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Effects of water deprivation on feed utilization and mineral balances in sheep drinking natural saline well water
Journalof Arid Environments (1989) 16, 323-329
Effects of water deprivation on feed utilization and mineral balances in sheep drinking natural saline well water M. H. Ahrned,* M. F. A. Farid,* Safinaz M. Shawket* & N. I. Hassan* Accepted 11 May 1988 The present trials dealt with the combined effectof water salinityand infrequent water intake, onceevery72 hours, in two groups of rams fed roughagediets at the maintenance levelof digested protein intake, compared with sheep offered fresh tap water daily as controls. The results indicated that daily watered sheep responded favourably to drinking saline well water in terms of performance and weight gain, as well as nitrogen and mineral balances. Intermittent saline water intake, on the other hand, seemed to affect all characteristics studied adversely. The animals lost weight, digestive capacity was reduced and, therefore, DOM and DCP intakes decreasedsignificantly. Nitrogen and sodium balancesbecame negative, and the other mineral balances were also adversely affected. Further experiments are needed, particularly to re-evaluate established tolerance levels (I' 3% NaCI) which may differ according to types of salts in the well water and also under conditions of long adaptation to water deprivation.
Introduction Grazing sheep inhabiting arid and semi-arid rangelands, such as those in the northwestern coastal zone of Egypt, are usually dependent on drinking well water with varying degrees of salinity, commonly increasing during the dry season. Most investigators have experimented with waters containing varying concentrations of sodium chloride with or without other salts. Peirce (1966, 1968) conducted experiments utilizing synthetic water prepared after the analysis of natural saline well water commonly found in the Australian rangelands. Ahmed (1984) and Ahmed et al. (1985) experimented with natural saline well water in Egypt containing on average 9110 ppm total salinity. They reported improved performance and weight gain, efficiency of feed utilization and mineral balances. However, it appeared to affect the rumen function adversely but not the overall apparent digestion of feed. Furthermore, intermittent watering and water deprivation for up to 3-4 days is also a common practice under these semi-arid conditions. Water deprivation was frequently reported beneficial in terms offeed and nitrogen utilization and water conservation (e.g. More & Sahni, 1978; Farid et al., 1979; Farid & Abdel-Aziz, 1984). It was, therefore, of interest to investigate possible interactions between water salinity and water deprivation on feed utilization and mineral balances in sheep drinking natural saline well water.
* Desert Research Institute, Al-Matareya, Cairo, Egypt. 0140-1963/89/030323+07 $03.00/0
© 1989 Academic Press Limited
324
M. H. AHMED ET AL.
Materials and methods
Animals and management Eight 3-year-old Barki X Merino crossbred rams, 62 kg average live weight, were used in the study which lasted 8 weeks. The rams were fed berseem, Trifolium alexandrinum, hay to satisfy only maintenance requirements for digestible crude protein (A.R.C., 1965). Barley straw was allowed ad lib. The hay and straw contained 89'1 and 88·5% organic matter (OM) and 14'6 and 4·8% crude protein (CP), respectively, on dry matter basis. Feeds were offered twice daily at 0900 and 1800 h. Refusals were weighed each morning and intake was recorded. Water was made available to the animals for one hour daily or once every 3 days at morning feeding time. Fasted live weights were recorded weekly for the duration of the experiment.
Treatments The animals were divided randomly into two groups, four animals each. One group was offered saline well water daily, while the second group was intermittently offered the saline water once every 72 hours. One animal from the first group was excluded for reasons not apparently related to treatments. The saline water was obtained from two traditional shallow wells in the Maryot area, about 35 km south-west of Alexandria. Total salinity varied between 8900 and 9235 ppm. The hydrogen ion concentration (pH) and total and specific salinity of fresh and saline waters are presented in Table 1. Analyses were carried out on composite samples collected daily during the one-week collection period. In addition, data from a comparable treatment where four rams were similarly fed and watered daily fresh tap water (Ahmed, 1984) were included for comparison, i.e. a control group.
Experimental procedures The experiment lasted for 7 weeks (preliminary period) with a further week for collection. During the last week of the preliminary period the rams were placed in metabolism cages for adaptation. They were equipped with faecal collection bags attached to a harness fitted to the animal. Urine was allowed to drain into collection bottles containing 10 ml sulphuric acid diluted to half strength. The digestion and balance experiments were carried out during the eighth week in the conventional manner. Table 1. Mineral content offresh andsaline wellwater, ppm 1 Attributes
pH Total salinity, ppm Sodium Potassium Calcium Zinc Manganese Copper
Fresh tap water 7-6
600 162 30
94
20 13 12
Saline well water 9'3
9110 2420 1850
1730
90 14 25
I Mineral analyses were carriedout on composite samples collected dailyduring the one weekcollection period, the eighth week of the experimental period.
325
EFFECTS OF WATER DEPRIV AnON ON SHEEP
Proximate constituents of feeds, feed refusals and faeces were carried out according to officialprocedures (A.O.A.C., 1970). The micro-KjeldahlmethodofChibnalletal. (1943) was used for the determination of total urinary nitrogen. Minerals and the trace elements were determined by atomic absorption procedures after acid digestion of the samples. Statistical analyses were carried out by the Duncan's multiple range test for the significance of differences between treatment means as described by Steel & Torrie (1960). Results
Intake and nutrient digestibilities Results summarized in Table 2 indicate that drinking the saline water increased salt intake by about 0·2 g/day/kg (fresh vs. saline water daily). Also, free water intake per unit dry matter consumed increased 39'6% (p < 0.05), from 3' 38 to 4'72 ml/g OM intake, but feed intake decreased 8'1 % (p < 0.05), from 18·02 to 16'56 g/day/kg. On the other hand, water deprivation decreased total salt intake even below the intake recorded for those rams drinking fresh water daily, 1·92 vs. 2' 28 g/day/kg, respectively. This had resulted from the significant decrease in both feed intake (-15'2%) and free water intake (-33'7%) as compared to those drinking the saline water daily. Although drinking the saline water daily had not affected apparent digestibilities nor the digested nutrients intake, water deprivation resulted in a distinct decrease in the digestion of dry matter (OM), organic matter (OM) and crude protein (CP), which was reflected in a significant (p < 0'05) reduction in digested OM and digested CP intakes (Table 2). These transactions were directly reflected upon animal performance expressed in terms of weight changes, g/day, as the results clearly indicate that drinking the saline well water daily was Table 2. Weight changes, feed and water intakes and apparent digestibilities in sheep drinkingfresh or salinewaterl Fresh water daily
Saline water daily
Saline water intermittent
4 65·5 ± 6'97 -29'2 ± 68'S" 18·02 ± 1·22a
3 63·4 ± 2·22 +3'3 ± 72'l a 16·56 ± 0'95 b
4 59'1 ± 4·08 -29'3 ± 80·9a 14'04 ± 2'54 c
Free water intake: mUd/kg ml/g DM intake
59'8 ± lO'7b 3-38 ± 0'64 b
79·9 ± 9·90a 4'72 ± 0'39 a
44'0 ± 6·09c 3'13 ± 0'28 c
Total salt intake: g/d/kg from diet, % from water, %
2'28 ± 0'36 98'7 Jo3
2'49 ± 0'17 81'4 18'6
1'92±0'31 86'2 13-8
Apparent digestion, % dry matter organic matter crude protein
60·3 ± 1'43 62-6 ± 1'75 59·0 ± 2·06
61·2 ± Jo33 63·0 ± 0·98 61-3 ± 1·91
56·2 ± 1'10 60'1 ± 0'67 55·8 ± 3'61
10·58 ± l'83 a 1'13 ± o-ro-
9'68 ± 0'66 a 1'09 ± 0'05'
7'92 ± 1.19b 0'93 ± o.io-
Attributes Number of animals Initial weight, kg Weight change, g/day Dry matter intake, g/dlkg
Digested nutrients intake: DOMg/dlkg DCP, g/dlkg
1 Values are means ± S.D. Means in a row with different superscripts were significantly (p < 0'05) different according to Duncan's multiple range test (Steel & Torrie, 1960).
M. H. AHMED ET AL.
326
Table 3. Parameters of nitrogen utilization in sheep drinking fresh orsaline water l
Attributes Nitrogendata, g/day intake faecal digested urinary balance Digested-N retained, %
Fresh water daily 20·08 ± 2·83' 8·24±0·96' 11·84 ± 1'00' 11·19 ± 1·31' + 0'65 ± 1·92' 5'75 ± 19'85
Saline water daily
Saline water intermittent
18·08 ± 0'81 b 7·00±0·57' 11·08 ± 0'45' 9·80 ± 0'44' +1'28 ± 0·88' 11-65 ± 8'95
14·83 ± 1·69< 6·59±1·13' 8' 24 ± 0'83 b 10·75 ± 1·31' -2,51 ± 0'62 b -30'45 ± 6·50
I Values are means ± S.D. Means in a rowwith differentsuperscripts were significantly (p < 0'05) differentaccording to Duncan's multiple range test (Steel & Torrie, 1960).
beneficial to the animal, whereas the combined effect of water salinity and water deprivation adversely affected weight gain and feed and nitrogen utilization.
Nitrogen balance In line with the above mentioned results, daily drinking the saline well water improved the nitrogen status of the animals even though nitrogen intake significantly (p < 0'05) decreased about 10%(Table 3). In this regard, nitrogen balance improved, l- 28 vs. 0·65 g/ day, as well as the retention of digested nitrogen, 11·65 vs. 5'75%. Here again, it was also surprising to note the significant adverse effects of water deprivation where nitrogen intake significantly (p < 0'05) decreased from 18·08 to 14·83 g/day, but urinary nitrogen excretion was excessive and it was even greater than in their daily watered mates, 10'75 vs. 9'80 glday, respectively. Therefore, rams given saline well water and watered intermittently once every 72 hours lost substantial amounts of nitrogen, 2·51 glday, and this was in line with the observed loss of body weight observed earlier (Table 2).
Mineral balances Tables 4 and 5 summarize data on macro- and micro-element balances in all three experimental groups. It was observed that drinking the saline water daily increased the intake of all elements except manganese the concentration of which in saline water did not differ from that in fresh water. Percentage increase in total intake were 363, 42 and 33 per cent for sodium, potassium and calcium, respectively, and 290,5 and 66 per cent for zinc, manganese and copper, respectively. Water deprivation, on the other hand, decreased the intake of all six elements studied as a result of its effect on decreasing both feed and water intakes. In the case of manganese and copper, total intake dropped to values even lower than that of sheep drinking the fresh water. Drinking the saline water daily increased both faecal and urinary excretion of all elements in response to increased intake. However, water deprivation decreased excretion also in response to its effect on decreasing intake. Faeces was the main pathway for the excretion of calcium and all three trace-elements, zinc, manganese and copper. On the other hand, sodium and potassium were excreted almost exclusively through the urine. These findings were not different from those of Potter (1963), Weeth & Lesperance (1965) and Tomas et al. (1973).
327
EFFECTS OF WATER DEPRIVATION ON SHEEP
Table 4. The effects of water salinity and water deprivation on intake, excretion and apparent retention ofsodium, potassium and calcium, gldayl
Attributes Sodium Intake Excretion Balance Potassium Intake Excretion Balance Calcium Intake Excretion Balance 1
diet water total faeces urine total
diet water total faeces urine total
diet water total faeces urine total
Fresh water daily
Saline water daily
Saline water intermittent
1-42 0·53 1'95 ± 0'49 0·54 1'09 1'63 0'36±0'18
1'2! 7·81 9·02 ± 1·52
0·88 4'14 5·02 ± 0·80
± 1·54
0'76 5'14 5'90 -0'88 ± 0·91
12'46 0·01 IN7 ± 0'32 1·23 6'66 7-89
11'72 5·94 17'68 ± 1'57 1·47 8'95 10·42
9'84 3'16 13·00 ± 1'74 1'41 7'35 8.76
4'58 ± 0'67
7'62 ± 1'79
4'24 ± 0'95
12'47 0·31 12·78 ± 0·92 6·91 }'28 8'19 4·59±1·29
11·45 5·58 17·03 ± 1-61 12-39 1·53 13-92 8'11 ± 2·11
9·91 3'05 12'96 ± 1'41 10'22 1'20 11·42
0'84 5·55 6'39 2·63
1·54 ± 0'72
Values are means (g1day) ± S.D.
Changes in intake and excretion were reflected upon observed values for apparent retention of all six elements (Tables 4 and 5). Apparent retentions were always positive even when the animals were drinking the fresh water. Drinking the saline water daily promoted better retention of all elements. The effect was particularly great for sodium, but was less noticeable for calcium and manganese, the others being intermediate. However, giving the saline water intermittently adversely affected the apparent retention of all six elements studied, and in particular that of sodium, calcium and manganese. Indeed, water-deprived animals exhibited a net loss of sodium (0'88 g/day) even though their intake was 2·57 times as much as that of animals offered fresh water daily and were practically in sodium equilibrium (+0'36 g/day).
Discussion Saline well water had an average total salinity of9110 ppm as compared to 600 ppm in fresh tap water. These levels were below tolerance levels frequently reported for sheep drinking sodium chloride solutions, i.e. 13,000 ppm (Squires, 1973). Tap water was slightly alkaline whereas saline well water was strongly alkaline, pH 7'6 vs. 9'3, respectively. The well water was particularly rich in sodium, potassium, calcium, zinc and copper. The present results concerning the observed favourable effects of saline well water
M. H. AHMED ET AL.
328
Table 5. The effects of water salinity and water deprivation on intake,
excretion and apparent retention of zinc, manganese and copper, mgfdayl Fresh water daily
Saline water daily
Saline water intermittent
diet water total
23 57 80±1O'1
21 291 312 ± 54·6
17 154 171 ± 26·5
faeces urine total
14 9 23
142 26 169
69 33 102
57 ± 9·3
144± 16·1
69 ± 12·1
diet water total
47 38 58 ± 8·0
44 45 89 ± 11·0
35 24 59 ± 10·1
faeces urine total
46 3 49
47 3 50
42 3 45
36 ± 7-6
39 ± 5·5
14 ± 5'1
20 39 59 ± 18·4 16 4 20
17 81 98 ± 16·4
7 21 28 ± 9·0
26 3 29
11 3 14
39 ± 11'4
69 ± 10'1
44 ± 9·5
Attributes Zinc Intake
Excretion
Balance Manganese Intake
Excretion
Balance Copper Intake
Excretion
Balance I
diet water total faeces urine total
Values are means (mglday) ± S.D.
offered on a daily basis appear to be in line with previous investigations. Peirce (1966, 1968), Tomas et al. (1973), Hemsley et al, (1975), Singh & Taneja (1979), Ahmed et al. (1985) and others observed either nil or positive effects on weight gain and/or reproductive performance. On the other hand, the observed adverse effects of intermittently watering sheep with saline well water on all feed intake, apparent digestibilities, nitrogen and mineral balances and live weight changes contradicted the frequently reported benefits of water deprivation observed in animals offered fresh water especially when fed roughage diets with low protein content (e.g. French, 1956a,b; Payne, 1963; More & Sahni, 1978; Farid et al., 1979; Ummana et al., 1981; Farid & Abdel-Aziz, 1984). In conclusion, it is indicated that daily watered sheep responded favourably to drinking natural saline well water which was alkaline (pH 9'3) but its total salinity was below accepted tolerance level, 9110 vs. 13,000 ppm. Improved weight gain and the efficiencyof feed utilization were clearly evident even though feed intake slightly decreased and digestibilities were not apparently affected. Under the present experimental conditions animals appeared to benefit from drinking the natural saline well water even though the general belief had been that water salinity may be to the disadvantage of the animal. However, in view of the negative results obtained from the combined effects of water salinity and water deprivation, a situation not uncommon under natural grazing conditions during the dry season in arid and semi-arid range-lands, a definite conclusion cannot be drawn before further experiments are carried out. These are to concentrate, in particular, on what may possibly be a modifying effect of water deprivation on tolerance
EFFECTS OF WATER DEPRIVATION ON SHEEP
329
levels, especially under field conditions which may also differ according to type of salts in the well water. Further studies may also include mineral supply from the pasture plants, mineral availabilities and interactions and possible long-term effects on organ functions especially the kidneys.
References Ahmed, M. H. (1984). Studies on nitrogen metabolism in ruminants: Effects of drinking saline water on nitrogen metabolism and rumen and kidney functions in sheep. Ph.D. Thesis, University of Alexandria, Egypt. Ahmed, M. H., Farid, M. F. A., Hassan, N. I., Borhami, B. E. & Shawket, M. (1985). Effects of drinking saline well water in sheep. I. Feed and nitrogen utilization and mineral balances. 1st International Congress on Animal Production in Arid Zones, 7-14 September, 1985, Damascus, Syria. A.O.A.C. (1970). Official Methods of Ana{ysis. Association of Official Agricultural Chemists, Washington D.C. A.R.C. (1965). The NutrientRequirements of Farm Livestock. 2. Ruminants. Agricultural Research Council, London. Chibnall, A. C., Reese, M. W. & Williams, E. F. (1943). The total nitrogen content of egg albumen and other proteins. BiochemicalJournal, 37: 354. Farid, M. F. A. & Abdel-Aziz, D. M. (1984). Effect of intermittent water intake on feed utilization in sheep given urea supplements in the drinking water. World Review of Animal Production, 20(4): 21-30. Farid, M. F. A., Shawket, S. M. & Abdel-Rahman, M. H. A. (1979). Observations on the nutrition of camels and sheep under stress. Workshop onCamels, Khartoum, Sudan. International Foundation of Science (IFS), Sweden, Provisional Report, 6: 125-170. French, M. H. (1956a). The effect of infrequent water intake on the consumption and digestibility of hay by Zebu cattle. EmpireJournal of Experimental Agriculture, 24: 128-136. French, M. H. (1956b). The importance of water in the management of cattle. East African AgriculturalJournal, 21: 171-181. Hemsley, J. A., Hogan, J. P. & Weston, R. H. (1975). Effect of high intake of sodium chloride on the utilization of a protein concentrate by sheep. II. Digestion and absorption of organic matter and electrolytes. Australian Journal of Agricultural Research, 26: 715-725. More, T. & Sahni, K. L. (1978). Effect of long-term water deprivation on body weight and water intake of breeding ewes under semi-arid conditions. Journal of Agricultural Science, Cambridge, 90: 435-439. Payne, W. J. A. (1963). Specific problems of semi-arid areas. Proceedings, 6th International Congress of Nutrition, Edinburgh, 213-227. Peirce, A. W. (1966). Studies on salt tolerance of sheep. VI. The tolerance of wethers in pens for drinking waters of the types obtained from underground sources in Australia. AustralianJournal of Agricultural Research, 17: 209-218. Peirce, A. W. (1968). Studies on salt tolerance of sheep. VII. The tolerance of ewes and theirlambs in pens for drinking water of the types obtained from underground sources in Australia. Australian Journal of Agricultural Research, 19: 577-587. Potter, B. J. (1963). The effect of saline water on kidney tubular function and electrolyte excretion in sheep. Australian Journal of Agricultural Research, 14: 518. Singh, N. & Taneja, G. C. (1979). Effect of prolonged salt intake on the production of ewes and weight of lambs born to Marwari sheep. IndianJournal of Animal Science, 13: 71-74. Squires, V. R. (1973). A review of Australian experience with saline drinking water for sheep. Proceedings, Water-Animal Relations Symposium, Kimberly, Idaho. p. 133. Steel, R. G. D. & Torrie, J. R. (1960). Principles and Procedures of Statistics. New York: McGrawHill. Tomas, F. M., Jones, G. B., Potter, B. J. & Langsford, G. L. (1973). Influence of saline drinking water on mineral balances in sheep. Australian Journal of Agricultural Research, 24: 377-386. Ummana, N. N., Chinemi, C. N., Saror, D. I., Ahmed, A. & Abed, S., (1981). Response of Yankasa sheep to various lengths of water deprivation. Journal of Agricultural Science, Cambridge, 98: 343-346. Weeth, H. J. & Lesperance, A. L. (1965). Renal function of cattle under various water and salt loads. Journal of Animal Science, 24: 441-447.
Effects of water deprivation on feed utilization and mineral balances in sheep drinking natural saline well water M. H. Ahrned,* M. F. A. Farid,* Safinaz M. Shawket* & N. I. Hassan* Accepted 11 May 1988 The present trials dealt with the combined effectof water salinityand infrequent water intake, onceevery72 hours, in two groups of rams fed roughagediets at the maintenance levelof digested protein intake, compared with sheep offered fresh tap water daily as controls. The results indicated that daily watered sheep responded favourably to drinking saline well water in terms of performance and weight gain, as well as nitrogen and mineral balances. Intermittent saline water intake, on the other hand, seemed to affect all characteristics studied adversely. The animals lost weight, digestive capacity was reduced and, therefore, DOM and DCP intakes decreasedsignificantly. Nitrogen and sodium balancesbecame negative, and the other mineral balances were also adversely affected. Further experiments are needed, particularly to re-evaluate established tolerance levels (I' 3% NaCI) which may differ according to types of salts in the well water and also under conditions of long adaptation to water deprivation.
Introduction Grazing sheep inhabiting arid and semi-arid rangelands, such as those in the northwestern coastal zone of Egypt, are usually dependent on drinking well water with varying degrees of salinity, commonly increasing during the dry season. Most investigators have experimented with waters containing varying concentrations of sodium chloride with or without other salts. Peirce (1966, 1968) conducted experiments utilizing synthetic water prepared after the analysis of natural saline well water commonly found in the Australian rangelands. Ahmed (1984) and Ahmed et al. (1985) experimented with natural saline well water in Egypt containing on average 9110 ppm total salinity. They reported improved performance and weight gain, efficiency of feed utilization and mineral balances. However, it appeared to affect the rumen function adversely but not the overall apparent digestion of feed. Furthermore, intermittent watering and water deprivation for up to 3-4 days is also a common practice under these semi-arid conditions. Water deprivation was frequently reported beneficial in terms offeed and nitrogen utilization and water conservation (e.g. More & Sahni, 1978; Farid et al., 1979; Farid & Abdel-Aziz, 1984). It was, therefore, of interest to investigate possible interactions between water salinity and water deprivation on feed utilization and mineral balances in sheep drinking natural saline well water.
* Desert Research Institute, Al-Matareya, Cairo, Egypt. 0140-1963/89/030323+07 $03.00/0
© 1989 Academic Press Limited
324
M. H. AHMED ET AL.
Materials and methods
Animals and management Eight 3-year-old Barki X Merino crossbred rams, 62 kg average live weight, were used in the study which lasted 8 weeks. The rams were fed berseem, Trifolium alexandrinum, hay to satisfy only maintenance requirements for digestible crude protein (A.R.C., 1965). Barley straw was allowed ad lib. The hay and straw contained 89'1 and 88·5% organic matter (OM) and 14'6 and 4·8% crude protein (CP), respectively, on dry matter basis. Feeds were offered twice daily at 0900 and 1800 h. Refusals were weighed each morning and intake was recorded. Water was made available to the animals for one hour daily or once every 3 days at morning feeding time. Fasted live weights were recorded weekly for the duration of the experiment.
Treatments The animals were divided randomly into two groups, four animals each. One group was offered saline well water daily, while the second group was intermittently offered the saline water once every 72 hours. One animal from the first group was excluded for reasons not apparently related to treatments. The saline water was obtained from two traditional shallow wells in the Maryot area, about 35 km south-west of Alexandria. Total salinity varied between 8900 and 9235 ppm. The hydrogen ion concentration (pH) and total and specific salinity of fresh and saline waters are presented in Table 1. Analyses were carried out on composite samples collected daily during the one-week collection period. In addition, data from a comparable treatment where four rams were similarly fed and watered daily fresh tap water (Ahmed, 1984) were included for comparison, i.e. a control group.
Experimental procedures The experiment lasted for 7 weeks (preliminary period) with a further week for collection. During the last week of the preliminary period the rams were placed in metabolism cages for adaptation. They were equipped with faecal collection bags attached to a harness fitted to the animal. Urine was allowed to drain into collection bottles containing 10 ml sulphuric acid diluted to half strength. The digestion and balance experiments were carried out during the eighth week in the conventional manner. Table 1. Mineral content offresh andsaline wellwater, ppm 1 Attributes
pH Total salinity, ppm Sodium Potassium Calcium Zinc Manganese Copper
Fresh tap water 7-6
600 162 30
94
20 13 12
Saline well water 9'3
9110 2420 1850
1730
90 14 25
I Mineral analyses were carriedout on composite samples collected dailyduring the one weekcollection period, the eighth week of the experimental period.
325
EFFECTS OF WATER DEPRIV AnON ON SHEEP
Proximate constituents of feeds, feed refusals and faeces were carried out according to officialprocedures (A.O.A.C., 1970). The micro-KjeldahlmethodofChibnalletal. (1943) was used for the determination of total urinary nitrogen. Minerals and the trace elements were determined by atomic absorption procedures after acid digestion of the samples. Statistical analyses were carried out by the Duncan's multiple range test for the significance of differences between treatment means as described by Steel & Torrie (1960). Results
Intake and nutrient digestibilities Results summarized in Table 2 indicate that drinking the saline water increased salt intake by about 0·2 g/day/kg (fresh vs. saline water daily). Also, free water intake per unit dry matter consumed increased 39'6% (p < 0.05), from 3' 38 to 4'72 ml/g OM intake, but feed intake decreased 8'1 % (p < 0.05), from 18·02 to 16'56 g/day/kg. On the other hand, water deprivation decreased total salt intake even below the intake recorded for those rams drinking fresh water daily, 1·92 vs. 2' 28 g/day/kg, respectively. This had resulted from the significant decrease in both feed intake (-15'2%) and free water intake (-33'7%) as compared to those drinking the saline water daily. Although drinking the saline water daily had not affected apparent digestibilities nor the digested nutrients intake, water deprivation resulted in a distinct decrease in the digestion of dry matter (OM), organic matter (OM) and crude protein (CP), which was reflected in a significant (p < 0'05) reduction in digested OM and digested CP intakes (Table 2). These transactions were directly reflected upon animal performance expressed in terms of weight changes, g/day, as the results clearly indicate that drinking the saline well water daily was Table 2. Weight changes, feed and water intakes and apparent digestibilities in sheep drinkingfresh or salinewaterl Fresh water daily
Saline water daily
Saline water intermittent
4 65·5 ± 6'97 -29'2 ± 68'S" 18·02 ± 1·22a
3 63·4 ± 2·22 +3'3 ± 72'l a 16·56 ± 0'95 b
4 59'1 ± 4·08 -29'3 ± 80·9a 14'04 ± 2'54 c
Free water intake: mUd/kg ml/g DM intake
59'8 ± lO'7b 3-38 ± 0'64 b
79·9 ± 9·90a 4'72 ± 0'39 a
44'0 ± 6·09c 3'13 ± 0'28 c
Total salt intake: g/d/kg from diet, % from water, %
2'28 ± 0'36 98'7 Jo3
2'49 ± 0'17 81'4 18'6
1'92±0'31 86'2 13-8
Apparent digestion, % dry matter organic matter crude protein
60·3 ± 1'43 62-6 ± 1'75 59·0 ± 2·06
61·2 ± Jo33 63·0 ± 0·98 61-3 ± 1·91
56·2 ± 1'10 60'1 ± 0'67 55·8 ± 3'61
10·58 ± l'83 a 1'13 ± o-ro-
9'68 ± 0'66 a 1'09 ± 0'05'
7'92 ± 1.19b 0'93 ± o.io-
Attributes Number of animals Initial weight, kg Weight change, g/day Dry matter intake, g/dlkg
Digested nutrients intake: DOMg/dlkg DCP, g/dlkg
1 Values are means ± S.D. Means in a row with different superscripts were significantly (p < 0'05) different according to Duncan's multiple range test (Steel & Torrie, 1960).
M. H. AHMED ET AL.
326
Table 3. Parameters of nitrogen utilization in sheep drinking fresh orsaline water l
Attributes Nitrogendata, g/day intake faecal digested urinary balance Digested-N retained, %
Fresh water daily 20·08 ± 2·83' 8·24±0·96' 11·84 ± 1'00' 11·19 ± 1·31' + 0'65 ± 1·92' 5'75 ± 19'85
Saline water daily
Saline water intermittent
18·08 ± 0'81 b 7·00±0·57' 11·08 ± 0'45' 9·80 ± 0'44' +1'28 ± 0·88' 11-65 ± 8'95
14·83 ± 1·69< 6·59±1·13' 8' 24 ± 0'83 b 10·75 ± 1·31' -2,51 ± 0'62 b -30'45 ± 6·50
I Values are means ± S.D. Means in a rowwith differentsuperscripts were significantly (p < 0'05) differentaccording to Duncan's multiple range test (Steel & Torrie, 1960).
beneficial to the animal, whereas the combined effect of water salinity and water deprivation adversely affected weight gain and feed and nitrogen utilization.
Nitrogen balance In line with the above mentioned results, daily drinking the saline well water improved the nitrogen status of the animals even though nitrogen intake significantly (p < 0'05) decreased about 10%(Table 3). In this regard, nitrogen balance improved, l- 28 vs. 0·65 g/ day, as well as the retention of digested nitrogen, 11·65 vs. 5'75%. Here again, it was also surprising to note the significant adverse effects of water deprivation where nitrogen intake significantly (p < 0'05) decreased from 18·08 to 14·83 g/day, but urinary nitrogen excretion was excessive and it was even greater than in their daily watered mates, 10'75 vs. 9'80 glday, respectively. Therefore, rams given saline well water and watered intermittently once every 72 hours lost substantial amounts of nitrogen, 2·51 glday, and this was in line with the observed loss of body weight observed earlier (Table 2).
Mineral balances Tables 4 and 5 summarize data on macro- and micro-element balances in all three experimental groups. It was observed that drinking the saline water daily increased the intake of all elements except manganese the concentration of which in saline water did not differ from that in fresh water. Percentage increase in total intake were 363, 42 and 33 per cent for sodium, potassium and calcium, respectively, and 290,5 and 66 per cent for zinc, manganese and copper, respectively. Water deprivation, on the other hand, decreased the intake of all six elements studied as a result of its effect on decreasing both feed and water intakes. In the case of manganese and copper, total intake dropped to values even lower than that of sheep drinking the fresh water. Drinking the saline water daily increased both faecal and urinary excretion of all elements in response to increased intake. However, water deprivation decreased excretion also in response to its effect on decreasing intake. Faeces was the main pathway for the excretion of calcium and all three trace-elements, zinc, manganese and copper. On the other hand, sodium and potassium were excreted almost exclusively through the urine. These findings were not different from those of Potter (1963), Weeth & Lesperance (1965) and Tomas et al. (1973).
327
EFFECTS OF WATER DEPRIVATION ON SHEEP
Table 4. The effects of water salinity and water deprivation on intake, excretion and apparent retention ofsodium, potassium and calcium, gldayl
Attributes Sodium Intake Excretion Balance Potassium Intake Excretion Balance Calcium Intake Excretion Balance 1
diet water total faeces urine total
diet water total faeces urine total
diet water total faeces urine total
Fresh water daily
Saline water daily
Saline water intermittent
1-42 0·53 1'95 ± 0'49 0·54 1'09 1'63 0'36±0'18
1'2! 7·81 9·02 ± 1·52
0·88 4'14 5·02 ± 0·80
± 1·54
0'76 5'14 5'90 -0'88 ± 0·91
12'46 0·01 IN7 ± 0'32 1·23 6'66 7-89
11'72 5·94 17'68 ± 1'57 1·47 8'95 10·42
9'84 3'16 13·00 ± 1'74 1'41 7'35 8.76
4'58 ± 0'67
7'62 ± 1'79
4'24 ± 0'95
12'47 0·31 12·78 ± 0·92 6·91 }'28 8'19 4·59±1·29
11·45 5·58 17·03 ± 1-61 12-39 1·53 13-92 8'11 ± 2·11
9·91 3'05 12'96 ± 1'41 10'22 1'20 11·42
0'84 5·55 6'39 2·63
1·54 ± 0'72
Values are means (g1day) ± S.D.
Changes in intake and excretion were reflected upon observed values for apparent retention of all six elements (Tables 4 and 5). Apparent retentions were always positive even when the animals were drinking the fresh water. Drinking the saline water daily promoted better retention of all elements. The effect was particularly great for sodium, but was less noticeable for calcium and manganese, the others being intermediate. However, giving the saline water intermittently adversely affected the apparent retention of all six elements studied, and in particular that of sodium, calcium and manganese. Indeed, water-deprived animals exhibited a net loss of sodium (0'88 g/day) even though their intake was 2·57 times as much as that of animals offered fresh water daily and were practically in sodium equilibrium (+0'36 g/day).
Discussion Saline well water had an average total salinity of9110 ppm as compared to 600 ppm in fresh tap water. These levels were below tolerance levels frequently reported for sheep drinking sodium chloride solutions, i.e. 13,000 ppm (Squires, 1973). Tap water was slightly alkaline whereas saline well water was strongly alkaline, pH 7'6 vs. 9'3, respectively. The well water was particularly rich in sodium, potassium, calcium, zinc and copper. The present results concerning the observed favourable effects of saline well water
M. H. AHMED ET AL.
328
Table 5. The effects of water salinity and water deprivation on intake,
excretion and apparent retention of zinc, manganese and copper, mgfdayl Fresh water daily
Saline water daily
Saline water intermittent
diet water total
23 57 80±1O'1
21 291 312 ± 54·6
17 154 171 ± 26·5
faeces urine total
14 9 23
142 26 169
69 33 102
57 ± 9·3
144± 16·1
69 ± 12·1
diet water total
47 38 58 ± 8·0
44 45 89 ± 11·0
35 24 59 ± 10·1
faeces urine total
46 3 49
47 3 50
42 3 45
36 ± 7-6
39 ± 5·5
14 ± 5'1
20 39 59 ± 18·4 16 4 20
17 81 98 ± 16·4
7 21 28 ± 9·0
26 3 29
11 3 14
39 ± 11'4
69 ± 10'1
44 ± 9·5
Attributes Zinc Intake
Excretion
Balance Manganese Intake
Excretion
Balance Copper Intake
Excretion
Balance I
diet water total faeces urine total
Values are means (mglday) ± S.D.
offered on a daily basis appear to be in line with previous investigations. Peirce (1966, 1968), Tomas et al. (1973), Hemsley et al, (1975), Singh & Taneja (1979), Ahmed et al. (1985) and others observed either nil or positive effects on weight gain and/or reproductive performance. On the other hand, the observed adverse effects of intermittently watering sheep with saline well water on all feed intake, apparent digestibilities, nitrogen and mineral balances and live weight changes contradicted the frequently reported benefits of water deprivation observed in animals offered fresh water especially when fed roughage diets with low protein content (e.g. French, 1956a,b; Payne, 1963; More & Sahni, 1978; Farid et al., 1979; Ummana et al., 1981; Farid & Abdel-Aziz, 1984). In conclusion, it is indicated that daily watered sheep responded favourably to drinking natural saline well water which was alkaline (pH 9'3) but its total salinity was below accepted tolerance level, 9110 vs. 13,000 ppm. Improved weight gain and the efficiencyof feed utilization were clearly evident even though feed intake slightly decreased and digestibilities were not apparently affected. Under the present experimental conditions animals appeared to benefit from drinking the natural saline well water even though the general belief had been that water salinity may be to the disadvantage of the animal. However, in view of the negative results obtained from the combined effects of water salinity and water deprivation, a situation not uncommon under natural grazing conditions during the dry season in arid and semi-arid range-lands, a definite conclusion cannot be drawn before further experiments are carried out. These are to concentrate, in particular, on what may possibly be a modifying effect of water deprivation on tolerance
EFFECTS OF WATER DEPRIVATION ON SHEEP
329
levels, especially under field conditions which may also differ according to type of salts in the well water. Further studies may also include mineral supply from the pasture plants, mineral availabilities and interactions and possible long-term effects on organ functions especially the kidneys.
References Ahmed, M. H. (1984). Studies on nitrogen metabolism in ruminants: Effects of drinking saline water on nitrogen metabolism and rumen and kidney functions in sheep. Ph.D. Thesis, University of Alexandria, Egypt. Ahmed, M. H., Farid, M. F. A., Hassan, N. I., Borhami, B. E. & Shawket, M. (1985). Effects of drinking saline well water in sheep. I. Feed and nitrogen utilization and mineral balances. 1st International Congress on Animal Production in Arid Zones, 7-14 September, 1985, Damascus, Syria. A.O.A.C. (1970). Official Methods of Ana{ysis. Association of Official Agricultural Chemists, Washington D.C. A.R.C. (1965). The NutrientRequirements of Farm Livestock. 2. Ruminants. Agricultural Research Council, London. Chibnall, A. C., Reese, M. W. & Williams, E. F. (1943). The total nitrogen content of egg albumen and other proteins. BiochemicalJournal, 37: 354. Farid, M. F. A. & Abdel-Aziz, D. M. (1984). Effect of intermittent water intake on feed utilization in sheep given urea supplements in the drinking water. World Review of Animal Production, 20(4): 21-30. Farid, M. F. A., Shawket, S. M. & Abdel-Rahman, M. H. A. (1979). Observations on the nutrition of camels and sheep under stress. Workshop onCamels, Khartoum, Sudan. International Foundation of Science (IFS), Sweden, Provisional Report, 6: 125-170. French, M. H. (1956a). The effect of infrequent water intake on the consumption and digestibility of hay by Zebu cattle. EmpireJournal of Experimental Agriculture, 24: 128-136. French, M. H. (1956b). The importance of water in the management of cattle. East African AgriculturalJournal, 21: 171-181. Hemsley, J. A., Hogan, J. P. & Weston, R. H. (1975). Effect of high intake of sodium chloride on the utilization of a protein concentrate by sheep. II. Digestion and absorption of organic matter and electrolytes. Australian Journal of Agricultural Research, 26: 715-725. More, T. & Sahni, K. L. (1978). Effect of long-term water deprivation on body weight and water intake of breeding ewes under semi-arid conditions. Journal of Agricultural Science, Cambridge, 90: 435-439. Payne, W. J. A. (1963). Specific problems of semi-arid areas. Proceedings, 6th International Congress of Nutrition, Edinburgh, 213-227. Peirce, A. W. (1966). Studies on salt tolerance of sheep. VI. The tolerance of wethers in pens for drinking waters of the types obtained from underground sources in Australia. AustralianJournal of Agricultural Research, 17: 209-218. Peirce, A. W. (1968). Studies on salt tolerance of sheep. VII. The tolerance of ewes and theirlambs in pens for drinking water of the types obtained from underground sources in Australia. Australian Journal of Agricultural Research, 19: 577-587. Potter, B. J. (1963). The effect of saline water on kidney tubular function and electrolyte excretion in sheep. Australian Journal of Agricultural Research, 14: 518. Singh, N. & Taneja, G. C. (1979). Effect of prolonged salt intake on the production of ewes and weight of lambs born to Marwari sheep. IndianJournal of Animal Science, 13: 71-74. Squires, V. R. (1973). A review of Australian experience with saline drinking water for sheep. Proceedings, Water-Animal Relations Symposium, Kimberly, Idaho. p. 133. Steel, R. G. D. & Torrie, J. R. (1960). Principles and Procedures of Statistics. New York: McGrawHill. Tomas, F. M., Jones, G. B., Potter, B. J. & Langsford, G. L. (1973). Influence of saline drinking water on mineral balances in sheep. Australian Journal of Agricultural Research, 24: 377-386. Ummana, N. N., Chinemi, C. N., Saror, D. I., Ahmed, A. & Abed, S., (1981). Response of Yankasa sheep to various lengths of water deprivation. Journal of Agricultural Science, Cambridge, 98: 343-346. Weeth, H. J. & Lesperance, A. L. (1965). Renal function of cattle under various water and salt loads. Journal of Animal Science, 24: 441-447.