Effects Of Immunostimulants On The Health Status Of Sows And Their Suckling Piglets

The purpose of this experiment was to estimate the effects of reproduction performance of sows, the composition of colostrum or milk, growth performance of piglets, immune fuction of sows and their piglets with immunostimulants added to sows diets during late gestation and lactation. The40crossbred pregnant sows (Large white×Landrace) were divided randomly into four groups of ten accounting for parity (3-6parity) and expected delivery date. Group Ⅰ was served as a control, group Ⅱ received350mg/kg β-glucans, group Ⅲ received2000mg/kg HMB (β-hydroxy-β-methylbutyrate) and group Ⅳ received15mg/kg daidzein. The experiment was from day74of gestation to day21after birth of piglets.1Effects of immunostimulants on reproduction performance of sows, composition of colostrum or milk, and growth performance of piglets.(1) There were no significant differences on reproduction performance of sows by adding β-glucan, HMB or daidzein to sows diets during late gestation and lactation (P>0.05), and backfat change had no significant differences from day0of lactation to weaning (P>0.05).(2) Colostrum fat and solids-not-fat, milk protein and fat on day21of lactation were highly significantly increased with dietary β-glucan supplementation (P<0.01), and colostrum protein and milk fat on day7were significantly increased (P<0.05).(3) Litter weaning weight and piglet weaning weight were increased significantly by the addition of HMB to sows diets (P<0.05), and daidzein supplementation led to increasing litter weaning weight (P<0.05).2Effects of immunostimulants on immune fuction of sows and their piglets(1) The concentration of immunoglobulin and lysozyme of sows serum:The serum concentration of IgG on day98of gestation in sows fed β-glucan was increased significantly (P<0.01), and the concentration of IgG on day0of lactation, the concentration of IgM in the whole experiment period (day98of gestation, day0and14of lactation) were increased significantly (P<0.05). Compared with the control group, dietary HMB supplementation led to a signigicantly higher serum IgG concentration on day98of gestation (P<0.01), and the concentration of IgM on day98of gestation was higher (P<0.05). The daidzein supplemented sows had a significantly higher IgM concentration on day98of gestation (P<0.01). The concentration of lysozyme on day0of lactation was increased significantly by feeding β-glucans (P<0.05).(2) The concentrations of immunoglobulin and lysozyme of sows colostrum or milk: compared with control group, β-glucans supplementation resulted in significantly higher colostrum IgA and IgG concentrations (P<0.05), higher milk IgA, IgG and IgM concentrations on day7of lactation (P<0.05), and a higher milk IgM concentration on day14(P<0.05). Milk IgM on day14of lactation was increased significantly in response to feeding HMB (P<0.05). Dietary supplementation with daidzein significantly increased the IgA and IgG concentrations of colostrums (P<0.05). Milk IgA on day14of lactation was increased significantly (P<0.05), and milk IgM concentration was significantly higher compared with control group (P<0.01). The concentration of colostrum lysozyme was unaffected by the treatment (P>0.05).(3) The concentration of plasma immunoglobulin of piglets:In the piglets sucking the β-glucan supplemented sows, the concentration of plasma IgG were enhanced significantly on days7,14and21of lactation (P<0.05), plasma IgM were increased significantly on days14and21of lactation (P<0.05). Piglets plasma IgM and IgG in HMB supplementation group were higher than control group on day7of lactation (P<0.05). Dietary supplementation of daidzein to sows increased the plasma IgM concentration of their piglets on days7and14of lacation (P<0.05).3Mechanism of immune regulation(1) The percentage of peripheral blood CD8+T cells on day98of gestation could be decreased by β-glucan or daidzein supplementation (P<0.05), but their ratio of CD4+/CD8+were unaffected (P>0.05). Compared with control group, HMR supplementation groups had no significant differences on CD4+, CD8+, CD4+CD8+, CD4+CD25+, CD4+/CD8+(P>0.05).HMB supplementation group showed higher percentage of peripheral blood CD8+T cells on day14of lactation (P<0.05), but the ratio of CD4+/CD8+had no difference (P>0.05). Lymphocyte subpopulations were unaffected by dietary β-glucan or daidzein supplementation (P>0.05).(2) Dietary β-glucan, HMB or daidzein supplementation did not significantly influence serum INF-γ and IL-4concentrations of sows on day98of gestation and day14of lacation (P>0.05).(3) Immunostimulants influenced the activity of peripheral blood lymphocyte proliferation in vitro, β-glucan could enchance the lymphocyte proliferation induced by ConA significantly more than control group at high (400μg/mL) and middle (100μg/mL) concentrations (P<0.05). HMB caused a significantly higher lymphocyte proliferation induced by ConA at high (100μg/mL) concentration (P<0.05). Daidzein resulted in significantly higher lymphocyte proliferation induced by ConA at concentrations of10ng/mL,50ng/mL and100ng/mL.β-glucan, HMB and daidzein significantly enhanced the lymphocyte proliferation induced by LPS at high concentration (P<0.05), but they could not enhance the lymphocyte proliferation induced by LPS at low and middle concentrations (P>0.05).Conclusion:(1) Immune fuction of sows was enchanced by the addition of immunostimulants (β-glucan, HMB or daidzein) to sows diets during late gestation and lactation, and the immune substances of colostrum or milk were increased, immune function of piglets was, therefore, enhanced by sucking colostrum and milk.(2) Suitable concentrations of β-glucan, HMB or daidzein could enhance the lymphocyte proliferation induced by ConA or LPS.