In this research, our main objective was to examine the impact of various additives, specifically Synbiotic (SYN), Copper sulfate (CuSO₄), Yucca schidigera (YS), and Bentonite (BN), on the physiological parameters and productivity of Inshas laying hens. A total of 150 (54 week-old) hens from the Inshas local strain, were individually weighed and divided into five experimental groups with three replicates each (10 hens per group). The control group was given a basic diet (T1), while the other four groups were given the basic diet (T1) supplemented with SYN (at 0.5g/kg), CuSO₄ (at 50 ppm), YS (at 0.5g/kg), or BN (at 20g/kg). After implementing these dietary treatments, hens which received SYN showed the highest number of eggs (EN), egg mass (EM), and egg production rate (EPR). Overall, the productive traits (EN, EM and EPR) significantly increased, while the feed conversion ratio significantly improved (p<0.05) for hens which received the supplemented diets (T2:T5) compared to those who only had the T1 diet. Additionally, there was a significant increase in egg weight (EW) for those which had either CuSO₄ or BN added to their diet. The inclusion of YS or BN in the diet also resulted in a significant increase in yolk weight (%), while SYN or CuSO₄ led to an increase in albumen weight (%). Despite variations in dietary treatments, there were no notable discrepancies in the percentage and thickness of eggshells. Conversely, including SYN led to a decrease in yolk weight (%) as opposed to the control group. Generally, there were no significant differences in egg quality among groups with different additives, except for the significantly higher yolk and shell weight percentages in the control group. Hens on a diet supplemented with CuSO₄ had increased levels of total plasma protein (TP), while those on SYN had increased levels of both albumin (Alb) and total antioxidant capacity (TAC). However, the highest levels of plasma globulin (GLO) were observed in hens on a diet with BN, when compared to other treatments and the control. The addition of CuSO₄ to the diet redounded in a significantly higher H/L ratio compared to other treatments and the control. We recommend the use of additives in the feed such as synbiotics for positive effects on egg production, to improve egg quality; and copper sulphate to improve some chemical and immunological characteristics in blood parameters.
Key words: Feed additives; productive performance; egg quality; blood parameters