| In Jiangsu province, the weather in winter was cold, wet and largely different between day and night, the temperature of piglets surface were lower. Pigs in these severe weather conditions with weakened immunity were more susceptible to infectious diseases, such as porcine epidemic diarrhea (PED) or porcine transmissible gastroenteritis (TGE) in winter. Weaning was also a big stress, it reduced the level of circulating antibodies, suppressed cell-mediated immunity, and decreased resistance to disease and pathogenic organisms susceptible, it could also lead to gastrointestinal structural and functional changes. Yeast culture is a mixture of yeast cells, fermented media, and intra-cellar metabolites. Within yeast culture, there were oligosaccharides, amino acids, peptides, proteins, organic acids, vitamins, yeast sourced enzymes and other unknown growth factors. YC could improved the palatability and digestibility of feed and increased the utilization, it also suffered as the main substrates of beneficial bacteria of normal microbiota, stimulated metabolic activity of microorganisms and improved gut microflora environment. This trial was conducted to investigate effects of dietary yeast culture of late gestation sows and nursing piglets on development of intestine, immune function and microbiota of piglets and production performance of sows in winter. This thesis was described in the following three sections:Section1:The experiment was aim to study the effect of yeast culture in sow late gestation and piglet diets on the sow production performance and intestinal development of piglet.48gestating sows were randomly allotted into two groups according to the parities of sows (2-5parities). Control and treatment group all followed the general raising and management strategy of the farm excepting supplementation of2g/kg of XPC yeast culture (YC) in sow diet of treatment group from85days of gestation to weaning. After birth, piglets from control and treatment group were re-allotted to4treatments:1)C0and TO groups (0g YC/kg diet DM);2)C1and T1groups (1g YC/kg diet DM);3)C2and T2groups (2g YC/kg diet DM);4)C4and T4groups (4g YC/kg diet DM). Piglets were weaned at25days of age. All pigs were allowed access to feed and water ad libitum throughout the experiment. At 0,25,35and70days of age, three piglets from C0,C2,T0and T2groups were weighed and slaughtered, tissues of jejunum and ileum were collected for histological analysis. The results showed that:the supplementation of yeast culture significantly improved litter size, weaning number of piglets, litter weight, weaning weight and litter weight gain (P<0.05). Histological result showed that:for Od piglet, ileal villus height, jejunal and ileal crypt depth in yeast culture group were significantly lower than those in control group (P<0.05). But yeast culture remarkably improved villous goblet cell number in the ileum, the villus density of YC group was higher than the control group. For25d piglets, maternal effect significantly increased jejunal villus height, crypt depth and ileal villus height, crypt depth, ratio of villus height and crypt depth (P<0.05), while dietary YC and the interaction of dietary YC and maternal effect remarkably increased ileal villus height, crypt depth. Interaction of dietary YC and maternal effect on crypt goblet cell of jejunum was significant. The ileal villi of TO and T2were stronger than CO and C2, the density of T2was higher than other three groups. For35d piglets, maternal effect significantly improved villus height and the villous goblet cell of ileum(P<0.05), dietary yeast culture significantly increased villus height of jejunum and crypt depth of ileum(P<0.05). Interaction of dietary YC and maternal effect on jejunal and ileal villus height, crypt depth of was significant (P<0.05). Ileal villi of CO and C2were slight atrophy. The villous integrality of TO and T2were visibly better than CO and C2. The villus of T2developed quite well. For70d nursing pig, maternal effect notablely increased ileal villus height, and villus height:crypt depth ratio (P<0.05). Dietary yeast culture significantly improved jejunal villus height and villus height:crypt depth ratio, and ileal villus height (P<0.05). The interaction of dietary YC and maternal effect on jejunal villus height and crypt depth was also remarkable (P<0.05). These was no significant difference on ileal villus height and density among all groups. But the villi of C2and T2were stronger than CO and T0. In conclusion, the supplement of YC improved the reproductive performance of sow, and it also improved the development of intestine in certain degree.Section2:This experiment was conducted to investigate the effect of YC on immune functions of piglets in winter. The experimental design was the same as above. At0,25,35and70days of age, three piglets from C0, C2, T0and T2groups were weighed and slaughtered. Immune organ indices were calculated by weighting thymus, spleen and liver. The level of IFN-γ, IL-4and IL-6in serum, level of S-IgA, IFN-γ, IL-4and IL-6in jejunum and level of IFN-γ, IL-4, IL-6in spleen were tested. The results showed that, at25days of age, maternal effect significantly decreased the index of spleen (P<0.05), there was no remarkable difference on the index of spleen and liver (P>0.05). Maternal effect significantly improved the level of IFN-y in spleen for piglets at0and25days of age (P<0.05). It also notably increased the level of IL-6in jejunum for25d piglet (P<0.05). Dietary yeast culture significantly increased the level of IL-4in serum at35d and decreased the level of IL-4in jejunum mucosa at70d (P<0.05). Interaction of dietary YC and maternal effect on the level of IFN-γ in the jejunum was significant for35d piglets(P<0.05). These indicated that the supplement of YC improved Th-1response. It could enhance immune function of piglet in certain degree, and benefit to the health of piglet in winter.Section3:This experiment was aim to investigate the effect of YC on the composition intestinal microbiota and the numbers of predominant bacteria of piglet. The experimental design was the same as above. At0,25,35and70days of age, three piglets from C0,C2,T0and T2groups weighed and slaughtered, chymus of the ileum and colon were collected for microbiota analysis. PCR/DGGE showed that, the supplement of YC in lactating sow improved the similarities of microbiota structure of the ileum and colon. Before weaning, maternal effect played a leading role, the effect of yeast culture in piglet diet was not obvious. After weaned, the effect of yeast culture in piglet diet was visible. Real-time PCR showed that, the supplement of YC in sow or piglet diet YC had no remarkable effect on the number of total bacteria and lactobacilli for0,25and70d piglet. At35day of age, the supplement of YC in the piglet diet had trend to increase the number of lactobacilli, but had no significant impact on the number of total bacteria. S.suis was detected only in the ileal and colonic chymus of25d piglet, there was no remarkable difference among all groups. In conclusion, the supplement of YC in sow diet changed the structure of piglet intestine tract, there was no significant difference on the number of total bacteria, lactobacilli and S.suis. S.suis was detected only in the ileal and colonic chymus of25d piglet. |
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