Prediction Of Metabolizable Protein On Meat Sheep

The aim of this study is to predict metabolizable protein on meet sheep and provide the theoretical basis for feeding standard of meat sheep.Six crossbred (Suffolk(♂×Altay♂) rams with permanent cannulas in the rumen and the proximal duodenum were divided into6groups (4trial periods) according to6×4uncompleted Latin square experiment design, and fed with six different forage to concentrate ratio of85:15,70:30,55:45,40:60,25:75and10:90, respectively. Experiment lasted for104days including four periods that lasted for26days, and the first10days of each experiment were preparatory feeding, sampling during the11day to the26day of each period. The flow of chyme to the duodenum was determined using Cr(Cr-fiber solid phase marker) and Co(Co-EDTA, liquid phase marker) as dual-phase markers. Metabolizable protein, the ruminal pH and the digestible nutrients were determined. Prediction model was established for metabolizable protein using the predicting factors such as nutrients content in diets and digestible nutrients. The results showed that:1. With the decrease of forage to concentrate ratio of total mixed ration, the ruminal pH value increased (p<0.05). The ruminal pH value of each treatment group at9:00,11:00,15:00,19:00and21:00differed significantly (p<0.05). The ruminal pH value of each treatment group first decreased, then increased with the passage of time after feeding; the groups that were fed with forage to concentrate ratio of55:45,40:60and25:75differed extremely (p<0.01), the group that was fed with forage to concentrate ratio of10:90differed significantly (p<0.05).2. With the decrease of forage to concentrate ratio of total mixed ration, the digestibility of dry matter, organic matter, crude protein and ether extract significantly decreased (p<0.05). The digestibility of crude protein of the diet with forage to concentrate ratio of10:90was significantly lower than the other diets (p<0.05), the digestibility of crude protein of the diet with forage to concentrate ratio of25:75was significantly lower than the diets with forage to concentrate ratio of85:15,70:30,55:45and40:60(p<0.05); the digestibility of ether extract of the diet with forage to concentrate ratio of10:90was significantly lower than the diets with forage to concentrate ratio of85:15and70:30(p<0.05). 3. With the decrease of forage to concentrate ratio of total mixed ration, the dilution rate of ruminal fluid phase increased (p<0.05), the treatment group that was fed with forage to concentrate ratio of85:15was significantly lower than the treatment group that was fed with forage to concentrate ratio of10:90(p<0.05).4. With the decrease of forage to concentrate ratio of total mixed ration,effective degradation rate of protein in the rumen decreased (p<0.05), the treatment groups that were fed with forage to concentrate ratio of40:60,25:75and10:90were significantly lower than the treatment groups that were fed with forage to concentrate ratio of85:15and70:30(p<0.05).5. Metabolizable protein (MP) was significantly related to the nutrition and the digestible nutrition of feeds. The following are the prediction equations for MP (g/kg DM):MP=1.23OM-1054.67(R2=0.8444, n=6, p=0.0096),MP=0.96CP-87.89(R2=0.9383, n=6, p=0.0015),MP=-0.17NDF+134.51(R2=0.8934, n=6, p=0.0044),MP=0.75DP-25.82(R2=0.9105, n=6, p=0.0031),MP=0.41OM+0.69CP-415.55(R2=0.9598, n=6, p=0.0080),MP=-3.79OM-0.68NDF+3784.23(R2=0.9570, n=6, p=0.0089),MP=0.62CP-0.07NDF-6.45(R2=0.9629, n=6, p=0.0072),MP=0.69CP-0.06ADF-31.90(R2=0.9807, n=6, p=0.0027).