Determinating the relationship between starch level and acidosis in high starch containing diets in lambs

Abstract

The aim of this study was to determine the effects of high starch levels in the diet on the formation of subacute acidosis in lambs and to determine the ideal starch level in lamb fattening diet. Three different diets with starch content of 25% (1st Ration-R1), 30% (2nd Ration-R2) and 32% (3rd Ration-R3) were prepared to induce subacute rumen acidosis to achive this purpose. These diets were fed to 6 Akkaraman lambs, aged 11-12 months, with a body weight of 30-35 kg, in a repelicated 3x3 Latin Square design to determine daily nutrient consumptions and digetibilities of nutrients. Rumen fermentation parameters (pH, organic acid and ammonia nitrogen) were determined in the rumen fluid sampled at 0, 2, 4, 6, 8 hours post-feeding in each period. Blood samples were also taken at 0- and 6-hours post-feeding in order to determine blood gases and blood biochemistry parameters. Blood glucose, total protein, triglyceride, urea, creatinine and albumin, pH, pCO₂, HCO₃ and base clearance were measured in these blood samples. It was observed that the daily nutrient consumptions of animals decreased in parallel with the increases in starch in the diets (P<0.05). Similarly, in parallel with the increase in the starch level of the diet, there was a general tendency to decrease in digestion of nutrients other than starch (P=0.08). There was no statistical difference in general between rumen pH, total organic acid, organic acid ratios, only rumen ammonia levels were found to differ between the groups before and immediately after feeding (2nd hour) (P<0.05). While blood pH values ​​and HCO₃ values ​​decreased after feeding, no significant change was observed in other parameters. Among the blood biochemistry parameters, only creatinine decreased statistically (P<0.01) in the R1 group after feeding, and no difference was observed between other parameters. There was no signiicant difference among the groups in any of the blood parameters. It can be concluded that increasing the starch level above 25% in the diets of lambs adversely affects the nutrient consumption and nutrient digestion of the animals in general, and also reduces the blood pH and HCO₃ levels, thus creating a risk of subacute acidosis.