Nutritional and Physiological Responses of Sudan Desert Sheep and Nubian Goats to Water Restriction

Abstract

This study was conducted to compare the nutrient utilization,
concentration of some rumen metabolites, blood urea nitrogen and some
physiological responses to water restriction in Sudan desert sheep and
Nubian goats. Three yearling uncastrated intact males from each species,
averaging 18.37 kg (for sheep) and 13.21 kg (for goats), were randomly
allotted to four treatments in a completely randomized block design with
a 2 x 2 factorial arrangement of treatments to determine the effects of
animal species and water restriction. Both species were offered either ad
libitum feed and water or water restricted to 50% of ad libitum level with
ad libitum feed. Animal species resulted in a significant (P<0.01) increase
in dry matter intake, water intake, faecal dry matter and respiration rate
and a decrease (P<0.01) in water intake: dry matter intake ratio in sheep
compared with goats. Sheep showed also higher (P<0.05) urine volume
value than goats. Rectal temperature was not affected by animal species.
Dry matter intake, faecal dry matter and urine volume decreased
insignificantly with water restriction. However, water intake and water
intake: dry matter intake ratio decreased significantly (P<0.01) with
treatment. Rectal temperature and respiration rate values were almost
similar at the two levels of water intake. Species x treatment interaction
showed a significant (P<0.01) increase in water intake in sheep compared
with goats given water ad libitum. Water intake, however, decreased in
both species as a result of water restriction. Animal species induced a
significant effect on the apparent digestibility coefficients of dry matter,
organic matter, crude protein, crude fibre, nitrogen free extract and total
digestible nutrients. Ether extract digestibility did not differ between
species. Goats had lower digestibility coefficients and total digestible
nutrients compared with sheep. Except for ether extract digestibility, the

   

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Sulafa M. H. Hassouna and Asim A. A. Lutfi
digestibility coefficients of nutrients as well as total digestible nutrients
increased with water restriction. Sheep had the highest nitrogen balance
value. Nitrogen balance showed similar trend whether it is expressed as a
percentage of nitrogen intake or digested nitrogen. Species x treatment
interactions were not found for digestibility and nitrogen balance data.
Rumen pH and ammonia nitrogen were not affected significantly by
species. Water restriction did not induce a significant effect on rumen pH
and blood urea nitrogen. A significant species and treatment effect on
blood urea nitrogen and ammonia nitrogen, respectively, was recorded.