A LONG-TERM STUDY ON THE HEALTH-STATUS AND PERFORMANCE OF SOWS ON DIFFERENT FEED ALLOWANCES DURING LATE PREGNANCY .3. ESCHERICHIA-COLI AND OTHER BACTERIA, TOTAL CELL CONTENT, POLYMORPHONUCLEAR LEUKOCYTES AND PH IN COLOSTRUM AND MILK DURING THE FIRST 3 WEEKS OF LACTATION

The objectives of this study were to (1) estimate the clinical status of the mammary glands and (2) compare it with the bacteriological find ings, the total cell content (TCC) and its percentage of polymorphonuc lear leucocytes (PMNLs) and pH in colostrum and milk secretion of sows on 2 different feeding regimes, high versus low, during late pregnanc y. The milk samples were collected from both agalactia post partum (AP P) sows and clinically healthy sows. Sows with a rectal temperature ex ceeding 39.5 degrees C within 48 h after parturition were considered t o be diseased in APP and treated medically. The sows were sampled on d ays 1, 3, 8 and 22 of lactation during 6 consecutive lactations. Irres pective of feeding regimes, 49 out of 77 lactations among the APP sows and 15 out of 96 lactations among the clinically healthy sows reveale d E. coli in pure cultures with a concomitant TCC exceeding 10x10(6) c ell/ml already on the first day of lactation. The healthy sows with E. coli infection were denominated as being subclinically infected sows. The intensity in growth of E. coli successively declined, and the bac teria were finally eliminated between days 3 and 8 of lactation. The T CC were 82x10(6) cells/ml and 157x10(6) cells/ml in the clinically and subclinically E. coli infected glands, respectively, on the first day of sampling. The TCC declined gradually in both groups of sows, but w as still higher than in bacteriologically negative milk on day 22 of l actation. The percentages of PMNLs were 66% and 79% in clinically and subclinically infected glands, respectively, on day 1 of lactation, th ereafter decreasing to approximately 50% on day 22 of lactation in bot h groups of sows. In APP sows, swelling, reddening and/or soreness wer e registered in 38 out of 87 mammary glands with E. coli mastitis on t he first sampling occasion. The TCC in bacteriologically negative colo strum and milk collected from APP sows on day 1 of lactation was signi ficantly higher, 2.27x10(6) cells/ml, when compared with the TCC in ba cteriologically negative milk secretion from the clinically healthy or subclinically infected sows, 1.38x10(6) cells/ml versus 1.51x10(6) ce lls/ml, respectively The PMNLs were higher on day 1 in clinically heal thy sows, 59.6%, than in subclinically infected and APP sows (43.5% an d 48.3% respectively). The pH in secretion from clinically or subclini cally E. coli infected glands (6.57 versus 6.46) were higher than in b acteriologically negative colostrum samples (6.29) from clinically dis eased sows on the first day of sampling. On day 22 of lactation, pH-va lues had stabilized on a level of approximately 7.00 in all milk sampl es from earlier bacteriologically positive or negative mammary glands. The 2 feeding regimes, low versus high, were not found to influence T CC, PMNLs or pH except for TCC in bacteriologically negative samples o f APP sows (2.69 versus 3.62). The lactation number influenced the PMN Ls in both groups of sows with E, coli infected mammary glands, and bo th the TCC and PMNLs in bacteriologically negative colostrum and milk.