechanical ventilation in either group. Dorsally recumbent horses showed greater P(a-ET)CO2 and VD(phys)/VT values throughout. PaCO2 was greater during CV in dorsally positioned horses. CONCLUSIONS AND CLINICAL RELEVANCE: Changing the mode of ventilation from spontaneous to controlled was effective in reducing P(a-ET)CO2 and physiological dead space in both laterally and dorsally recumbent halothane-anesthetized horses. Dorsal recumbency resulted in greater impairment of effective ventilation. Capnometry has a limited value for accurate estimation of PaCO2 in anesthetized horses, although it may be used to evaluate pulmonary function when paired with arterial blood gas analysis.     

Influence of energy intake on growth and utilisation of dietary protein and energy in germ-free and conventional chicks

The effect of metabolisable energy (ME) intake on the growth and utilisation of dietary protein and energy in germ-free (GF) and conventional (CV) chicks was investigated in two experiments. In experiment 1 a high energy diet (HED, 14.8 kJ ME/g) and a marginally-adequate energy diet (AED, 11.7 kJ ME/g) were fed to the GF and CV chicks at 240 g/2 birds/10 d. In experiment 2 a diet with 13.7 kJ ME/g was fed at 118 g (low level, LL) or 128 g (high level, HL)/bird/10 d. Body weight gain, protein retention and protein retention rate were similar in GF and CV chicks on both AED and HED in the first experiment, but in the second were higher in GF than in CV chicks. The increased ME intake of the CV chicks in experiment 2 may be too small to compensate for the increased requirement. ME intake was significantly higher in the CV chicks than in the GF chicks, whereas energy retention was similar in both groups.     

Pharmacokinetics of florfenicol in serum and synovial fluid after regional intravenous perfusion in the distal portion of the hind limb of adult cows

OBJECTIVE: To define the pharmacokinetics of florfenicol in synovial fluid (SYNF) and serum from central venous (CV) and digital venous (DV) blood samples following regional IV perfusion (RIVP) of the distal portion of the hind limb in cows. ANIMALS: 6 healthy adult cows. PROCEDURES: In each cow, IV catheters were placed in the dorsal common digital vein (DCDV) and the plantar vein of the lateral digit, and an indwelling catheter was placed in the metatarsophalangeal joint of the left hind limb. A pneumatic tourniquet was applied to the midmetatarsal region. Florfenicol (2.2 mg/kg) was administered into the DCDV. Samples of DV blood, SYNF, and CV (jugular) blood were collected after 0.25, 0.50, and 0.75 hours, and the tourniquet was removed; additional samples were collected at intervals for 24 hours after infusion. Florfenicol analysis was performed via high-performance liquid chromatography. RESULTS: In DV blood, CV blood, and SYNF, mean +/- SD maximum florfenicol concentration was 714.79 +/- 301.93 microg/mL, 5.90 +/- 1.37 microg/mL, and 39.19 +/- 29.42 microg/mL, respectively; area under the concentration versus time curve was 488.14 +/- 272.53 h*microg*mL(1), 23.10 +/- 6.91 h*microg*mL(1), and 113.82 +/- 54.71 h*microg*mL(1), respectively; and half-life was 4.09 +/- 1.93 hours, 4.77 +/- 0.67 hours, and 3.81 +/- 0.81 hours, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Following RIVP, high florfenicol concentrations were achieved in DV blood and SYNF, whereas the CV blood concentration remained low. In cattle, RIVP of florfenicol may be useful in the treatment of infectious processes involving the distal portion of limbs.     

假俭草杂交后代部分外部性状的遗传分析

选用假俭草2份外部性状存在差异的种源材料E102和E092(1)进行杂交,获得F₁分离群体,应用植物数量性状主基因+多基因混合遗传模型分析方法对F₁群体的叶片长度与宽度、节间长度与直径及草层高度等外部性状进行遗传分析,以初步明确假俭草上述性状的遗传特性。结果表明,1)在调查的杂交后代5个外部性状中,变异系数由大到小依次为叶片长度(23.39%)＞节间长度(21.89%)＞草层高度(15.32%)＞节间直径(7.41%)＞叶片宽度(6.77%),变异系数最大的为叶片长度,最小的为叶片宽度。2)叶片长度的最佳遗传模型为A-1模型,即1对主基因模型,该主基因表现为加性和部分显性或超显性, 主基因遗传率为68.98%;节间长度的最佳遗传模型为A-4模型,1对主基因模型,该主基因表现为负向完全显性,主基因遗传率为47.37%;草层高度的最佳遗传模型为B-6模型,即2对主基因模型,主基因表现为等显性模型,主基因遗传率为47.20%;叶片宽度和节间直径的最佳遗传模型均为A-0模型,即无主基因模型。     

Effects of Marker Selection and Mix Time on the Coefficient of Variation (Mix Uniformity) of Broiler Feed

An experiment was conducted evaluating several markers to determine mix uniformity. Treatment diet was a corn-soybean meal-based diet formulated for broiler chicks fed from 0 to 17 d posthatch. Dietary nutrients or tracers evaluated included the following: 1) dl-Met (99%), 2) l-Lys-HCl (78%), 3) CP, 4) mixing salt (chloride ion), 5) P, 6) Mn, 7) Fe particles (#40 Red, count), 8) Fe particles (#40 Red, absorbance), 9) Fe particles (RF-Blue Lake), 10) roxarsone, and 11) semduramicin. All minor and microingredients were individually hand-weighed and added to the mixer to insure accuracy and were added at the same location for all treatments. Diets were mixed using a double ribbon mixer for 3 different mix times (0.5, 2.5, and 5.0 min). Overall, from 0.5 to 5.0 min, all markers evaluated showed a numerical reduction in percentage of CV. Crude protein and P should not be considered as markers, because many different components in the batch of feed contribute some level of CP or P, and results can be confounding. dl-Methionine (99%) and l-Lys-HCl (78%) were the only markers that statistically reduced over time and had a CV < 10% (23.86 to 9.47% and 19.75 to 8.70%, respectively). These data suggest that mixer uniformity results can be influenced by the particular marker that is chosen for mixer uniformity analysis.     

Methods and reliability of echocardiographic assessment of left atrial size and mechanical function in horses

OBJECTIVE: To assess the feasibility, describe the techniques, and determine the reliability of transthoracic echocardiography for characterization of left atrial (LA) size and LA mechanical function in horses. ANIMALS: 6 healthy adult horses. PROCEDURES: Repeated echocardiographic examinations were performed independently by 2 observers in standing, unsedated horses by use of 2-dimensional echocardiography, pulsed-wave flow Doppler, and tissue Doppler imaging (TDI) techniques. Test reliability was determined by estimating measurement variability, within-day interobserver variability, and between-day inter- and intraobserver variability of all echocardiographic variables. Variability was expressed as the coefficient of variation (CV) and the absolute value below which the difference between 2 measurements will lie with 95% probability. RESULTS: Most echocardiographic variables of LA size had low overall variability (CV, < 15%). Among the 2-dimensional indices of LA mechanical function, area-based and volume-based ejection phase indices had moderate between-day variability (CV usually < 25%). Transmitral Doppler flow indices were characterized by low to high between-day variability (CV, 6% to 35%). The TDI wall motion velocities had high between-day variability (CV, > 25%), whereas most TDI-derived time intervals had low variability (CV, < 15%). CONCLUSIONS AND CLINICAL RELEVANCE: LA size and mechanical function can be reliably assessed in standing, unsedated horses by use of 2-dimensional echocardiography, transmitral blood flow velocity profiles, and analyses of LA wall motion by use of TDI. These results may provide useful recommendations for echocardiographic assessment of LA size and function in horses.