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Impact of PrimaLacĀ® on gut health, and egg quality from free-range hens in late cycle 89 to 109 weeks of age


R.D. Malheiros, R. Crivellari, K.E. Anderson

 Prestage Poultry Science Department, NCSU, Raleigh, NC.


Probiotics are used as feed additives to improve the gastrointestinal tract of poultry. In free-range chickens it is common to have an intestinal parasite infestation (PInf). Better intestinal morphology is connected with better animal performance. This study was to evaluate PrimaLac (Star-Labs, Clarksdale, MO), in hens in their late stage of production, and to measure intestinal health, egg quality, and production criteria. The study was conducted at the NCDA Station, Salisbury, NC. We used 400 commercial hens, during late cycle, housed in a free-range system, divided in two treatment groups of 200 hens for each group, 50 hens per replicate. Four replicates of control feed and four replicates provided PrimaLac at 3 lbs./ton, fed ad libitum.  Egg production and mortality data were collected from 89 to 109 weeks of age.  In each period eggs were evaluated for external and internal egg quality.  At 109 wks. 10 hens/replicate were euthanized for tissue sample and PInf. evaluation. The trial was a completely randomized design. Student’s T test was used to compare PrimaLac® vs. Control, and Chi Square was used to compare the PInf.  Overall PrimaLac had greater HH% (56.54 vs 50.30), Daily Egg Mass (40.33 vs 37.17 g egg/d), and better feed conversion (.359 vs .310 g egg/g feed). The mortality was lower in the PrimaLac® group (P>0.05). Looking at internal egg quality, the vitelline membrane elasticity was better in PrimaLac® hens (5.23 vs 4.85 mm). The intestinal villi high (vh), tip wide (tw), bottom wide (bw), crypt depth (cd), muscular thickness (mt), globet cells count (gc), vh/cd, and villi surface (vs) were not affected by the inclusion of the DFM.


 The round worm population was lower in the PrimaLac® hens. Cecal worms were shown to have a significant reduction (P=0.0396) in the PrimaLac® hens.

In conclusion, the use of PrimaLac® in free-range hens in late cycle, has beneficial effects on eggs per HH%, on internal egg quality, and a strong reduction in the ceca parasite population in laying hens.