Early-life conditioning strategies to reduce dietary phosphorus in broilers: underlying mechanisms

Abstract

<jats:title>Abstract</jats:title> <jats:p>Chickens adapt to P and Ca restriction during the very first days of life by improving P utilisation efficiency. The present study was built to identify the mechanisms underlying this adaptive capacity, and to identify the optimal window of application of the restriction (depletion). A total of 1600 Cobb 500<jats:sup>TM</jats:sup> male broilers were used. During each phase (from age 0 to 4 d, 5 to 8 d, 9 to 18 d and 19 to 33 d), the animals received either a control diet (H) or a restricted diet (L) with reduced levels of non-phytate P (nPP) and Ca (between −14 and −25 % for both) with four dietary sequences: HHHH, HLHL, LHHL and LLHL. None of the feeding strategies affected growth. Tibia ash content at day 4 and 8 was impaired when the L diet was fed from 0 to 4 and 5 to 8 d, respectively (<jats:italic>P</jats:italic> = 0⋅038 and <jats:italic>P</jats:italic> = 0⋅005). Whatever the early restriction period or length between 0 and 8 d of age, the mineralisation delay was compensated by day 18. This was accompanied by an increased mRNA expression of the Ca transporter, <jats:italic>CALB1</jats:italic>, and an increased apparent ileal digestibility of Ca at day 8 (<jats:italic>P</jats:italic> &lt; 0⋅001). This adaptation was limited to the starter phase in restricted birds. No effect was seen on P transporters mRNA or protein expression. In conclusion, birds adapted to mineral restriction by increasing Ca and nPP utilisation efficiencies. Depletion−repletion strategies are promising in improving the sustainability of broiler production but need to be validated in phytase-supplemented diets.</jats:p>

Dietary Phosphorus and Calcium Utilization in Growing Pigs: Requirements and Improvements

“…This allows an overall reduction in dietary P intake during the rearing phase. Depletion-repletion studies of growing animals such as pigs (8,10,136) and chickens (137)(138)(139)(140)(141) led to effectively increasing P utilization and limiting excretion without compromising animal well-being and performance. Some authors (9,142) have focused on improvements to bone health; these studies have led to better understanding of the deleterious effects of short-term dietary Ca deficits during growth on long-term bone mineralization.…”

CYP24A1 and TRPC3 Gene Expression in Kidneys and Their Involvement in Calcium and Phosphate Metabolism in Laying Hens

“…Furthermore, despite the differences in mineral levels, the expression of important functional genes, such as CALB1 and CALM2, remained unchanged, indicating the existence of mechanisms of compensation and adaptation to mineral utilization in chickens. This could help to mediate poultry health, mainly through mechanisms of long-term adaptive capacity, as has been suggested in broilers [75]. Finally, since mineral regulation mechanisms are not well described in laying hens' kidneys at molecular levels, our findings highlight the expression profiles of candidate genes in hens with advanced age, as well as their possible influence on production traits.…”

“…Although these genes are important for Ca and P regulation in the cell, the different levels of Ca/P provided in the diet did not influence their expression profile at 73 weeks of age, possibly because none of the levels used were considered deficient in the hens. Furthermore, these results could also be explained by diet adaptation since the laying hens received the same feed for a long time, indicating a compensation mechanism to maintain calcium absorption [75]. Probably, most of these genes would be differentially regulated in early ages when mineral renal physiology is more active [16].…”

SLC34A2 Targets in Calcium/Phosphorus Homeostasis of Mammary Gland and Involvement in Development of Clinical Mastitis in Dairy Cows

“…The PPI network displayed 12 candidate DEPs interacting with all selected GO terms, pathways, and DEPs, especially SLC34A2, indicating that these DEPs participate in the regulation of Ca/P metabolism and homeostasis via different routes. Previous studies have proved that Ca/P intake in birds adapted by increasing the mRNA expression of Ca transporters such as ATP2B1, SLC34A2, and SLC30A1 [34][35][36]. It was also reported that the regulation of mineral homeostasis including Ca/P metabolism was reflected via altered mRNA abundances of FTH1, FTL, and SP1, which were involved in phospholipase C, calcium signaling, nuclear factor of activated T cell signaling, and immunomodulatory implications [37,38].…”