South African researchers studied the effects of two different feeding regimes on the reproductive characteristics of young Dorper rams (~15 months old).
Rams in the first group (n=16) were fed ad libitum intensively on a diet for 7 weeks, while the second group (n=16) was maintained on natural pastures with lick tub supplementation.
At the end of the trial period, semen was collected from each ram via electro-ejaculation and evaluated. Following slaughter of the rams, the scrotums were excised and dissected. Semen, scrotal, testicular and carcass characteristics were compared.
Nutritional management had an influence on scrotal circumference, scrotal weight, scrotal fat, testes weight and volume. Intensively-fed rams had significantly greater scrotal circumference and signficiantly more fat deposits (particularly in the scrotal neck) compared to the extensively-managed rams. Overall and mass sperm motility was superior in the extensively-managed rams.
The researchers concluded that overfeeding young rams could be detrimental to their fertility.
Source: Small Ruminant Research Journal. August 2004.