Impact of a long photoperiod during lactation on immune status of piglets1

Abstract

The effects of a long photoperiod treatment around parturition and throughout lactation on immune status of piglets were studied. Sows were assigned to 2 light regimens: i) standard short photoperiod (SP, n = 17), 8 h of daily light from d 112 of gestation until d 23 of lactation; and ii) long photoperiod (LP, n = 17), 23 h of daily light from d 112 of gestation to d 4 of lactation and 16 h thereafter. In front of the crates, under the side heat lamps and behind the sow, light intensities were 59 ± 5, 109 ± 6, and 44 ± 6 lx, respectively. On d 15 of lactation and at weaning (d 23), 2 piglets of similar BW per litter were selected and immunized intramuscularly with ovalbumin (OVA). Blood samples (5 mL serum and 10 mL whole blood) were taken at d 15 and d 23 of lactation, and at d 30, 37, and 44 of age after weaning to evaluate the antibody response to OVA and measure phagocytosis, lymphocyte proliferative response, and different circulating blood lymphocyte populations of piglets. Results showed that phagocytosis was increased in piglets submitted to LP (P < 0.05). A treatment × time interaction (P < 0.001) indicated that SP piglets developed a better IgG response to OVA than LP piglets. The percentage of B lymphocytes was also increased (P = 0.02) in SP piglets compared with piglets exposed to LP during lactation; the lymphocyte response to OVA tended to be enhanced (P = 0.07) over time in SP piglets. Different subpopulations of CD8+ lymphocytes were markedly increased in SP piglets at 23 d of age compared with piglets exposed to LP (treatment × time: P < 0.05). These results suggest that exposure of piglets to LP during lactation seems to reduce the capacity of piglets to develop a strong immune response to novel antigens. This may have important consequences on the ability of piglets to resist an infection after weaning.

Homocysteine metabolism, growth performance, and immune responses in suckling and weanling piglets1

“…The piglets were immunized twice, at 14 and 28 d of age with 0.5 mL of a solution containing 2 mg/mL of ovalbumin (OVA) and 2 mg/mL of QuilA emulsified with 0.5 mL of incomplete Freund adjuvant as described previously by Lessard et al (2012). Blood samples were collected in non-coated tubes (10 mL; Becton Dickinson) before the first immunization and at 21, 28, 35, 42, 49, and 56 d of age.…”

“…Antibody response to OVA of immunized piglets was measured by ELISA as described previously (Lessard et al 2012). For the measurement of the inflammatory markers interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) in serum, commercial ELISA kits were used (Life Technologies, Burlington, ON, Canada).…”

Development of leukocytes countin blood of neonatal pigs after colostrum intake

“…Numbers of leukocytes change with age after birth. This may have important consequences on the ability of piglets resist an infection (Lessard et al, 2012). Harvey (2012) published reference interval for total white blood cells from 15.6 to 38.9 G*l -1 for healthy adult pigs of both sexes and various breeds.…”

Neuroendocrine control of photoperiodic changes in immune function

“…Melatonin implants also act on the SCN to reduce sickness behavior in Siberian hamsters (Freeman et al ., 2007). In Syrian hamsters ( Mesocricetus auratus ), melatonin augments humoral and cell-mediated immune responses following dexamethasone-induced stress (Vishwas et al ., 2013) and short photoperiods increase IgG responses to ovalbumin in piglets (Lessard et al ., 2012). Photoperiodic modulation of immune function may be accomplished not only through alterations in melatonin secretion, but sensitivity to the melatonin signal via changes in receptor expression.…”