京仁地域에 사육중인 젖소의 原乳중 體細胞의 變動에 관한 연구

Studies on variation of somatic cell counts for raw milk of dairy cattle in Kyeong-In area

Somatic cell counts(SCC) were performed from 3,479 quarter milk samples in 3 herds by Fossomatic ’90 from January 1990 to December 1991 in Kyeong-In area. At the same time, 15,697milk samples from 8,366 heads collected from 6 or 7 different districts were tested for SCC bimonthly. The results obtained are summarized as follows : 1. Evaluation of SCC of 3,479 quarter milk tested during two years revealed that 56.7% was less than 200×10³ cells/ml, 17.1% between 201 and 500×10³ cells/ml, 12.3% between 501 and 1,250×10³ cells/ml and 13.9% more than 1,251×10³ cells/ml. 2. Distribution of 1,607 quarter milk tested in 1990, showed that 66.9% was less than 200×10³ cells/ml, 12.2% between 201 and 500×10³ cells/ml, 10.5% between 501 and 1,250×10³ cells/ml 10.5% more than 1,251×10³ cells/ml. In 1991, 1,872 quarter milk samples were tested for SCC. Among them, 47.5% was less then 200×10³ cells/ml, 21.3% between 201 and 500×10³ cells/ml, 14.6% between 501 and 1,250×10³ cells/ml, and 16.7% more than 1,251×10³ cells/ml. Average SCC in 1990 was higher than those in 1991 significantly(p＜0.01). The ratio of first grade milk in 1990 was higher in fore quarters than in hind quarters(p＜0.05). In 1991, the significant differences were formd in case of the average SCC was less than 200×10³ cells/ml(p＜0.05). 3. Variations of average SCC in the quarter milk showed the higher prevalence in April of 1990, and in September, October and November of 1991. The period of increment of the quarter milk SCC was coincident with the period of mastitis outbreaks in the herds. 4. The average SCC of 8,725 herd milk from 4,514 farms examined in 1990 were 373×10³ cells/ml, showing the lower counts in February, March and April and the higher counts in August and September. The arerage SCC of 6,972 herd milk from 3,852 farns tested in 1991 was 518x10³ cells/ml showing the lower counts from January to April, and the higher counts in June and August. 5. The variation of average SCC of 15, you herd milk in two years showed that 33.4% was less than 200×10³ cells/ml, 42.1% between 201 and 500×10³ cells/ml, 19.4% between 501-1,250x10³ cells/ml and 5.0% anmore than 1,251×10³ cells/ml. 6. In 1990, the variation of average SCC of 8,725 herd milk showed that 39.3% was less than 200×10³ cells/ml, 41.5% between 201 and 500×10³ cells/ml and 15.8% between 501 and 1,250×10³ cells/ml and 3.4% more than 1,251×10³ cells/ml. In 1991, the variation of average SCC of 6,972 herd milk showed that 26.1% was less than 200×10³ cells/ml, 42.8% between 201 and 500×10³ cells/ml, 24.0% between 501 and 1,251×10³ cells/ml and 7.1% more than 1,251×10³ cells/ml. The average SCC in 1991 was higher than that in 1990 significantly(P＜0.01).