GSE137690
Enhanced pre-pubertal nutrition upregulates mitochondrial function in the testes and sperm of post-pubertal Holstein bulls
Recent studies have documented the profound impact of pre-pubertal nutrition on reproductive performance in bulls. Previously, a high plane of nutrition during calfhood (2-30 wk) in beef and dairy bulls hastened puberty explained by an increase in the level of reproductive hormones (LH, testosterone and IGF-I) pre-pubertally, compared to bulls fed less than recommended amounts of energy and protein with no apparent effect on sperm function evaluated by traditional techniques. In addition, upregulated steroid biosynthesis and Sertoli cell maturation was identified in the testicular tissue of high diet bulls at 16 and 24 weeks, respectively. The objective of this study was to evaluate the post- pubertal testes for responses to high (20.0% CP, 67.9% TDN), medium (17.0% CP, 66.0% TDN) and low (12.2% CP, 62.9% TDN) diets fed from 2-30 wk of life. Based on RNA sequencing data, 497 genes were differentially expressed in high vs low diet and 2961 genes in high vs medium diet (P<0.1). According to KEGG analysis, oxidative phosphorylation and ribosome pathways were upregulated in the high diet group (vs medium and low) with majority of the upregulated genes encoding for essential subunits of complex I, III, IV and V of OXYPHOS pathway. In addition, mitochondrial translation, mitotic nuclear division and cell division were enriched in the high vs medium diet group. Supporting the above, the percentage of sperm exhibiting loss of mitochondrial function was lower in the high diet compared to the medium diet (P<0.1). Thus, enhanced early life nutrition upregulated mitochondrial function in both the testes and sperm of post-pubertal Holstein bulls. Overall design: Holstein bull calves (n=24) maintained on either a high, medium or low diet from 2-32 wk of age, were castrated at 72 wk, testicular mRNA extracted and sequenced.