Mastitis

Case study Happy Dreams Dairy
Happy Dreams Dairy is a small dairy farm in upstate New York. They are currently milking 34 cows in a tie-stall with a round the barn pipeline. Stalls are clean and sawdust is used for bedding and cleaned twice a day. The owner wants to try and get his Bulk Milk cell count below 150,000 to obtain the maximum premium from his milk buyer ($0.75 per cwt). There is asingle person (the owner) milking the cows at 6:45 am and pm. Preparation before milking consists of dipping with 1% iodine dip, wipe and attach. Post milking teat disinfection is with Uddergold®. The owner always wears gloves and is very conscious about cow cleanliness. The herd has very few cases of clinical mastitis (the owner only recalls two cases in the last year). Cow nr 60 had mastitisshortly after calving and was treated by the veterinarian with an antibiotic, Cow nr 18 had mastitis about 4 months ago and was not treated. Replacements (mostly springing heifers) are purchased and cultured before added to the milking herd. Current average Cell count and linear score of the herd are shown below:

A list of all linear scores of the last four test days (7/30, 8/26, 9/30 and 10/28)is shown in the table below. The whole herd was cultured on November 1st and the culture results are shown under the column name RCULT. Other columns show FDAT for fresh date, LACT for lactation, DIM for days in Milk, and then the 4 SCC and LS values (PSCC4, PSCC3, PSCC, SCC and PLS4 PLS3 PLS AND LS) and 3 for milk production (PMIL3 PMILK and MILK).

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7/30/07
BNAME 2 6 7 8 12 16 17 18 2030 31 35 37 38 39 40 41 42 44 47 48 51 53 55 56 60 61 FLOSSY 63 143 146 JC 417 PALMA Average Total FDAT LACT 2/18/07 1 3/14/07 1 3/ 4/07 1 8/14/07 2 9/ 1/07 1 6/20/07 1 8/12/07 3 3/ 2/07 1 6/26/07 2 11/11/06 2 12/20/06 1 8/ 8/06 3 4/21/07 4 8/13/06 1 5/28/07 4 6/11/07 4 7/31/06 1 10/29/06 3 10/16/07 2 9/16/07 4 10/9/07 2 9/27/07 4 8/26/07 2 7/17/06 3 12/29/06 3 8/19/07 3 1/22/07 1 11/29/06 112/22/06 1 3/ 6/07 1 3/24/07 1 4/12/07 1 10/26/07 2 7/13/07 1 2 DIM 275 251 261 98 80 153 100 263 147 374 335 469 213 464 176 162 477 387 35 65 42 54 86 491 326 93 302 356 333 259 241 222 25 130 228 PSCC4 650 123 31 283 0 35 246 460 25 76 22 152 47 29 162 174 81 123 0 0 0 0 0 50 62 0 162 31 18 44 25 2786 0 174 PLS4 5.7 3.3 1.3 4.4 0 1.4 4.3 5.2 1 2.6 0.8 3.6 1.9 1.2 3.7 3.8 2.7 3.3 0 0 0 0 0 2 2.3 03.7 1.3 0.5 1.8 1 7.8 0 3.8

8/26/07
PSCC3 492 66 13 71 15 13 27 214 14 57 19 141 50 31 123 325 57 71 0 174 0 0 23 31 20 5572 33 31 14 15 14 29 0 50 PLS3 PMIL3 5.3 41 2.4 54 0.1 43 2.4 70 0.3 53 0.1 60 1.1 74 4.1 62 0.2 94 2.2 54 0.6 59 3.4 34 2 39 1.3 50 3.3 45 4.7 93 2.2 45 2.4 47 0 0 3.8 51 0 0 0 0 0.9 75 1.3 73 0.7 48 8.8 77 1.4 85 1.3 52 0.2 79 0.3 58 0.2 67 1.2 53 0 0 2 50 60 18009/30/07
PSCC 152 76 13 152 13 0 107 373 31 93 33 214 54 54 187 400 152 81 41 566 22 22 54 29 27 31 18 38 13 20 29 22 0 57 PLS PMILK 3.6 36 2.6 46 0.1 49 3.6 60 0.1 55 0 54 3.1 63 4.9 52 1.3 84 2.9 32 1.4 43 4.1 29 2.1 38 2.1 33 3.9 34 5 66 3.6 26 2.7 46 1.7 59 5.4 57 0.8 58 0.8 94 2.1 63 1.2 44 1.1 34 1.3 76 0.5 52 1.6 43 0.1 47 0.7 54 1.2 48 0.8 40 0 0 2.2 49 50 1650

10/28/07
LS 3.4 3.7 1.11.3 0.1 0.6 3.4 5.7 2.2 3.7 2.6 3.4 2.1 3.8 4.1 5.4 3 3.4 1.4 5.3 0.8 0.1 1.6 1.2 0.8 1.2 0.1 2.2 0.2 1 1.2 2.4 0.8 0.6 SCC MILK RCULT 132 34 AUREUS 162 35 CNS 27 47 NEG 31 67 STREP 13 52 NEG 19 53 NEG 132 46 NEG 650 48 AUREUS 57 81 NEG 162 29 STREP 76 37 NEG 132 30 NEG 54 43 NEG 174 14 NEG 214 39 CNS 528 63 CNS 100 19 NEG 132 36 NEG 33 66 NEG 492 46 YEAST 22 64 NEG 13 95 NEG 38 56 NEG 29 50 CNS 2234 NEG 29 73 NEG 13 52 NEG 57 39 NEG 14 39 NEG 25 39 NEG 29 36 NEG 71 39 NEG 22 64 NEG 19 58 NEG 48 1632

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The graph below shows a scatter plot of the last and previous linear score

Questions: 1. The owner does not understand the spike in SCC on 8/26. The average cell count was 370,000 at that time and 98,000 and 105,000 on the next two test days. Can you explain this ? Calculate the...