The Research Of Proteinlevel In Calf Starter

The influence of different protein level in calf starter on ADG, ADI, wither height, digestibility, rumen and duodenum development and biochemical indicators of weaned calves from 61 to 120days old were studied in this paper.The experiment was randomized block designed and divided into 3 groups with 5 calves each. There was no significant differences of BW, wither height, parity and parents among the calves in each group (P>0.05).The protein level of the three groups were 21.5%,19.5%,17.5%. Alfalfa hey was limited supplied and corn silage was sine die supplied in the whole experiment. Water was freely drunk and every calf was reared in a single pen. The experimental stage lasted for 60 days and the calves were feed at 09:00,16:00 everyday.Calves were weighted as an initial weight after pre-experiment, and then weighted every 20days. At the beginning and the ending of the experiment, the body measurement (wither height, body slanting length and average canon bone) were measured. Two calves in one conduct were randomly selected and blooded at jugular. Each blood sample was 10ml.After 5 days pre-feeding, the fecal samples which were prepared to test the digestibility were collected everyday at 8:00,13:00,18:00 and each sample was no less than 100g. The calves were sacrificed by exsanguination to make rumen wall and duodenum sample for histological section and rumen physiological index test. The data was analyzed by SPSS software.The result shows that there were significant differences between group 2 and 3 in ADG and the average daily intake of starters , group 1,2 and 3 in heart girth(P<0.05). However, there were no significant differences among these treatments in wither height, body slanting length and average canon bone increase.The DM, CP, EE, energy and the apparent digestibility of NDF of Group 2 were higher than that of group 1 and 3. There was a significant different between group 1 and 3 in DM and AD of NDF(P<0.05)and between group 1,2 and group 3 in ADF(P<0.05).Slaughtering performances and anatomy structures showed that every complex stomach anatomy indexes in group 1 and 2 were higher than that in group 3 at the age of 120 days. But statistical analysis showed that the results were not significant different except rumen average volume between group 2 and 3.But the average length of rumen papillary and the average volume of reticulum had significant difference between group 2 and 3.In the analysis of biochemical indicators in blood, all the analytical value of three groups was within normal limits and they except the urea nitrogen concentration exceeded the normal level. The TGL density was a little higher in the three groups.Analysis showed that the starter diet of 19.29% protein level had insignificant effects in calves to promote the daily average of feed intake and body weight gain, the increasing of the important body indices, and the development of complex stomach. It also had the highest digestibility in feedstuffs for calves compared with the starter diet protein levels of 21.16% and17.22%.According to detection of blood biochemical indexes, calves have better enduring ability with the protein levels from 17.22%-21.16%.Their blood biochemical indexes were in a normal range, but we found that the higher protein dietary had significant difference in the concentration of total serum protein,urea nitrogen and triglyceride.