Reproduction Abstracts

This study determined whether variation (representative of normal UK farm conditions) in pregnant ewe management is sufficient to alter the programing of the male reproductive axis. Between days 85 and 138 of pregnancy, twin-bearing ewes were managed to either mimic ‘poor husbandry’ (PH) with a high stocking density, reduced feeding space and repeated social mixing or according to ‘best practice’ (BP) with a lower stocking density, longer feed troughs, and stable social groups. Testes were collected from male offspring at 7 (pre-pubertal, n=10/prenatal treatment) and 19 weeks (puberty, n=8/prenatal treatment) of age, weighed and preserved for histology and gene expression analyses. Proliferation of testes cells was determined by immunohistochemical localisation of Ki-67 and counterstaining with haematoxylin. There was no treatment effect on lamb body weight at either age or on 7-week-old lamb testis weight or seminiferous tubule diameter. Testes from pubertal PH lambs were heavier (352±16 g vs 257±16 g; P=0.002), with a larger volume (39 219±3293 mm³ vs 29 498±2092 mm³; P=0.015) and increased seminiferous tubule diameter (Feret’s diameter=272.36±8.81 μm vs 246.81±5.24 μm; P=0.015) compared with BP lamb testes. Testes from BP lambs had more proliferating Leydig cells than PH lambs at both ages (7 weeks: 98±28 vs 35±20 stained cells/mm² and 19 weeks: 34±15 vs 18±4 stained cells/mm², respectively; P=0.025). PH lamb testes tended to have greater LH receptor expression, more Sertoli cells but fewer Leydig cells compared to contemporary BP lambs. These studies suggest that the range of husbandry conditions in current farming systems is sufficient to program male reproductive development.

Funded by Scottish Government, BBSRC and Edinburgh University.