Gancho Ganchev1, Milena Mihaylova2 and Dimo Penkov3
1 Department of Fundamental Sciences in Animal husbandry, Faculty of Agriculture, Trakia University – 6000 Stara Zagora, Bulgaria
2 Agricultural Academy, Agricultural Institute – 6000 Stara Zagora, Bulgaria
3 Agricultural University – Plovdiv, 4000 Plovdiv, Bulgaria
Ganchev, G., Mihaylova, M. & Penkov, D. (2026). Effect of dietary protein source on net utilization of energy and protein in the carcass of fattening steers. Bulg. J. Agric. Sci., 32(2), 435–439
A comparative study of the net energy and protein utilization of 2 groups of fattening calves from 200 to 407 days of age, which received nitrogen from different sources – urea and sunflower meal, was conducted. Newly introduced indices „Clarc of energy distribution (CED)“ and „Clarc of protein transformation (CPT)“ expressing the transformation along the chain „net energy/intestinally digestible protein in feed – gross energy/crude protein in boneless meat“, were used.
The authors found a lower utilization of net energy for growth (CED = 5.78 against 7.22%), but a higher utilization of protein (CPT = 17.10 against 15.73%) in calves receiving forage protein via urea compared to those receiving it via sunflower meal.