SUPPLEMENTARY PROTEIN FOR LOW QUALITY BERMUDAGRASS DIETS AND MICROBIAL PROTEIN-SYNTHESIS

Ruminal and abomasal cannulated mature wethers were fed 800 g daily of low quality bermudagrass (49 days of age, containing 8.6% crude protein) and used in a 4 .times. 4 latin square experiment to study the effects of different protein supplements on the daily quantity protein and amino acids reaching the abomasum and on rumen microbial protein synthesis. Treatments were as follows: control (low quality Coastal bermudagrass, 69.0 g crude protein); control + 51 g crude protein (CP) equivalent from urea; control 51 g CP from sunflower meal (SFM); and control + 51 g CP from SFM treated with 1% formaldehyde (F-SFM). The addition of CP (irrespective of source) to the low quality forage diet resulted in a highly significant increase in quantities of total CP and non-ammonia CP reaching the abomasum daily. The substitution of SFM for urea also increased (P < .05) total and non-ammonia abomasal CP. Abomasal non-ammonia CP recovery was 1.44 times as high (P < .01) in wethers fed the F-SFM diet as in those fed the control diet. Addition of CP to the low quality diet failed to increase the daily quantities of lysine, histidine, arginine, cystine, methionine or phenylalanine reaching the abomasum; total quantity of essential amino acids reaching the abomasum was increased by the addition of CP to the control diet. The addition of sunflower meal to the control diet significantly increased the daily quantity of all essential amino acids recovered from the abomasal digesta. All individual nonessential amino acids, except proline by the F-SFM treatment and tyrosine by the addition of CP and total nonessential amino acids were increased significantly in the abomasal digesta by the addition of protein, SFM and F-SFM to the control diet. Microbial protein synthesis was increased (P < .01) by the addition of sunflower protein, but urea had no effect. The F-SFM treatment also increased (P < .01) the recovery of dietary protein from the abomasal digesta.