Prevelance of Subclinical Mastitis in Organised Dairy Farm Using California Mastitis Test

Introduction

Mastitis is the most widespread and costly disease in dairy cattle occurring throughout the world. It is of particular concern for farmers in developing countries like India. Costs due to mastitis include reduced milk production, condemnation of milk due to antibiotic residues, veterinary costs, culling of chronically infected cows and occasional deaths. Moreover, mastitis has a serious zoonotic potential associated with shedding of bacteria and their toxins in the milk. Mastitis is caused by a wide spectrum of pathogens and, epidemiologically categorized in to contagious and environmental mastitis. Contagious pathogens are those for which udders of infected cows serve as the major reservoir. They spread from cow to cow, primarily during milking, and tend to result in chronic sub-clinical infections with flare-ups of clinical episodes. Contagious pathogens include: Staphylococcus aureus, Streptococcus agalactiae, Mycoplasma spp. and Corynebacterium bovis. On the other hand, environmental mastitis can be defined broadly as those intra-mammary infections caused by pathogens whose primary reservoir is the environment in which the cow lives. Environmental pathogens include E. coli, Klebsiella spp., Strept. dysgalactiae and Strept. uberis and the majority of infections caused by these pathogens are clinical and of short duration.

Mastitis can also be classified as either clinical or sub-clinical. Clinical mastitis is characterized by sudden onset, alterations of milk composition and appearance, decreased milk production, and the presence of the cardinal signs of inflammation in infected mammary quarters. It is readily apparent and easily detected. In contrast, no visible signs are seen either on the udder or in the milk in case of sub-clinical mastitis, but the milk production decreases and the somatic cell count increases. It is more common and has serious impact in older lactating animals than in first lactation heifers. Because of the lack of any overt manifestation, the diagnosis of sub-clinical mastitis is a challenge in dairy animal management and in veterinary practice.

Incidence of the disease

The incidence of mastitis is distributed over season, stage of lactation, and type of animal. The incidence of reported cases was the highest during monsoon season and the lowest during summer. Around 46% of affected animals were observed to lie within 30–90-day period of lactation. Species-wise highest incidence of the disease was observed in crossbred cows which implied that crossbred cows are more susceptible to the disease. Less incidence of the disease in buffaloes might be due to the thick and compact epithelium, thick keratin layer, and thick muscle sphincter in streak canal of udder of buffaloes as compared to crossbred cows and the similar results obtained earlier by Saini et al.

Economic Losses due to Mastitis

A study was conducted by Mukesh Kr. Sinha, N. N. Thombare, and Biswajit Mondal to assess the incidence and economics of subclinical form of bovine mastitis in Central Region of India. Daily milk records of 187 animals during three seasons were collected and subjected to analysis. The economic loss due to reduction in yield, clinical expenses, and additional resources used were quantified and aggregated. The losses due to mastitis in monetary terms were estimated to be INR1390 per lactation, among which around 49% was owing to loss of value from milk and 37% on account of veterinary expenses. Higher losses were observed in crossbred cows due to their high production potential that was affected during mastitis period. The cost of treating an animal was estimated to be INR509 which includes cost of medicine (31.10%) and services (5.47%). Inadequate sanitation, hygiene, and veterinary services were the main predisposing factors for incidence and spread of mastitis as perceived by the respondents.

California mastitis test

It is a simple cow-side indicator of the somatic cell count of milk. It operates by disrupting the cell membrane of any cells present in the milk sample, allowing the DNA in those cells to react with the test reagent, forming a gel. It provides a useful technique for detecting subclinical cases of mastitis.

Whiteside described a reaction between sodium hydroxide and milk that resulted in the thickening of mastitic milk. The utility of this reaction as a field test was limited by the fact that the reaction was sometimes difficult to observe, and would eventually occur even in normal milk. A refined version of the test, which enhanced its sensitivity, and eliminated the confounding effect of milk fat, uses an anionic surfactant, which forms a gel with the DNA in somatic cells in the milk.

Objective

To find out the prevalence of the subclinical mastitis in organized dairy farm using CMT

Review of literature

Kumar et al. in ,  2014 reviewed the  economic consequences of losses due to subclinical form of mastitis were assessed in terms of reduction in milk yield, medicine and veterinary expenses incurred, and additional resources used. The overall losses were estimated at INR 1390 per lactation, in which around 49% was due to reduction of milk production alone followed by veterinary expenses which accounted for 37% of the total loss. In crossbred cows and buffaloes, losses due to reduction in milk yield were worked out at INR700 and INR364, respectively. A greater loss in crossbred cows was observed due to their high production potential which was affected during the infection period.

 Kumar et al. in 2010 reported that  that the overall mastitis incidence was 9.28, 3.59 and 4.10% for crossbred cows, indigenous cows and buffaloes, respectively. The number of clinical mastitis cases differed significantly over different seasons, lactation and stage of lactation. Mastitis incidence was highest during the rainy season, followed by winterand summer. Animals in 30 to 90 days of lactation had a higher incidence. Mastitis was highest in 3rd and 4th lactations and was almost same for 1st, 2nd, 5th and higher lactations. Joshi and Gokhale, 2006 reported that An investigation on 250 animals from periurban farms indicated that the monsoon season was more prone to subclinical mastitis than summer or winter, prevalence increased with higher lactation number and animals in 4th–5th month of lactation were found more susceptible (59.49%), hind quarters were found more affected (56.52%) than fore quarters (43.47%).

Badiuzzaman et al., 2010 conducted a study on 444 quarter milk samples from 111 crossbred dairy cows were subjected to California mastitis test (CMT), somatic cell count (SCC) test, white side test (WST) and surf field mastitis (SFMT) test to quantify their efficacy in detecting sub clinical mastitis in dairy cows of Bangladesh during the period from 2010 to 2011. CMT was concluded to be the most accurate test after cultural isolation and SCC. Unlike laboratory tests as cultural isolation and SCC that require adequate laboratory facilities and skilled personnel, CMT is a reliable diagnostic method in field conditions.

D.C Blood, V.P Studdert et al,concluded  in his study Effective and economic mastitis control programs will rely more and more on prevention rather than treatment. Basic prevention is good control of herd environment and hygiene of milking and use of post-milking teat antisepsis. F.M. Aarestrup, N.E. Jensen et al, concluded in his study The ability of different CNS species to induce a persistent infection, and their associations with milk production, cow milk somatic cell count, lactation number, and month of lactation in cows with subclinical mastitis were studied.In cows with subclinical mastitis, S. epidermidis IMI were mainly found in multiparous cows, whereas S. chromogenes IMI were mainly found in primiparous cows.  T. Clarke et al, in his study apparently contradictory findings are reconciled by noting that infection causes both high strip yields (via uneven yielding quarters) and high SCC. It is concluded that, contrary to popular belief, high SCC, as an indicator of infection, causes high strip yield and that increasing strip yield does not increase cell count.

Rupp et al., in his study found 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. Rupp et al., in his study conclude that Genetic variability of mastitis resistance is well established in dairy genetic correlation among phenotypic traits related to mastitis such as somatic cell counts and clinical cases. The role of Major Histocompatibility Complex in the susceptibility or resistance to intrammamary infection is also well documented. Mastitis also depends upon the genetics of an animal.

Prevalence of Sub Clinical Mastitis

Dua et al, in his study planned to determine the prevalence of sub clinical mastitis in crossbred and indigenous cows and to characterize etiological agent/s involved along with their antimicrobial sensitivity testing. Milk samples from 364 quarters of 95 lactating cows at an organized farm were screened. The overall quarter wise and animal wise prevalence on the basis of cultural examination was 64.21 and 39.83%, respectively. According to International Dairy Federation criteria, 15.38 % quarters of cows  were suffering from sub clinical mastitis on account of having somatic cell count (SCC more than 5,00,000 per ml of milk and culturally positive. The prevalence of latent mastitis (SCC 5 x 105/ml of milk and culturally negative) was observed as 24.45 and 4.67 %, respectively. A total of 150 organisms were recovered out of 145 culturally positive quarters. These were 38.66 % coagulase positive staphylococci and  29.33 % were coagulase negative staphylococci followed by Streptococcus dysgalactiae (22.66%), Streptococcus agalactiae (6.66 %) and Streptococcus uberis (2.66%), and (3.33%) quarters revealed mixed infections  of Staphylococcus spp. and Streptococcus spp. The antibiogram of isolates revealed 100 % sensitivity to Cloxacillin, Ceftriaxone and Cefoperazone and high (90.90-100 %) sensitivity towards Enrofloxacin, Cephalexin, Gentamicin and Lincomycin.

Materials and Method

The study was conducted in the two herds of the Jersey cross-bred dairy cow. The sample was taken from two cattle farm for CMT at the time of milking. Milk samples were taken from 65 animals from FARM -1 and 50 animals from FARM -2. From each cow milk samples were taken from all the four quarters.

Interpretation of California mastitis test

• No slime or gel formation: 0
• Mixture become or gel like: +1
• Mixture distinctly form a gel: +2
• Mixture thickened immediately and tends to form gelly: +3

Data Collection

Group 1- LPM Farm COVAS

Group 2- Jersey Cattle Farm Palampur

Table: 1. Relationship between number of quarters infected and cmt score

Table: 2. Relationship between number of infected cow and cmt score

Table 3. Relationship between parity of infected animals and CMT score

Table 4. Relationship of CMT score with the lactation length

HERD-1

Herd 2

Conclusion

The study indicated that of the 460 quarters analyzed in the two herds of the organized dairy farm, out of which 132 quarters (28.69%) were infected. On the analysis of all quarters, only 1 quarter of udder was more affected in both the herds. Prevalence of CMT score of 1 in Herd 1 and Herd 2 was 45% and 25% respectively. The CMT score was found to increase in the late lactation with the average milk yield of 3.6 Litre in the infected cows. The level of intrammamary infection in dairy cows was more in the first and second parity, which may be due to dairy animals being naïve in the starting lactation to the environmental pathogens.

References

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