DHI: Somatic Cell Counts - AgroMedia

1 SOMATICCELL COUNTS2 Objectives of the Somatic Cell count option to evaluate the udder health of all individual cows in the herd to determine the level of mastitis in the herd to aid in the detection and control of subclinical mastitis to evaluate the effectiveness of the mastitis control program to predict the milk loss associated with mastitis, for each cow andfor the herd to summarize current and historical individual cow Somatic cellcount information to provide an analysis of Somatic cell count (SCC) data in terms oftrends in herd average SCCs, the effect of age on SCCs, and theeffect of stage of lactation on Cow Report objectives to provide current individual cow udder health information andtrends.

2 In terms of SCC and linear score results for the last 6 testdates to provide the current contributions made by individual cows tothe herd average SCC to provide historical information on the udder health of individualcows through lactation and lifetime average linear scores to estimate the current lactation milk loss in dollars for eachindividual cowHerd Summary Report objectivesHERD Somatic CELL count TEST DAY SUMMARY to detect herd trends in terms of the number of cows with nomastitis infections, new infections and chronic infections to evaluate the effectiveness of the mastitis control program interms of herd average SCC, bulk tank SCC, herd average linearscore and herd milk loss in dollarsAGE SUMMARY to determine the effect of lactation number on the distribution ofuninfected and infected cows in the herdSTAGE OF LACTATION SUMMARY to determine the effect of stage of lactation on the distribution ofuninfected and infected cows in the herdSOMATIC CELL count PROBLEM COW LIST to list the cows making the greatest contribution to the herdaverage SCC to identify cows with possible new and/or chronic infectionsDHI Somatic Cell Counts 3 Individual Cow Report checklist3 Are the CURRENT TEST DAY SCC results higher or lower than thosefor the PREVIOUS 5 TESTS?

3 3 Is there a correlation between DAYS IN milk (DIM) and SCC?By reviewing DIM and SCC are there any trends?3 Which cows are uninfected? These would most likely be the cows with aLINEAR SCORE (LS) below Which cows have chronic mastitis (at least two consecutive test day LSresults over )? What are the LACTATION AVERAGE and LIFETIMEAVERAGE LINEAR SCORES of these cows?3 Are the LINEAR SCORES for all 1st lactation animals below What are the SCC results for fresh cows? Is the dry cow treatmentprogram working, or is there a problem with infections during calving orin early lactation?3 Which cows should be considered for milk culturing?3 What are the SCC results for cows treated since the last test?

4 Are thesecows cured? milk culturing may be required to determine the infectionstatus of these Are there cows that should be dried off early because of a high SCCresult?3 Should the milking order of the cows be changed? Should any cowsfrom an uninfected group be moved to the infected group?3 Which cows made the greatest % CONTRIBUTION TO HERD AVE SCC?How much milk are these cows producing? What is the CURRENTLACTATION milk LOSS $ for these cows? What are their BCAdeviations on the Cow Production Monthly Report? Do they have chronicmastitis? Should some of them be culled?4 Explanation and interpretation of Individual Cow Report outputThis report provides information on the udder health of individual cowson test day, during the current lactation and over the cow s lifetime.

5 Anelevated SCC for a cow suggests a bacterial infection in one or morequarters. Although milk may appear normal, udder tissue damage andsignificant milk losses are taking AND TEST DAY INFORMATIONThe four boxes in the top left hand corner of the Somatic CellCount Individual Cow Report show the HERD #, TEST DATE,MAIL DATE of the report and the SERVICE LEVEL in which theherd is enrolled. All individual cow information on this reportreflects the situation as of the TEST DATE shown cows in the herd (milking, dry and cows which left the herd at lasttest) are listed in the body of the SCC Individual Cow Report. The reportis divided into 5 sections : COW IDENTIFICATION; CURRENT TEST DAY; PREVIOUS 5 TESTS; LINEAR SCORES, and; CURRENT LACTATION milk LOSS $.

6 COW IDENTIFICATIONCows may be identified by their chain number, registration number, cowname or a combination of any 2 of these methods. The order in whichcows are listed may be chosen by the producer to suit the herd smanagement. Cows may be listed : alphabetically by cow name; numerically by chain number; by age of aid in cross-referencing production and SCC information, it may behelpful to have cows listed in the same order as on the Cow ProductionMonthly TEST DAYThis section provides information on the udder health status of cowson the current test day. For each cow, it lists : DAYS IN milk ; LACTATION NUMBER; Somatic CELL count ; LINEAR SCORE, and;. % CONTRIBUTION TO HERD AVERAGE Somatic Somatic Cell Counts 5 DAYS IN milk is the number of days from the last calving date (listed onthe Cow Production Monthly Report) to the current TEST cows less than 5 DIM, the code TOO FRSH (too fresh) appears in theSCC (x 1000) column.

7 In the first two weeks post-calving, there may bea natural elevation of the SCC in the milk . However, current researchindicates that an elevated SCC in this period may also be caused bycoliform infections picked up at calving. Later in lactation, SCC does notincrease significantly in uninfected quarters. An increase in SCC or LS atthis time is more than likely caused by an NUMBER is the current lactation of the cow on are not influenced by the number of lactations, although they arehigher in older cows. As cows age, there is an increased risk of exposureto mastitis pathogens. This can result in a gradual increase in the numberof infected quarters. Older cows tend to have infections of longerduration, causing more extensive tissue Somatic cell count (printed in 000s of cells / ml) is an indication ofthe test day milk quality and of udder health.

8 The message DRY occurswhen the cow is in her dry period. The TOO FRSH (too fresh) codeappears if the cow is less than 5 days fresh on test day. NO TEST isprinted if the test day sample was not available or not tested. SOLD orDIED appears if the cow has left the herd since the last test. The use ofindividual cow SCCs in making management decisions is described onpage threshold value of SCC must be established to differentiate betweeninfected and uninfected cows. However, using a threshold value willresult in some infected cows being inaccurately labelled uninfected andsome uninfected cows being labelled infected (see figure 1). Researchsuggests that the best SCC threshold value is 200,000 cells /ml.

9 Using thisvalue, approximately85% of cows infectedwith mastitis causingbacteria are correctlyidentified as infectedand, conversely, 85%of uninfected cows arecorrectly identified 1 : About 15%of infected cows mayhave SCCs below200,000 cells /ml; anequal proportion ofnon-infected cowsmay have SCCs abovethis SCORE (LS) is calculated from the Somatic cell count . Therelationship between LS and SCC is shown in table cell Counts increase with the severity of udder infection. However,the corresponding milk loss does not increase at the same rate. The use oflinear scores simplifies the prediction of milk loss. For each doubling of theSCC the LS increases by one. For 2nd lactation and older cows, each LS unitincrease above LS equals a loss of 200 kg of milk per lactation or of milk per day.

10 The milk yield loss of first lactation animals isestimated to be one half that of older cows as shown in figure 2 : Lactationmilk loss chart bylinear SCORE (tenths) Somatic CELL Counts ( x 1000 ) ------------------------------0 1213 1415161819 20 22 231 2527 2931333538 41 44 472 5054 5762667176 81 87 933100 107 115 123 132 141 1521621741874200 214 230 246 264 283 3033253483735400 429 459 492 528 566 6066506967466800 857 919 985 1056 1131 1213 1300 1393 149371600 1715 1838 1970 2111 2263 2425 2599 2786 298683200 3430 3676 3940 4222 4525 4850 5198 5572 597196400 6859 7352 7879 8445 9051 9701 10397 11143 11943 LINEARSCORE(units)Figure 2.