Study On Nutritional Type Of Forages And Crop Straws In Tibet

The nutritional value of forages mainly lies on the nutritional types and contents of feeding parts. Research on the nutritional type of forages and crop straws could reveal their nutritional characters and promote the productivity of livestock farming in Tibet.57 cultivated forages,11 natural forages and some common crop straws were used as experimental materials in this research. Nutritional components, the constitutive characteristics of amino acid and caloric value, together with nutritional components like CP, EE and CF had been studied.The results showed that:1,There were reasonable constitutive ratio of amino acid and high nutritional value in 57 cultivated forages.The TAA(Total amino acid) content ranged from 6.11% to 23.71% and the average content of EAA (Essential amino acid) was 6.42%, with the highest contents in Leguminosae. The sulfur amino acid content ranged from 0.44% to 1.63%, which varied greatly among species. There was also a high ratio of limited amino acid contents in cultivated forages. Meanwhile,82% cultivated forages species showed EAA/NEAA>60% and EAA/TAA>40%, simultaneously.2,The average caloric value of cultivated forages and natural forages was 18.81kJ/g and 17.23 kJ/g, respectively.Ash free caloric values (AFCV) of all the forages were relatively higher than that of the terrestrial plants in the world, whose average caloric value was 17.79kJ/g, and 95.65% of the forages belonged to medium or high caloric value forages. Meanwhile, crop straws had lower caloric values, whose AFCV was 17.75 kJ/g on average.GCV(Gross caloric value) of the crop straws showed negative correlation with ash contents.3,In 57 cultivated forages, the nutritional type of Gramineae and Leguminosae mainly belongs to the nitrogen and nitrogen-carbon type with high CP content and low CF, which has the higher nutritional value relatively. The several common crop straws, mainly belonging to the carbon or carbon-nitrogen type, had a lower nutritional value. There is only 4% of CP content in the crop straws of wild oat and wheat, which are primarily used as coarse fodder and should be fed together with concentrated feed to supply the livestock with enough nutrition.