INVESTIGATING THE IMPACT OF DIETARY CATION-ANION DIFFERENCE VARIATION ON PHYSIOLOGICAL RESPONSES AND RUMEN FERMENTATION IN HEAT-STRESSED MALE ZANDI SHEEP

Recent attention has been drawn to the dietary cation-anion difference (DCAD), yet understanding remains limited regarding its influence on organic matter digestibility, blood parameters, and rumen fermentation in male Zandi sheep. This study aimed to elucidate the effects of varying DCAD levels on these parameters in male lambs experiencing heat stress. Forty male Zandi lambs, averaging 39 kg in body weight, were randomly assigned to five treatment groups, each with 8 replicates. Diets were formulated to contain different concentrations of DCAD (150, 300, 450, 600, and 750 mEq/kg dry matter). The experimental period spanned 100 days following a 21-day adaptation phase. Results indicated that the control group exhibited significantly higher values (P<0.05) for dry matter intake, crude protein digestibility, and dry matter digestibility. Additionally, ruminal pH was notably elevated in the control group (P<0.05). However, rumen fermentation parameters such as butyric acid, buffering capacity, acetic acid, propionic acid, the combined total of acetic acid and propionic acid, and the acetic acid to propionic acid ratio were unaffected by varying DCAD concentrations (P>0.05). Blood glucose parameters revealed significant differences (P<0.05), with the control group demonstrating the most significant impact on blood glucose levels. Conversely, no significant differences (P>0.05) were observed in other blood markers including potassium, magnesium, phosphate, cholesterol, and phosphate. Overall, our findings suggest that dietary manipulation of DCAD has no significant effect on rumen fermentation. However, it is noteworthy that lambs exposed to heat stress may sustain their apparent digestibility and output through increased DCAD intake.