Effect Of Subclinical Mastitis Research Articles

Effects of subclinical mastitis on automatic milking system data, hematological and biochemical parameters, and milk composition in Holstein cows.

Subclinical mastitis decreases milk production and quality, despite the normal appearance of the mammary glands and milk. Herein, we aimed to investigate changes in factors monitored via automatic milking systems (AMS) prior to subclinical mastitis onset and identify differences in hematological and biochemical parameters and milk composition at subclinical mastitis onset. Thirty-two Holstein cows were divided into two groups according to somatic cell counts (SCC) from AMS and milk composition analysis and the California mastitis test (CMT): healthy cows (controls [CON], n=16, SCC <500×103 cells/ml and negative for CMT) and cows with subclinical mastitis (SCM, n=16, SCC ≥500×103 cells/ml and positive for CMT). Eventually, 121 milk samples from the CON ([mCON], n=60) and SCM ([mSCM], n=61) groups were obtained; SCM samples were categorized as those from non-inflamed (mNQ) or subclinically-inflamed (mIQ) quarters. We evaluated AMS factors; hematological, biochemical, and milk composition parameters; and bacterial isolation. In cows with SCM, milk yield decreased and electrical conductivity (EC) changed before disease onset. Milk EC decreased in mNQ although increased in mIQ (p<0.05). The SCM group had higher globulin levels and lower basophil counts; albumin-to-globulin ratio; and total cholesterol, albumin, and blood urea nitrogen levels than the CON group (p<0.05). The mIQ group had higher SCC but lower levels of lactose and milk solids-not-fat than those in the mCON and mNQ groups (p<0.05). The mCON group had higher levels of milk non-protein nitrogen than the mNQ group (p<0.05). Opportunistic mastitis pathogens were isolated in the mIQ group. Changes in milk yield and EC measured using AMS occurred prior to subclinical mastitis, which may be associated with variation in basophil counts; albumin-to-globulin ratio; and total cholesterol, albumin, BUN, globulin, SCC, milk lactose, and milk solids-not-fat levels at disease onset. These findings provide new insights into early-stage subclinical mastitis.

Effect of subclinical mastitis on milk taurine concentration in dairy cows

The objective of this study was to evaluate whether taurine has any role in bovine subclinical mastitis, and the relationship between milk taurine concentration and somatic cell count. Forty milk samples from dairy cows aged 3 to 6 during lactation were used for this research. The California Mastitis Test (CMT) and somatic cell counts (SCC) were determined in the diagnosis of subclinical mastitis. The subclinical mastitis group consisted of 20 milk specimens positive for CMT and SCC&gt;200.000/ml of milk. The control group consisted of 20 milk specimens negative for CMT and SCC&lt;200.000/ml of milk. A bovine-specific taurine enzyme-linked immunosorbent assay kit was used to determine the taurine concentration in the milk. The milk serum taurine concentrations were determined as 232.1±89.8 pg/ml in the control group and 158.0±55.6 pg/ml in the subclinical mastitis group. These results determined that the taurine concentration in milk with subclinical mastitis decreased approximately 1.5 times compared to healthy milk (P&lt;0.05). A significant negative correlation was determined between the taurine concentration in cow’s milk with subclinical mastitis and the number of somatic cells (r= -0.933; P&lt;0.001). From the findings of this study, it was concluded that both somatic cell counts and the measurement of taurine in cow’s milk could be used to monitor mammary health.

Assessing the Impact of Subclinical Mastitis on Dairy Cattle in Balochistan

Subclinical mastitis is a common and costly disease affecting dairy cattle. This research aims to examine the impact of subclinical mastitis on dairy cattle production and evaluate methods for controlling and reducing its prevalence. The study will focus on the effects of subclinical mastitis on milk yield and quality, as well as its impact on animal health and welfare. The goal is to provide valuable insights for dairy farmers and industry professionals to improve management practices and reduce the economic losses associated with subclinical mastitis. A total of 144 cattle from 25 different farms were analyzed for subclinical mastitis, with 54.86% (n=79) of the cattle found to have subclinical mastitis. Results revealed a moderate association between the prevalence of subclinical mastitis as determined by the CMT test and the UdderCheck® test. The study also found that the most common bacteria causing subclinical mastitis were Coagulase Negative Staphylococci (CNS), Coliforms, Streptococcus spp. and Staphylococcus aureus (CPS). The results of the antibiotic sensitivity test showed that ciprofloxacin was the most effective in treating various pathogens associated with mastitis. The results of this study highlight the need for further investigation into the impact of subclinical mastitis on dairy cattle, particularly with respect to the various bacteria causing the condition and the effectiveness of different antibiotics in treating it. .

Subclinical Mastitis Detected during the Last Gestation Period Can Increase the Risk of Stillbirth in Dairy Calves.

We hypothesized that subclinical mastitis detected during the last gestation period can increase the risk of stillbirth in dairy calves. The aim was to investigate the relation of subclinical mastitis detected during the last gestation period and its pathogens with the stillbirth of calves. Cows from the 210th day of pregnancy were selected for the study. They were divided into two groups: the first group-subclinical mastitis was confirmed on the farm by the California mastitis test (CMT); the second group of cows-mastitis was not confirmed by the CMT test. Groups of cows were compared according to the results of their calving-the number of stillborn calves. A stillborn calf was defined as a calf that dies at birth or within the first 24 h after calving, following a gestation period of 260 days. Our results suggest that decreasing the incidence of subclinical mastitis during the last gestation period (from the 210th day of pregnancy) can decrease the risk of stillbirth in dairy calves. Further, it is important to identify the pathogen because the highest risk of stillbirth was found in cows with mastitis caused by Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, pathogenic Staphylococci and other Streptococci. Cows at the first calving had a 1.38-1.65-times higher risk of having stillborn calves than cows of parity ≥ 2. From a practical point, veterinarians and farmers can consider the effect of subclinical mastitis during late gestation on the risk of stillbirth and it could help for strategies of optimizing reproductive performance in dairy cows.

The effect of subclinical mastitis on qualitative composition of milk

A complex of mammological studies was carried out in experimental farms of the Vladimir region. Lactating cows underwent an express diagnosis of the health of the udder with the California mastitis test, and based on the result obtained, three groups of animals were formed, 20 animals each. The animals of the first group had a questionable reaction to the California express method; animals the second - weakly positive; the third group included blood with negative reaction to tests (control). In studies of milk from cows with suspected udder inflammation, a decrease in dry matter content and a change in the quantitative ratio between the constituents of milk were found. The dry matter content in the milk of the cows of the 1st experimental group exceeded this indicator in the milk of the 2nd group of cows by 7.6%; and lagged behind the control by 12.8%. When milk from sick cows was heated, some of the whey proteins were destabilized. The titratable acidity of the milk of the cows of the 1st experimental group was within the limits stipulated by GOST for the prepared milk, while in the cows of the 2nd group it was reduced to 13.22 ± 0.16 ° T, which indicates the onset of the inflammatory process in the mammary gland. When carrying out echographic visualization of the excretory system of the udder of cows, the following features were revealed: with a large volume of the milk cistern, the main type of branching of the excretory system was observed; with medium and small - mixed type; and with mild - loose As a result of the experiment, it can be concluded that animals with a weakly positive reaction to the California Mastitis Test are less productive and they receive milk of lower quality, which is practically not suitable for further use for technological purposes. However, according to the current Technical Regulations, this milk can correspond to the first or second grade.

Study on prevalence and bacterial etiology of mastitis, and effects of subclinical mastitis and stage of lactation on SCC in dairy goats in Egypt.

In Egypt, inadequate information on prevalence and epidemiology of caprine mastitis is available. This study was designed to investigate prevalence and etiological agents of caprine mastitis and assess the efficacy of somatic cell count (SCC) as marker of subclinical mastitis (SCM) in dairy goats. This study was carried out on 249 randomly selected lactating goats in different lactation stages and examined clinically. Of these animals, 477 milk samples were aseptically collected and screened for bacterial carriage. SCC was assessed in 234 apparently normal milk samples, and SCC ≥ 106cells/ml was indicator for SCM. Prevalence of clinical mastitis (CM) was 33.73% and 16.87% at animal and udder-half levels, respectively. SCM was 52.56% in the apparently healthy halves. Culture results proved single infection in 49.69% of samples, mixed infection in 23.9% of samples, and 26.41% of samples were negative. Coagulase negative staphylococci (CNS) were the most predominant bacteria (58.75%), then Staphylococcus aureus (S. aureus) (24.375%), and Streptococci (1.875%) were the least. No significant difference was recorded between mean of SCC in bacteriologically positive and negative samples, neither in those with SCC ≤ 106 nor with SCC ≥ 106cells/ml both in middle and late lactation stages. Besides, the percentage of animals harboring SCC ≥ 106cells/ml and negative for bacteriology in late lactation stage was 3 times (28.57%) more than in midlactation (9.3%). We can assume that SCC is not proper indicator for intra-mammary inflammation (IMI) in goats, and bacteriological examination remains more efficient, despites being time consuming and expensive.

Effect of subclinical mastitis in compositional change in milk and blood parameter of crossbred dairy cow

Effect of subclinical mastitis in compositional change in milk and blood parameter of crossbred dairy cow

Effect of subclinical mastitis on the yield and cheese-making properties of ewe’s milk

Abstract This review covers an update of scientific knowledge about productive and technological consequences of subclinical mastitis in sheep milk. The literature reports individual milk yield losses of 2.6–43.1 %, being modulated by several factors as infection severity, production level, causal agents, and unilateral or bilateral IMI (1 or 2 infected glands, respectively). A compensatory increase of milk production from the uninfected gland when only one half was infected has been quantified in 6.6 %, compared with healthy halves of control sheep. This compensatory adaptation highlights the risk of underestimating subclinical mastitis in sheep. The mammary gland response is quick and milk yield losses in absolute terms remained constant within the following weeks, both when infection appear during lactation and when it is present from lambing. With respect to the changes on main components in milk due to subclinical mastitis it has been clearly established a decrease in the concentration of lactose and an increase of that of whey proteins. The role played by lactose as an osmotic regulator results in a more accentuated decrease of its concentration in milk. This is why lactose is considered at present as a reliable potential indicator of subclinical mastitis. Whey proteins increase as a result of the increase of the blood-milk barrier permeability and the increased proteolysis of caseins. However, the content in milk of fat and casein are modified depending on the magnitude of milk yield reduction, being affected by a concentration or dilution effect. In any case, the ratio casein to protein (parameter independent of the milk volume) decreases as a result of infection. The impairment of physical and chemical characteristics due to decreased udder health status is the responsible of the negative effect of increased SCC on the coagulation properties of milk, the curd yield and the quality of cheese. Low ratio of casein to protein in high bulk tank SCC milk enhances the extension of the rennet coagulation time (RCT) and curd firming time (k20) because there are more serum proteins and the stability of casein micelles are reduced as a result of hydrolysis. Those changes in turn led to poor syneresis, lower cheese yield, increased moisture content and lower fat and protein content in cheese. Finally, there is a favourable relationship between lactose and milk technological properties because the decrease of this component in case of mastitis is associated with an increase of milk pH. Thus, the three parameters, SCC, pH, and lactose affect, contemporarily and independently, milk quality and coagulation properties, and this is why have been highlighted as potential indicators traits for improving cheese-making ability of sheep milk.

Subclinical intramammary infection does not affect bovine milk ethanol stability

The present study hypothesized that intramammary infection (IMI) might reduce milk ethanol stability (MES), mainly when IMI is caused by major pathogens. Thus, this study evaluated the effect of IMI on bovine MES using a natural exposure experimental design. Ninety-four lactating cows from five dairy herds were selected once they were determined to have an IMI, based on milk bacteriological culturing with positive isolation and somatic cell count (SCC) &gt; 200×103 cells/mL in two out of three composite milk samples collected during three consecutive weeks. After selection, cows were sampled a second time (within two weeks) for evaluation at mammary quarter level (n = 326): milk yield (kg/quarter/day), MES, composition (fat, protein, lactose, casein, total solids and solids-non-fat), and bacteriologic culture. The effect of subclinical mastitis on MES was tested by two models: 1) comparison of healthy vs. infected quarters; and 2) comparison of contralateral mammary quarter within cow. The only milk composition variable associated with MES was lactose (r = 0.18; P &lt; 0.01). Subclinical IMI did not affect MES when the comparison was performed using both models (1 and 2). Likewise, MES did not change when infected quarters were sorted into two groups of pathogens (major, minor and infrequent; and contagious, environmental, minor and infrequent) and compared with healthy mammary quarters. Considering the results of both models, subclinical IMI did not affect MES of dairy cows.

The effect of subclinical mastitis on the concentration of immunoglobulins A, G, and M, total antioxidant capacity, zinc, iron, total proteins, and calcium in she-camel blood in relation with pathogens present in the udder.

The present study aims to evaluate the amount of immunoglobulins A, G, and M in she-camel blood serum in relation with the presence of pathogens in the udder, and to compare the antioxidative capacity and the concentration of zinc, iron, total proteins, and calcium. Milk and blood samples from she-camels from south Jordan were taken; according to milk bacteriological examination, the animals were divided into two groups: (Gm) which contained samples of milk contaminated with bacteria and (Gh) which contained uncontaminated milk samples. Milk and blood were sampled from 30 females and examined for the concentration of immunoglobulins A, G, and M and for the presence of pathogens in milk. Total antioxidant capacity, zinc, iron, total proteins, and calcium concentrations in blood were determined. Milk samples were checked for the presence of pathogens. She-camels for the study were of similar age and productivity in the middle stage of lactation. It was determined that the presence of pathogenic bacteria infecting the udder quarters had considerably influenced the values of immunoglobulins G, A, and M, total antioxidant capacity, and zinc and total protein concentration (p < 0.05) in blood serum; no significant difference in iron and calcium concentration was determined. Subclinical mastitis has a crucial role in increasing the concentration of immunoglobulins in serum; some parameters measured in blood (zinc, total antioxidant capacity, total proteins) could be indicative for the presence of inflammation in she-camels.

117 Subclinical Mastitis Reduces Ovulation and Oocyte Quality in Milk-Producing Cows

The aim was to evaluate the effect of subclinical mastitis by somatic cell count (SCC) on follicular dynamics, ovulation, oocyte and cumulus cell quality, exosome size and concentration in milk-producing cows. Crossbred cows (Bos taurus × Bos indicus; that is, Holstein × Gyr) were randomly allocated to control (SCC &lt;200,000 cells mL−1] and mastitis (SCC &gt;400,000 cells mL−1) groups. In experiment 1 (follicular dynamics), cows (n = 57) were submitted to ultrasonographic evaluations every 24 h, after removal of an intravaginal progesterone device (Day 8) up to Day 10. From Day 10, ultrasound evaluations were performed every 12 h, until ovulation or until 96 h after progesterone device withdrawal, in order to follow final dominant follicle growth and ovulation. In experiment 2 (oocyte, cumulus cells, and follicular fluid evaluation), cows (n = 23) were submitted to follicular aspirations, preceded by synchronization of the emergence of the follicular wave. The levels of target genes in cumulus cells (BCL2, BAX, PI3K, PTEN, FOXO3) were evaluated by RT-qPCR. In the follicular fluid, the exosomes were isolated for evaluation of particle size. Data were analysed by the Glimmix procedure of SAS (SAS Institute Inc., Cary, NC, USA). Ovulation rate (P = 0.09) was higher in control cows [control 77.42% (24/31) and mastitis 57.69% (15/26)]. Viable oocyte rate (P = 0.01) was also higher in control cows [control 59.1% (130/220) and mastitis 41.9% (125/298)]. The dynamics of follicular growth did not differ between groups. The number of degenerate oocytes (P = 0.001) was higher in cows of the mastitis group. In the evaluation of cumulus cell gene expression, there was a higher abundance of BAX transcripts (P = 0.003) in cells of mastitis cows. Additionally, the mean and mode of exosome diameter in mastitis cows were smaller (P = 0.03 and P = 0.02, respectively). In conclusion, ovulation rate, oocyte quality, and follicular fluid exosome diameter were lower in cows with subclinical mastitis, demonstrating a link between mammary gland sanitary status and reproduction.

Effects of Subclinical Mastitis on Serum Estradiol and Tumour Necrosis Factor Alpha Levels During Estrus in Dairy Cows

Effects of Subclinical Mastitis on Serum Estradiol and Tumour Necrosis Factor Alpha Levels During Estrus in Dairy Cows

On effects of subclinical mastitis and stage of lactation on milk quality in goats

Bulk milk is the mixture of all the milked udders in a given herd. Nowadays, about 15–40% of the udders in most herds are intramammary infected by different bacteria species, mainly coagulase negative staphylococci. The presences of bacteria in the lumen of the mammary gland induce impairment of milk quality and increase the number of somatic cells. A positive relationship between % casein (casein/total protein) and curd firmness (CF) and negative relationship between lactose, or somatic cell count (SCC) and CF are associated with bacterial infection and with late lactation milk, and therefore with reduction in cheese yield and quality. On the other hand, in milk of goats with intramammary infection, the correlation between the levels of fat, protein, casein and curd yield is minor compared to milk of uninfected animals. Thus, gross milk composition is an insufficient predictor of milk quality for cheese production, since a high percent of the bulk milk originates from subclinically infected glands. Research carried out in the past few years highlighted the effectiveness of lactose as a predictor of milk quality. The correlation between lactose and CF was higher than that for % casein and SCC. Lactose concentration of ≤4% is associated with non-coagulating milk and therefore, such milk is unsuitable for making cheese, but still meets the criterion for consumption as pasteurized milk. A model that describes the simultaneous and close association between reduction in lactose concentration and milk yield on the one hand and reductions in lactose concentration and milk quality on the other hand is presented. The physiological and biochemical basis for deterioration of milk quality in subclinically infected and in late lactation animals is reviewed and suggestions to improve the quality of milk produced by farmers and acquired by dairies are presented.

Short communication: Effect of subclinical mastitis on proteolysis in ovine milk

The aim of this work was to evaluate the effect of intramammary infection (IMI) on the endogenous proteolysis of milk. Four control checks were carried out in the half-udder milk of 10 ewes that acquired unilateral subclinical mastitis. Two of these checks were conducted before the infection was established and 2 after. Ten healthy ewes were tested as a control group. The presence of a subclinical IMI involved an increase of the products of casein hydrolysis, the proteose-peptone (p-p) fraction and minor (m) caseins, and a decrease of β-casein. As a result, a significant increase in the proteolysis index (PI), calculated as the ratio of m-casein to the sum of caseins (α + β + κ), took place. α-Casein and κ-casein were not significantly affected by IMI. Correlations confirmed the scenario: log10 of somatic cell count (SCC) was positively correlated with p-p content and negatively with β-casein, whereas log10 SCC was not correlated with α-casein or κ-casein. On the other hand, p-p content was positively correlated with m-casein and PI and negatively with β-casein, but no correlation was detected between p-p content and α- or κ-casein. Furthermore, between casein fractions, m-casein was only significantly correlated with β-casein. These results suggest that use of indices of proteolysis of caseins such as p-p, m-casein, and PI, could be applied together with SCC to evaluate the cheese-making quality of milk.

The effect of subclinical mastitis on milk yield in dairy goats

The aims of this study were to estimate milk yield (MY) losses associated with subclinical intramammary infection (IMI) in dairy goats and to assess if somatic cell count (SCC) can be used to estimate such MY losses. We used 2 data sets to study these questions. The first data set consisted of 5 herds. Milk production and SCC were recorded during 1 lactation. From approximately 100 does in each herd, milk samples were collected on 3 occasions during lactation for bacteriological culture. Linear mixed regression was used to estimate the effect of IMI on MY. The second data set consisted of 6 large herds, in which some of the goats had an extended lactation (≥2 yr). Milk yield and SCC data were recorded without bacteriological culture. The data showed that bacterial infection was related to an increase in SCC. Infections with major pathogens were rare and associated with a decreased MY; infection with coagulase-negative staphylococci did not affect MY, whereas infection with Corynebacterium bovis was associated with increased MY. A negative correlation was observed between SCC and MY, but the data suggested that this negative correlation was attenuated rather than caused by IMI. Furthermore, SCC seemed to be affected by MY via a dilution effect. Hypotheses about biological mechanisms behind these observations are discussed. This paper shows that MY losses caused by subclinical udder infections are limited in goats, and that SCC cannot be used to estimate the magnitude of these losses.

Effect of Subclinical Mastitis on Milk of Cross Bred Sahiwal x Jersey Cows: A Biochemical Study

Effect of Subclinical Mastitis on Milk of Cross Bred Sahiwal x Jersey Cows: A Biochemical Study

Subclinical mastitis in ewes and its effect on lamb performance.

Two studies were conducted to 1) assess the effectiveness of the California mastitis test (CMT) relative to direct microscopic somatic cell count (DMSCC) and(or) somatic cell count (SCC) procedures for detecting subclinical mastitis in ewes, 2) determine the incidence of subclinical mastitis based on repeated or single sample measures and organisms associated with the inflammation, and 3) assess the relationship between milk quality measures and lamb performance. The relationship between DMSCC and SCC scores was significant (P less than .01); 90% of the variation in DMSCC scores was accounted for by SCC scores. In contrast, CMT scores accounted for only 26% of the variation in DMSCC and 30 to 34% of the variation in SCC scores. Incidence of inflammation varied from 17 to 50% of ewes tested, depending on the study and the method of assessment. Staphylococcus species were cultured from 14/41 samples tested, with cultures of Streptococcus species (3/41) and Micrococcus species (1/41) also present. The effect of subclinical mastitis in ewes on lamb performance was minimal when assessed by regressing lamb weights on subclinical mastitis and milk quality scores. In conclusion, growth performance of lambs in a management system where they had access to supplemental feed was not influenced by the quality of milk produced by ewes, or by the degree of subclinical mastitic inflammation present when they suckled.

Citric acid concentration in subclinical mastitic milk.

The effect of subclinical mastitis on the citric acid concentration of cow's milk was studied by comparing milk from the mastitic quarter with that from a healthy quarter of the same udder. Forty-two pairs of fore-milk from the morning milking of 17 cows were examined and the citric acid content was measured by an automated carboxylic acid analyzer. The citric acid concentration deceased in subclinical mastitic milk and the extent of decrease was proportional to the degree of mastitis as expressed by the quarter difference value in concentration of Na + Cl in mM/l, i.e. the increase in the Na and Cl concentrations in the abnormal milk over that found in normal milk from the same udder. The correlation coefficient between the quarter difference value of Na + Cl and the value for citric acid was -0.77, (d.f. = 46, P less than 0.001) and a linear regression equation was obtained. The result showed clearly that subclinical mastitis is one of the causes of variation in the citric acid content of cow's milk. The quantitative change in citric acid concentration in subclinical mastitic milk is discussed with reference to the admixture theory for the formation of abnormal milk.

The effect of subclinical mastitis on the nutritive, technological and hygienic properties of cow milk

Abstract53 Paare von Gemelksproben aus Eutervierteln mit negativer und dubioser bis hoch positiver Reaktion wurden im Mastitis‐Test‐NK auf Veränderungen des Gehaltes der die Trockensubstanz der Milch bildenden Komponenten und auf Anwesenheit einiger pathogener Keime untersucht. Vom technologischen Standpunkt aus ist die Feststellung der Herabsetzung des Gehaltes von Casein, Lactose und Calcium in der Milch und die Verschlechterung der Labgerinnungsfähigkeit ungünstig. Vom nutritiven Standpunkt aus ist besonders die Herabsetzung des Calcium‐ und Phosphorgehaltes in der Milch aus erkrankten Eutervierteln wichtig. Bei 20–50% der Euterviertel mit nachgewiesenen subklinischen Euterentzündungen wurden in der Milch pathogene Keime festgestellt. Ähnliche Beziehungen wurden auch bei der Auswahl von Paaren der durch die Anzahl der Zellelemente klassifizierten Viertelgemelkproben festgestellt.

Effect of staphylococcal contamination of the bovine udder on milk yield.

Abstract Extract Reduction of milk yield from cows with clinical mastitis has been recorded by a number of workers (Shaw and Beam, 1935 Shaw, A. O. and Beam, A. L. 1935. The effect of mastitis upon milk production. J. Dairy Sci., 18: 353–357. [Google Scholar]; Rowland and Zein-El-Dine, 1938 Rowland, S. J. and Zein-El-Dine, M. 1938. The effect of subclinical mastitis on the solids-not-fat content of milk. J. Dairy Res., 9: 182–184. [Google Scholar]; McDowall, 1945 McDowell, F. H. 1945. Studies on the detection of mastitis in New Zealand dairy herds. V. Composition of milk from quarters reacting to the bromthymol blue test for mastitis. N.Z. Jl Sci. Tech., 27 A: 258–269. [Google Scholar]; King, 1967 King, J. O. L. 1967. The effect of mastitis on the yield and composition of heifer's milk. Vet. Rec., 80: 139–141. [Google Scholar]). In addition, the experimental infusion of cultures of Staphylococcus pyogenes into the udders of dairy cows produced clinical mastitis and substantial reductions in milk yields (Wheelock et al, 1966 Wheelock, J. V., Rook, J. A. F., Neave, F. K. and Dodd, F. H. 1966. The effect of bacterial infection of the udder on the yield and composition of cow's milk. J. Dairy Res., 33: 199–215. [Crossref], [Web of Science ®] , [Google Scholar])