Water utilization by sheep and goats in northern Nigeria

Water balance
Species and breed differences in water metabolism
Effects of diet on water metabolism
Physiological changes in water metabolism
Effects of water deprivation
Bibliography

A. A. Aganga

The author's address is: Botswana Agricultural College, Private Bag 0027, Gaborone, Botswana.

Water is the simplest of all substances in feeds yet it is not the simplest to determine. It is a dietary essential. An animal's first response to a restriction of water intake is a restriction of voluntary feed intake. Water intake by animals is controlled by the capacity of the digestive system. The presence of adequate water in body tissues is an essential prerequisite for the normal maintenance of life, and water is a fundamental constituent of all living cells. The significance of water in ruminant livestock production was reviewed by Aganga et al. (1986), who pointed out that the body water of ruminant animals is not fresh water since it contains salts in solution, and the salts inside and outside the cells are different in character. In Nigeria, especially in the Guinean and Sahelian savannah zones where there is a long dry season (as long as eight months) each year, water is not available all year-round. Consequently, the animals have to adapt to little water at certain times of the year. This article attempts to explore the water requirements of sheep and goats and their utilization of water in the semi-arid, tropical climate of northern Nigeria.

Water balance

The water balance of Yankasa sheep and Maradi goats was studied. The results obtained indicated that Yankasa rams consumed more feed and water, and therefore gained more weight, than the Maradi bucks.

This finding agrees with the report of Gihad (1976), who noted that goats fed tropical natural grass hay had a lower intake of water than sheep. The Yankasa rams had significantly more faecal output (P<0.01) than the Maradi bucks. Water intake and water loss in urine and faeces were significantly higher in sheep (P<0.01) than in goats. The study showed that Maradi goats can tolerate heat stress better than Yankasa sheep. The Maradi goats drank less water and produced drier faeces than the Yankasa sheep, indicating a better water conservation mechanism. The percentage of faecal water ranged from 50 to 60 percent for Yankasa sheep and from 40 to 45 percent for Maradi goats. Yankasa sheep voided 501.1 ml of urine daily, while Maradi goats excreted 382.9 ml each day. This is in agreement with the report of Houpt (1977), who stated that if an excess of water is ingested, urinary volume will rise. Daily metabolic water intake of Yankasa sheep was 19.02 ml/kg^0.75, which was significantly higher (P<0.01) than that of Maradi goats (16.95 ml/kg^0.75) (Table 1). The metabolic water intake for the sheep was 8.46 percent of the total intake, while that of goats was 9.34 percent of the total water intake.

Of the total water intake of sheep, 72.27 percent was utilized for evaporative cooling, while for goats 69.95 percent was used for the same purpose. Environmental temperatures ranged from 21° to 39°C during the period of experimentation, and the minimum relative humidity was 13 percent with a maximum of 67 percent.

1 Water balance of Yankasa sheep and Maradi goats

Bilan hydrique des moutons Yankasa et des chèvres Maradi

Balance hídrico de los ovinos Yankasa y las cabras Maradi

	Species		SE1
	Sheep	Goats
Number of animals	4	4
Average live weight (kg)	25.56	20.16	0.25
Metabolic mass (kg0.73)	10.95	8.96	0.08
Water drunk (ml/kg0.73/day)	202.53	152.42	8.14
Water intake in food (ml/kg0.73/day)	3.17	2.75	0.03
Metabolic water (ml/kg0.73/day)	19.023	16.952	0.36
Water loss in faeces (ml/kg0.73/day)	16.083	9.322	0.84
Water loss in urine (ml/kg0.73/day)	45.60	42.0	2.07
Evaporated water loss (ml/kg0.73/day)	162.403	120.402	6.74
Average daily urine production (ml)	501.1	382.9	9.16
Daily water intake (ml)	2218.0	1364.0	68.79
Daily hay intake (g)	500.0	375.0
Average daily faecal output (g)	362.1	208.8	10.92

¹ Standard error.
^2,3 Means within the same variable bearing different superscript differ (P<0.01).

2 Whole body composition of sheep and goats

Composition corporelle des ovins et des caprins

Composición del cuerpo de ovinos y caprinos

	Uda sheep	Yankasa sheep	Sahel goats	Maradi goats	SE1
Live weight (kg)	30.5	29.5	12.6	16.3	1.16
Water (% live weight)2	68.9	62.2	71.2	56.6	3.66
Protein (% live weight)3	13.1	13.8	16.5	14.6	0.66
Ash (% live weight)	3.15	3.44	3.05	3.04	0.23
Fat (% live weight)2	15.5	20.8	6.8	21.8	3.43

¹ Standard error.
² Sahel vs. Maradi goat, significant at P<0.05.
³ Uda and Yankasa sheep vs. Sahel and Maradi goats, significant at P<0.05.
Source: Aganga et al., 1989.

Species and breed differences in water metabolism

Water intake differed significantly between sheep and goats (P<0.01), as well as among the various breeds. The total body water content of individual sheep ranged between 52.37 and 71.51 percent live weight, while values for goats were between 48.16 and 74.69 percent live weight (Table 2).

Total body water is the key component of living ruminants as it is in monogastric animals (Panaretto and Till, 1963). The tritiated water spaces (TWS) (kg) were related to total body water (kg), the correlational coefficient being 0.992 (Y = 0.353 + 0.841 x). TWS was least for Maradi goats (66.1 percent live weight), while the value for Sahel goats was 77.8 percent live weight. TWS values for Yankasa and Uda sheep were 73.6 and 80.5 percent live weight, respectively (Table 3). The biological half-life of tritium was least in Yankasa (116 h) and longest in Sahel (173 h). Water turnover rates per day per animal (litres) were 2.52, 2.63, 0.86 and 1.09 for Uda sheep, Yankasa sheep, Sahel goats and Maradi goats, respectively.

Macfarlane, Howard and Morris (1966) suggested that water turnover is linked with the use of water for metabolic processes and may be correlated with the synthesis of protein and energy. They further suggested that water turnover was related more to energy turnover than to heat dissipation in tropical animals. A lower water turnover rate in goats than in sheep suggests that under poor, dry conditions, goats are better adapted for survival than sheep. The fact that the water turnover rate of Sahel goats was the lowest suggests that under conditions where supplies of drinking-water are limited, they would be the more suitable breed for production.

Effects of diet on water metabolism

A series of experiments was conducted to study the effects of diet on water metabolism. The first trial tested the influence of different types of feed on water metabolism in sheep and goats. Results of this trial show a significant difference in water intake (P<0.01) between sheep and goats on the various diets (Table 4). In the study, water requirements varied with types of feed, indicating that an amount of water that was adequate at one time for a particular diet could be insufficient for another. Further trials tested the effect of feed restriction on water metabolism.

The studies showed that feed intake significantly affected the water intake of the animals (P<0.01). Findings pointed out the dependency of water intake on feed intake (dry matter basis). Feed management through variations in concentrate-to-roughage ratios as well as processing methods also significantly influenced water intake. Water intake of the animals varied with the ratio of concentrate to roughage in their diets (Table 5).

3 Tritiated water space, biological half-life of tritium and water turnover rate of sheep and goats

Pourcentage d'eau tritiée, demi-période biologique du tritium et taux de renouvellement de l'eau chez les ovins et les caprins

Espacio de agua tritiada, semivida biológica del tritio y tasa de renovación del agua en ovinos y caprinos

Breeds	Live weight (kg)	Tritiated water space (% live weight)	Biological half-life of tritium (h)	Water turnover
				(litres/day/animal)	(ml/kg0.75/day live weight)
Sheep
Uda	30.5	80.5 ± 1.2	139 ± 6.5	2.52 ± 0.36	208 ± 20.3
Yankasa	29.5	73.6 ± 0.8	116 ± 2.4	2.63 ± 0.22	222 ± 12.4
Goats
Sahel	12.6	77.8 ± 0.4	173 ± 12.6	0.86 ± 0.10	135 ± 9.5
Maradi	16.3	66.1 ± 2.8	139 ± 15.4	1.09 ± 0.15	142 ± 10.9

± standard deviation.
Source: Aganga et al., 1989.

4 Influence of diet type on water intake and weight gains of sheep and goats

Influence du régime alimentaire sur la consommation d'eau et les gains de poids des ovins et des caprins

Influencia del tipo de dicta en la ingesta de agua y el aumento de peso de ovinos y caprinos

	Sheep				Goats				SE1
	Group 1	Group 2	Group 3	Group 4	Group 5	Group 6	Group 7	Group 8
Initial weight (kg)	20.13	21.13	20.5	20.75	15.15	14.42	14.45	14.13	0.33
Final weight (kg)	22.05	25.13	24.58	25.25	16.10	16.35	16.25	16.80	0.32
Weight gain (kg)	1.925	4.125	4.075	4.5	0975	0.929	1.80	2.675	0.074
Average daily gain (kg)2,3,4,6,7	0.048	0.103	0.101	0.112	0.024	0.048	0.045	0.066	0.0018
Average daily hay intake (g)2,3,4	538.0	373.5	377.1	389.5	368.6	197.3	200.3	206.5	5.375
Daily concentrate meal intake (g)	-	-	-	271	-	-	-	167	-
Daily whole maize intake (g)	-	271	-	-	-	167	-	-	-
Daily ground maize intake (g)	-	-	271	-	-	-	167	-	-
Average daily water intake (ml)2,3,4,5,6,7	960.1	955.5	1013.3	1257.4	575.4	404.6	371.4	530.5	18.83
Average daily water intake (ml/kg0.73)	93.68	96.71	94.25	127.53	57.34	55.05	50.60	71.88	9.56

¹ Standard error.
² 1, 2, 3, 4 vs. 5, 6, 7, 8 significant at P<0.01.
³ 1 vs. 2, 3, 4 significant at P<0.01.
⁴ 2, 3 vs. 4 significant at P<0.01.
⁵ 2 vs. 3 significant at P<0.05.
⁶ 5 vs. 6, 7, 8 significant P<0.01.
⁷ 6, 7 vs. 8 significant at P<0.01.

Maradi goats - Chèvres Maradi - Cabras Maradi

Yankasa sheep - Moutons Yankasa - Carneros Yankasa

5 Effect of concentrate-to-roughage ratio on water consumption and weight gains of sheep and goats

Effet du rapport aliments concentrés/fourrages grossiers sur la consommation d'eau et les gains de poids des ovins et des caprins

Efecto de la relación entre los concentrados y los forrajes bastos sobre el consumo de agua y el aumento de peso de ovinos y caprinos

	Sheep				Goats				SE1
	Group 1	Group 2	Group 3	Group 4	Group 5	Group 6	Group 7	Group 8
Concentrate - to-roughage ratio	30:70	40:60	60:40	70:30	30:70	40:60	60:40	70:30
Initial weight (kg)	21.00	21.50	21.25	21.75	15.42	15.33	14.95	15.13	0.98
Final weight (kg)	25.68	27.20	27.83	29.45	17.52	17.92	18.05	18.73	0.90
Weight gained (kg)	4.67	5.70	6.57	7.70	2.10	2.60	3.10	3.60	0.13
Average daily gain2 (kg)	0.09	0.11	0.13	0.15	0.04	0.05	0.06	0.07	0.003
Average daily hay intake (g)	455.7	381.3	225.0	175.5	255.3	220.9	147.0	112.0	2.96
Daily concentrate intake (g)	207.7	276.9	414.6	483.8	121.92	162.26	243.38	284.4	21.62
Average daily water intake (ml)	1055.0	1327.8	1464.5	1566.2	611.5	749.2	846.1	1050.1	26.42
Average daily water intake (ml/kg0.73)2	105.91	129.16	141.63	146.92	79.11	96.30	109.31	133.09	4.19

¹ Standard error.
² Sheep vs. goats significant at P<0.01.

There was a linear increase in the water intake of the animals in relation to an increase in the concentrate content of the diet. The animals on 70-percent concentrate had a higher crude protein intake than those on 30-percent concentrate and, as a result, they required more water to clear the kidneys of nitrogenous waste.

In the trial on feed processing, the results show a significant difference in water intake (P<0.01) between sheep fed on milled concentrate and those fed on unmilled concentrate. The sheep fed on milled concentrate and chopped hay consumed more feed than the others, which means that they had a higher crude protein intake on the whole. Consequently, they required more water for excretion processes. Also, milling the feed might have affected the flow rate of the ingesta in the gut. The results of all the trials show that water intake of Nigerian sheep and goats is influenced by diet types, combinations and processing methods.

Physiological changes in water metabolism

The effects of age on the water requirements of sheep and goats showed significant differences (P<0.01) with regard to water intake. Generally, sheep drank more water per metabolical size than goats, while the older animals drank more than the young ones. The older animals were bigger in body size and, consequently, they required more water for proper digestion and utilization of the feed they consumed. With regard to gender, female goats drank more free water than male goats; however, the difference was not statistically significant.

Observations of water intake of ewes under various physiological states show that lactating ewes drank more water than pregnant and non-pregnant ewes. Water intake of the pregnant ewes was slightly higher than that of non-pregnant ewes, but it was significantly lower than that of the lactating ewes.

Effects of water deprivation

The intake of water is intermittent, while the loss of water is continuous. As a result, the animal is always faced with the problem of slow dehydration. Houpt (1977) stated that after a long period of dehydration the animal will be depleted of both water and primary electrolytes.

Two trials were conducted to study the effects of water deprivation on Yankasa sheep. The first trial examined the influence of intermittent watering on grazing sheep, while the second investigated the response of Yankasa ewes to water deprivation under various physiological states.

Results of the trial on grazing sheep showed that intermittent watering had a negative effect on the growth rate of the experimental animals during the dry season, causing them to lose weight. Those on daily watering, on the other hand, gained 66 g daily. During the rainy season, all animals gained weight in spite of the watering intervals imposed on them. This would appear to be the result of the high moisture content of the pasture (about 80 percent). The effect of water deprivation, therefore, was obvious only during the dry season trial.

The decrease observed in mean live-weight gain with increased water deprivation confirmed the findings of Umunna et al. (1981) in their study of sheep deprived of water during the dry season. The animals on 72-h and 96h watering intervals grew lean and staggered whenever they attempted to graze, this becoming more pronounced towards the end of the study. The hair coat was rough and dry and came off easily with mere touching after the experiment had progressed for 40 days. This observation agreed closely with the findings of Schoen (1968), who reported skin dehydration and hair loss in water-deprived East African goats.

Water deprivation raised blood biochemical constituents significantly. The high values obtained in water-deprived ewes showed signs of haemoconcentration caused by dehydration. Prolonged watering intervals appeared to impose serious stress on the animals during the dry season. Variations in rectal temperature were slight among animals on varying watering intervals. A decrease in urine output and production of dry faeces was observed with the water-deprived animals during the dry season. These animals appeared to drink in a compensatory fashion whenever they had access to drinking-water. Water deprivation also significantly lowered the respiratory rate in sheep. Jaw movements were drastically reduced with long watering intervals as well, indicating that rumination was seriously impaired by water deprivation.

Water deprivation seriously affected the Yankasa ewes. The lactating ewes were most significantly affected (P<0.01), since the milk yield dropped and the growth rate was also severely lowered. Water restriction seriously affected the milk yield. The ewes on a daily watering schedule produced the highest quantity of milk, and milk production dropped by more than 50 percent when the watering interval was increased to 72 hours.

The milk produced by water-deprived ewes was more viscous; milk composition studies showed that the milk consisted of about 80 percent water. Consequently, the protein, fat, ash and non-fat solids composition of the ewes' milk increased with more severe water restriction.

The reproductive performance of the pregnant ewes was also adversely affected by water deprivation. The rates of abortion and stillbirths, as well as the lamb mortality rate, rose as the ewes were increasingly deprived of drinking-water. Pregnant ewes subjected to a 72-h watering schedule appeared uncomfortable, very nervous and bleated more frequently. Pregnant ewes that received daily watering had heavier lambs at birth. This is in agreement with findings by Lynch et al. (1972), who reported a significant reduction in the birth weights of the lambs of ewes deprived of drinking-water.

Bibliography

Aganga, A.A., Umunna, N.N., Okoh, P.N. & Oyedipe, E.O. 1986. Water metabolism of ruminants - a review. J. Anim. Prod. Res., 6: 171-181.

Aganga, A.A., Umunna, N.N., Oyedipe, E.O. & Okoh, P.N. 1989. Breed differences in water metabolism and body composition of sheep and goats. J. Agric. Sci. (Camb.), 113: 255-258.

Gihad, E.A. 1976. Intake, digestibility and nitrogen utilization of tropical natural grass hay by goats and sheep. J. Anim. Sci., 43: 879-883.

Houpt, T.R. 1977. In Duke's physiology of domestic animals. Ithaca, NY, and London, Comstock Publishing Associates (a division of Cornell University Press).

Lynch, J.J., Brown, G.D., May, P.F. & Donnelly, J.B. 1972. The effect of withholding drinking water on wool growth and lamb production of grazing Merino sheep in a temperate climate. Aust. J. Agric. Res., 23: 659-668.

Macfarlane, W.V., Howard, B. & Morris, R.J.H. 1966. Water metabolism of Merino sheep shorn during summer. Aust. J. Agric. Res., 17: 219-225.

Panaretto, B.A. & Till, A.R. 1963. Body composition in vivo. II. The composition of mature goats and its relationship to the antipyrine, tritiated water, and N-acetyl-4 amino-antipyrine spaces. Aust. J Agric. Res., 14: 926-943.

Schoen, A. 1968. Studies on the water balance of the East African goat. East Afr. Agric. For. J., 34: 256-262.

Umunna, N.N., Chineme, C.N., Saror, D.I., Ahmed, A. & Abed, S. 1981. Response of Yankasa sheep to various lengths of water deprivation. J. Agric. Sci. (Camb.), 96: 619-622.