J. Vet. Med. B 39, 285-289 (1992) 0 1992 Paul Parey Scientific Publishers, Berlin and Hamburg ISSN 0931- 1793

Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, S-75007 Uppsala, Sweden

Opsonic Activity in Mammary Secretion and Serum of Gilts During the Lactation Period V. T. TSUMA:~ and U. MAGNUSSON Address of authors: Swedish University of Agricultural Sciences, Box 7039, S-75007 Uppsala, Sweden With 2 figures (Receivedf o r publication January 16, 1992)

Summary Opsonic activity was studied in mammary secretion and serum during lactation in four healthy gilts. The opsonic activity was determined as peak chemiluminescence and time to peak chemiluminescence in a luminol enhanced chemiluminescence assay. The peak chemiluminescence was significantly (p < 0.05) higher in mammary secretion around parturition than later in lactation. No changes in the opsonic activity were seen in serum during lactation. Overall, the peak chemiluminescence and time to peak chemiluminescence were significantly higher (p < 0.001) and shorter (p < 0.05) respectively, in serum than in mammary secretion. The present study indicates that the opsonic activity is highest in mammary secretion around parturition but decreases later in lactation, and that this change is confined to the mammary gland. Introduction The occurrence of the agalactia syndrome in sows is limited in time to a few days postpartum. Mastitis affecting one or more mammary glands is a predominant finding in agalactic sows (RINGARP,1960; HERMANSSON et al., 1978; Ross et al., 1981; BACKSTROMet al., 1984). This may imply that there are changes in the immune defence mechanisms in the sow around parturition giving a lowered resistance t o infectious agents. Indeed, there are changes in the number as well as in the functional capacity of circulating blood leucocytes in the sow around parturition (LOFSTEDTet al., 1983; MAGNUSSON and FOSSUM, 1988 and 1990). Also at the site of infection in the agalactia syndrome, i.e., the mammary glands, there are variations in the composition of the mammary secretions in healthy sows with advancement in lactation (EVANSet al., 1982; LEE et al., 1984; SCHOLLENBERGER et al., 1986; MAGNUSSON et al., 1991). In the colostrum, the phagocytic polymorphonuclear leucocyte is the principal cell type, while in milk the number of this type of cell is decreased. The phagocytic polymorphonuclear leucocytes are regarded as being a crucial component in the body’s first line defence against pathogens (MULLER-EBERHARD, 1989). Against this background the opsonic activity, which is an aspect of the immune defence that is essential for efficient phagocytosis, was studied in mammary secretions and serum during lactation. Corresponding author. U.S. Copyright Clearance Center Code Statement:

0931 - 1793/92/3904 -0285$02.50/0

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Material and Methods Animals a n d experimental design Four clinically healthy cross-bred (Swedish Landrace x Swedisch Yorkshire) primiparous SOWS were used in this study. They were housed in individual pens at the Department of Obstetrics and Gynaecology and fed according to the Swedish breeding stock standard. The sows nursed the piglets for 35 days. O n each sampling occasion, mammary secretions were sampled first and then blood was collected. The mammary secretions were collected one day before farrowing, within 16 hours of farrowing, and then 7, 14 and 28 days after farrowing. O n each sampling occasion two mammary secretion samples were taken from each sow from the anterior and posterior teats of the left mammary line. The blood was collected from the jugular vein on the same occasion as for the mammary secretions but was also collected on the 8th day before the expected farrowing time. Blood samples were taken from three of the sows. Sampling of mammary secretions The mammary secretions were collected according to the method described by MAGNUSSON et al. (1991). The piglets were separated from the sow 30 minutes before sampling. The sow was then given 20 I U Oxytocin' by intramuscular injection. The teats were first washed with warm water and soap, then with diluted iodine, and were finally disinfected with ethanol. Each step was repeated three times. Five ml of mammary secretion were collected from each teat by hand-stripping, with the first two streams being discarded. After farrowing only suckled teats were used and those that were sampled prepartum were avoided. The secretions were kept o n ice until centrifugation at 400 x g for 10 minutes. The whey was collected and stored in aliquots of one ml at -70°C until assay. Blood collection About seven ml of blood were collected from the jugular vein in vacutainer tubes without additives. It was kept at room temperature for 30 minutes and then centrifuged. The serum was collected and kept in one ml aliquots and stored at -70°C until assay. Bacteriological examination of the mammary secretions All mammary secretion samples were bacteriologically examined. They were plated o n blood agar (horse blood 5 % v/v) and incubated at 37°C for 24 o r 48 hours before examination. Opsonic activity The opsonic activity in mammary secretions and in serum was determined by a luminolenhanced chemiluminescence (CL) assay, according to the method described for uterine secretions in the mare by MAGNUSSON and JONSSON (1991), with a slight modification for the porcine system. All samples from one mammary line were assayed on the same occasion. In brief, a leucocyte suspension was prepared from the buffy coat from 1Oml heparinized blood, from healthy sows not used for collection of mammary secretion or serum. The cells were suspended in phosphate-buffered saline (PBS) at p H 7.2 and used within one to four hours. For opsonization, 12.5 mg of zymosan2 particles were incubated for 30 minutes at 37°C in one ml of the following solutions: 75 YO mammary secretion and 25 Yo PBS 75 Yo serum and 25 % PBS 75 % pooled sow serum and 25 % PBS 100% PBS

(test sample) (test sample) (standard) (negative control)

The background CL was determined by omitting the zymosan particles. The samples were set up in duplicates. The assay was started by adding 100 PI of the leucocyte suspension per cuvette and by immediately placing the cuvettes in a LKB Luminometer3. The light emission (mV) from the C L was recorded at intervals of 201 seconds until the background CL level was reached after 60 minutes. The peak C L and the time to peak C L were recorded for the determination of the opsonic activity. All the values from the tested mammary secretions and sera were expressed in percent of the values from the standard included in the same assay run. I

2 3

[email protected], Ferrosan, Malmii, Sweden. Sigma, St. Louis, USA. LKB, Bromma, Sweden.

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Statistics In order to compare the opsonic activity in mammary secretions with that in serum, a Student’s t-test for paired comparisons was performed using the Means procedure of the Statistical Analysis System (SAS) (SAS Institute Inc., 1987). To study the variations in opsonic activity over time, an analysis of variance; the GLM-procedure (SAS Inc., 1987), analysing the effect of animal and day of sampling, was used.

Results Bacteriology There was no growth of bacteria in any of the collected mammary secretions. The opsonic activity in mammary secretions and serum during lactation The absolute values of the peak C L and time to peak C L for the standard in the assays ranged between 9.4 to 44.4 mV, and 397 to 1201 seconds respectively. The osponic activity in mammary secretions recorded as peak C L decreased significantly (p

Opsonic activity in mammary secretion and serum of gilts during the lactation period.

Opsonic activity was studied in mammary secretion and serum during lactation in four healthy gilts. The opsonic activity was determined as peak chemil...
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