Date of Graduation

8-2011

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Cell & Molecular Biology

Advisor/Mentor

Rosenkrans, Charles F. Jr.

Committee Member

Kreider, David L.

Second Committee Member

Kown, Young M.

Third Committee Member

Lessner, Daniel J.

Keywords

Biological sciences; Beef cows; Body condition; Haplotypes; Lactate dehydrogenase; Production; Single nucleotide polymorphisms

Abstract

Lactate dehydrogenase (LDH) catalyzes the conversion of the pyruvate to lactate (forward) or lactate to pyruvate (reverse) in the last step of glycolysis. Objectives were to document the effects of LDH haplotypes and its SNPs, found in the promoter and coding sequence site, and body condition on beef cow production. Four single nucleotide polymorphisms (SNP) of LDH-B and Five single nucleotide polymorphisms of LDH-A were detected. Eight haplotypes of LDH-B were assigned with the same order of SNPs: G-348A, A-261G, N-222D, and C541A and four haplotypes of LDH-A were assigned with the same order of SNPs: T-327G, D-263C, G390A, A406G, and T530C. Specific primers were designed for polymerase chain reaction and amplification of 507-base pair (bp) fragment and 555-base pair (bp) fragment and 452-base pair fragment and 457-base pair fragments of the bovine LDH-A and LDH-B coding sequence and promoter, respectively. Brahman-influenced cows (n = 109) were managed to achieve either low (BCS = 4.3± 0.1) or moderate (BCS = 6.4± 0.1) body condition. Cows grazed stockpiled and spring growth, endophyte-infected tall fescue pastures prior to 60-d breeding period to obtain desired BC; serum samples collected on d -35. The results of LDH-B gene showed that cows that were heterozygous (GA) had a lower calving rate than homozygous with the major allele (53.3 vs. 79.1 %, respectively) at base position G-348A. In addition, IGF-I was affected (P < 0.05) by body condition and G-348A. A-261G had an effect (P < 0.05) on LDHf and follicle size. Deletion of six nucleotides (GGCCGC) was detected at base N-222D. LDHf of fifty-five cows that were either hetero or homozygous for the deletion was affected (P < 0.02) by the N-222D. Interaction between BC x C541A had an effect (P < 0.05) on LDHr. NEFA (non essential fatty acid) was affected (P < 0.02) by base position C541A. the results of LDH-A showed that NEFA were affected (P < 0.02) by T-327G. Deletion of six nucleotides (GGCCGC) was detected at base D-263C with an insertion of cytosine. LDHf and LDHr of LDH-A were not affected (P >0.10) neither by the genotypes nor by BCS. However, the interaction between BCS and D-263C affected (P< 0.05) LDHf. Haplotype 1 had the same sequence as that published at GenBank "No SNP". Haplotypes of LDH-A had no effect on both LDHf and LDHr (P >0.10), while the interaction between BCS X haplotypes had an effect on LDHf. Calving date was not affected by genotypes nor by haplotypes. In contrast, haplotypes of LDH-B had an effect on LDHf (P < 0.05). IGF-I, PRL, T3, and T4 were significantly affected by BCS. Our results demonstrated that the polymorphism of the coding sequence and promoter region can be used as a genetic marker for the selection of cows with high fertility.

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