Risk Of Mastitis Research Articles

Low Somatic Cell Count: a Risk Factor for Subsequent Clinical Mastitis in a Dairy Herd

A case-control study was conducted to evaluate factors measured at the udder inflammation-free state as risk factors for subsequent clinical mastitis. The factors including somatic cell count (SCC), body condition score, milk yield, percentages of milk fat and milk protein, and diseases were evaluated for their association with the results of udder inflammatory response. The results of the response were specified as presence (case) and absence (control) of clinical signs of mastitis. Data on Holstein Friesian cows calving from January 1984 to November 1996 from a commercial farm with low bulk milk SCC were used. Univariable and multivariable random-effect logistic models were used to evaluate the effect of those factors on the risk of clinical mastitis. The following variables were associated with increased odds of case versus control events in the uni-variable analysis: early lactation period, low SCC, high milk yield, high percentage of milk protein, high percentage of milk fat, low body condition score, retained placenta, and milk fever. For the final multivariable model of all variables used for analysis, only low SCC remained significantly associated with increased risk of subsequent clinical mastitis. The authors concluded that very low SCC during the udder inflammation-free state are associated with increased risk of clinical mastitis.

Relationship of early first lactation somatic cell count with risk of subsequent first clinical mastitis

The relationship between initial Somatic Cell Count (SCC) and time to first clinical mastitis was estimated from data including 20,422 Holstein heifers, without clinical signs of mastitis during the first month of lactation and with a first test day SCC lower than 400,000 cells/ml. Number of days from 35 days after first calving to first clinical mastitis event in first or second lactation was studied using survival analysis methodology, allowing for censored data. The model included the effects of SCC and milk yield at first test, herd-year, calving month, and lactation stage. Separate analyses were also performed for subsets of herds with low or high mastitis frequency and SCC. The risk of first clinical mastitis was highest around the second calving, in lactations starting in summer, and for high-yielding cows. The probability of clinical mastitis occurring increased continuously as initial SCC increased. The same pattern was observed in herds with low or high SCC level. In herds with the lowest mastitis frequencies, relationship between initial SCC and mastitis occurrence was weakest. But in all situations, results indicated that cows with the lowest initial SCC had the lowest risk for first clinical mastitis, without any intermediate optimum.

Mastitis in the first year postpartum.

Limited information is available about the frequency and risk factors for lactation mastitis. The purpose of this study was to investigate frequency, risk factors, and outcome for lactation mastitis. We analyzed data from a cohort study of 350 mothers with healthy term infants, who were followed up for one year postpartum. Eighty-three women (23.7% of the sample) reported one or more episodes of mastitis symptoms, and 61 (17.4%) women reported symptoms including fever. Fifty-six women (16%) received one or more courses of antibiotics for mastitis. Thirty women (8.5%) of the total cohort had recurrent episodes of mastitis symptoms. A total of 123 episodes of mastitis symptoms were reported. No cases of abscess were reported. Using multiple logistic regression, the adjusted risk ratio for mastitis symptoms associated with sore nipples in the first month was 2.07 (95% CI = 1.17, 3.66). A reduced risk of mastitis was associated with maternal smoking during pregnancy, with supplementation with water in the first month, and with the use of a pacifier on a daily basis within the first month. A history of mastitis symptoms was associated with a longer overall duration of breastfeeding. Our results suggest that mastitis may be a marker for an ample milk supply. Mothers presenting with mastitis can be reassured that the outlook for continued successful lactation is good. Further research is needed to investigate the reasons for recurrence of mastitis and the etiology of episodes occurring late in lactation.

Metabolic loads to be expected from different genotypes under different systems

AbstractThe strategy most widely adopted to improve milk production efficiency is to increase yield per cow. To date, this has been achieved primarily through genetic selection and improved nutrition. Achievement of very high individual yield has had its down-side, especially in terms of reduced reproductive efficiency and there is now quite widespread concern that the high genetic merit cow is at greater risk of metabolic disease than her unimproved counterpart. To quote from the recent Farm Animal Welfare Council Report on Dairy Cow Welfare (FAWC, 1997): ‘High metabolic turnover in cows can be associated with a greater risk of mastitis, lameness, infertility and other production diseases…’. Whilst there can be little doubt that metabolic turn-over is indeed higher in high merit cows, it is not safe to assume that this necessarily equates with more risk; metabolic turn-over is higher in an elephant than in a mouse but risk is certainly not. Metabolic load might be a better term to use. If we think, simplistically, of this being the ‘strain’ on a system it is logical to expect an inverse relationship between metabolic load and health. The extrapolation to high genetic merit cows being at greater risk then presupposes that they experience an increased metabolic load but there has been no rigorous evaluation of whether this is so. In this review we will consider what is meant by metabolic load, examine in qualitative theoretical terms what degree of load might be expected from different commercial systems and present some recently obtained data which addresses directly the question, is metabolic load greater in high genetic merit cows?

Association between milk somatic cell counts up to 400,000 cells/ml and clinical mastitis in French Holstein cows

The relationship between somatic cell counts (sccs) up to 400,000 cells/ml in individual cows and clinical mastitis was studied by collecting monthly records for a year from 101 Holstein herds...

Associations between use of electric cow-trainers and clinical diseases, reproductive performance and culling in Swedish dairy cattle

The aims of this follow-up study were: (a) to evaluate the role of ECT technology as a risk factor for several diseases; and (b) to determine if the effects of these diseases on cows' reproductive performance and as risk factors for culling are influenced by exposure to ECTs. Diseases considered were retained placenta, metritis, ketosis, cystic ovaries, silent heat, milk fever, clinical mastitis, and foot and leg problems. We used historical and contemporary controls (with control herds selected to match the experimental herds for size and location). Data consisted of 10264 Swedish Red and White (SRB) and 5461 Swedish Friesian (SLB) lactation records in 150 herds of which 33 used cow-trainers. Logistic regression was used to estimate the effects of parity and exposure to electric cow-trainers on the risks of diseases and the effects of diseases and exposure to electric cow-trainers on risk of culling. The least-squares procedure was used to estimate the effects of diseases on reproductive performance. The dominant effects associated with use of electric cow-trainers were an increased risk for silent heat, clinical mastitis, ketosis and culling relative to cows in herds not using cow-trainers. Diseases had negative effects on reproductive performance and the effects were larger for cows in herds using cow-trainers. In herds using electric cow-trainers, the largest increase in the interval from first service to conception (58 days) was caused by the occurrences of silent heat, cystic ovaries and the combination of two or more diseases. Retained placenta, metritis, cystic ovaries, clinical mastitis and a combination of two or more diseases increased the risk of culling about two times relative to healthy primiparous cows with the increase being greater for cows in herds using cow-trainers. Silent heat did not increase risk of culling in control groups, but was the largest risk factor for culling in the exposed group. We concluded that exposure to electric cow-trainers increased the incidence risk of silent heat, clinical mastitis, and ketosis and changed silent heat from a neutral disease with respect to culling to a major risk factor. Finally, exposure to cow-trainers increased the general negative effect of diseases on the cows' reproductive performance and risk for culling.

Case control study of risk factors for toxic mastitis in 26 dairy herds

A retrospective case control study of farm level risk factors for toxic mastitis was carried out in November and December 1996. Twenty-six farms from mid-Somerset were visited: 13 case farms...

Identification of Risk Factors for Clinical Mastitis in Dairy Heifers

A nested case-control study was conducted to identify risk factors for clinical mastitis in heifers. Cases and controls originated from dairy herds that were enrolled in the Production Recording Scheme. Heifers that had been treated for clinical mastitis prepartum or on the day of parturition were eligible for inclusion as cases. The controls were heifers that had not been treated for clinical mastitis before parturition, during their first lactation, or during the dry period. In the final analysis, 4256 heifers with mastitis and 67,072 control heifers were included.An increase in the incidence of clinical mastitis in the herd, a decrease in the bulk milk somatic cell count, and an increase in the mean milk yield of the herd were associated with an increased risk for clinical mastitis. The risk varied among regions, and, depending on region, significant influences of both herd size and composition of the diet were observed. Heifers kept on pasture in summer were at a decreased risk for clinical mastitis. Calving in late spring or summer was associated with greater risk than was calving at other times of the year. An increase in age at first calving was associated with increased risk of mastitis. Mastitis was also more likely to occur in heifers leaking milk or in heifers that had a low milk flow rate in the subsequent lactation. For purchased heifers, risk factors were identified in both their previous and current herds.

Automatic monitoring of the health and metabolic status of dairy cows

The aim of this study was to prioritise the objectives of research into new sensing systems to monitor routinely the health of dairy cows. An analysis of reasons for death and culling of cows and a survey of available sensor techniques suggested that the most suitable cow health events for routine monitoring are parturition, mastitis, and the malfunction of energy, protein, and mineral metabolism. Physical events such as parturition could be detected by image analysis and acoustic monitoring. Nutritional and metabolic conditions could be monitored by chemometric techniques to detect analytes such as acetoacetate or urea in milk and acetone in breath. Viral and bacterial proteins and hormones such as progesterone, could be detected automatically by antibody-specific biosensors provided that a suitable sample gathering system can be developed. A time sequence is proposed here to classify a hierarchy of events occurring in health or metabolic disturbance. It has been proposed that there is a primary event which should be the target for monitoring. Monitoring methods which rely on transducers to detect secondary and tertiary events, such as conductivity, milk yield change and temperature, have limited specificity and high numbers of false positives unless supported by robust models to integrate data from a number of sources. Although the technology to sense particular conditions could be developed, it is not clear whether veterinary and nutritional models are sufficiently well developed to allow decisions to be made based on the sensor data alone. Research is needed to determine the costs and reduced losses which may arise from early detection and treatment of disease. Models should include the subsequent risks for other health conditions, for example the effect of sub-clinical ketosis on the risk of mastitis or infertility.

Field Trials of a Vaccine Against Bovine Mastitis. 1. Evaluation in Heifers

A vaccine was developed against bovine mastitis based on inactivated, highly encapsulated Staphylococcus aureus cells; a crude extract of Staph. aureus exopolysaccharides; and inactivated, unencapsulated Staph. aureus and Streptococcus spp. cells. This vaccine was tested on 30 heifers during a 7-mo period. The 30 heifers were randomly assigned to three groups of 10 heifers each. The prepartum group received two injections of the vaccine at 8 and 4 wk before calving, and the postpartum group received two injections at 1 and 5 wk after calving. The control group received two injections of a placebo at 8 and 4 wk before calving. The vaccine or the placebo was administered subcutaneously in the brachiocephalicus muscle of the neck. The frequencies of intramammary infections caused by Staph. aureus were reduced from 18.8% for heifers in the control group to 6.7 and 6.0% for heifers in the prepartum and post-partum groups, respectively. This protective effect was maintained for at least 6 mo. The relative risk of mastitis caused by Staph. aureus was 0.31 and 0.28 for heifers in the prepartum and postpartum groups, respectively, compared with that for heifers in the control group. The results of the trial indicated the effectiveness of the vaccine in decreasing the incidence of intramammary infections caused by Staph. aureus. A slight but nonsignificant increase occurred in fat production in the milk of vaccinated cows. The vaccine had no observable effect on somatic cell count or streptococcal infections.

Inter-relationships of periparturient diseases in dairy cows.

The associations between periparturient diseases in 3603 lactations over three calving seasons were assessed on 10 dairy farms in the south west of England by using logistic regression. Calf mortality and dystocia were strongly associated. Twinning and dystocia were important predictors of calf mortality. Twinning was also a significant predictor for retained fetal membranes. Retained fetal membranes, twins, calf mortality and dystocia, in that order of importance, were risk factors for vulval discharge. Twinning, dystocia, retained fetal membranes and lameness before service increased the risk of mastitis before service. Similarly, mastitis and dystocia before service increased the risk of lameness before service. Oestrus was less likely to be observed in cows that had twinned or suffered lameness before service, the latter having a significantly greater influence in first calvers than older cows.

Nutrition and MASTITIS

Increasing evidence presents a relationship between nutrition and mammary resistance to infection. The role of nutrition in mammary resistance has been best defined for antioxidants. To optimize this interaction, rations should be balanced and formulated for lactational stage. Although supplementation of nutrients with antioxidant function may enhance immune resistance against infections, therapeutic roles for nutritional management of clinical mastitis, as yet, are not well documented. The need to monitor herd antioxidant status as part of a mastitis control program is critical because (1) antioxidant supplementation improves mammary resistance to infectious disease during the most critical period for enhanced resistance, the dry and early postpartum periods; and (2) dry cows and heifers often are on a marginal plane of Se supplementation, particularly during periods of risk for mastitis and reproductive disorders. In areas where forages contain less than 0.1 ppm Se (dry matter) because of low soil availability, herds should be tested for Se status and, if found to be below optimum levels, increased dietary supplementation or sustained-release Se boluses should be considered. Similarly, vitamins A (or beta-carotene) and E status should be monitored in herds, especially confined herds receiving a large proportion of ensiled forages.

A Randomized Blind Trial on Dry Cow Antibiotic Infusion in a Low Somatic Cell Count Herd

The objective of the study was to evaluate the effect of administration of antibiotics to cows at dry-off in a low SCC herd. Cows were infused at dry-off with an intramammary antibiotic on the left or the right side of the udder. Selection of the infused quarters was random, and all people evaluating the occurrence of mastitis were unaware of which half of the udder was infused. The quarters that were infused with an antibiotic showed a significantly lower incidence of clinical mastitis in the dry period. Quarters that were uninfused had 10 cases of clinical mastitis versus 1 case in quarters that were infused with antibiotics. The quarters that were infused showed a reduction of minor pathogens at calving. The uninfused quarters showed little evidence of spontaneous cure during the dry period.Milk leaking was frequent during the drying off period. Milk leaking was also associated with the occurrence of clinical mastitis later in the dry period. Cows that leaked milk had a four times greater risk of clinical mastitis in the dry period.

Nonlinear Mixed Model Analyses of Five Production Disorders of Dairy Cattle

A standardized threshold model was used to estimate herd variability and the impact of some risk factors on the incidence of retained placenta, metritis, ketosis, ovulatory dysfunction, and mastitis. Data consisted of records for 18,110 Swedish Red and White cows in 924 herds and 14,940 Swedish Friesian cows in 772 herds. Only first, second, and third parity cows were included, and the breeds were analyzed separately. Herds were considered to be random effects, and variance components were estimated by the counterpart of REML for a threshold model. Estimated intraherd correlations varied from .04 to .18 and were lowest for the incidence of retained placenta (for both breeds) and highest for ketosis and ovulatory dysfunction for Swedish Red and White and Swedish Friesian breeds, respectively. Parity increased predicted lactational incidence risks for all disorders except metritis, but season of calving had no profound effect. Dystocia and stillbirth increased the risk of retained placenta; dystocia and retained placenta increased the risk of metritis. The risk of ketosis was not influenced by any of the considered risk factor diseases, and the risk of mastitis was influenced only by retained placenta for Swedish Red and White cows. For both breeds, the risk of ovulatory dysfunction was increased by metritis and ketosis.

Effects of Dry Period Length on Clinical Mastitis and Other Major Clinical Health Disorders

Four, 7-, and 10-wk dry periods were randomly assigned to 366 dairy cows in eight herds. A multiple polytomous logistic regression analysis was conducted with the objective to reveal possible important effects of the dry period on the risk of contracting major clinical health disorders. Several complex statistical interactions were revealed. Complications around and after drying off occured least frequently at 7-wk dry periods. There was little evidence of an effect of the dry period on the risk of clinical mastitis and other severe clinical disorders around and after calving. With short calving intervals, the risk of occurrence of complications at calving decreased with the length of the dry period. This relation was reversed at longer calving intervals. Dry period lengths of approximately 7 wk appear to be associated with the lowest risk of clinical health disorders, but other factors like milk yield at drying off and previous mastitis are much more important predisposing factors.

Mastitis among lactating women: Occurrence and risk factors

Puerperal mastitis is a potentially serious illness among lactating women which traditionally has been thought to be associated with primiparity, stress, improper nursing technique, and incomplete emptying of the breast. However, none of these putative associations has been examined analytically in recent years. Further, the incidence of mastitis in the United States has not been estimated since 1975, although the prevalence of breastfeeding has increased dramatically since then. In this retrospective cohort study of 966 lactating women, the cumulative incidence of mastitis in the first seven weeks postpartum was 2.9%. This incidence was associated with professional, technical, or managerial occupation in both parents (rate ratio = 12.29; 95% CI: 1.62, 93.43) and with giving birth in the hospital delivery room, rather than the labor room (rate ratio = 4.05; 95% CI: 0.92, 17.83). Parity was not associated with risk of mastitis in this sample.

Tramped Teats – Clinical Mastitis Disease Complex in Tied Cows. Environmental Risk Factors and Interrelationships with Other Diseases

The effects of stall length, manure system, type of bedding and calving disorders on incidence rates of tramped teats, udder injuries, and clinical mastitis in Swedish Red and White tied cows, as well as interrelationships between these 3 disorders were investigated. Data used consisted of 370 herds, for a total of 45,133 cow records. Cows in herds with liquid manure system were at higher risk of udder injuries and mastitis than in herds with solid system. Lower risk of both udder injuries and mastitis was found for cows in herds with short stall size (less than 180 cm) compared to herds with stalls of 205-219 cm length. It was suggested that other factors, such as slipperiness of the stall floor and presence and type of feeding barrier, must be considered when the effect of stall characteristics on tramped teats is investigated. In farms with solid manure system cut straw or sawdust bedding increased the risk of tramped teats and mastitis relative to uncut straw. Parity and calving disorders were important risk factors for udder health and their effect was greater in herds with liquid manure system. Tramped teats and udder injuries were the most serious risk factors for clinical mastitis.

Epidemiology of mammary gland disorders in multiparous Finnish Ayrshire cows

Logistic regression was used to investigate the effects of host characteristics, milk production and 23 veterinary diagnoses on the odds of contracting acute and chronic mastitis, and teat injury among 41 989 multiparous Finnish Ayrshire cows that calved during 1983. Cows which had higher previous-lactation milk yields were at increased risk of acute and chronic mastitis, and teat injury. All of the mammary gland disorders were directly interrelated. Abomasal disorder, indoor hypomagnesemia, prolapsed uterus and vagina, and abortion were not risk factors for any of the three mammary gland disorders; however, retained placenta, udder edema, ketosis, non-parturient paresis, rumen acidosis, traumatic reticuloperitonitis, silent heat, ovarian cyst and other types of infertility were all direct risk factors for at least two mammary gland disorders.

Intramammary infections and risk factors for clinical mastitis in herds with low somatic cell counts in bulk milk.

Ten herds with low somatic cell counts in bulk milk had an incidence of clinical mastitis of only 2.2 per 100 cows whereas 10 other herds with similarly low cell counts had an incidence of 53.6 per 100 cows. The major pathogens in the herds with a high incidence were Escherichia coli, Streptococcus uberis, Staphylococcus aureus and the coagulase-negative staphylococci. The percentage of uninfected quarters in the herds with a high incidence of clinical mastitis was 21.4 per cent compared with 12.2 per cent in the herds with a low incidence of clinical mastitis. The prevalence of coagulase-negative staphylococci, Corynebacterium bovis and Micrococcus species was higher in the herds with a low incidence of clinical mastitis. There was a significant linear relationship between the percentage of uninfected quarters and the incidence of clinical mastitis in the herds with a high incidence of clinical mastitis. In herds with a low incidence of clinical mastitis significantly less teat disinfection after milking was practised. The results suggest that infections with minor pathogens tend to protect cows against mastitis, and that teat disinfection after milking may increase the percentage of uninfected quarters and lead to an increased risk of clinical mastitis in herds with low somatic cell counts in bulk milk.

Periparturient Hypocalcemia in Cows: Effects on Peripheral Blood Neutrophil and Lymphocyte Function

Periparturient dairy cows are quite susceptible to intramammary infections and clinical mastitis, epidemiologic evidence indicates that parturient paresis (milk fever) greatly increases the risk of mastitis, although a causal relationship has not been established. In the present experiment the effects of hypocalcemia at parturition on the immune status of dairy cows were investigated. Ten healthy, multiparous Holstein cows were fed a high Ca diet prepartum to induce hypocalcemia at parturition. Five of these cows received intramuscular parathyroid hormone (crude synthetic N-terminus 1–34) to prevent hypocalcemia at parturition. Effects of hypocalcemia on various neutrophil and lymphocyte functions were determined during the periparturient period, ranging from 6 wk prepartum to 5 wk postpartum. All cows exhibited severe loss of immune cell function in the weeks surrounding parturition. Hypocalcemia or the development of parturient paresis did not exacerbate the immune cell dysfunction. This implies that the degree of hypocalcemia observed did not have a large or irreversible influence on neutrophil and lymphocyte function in periparturient cows.