PARTNER FEATURE ▶▶▶
Beneficial effect of probiotics on calcium metabolism
As the laying cycle progresses, eggs get bigger while the hens’ calcium (Ca) metabolism becomes less efficient. This leads to worsening eggshell quality as hens age. The capacity to keep hens well beyond 90 weeks emphasizes the need to manage eggshell quality all along the cycle to avoid some end-of-lay disorders.
BY JEAN-BAPTISTE SOULA, FLORENCE BARBÉ, LALLEMAND ANIMAL NUTRITION A
dvances in genetics and management practices have brought major progress in term of eggshell quality and strength. All the Ca deposited on the eggshell comes from the feed. Therefore, its assim-
ilation and mineralization also relies on the bird’s digestive health status. Complementary nutritional strategies, such as probiotics that help support gut health, have a role to play in enhancing eggshell quality and the subsequent bone health status of laying hens, as confirmed by recent studies.
Demanding mineralization process Eggshell mostly consists of calcium carbonate (94-98%) in calcite mineral form. Its quality mainly depends on the bird’s genetics and physiology (age, health), farm management practices (production system, lighting) and nutrition. Egg- shell formation is a complex and rapid biomineralization process that takes place nightly in the uterine gland. It is completed between 60 to 90 minutes before oviposition and it leads to the synthesis of ~6g of shell in less than 20 hours! This mineralization process, one of the fastest in the world, involves more than 600 genes coding for 400 proteins.
Figure 1 – Desynchronization between Ca intakes and needs for eggshell formation.
✘
Ca availability Bone storage > mobilization Shell mineralization
✘
Ca intake Bone mobilization > storage Shell mineralization
Calcium requirements increase with the age but should be carefully managed from the pullet stage, a critical moment for the development of the medullary bone Ca reservoir. During egg production, this reserve is mobilized into the uterine gland. When blood Ca levels become critical, a Ca resorption process from bones is initiated. The complexity of the shell mineralization process is due to two factors: that this intense and brief activity does not rely on any Ca reserve in the uterus, and the Ca needed for eggshell deposition in the uterus during the dark period occurs in the absence of dietary intake. The desynchronization (Figure 1) and the scale of this miner- alization process (~2g of Ca/egg) results in the subsequent export of Ca for the hen organism. Any Ca supply or metabo- lism deficiency can impair eggshell quality, the bone miner- alization processes and later affect bone health. Calcium me- tabolism in laying hens is regulated by environmental (light) and biochemical (minerals, vitamin and hormones) stimuli. During the day, part of the dietary Ca is absorbed in the small intestine through complementary pathways, while during the dark period, bone reserves are mobilized with the same type of pathways involved from the blood to the uterine cells. These active Ca pathways are regulated by the calcitriol hor- mone, the active form of vitamin D, and by the parathyroid hormone (PTH).
Potential of probiotic The probiotic bacteria Pediococcus acidilactici CNCM I-4622 (Bactocell) enhances birds’ digestive and protective functions through the stimulation of lactic acid bacteria populations. It has been shown to improve eggshell thickness and reduce the number of eggs rejected in various production systems. Extended laying cycles beyond the typical 90 weeks under- line the necessity to have a better understanding of how the probiotic interacts with Ca metabolism. A trial performed at Dankook University, South Korea, and presented at World Poultry Congress 2022 in Parisinvestigated original parame- ters, such as hormonal and mineral blood and bone markers in relatively mature hens. In this study a group of 50-week- old Hy-line brown laying hens was used, divided in 2 groups and fed with diets formulated according to genetic recom- mendations, except a 10% suboptimum level of Ca and P. Egg production and shell quality parameters were recorded for 14 weeks. Results confirmed the previously observed positive ef- fect of the probiotic on egg production (Figure 2) and egg
30 ▶ POULTRY WORLD | No. 7, 2022
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
