Date of Award

8-2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Animal and Veterinary Sciences

Advisor

Long, Nathan M

Committee Member

Hill, Gary M

Committee Member

Strickland, James R

Committee Member

Pratt, Scott L

Abstract

Primiparous Angus-cross cows (n = 38) were synchronized using a Co-Synch+CIDR protocol and inseminated with semen from one of two Angus sires. Animals were fed at 1.3 x (Control [CON]) or 0.55 x (Nutrient Restricted [NR]) of maintenance energy and protein requirements based on BW (NRC 2000). Diets were fed at either 1.3 x (Control [CON]) or 0.55 x (Nutrient restricted [NR]) of maintenance energy and crude protein values based on BW (NRC 1996). A subset of animals (n = 16) was fed either NR (n = 8) or C (n = 8) from d 30-110 of gestation. The remaining animals (n = 22) were fed CON (n = 8) d 30-190; NR (n = 7) d 30-110 followed by CON d 110-190; or CON (n = 7) d 30-110 followed by NR d 110-190. Cows were slaughtered on d 110 or d 190 of gestation, when fetal measurements and samples were taken for analysis. Fetal weights and empty fetal weights were also reduced (P = 0.0027, P = 0.0023, respectively) in d 110 NR animals. Fetal weights tended to be reduced (P = 0.07) in NR/CON and CON/NR versus CON/CON cattle. Empty fetal weights were reduced (P = 0.03) in NR/CON and CON/NR versus CON/CON cattle. Abdominal and thoracic circumferences were reduced (P = 0.0265, P = 0.0002, respectively) in d 110 NR animals and were also reduced (P = 0.01 and P = 0.03, respectively) in NR/CON and CON/NR versus CON/CON cattle. Brain weight as a percent of empty fetal weight (P < 0.01) was increased in d 110 NR animals compared with d 110 CON animals. Brain weight as a percent of empty fetal weight was increased (P < 0.001) in NR/CON and CON/NR versus CON/CON cattle. Fetal pancreas weight as a percent of empty fetal weight was reduced (P = 0.06) in NR d 110 cattle. Fetal pancreas weight as a percent of empty fetal weight was reduced (P = 0.04) in CON/NR versus CON/CON cattle (0.062 ± 0.004 versus. 0.079 ± 0.004 %) while NR/CON values (0.069 ± 0.004 %) were intermediate. Fetal perirenal adipose as a percent of empty fetal weight was increased (P = 0.01) in NR d 110 female fetuses. Fetal perirenal adipose as a percent of empty fetal weight was increased (P = 0.003) in NR/CON and CON/NR versus CON/CON cattle. The data show that maternal nutrient restriction during early or mid gestation causes asymmetrical fetal growth restriction, regardless if the restriction is preceded or followed by a period of non-restriction. RNA was isolated from flash frozen cotyledon samples (3 subsamples/treatment) using the mirVana microRNA Isolation kit and analyzed using a previously validated microarray. MicroRNA expression was analyzed as an ANOVA analysis using appropriate procedures correcting for false discovery rate of microarray data. Of the sequences chosen for microarray, 88 showed significant (P < 0.05) differential expression between d 190 treatment groups. A total of 40 miRNAs were upregulated in the control group compared with both nutrient restricted groups and a total of 26 miRNAs were upregulated in the nutrient restricted groups compared with the control group. In d 110 animals, 142 showed significant (P < 0.05) differential expression between control and nutrient restricted groups. A total of 51 were upregulated in the control group versus the nutrient restricted group and a total of 91 miRNAs were upregulated in the nutrient restricted group versus the control group. In a comparison of d 110 and d 190 control animals, 139 sequences were (P < 0.05) differentially. A total of 57 miRNAs were upregulated for d 110 control fetuses and 82 miRNAs were upregulated for d 190 control fetuses. Of the 157 individual miRNAs, only 33 were available in TargetScan or picTar for predicted target analysis. Top KEGG pathway analysis included: Axon guidance, endocytosis, neuroactive ligand receptor interaction, MAPK signaling pathway, and spliceosomes. The data show that maternal nutrient restriction during early or mid gestation causes asymmetrical fetal growth restriction and affects miRNA regulation differently depending on whether or not the restriction is preceded or followed by a non-restriction period.

Share

COinS