PHOTO: HERBERT WIGGERMAN
weight (+1%; p<0.05) (data not shown). This increased pro- duction partially came from a significant reduction in the re- jected eggs criterion and, notably, a positive effect on the broken percentage (-40%).
Probiotic and calcium metabolism To gain a clearer understanding of the positive effect of the probiotic on eggshell quality, Ca and P retentions were measured. This criteria represents the difference between the amount of nutrients ingested by the animal via the feed and the nutrients found in the faeces. Starting with similar retentions at week 1, both the Ca and P retentions improved after the 14-week Bactocell supplementation (Figure 3): this reflects better utilization of the dietary mineral sources which support eggshell quality. To more thoroughly understand the mode of action of the probiotic in terms of dietary Ca utilization, hormonal ac- tivities related to Ca metabolism were analysed. Calcitriol blood concentration increased by 83% after the 14-week treatment compared with the control group. It was hypothe- sized that the probiotic bacteria favoured the production of calcitriol throughout the hens’ lifespan, thus supporting Ca mobilization from dietary origin. With extended production cycles and Ca metabolism fatigue, bone structure damage is predictable. In this trial, probiotic supplementation showed stimulation of calcitriol activity in the advanced hen laying cycle (>50 weeks). This resulted in better Ca dietary absorption without affecting bone mineral content (Figure 4). It is assumed that the higher Ca serum concentration in the context of a low calcium diet was used by the shell gland in the uterus to build a stronger eggshell compared to the control group of laying hens. Even more re- markable about these results is that the hens in the probiotic group laid heavier eggs compared to the control group and, as such, must have exported more Ca. Finally, at the end of the trial, a better bone structure was also observed.
New insights The trial provided new insight into the probiotic benefits of P. acidilactici CNCM I-4622 on Ca metabolism in birds, with a beneficial effect on eggshell quality. A reduction in rejected eggs was confirmed in 50-week-old layers. This effect is likely due to the stimulation of calcitriol activity, triggering dietary Ca retention. Limited incidence of Ca-metabolic disruption of the bone status in mature hens was also highlighted. To- gether with the previously described beneficial effects of P. acidilactici on egg production (laying rate, persistency) and hen welfare (faeces quality, mortality), these benefits for egg- shell and bone integrity represent complementary economic and welfare reasons to consider the use of this probiotic in egg production.
References available on request.
Figure 2 – Effect of BACTOCELL on the exported egg mass (p=0.009).
Marketable Exported Egg Mass (wk 1-14; g/hen/wk.)
432.6 Control
437.1 Bactocell
Figure 3 – Effect of BACTOCELL on Ca and P retentions (%; p<0.05).
Ca And P Mineral Retentions (at wk. 14; %)
+ 4.2 pts 45.53
41.3
+ 4.1 pts 49.68
45.53 Control Bactocell
The probi- otic bacteria Pediococcus acidilactici has been shown to improve egg- shell thickness and reduce the number of eggs rejected in vari- ous production systems.
Ca
P
Figure 4 – Ash bone content (%). Bone Ash (%)
54.54 52.24 Control 46.87 Bactocell 46.07
Week 1
Week 14 ▶ POULTRY WORLD | No. 7, 2022 31
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