TY - JOUR TI - Milk-borne bioactive factors DO - https://doi.org/doi:10.7282/T3C53J57 PY - 2014 AB - Milk-borne bioactive factors (MbFs) are delivered to nursing offspring via a lactocrine mechanism to affect development of somatic tissues, including the uterus. In the pig, lactocrine-sensitive events associated with postnatal uterine development between birth (postnatal day = PND 0) and PND 2 define the developmental program and can determine developmental trajectory and function. However, lactocrine-sensitive elements of the neonatal porcine uterine transcriptome have not been defined during this period. The extent to which MbFs, including insulin-like growth factor (IGF)-I, affect development of the porcine uterus postnatally is unknown. Furthermore, whether nursing supports testicular development in pigs by PND 2 remains to be determined. Research goals were to (1) define the lactocrine-sensitive uterine transcriptome in nursed gilts compared to animals fed replacer from birth until PND 2; (2) determine whether feeding colostrum, with or without IGF-I supplementation, supports endometrial cell proliferation at 12 h postnatal; and (3) assess whether nursing affects Sertoli and Leydig cell development as well as expression of markers important for testicular development within two days after birth. Results showed that in uteri of nursed as compared to replacer-fed gilts, 896 genes were differentially expressed and multiple elements of biological processes and pathways affected by PND 2. Additionally, data indicated that when compared to replacer-fed gilts, a single dose of colostrum at birth increased endometrial cell proliferation at 12 h postnatal. Furthermore, oral IGF-I increased uterine cell proliferation when co-administered with replacer, but not with colostrum. Sertoli cell number and proliferation were increased in boars nursed for two days compared to newborn or replacer-fed boars at PND 2. However, testicular RXFP1 expression was increased in replacer-fed animals as compared to boars collected at birth or after two days of nursing. Collectively, data presented here reinforce and extend previous findings that lactocrine signaling supports neonatal porcine reproductive development. Results can be used to refine and focus the lactocrine hypothesis to identify key MbFs as well as cellular and molecular mechanisms that regulate postnatal male and female reproductive development in the pig. KW - Animal Sciences KW - Milk--Composition KW - Testis KW - Swine--Development--Endocrine aspects KW - Biotransformation (Metabolism) LA - eng ER -