Abstract:

The aim of this study was to determine the effects of dietary supplementation with Pennisetum giganteum on the growth performance and intestinal health of finishing Congjiang Xiang pigs. Thirty 6-month-old healthy Congjiang Xiang pigs of similar weight were selected and randomly divided into three groups （five replicates per group， two pigs per replicate）. The control group was fed with a basal diet， and experimental groups Ⅰ and Ⅱ were fed with the basal diet with 10% and 20% （w/w） replaced with fresh P. giganteum. The experimental period was 90 days. The growth performance， intestinal development， and the structures of the intestinal mechanical barrier and cecal flora were analyzed， and the economic benefits were estimated. The main results were as follows： 1） Growth performance： Compared with the control group， groups Ⅰ and Ⅱ showed no significant differences in growth performance or carcass traits （P>0.05）. When the cost of P. giganteum was not considered， groups Ⅰ and Ⅱ had lower weight gain costs （reduced by 8.73% and 11.59%， respectively） than that of the control group. When the cost of P. giganteum was calculated according to the market price of 0.35 CNY·kg^-1， group Ⅰ still had a lower weight gain cost （2.78% lower） than that of the control， but the weight gain cost of experiment group Ⅱ was increased by 1.35%. 2） Intestinal development： Compared with the control group， groups Ⅰ and Ⅱ had significantly higher relative weight of the stomach （P<0.05）， and a trend of higher relative weight of the small intestine （P=0.092）. Compared with the control group， group Ⅰ showed significantly decreased ileal crypt depth （P<0.05）， and significantly increased ileal height/crypt depth （V/C） and transcript levels of GLP-2 in the jejunum and IGF-1R in the ileum （P<0.05）. Compared with the control group， group Ⅱ showed significantly increased ileal villus height， V/C， and gene transcript level of jejunal GLP-2 （P<0.05）. 3） Intestinal immunity and mechanical barriers： Compared with the control group， groups Ⅰ and Ⅱ showed significantly decreased ileal IFN-γ content， and group Ⅱ showed significantly increased jejunal TGF-β content （P<0.05）. Comparing gene transcript levels with those in the control， groups Ⅰ and Ⅱ showed significantly increased transcript levels of ZO-1 in the ileum （P<0.05）， and group Ⅱ showed significantly increased transcript levels of Occludin in the jejunum （P<0.05）. 4） Cecal microbes： Shannon index was significantly higher in both experimental groups than in the control （P<0.05）. The relative abundance of Streptococcus was significantly lower in both experimental groups than in the control （P<0.05）. The experimental groups showed trends of increased abundance of unclassified_f__Lachnospiraceae （P=0.065） and decreased abundance of Spirochaetota （P=0.085） and Treponema （P=0.085）. In conclusion， replacing part of the basal diet with P. giganteum had no significant effect on the growth performance or carcass traits of finishing Congjiang Xiang pigs， but it improved the economic efficiency， promoted gastrointestinal tract development， and enhanced intestinal barrier function， which were conducive to intestinal health. These results show that 20% of the basal diet can be replaced with P. giganteum if its cost is not considered， and 10% of the basal diet can be replaced with P. giganteum if it is costed at the market price of 0.35 CNY·kg^-1. These findings provide scientific data for assessing the application of P. giganteum in pig production.

Key words: Pennisetum giganteum, finishing Congjiang Xiang pigs, growth performance, cecal microflora, intestinal health