Effects Of Dietary Supplementation With Yeast Derivatives On Performance And Immune Function Of Sows And Weaned Piglets

This study was carried out to evaluate the effects of dietary supplementation of yeast derivates (YD) on performance and immune function of weaned piglets and sows as well as the underlying mechanism. The first study was to investigate the effects of yeast extract substituting for spray-dried plasma protein (SDPP) on growth performance, nutrients metabolism and immune function. The second study was to evaluate the effects of supplementing yeast cell wall in sow diet on reproductive performance, milk composition and immune indexes.Experiment 1:The effects of yeast extract substituting for spray-dried plasma protein on growth performance, nutrients metabolism and immune functionA total of 160 PIC weaned piglets (d 28±2,7.35±0.50 kg BW) were randomized into four dietary treatments with five replicates:i) Control, a basal diet; ii) Spray-dried plasma protein (SDPP) diet, basal diet containing 4%SDPP; iii) SDPP plus yeast extract (YE) diet, basal diet containing 2%SDPP and 2%YE; and iv) YE diet, basal diet containing 4%YE. The trial lasted for 28 days; At 08:00 of d 7 and d 28 of the trial, one overnight fast piglet (near average body weight) each replicate was to be collected for blood for the detection of biochemistry metabolism and immune indexes.The resultsGrowth performance:During the first week, the average daily feed intake (ADFI) of piglets fed 4%SDPP or 2%SDPP+2%YE diet was markedly increased than that of piglets fed 4%YE diet (+10～12%, P<0.05). Moreover, the ADFI of piglets fed 4% SDPP diet was significantly increased in contrast with that of piglets fed basal diet (+10%, P<0.05). Compared with the control group, meanwhile, the ADG of piglets fed 2%SDPP+2%YE diet was enhanced prominently (+13%, P<0.05). The results of the whole trial showed that the ADFI of piglets fed 4%SDPP diet was remarkably improved than that of piglets fed basal diet (+11%, P<0.05); During the first week, incidence of scour of piglets fed 4%YE diet was lower than that of piglets fed 4%SDPP diet (0.11 vs 0.25, P<0.05)Metabolism of glucose and lipid:Levels of serum urea nitrogen (SUN) and triglyceride (TG) were significantly decreased in piglets fed diet containing SDPP or YE relative to those of piglets fed basal diet (-16～54%, P<0.05), but the serum levels of total cholesterol, glucose, high density glucolipid-cholesterol and low density glucolipid-cholesterol in weaned piglets had no significant difference among these groups (P>0.05).Immune indexes:On the d 7 and d 28 of the trial, piglets fed diet containing 4%SDPP had higher serum level of IgG compared with fed other diets (+46-60%, P<0.05), but had lower serum level of IgM than fed basal or 2%SDPP+2%YE diet (-15%, P<0.05). However, piglets fed 4%YE diet had lower d 7 serum level of IgM compared with fed other diets (-26～37%, P<0.05), and had lower d 7 or d 28serum level of IgA than fed basal or 2%SDPP+2%YE diet (-28～36%,P<0.05). Despite all this, the d 7 serum level of cortisol related to stress-weaning of piglets fed 4%YE diet was markedly decreased relative to that of piglets fed basal or 2%SDPP+2%YE diet (-32～51%, P<0.05); Serum level of C-reactive protein (CRP) of piglets fed 4% diet was prominently reduced relative to that of piglets fed other diets (-33～55%, P<0.05).Experiment 2:the effects of dietary supplementation of yeast cell wall on reproductive performance, milk composition and immune indexes of sowsEighty PIC sows (parity 3 to 6) were randomly allotted to two dietary treatments according to the parities and body condition scores, receiving basal corn-soybean meal (Control) or basal diet supplemented with 0.2%YCW. The experimental period was from the day of breeding to the weaning day of sows (on the d 21 of lactation). At 08:00 of d 1 and d 90 of gestation and d 1, d 10 and d 21 of lactation, eight fasting sows each treatment was used to be collected for blood samples intravenously from ear. Colostrum and milk samples at d 10 and d 21 of lactation were collected.The resultsReproductive performance:The number of stillborn pigs (-96%, P<0.05) and the occurrence of intrauterine growth retardation (IUGR) pigs (5% vs 11%, P=0.01) were markedly reduced in sows fed YCW relative to sows in control group. Moreover, both body weight and weight gain of pigs tended to improve in YCW group (P<0.10). Accordingly, both litter weight and litter weight gain of sucking pigs were markedly improved in sows fed YCW diet (+10~12%,P=0.05) compared with sows fed basal diet.Milk composition:The concentrations of protein (+5%, P<0.05), non-fat solids (+5%, P<0.05) and lactose (+13%, P<0.01) in milk on d 10 of lactation were significantly increased in sows fed YCW diet compared with sows in control group. Additionally, lactose concentration in milk had an increased tendency on d 21 of lactation in sows fed YCW diet (P=0.08).Immune indexes:The concentrations of IgA, IgM and IgG in both serum and colostrum at farrowing did not markedly differ in the two groups (P>0.05), but feeding YCW diet markedly down-regulated gene expressions of TLR2 (-34%, P=0.05) and IL-1β (-72%, P=0.05) in placental tissue of sows relative to sows in control group, while the placental gene expression of TRAF-6 in sows fed YCW diet tended to decrease (P=0.10).Conclusion1.Diet containing 4%SDPP or 2%SDPP+2%YE is beneficial for growth performance of weaned piglets, which may be ascribed to the improved immune response and the relieved weaning stress after piglets fed SDPP or YE diet.2.Dietary supplementation of 0.2%YCW throughout gestation and lactation markedly reducedthe number of stillbirth and occurrence of IUGR pigs, which may be associated with the better placental innate immunity by 0.2%YCW diet. Meanwhile, feeding 0.2%YCW diet can enhance the growth performance of neonatal piglets via improving milk composition of sows.