Can you improve egg quality and lower the cholesterol content of the yolk?

A scientific trial with young laying hens was performed in the University of Warmia and Mazury, Olsztyn, Poland. The objective of this study was to determine the effect of a probiotic preparation containing Bacillus subtilis ATCC PTA-6737 (CLOSTAT®) on selected egg production parameters, egg quality, the fatty acid profile and cholesterol content of egg yolk.

Animals and dietary treatments
The experimental materials comprised 288 Lohmann Brown laying hens aged 16 weeks, raised in accordance with the recommendations. The hens were reared for 26 weeks, including a two-week pre-laying period (the experiment started when 20% of the hens were in lay).

Production parameters and egg quality
The birds were weighed at the beginning (18 weeks of age) and at the end (42 weeks of age) of the trial. Eggs were collected from each cage six times per week to determine the total number of eggs laid. The average weight of eggs laid was determined by weighing eggs from each cage every week. Feed intake and feed conversion were recorded at four-week intervals.

Egg quality was analysed at four-week intervals (week 4, 8, 12, 16, 20 and 24 of the laying period). Freshly laid eggs were collected on the first day of a given period. Each time egg quality was evaluated on 15 eggs per group selected randomly based on the average egg weight for a given experimental period. Eggshell thickness and breaking strength, yolk colour, albumen quality (Haugh unit score) and the percentage of egg components were determined.

Total egg weight, yolk weight and eggshell weight (including shell membranes) were determined individually with an accuracy of ± 0.01 g.

Cholesterol content of egg yolk
Cholesterol concentrations were determined based on IDF Standard (1992). The cholesterol content of yolk was expressed as milligrams per gram of yolk lipids.


Table 1. Production parameters of the laying hens over the 24 week trial period

Table 2. Effect of dietary CLOSTAT on egg quality over the 24 week trial period

Table 3. Effect of dietary CLOSTAT on Body Weight Gain and yolk cholesterol content at 42 weeks of age


1. No significant differences in the production performance was registered although an increase of egg weight (+0.5 g) was noticed.

2. The improvements of the egg quality parameters like shell thickness (+0.01 mm), shell strength (+2.51 N), yolk colour (+1.18 points), Haugh units (+2.50) and shell as % in the egg composition (+0.25%) are highly significant.

3. The cholesterol content in the egg yolk decreased by -3.3 mg/g.

These data show that CLOSTAT causes a significant improvement of several egg quality parameters. Together with the significant improvement of the body weight gain (+46 g extra) over the 24 week trial period, this is a clear indication that the digestion and absorption of the nutrients needed for growth and egg production are improved by CLOSTAT.


1. The effect of a probiotic preparation containing Bacillus subtilis ATCC PTA-6737 on egg production and physiological parameters of laying hens. Alicja Sobczak, Krzysztof Kozłowski (Ann. Anim. Sci., Vol. 15, No. 3 (2015) 711–723 DOI: 10.1515/aoas-2015-0040)

2. Kemin Internal reference: TD-13-00337