Interactions between nutrition and reproduction in the management of the mature male ruminant

摘要: In mature male sheep and goats, changes in feed intake seem to have little effect on gonadal endocrine function but induce profound sperm production. These outcomes are due size of the seminiferous tubules spermatogenic efficiency. Except with severe underfeeding, there only minor testis (testosterone production) unless season-long treatments imposed. For cattle, nutrition clearly affects testicular development production spermatozoa young bulls, as it does other species but, after period rapid growth has ended, appears be or no response nutrition. We developing a clear picture metabolic signals, neuroendocrine processes hormonal control systems that involved, particularly for sheep. The energetic components diet, rather than protein, responsible, so we envisaged model relationship between energy balance reproduction 4 ‘dimensions’: genotype, structure (organs), communication (chemical neural nutrient sensing) time (dynamics, memory, programming). linked these perspectives ‘resource allocation theory’ incorporated them into strategies ‘clean, green ethical animal production’. contrast respect spermatogenesis, effects sexual behaviour more difficult define, perhaps because is affected by complex mix physiological factors flawed methods quantifying behaviour. example, compromised restriction, requires intensive motor activity decline libido could caused general weakness specific nutritional limitations. interaction feeding also complicates issue under field conditions. At end scale, overweight males can show reduced success they difficulty courting mounting. this reason, exercise enhance fertilising capacity rams. This will important extensive mating where need assemble guard harem then mate many times several weeks. artificial insemination centres, seems very few data management males, problems overfed animals appear risk. Future research should concentrate intra-testicular mediating spermatozoa.