Studies On Protein And Energy Requirements Of Loaches

Loaches (Mwasgurnus anguillicaudatus) were used as experimental animals to determine the digestive tract index and the main digestive tract enzyme activities, the in vitro digestibility of 11 feed ingredients, dietary protein and energy levels on loach growth index, feed conversion efficiency, muscle composition and the main digestive enzyme activities in three respectively independent Experiments.1. Studies on digestive tract index and the main digestive enzyme activities of loaches. 200 loaches aged 2 were used as test animals; intestinal tract index and intestinal tract and the major digestive enzyme activities of intestinal tract and hepatopancreas were determined according to conventional methods. The results showed that:(1)Loach was no stomach fish, so their digestion and absorption were performed in the intestine;(2)The ratio of the length of the intestines to the length of the body was 0.465±0.065; the ratio of the weight of the intestines to the weight of the body was 0.027±0.005; the ratio of the weight of the hepatopancreas to the weight of the body 0.016±0.007; the ratio of the weight of the offalto the weight of the body was 0.102±0.024; Compared with other fish, oncorhynchus mykwass,Cyprinus carpio,pelteobarus fulvidraco,pseudosciaena crocea and erythroculter ilwashaeformwas, loach intestinal had the shortest relative length;(3)Compared with cyprinus carpio, hypophthalmichthys molitrix, mylopharyngodon piceus and other fish, the notable features of loach was that hepatopancreas digestive enzyme activities in the main protease and amylase activity were the highest, while the lipase activity was the lowest.2. In vitro digestibility coefficient of eleven common feed ingredients for loaches. 60 loaches aged 2 with weight 11.65±1.04g, lengh 11.29±0.47cm were used as test animals; digestive tract crude enzyme was extracted by conventional methods, and 11 common feed ingredients for dry matter, crude protein and crude fat in vitro digestibility were determined for loaches. The results showed that: (1)In vitro digestibility of 11 kinds of common feed ingredients for dry matter, crude protein and crude fat for loach varied significantly between species(P<0.05), and the difference in dry matter, crude protein and crude fat between the three components was not in complete agreement. Based on in vitro digestibility comprehensive evaluation results of dry matter, crude protein, crude fat, loach digest of the best for animal protein in the plasma protein powder materials, followed by fish meal, while soybean meal in feed digestion plant the best, followed by cottonseed meal.(2)Loach has a significantly higher digestibility of crude protein than crude fa(tP<0.05), higher digestibility of fat in animal feed than in plant feed(P<0.05), better digestibiltity of protein feed than energy feed .3. The effect of dietary nutrition level on loach growth index, feed conversion efficiency, muscle composition and the main digestive enzyme activities900 loaches with close birthday and close weight of 5.04g were used as the experimental animals. With 4×3 factorial design, researched the dietary protein level (25%, 30%, 35%, 40%) and energy level (13.5MJ/kg, 14.0MJ/kg, 14.5MJ/kg) on loach growth index, feed conversion efficiency, muscle composition and main digestive enzyme activities. The results showed that:(1)The level of dietary protein has significantly effect on specific growth rate and feed conversion ratio (P<0.05); feed energy level has no significant effects on the three(P>0.05); however, the level of feed energy and protein ratio has significantly effect on the specific growth rate ,feed conversion ratio and protein efficiency ratio(P<0.05).(2) With the increase in dietary protein level, specific growth rate, feed conversion efficiency and protein efficiency ratio firstly increased and then decreased; dietary protein levels of 35% showed the best performance; With the increase in dietary E/P level, Specific growth rate and feed conversion efficiency decreased, protein efficiency ratio first increased and then decreased; in this study, E/P feed the best performance was the 38.57 kJ/g.(3) Dietary protein and energy levels has no significant effects on the loach muscle water content, crude protein and crude ash content (P>0.05),except fat content (P<0.05).(4) Protein level has significantly effect on the intestinal protease activity(P<0.01); hepatopancreas amylase activity has significantly effected(P<0.05), feed energy level has significantly effect on the intestinal lipase, hepatopancreas lipase and hepatopancreas amylase activity (P<0.05), other enzyme activity have no significant effect (P>0.05).(5) 11 regression equation that reflect loach growth indicators, feed conversion efficiency and the main digestive enzyme activities were established, respectively; dietary protein levels and energy level and the E/P level of the relationship, and the indexes of each of the loach as evaluation criteria dwascussion the suitable for feed protein level, energy level, and E/P level, dietary protein level of which 36.47% ~ 36.31%, E/P level of 32.21 ~ 33.07 kJ/g, the loach maximum specific growth rate, the lowest feed conversion ratio; 30.3% protein level, E/P level 50.92 kJ/g, the maximum efficiency of protein; when the protein level of 33.69% ~ 34.80% the loach intestine and hepatopancreas has the highest protease activity; When the energy level 14.4MJ/kg, loach has the highest intestinal lipase activity, when the energy level 13.5MJ / kg, loach has the highest hepatic pancreatic amylase activity.(6) Comprehensive analyswas found that best feed protein level and energy level for loach was at 36.31% ~ 36.47% and 13.5 MJ/kg - 14.4 MJ/kg respectively.