Gonadal and extragonadal sperm reserves in Boran and Boran X Friesian bulls raised on two planes of nutrition in the highlands of Ethiopia

Gondal and extragonadal sperm reserves were determined in testicular and epididymis tissues obtained from Boran and Boran X Friesian bulls fed either a high or low plane of nutrition diet for a one-year period. The bulls were 32 months of age at castration. Mean body weights did not differ between Boran and Boran X Friesian bulls. Boran X Friesian bulls had significantly heavier testes, but epididymis weights did not differ between breeds. Although dairy sperm production per gram was not influenced by either plane of nutrition or breed, daily sperm production differed between high and low nutrition bulls and between Boran and Boran X Friesian bulls. Extragonadal sperm reserves were significantly higher in high than in low nutrition bulls and in Boran than Boran X Friesian bulls. The canda epidedymis contributed 50 to 54 percent to the total epididymis sperm reserves. It was concluded that the plane of nutrition influenced growth rates and testes and epididymis weights, and it improved gondal and extragonadal sperm reserves in young Boran and Boran X Friesian bulls.