Effects of dry cow intramammary therapy on quarter infections in the dry period

Quarter milk samples were taken from 150 cows from three dairy farms in south-east Queensland at drying off, two, four and six weeks after drying off, at calving, and one, two and three weeks after calving. In each of the herds, the cows were randomly allocated to three groups of approximately equal size. One group had all the quarters of all the cows treated at drying off with a dry cow antibiotic infusion containing cloxacillin; the second group was given no treatment, and the third group had selected quarters treated on the basis of their high activity of N-acetyl-beta-D-glucosaminidase at drying off. Dry cow treatment resulted in a marked reduction in the number of infected quarters at two and four weeks after drying off, so that the comprehensively treated group had significantly less infected quarters at these times (P<0.02). Twelve dinical cases of mastitis were detected two weeks after drying off in the untreated groups, 10 in the untreated quarters of the selectively treated groups, and no cases in the comprehensively treated groups. These cases were due mainly to Streptococcus uberis and Streptococcus dysgalactiae. The number of infected untreated quarters increased markedly between drying off and two weeks later, but in all three groups there was a marked decrease in the number of infected quarters between six weeks after drying off and calving, suggesting that the mammary glands were more able to overcome infections at this time.     

Experimental intramammary infection of the dairy cow with Escherichia coli during the nonlactating period

The nonlactating mammary gland was experimentally inoculated with Escherichia coli. During the first half of the nonlactating period, 32% of 34 inoculated glands were temporarily infected. All intramammary infections were eradicated by the cow without therapy and no signs of mastitis were observed. During the 30 days before parturition occurred, 88% of 42 inoculated glands in the cows became infected. Twenty-three intramammary infections were eradicated by the cow and infection in 14 glands persisted after parturition occurred. Peracute toxic mastitis occurred in those cows with infected glands.     

Incidence of intramammary infections during the dry period without or with antibiotic treatment in dairy cows--a quantitative analysis of published data

The study was aimed at summarising the literature that compares the incidence levels of spontaneously occurring intramammary infections (IMI) during the dry period, without versus with antibiotic dry cow treatment (DCT). A meta-analytic relative risk (RR) calculation was implemented when a priori relevant. Two main categories of comparison were used in the 36 selected papers. In the first category, the udder quarters were randomly allocated (at quarter or cow level) to an untreated or a treated group. Quarter incidence averaged 12.8% (weighted mean) in untreated quarters, and depending on the DCT used, from 6.6 to 8.0% in treated quarters. The meta-analytic RR of new IMI for untreated versus treated quarters varied from 1.54 to 1.94, depending on the DCT used. DCT was mainly found effective against IMI due to streptococci and coagulase-positive staphylococci. Based on only a few papers, the application of an internal teat sealer was associated to a quite similar (or possibly better) protection against IMI than DCT, but only in a subpopulation of particular (selected) cows. In the second category of studies, a selective dry cow or quarter antibiotic-treatment (selective DCT or DQT), according to cow or quarter selection criteria, was compared to blanket DCT. The meta-analytic RR of new IMI was 1.71 for selective DCT versus blanket DCT. Selective DQT seemed to be more at risk than selective DCT, but consisted of treating a much lower proportion of quarters. The summary-results provided by our meta-analysis should only be used with caution, due to possibly low external validity. More research seems to be relevant on the risk factors of new IMI during the dry period to make the outcomes of omission of DCT in selected cows more predictable under field conditions.     

Impact of intramammary tilmicosin infusion as a dry cow therapy

Three hundred subclinically infected quarters of 259 Holstein cows infected with gram‐positive bacteria were selected via quota sampling based on the California Mastitis Test (CMT) result and were divided randomly and equally into treatment and test groups. Quarters of test group (n = 150 in 128 cows) were treated with an intramammary infusion of tilmicosin, and quarters of the control group (n = 150 in 131 cows) were treated with cloxacillin as a traditional intramammary infusion of dry cow (DC) ointment. Cows with more than one infected quarter were randomly assigned to the same group, and adjacent quarters were treated the same. The milk samples of all quarters were obtained, and bacterial cultures and somatic cell count (SCC) were tested before dry cow therapy (DCT) (50 ± 15 days before parturition), and finally on day 2 of the next lactation. Results have shown that total bacteriological cure rates on day 2 of the next lactation were 45% and 78%, (p = .01), new infection rates were 43.3% and 56.6%, and SCC was (6.732 × 10⁵ ± 3.124 × 10⁵) and (5.025 × 10⁵ ± 2.935 × 10⁵), (p > .05) in test and control groups, respectively. Tilmicosin had less effect on reducing IMI due to Corynebacterium bovis, and had no effect on Streptococcus agalactiae, but had a potent effect against Staphylococcus aureus. It was concluded that tilmicosin alone should not be infused as an alternative to conventional dry cow therapy. However, it had a significant effect against S. aureus, and the potential of tilmicosin to treat S. aureus IMI should be confirmed in further studies.     

头孢洛宁乳房注入剂防治干乳期奶牛乳腺炎的药效学研究

为了探讨头孢洛宁乳房注入剂对干乳期乳腺炎的防治作用,本研究采用微量稀释法测定比较了头孢洛宁、头孢匹林、阿莫西林和氯唑西林对乳腺炎病原菌(大肠杆菌、金黄色葡萄球菌、乳房链球菌、停乳链球菌、无乳链球菌)的体外抗菌活性;并且,随机选择60头进入干乳期的临床健康奶牛,在最后一次挤奶后每头牛的每个乳区分别灌注一管受试药物或对照药物(氨苄西林-苄星氯唑西林乳房注入剂)。对入选的每头奶牛分别在干奶前、以及产后1、3、5 d,采集每个乳区的乳样进行体细胞计数和细菌学检查。在药物处理后至产后14 d内,每天对受试动物进行临床型乳腺炎检查。结果显示,头孢洛宁、头孢匹林、阿莫西林、氯唑西林对分离自奶牛乳腺炎的大肠杆菌MIC_(50)分别为4、8、8μg/mL128μg/mL;对金黄色葡萄球菌的MIC_(50)分别为0.125、0.25、2、1μg/mL;对乳房链球菌的MIC_(50)分别为4、8、16、128μg/mL;对停乳链球菌的MIC_(50)分别为8、8、8、128μg/mL;对无乳链球菌MIC_(50)分别为0.25、4、0.25、32μg/mL。临床药学研究显示,头孢洛宁乳房注入剂对干乳期奶牛乳腺炎具有良好的防治效果,对不同细菌感染治愈率介于66.6%～100%之间,新感染发生率低于8.3%。在治愈率、新感染率及细菌学清除率方面和对照药物(氨苄西林-苄星氯唑西林乳房注入剂)相比均无显著性差异。表明头孢洛宁对引起奶牛乳腺炎的主要病原菌均具有良好的抗菌活性,干乳期奶牛每乳区灌注一管250 mg的头孢洛宁干乳期乳房注入剂能有效治疗干乳期隐性乳腺炎和预防新的乳腺炎感染。     

Biochemical markers of bone turnover in the dairy cow during lactation and the dry period

We measured a bone-formation marker recognizing osteocalcin, and a bone-resorption marker recognizing C-telopeptide (CT(x)) fragments of collagen type I, in a longitudinal study. The levels of these markers in the plasma of dairy cows (n=11) were recorded over a 12 month postpartum period, including a full lactation and a dry period. The plasma concentration of CT(x) was highest in the first week after parturition. It then declined slowly over the next 33 weeks and remained low until the next parturition. Osteocalcin concentration was lowest around parturition, reached a plateau during mid-lactation, then fell again towards term. There were large variations in bone metabolism during a lactation, that were not directly related to milk production. These results may be used to facilitate appropriate adjustments to calcium and phosphorous concentrations in the diet, reflecting the specific needs of each stage of the reproductive cycle.     

Quarter,cow, and farm risk factors for intramammary infections with major pathogens relative to minor pathogens in Thai dairy cows

A cross-sectional study was carried out from May to September 2011 on 35 smallholder dairy farms in Chiang Mai, Thailand, to identify the quarter, cow, and farm factors that relate to intramammary infections (IMI) from major specified pathogens, compared to infections from minor pathogens. Data on general farm management, milking management, and dry cow management were recorded for each herd. Quarter milk samples were collected from either clinical or subclinical mastitis quarters. Dependent variables were binary data defining the specified major pathogens, including Streptococcus agalactiae (7.1 %), Streptococcus uberis (9.4 %), Streptococcus dysgalactiae (4.0 %), and other streptococci (16.7 %), as a case, and all minor pathogens as a control, in each dependent variable. The occurrence of S. agalactiae IMI was lower in first-parity cows and cows with short milking time. Cows with body condition score (BCS) <2.5 had higher occurrence of S. agalactiae IMI. The occurrence of S. uberis IMI was higher in quarters with California mastitis test (CMT) score 2, score 3, and having clinical mastitis and in farms with increasing age of vacuum system. Quarters with CMT score 3, having clinical mastitis, cow with manual milking after detaching milking cluster, and farms with high bulk milk somatic cell counts (BMSCC >500,000 cells/ml) had higher occurrence of S. dysgalactiae IMI. For other streptococci, quarters having clinical mastitis, BCS <2.5, and pulling down of milking cluster while milking increased occurrence of other streptococci IMI relative to minor pathogen IMI. These results highlight the importance of individual cow factors, milking characteristics, and BMSCC in determining the risk of IMI from major pathogens.     

Local and systemic immune response in the cow after intramammary vaccination during lactation

The local and systemic immune response of the lactating cow during the 10 week period after intramammary (IMM) vaccination with killed Mycobacterium bovis (M. bovis) was evaluated. Antigen (tuberculin)-reactive lymphocytes were present in the milk as early as 2 weeks post-vaccination, and in the blood at 6 weeks after vaccination. The milk lymphocytes, compared to the blood lymphocytes were consistently more responsive to tuberculin. Both blood and milk lymphocytes responded in vitro to the lectins, phytohemagglutinin-A (PHA-P) and concanavalin A (Con A), although the milk lymphocytes were consistently less responsive than the blood lymphocytes during the period. Anti-tuberculin antibody was significantly elevated in the milk and blood of the vaccinated animals at 10 weeks post-vaccination. Infusion of tuberculin into the mammary glands of the cows 10 weeks after vaccination resulted in a marked increase in the number of milk leukocytes. The influx of leukocytes initially consisted of polymorphonuclear leukocytes (PMNL), and later, mononuclear leukocytes. Intramammary vaccination also resulted in antigen recognition at sites distant from the mammary gland.     

Radiographic method for anatomic study of the teat canal: characteristics related to resistance to new intramammary infection during lactation and the early dry period.

An in vivo radiographic method to determine teat canal anatomy has shown that resistant quarters had teat canals with a smaller diameter than that of susceptible quarters. The length of the teat canal did not appear to be related to resistance to new intramammary infections. These findings relate to new infection caused by Aerobacter aerogenes, Streptococcus agalactiae, and Staphylococcus aureus. Quarters guarded by teat canals with larger diameter were less resistent to new infection during both lactation and the early dry period compared with quarters guarded by teat canals with small diameter.     

Frequency of isolation of environmental mastitis-causing pathogens and incidence of new intramammary infection during the nonlactating period

Quarter samples (n = 6,328) of mammary secretions were collected from 160 cows during physiologic transitions of the udder to determine the frequency of isolation of mastitis-causing pathogens and the incidence of new intramammary infections (IMI) during the nonlactating period. None of the cows in the herd was infected with Streptococcus agalactiae, and the prevalence of Staphylococcus aureus was low. Cows were not treated with antibiotics at cessation of milking. A threefold increase in the percentage of quarters infected with major mastitis-causing pathogens developed from late lactation to early involution. Coliforms and streptococci other than Str agalactiae accounted for 94% of major pathogen infections. The number of quarters infected with coagulase-negative staphylococci increased slightly from late lactation to early involution, whereas the number of quarters infected with Corynebacterium bovis decreased markedly. Major pathogens caused 101 of 153 IMI at parturition and greater than 90% were caused by streptococci and coliforms. At parturition, 51 of 52 minor pathogen IMI were caused by coagulase-negative staphylococci. During early lactation, there was a marked decrease in quarters infected with major pathogens; however, the number of quarters with major pathogen IMI during early lactation was 2.3 times higher than the number of quarters infected before cessation of milking. The number of quarters with minor pathogen IMI during early lactation was the same as at parturition, but a marked decrease in quarters infected with coagulase-negative staphylococci and a marked increase in C bovis IMI developed from parturition to early lactation.     

Herd-level risk factors for Staphylococcus aureus and Streptococcus agalactiae intramammary infections

Herd-level risk factors for high herd prevalence of Staphylococcus aureus and Streptococcus agalactiae intramammary infection were studied using data from Holstein herds participating in the New York State Quality Milk Promotion Services Program during the period 1978–1983. Using information from initial surveys and bacteriologic sampling of all herds, a set of possible risk factors for each organism was examined. Comparisons between herds with high and zero prevalence of each infection were made. Failure to teat dip and use of common cloths or sponges for udder preparation increased the odds of high prevalence for both organisms. Selective or no dry cow therapy, having tie stall or stanchion housing and using dry massage or no udder preparation increased the risk for Str. agalactiae, but not for S. aureus infection. Milking machine function played a role in the risk of both infections.     

Risk factors for intramammary infections and relationship with somatic-cell counts in Italian dairy goats

Routine examination of milk was performed on five herds of lactating goats in northern Italy as part of a milk quality-monitoring program in the year 2000. As part of the study, aseptic samples of foremilk were collected monthly from both half udders during the entire lactation for 305 goats, resulting in a total of 4571 samples. The samples were tested with cytological and bacteriological analyses to evaluate the relationship between mammary infections and somatic-cell count (SCC; Fossomatic (TM) method). Prevalence of intramammary infection (IMI) was 40.2% (n = 1837) of all udder-half samples examined. The most-prevalent mastitis agents were coagulase-negative Staphylococci (CNS), 80% (n = 1474 udder-half samples); within this group, Staphylococcus epidermidis was the most-prevalent species (38%). Other prevalence were Staphylococcus aureus 6% (n = 112 udder-half samples) and environmental pathogens 14% of infected udder-half samples (n = 251) with a diverse mixture of species, none of which had a frequency of >4%. Enterococcus faecalis was the most-frequently isolated among this group. Neither Salmonella spp. nor Listeria monocytogenes were detected. The risk (sample level) of infection differed across herds, parities, and stage of lactation according to results from logistic multiple regression. Infection was more common among goats in third and fourth parities and during the later stages of lactation. Of the 2734 samples from uninfected udder halves, the mean log₂ SCC was 3.9 cell/ml; of the 1837 bacteriological positive samples, the mean log₂ SCC was 5.6 cell/ml. According to results from a linear mixed model, concentrations of somatic cells tended to increase with increasing age and days in milk and with the presence of bacteria. Infection with S. aureus was associated with the highest SCS.     

如何使奶牛安全健康地度过干奶期

干奶期是指在奶牛产犊前的某一段时间(一般在产犊前75~45d),通过一定的方法,人为的强制奶牛停止产奶。干奶过程一般持续3~7d左右。干奶完成后,奶牛进入干奶期。这个阶段大约维持50~60d左右。一般从开始干奶至产犊的整个阶段统称为干奶期。干奶期的意义很重大,主要有:(1)干奶期是胚胎发育的需要:干乳母牛是妊娠后期的母牛,胎儿增重量加大,需要较多营养供胎儿发育,实行干乳期停乳,有利胎儿的发育。(2)干奶期是乳腺的恢复、增殖、更新的需要:奶牛,特别是高产奶牛,泌乳期乳腺组织大量损失,所以泌乳器官应有一个休息的时间。产犊前乳腺的生长使萎…