Pre- and post-partum mild underfeeding influences gene expression in the reproductive tract of cyclic dairy cows.

Undernutrition before and after calving has a detrimental effect on the fertility of dairy cows. The effect of nutritional stress was previously reported to influence gene expression in key tissues for metabolic health and reproduction such as the liver and the genital tract early after calving, but not at breeding, that is, between 70 and 90 days post-partum. This study investigated the effects of pre- and post-partum mild underfeeding on global gene expression in the oviduct, endometrium and corpus luteum of eight multiparous Holstein cows during the early and middle phases of an induced cycle 80 days post-partum. Four control cows received 100% of energy and protein requirements during the dry period and after calving, while four underfed received 80% of control diet. Oestrous synchronization treatment was used to induce ovulation on D80 post-partum. Oviducts, ovaries and the anterior part of each uterine horn were recovered surgically 4, 8, 12 and 15 days after ovulation. Corpora lutea were dissected from the ovaries, and the endometrium was separated from the stroma and myometrium in each uterine horn. The oviduct segments were comprised of ampulla and isthmus. RNAs from ipsi- and contralateral samples were pooled on an equal weight basis. In each tissue, gene expression was assessed on a custom bovine 10K array. No differentially expressed gene (DEG) in the corpus luteum was identified between underfed and control, conversely to 293 DEGs in the oviduct vs 1 in the endometrium under a false discovery rate (FDR) < 0.10 and 1370 DEGs vs 3, respectively, under FDR < 0.15. Additionally, we used dedicated statistics (regularized canonical correlation analysis) to correlate the post-partum patterns of six plasma metabolites and hormones related to energy metabolism measured weekly between calving and D80 with gene expression. High correlations were observed between post-partum patterns of IGF-1, insulin, β-hydroxybutyrate and the expression in the oviduct of genes related to reproductive system disease, connective tissue disorders and metabolic disease. Moreover, we found special interest in the literature to retinoic acid-related genes (e.g. FABP5/CRABP2) that might indicate abnormalities in post-partum tissue repair mechanisms. In conclusion, this experiment highlights relationships between underfeeding and gene expression in the oviduct and endometrium after ovulation in cyclic Holstein cows. This might help to explain the effect of mild undernutrition on fertilization failure and early embryonic mortality in post-partum dairy cows.