Studies on parturient paresis with special reference to the Downer cow syndrome

In addition to the classic form of parturient paresis characterized by hypocalcemia and somnolence, which responds rapidly to calcium therapy, it is not unusual to encounter other forms of this disease. The most common aberration would seem to be that in which the animals do not rise after calcium treatment. Many of these cows show little or no drowsiness, their appetite is often good, and the results of a clinical examination often negative. Some authors, Blood & Henderson (1960) for instance, consider that this “downer cow syndrome” is an indépendant disease not connected wiht milk fever.Although the downer cow syndrome is a common disease and is of considerable significance, remarkably little has been written about it. Garm in 1950 noted that the frequency of downers had increased as compared with the numbers registered a few years earlier. He had also noticed that in many of these cows hypocalcemia was present on the first day of illness but not on subsequent days, despite the fact that they had marked signs of milk fever. Osinga, in an investigation in 1963, compared two types of milk fever: a typical form in which the cow is drowsy, lies on her side, and has partial anorexia, and an atypical form in which the animal is alert and has normal or only slight loss of appetite. Osinga remarked that the atypical cases had in-creased in number and suggested as an explanation the fact that the amount of protein in the fodder has increased, with the result that auto-intoxication and damage to parenchymatous organs may occur.The object of the present investigation was to study the difference between cows that recover after treatment (“uncomplicated milk fever”) and those that have not risen 24 hrs. after the first treatment (“downers”). We also wanted to ascertain whether any changes occurred in the downers between the first and second, and second and third days. In addition, the difference between cows with blood-calcium levels equivalent to or over 8.0 mg/100 ml serum and those with corresponding values under 8.0 mg at the first examination was also studied.     

Acute rhabdomyolysis ("tying-up") in standardbred horses. A morphological and biochemical study

LINDHOLM, A., H.-E. JOHANSSON & P. KJÆRSGAARD: Acute rhabdomyolysis (“tying-up”) in standardbred horses. A morphological and biochemical study. Acta vet. scand. 1974, 15, 325–339. — Morphological, biochemical and histochemical changes were studied in muscle needle biopsy specimens (gluteus medius) from 59 standardbred trotters with acute clinical symptoms of the “tying-up” disease. All horses had increased levels of serum enzymes SGOT and SCPK. The biopsy specimens were taken at various intervals after onset of clinical symptoms (1–4 hrs., 18–24 hrs. and 2–20 days). Ry light microscopy it was shown that the muscular alterations had a focal distribution and were of the hyalin degeneration type with insignificant inflammatory reaction and slight calcification. The ultrastructural changes apparently commenced with myofibrillar waving, mitochondrial and sarcotubular alterations and terminated with myofibrillar degeneration and necrosis with invasion of inflammatory cells. The inflammatory cells were ultrastructurally similar to monocytes and macrophages. The degenerative changes mainly comprised fast twitch (FT and FTH) fibres as histochemically evidenced by myofibrillar ATPase and alkaline phosphatase staining.Riopsies from diseased muscle 1–4 hrs. after the onset of “tyingup” contained a low muscle concentration of glycogen, ATP and CP and a high concentration of lactate and glucose. Hence it is suggested that the described muscular alterations may be caused by a deranged carbohydrate metabolism caused by a local hypoxia.It was found that the “tying-up” disease resembled idiopathic rhabdomyolysis in man and was thus designated “equine rhabdomyolysis”.histochemistry; horse; rhabdomyolysis; skeletal muscle; “tying-up”; ultrastructure.     

Laboratory test descriptions for bovine respiratory disease diagnosis and their strengths and weaknesses: Gold standards for diagnosis,do they exist?

The diagnosis of bovine respiratory diseases (BRD) poses significant challenges to the clinician as there are numerous infectious etiologies, operating singly or most often in combination. Clinical signs alone may not be diagnostic and the diagnostic laboratory is often used to assist the clinician. Recently many molecular-based tests have been taken from the research laboratory to the veterinary diagnostic laboratory. This review describes the “traditional tests” and several “molecular tests” and discusses the benefits and limitations of the tests and their interpretation. Clinicians should consult with their diagnostic laboratory regarding the interpretation of the test results. The rate of development and use of molecular diagnostic tests have outpaced validation, standardization, and standards for interpretation relative to their use in BRD diagnostics.     

种植密度对光敏型高丹草营养成分及动态变化的影响

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。     

栽培方式对光敏型高丹草营养成分含量与产量的影响

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。     

海滨雀稗60Co-γ辐射诱变突变体筛选

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。     

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

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。     

Quantitative and qualitative assessment of the demand for veterinarians and animal health technologists in western Canada

A manpower survey of veterinary practices in western Canada found that there were potentially 314 full-time equivalent veterinary vacancies. However, only 8% of the respondents were in urgent need of another veterinarian. The results underscore that hiring intentions are best viewed as a continuum and not as a simple dichotomous variable: “Looking to hire? (Yes/No)”.     

不同品种高粱幼苗在干旱复水过程中的生理生态响应

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。     

Indirect fluorescent antibody techniques for demonstration of trout viruses and corresponding antibody

Two variations of the indirect fluorescent antibody technique (FAT) have been utilized in the work concerning two important virus diseases of trout, viral haemorrhagic septicaemia (VHS) and infectious pancreatic necrosis (IPN). A “two layer” indirect FAT allowed demonstration of the respective viruses in cell cultures and a “three layer” indirect FAT allowed demonstration of trout antibody to the viruses. Antibody, by means of the latter technique, could be demonstrated only in artificially immunized trout.     

Seriousness and stability of subclinical mastitis assessed by quarter milk serum albumin

Bovine Serum Albumin (BSA) concentration in quarter milk samples from 51 cows examined twice, at 1½ months intervals, was related to subclinical mastitis diagnoses and to the change in diagnoses from the first to the second examination. The BSA-concentration increased with increasing scores of the California Mastitis Test (CMT). The concentration of BSA was higher if bacteria were isolated as compared to negative bacteriological findings, and it was higher if “major pathogens” (MaP) (Staphylococcus aureus or Streptococcus dysgalactiae) rather than “minor pathogens” (MiP) (S. epidermidis or α-streptococci) were isolated. There was no interaction in the “effects” of CMT-score and bacteria on BSA-concentration. Quarters which were healthy and pathogenfree at first examination and had a non-specific mastitis at the subsequent examination, had significantly higher BSA-concentration at first examination than those which remained healthy. Quarters with non-specific mastitis at the first examination and infectious mastitis at the next examination had higher BSA-concentration at the first examinition than those which turned out with other diagnoses. Quarters with infectious mastitis and MaP at first examination which had a latent infection at the next testing, had a lower BSA-concentration than those with other second examination diagnosis. In general, BSA seems to be a more sensitive parameter than CMT for showing the early establishment of an inflammatory reaction in the alveolar tissue.     

A stochastic model simulating milk fever in a dairy herd

A simulation model was developed to evaluate the long-term effect of control strategies against milk fever (MF); here, we present the base model and sensitivity analyses. The representation of the within-herd dynamics was based on the existing SimHerd II model. Because of the relationships between MF and other diseases, the new model (called “SimHerd III”) includes diseases common in a dairy herd.

The cow level risk factors modelled were: base risk in the herd, parity, milk-yield potential, lactational disease recurrence, disease interrelationships, body condition and season. The diseases include clinical cases of MF, dystocia, downer-cow syndrome, retained placenta, metritis, displaced abomasum, ketosis and mastitis. The effects of diseases were represented by daily milk yield, daily body weight, daily feed intake, risk of stillbirth, conception probability, decision on culling, death and immediate removal. Simulated technical results showed that the herd effects of reduced risk of MF differed according to the reproductive efficiency in the herd. These interactions between reproduction efficiency and the effect of reduced base risk of MF were related to differences in how the simulated herds reacted to the reduction in replacements caused by MF.

In the sensitivity analysis, eight potential key parameters were changed to their lowest and highest expected values retrieved from the literature. When measuring the sensitivity on milk production in the herd (as the economically most important technical effect), the model seemed most sensitive to the uncertainty of effect of MF on death risk and MF-recurrence risk.     

Advancements in sensor technology and decision support intelligent tools to assist smart livestock farming

Remote monitoring, modern data collection through sensors, rapid data transfer, and vast data storage through the Internet of Things (IoT) have advanced precision livestock farming (PLF) in the last 20 yr. PLF is relevant to many fields of livestock production, including aerial- and satellite-based measurement of pasture’s forage quantity and quality; body weight and composition and physiological assessments; on-animal devices to monitor location, activity, and behaviors in grazing and foraging environments; early detection of lameness and other diseases; milk yield and composition; reproductive measurements and calving diseases; and feed intake and greenhouse gas emissions, to name just a few. There are many possibilities to improve animal production through PLF, but the combination of PLF and computer modeling is necessary to facilitate on-farm applicability. Concept- or knowledge-driven (mechanistic) models are established on scientific knowledge, and they are based on the conceptualization of hypotheses about variable interrelationships. Artificial intelligence (AI), on the other hand, is a data-driven approach that can manipulate and represent the big data accumulated by sensors and IoT. Still, it cannot explicitly explain the underlying assumptions of the intrinsic relationships in the data core because it lacks the wisdom that confers understanding and principles. The lack of wisdom in AI is because everything revolves around numbers. The associations among the numbers are obtained through the “automatized” learning process of mathematical correlations and covariances, not through “human causation” and abstract conceptualization of physiological or production principles. AI starts with comparative analogies to establish concepts and provides memory for future comparisons. Then, the learning process evolves from seeking wisdom through the systematic use of reasoning. AI is a relatively novel concept in many science fields. It may well be “the missing link” to expedite the transition of the traditional maximizing output mentality to a more mindful purpose of optimizing production efficiency while alleviating resource allocation for production. The integration between concept- and data-driven modeling through parallel hybridization of mechanistic and AI models will yield a hybrid intelligent mechanistic model that, along with data collection through PLF, is paramount to transcend the current status of livestock production in achieving sustainability.     

Bisection of post-compaction bovine embryos: the difference in viability between the two monozygotic halves

Bisection of bovine post-compaction embryos has become a useful tool for improving embryo transfer results. Compared to pre-compaction division, the technique is simpler but is does involve some cellular damage and rarely provides two completely identical “halves”. Monozygotic pairs can therefore be divided into “good” and “poor” half embryos. By 4–6 h of culture in vitro, “good” halves remained significantly more viable than their poorer counterparts. Gytological evaluation after 24 h culture shows that the morphologically better halves contain more cells (an average of 45.9 vs 23.0) and have a higher mitotic index (6.1 % vs 3.1 %) than the poorer halves. The single transfer of 26 half-embryos resulted in 15 pregnancies (55.6 %) but no difference could be demonstrated between the results obtained with halves of different sizes. Nevertheless, the in vitro results support the contention that bigger halves give better results and also demonstrate that one half-embryo cannot be used as a control for the other in viability studies.     

Tissue culture studies in bovine leukosis

By examining cover slips stained at regular intervals the development of primary lymph node tissue cultures from 2 cases of juvenile bovine leukosis and 2 “normal” foetuses was studied. Secondly, comparisons were made between cell lines prepared from 23 bovines — “normal” animals and foetuses, cases of adult leukosis, juvenile leukosis and skin leukosis — with respect to susceptibility to infection with interferon sensitive viruses (VSV and PRV) and/or growth rate in the presence of sera from “normal” and leukotic animals.Nuclear budding, nuclear fragmentation, lymphocyte adsorption and giant cell formation were observed — though to a much greater extent in cultures prepared from the leukosis animals — in all 4 cases studied. No indications of different susceptibility for the test virus infections appeared between cell lines prepared from “normal” and leukotic animals. The growth rate of the cell lines seemed similar irrespective of the kind of serum used.     

遮阴对大豆幼苗光合和荧光特性的影响

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(P_n)、最大光化学效率(F_v/F_m)、PSⅡ实际光化学效率(Φ_PSⅡ)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。     

Liquoid-induced disseminated intravascular coagulation in the blue fox

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.     

Ultrastructural changes in hereditary muscular hypertrophy in cattle.

Biopsies of skeletal muscle collected from 24 animals classified as “double muscled” were examined by light and electron microscopy. The muscle samples exhibited degenerative changes including the presence of vacuolations and lamellated structures, fragmentation of myofibers, accumulation of glycogen granules, disruption of neuromuscular junctions and disorganization of the sarcolemma. In the light of the excessive fragility of the erythrocyte membranes noted previously, the alteration in the sarcolemma suggests that a generalized cell membrane defect may be the most consistent feature of the “double muscling syndrome” in cattle.     

Effect of extruded linseed on productive and reproductive performance of lactating dairy cows

A total of 356 early lactation multiparous Holstein cows were used in a randomized complete block design to determine the effects of feeding extruded linseed on milk production and composition, and reproductive performance. Forty of these cows were randomly selected to study the effects of extruded linseed on milk fatty acid (FA) profile, individual feed intake and prostaglandin secretion. Cows were fed a 40:60 forage to concentrate ratio diet (17.9% CP, 27.7% NDF and 6.0% EE) ad libitum that was similar in composition between treatments except for the protein supplements that differed and were control (CTR: 4.9% extruded soybean) and linseed (LIN: 5.5% extruded linseed). Individual DM intake measured at 40 (23.0 kg/d) and 90 (24.2 kg/d) days in milk, and milk yield (45.0 kg/d) were not affected by treatment, but the lower (P < 0.05) milk fat percentage in cows fed LIN (2.65%) compared with CTR (2.86%) resulted in lower (P < 0.05) 4.0% fat-corrected milk yield for cows fed LIN (35.4 kg/d) compared with CTR (37.7 kg/d). Milk protein content was higher (P < 0.05) in LIN (3.04%) than in CTR (3.00%). The concentration of saturated FA was lower (P < 0.05) in milk fat from LIN (56.2%) compared with CTR (60.2%). Monounsaturated FA (35.7 vs. 32.7%) and polyunsaturated FA (8.0 vs. 6.9%) were higher in LIN (P < 0.05) than in CTR. Supplementation with LIN also increased (P < 0.05) the proportion of vaccenic acid (2.21 vs. 1.55%), total conjugated linoleic acid (0.91 vs. 0.72%) and n-3 FA (1.21 vs. 0.54%) in milk compared with CTR. Plasma concentrations of prostaglandin metabolite were numerically lower in LIN (106 pg/ml) compared with CTR (120 pg/ml) (P = 0.16) but reproductive performance was similar between treatments. In summary, extruded linseed reduced milk fat percentage and 4.0% fat-corrected milk yield and increased milk protein percentage and the content of healthy FA in milk without modifying DM intake, milk yield and reproductive performance.