title: A calcitonin receptor (CALCR) single nucleotide polymorphism is associated with growth performance and bone integrity in response to dietary phosphorus deficiency.
abstract: Although concerns over the environmental impact of excess P in the excreta from pig production and governmental regulations have driven research toward reducing dietary supplementation of P to swine diets for over a decade, recent dramatic increases in feed costs have further motivated researchers to identify means to further reduce dietary P supplementation. We have demonstrated that genetic background impacts P utilization in young pigs and have identified genetic polymorphisms in several target genes related to mineral utilization. In this study, we examined the impact of a SNP in the calcitonin receptor gene (CALCR) on P utilization in growing pigs. In Exp. 1, 36 gilts representing the 3 genotypes identified by this CALCR SNP (11, 12, and 22) were fed a P-adequate (PA) or a marginally P-deficient (approximately 20% less available P; PD) diet for 14 wk. As expected, P deficiency reduced plasma P concentration, bone strength, and mineral content (P < 0.05). However, the dietary P deficiency was mild enough to not affect the growth performance of these pigs. A genotype x dietary P interaction (P < 0.05) was observed in measures of bone integrity and mineral content, with the greatest reduction in bone strength and mineral content due to dietary P deficiency being associated with the allele 1. In Exp. 2, 168 pigs from a control line and low residual feed intake (RFI) line were genotyped for the CALCR SNP and fed a PA diet. As expected, pigs from the low RFI line consumed less feed but also gained less BW when compared with the control line (P < 0.05). Although ADFI did not differ between genotypes, pigs having the 11 genotype gained less BW (P < 0.05) than pigs having the 12 or 22 genotypes. Pigs of the 11 and 12 genotypes had bones that tolerated greater load when compared with animals having the 22 genotype (P < 0.05). A similar trend was observed in bone modulus and ash % (P < 0.10). These data are supportive of the association of this CALCR SNP with bone integrity and its response to dietary P restriction. Although the allele 1 is associated with greater bone integrity and mineral content during adequate P nutrition, it is also associated with the greatest loss in bone integrity and mineral content in response to dietary P restriction. Understanding the underlying genetic mechanisms that regulate P utilization may lead to novel strategies to produce more environmentally friendly pigs.
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh 27695, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Alexander
authors.forename: A
authors.initials: A
authors.lastname: Qu
authors.forename: S A
authors.initials: SA
authors.lastname: Cutler
authors.forename: A
authors.initials: A
authors.lastname: Mahajan
authors.forename: M F
authors.initials: MF
authors.lastname: Rothschild
authors.forename: W
authors.initials: W
authors.lastname: Cai
authors.forename: J C
authors.initials: JC
authors.lastname: Dekkers
authors.forename: C H
authors.initials: CH
authors.lastname: Stahl
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001835:Body Weight / Q000235:genetics / Q000502:physiology; D001842:Bone and Bones / Q000502:physiology*; D005260:Female; D005838:Genotype; D010758:Phosphorus / Q000097:blood / Q000172:deficiency*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics* / Q000502:physiology; D018003:Receptors, Calcitonin / Q000235:genetics* / Q000502:physiology; D013552:Swine / Q000235:genetics* / Q000254:growth & development / Q000502:physiology
chemical_list: D018003:Receptors, Calcitonin; D010758:Phosphorus; D000469:Alkaline Phosphatase