Effects of water and feed restriction on body weight change and nitrogen balance in desert goats fed high and low quality forages.

The effects of water and food restriction on feed utilization, body weight changes and nitrogen balance were investigated in Sudanese desert goats given high or low quality forage. Nine male goats were employed in a 3x3 Latin square design where they were subjected to three treatments: ad libitum water and feed, ad-libitum feed/restricted water, and ad libitum water/restricted feed. These treatments were repeated using lucerne or sorghum hay. For both feed types dry matter intake (DMI) was not affected by treatments. Water intake decreased with feed restriction in goats fed sorghum hay. The ratio of water intake to DMI increased with lucerne hay compared to sorghum hay in both the control and feed restricted group. Water consumption increased with lucerne compared to sorghum hay. Body weight losses were more pronounced with water than with feed restriction but were less severe with lucerne than sorghum hay. Interactions due to treatment and feed type were significant for water intake and body weight change. With lucerne hay, except for crude protein (CP), nutrient digestibility improved with water restriction. Feeding sorghum hay, there were no effects on digestibility except for crude protein (CP) that was reduced with water restriction. Crude fiber (CF) and nitrogen free extract (NFE) digestibility increased with feed restriction in animals on sorghum hay. For all groups, CP digestibility was better with lucerne than sorghum hay. Interactions of the main effects were significant for all apparent digestibility coefficients as well as total digestible nutrients. The treatments did not have significant effects on nitrogen balance, however, nitrogen intake, retained or excreted in faeces was higher with lucerne than sorghum hay. It may be concluded that subjecting animals to water or feed restriction will have a more deleterious effect on feed utilization and nitrogen balance when using a low than a high quality forage.