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

## TL;DR

This study shows that adding soft pistachio hulls to Japanese quail diets improves yolk color and egg shape without harming egg quality.

## Contribution

The study introduces soft pistachio hulls as a viable, low-cost feed ingredient for enhancing quail egg quality and yolk pigmentation.

## Key findings

- A 4% inclusion of pistachio hulls improved egg shape index and productivity in quails.
- A 6% inclusion maximized yolk coloration without adverse effects on egg quality.
- Feed efficiency slightly declined at 2% and 6% inclusion levels.

## Abstract

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.