A LONG-TERM STUDY ON THE HEALTH-STATUS AND PERFORMANCE OF SOWS ON DIFFERENT FEED ALLOWANCES DURING LATE PREGNANCY .2. THE TOTAL CELL CONTENT AND ITS PERCENTAGE OF POLYMORPHONUCLEAR LEUKOCYTES IN PATHOGEN-FREE COLOSTRUM AND MILK COLLECTED FROM CLINICALLY HEALTHY SOWS

The main objective of this study was to determine the total cell conte nt, TCC, and the percentage of polymorphonuclear leucocytes, PMNLs, in colostrum and milk collected from sows during the first 22 days of la ctation. The pH-values during the same sampling period were also deter mined. It should be emphasized that all the values obtained emanate fr om bacteriologically negative colostrum and milk. The potential influe nce of different levels of late gestation feeding regimes was also eva luated. The TCC-Values obtained from milk samples during the first 3 w eeks of lactation and exceeding the designated threshold of 10x10(6) c ells/ml varied between 4% and 21%. Within the TCC-limitation of 10-19. 99x10(6) cells/ml neither the preceding nor the succeeding cell counts exceeded the threshold in 26.8%. TCC-values above 19.99x10(6) cells/m l were preceded and succeeded by cell counts below the threshold in 58 .8% and 58.8%, respectively. The TCC-levels below the threshold of 10x 10(6) cells/ml, expressed as geometric least square means, increased s ignificantly from day 1 to day 3 (1.23x10(6) cells/ml versus 1.86x10(6 ) cells/ml) and decreased thereafter gradually to day 22 (1.38x10(6) c ells/ml). When all values were included the TCC-values increased in a similar pattern from day 1 to day 3 (1.38x10(6) cells/ml versus 3.18x1 0(6) cells/ml). The Value on day 22 of lactation was still on a signif icantly elevated level compared with that of day 1 (2.10x10(6) cells/m l versus 1.38x10(6) cells/ml). The 2 different feeding regimes were no t found to influence the TCC-values during the first 22 days of lactat ion. In the whole material the PMNL-values, expressed as percentages o f the TCC, declined from approximately 60% on day 1 of lactation to be tween 40% and 50% for the remaining sampling period. This decline was comparable with the one seen in the cell class below the threshold of 10x10(6) cells/ml. In the 2 cell classes above 9.99x10(6) cells/ml, 78 .0% and 88.8% of PMNLs on day 1 declined to about 40% on day 22. This might indicate an inflammatory response on day 1 but without any detec table bacteriological growth. The increase in lactation number, if lac tation 1 was compared with the following lactations, revealed a signif icant rise (p<0.05) in TCC-level and percentage level of PMNLs. A step wise and significant increase in pH-level occurred between days 1, 3 a nd 8 (6.18, 6.56, 7.03) followed by a significant decrease to day 22 ( 6.91) when pH-values from milk of all cell classes were included.