| The study was conducted to investigate the effects of dietary fiber levels on reproductive performance of sows and explored the intrinsic mechanism. Thirty-seven cross bred (Landrace × Yorkshire) gilts with similar parity and body condition were randomly allocated to two groups. Once weaned, sows were feed low fiber diet (Low fiber diet, LF, N= 16) and high fiber diets (High fiber diet, HF, N= 21). The study investigated:(1) The effects of dietary fiber levels on reproductive performance, nutrient digestibility, rectum short chain fatty acids (SCFAs) composition and concentration, rectum lipopolysaccharide (LPS) concentration of sows; (2) The effects of dietary fiber levels on rectum microorganism of sows.1 Effects of crude fiber on reproductive performance, rectum SCFAs and LPS of sows1.1 Reproductive performanceHF significantly improved litter size (15.29 vs 12.38; P= 0.007), alive litter size (14.05 vs 11.62; P= 0.02) and birth litter weight (21.28 vs 17.20; P= 0.004) of sows compared with LF group. There were no remarked differences in weaning to estrus interval and average birth weight between HF group and LF group.1.2 Nutrient digestibilityHF group had lower apparent digestibility of dry matter (86.76 vs 90.57,83.18 vs 89.06; P=0.000), crude protein (83.23 vs 89.51,80.20 vs 89.24; P=0.000), ash (41.11 vs 55.36,36.00 vs 48.84; P=0.000), but had higher crude fiber apparent digestibility (66.31 vs 59.15,57.87 vs 48.10; P=0.001,0.000) compared with the LF group on gestation 30d and 90d, while HF significantly reduced the apparent utilization of Ca (31.10 vs 37.63,26.13vs 41.26;P=0.040,0.000) and P (36.07 vs 65.42,32.64 vs 57.53; P=0.000).On gestation 30d, HF group had higher apparent digestibility of dry matter, crude protein, crude fat, ash and crude fiber than gestation 90d (P= 0.000,0.000,0.000,0.024, 0.000), while there were no remarkable difference in apparent utilization of Ca and P. For LF group, the apparent digestibility of dry matter, crude fat, ash, crude fiber and P on gestation 30d were higher than that of on the gestation 90d (P= 0.000,0.000,0.001,0.000, 0.036).1.3 The composition and concentration of SCFAsOn gestation 30d, in contrast to LF group, HF can significantly improved the concentration of acetic acid, propionic acid, isobutyric acid, butyric acid and total acid (P= 0.003,0.016,0.002,0.002,0.016), but no changes were found in the valeric acid and isovaleric acid concentration; on gestation 90d, HF group had higher concentration of acetic acid, propionic acid, isobutyric acid, butyric acid, valeric acid, isovaleric acid and total acid (P= 0.000).In contrast to gestation 90d, LF significantly improved the concentration of acetic acid, propionic acid, isobutyric acid, isovaleric acid and total acid on gestation 30d (P= 0.000、 0.003,0.000,0.027,0.000), while HF had higher concentration of acetic acid, isobutyric acid and total acid (P= 0.000,0.001,0.000).On gestation 30d, there were no correlation between total acid concentration and litter size, alive litter size and birth litter weigh; on gestation 90d, moderate positive correlation were found between litter size and acetic acid, propionic acid, isobutyric acid, butyric acid, valeric acid, isovaleric acid and total acid concentration (r= 0.36,0.38,0.34,0.33, 0.44,0.38; P= 0.029,0.019,0.038,0.044,0.006,0.019), alive litter size and acetic acid, propionic acid, valeric acid, total acid concentration (r= 0.38,0.36,0.37,0.38; P= 0.019, 0.028,0.025,0.021).1.4 LPSHF significantly decreased the concentration of LPS in rectum of sows on gestation 30d and 90d (P= 0.037); while the concentration of LPS on gestation 30d was lower than gestation 90d(P= 0.011).2 Effects of crude fiber on rectum microorganismIn contrast with LF group, HF significantly decreased the number of total bacteria on gestation 30d (P= 0.045) and significantly reduced the number of total bacteria and lactobacilli on gestation 90d (P=0.000,0.008); there were no remarkable difference in the number of enterobacteria between LF group and HF group during the whole regnancy cycle.The number of total bacteria, lactobacilli and enterobacteria was varied along the different physiological stages of sows. The number of total bacteria in HF group on gestation 30d was the least and on lactation 20d reached the peak, while the number of total bacteria was on the rise between the two stages. The number of total bacteria on pregnancy 60d was significantly higher than that of pregnancy 30d (P= 0.047).In addition, there was no significant difference between pregnancy 60d and 90d, while pregnancy 120d were significantly higher than pregnancy 90d (P= 0.016), lactation 20d were significantly higher than pregnancy 120d (P= 0.001) and post weaning 5d (P= 0.000), post weaning 5d was significantly higher than pregnancy 30d (P= 0.000); The number of enterobacteria increased from pregnancy 30d to pregnancy 90d and pregnancy 90d to post weaning 5d first decreased and then increased and then decreased, pregnancy 60d was remarkable higher than pregnancy 30d (P= 0.000), there was no significantly difference between pregnancy 90d and pregnancy 60d and pregnancy 120d. Beyond that, lactation 20d was significantly higher than pregnancy 120d (P= 0.037) and after weaning 5d (P= 0.025); The number of lactobacilli was decreasing from pregnancy 30d to pregnancy 120d, and then increased to the peak on lactation 20d. There was no remarkable difference between pregnancy 30d to pregnancy 120d, while lactation 20d was significantly higher than pregnancy 120d (P=0.002) and after weaning 5d(P= 0.004).Conclusion:(1) The crude fiber levels could influence the feed utilization, reproduction performance, and rectum SCFAs and LPS content. In addition, moderate positive correlation were found between litter alive size and SCFAs concentration; (2) The effect of crude fiber levels on rectum microorganism was depended on gestation period. |
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