Genetic analysis for mastitis resistance and milk somatic cell score in French Lacaune dairy sheep

Genetic analysis for mastitis resistance was studied from two data sets. Firstly, risk factors for different mastitis traits, i.e. culling due to clinical or chronic mastitis and subclinical mastitis predicted from somatic cell count (SCC), were explored using data from 957 first lactation Lacaune ewes of an experimental INRA flock composed of two divergent lines for milk yield. Secondly, genetic parameters for SCC were estimated from 5 272 first lactation Lacaune ewes recorded among 38 flocks, using an animal model. In the experimental flock, the frequency of culling due to clinical mastitis (5%) was lower than that of subclinical mastitis (10%) predicted from SCC. Predicted subclinical mastitis was unfavourably associated with the milk yield level. Such an antagonism was not detected for clinical mastitis, which could result, to some extent, from its low frequency or from the limited amount of data. In practice, however, selection for mastitis resistance could be limited in a first approach to selection against subclinical mastitis using SCC. The heritability estimate of SCC was 0.15 for the lactation mean trait and varied from 0.04 to 0.12 from the first to the fifth test-day. The genetic correlation between lactation SCC and milk yield was slightly positive (0.15) but showed a strong evolution during lactation, i.e. from favourable (-0.48) to antagonistic (0.27). On a lactation basis, our results suggest that selection for mastitis resistance based on SCC is feasible. Patterns for genetic parameters within first lactation, however, require further confirmation and investigation.     

The pathogenesis and control of Staphylococcus aureus-induced mastitis: study models in the mouse

The intramammary colonisation by Staphylococcus aureus provokes mastitis in the cow. Once established, the infection is difficult to eradicate with available therapies and may become chronic. The present article focuses on the use of the experimental mouse model of S. aureus-induced mastitis as a practical approach for the study of bovine mastitis. Results obtained regarding the pathogenesis of S. aureus and the development of new therapeutic approaches are discussed.     

Summer mastitis experimentally induced by Hydrotaea irritans exposed to bacteria

Abstract. Summer mastitis is an acute suppurative bacterial infection of the udder in heifers and dry cows. To ascertain the possible role of flies in the transmission of the disease, experimental exposures of recipient heifers to Hydrotaea irritans previously exposed to bacteria were carried out. Flies were allowed to feed on secretions from clinical cases of summer mastitis. The pathogens present were the bacteria Staphylococcus aureus, Streptococcus dysgalactiae, Actinomyces pyogenes , Stuart-Schwan cocci, Peptococcus indolicus, Fusobacterium necrophorum and Bacterioides species. The teats of eight heifers were exposed to flies with verified pathogen content. Two teats of each animal were deliberately damaged before fly exposure. One teat was cut, another pricked with insect needles to mimic insect bites. Two of the heifers developed summer mastitis in the quarters where teats had been cut. The bacterial species isolated from these quarters corresponded to those that had previously been fed to the flies. For the first time, it is now demonstrated that H.irritans is capable of transmitting summer mastitis pathogens and so causing summer mastitis in recipient heifers. Lesions on the teat orifice may be a predisposing factor in the development of the disease.     

A histological study of the effects of enzootic abortion of ewes virus in the lactating bovine mammary gland

Inoculation of the udders of cows with the virus of enzootic abortion of ewes resulted in a severe acute mastitis. The mastitis was characterized clinically by pyrexia, anorexia, decreased milk production, swelling and marked alteration in the physical quality of the milk. The basic lesion was necrosis of alveolar and duct epithelial cells. Virus particles were demonstrated in all levels of the mammary gland three days after inoculation illustrating the rapid spread of the agent. Cells resembling Reed-Sternberg cells and similar to those seen in experimental mastitis produced by the virus of infectious bovine rhinotracheitis were seen in tissues collected six and nine days after inoculation.     

Ocular development and involution in the European cave salamander, Proteus anguinus laurenti.

The anatomy and development of the eye of Proteus anguinus are described. The relationships between organogenesis of the eye in embryos and larva and its involution in the young and the adult are discussed. The availability (in breeding cultures) of a significant number of Proteus embryos (which are normally rare) allowed experimental analysis of the effects of light, xenoplastic differentiation and thyroid hormones on the development of the eye. The results of this study suggest that development and involution of the eye of Proteus are controlled by genetic factors which are not greatly influenced by environment, and one can, therefore, consider the microphthalmy of Proteus as a relict characteristic which is the result of a specific development with disturbance of the normal ontogenic process.     

复方蛇床子灌注液对奶牛乳房炎6种主要致病菌的抑杀作用

目的通过实验证明复方蛇床子灌注液对奶牛乳房炎病原菌的抑杀作用。方法复方蛇床子灌注液为受试药物,6种引起奶牛乳房炎的常见病原菌（金黄色葡萄球菌、大肠埃希菌、无乳链球菌、停乳链球菌、白色念珠菌和热带假丝酵母菌）为实验菌株,采用测定抑菌圈的琼脂平板扩散法和测定最小抑菌浓度（M IC）的药物固体培养基法来评价复方蛇床子灌注液的体外抗菌活性。结果复方蛇床子灌注液对6种供试菌株均有较好的抑菌作用,其中0.1 g/mL的原药液对无乳链球菌和金黄色葡萄球菌表现了强大的抑制作用（M IC值达0.0015 g/mL）,抑菌圈直径分别高达33 mm和28 mm。结论复方蛇床子灌注液对奶牛乳房炎6种主要致病菌有较强的抑杀作用,抗菌谱广,药物浓度与抑菌效应呈正相关。     

Studies on the possible role of cattle nuisance flies, especially Hydrotaea irritans, in the transmission of summer mastitis in Denmark

The summer mastitis pathogens Actinomyces pyogenes, Peptococcus indolicus, Bacteroides melaninogenicus ss. levii, Fusobacterium necrophorum and Streptococcus dysgalactiae were isolated from the polyphagous symbovine dipterans Hydrotaea irritans (Fallén) and Morellia sp. caught around dairy heifers on pasture, but not from the haematophagous species Haematobia irritans (L.), Haematobosca stimulans (Meigen), Culicoides sp. and Simulium sp. Secretions from clinical cases of summer mastitis proved to be sources of summer mastitis bacteria for more than 3 weeks despite antibiotic treatment and teat amputation. Taking into account the seasonal activity pattern of Hydrotaea irritans and its topographical distribution on grazing cattle, it appears evident that this fly may play a central role in the establishment and maintenance of the bacterial contamination with summer mastitis pathogens on the teats of healthy cattle. In the present study the survival of A.pyogenes and P.indolicus for 7 days in experimentally infected Hydrotaea irritans, as demonstrated by the recovery of these microorganisms from agar plates exposed to live infected flies, is described. However, experimental transmission of summer mastitis from sick to healthy heifers by Hydrotaea irritans proved unsuccessful.     

Short communication: Variance and autocorrelation of deviations in daily milk yield are related with clinical mastitis in dairy cows

Daily milk production, and fluctuations therein, can provide information on health and resilience of dairy cows. We studied variance and autocorrelation of deviations in daily milk yield in relation to the occurrence of clinical mastitis (no, early or later in lactation). Individual lactation curves were fitted to 305-d lactations of 414 dairy cows using quantile regression. Log-transformed variance (lnVar) and autocorrelation of the quantile residuals of daily milk yield (predicted – observed) were evaluated for intervals until 30 and until 305 days in milk (DIM). Cows were classified as having no mastitis (n = 249), early mastitis that first occurred before 30 DIM (n = 29); or later mastitis (n = 136). Subsequently, linear models were used to assess effects of mastitis and parity class (primiparous or multiparous) on lnVar and autocorrelations; and logistic regression analyses were performed to predict mastitis from lnVar or autocorrelation and parity. From 10 to 30 DIM, lnVar was greater for cows with early mastitis than for cows with no or late mastitis, and autocorrelation tended to be lower for cows with early mastitis than for cows with no mastitis. The lnVar and autocorrelation from 10 to 30 DIM were not predictive of late mastitis. From 10 to 305 DIM, lnVar was greater and autocorrelation was lower for both cows with early and late mastitis than for cows with no mastitis; and both were predictive of having mastitis in the 305-d lactation. Primiparous cows had lower lnVar than multiparous cows. In cows without mastitis, autocorrelation values were positively correlated with lnVar. Results confirm that increased lnVar is associated with clinical mastitis.     

Lethal effect of polymyxin B sulfate in experimental Proteus rettgeri infection in mice

The mouse model of intraperitoneal sepsis with Proteus rettgeri was used to evaluate the anti-endotoxic effect of polymyxin B sulfate. An unexpected reversal of the usual protective effect of polymyxin in experimental enterobacterial sepsis was observed in which the lethality of the infection was enhanced.     

Beta-lactamase activity of bacteria of the genus Proteus]

beta-Lactamases of Proteus and their role in the mechanism of the microbe resistance to penicillins and ceporin were studied. It was found that the beta-lactamase of Proteus had low activity and were produced by both beta-lactamide resistant and sensitive clinical strains of Proteus. The resistant cultures of Proteus produced enzymes more frequently (3.4--5 times) than the sensitive ones. The synthesis of beta-lactamase in the clinical Proteus strains was inducable. The high induction coefficient was achieved only in the presence of high concentrations of the inductor. No significant dependence of the culture sensitivity level of ampicillin and ceporin on the induction level was observed. The most significant part of the constitutive enzyme in Proteus was intracellular, while that of the inducable enzyme was extracellular. No correlative dependence between the culture resistance levels to penicillins and ceporin and the enzyme activity was noted. The beta-lactamase activity was not found in the transconjugants with the in vitro acquired R-factor controlling the ampicillin and ceporin resistance, as well as in the resistant mutants selected on the media with increasing concentrations of the above antibiotics. Induction of beta-lactamase synthesis was not found in these strains either. The ability of Proteus to synthesize beta-lactamase can be lost on the strain storage under laboratory conditions which was not always accompanied by reduction of the culture sensitivity to ampicillin and ceporin. The enzymatic destruction of beta-lactamides was not the main mechanism of Proteus resistance to the above antibiotics.     

Genome sequences of two Staphylococcus aureus ovine strains that induce severe (strain O11) and mild (strain O46) mastitis

Staphylococcus aureus is a major etiological agent of mastitis in ruminants. We report here the genome sequences of two ovine strains that were isolated from gangrenous (strain O11) and subclinical (strain O46) ewe mastitis. Both strains belong to the same clonal complex. Despite this close genotypic relationship, the two isolates were shown to reproducibly induce highly divergent types of infections, either severe (O11) or mild (O46) mastitis, in an experimental ewe model.     

Milk Antitrypsin Activity During Clinical and Experimental Bovine Mastitis

Milk trypsin-inhibitor levels were followed during clinical and experimental endotoxin-induced mastitis. Milk trypsin-inhibitor level proved to be a good indicator of mastitis, closely relating to milk BSA values. The trypsin-inhibitor pattern in the quarter milk samples during mastitis closely resembled the pattern of BSA, which indicates that the trypsin-inhibitor is blood derived and diffuses to the mammary gland lite albumin. The timing of the increase in the trypsin-inhibitor into the endotoxin infused quarter closely matched with the increase in body temperature, heart rate, decrease in blood leucocytes and increase in somatic cells. Serum zinc and iron showed a decrease a few hours later.     

Association of the M blood group system with bovine mastitis

Associations of the 11 bovine blood group systems with mastitis were examined in Red Danish dairy cattle. The mastitis status was followed during three lactational periods. A significant effect of the M blood group system on mastitis incidence was observed in the first and second lactation periods and a lower frequency of mastitis is found among animals lacking the M' factor as compared to those having the M' blood group factor. The significance of these results are discussed in view of the close relation between the M blood group system and the bovine lymphocyte antigens (BoLA), and the expected effect of eliminating the M' gene from the breed is estimated. Among the remaining 10 blood group systems, the T' system was the only system showing an overall effect on mastitis, and only in first and third lactation. However, the T' system was inconsistent with regard to the effect of the T' gene on the various mastitis diagnoses.     

Identification and analysis of putative promoter motifs in bovine herpes virus

The purpose of this study is to identify and analyse the putative promoter motifs in the bovine herpes virus which causes several diseases in cattle worldwide including bovine mastitis with large economic impact on dairy industry. Bovine mastitis caused due to virus is often neglected as bacterial infections are held mainly responsible for the disease. Therefore, in this in silico investigation with all the existing experimental data a total of 147 promoter were identified along with their sequences from three genome viz bovine herpes virus 1 (BHV), bovine herpes virus 4 and bovine herpes virus 5, out of which 39 promoters were from bovine herpes virus 4 (BHV 4), 95 from BHV1 and 13 from BHV5 and it was observed that BHV1 and BHV5 have a close evolutionary history. However, they belong to the same subfamily and size of the genome and GC% of BHV1 and BHV5 was almost equal and very high compare to that of BHV4. This analysis may help in designing the live attenuated vaccine against BHV causing bovine mastitis that reduces the incidence of bovine mastitis. Identification of promoters may also help in designing of expression vectors which help in better understanding of the regulation of gene expression. In the era of large genomics and proteomics prediction of promoters in the whole genome is crucial for the advancement of drug discovery and gene therapy.     

Economic consequences of mastitis and withdrawal of milk with high somatic cell count in Swedish dairy herds

The main aim was to assess the impact of mastitis on technical and economic results of a dairy herd under current Swedish farming conditions. The second aim was to investigate the effects obtained by withdrawing milk with high somatic cell count (SCC). A dynamic and stochastic simulation model, SimHerd, was used to study the effects of mastitis in a herd with 150 cows. Results given the initial incidence of mastitis (32 and 33 clinical and subclinical cases per 100 cow-years, respectively) were studied, together with the consequences of reducing or increasing the incidence of mastitis by 50%, modelling no clinical mastitis (CM) while keeping the incidence of subclinical mastitis (SCM) constant and vice versa. Six different strategies to withdraw milk with high SCC were compared. The decision to withdraw milk was based on herd-level information in three scenarios: withdrawal was initiated when the predicted bulk tank SCC exceeded 220 000, 200 000 or 180 000 cells/ml, and on cow-level information in three scenarios: withdrawal was initiated when the predicted SCC in an individual cow's milk exceeded 1 000 000, 750 000 or 500 000 cells/ml. The accuracy with which SCC was measured and predicted was assumed to affect the profitability of withdrawing milk with high SCC and this was investigated by applying high, low or no uncertainty to true SCC. The yearly avoidable cost of mastitis was estimated at €8235, assuming that the initial incidence of mastitis could be reduced by 50%. This cost corresponded to 5% of the herd net return given the initial incidence of mastitis. Expressed per cow-year, the avoidable cost of mastitis was €55. The costs per case of CM and SCM were estimated at €278 and €60, respectively. Withdrawing milk with high SCC was never profitable because this generated a substantial amount of milk withdrawal that was not offset by a sufficient increase in the average price per delivered kg milk. It had the most negative impact on net return when high incidence of mastitis was simulated. Withdrawing milk with high SCC based on low-uncertainty information reduced the amount of withdrawn milk and thus resulted in less negative effect on net return. It was concluded that the current milk-pricing system makes it more profitable for farmers to sell a larger amount of milk with higher SCC than to withdraw milk with high SCC to obtain payment premiums, at least in herds with mastitis incidences within the simulated ranges.     

Association of the M blood group system with bovine mastitis*

Associations of the 11 bovine blood group systems with mastitis were examined in Red Danish dairy cattle. The mastitis status was followed during three lactational periods. A significant effect of the M blood group system on mastitis incidence was observed in the first and second lactation periods and a lower frequency of mastitis is found among animals lacking the M' factor as compared to those having the M' blood group factor. The significance of these results are discussed in view of the close relation between the M blood group system and the bovine lymphocyte antigens (BoLA), and the expected effect of eliminating the M' gene from the breed is estimated. Among the remaining 10 blood group systems, the T' system was the only system showing an overall effect on mastitis, and only in first and third lactation. However, the T' system was inconsistent with regard to the effect of the T' gene on the various mastitis diagnoses.     

Quantitative trait loci for clinical mastitis on chromosomes 2, 6, 14 and 20 in Norwegian Red cattle

Mastitis is the most frequent and costly disease in dairy production and solutions leading to a reduction in the incidence of mastitis are highly demanded. Here a genome-wide association study was performed to identify polymorphisms affecting susceptibility to mastitis. Genotypes for 17 349 SNPs distributed across the 29 bovine autosomal chromosomes from a total of 2589 sires with 1 389 776 daughters with records on clinical mastitis were included in the analysis. Records of occurrence of clinical mastitis were divided into seven time periods in the first three lactations in order to identify quantitative trait loci affecting mastitis susceptibility in particular phases of lactation. The most convincing results from the association mapping were followed up and validated by a combined linkage disequilibrium and linkage analysis. The study revealed quantitative trait loci affecting occurrence of clinical mastitis in the periparturient period on chromosomes 2, 6 and 20 and a quantitative trait locus affecting occurrence of clinical mastitis in late lactation on chromosome 14. None of the quantitative trait loci for clinical mastitis detected in the study seemed to affect lactation average of somatic cell score. The SNPs highly associated with clinical mastitis lie near both the gene encoding interleukin 8 on chromosome 6 and the genes encoding the two interleukin 8 receptors on chromosome 2.     

Serodiagnosis and the immunological aspects of Proteus infection. IV. Serum antibody level and the pathomorphological and bacteriological indices in experimental mixed and monoinfections of the urinary tract

In developing the serodiagnosis of the Proteus infection of the urinary tract experimental hematogenic Proteus or Proteus-Escherichia pyelonephritis was reproduced. In this infection the time course, level and avidity of serum antibodies correlated with the isolation of the causative agents from urine samples used as seed material and with histological changes in the kidneys. The serological tests revealed high titres of H-antibodies and the presence of O-antibodies, while in cases of bacteriuria not accompanied by kidney lesions only H-antibodies in low titers were detected. The results obtained in the study of immune shifts can be used for etiological diagnosis and more exact localization of the pathological process in the urinary system.     

Effect of clinical mastitis and other diseases on reproductive performance of Holstein cows

The objective of this study was to evaluate the effect of clinical mastitis and (or) other diseases on reproductive performance in lactating Holstein cows. Cows (n=967) from a commercial dairy farm were divided into four groups retrospectively: cows with clinical mastitis and other diseases (MD, n=54), clinical mastitis only (M, n=154), other diseases only (D, n=187), and cows with no record of clinical mastitis or other diseases (H, n=572). Days in milk at first service (DIMFS), services per conception (S/C), days not pregnant (DNP), the rate at which animals became pregnant over time and the proportion of cows that remained non-pregnant during 224 days of lactation were evaluated. Groups MD and M had greater (P<0.05) DNP compared with H (155+/-15 and 140+/-5 vs. 88+/-2, respectively). Moreover, MD and M had greater (P<0.05) S/C compared with H (3.0+/-0.4 and 2.1+/-0.1 vs. 1.6+/-0.1, respectively). The rate at which animals became pregnant over time was less (P<0.05) for MD and M and tended (P=0.1) to be less for D when compared with H. In addition, proportion of cows that remained non-pregnant by 224 days of lactation was greater (P<0.05) in MD, M, and D compared with H. Cows with mastitis were also divided into three groups according to the day of occurrence of the first case of clinical mastitis: (1) clinical mastitis occurred before 56 days postpartum (MP1); (2) clinical mastitis occurred between 56 and 105 days after parturition (MP2); and (3) clinical mastitis occurred after 105 days postpartum (MP3) Regardless of the time of occurrence, DNP was greater (P<0.05) for cows with mastitis compared with H. Time of mastitis occurrence affected S/C in that cows in MP2 and MP3 had a greater S/C compared with H cows (P<0.05). Reproductive efficiency was decreased by the presence of clinical mastitis alone because a greater proportion of cows with mastitis remained non-pregnant over time. Moreover, a greater proportion of cows with mastitis or diseases remained non-pregnant by 224 postpartum. Furthermore, the negative effects on reproduction were exacerbated when cows experienced both clinical mastitis and other diseases.     

Endocrine profiles of dairy cows following experimentally induced clinical mastitis during early lactation

Concentrations of LH, cortisol, estradiol-17beta (E(2)), prolactin and 13,14-dihydro-15-keto-prostaglandin F(2alpha) (PGFM) were determined in cows with experimentally induced clinical mastitis during early lactation. Cows free of intramammary infection (IMI) and in the luteal phase of the estrous cycle were balanced by lactation number and days in milk and assigned to either control (n=5) or treatment (n=5) groups. Treated cows were infected experimentally (day 0), in two mammary quarters, with Streptococcus uberis and developed clinical mastitis within 60 h after inoculation as evidenced by increased mastitis scores, elevated rectal temperatures, mammary swelling and isolation of S. uberis pathogen. Four days following bacterial challenge, blood samples were collected every 20 min for 8 h for determination of PGFM and LH following administration of oxytocin and GnRH, respectively. Blood samples were also collected on days 0, 4 and 7 of the experiment to determine concentrations of E(2), prolactin and cortisol. Four days after bacterial challenge, concentrations of cortisol were higher (P=0.04) in experimentally infected cows than controls. Experimentally challenged cows had increased (P=0.02) concentrations of cortisol on days 4 and 7 compared with day 0. Control cows had no significant increase in blood cortisol during the experimental period. Baseline concentrations of PGFM did not differ between groups; however, peak concentrations of PGFM following oxytocin challenge were elevated (P=0.006) in cows with clinical mastitis compared with control animals. Prolactin, E(2) and LH did not differ between cows with clinical mastitis or controls. Experimentally induced mastitis during early lactation elevated concentrations of cortisol during the luteal phase of the estrous cycle. Furthermore, mastitic cows demonstrated an increased PGFM response following oxytocin administration. Altered reproductive efficiency in cows with clinical mastitis caused by Gram-positive pathogens may be the result of increased uterine sensitivity to prostaglandin F(2alpha) (PGF(2alpha)).