Effect of Bacillus subtilis PB6 (CLOSTATTM) on performance of laying hens.

Evelyne Delezie1*; Liesbet Thijs2; Luc Maertens1; S. Decampeneere1

1ILVO Animal Sciences Unit, Melle, Belgium, 2Kemin Europa N.V., Agri-Foods Division, Herentals, Belgium

*Corresponding author. Email:

Abstract

The objective of this trial was to determine the efficacy of Bacillus subtilis PB6 (strain Bacillus subtilis ATCC PTA-6737) on laying hens’ performance.The strain was provided as a premixture and named CLOSTATTM Dry. The zootechnical trial consisted of 2 dietary treatments with 8 replicates of 18 laying hens each. The dietary treatments consisted of a control diet (TrA) and the control diet supplemented with Bacillus subtilis PB6 at 1x108 CFU/kg feed (TrB). Laying hens (Lohmann brown), 21 weeks of age at the start of the experiment, were used in this trial. Laying hens given the Bacillus subtilis PB6 performed significantly better than the control group, resulting in a significantly higher laying rate (P=0.007), egg weight (P=0.036), daily egg mass (P<0.0001) and better feed conversion (P=0.005). The incidence of soft-shelled eggs and of dirty eggs was similar for all groups whereas the incidence of cracked eggs was significantly lower (P<0.0001) when laying hens were given the supplemented diet.

Key words: laying hens; probiotics; performance

Introduction

Bacillus subtilisPB6 (strain Bacillus subtilisATCC PTA-6737) is a unique and natural Bacillus subtilis strain and is a proprietary, spore forming, gram-positive bacterium. Bacillus subtilis ATCC PTA-6737 is authorized for chickens for fattening in feed legislation by Regulation (EC) 107/2010 under number 4b1823 in the category zootechnical additive and functional group of gut flora stabilizers.An objective measurement of the efficacy of new products is an essential step in the development of (cost) effective additives.

The objective of the current trial was to provide efficacy data of Bacillus subtilisPB6 for use in laying hens. The strain is supplemented with carrier i.e. maltodextrin and limestone and provided as a premixture, named CLOSTATTM Dry. For this purpose Bacillus subtilis PB6 was introduced in a basal diet. The bioefficacy of Bacillus subtilis PB6 for laying hens was determined in a performance trial.

Material and Methods

Laying hens (Lohmann brown), 21 weeks of age at the start of the experiment, were used in this trial. The birds were housed in the poultry experimental facility of ILVO/ Section Small Stock Husbandry.The trial consisted of 2 treatments, each with 8 replicates of 18 animals. Duration of the trial was 168 days as there were 6 periods of each 28 days. The trial was designed as a 2-factorial Complete Block Design (2treatments x 8 replicates = 16 pens) with 18 medium weight laying hens per pen with a total number of 288 birds. The test product, provided as a premixture having spore counts of 2 x 108 CFU/g, was dosed at a rate of 500g/tonne, which resulted in a dosage of 1 x 108 CFU/kg feed.The different treatments were:Treatment A =basal diet, Treatment B =basal diet + Bacillus subtilis PB6 (1 x 108 CFU/kg feed).

Average pen body weight was recorded at the start and at the end of the experiment. Feed intake was recorded and feed conversion and daily feed intake per bird were calculated for each period. Daily number of eggs per pen unit were counted and every 2 weeks eggs were weighed. Furthermore, every day the incidence of cracked, soft-shelled and dirty eggs was recorded.Daily mortality and cullings were recorded for each pen. Egg quality was measured in terms of egg shell deformation (under a 500 g load, in micrometer) at day 21 of each 28 d-period. All parameters were subjected to a factorial analysis of variance (“2 x 8 x 6 / 2 dietary treatments x 8 blocks x 6 period”) and the corresponding LSD-multiple range test (with P:0.05 as the threshold value).

Results and discussion

The main zootechnical results are presented in Table 1. There was no block (replicates) effect but a significant effect of period on laying rate, egg weight, daily egg mass and feed conversion was observed. Laying rate was significantly lower for the first period as hens were only 21 weeks of age. Egg weight and daily egg mass significantly increased with the age of the laying hens, therefore significantly higher egg weights and daily egg masses were reached at the end of the trial. Daily feed intake of the laying hens ranged from 111.53 to 116.22 g/hen with the highest feed intake during period 2 and 5. This resulted in a significant better feed conversion during period 6 and the worst feed conversion ratio was obtained during period 1 caused by the significantly lower laying rate. Supplementing the feed with Bacillus subtilis PB6 did affect the zootechnical parameters. Laying hens which received the supplemented diet showed a significantly higher laying rate,egg weight and daily egg mass compared to the control birds. Daily feed intake of both treatment groups did not differ significantlywhat resulted in a significant better feed conversion ratio for the birds given the Bacillus subtilis PB6 supplemented diet. The results of this trial are in line with results of previous in vivo trials in chickens for fattening showing positive effects on performance. An improved weight gain and feed efficiency of the chickens upon inclusion of Bacillus subtilis PB6 into the diet has been shown (Kemin data not shown). Furthermore, microbiological evaluation of the intestinal bacterial microflora of broilers has demonstrated that the counts of Clostridium perfringens decreased with increasing dosage of Bacillus subtilis PB6 in the feed (Teo and Tan 2004). Egg shell deformation was determined as a measure for egg quality. Supplementing Bacillus subtilis PB6 (Tr B) did result in the significantly highest egg shell deformation. There was also a significant effect of period with the lowest egg shell deformation during period 3 and the highest during period 1.The number or % of dirty eggs was very low and comparable between treatments. There was also no effect of dietary treatment on percentage soft-shelled eggs. Percentage soft-shelled eggs was 0.52 and 0.47% if laying hens received the control and supplemented diet, respectively. However, the incidence of cracked eggs was significantly lower (P<0.0001) when laying hens were given the supplemented diet (2.42 vs 1.34 %).At the start and at the end of the trial mean hen weight was similar for all dietary treatments. Therefore, growth of the laying hens for both treatments was not significantly different during the whole duration of the experiment. Also, mortality percentage was not different between treatments and periods.

Conclusion

Positive effects of Bacillus subtilis PB6 on the overall performance parameters in this layer study were present and did reach the significance level (P < 0.05).

References:

Teo A Y. H-M Tan. 2004. The effect of CloSTAT on pathogenic and beneficial bacteria in broilers. ProceedingsXXII World Poult. Congress, Istanbul, Turkey.p.174.

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Table 1. The effect of dietary treatment and period on laying rate (%), egg weight (g), daily egg mass (g), daily feed intake (g/a) and feed conversion
Treatment / Laying rate, % / Egg weight, g / Daily egg mass, g / Daily feed intake, g/a / Feed conversion
Treatment / Control / 90.84b / 62.61b / 57.06b / 113.24 / 2.02b
Control + CLOSTATTM / 93.19a / 63.04a / 58.93a / 114.60 / 1.97a
SEM / 0.80 / 0.35 / 0.74 / 0.51 / 0.03
Period / 1 / 78.52b / 56.94d / 44.73c / 111.53 / 2.51b
2 / 96.13a / 62.46c / 60.04b / 114.95 / 1.91a
3 / 94.60a / 63.88bc / 60.44ab / 112.59 / 1.87a
4 / 96.00a / 64.09b / 61.53ab / 113.01 / 1.84a
5 / 95.81a / 64.51b / 61.81ab / 116.22 / 1.88a
6 / 94.58a / 66.79a / 63.16a / 113.96 / 1.81a
SEM / 0.80 / 0.35 / 0.74 / 0.51 / 0.03
ANOVA
Period / < 0.0001 / < 0.0001 / < 0.0001 / NS / < 0.0001
Treatment / 0.0007 / 0.036 / < 0.0001 / NS / 0.005
Period x Treatment / NS / NS / NS / NS / NS
a-cmeans with the same letter are not significantly different from each other at P ≤ .05.