The effect of level of water intake on some aspects of digestion and nitrogen metabolism of the ‘desert sheep’ of the Sudan

Abstract

Five successive trials were conducted using eight adult rams (Sudan desert sheep) to study the effect of restriction of water intake on some aspects of digestion and nitrogen metabolism. The feeds used in this study were berseem hay (Medicago sativa), lubia hay (Dolichos lablab), maize hay (Zea mais), a concentrate mixture, and dry desert grasses (hummra) (a mixture of Dactyloctenium aegyptium, Schoenefeldia gracilis, Eragrostis pilosa, Aristida funiculata and Aristida spp.).Restriction of water did not affect the digestibility coefficients of organic matter, crude protein and crude fibre significantly. The digestibility coefficient of ether extract was significantly reduced whereas that of nitrogen-free extract was slightly higher when water was restricted.The concentrations of ammonia and volatile fatty acids in the rumen and of urea in the blood were recorded before and 3 h after feeding. Increases in rumen ammonia and blood urea nitrogen concentration were reduced by water restriction except when hummra was fed.Restriction of water intake also slightly increased the in vitro rate of fermentation of rumen contents which is taken as a measure of microbial activity in the rumen, and the retention of nitrogen. These results are interpreted as indications of more efficient nitrogen utilization under conditions of water restriction.There were no significant effects of the treatments on changes in the concentration of volatile fatty acids.The significance of these findings in relation to the management of desert sheep in the arid parts of the Sudan is discussed with special reference to the effect of the level of dry-matter intake on nitrogen balance.

Effect of restricted water intake during summer on the digestibility of cell-wall constituents, nitrogen retention and water excretion in Marwari sheep

“…Throughout the experimental period, animals of both the groups remained in negative nitrogen balance, this being somewhat more pronounced in the water-restricted group. Similar observations have been reported by Thornton & Yates (1969) in cattle and by Osman & Fadlalla (1974) in Sudanese sheep. They concluded that as the feed intake is reduced due to the water restriction, nitrogen intake necessarily declines and, consequently, the relative proportion of endogenous nitrogen in the total amount of nitrogen excreted becomes greater.…”

“…and Utley, Bradley & Boling (1970) reported increased digestibility of crude fibre in water-restricted cattle; Purohit, Ghosh & Taneja (1976) made similar observations on the Marwaxi sheep of the Rajasthan desert. Osman & Fadlalla (1974) were, however, unable to find any change in the digestibility coefficient of crude fibre in water-restricted desert sheep of the Sudan. Increase in the digestibility of different feed components have been reportedly achieved in sheep by water deprivation for 48 h (Singh, More & Sahni, 1976).…”

Nitrogen metabolism in water-restricted Marwari sheep of the Indian desert

“…Reductions in urinary nitrogen and urinary urea The present study was conducted during October nitrogen excretion (Maloiy et al 1970) and increase 1979 in the Central Research Farm of this Institute in nitrogen retention (Osman & Fadlalla, 1974) have at Jodhpur (26° 05'N, 73° 01'E), located in the been observed in water-restricted sheep. Goodall & Indian desert.…”

Small Ruminants: Farmers’ Hope in a World Threatened by Water Scarcity

“…Goat fed legume hay had their feed intake reduced by 18.80% as compared to a reduction of 21.20% when a low protein content diet (meadow hay) was fed [77]. Similarly, Osman and Fadlalla [78] used eight adult water-restricted rams in five successive trials, which were fed different feeds ( Medicago sativa hay, Doclichos lablab hay, Zeamais hay, concentrate mixture and a mixture of dry desert grasses) and observed that animals that were fed the desert grass mixture had significantly lower dry matter intake (34.17%) than those that were fed Lucerne hay (8.00%). It has also been shown that Bedouin goats consumed more lucerne hay than wheat straw during dehydration [79].…”

“…Water restriction improves the digestibility of nutrients by increasing digesta retention time to allow more time for degradation by microbes and microbial synthesis [14,78]. Corriedale ewes that were water restricted for 2 and 3h after feeding had greater digestibility when compared to those that have access to water ad libitum after feeding [7].…”