Agricultural and Marine Sciences, 15:29-32 (2010) ©2010 Sultan Qaboos University 29 ____________________________ *E-mail: hmelhadi@hotmail.com Effect of Diet Quality and Housing on Water Status in Sudanese Desert Sheep and Goats Hashim Mohamed Elhadi* Department of Physiology, Faculty of Veterinary Medicine, University of Khartoum, Shambat, Sudan السودانیة الصحروایة والماعز األغنام في الماء حالة الغذاء واإلیواء على جودة تأثیر الھادي محمد ھاشم الماء) تحول ومعدل الجسم في الماء (مجموع الماء إیض لدراسة السودان في والماعز الصحراوي الضأن فیھما استخدم منفصلتین تجربتین ــراء إج تم الخالصة: ضأن استخدام تم الثانیة التجربة في الصحراویة. شبھ المنطقة في واإلیـــواء الرعي ــروف ظ تحت الــنــووي الماء باستخدام ــك وذل الجسم ــل داخ المیاه مواعین في المناخیة الظروف تحت الماء وأیــض المستقیم من الجسم حــرارة ودرجــة الجسم وزن قیاس تم الصحراویة. الحشائش أو البرسیم علف على غذیت وماعز صحراوي الرعي حیوانات في الماعز في الجسم حــرارة إرتفعت الحظائر. في إیواؤھا تم بالتي مقارنة الطبیعیة المراعي ترعى كانت التي الحیوانات أوزان إنخفضت الحارة. على یدل مما العالي الماء تدویر بمعدل مرتبطًا الماعز في اإلرتفاع وكان (٪٦) الضأن في أقل الحرارة درجة إرتفاع كان بینما إیواؤھا تم التي في عنھا ٪٩ بمقدار الجسم وزن على إیــواؤھــا تم التي الحیوانات حافظت التبخر. طریق عن التبرید على العتمادھا الضان من الــحــرارة تحمل على أقــل مقدرة لھا الحیوانات ھــذه أن تمیزت ــذي وال (البرسیم) الغني الغذاء من أقل میاه تناول بمعدل الصحراویة الحشائش أي الفقیر الغذاء إرتبط الــحــرارة. ــات درج إرتفاع ــراض أع علیھا تظھر ولم حیوانات في منھ أقل لكنھ فقیر غــذاء على تغذت التي الحیوانات في أعلى الخلیة خــارج المجال كان أعلى. غــذاء تناول ومعدالت أعلى میاه تدویر بمعدالت حیواناتھ البرسیم. على تغذت التي الحیوانات في أعلى الخلیة داخل المجال كان الرعي. ABSTRACT: Two independent experiments were carried out using Sudanese Desert sheep and goats to investigate water metabolism (total body water, TBW and water turnover, WTO) and internal water compartments using radioactive water (tritium), under natural grazing conditions in a semi-desert area. The second trial was carried out on confined sheep, fed high (Lucerne) and poor quality (desert grasses) diets. The body weights, rectal temperature and water parameters were monitored in both trials and species under the Sudanese summer conditions. The grazing animal’s body weights were reduced compared to confined ones. Hyperthermia was pronounced in goats (9%) compared to sheep (6%). The goat hyperthermia was associated with high water turnover, indicating the poor heat tolerance of this species of high evaporative cooling. The confined animals, however, maintained their body weights and did not show signs of hyperthermia. The poor diet (desert grasses) was associated with reduced water intake whereas the Lucerne was associated with high water turnover and high feed intake. The extracelluar compartment (ECV) was higher with the poor diet but was lower than the grazing group. The intracellular compartment (ICV) was higher in the Lucerne group. The study indicated that Sudanese Desert sheep are more tolerant to high temperatures and grazing system than goats. Introduction The Sudan has an area of one million square miles; half of this area is desert or semi-desert in the north of the country. The average rainfall is less than 75 mm or from 75 mm to 300 mm annually, in the desert and semi desert respectably. In the desert, apart from a few shrubs and grasses which spring- up after the rare showers, it is almost devoid of vegetation. However, in the semi-desert areas, the rains are erratic and unreliable and confined to the months of July and August. The vegetation consists of grasses, herbs and a scattered variety of shrubs and bushes. In such arid and semi-arid areas, the maximum temperature exceeds 35 oC and values of up of 46oC are not uncommon during May and June. The solar radiation reaches 550 cal/m2, however, the relative humidity is low, ranging from 10-30 %. Under such conditions, a huge area is unsuitable to livestock. However, in areas where the livestock can survive, the bulk of the sheep and goat population is maintained under nomadic husbandry systems. The migration of nomads in pursuit of water and pasture may be up to 200 km, while distances between grazing and watering points often exceed 40 km. The watering interval is 3-7 days, however F.D Islander (personal communications) indicated that 11 days interval in sheep in winter, is not uncommon. The ability of animals to survive, and indeed thrive under these harsh conditions, requires an extremely efficient adaptation, which may be reflected in their water usage and metabolism. Keywords : Sudan, desert sheep, goats, water turnover, water space. 30 Elhadi 31 Effect of diet quality and housing on water status in Sudanese desert sheep and goats There were approximately 51 million sheep and 43 million goats in the Sudan in 2007 (FAOSTAT, 2010). Desert sheep are the predominant breed in the country whereas the two major goat breeds are Desert goat and Nubian goat. However, despite the considerable importance of both sheep and goats to the livestock industry in the Sudan, there is a lack of information concerning the water requirements and metabolism of these animals, such information is needed for successful implementation of the livestock developmental schemes in areas where water is at a premium. Materials and Methods Approach The present study was an attempt to examine the water requirements and metabolism of sheep and goats, under the natural grazing and shaded confined conditions. The first trial was a comparison of the water and temperature parameters of sheep and goats under natural grazing practice in a semi-desert area about 10 km north of Khartoum. The second trial involved the influence of dietary quality on water metabolism and body fluid volumes in sheep maintained under confined conditions. Their total body water (TBW) and water turnover (WTO) measurements were monitored using radioactive water (Tritium–3H) and their relationship to their water intake, as measured by conventional methods. Animals In the first experiment, a total of 12 animals, comprising 6 desert rams, aged 2-3 years, and 6 Nubian bucks, aged 1-2 years, were used. The animals were kept in the semi-desert area (Latitude 15N) for 2 weeks before the investigation commenced. The meteorological data were collected by whirling hygrometer at 06:00, 13:00 and 17:00 hours, the mean air temperature was 20.3oC, 35.7oC and 33.5oC, respectively. The relative humidity remained at 35% during the experimental period. Rectal temperatures of animals were measured using a clinical thermometer. In the second experiment, twelve desert rams (weighing 23-34 kg) were divided into two groups, each group (6 sheep) was housed, in the semi-desert area, in two separate and similar semi -shaded pens. A period of 20 days was allowed for acclimatization to the feeding and watering regime followed by 10 days of collection period. Each group received either 6 kg of sun-dried chopped Lucerne or 6 kg of dry desert grass. The compositions of both types are given in Table 1. The food and water are offered in the morning (06:00) and their refusal or orts were weighed at 17:00 hours to calculate the amount consumed. Water Parameters The total body water (TBW) was determined using tritiated water (3H) and the dilution principle, the animals were injected at 5 pm using 2 ml of an isotonic solution of sodium chloride, containing 600 μ ci (sheep) or 400 μ ci (goats) given by deep intramuscular injection to each animal. The animals were then weighed; food and water were suspended till the following morning when the first blood sample was collected in heparinized tubes for radioassay. Subsequent blood samples were collected in the morning and evening for 10 days for the measurement of water turnover (WTO), plasma samples were prepared by adding 0.5 ml to 10 ml of “Instagel” (Packard) and tritium was assayed in a liquid scintillation spectrometer (Beckman). Similar measurements were made on the standard injected solution. The (TBW) was calculated by dividing the injected radioactivity by the plasma 3H concentrations 12 hours after injection and WTO was calculated by regression analysis of the plasma activities. Plasma volume was determined using Evans Blue dye (0.4 mg /kg) and ECV fluid volume was determined using (12 mg/kg) sodium thiocyanate. The ICV was calculated by difference (TBW- ECV) which included the rumen volume. A computerized (t-test) programme was used to test the significance of paired varieties in some parameters. Results and Discussion Experiment 1 During the 2 weeks period, the body weight of the grazing animals decreased slightly. The desert grasses were sparse and the animals had to walk about 5 km to and from the grazing area. The mean body weights of sheep decreased form 33.5±2.2 to 32.4±2.0 kg, and that of the goats decreased form 17.5±1.2 to 16.4±1.1kg. This reduction in body weights might indicate an adaptive feature which enables these desert animals to eat below maintenance requirements at such poor pastoral conditions. Similar findings in body solids changes were reported in grazing sheep (MacFarlane and Howard, 1970; Degen, 1977). The data in Table 2 indicated a diurnal variation in the body temperature of the grazing animals. Although both species experienced some degree of hyperthermia, associated with increased air temperature, this was greater in goats (9%) compared to in sheep (6%), indicating that goats are more predisposed to heat stress. The goat hyperthermia was associated with high water turnover (Table 3). The poor heat tolerance of the Nubian goats might be a reflection of the fact that this type of goat is not a true desert ruminant, as they are usually restricted to riverain and urban areas as milk producers. Table 1. Nutrient composition of lucerne hay and desert grass. Diet DM (%) OM (%) CP (%) Ash (%) Energy Kcal/ gm DM Lucerne Hay 83 78.5 18.7 24.5 4.72 Desert Grass 94 85.4 3.4 8.7 4.12 30 Elhadi 31 Effect of diet quality and housing on water status in Sudanese desert sheep and goats Fluids Volume The findings of these measurements are given in Tables 3 and 4. TBW % was 72.6±1.4 and 75.8±3 in sheep and goat, respectively. These values are slightly higher than the values reported by MacFarlane et al. (1972) for these ruminants in the Somali desert, using similar procedures. The relatively high value might be due to the 12-hours post injection samples; at this time of sampling, some losses of the isotope could have occurred, which may have resulted in the overestimation of TBW. Since equilibrium of 3H could take 5-7 hours in this species, such losses were presumably greater in the goats, however, the difference between the two species was not significant. TBW % reported by Kamal et al. (1972) for Ossami rams and Nubian bucks were higher than our values. This difference might indicate a better adaptive performance of our ruminants. The WTO (ml/ kg 0.82 / day) was 100±11.1 and 181±18.4 in the sheep and goats respectively as shown in Table 3. The goats turned over significantly more water than the sheep (P<0.01) and this was also reflected in the direct water intake. The difference in WTO rate might be due to the high degree of hyperthermia which was severe Table 3. TBW, WTO, water intake in grazing animals (sheep and goats) and confined sheep having Lucerne or desert grass (mean ± S.E). Parameter Grazing Animals Confined Sheep Goats Sheep Lucerne hay Desert grass Wt (kg) 17.5 ± 1.2 33.3 ± 2.2 30.4 ± 1.9 28.8 ± 1.5 TBW% 75.8 ± 3.0 72.6 ± 1.4 71.9 ± 1.9 68.7 ± 1.0 T1⁄2 (day) 5.2 ± 0.5 9.9 ± 0.8 5.0 ± 0.2 7.1 ± 0.1 Water intake ml/kg of B.Wt. or DM consumed/day 100 ± 9.8 49 ± 4.3 76.0 ± 1.1 57 ± 1.2 WTO/kg of B.Wt. or DM consumed/day 108 ± 9.6 53.0 ± 15.6 100 ± 2.5 66.0 ± 3.8 WTO/ 0.82 kg/day 181 ± 18.4 100 ± 11.1 183 ± 4.2 120 ± 6.4 Table 2. Rectal temperature of grazing sheep and goats and confined sheep having Lucerne and desert grass (mean ± S.E). Time of Day Rectal Temperature (°C) Grazing animals Confined sheep Goats Sheep Lucerne hay Desert grass 06:00 37.1 ± 0.1 37.9 ± 0.3 37.3 ± 0.2 37.1 ± 0.2 13:00 40.5 ± 0.1 40.3 ± 0.2 38.6 ± 0.1 38.4 ± 0.2 17:00 39.6 ± 0.2 39.8 ± 0.2 38.1 ± 0.1 37.9 ± 0.1 Table 4. Body weight (kg) and total body water (TBW) and its distribution in the body of grazing sheep and goats and in confined sheep having Lucerne day and desert grass (mean ± S.E). Parameter Grazing Animals Confined Sheep Goats Sheep Lucerne hay Desert grass Wt (kg) 17.5 ± 1.2 33.3 ± 2.2 30.4 ± 1.9 28.8 ± 1.5 TBW (%) 75.8 ± 3.0 72.6 ± 1.4 71.9 ± 1.9 68.7 ± 1.0 ECV1 (%) (SCN Space) 31.2 ± 0.8 28.1 ± 1.8 22.6 ± 1.1 26.2 ± 3.4 PV2 (%) 5.1 ± 0.2 5.0 ± 0.3 5.6 ± 0.4 4.7 ± 0.6 ISV3 (%) 26.1 ± 0.9 23.6 ± 1.8 17.0 ± 1.2 21.5 ± 2.8 ICV4* (%) 44.6 ± 2.5 44.5 ± 1.6 49.7 ± 3.3 41.7 ± 4.0 1Extracellular volume. 2Plasma volume (T-1824 space). 3Interstitial volume. 4*Intracellular volume. Rumen and digestive fluids are included in this space. 32 Elhadi in the goats and is reflected in the high extracellular space in the goats (31.2± 02) compared to (28.1±1.8) in the sheep. This is probably the result of more evaporative cooling in the goats, associated with high water turnover. Degen (1977), produced similar values for ECV % (28.6±1.09) in the grazing Awassi sheep at 32oC. Both species maintained similar plasma volume (PV) of 5% and intracellular volume (ICV) of 44 %. (Table 4). Effect of Feed Type The Lucerne-fed group consumed all the feed offered, while the desert grass group used to leave some of the feed. Two sheep, in the Lucerne group, suffered mild diarrhoea during the first few days of the investigation, while none of the desert-grass group showed any signs of digestive disturbances. This indicates that sheep which are normally raised under extensive management and used to dry grass feeding needed only a short time to adapt to the new diet. The Lucerne group consumed 1 kg of food (0.83 kg DM / animal) and drank 2.2 liters of water, while the desert grass group consumed 0.7 kg of desert hay (0.66 kg DM / animal) and drank 1.6 liters of water. Both groups maintained their body weights over the period of two weeks, indicating that both diets satisfied their maintenance requirements, since the desert grass is of low nitrogen content (Table 1), it seems that these desert sheep retained more nitrogen in their bodies with a reduced amount of water intake compared to the high water consumption with the Lucerne diet. Table 3, indicates that both groups had similar 3H space TBW. However, the Lucerne group had significantly (P<0.01) higher WTO associated with higher intake, probably indicating higher nitrogen excretion by the kidneys. Previous reports indicated that water restriction improved the nitrogen retention in sheep (English, 1966; Topps and Elliot, 1967; Singh, More and Sahani 1976). It is more probable that the adaptive feature of the desert sheep is that more nitrogen is retained with reduced water intake. The distribution of the 3H space (TBW) is shown in Table 4, the striking feature in these results is that the extracellular space is higher in the animals eating a poor diet (26.2±3.4) compared to those on a rich diet (Lucerne) (22.6±1.1). These findings are in agreement with that of MacFarlane et al (1959), who found high values in sheep with poor nutrition. Since these two groups of animals did not show a wide diurnal variation in their body temperature (Table 2), as did grazing sheep (Experiment 1), their ECV% is lower than that of the grazing sheep (Table 4). Both diet-groups had a similar plasma volume (PV). However, the intracellular volume (ICV) of the Lucerne group was 49.7% while that of grazing sheep was 44.5% (Table 4) which might indicate a large rumen space in the Lucerne group which consumed more feed in comparison to sheep having a poor diet; ICV% is 41.7 (Table 4). References Degen, A.A. 1977. Fat-tailed Awassi and German Merino sheep under semi-arid conditions. 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Phillipson (Editor), 362-374. England. Oriel Press. Macfarlane, W.V., B. Howard and G. M. O. Maloiy. 1972. Tritiated water in field studies of ruminants in Africa. In: Proceedings of Isotopes Studies on Physiology of Domestic Animals. p 83, STI / PUB / 309. IAEA. Vienna. Singh, N.B., T. More and K.L. Sahni. 1976. The effect of water deprivation on food intake, nutrient digestibility and nitrogen retention in sheep. Journal of Agricultural Science, Cambridge, 86:431-433. Topps, J. H. and R. C. Elliot. 1967. Partition of nitrogen in uterine of African sheep given a variety of low protein diet. Animal Production 9:219-227.