Effects of synchronizing starch and protein degradation in rumen on fermentation, nutrient utilization and total tract digestibility in sheep

Abstract

The objective of this experiment was to investigate the effects of synchronizing the dietary starch and crude protein (CP) degradation in the rumen on nutrient utilization, fermentation, and total tract digestibility in sheep. The four diets were formulated with different rates of starch and CP release in the rumen but with similar metabolic energy, starch, and CP. The diets were slowly degradable starch, slowly degradable protein; slowly degradable starch, rapidly degradable protein; rapidly degradable starch, rapidly degradable protein; and rapidly degradable starch, slowly degradable protein. The diets were fed to four cannulated sheep ad libi- tumin two equal portions, using a 4x4 Latin square design. Dry matter intake (DM) was not influenced by either the rate of starch or protein degradation. There was no significant effect of dietary treatment on the digestibility of DM, organic matter, starch, CP, neutral detergent fiber or acid detergent fiber in the rumen and total tract. Ruminal pH was greater for sheep fed slowly degrad- able starch diets than rapidly degradable starch (P< 0.05). Ruminal total volatile fatty acid concentrations were not affected by treatments but the molar proportions of propionic acid were greater for sheep fed rapid- ly degradable starch diets than slowly degradable starch diets (P< 0.05). The ratios of acetic acid (A) to pro- pionic acid (P) were higher for sheep fed slowly degradable starch diets than rapidly degradable starch diets (P< 0.05). Ruminal ammonia-N concentrations were not affected from the degradability characteristics of protein. Rumen pH and A:P were higher in diets containing slowly degradable starch than in diets rapidly degradable starch. Propionic acid was higher in diets containing rapidly degradable starch than in diets con- taining slowly degradable starch. Rumen fermentation and utilization of nutrients in the rumen affected starch degradability more than protein degradability. Synchronizing starch and protein degradation in rumen had no effect on the intake, digestibility of nutrients in sheep.

Keywords

• Starch, Protein, Degradability, Synchrony, Sheep