*3.4. Nitrogen Profile*

Changes in protein, albumin, and urea levels are needed to diagnose disorders of nitrogen metabolism [48]. The highest but statistically non-significant content of total proteins (*p* = 0.380), globulin (*p* = 0.548), and urea (*p* = 0.564) in GP1 was found (Table 5). However, in the control, the highest albumin content was observed but statistically nonsignificant (*p* = 0.154). After the GP addition, a narrower ratio between albumin and globulin (C 0.83/1; GP1 0.43/1; GP2 0.63/1) was observed. Alba et al. [27] reported statistically significant lower TP, GLB, and urea after grape residue flour (2% from concentrate)

addition in lactating dairy sheep in comparison with the present study. Alba et al. [27] also determined similar results after GP feeding on albumin (statistically non-significant). Bahrami and Chekani-Azar [42] found no significant effect of GP on the content of total proteins. The concentration of total proteins, albumin, globulin, and urea were in the reference range [21,56]. In contrast to our results, Panev et al. [57], Carlos et al. [58], and Jelinek et al. [59] reported lower average total proteins in wethers, in Morada Nova sheep, as well as generally in sheep.
