| In order to explore the development of digestive system and expression rule of H-FABP gene in muscle for Tibetan sheep, Oula Tibet sheep that distributed over Maqu County of Gansu Province where located in east Qinghai-Tibet plateau were used as the study objects. 60 male lambs were slaughtered at 0, 2, 7, 14, 21, 28, 42, 56, 72, 84, 98, and 112 daily age respectively. In the study, main technology included dissection technique, active analysis of enzyme, growth curve model, real time PCR and so forth. The important research contents were developmental changes of digestive system, microbe enzyme activity in rumen, digestive enzyme activity in abomasum and small intestine as well as pancreas, growth curve model for digestive organs, expression of H-FABP gene and its correlation with intramuscular fat (IMF) in muscle. The main results are as follows.1 Developmental changes of digestive enzyme activity in rumen and digestive organs in Oula Tibetan sheepThe determined index were body weight, body measurements, liver weight, pancreas weight, weight of stomach and its content, net weight and relative weight of small intestine and large intestine and cecum, stomach capacity and intestine length, pH in stomachs and digestive enzyme activity in rumen. The results indicated: first, with age increasing, weight, capacity and length of all parts of digestive system were increasing obviously, especially the weight of rumen and small intestine was quicker than that of other parts. Second, due to grazing pasture activate development of rumen, at the age of 70 days, pH in rumen of Oula sheep reached the level of adult sheep and kept relative stability, in addition, the pH in abomasum was lower and showed strong acidity. Third, with age increasing, Oula Tibetan sheep digestive enzyme activity in rumen increased, in which, activity ofα-amylase and xylanase increased obviously, activity of cellulose and pectinase increased slowly, while, activity of protease decreased slowly, activity of cellulose kept lower level. At the age of 112 days, digestive system and function of Oula sheep reached the level of adult sheep. Fourth, in productive practice of Oula sheep, lambs can be weaned at the age of 70 days, 56 daily age is the earliest weaning time which can be accepted.2 Fitting analysis of growth curve for digestive organs in Oula Tibetan sheepFitting growth curve of different digestive organs in Oula sheep was analyzed in CurveExpert 1.3 and SPSS 11.5 software. The results showed: in early age, body weight, body measurements and digestive organs of Oula sheep accord with the natural law of biological growth. Richards model was the best model fitting early growth of body weight and heart girth of Oula sheep, R~2 was 0.9900858 and 0.9956355 respectively. Exponential Association model was the best model fitting early growth of body height and body length of Oula sheep, R~2 was 0.9958635 and 0.9989817 respectively. Gompertz Relation model was the best model fitting growth of rumen, recticulum and omasum weight of Oula sheep, R~2 was 0.9969633, 0.9990474 and 0.9991166 respectively. 4th Degree Polynomial Fit model was the best model fitting growth of abomasum, duodenum, ileum, cecum, liver and pancreas weight of Oula sheep, R~2 was 0.9982634, 0.9995719, 0.9993717, 0.9993425, 0.9982556 and 0.9987633 respectively. Logistic model was the best model fitting growth of jejunum and restum weight of Oula sheep, R~2 was 0.9993071 and 0.9995853 respectively. 4th Degree Polynomial Fit model was the best model fitting growth of stomachs cubage of Oula sheep, as to R~2 of rumen, recticulum, omasum and abomasum, R~2 was 0.9998086, 0.9960602, 0.9979316 and 0.9843221 respectively. 4th Degree Polynomial Fit model was the best model fitting growth of intestine length of Oula sheep, as to R~2 of duodenum, jejunum, ileum, cecum and rectal, R~2 was 0.9989660, 0.9986684, 0.9962898, 0.9986193, 0.9972662 and 0.9982142 respectively.3 Change of main digestive enzyme and pH in digestive system of Oula sheepMucosa and content of abomasum and small intestine as well as pancreas were sampled to determine their pH and activity of digestive enzymes. The results indicated: first, with age increasing, pH of content and mucosa in abomasum of lambs decreased, appearing strong acidity. At birth, pH of content and mucosa in abomasum were significantly higher than that of other daily age (P<0.05)After d42,pH of content and mucosa in abomasum of lambs almost not changed (P>0.05). Second, chymosin activity in abomasum of lambs was higher at birth.With age increasing, chymosin activity decreased quickly. Before d42 chymosin activity in abomasum of lambs changed to large extent,but after d42 chymosin activity in abomasum of lambs almost not changed. Protease activity in abomasums contents was lower.Protease activity in pyloric gland region of abomasum was lower than that of fundic gland region and cardic gland region(P<0.05) protease activity in fundic gland region and cardic gland region was insignificantly(P>0.05). Afte d42 protease activity of fundic gland region in abomasums mucosa kept stability. Pregastric esterase activity in abomasums contents of lambs was higher at birth. Third, with age increasing, pH of pancreas and small intestine almost not changed. pH of pancreas was above 7, appearing alkalescence. pH of ileum was higher than that of jejunum (P<0. 05), pH of jejunum was higher than that of duodenum (P<0. 05), pH of duodenum was lowest. In addition, pH of duodenum appeared feeble acidity, pH of jejunum and ileum appeared alkalescence. Fourth, trypsinase and chymotrypsin activity in small intestine of lambs were higher at birth.Trypsinase and chymotrypsin activity in jejunum were highest, next in ileum, the lowest in duodenum. With age increasing, trypsinase and chymotrypsin activity in small intestine of lambs increased. After d70, trypsinase and chymotrypsin activity in small intestine of lambs kept relatively stable. Fifth,α-amylase activity in different parts of small intestine was different,α-amylase activity in jejunum was significantly higher than that in duodenum and ileum(P<0.05). With daily age of Oula sheep growing,α-amylase activity in small intestine increased continually, after 84 daily age,α-amylase activity in small intestine kept relative stabilization.Lactase activity in small intestine of lambs were higher at birth.Lactase activity in different parts of small intestine was different, lactase activity in jejunum content and mucous was highest, next was duodenum, and ileum was the lowest. Lactase activity in small intestine mucosa was significantly higher that in content. With age increasing, lactase activity in small intestine of lambs decreased. After d70 ,lactase activity in small intestine of lambs kept relatively stable. Sixth, lipase activity in different parts of content and mucosa in small intestine was different for different daily lambs, lipase activity in jejunum was highest, next was ileum, the lowest was duodenum. Lipase activity in small intestine content was significantly higher than that in mucosa(P<0.05). With age increasing, lipase activity in small intestine increased gradually.After d84 lipase activity in small intestine kept relatively stable. Seventh, with age increasing, digestive enzyme in pancreas almost not changed.4 Developmental change H-FABP gene expression and its effect on IMF in lamb muscleLongissimus thoracis, biceps femoris muscle and heart of male lambs at the age of 2, 21, 56, 84 and 112 days were sampled respectively. IMF and H-FABP mRNA expression in muscle were analyzed. The results indicated: first, with age increasing, IMF in muscle was increasing continually, in addition, IMF in different tissue was different; second, with age increaing, H-FABP mRNA expression in muscle changed, H-FABP mRNA expression in different tissue was different. From 2 to 21 daily age, H-FABP mRNA expression in muscle decreased, after d21, H-FABP mRNA expression in muscle was increasing continually, the difference at different daily age was significant. From 21 to 112 daily age, H-FABP mRNA expression in muscle and IMF appeared the positive correlation, so, H-FABP gene affected IMF in early growth and development of lambs, H-FABP gene can be used as the candidate gene controlling IMF in Oula Tibetan sheep. |
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