Study On The Digestion And Caecotrophy Composition Of Muskrats By Three Diets With Different Fiber Contents

8 of adult male muskrats,with body weight of 1368±121 g,in single cage,freely access to diet and drinking.Feed pellets with fiber content of 17.3%(Diet 1),21.6%(Diet 2),and 25.7%(Diet 3)in the three different experimental periods.The voluntary feed intake(VFI),apparent digestibility(AD)of diets,the amounts(by the methods of whole collection or PEG labling),compositions of nutrients and microbe of feces and caecotrophy(by classical microscopic and PCR countings),were measured,to study th effect of contents of Fiber in diets on VFI,AD and caecotrophic composition.Each experiments period is 23 d,of which the pre-experiments period is 15 d and the feces collection period is 8 d.The results showed that the VFI were 51.4 g/d,51.8 g/d,52.0 g/d;the AD was 56.7%,54.8%,54.4%;It shows that the dietary Fiber content has no significant effect on the VFI and AD of muskrats(P>0.05).However,the AD of CP,phosphorus and energy in experiments 2 was reduced by 8.1%(P<0.01),13.3%(P<0.01)and 8.7%(P<0.01).The AD of cellulose,hemicellulose and calcium increased by31.1%(P<0.01),7.2%(P<0.01);Experiments 3 decreased by 12.9%(P<0.01),20.0%(P<0.01)and11.1%(P<0.01),and increased by 60.6%(P<0.01),9.5%(P<0.01)and 8.3%(P<0.01);It shows that the dietary fiber content reduces the AD of crude protein,but increases the AD of fiber.In the three experiments,the numbers of caecotrophy protozoa of muskrat were 68.8×10~5/g,56.7×10~5/g(P<0.01)and 44.50×10~5/g(P<0.01)(fresh feces),more than feces 107.0%,129.0%and 186.3%;The total number of bacteria were 40.5×10~9/g,69.6×10~9/g(P<0.01)and 87.2×10~9/g(P<0.01)(fresh feces),more than feces 207.0%,212.0%and 115.3%;The R.albus were 10.3×10~7copies/g,14.8×10~7copies/g(P<0.01)and 31.2×10~7copies/g(P<0.01)(fresh feces),more than feces 844.0%,979.5%and 873.7%;The R.flavefaciens were 15.3×10~6copies/g,18.0×10~6copies/g(P<0.01)and 45.8×10~6copies/g(P<0.01)(fresh feces);more than feces 192.1%(P<0.01),152.1%(P<0.01)and 470.7%(P<0.01);The F.succinogenes were 45.8×10~6copies/g,63.3×10~6copies/g(P<0.01)and 73.6×10~6copies/g(P<0.01)(fresh feces),more than feces 1300.6%(P<0.01),1151.7%(P<0.01)and1069.3%(P<0.01);The changes of feces and caecotrophy of B.fibrisolvens,S.ruminantium,Methannogens and S.bovis with dietary fiber content are similar to those of the above bacteria;The fungi were 3.3×10~7copies/g,5.9×10~7copies/g(P<0.01)and 7.4×10~7copies/g(P<0.01)(fresh feces),more than feces 183.7%(P<0.01),295.2%(P<0.01)and 142.4%(P<0.01);It shows that the microbial content of caecotrophy is high,and with the increase of dietary Fiber content,the number of bacteria in feces increases and the number of protozoa decreases.The total amino acids of caecotrophy were 52.5mg/g,47.2 mg/g(P<0.01)and 41.3 mg/g(P<0.01)(fresh feces),more than feces 69.4%(P<0.01),78.8%(P<0.01)and 95.7%(P<0.01);Lysine was 2.9 mg/g,2.6mg/g(P<0.01)and 2.4 mg/g(P<0.01)(fresh feces),more than feces 81.3%(P<0.01),85.7%(P<0.01)and 81.8%(P<0.01);Methionine was3.6 mg/g,2.7 mg/g(P<0.01)and 2.2mg/g(P<0.01)(fresh feces),more than feces 88.0%(P<0.01),60.7%(P<0.01)and 52.4%(P<0.01);It shows that the content of amino acid in caecotrophy is high,and the increase of dietary Fiber content will reduce the content of amino acid in caecotrophy.The DM yield of muskrat caecotrophy in the three experiments were 8.1 g/d,8.3 g/d and 8.4 g/d.The average daily OM,CP,energy,calcium,and phosphorus accounted for 19.4%、24.0%、21.2%、10.3%and 26.3%of the muskrat’s DM.It is concluded from this experiment that the dietary fiber content of muskrats has no significant effect on VFI,but reduces the digestion of CP,phosphorus and energy,and increases the digestion of fiber;adult muskrats produce about 8.2 g of caecotrophy per day,and It is not affected by dietary fiber content;the content of microorganisms and amino acids in caecotrophy is more than that of feces,but with the increase of dietary fiber content,the content of protozoa and amino acid in caecotrophy decreases,and the content of bacteria increases;caecotrophy can be supplied muskrats account for about 20%of the total digestible OM and other nutrients,and is an important source of muskrat nutrition.