|ANGEL, ROSELINA - University Of Maryland|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2018
Publication Date: 12/3/2018
Citation: Proszkowiec-Wegla, M.K., Schreier, L.L., Miska, K.B., Angel, R., Kahl, S., Russell, B.A. 2018. Effect of early neonatal development and delayed feeding immediately post-hatch on jejunal and ileal calcium and phosphorus transporter genes expression in broiler chickens. Poultry Science. 98:1861-1871. http://dx.doi.org/10.3382/ps/pey546.
Interpretive Summary: Calcium and phosphorus are essential minerals involved in many physiological processes including metabolic pathways and mineralization of the bones. Plasma concentration of both minerals is tightly regulated within narrow physiological ranges through feedback mechanisms consisting of parathyroid hormone, active form of vitamin D3, calcitonin, and their respective receptors localized in the small intestine, bones and kidneys. In general, calcium and phosphorus homeostasis is maintained via intestinal absorption, storage and exchange with bones and renal excretion or reabsorption. In the current broiler production systems, chicks are deprived of food and water for up to 72 hours due to uneven hatching, hatchery procedures such as sexing, sorting, selection and vaccination, and transportation time to destination farms. Lack of access to feed during the first 48-72 hours results in lower body and organ weight, higher feed conversion ratio (amount of feed required for 1kg of body weight gain) and mortality, delayed growth rate and gastrointestinal tract development. Little is known about the effects of a delayed feed access post-hatch on calcium and phosphorus transporters. It is well known, that insufficient supply of one or both minerals results in reduced growth rate and bone mineralization leading to skeletal abnormalities, lameness, and increased morbidity and mortality in fast growing broilers. Therefore, the aim of the present study was to characterize expression patterns of small intestine calcium and phosphorus transporter genes during the first two weeks post-hatch in chickens. To mimic commercial settings, newly hatched chicks were subjected to 48 hours delay in feeding or fed immediately after hatch. We have determined that: 1) expression of all calcium and phosphorus transporters in small intestine (jejunum and ileum) were affected by age, 2) only mRNA expression of calcium transporter Calbidin D28k in jejunum, and calcium sensing receptor in ileum were effected by delay in feed access, and 3) only phosphorus transporter type III was affected by age, delay in feed access and their interaction. In summary, we have shown, for the first-time, developmental changes in expression of calcium and phosphorus transporter genes in broiler chickens. The lack of effect of delayed feeding on the expression of some transporter genes could be related to the adequate presence of calcium and phosphorus accumulated in yolk sack that provides a minimum requirement during this short period. Overall, our results can be helpful in better understand of calcium and phosphorus homeostasis in broilers.
Technical Abstract: Calcium (Ca) and phosphorus (P) are essential minerals involved in many biological processes including bone development and mineralization. Plasma concentration of both minerals is tightly regulated, and Ca and P homeostasis is maintained via intestinal absorption, bone storage and exchange, and renal reabsorption. In the current broiler production systems, chicks are deprived of food and water for up to 72 h due to uneven hatching, hatchery procedures and transportation time to farms. Post-hatch (PH) feed delay results in lower body and organ weight, higher feed conversion ratio and mortality, and delayed PH growth and GIT development. Little is known about the effects of early neonatal development and delayed or immediate feeding PH on Ca and P transporters. Therefore, the aim of the present study was to characterize expression patterns of Ca and P transporter genes in small intestine during the first two weeks PH in chickens fed immediately after hatch (FED) or subjected to 48 h delayed feeding (NOTFED). Expression of all Ca and P transporters in jejunum and ileum were significantly (P<0.05) affected by age. Among Ca transporter genes, only mRNA expression of Calbidin D28k in jejunum, and Ca sensing receptor (CaSR) in ileum were significantly (P<0.05) affected by delay in feed access. For P transporter genes expression, only P transporter type III (PIT1) mRNA was significantly affected by age, delay in feed access and their interaction (P<0.05). In summary, we have shown, for the first-time, developmental changes of Ca and P transporter genes in broiler chickens. Results suggest that increase in gene expression of some of the transporters corresponds with the switch from yolk to high starch diet. That the lack of effect of delayed feeding on expression of some transporter genes could be related to sufficient amount of Ca and P accumulated in yolk sack that provides a minimum requirement during this short period of time. Overall, our results can be helpful in better understanding Ca and P homeostasis in broilers.