| Transportation stress often leads to oxidative stress in animal organism,which damages intestinal structure and reduces intestinal digestive function,thus affecting livestock and poultry production performance and bringing economic loss to the farming industry.As an alkaline ionic compound feed additive,IAMC plays a significant role in improving metabolism and production performance of cultured animals.However,the research on the effect of IAMC on the digestive function of the intestinal tract of animals under transport stress is not perfect.Therefore,this experiment investigated the effects of IAMC on growth performance,apparent digestibility of diet,intestinal digestive enzymes and intestinal flora diversity in rats under transport stress,and further promoted the application of IAMC in the prevention and control of transport stress in livestock and poultry.There were five time points in this experiment,namely three days before transportation(D-3),Before carriage(D0),After delivery(D0+),the third day after transportation(D3),and the tenth day after transportation(D10).Two hundred and forty25-day-old male SD rats were used and randomly divided into six groups: blank control group(I,60 rats,tested at time points D-3,D0,D0+,D3,D10),transport stress group(II,36 rats,tested at time points D0+,D3,D10),IAMC pre-transport addition group(III,48 rats,tested at time points D0,D0+,D3,D10),and Vitamin C pre-transport addition group(Ⅳ,48 rats,detection time points were the same as group III),IAMC post-transport addition group(V,24 rats,detection time points were D3,D10),Vitamin C post-transport addition group(VI,24 rats,detection time points were the same as group V).Rats in group I were not treated for transport,while rats in groups II,III,IV,V and VI were treated for transport stress for 3.5 h on the day of transport(D0+)(road transport,average speed 34 km/h,total distance 116 km,temperature 16°C,cloudy).Twelve rats were randomly selected and sampled from different test groups at each time point.The following tests were conducted:1.The effect of IAMC on the intestinal digestive function of transport-stressed ratsThe feeding and body weight of rats were recorded to determine the growth performance;fresh feces of rats were collected and the indices of crude protein,crude fat and crude fiber feed apparent digestibility were detected by Kjeldahl nitrogen determination method,Soxhlet extraction method and Van’s washing method respectively;the contents of rat ileum were collected and the indices of intestinal trypsin activity,lipase activity and amylase activity were detected by enzyme activity kit.The results are as follows:(1)The results of growth performance measurement showed that: in D-3～D0,the addition of IAMC before transportation could significantly increase the feed intake of rats,and the effect of vitamin C was not significant;in D0+,the transport weight loss of rats was obvious,and the use of vitamin C before transportation could significantly reduce the transport weight loss of rats;in each stage from D0+ to D10,the transport stress reduced the growth performance of rats to some extent,and the addition of vitamin C or Bal The addition of vitamin C or IAMC before transportation could improve the growth performance to some extent,and the continuous use of IAMC after transportation had a better effect on the improvement of the growth performance of the rats under transportation stress.(2)The results of apparent digestibility measurement showed that: in D0+,the apparent digestibility of rats’ diets in the transport stress group was significantly lower than that of the blank control group,and still did not return to normal level in D3 and D10;compared with the transport stress group,the apparent digestibility of rats’ diets in D3 and D10 could be significantly improved by the continuous use of IAMC after transport,and the apparent digestibility of rats in D10 could be improved by the continuous use of vitamin C after transport.Apparent digestibility,while the use of IAMC or vitamin C before transportation had no significant effect on it.(3)The results of digestive enzyme activity measurement showed that: in D0,the addition of IAMC or vitamin C before transportation had little effect on the intestinal digestive enzyme activity of rats within three days;in D0+,D3 and D10,the intestinal lipase activity of transport-stressed rats was significantly lower than that of the blank control group,and there was also a tendency for trypsin and amylase activities to decrease;the addition of IAMC before transportation improved the intestinal lipase activity of rats in D0+,D3 and D10 The intestinal lipase activity of D0+,D3 and D10 rats could be improved by adding IAMC before transportation;the continuous use of IAMC or vitamin C after transportation could improve the lipase activity of D3 and D10 transportation stress rats to normal level.2.Effects of IAMC on intestinal flora of transport-stressed ratsThe colon contents were collected aseptically from each group of rats after execution at different time points,and the effects of IAMC on intestinal flora of transport-stressed rats were investigated by high-throughput sequencing of 16 S r DNA amplicons.The results were as follows:(1)Alpha diversity analysis showed that at D0,pre-shipment vitamin C use for three days significantly reduced the abundance of rat intestinal flora,decreased the number of species and reduced community diversity,while pre-shipment addition of IAMC had no significant effect on the intestinal flora of normal rats;at D0+,there was no significant change in the Alpha diversity index of intestinal flora in transportstressed rats;at D3,transport stress resulted in The number of species of intestinal flora increased significantly,and the use of IAMC for three consecutive days after transportation significantly reduced the number of species of intestinal flora in transport-stressed rats;at D10,the Alpha diversity of intestinal flora in transportstressed rats returned to normal level.(2)Species difference T-test analysis showed that: at D0,pre-transport addition of vitamin C led to a decrease in the relative abundance of some metabolic function-related bacteria and some conditionally pathogenic bacteria;at D0+,transport stress reduced the relative abundance of rat intestinal probiotics to some extent and increased the relative abundance of some conditionally pathogenic bacteria,and pre-transport addition of IAMC increased the relative abundance of some probiotics;at D3,transport stress caused a decrease in the relative abundance of some nutrient metabolism-related bacteria and an increase in the relative abundance of some inflammation-related bacteria,pathogenic bacteria or conditionally pathogenic bacteria in the intestinal flora of rats,and the relative abundance of some conditionally pathogenic bacteria and inflammation-related bacteria in the intestinal flora of transport-stressed rats was significantly reduced by using IAMC for three days after transport;in D10,the addition of IAMC before transport increased the relative abundance of some The relative abundance of beneficial bacteria in the intestinal tract of transport-stressed rats was increased by pretransport addition of IAMC.(3)The results of Tax4 Fun analysis showed that: at D0,the addition of vitamin C before transportation led to an increase in the abundance of genetic information processing function and a decrease in the abundance of some metabolism-related functions in the intestinal flora of rats;at D0+,the abundance of genetic information processing function and the abundance of some metabolism-related functions in the intestinal flora of rats under transport stress decreased and the addition of IAMC before transportation promoted the structural optimization of the intestinal flora of rats after transportation.In D3,the environmental adaptation ability of rat intestinal flora was reduced,and the continued use of IAMC after transportation significantly enhanced the environmental adaptation ability of rat intestinal flora;while in D10,the relative abundance of intestinal flora in transport-stressed rats was not significantly different from that of normal rats.In summary,transport stress led to the decrease of growth performance,apparent digestibility of diet,intestinal digestive enzyme activity,increase of intestinal harmful bacteria abundance and decrease of probiotic bacteria abundance;the use of IAMC before or after transport could improve the growth performance and apparent digestibility of diet,increase the intestinal digestive enzyme activity and increase the relative abundance of probiotic bacteria and decrease the relative abundance of harmful bacteria;the effect of adding IAMC after transport The effect of post-transport addition of IAMC was somewhat better than that of pre-transport addition of IAMC. |
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