Utilization of soft pistachio hulls in Japanese quail diets for enhanced egg quality and yolk pigmentation

Japanese quail (Coturnix coturnix japonica) offer rapid growth, early maturity and excellent feed conversion, but feed cost accounts for ∼70% of production expenses. This study evaluated soft pistachio hull (PH), an abundant agro-industrial by-product, as a low-cost dietary ingredient in laying quails.

Ninety-six female quails, seven weeks old age, were randomly distributed to four dietary groups (24 birds each; three replicates of eight birds). The treatment diets were based on a standard layer feed, with graded PH inclusion of 0%, 2%, 4%, and 6%, administered over a for five-week period. Parameters measured included live weight, feed intake, egg production rate, egg weight, feed conversion ratio, and a range of egg quality indicators, such as shape index, shell thickness, Haugh unit, albumen and yolk indices, and yolk color score, assessed at weeks 7 and 11.

Final live weight followed a cubic trend (P = 0.05), with the 2% and 6% PH groups (356.5 g and 350.6 g, respectively) exceeding the control (333.9 g), while 4% PH yielded intermediate values. Although differences in egg production were not statistically conclusive, the 4% PH group showed the highest output (76.4%). Feed intake increased by 7.3% in birds fed 4% PH group (P < 0.05), with feed conversion efficiency slightly reduced in noth 2% and 6% PH treatments. Egg shape index improved significantly at 4% PH (+3.3%, P < 0.01), whereas shell thickness, albumen index and Haugh unit remained unchanged (P > 0.05). Yolk color score exhibited strong linear, quadratic and cubic increases (P < 0.01), with the 6% PH group scoring 11.43 (+38.9% vs. 8.23 control).

Pistachio hulls can be incorporated into laying quail diets up to 6% without adverse effects on egg quality. The 4% inclusion level appears optimal for egg shape and pruductivity, while 6% maximizes yolk coloration. Nonetheless, the observed decline in feed efficiency at some levels suggests that careful ration balancing is essential. The use of PH represents a promising route for upcycling agro-residues into functional feed components with added economic and nutritional value.