A December 2026 paper in Poultry Science (Volume 105, Issue 12) tests spinach and labada leaf powders, with and without non-starch polysaccharide-degrading enzymes, in late-phase laying hens. The study reports performance, egg quality, and yolk pigmentation outcomes. Lead authors Yonis Saab Najim and Saif Ali Khashan worked with co-authors Rifat Ullah Khan and Yusuf Konca.

What the trial compares

The title frames a 2 × 2 factorial arrangement: two leaf-powder sources (spinach versus labada, a Rumex species also called sorrel or patience dock) crossed with enzyme supplementation status. That structure yields four treatment combinations. The journal lists four authors; affiliations are not shown in the source.

Why "late phase" matters

Late-phase laying hens sit past peak production, generally beyond 45 to 50 weeks of age. Egg output declines. Feed conversion worsens. Shell quality drops. Nutritionists target this stage with cost-controlled additives that hold performance without pharmacological inputs. Leaf meals fit that brief: locally available in many regions, cheap, and pigment-rich.

What NSP-degrading enzymes do

Non-starch polysaccharides are cell-wall components — cellulose, hemicellulose, beta-glucans, arabinoxylans, pectins — that poultry cannot digest. They raise digesta viscosity, slow absorption, and trap nutrients. Adding enzymes such as xylanase, beta-glucanase, cellulase, or multi-enzyme cocktails breaks the cell walls, releases trapped starch and protein, and reduces gut viscosity. The mechanism explains why researchers pair enzymes with fibrous plant meals: the enzyme offsets the fiber penalty the leaf meal would otherwise impose.

Why yolk pigmentation is the headline outcome

Egg yolk color sells. Pigment intensity depends on dietary xanthophylls — carotenoids the hen absorbs from green plants, yellow corn, and algae. Spinach delivers lutein and beta-carotene. Rumex species carry similar carotenoids alongside oxalates that bind calcium. If labada lifts yolk color without dragging down shell quality, the additive has a clear commercial case. If the NSP enzymes rescue nutrient digestibility enough to raise pigment absorption, the combination looks attractive.

What the design can and cannot tell

The factorial design isolates each factor's main effect and tests for an interaction. A significant interaction would signal that enzymes matter more with one leaf source than the other. The design does not, on its own, benchmark leaf powders against synthetic pigmenters such as apoester or canthaxanthin. It also does not address drug-style regulatory questions: both leaf meals fall under feed-ingredient rules, while the underlying enzymes are regulated feed additives with EU and U.S. approvals. The source does not list sample size, replicate pen numbers, or statistical model, so any conclusion about treatment means is premature.

Practice-level read

Producers evaluating cost-effective yolk colorants now have one more data point. If the trial shows a yolk color lift without an egg-production or feed-conversion penalty, leaf-powder-plus-enzyme combinations move from research curiosity to candidate ration strategy for older flocks. Watch for follow-up papers with longer feeding periods, dose-response work, and oxalate-level reporting. Oxalate content in Rumex is the main safety lever for laying hens, since soluble oxalate can depress calcium availability and eggshell quality. The full text should land on the Poultry Science website by the December 2026 issue date with sample sizes, treatment means, and the interaction term that determines commercial relevance.