Varying levels and modes of supplementary sodium were administered to a herd of 30 browsing single-birth West African Dwarf (WAD) kids from 12 to 32 weeks of age in a factorial experiment of two trials to evaluate growth, development and health.

During each trial experimental animals were randomly allotted to five groups of six goats comprising 3 males and 3 females. Three groups were each given drinking water containing 0.3, 0.4 and 0.5% of supplementary sodium, while a 4th group received no sodium supplement. Group 5 had sodium provided by salt blocks placed in their pens. Parameters investigated, including growth(body weight), development (withers height and thoracic girth), reproduction (age at puberty) and health records, indicated positive responses to sodium supplementation by browsing goats compared to controls. Optimum changes in body weight and development occurred with sodium supplementation of between 0.4 and 0.5% in the drinking water, with the upper limit of supplementation applicable in the dry season.

Animals which received their sodium supplements via drinking water attained sexual maturity 2 to 3 weeks faster compared to other treatments. Mineral consumption was very low for the group receiving a salt block. Also a more healthy state was maintained during the course of the study among animals which ingested supplementary sodium via their drinking water.

In exclusive grass feeding of ruminants the daily sodium intake from the fodder often does not meet requirements (Kemp and Guerink 1978). Furthermore, the daily sodium chloride loss through perspiration can amount to 5 g per 100 kg body weight (Kuthe 1976). Sodium is, therefore, often the mineral element necessary for supplementation throughout the tropical regions of the world (Sutmöller et al 1966). Salt has become the farmers valuable "carrier" of other mineral elements whenever supplementation is practiced (McDowell et al 1993).

The beneficial responses of cattle and sheep to mineral supplementation have been investigated (Arroyo and Mauer 1982; Morris and Gartner 1971; Walker 1957). However, studies on the mineral metabolism of the goat have been neglected and data available are still fragmentary. Larson (1978) pointed out that mineral research conducted with goats has been often not to determine mineral requirements of the goats but to use them as a less expensive model in place of cows.

Yet there are more than 400 million goats around the world producing more than 4.5 million tons of milk and 1.2 million tons of meat for human consumption (Haenlein 1978; FAO 1977).

The objective of this dose-effect study of early-weaned West African Dwarf (WAD) goats reared to puberty was: 1) evaluate biological responses to provision of Na supplement in a modified traditional system of management; 2) ascertain the best mode of supplementing Na to browsing goats; and 3) determine appropriate levels of Na for optimum productivity.

Goats were obtained from various sources within and around the town of Ibadan. Animals were selected as progeny of first-kidding does, other criteria of selection being type of birth, age, body weight and health. It was found impossible to obtain a source of homogenous materials and an original intention to purchase kids from only one source to reduce genetic variation had to be abandoned due to difficulty in collecting a sufficient number of kids. A repeat of the study was carried out as a confirmatory trial.

In each trial (20 weeks) the experiment commenced with thirty single-birth, healthy-looking ruminating WAD kids randomly divided into five groups of six goats. Each group was composed of three male and three female kids estimated at three months of age.

In trial I body weight of animals ranged between 4.5 to 4.9 kg (mean 4.8 ± 0.16 kg) with the experiment lasting for 8 weeks during the dry season (February - April) and 12 weeks during the wet season (April - July).

During trial II, body weight of animals ranged between 4.3 to 5.0 kg (mean 4.7 ± 0.19 kg) with the experiment lasting for 10 weeks each during the dry season (February - April) and wet season (April - June).

The experiment was conducted at the far northern end of the University of Ibadan campus comprising the University Teaching and Research Farm and parts of Abadina Village. The University of Ibadan is located in southwestern Nigeria lying within the humid zone of West Africa. This area has an annual rainfall of between 1250 and 1800 mm. The rainy season is slightly bimodal, with peaks in July and October. The dry season stretches from mid-November to mid-March. Temperatures range from 27 to 32 ?C and relative humidity averages 80 to 90% (ILCA 1982).

Over the years there has been cultivation of the nonpastoral areas of the portion of land not occupied by farm buildings. Therefore the study area enclosed scattered plots of food crops such as cassava and maize which resulted in the residues, such as the stems and dried leaves of cassava and maize stovers, being available to experimental animals.

Legumes and grass species in the browsing area included Leucaena, Gliriciddia, Centrosema, Panicum, and Cynodon. The major species of trees of nutritional importance to goats were pawpaw, palm and mango which shed their leaves frequently and are edible.

The experimental animals were fed indoors for one week with a commercial concentrate as a basal ration in order to stabilize them. They were vaccinated against peste petite ruminantes (PPR) and given a complete course of antibiotics (Procaine Penicillin and Streptomycin) to provide a common health status among the goats. The animals were dipped with Asuntol and drenched with piperize dihydrochloride against ecto and endo parasitic organisms, respectively.

The animals were housed in pens of simple enclosure at night. The walls were made of bricks and covered with corrugated iron sheets. There was adequate ventilation in their pens and sufficient protected from rains at night. Bedding of wood shavings was provided on pen floors and was changed regularly throughout the experimental period.

The goats were turned out together to browse within the study area every morning and were returned to their pens at night throughout the period of study. Individual animals were recognized by means of numbered neck tags and given full liberty as "experimental materials" to browse freely within all parts of the study area.

Morning browsing started at about 0730 hours and lasted until 1230 hours while the hours of between 1300 to 1830 were allowed for the evening browzing on every fine day. Between the morning and evening hours of browsing, about 30 minutes were used to check in experimental animals into their various pens where known weights of sodium from a block of mineral mixture (Gishirin Shanu) composed of 97% NaCl were dissolved in drinking water at varying concentrations and fed to the respective experimental groups.

Veterinary services were rendered to the animals only when it became necessary for the survival of experimental animals and records of health were kept.

The study consisted of five treatments as follows: Treatment I was a control consisting of cool, clean tap water to which no sodium supplement was added (the small proportion of sodium usually present in tap water was disregarded). Animals in Treatments II, III and IV received tap water to which sufficient sodium supplement had been dissolved (common salt was the sodium source) to give sodium percentages of 0.3, 0.4 and 0.5, respectively. In Treatment V goats had access to their sodium supplement provided as a mineral salt block which was changed regularly to prevent spoilage. Except for salt other minerals were in low concentrations in relation to requirements.

The drinking water containing sodium was provided to the animals and ingested as the first |drink|. Afterwards, tap water to which no sodium had been dissolved was supplied freely in individual plastic buckets.

The following records were obtained: 1) Body weight - recorded on a weekly basis in the morning on empty stomach; 2) Development (including thoracic girths and withers height) - height at withers was measured as vertical distance between ground to point of withers, and thoracic girth was measured as the smallest circumference of the body immediately behind the shoulders. Both parameters were measured weekly; 3) A daily inspection was made, attention being paid to physiological and behavioral manifestations associated with sexual development; and 4) Records of general animal health were maintained.

Data from growth and development were subjected to factorial analysis using the SAS Program, while Analysis of Variance and Duncan's Multiple Range (P=0.05) tests were used to compare means (Snedecor and Cochran 1980).

As shown for both trials, effects of supplementary sodium, season or sex were not significant (P>0.05) on body weight changes (Table 1). Trial I indicated a significant (P<0.05) effect of sodium supplementation on height at withers, with a minimum level of 0.4% required for optimum gains in withers height (Table 2). In Trial II, no differences (P<0.05) existed between weekly means of withers height.

Table 1: Mean weekly changes in body weight (kg) for goats receiving varying levels of sodium
		Trial I		Trial II
Na	Sex of	Season of Year		Season of Year
%	Animal*	Dry, 91	Wet, 91	Dry, 92	Wet, 92
0	M	0.15±0.07**	0.09±0.01	0.08±0.05	0.13±0.05
	F	0.04±0.02	0.08±0.06	0.0±0.08	0.19±0.01
0.3	M	0.12±0.05	0.14±0.01	0.08±0.05	0.22±0.07
	F	0.08±0.06	0.09±0.07	0.06±0.06	0.21±0.04
0.4	M	0.19±0.08	0.09±0.02	0.10±0.04	0.23±0.05
	F	0.16±0.07	0.30±0.02	0.06±0.07	0.20±0.05
0.5	M	0.13±0.02	0.15±0.10	0.18±0.05	0.18±0.04
	F	0.59±0.07	0.21±0.04	0.12±0.04	0.13±0.06
Salt	M	0.13±0.10	0.15±0.07	0.08±0.07	0.12±0.05
block	F	0.03±0.01	0.05±0.01	0.06±0.05	0.13±0.03

*M = male and F = female
**Mean±standard error

There were greater but not significant (P>0.05) decreases observed in thoracic girths among experimental goats during the dry compared to the wet season in Trial II (Table 3).

In Trial II, a significant (P<0.05) effect of Na was observed in thoracic measurements of browsing goats, with better performances on thoracic girth during the wet compared to the dry season.

Sodium supplementation of 0.5% resulted in the best performances in thoracic girth during both seasons of the study.

Table 2: Mean (±standard error) weekly changes in height at withers (cm) for goats receiving varying levels of sodium
		Trial I		Trial II
%	Sex of	Season of Year		Season of Year
Na	Animal#	Dry, 91	Wet, 91	Dry, 92	Wet, 92
0	M*	0.15±0.05ab	0.18±0.02ab	0.04±0.04	0.22±0.09
	F	0.04±0.02b	0.11±0.08ab	0.04±0.04	0.14±0.02
0.3	M	0.15±0.06ab	0.24±0.07ab	0.04±0.02	0.24±0.10
	F	0.00±0.00b	0.06±0.05ab	0.04±0.09	0.22±0.07
0.4	M	0.19±0.04ab	0.22±0.09ab	0.10±0.04	0.11±0.05
	F	0.08±0.04ab	0.15±0.06ab	0.06±0.03	0.19±0.06
0.5	M	0.19±0.04ab	0.22±0.09ab	0.10±0.04	0.11±0.05
	F	0.17±0.05ab	0.33±0.01a	0.13±0.04	0.14±0.05
Salt	M	0.08±0.04ab	0.11±0.08ab	0.06±0.03	0.11±0.05
block	F	0.08±0.08ab	0.06±0.04ab	0.06±0.03	0.10±0.04

#M = male and F = female
a,b: Means in the same trial with different superscripts differ (P<0.05)

Table 3: Mean (±standard error) weekly changes in thoracic girth (cm) for goats receiving varying levels of sodium
			Trial I			Trial II
%	Sex of		Season of Year			Season of Year
Na		animal#		Dry, 91	Wet, 91		Dry, 92	Wet, 92
0		M#		-0.04±0.01	0.03±0.02		0.02±0.01cde	0.13±0.02bcd
		F		0.31±0.05	0.03±0.02		0.02±0.02de	0.03±0.01cde
0.3		M		0.06±0.02	0.12±0.05		0.04±0.08cde	0.08±0.0bcde
		F		-0.04±0.01	0.11±0.01		0.02±0.01cde	0.08±0.07bcde
0.4		M		-0.02±0.04	0.13±0.02		0.04±0.08cde	0.17±0.05abcd
		F		0.00±0.00	-0.06±0.02		0.06±0.09cde	0.15±0.07abcd
0.5		M		0.00±0.00	-0.15±0.01		0.19±0.09abc	0.32±0.07a
		F		0.29±0.02	0.21±0.01		0.08±0.07bcde	0.26±0.05ab
Salt		M		-0.06±0.02	0.09±0.04		-0.08±0.09e	0.06±0.01cde
block		F		0.00±0.00	0.07±0.04		0.02±0.02de	0.00±0.00cde

#M = Male and F = Female
abcde: Means in the same trial with different superscripts differ (P<0.05)

Table 4: Mean reproductive performances of goats given varying concentrations of supplementary sodium during two trials
		% Supplementary Sodium
		0		0.3		0.4		0.5		Salt block
Item		M	F	M	F	M	F	M	F	M	F
Start of experiment
to puberty (wks)
Trial	I	18	18	18	18	14	17	15	18	19	19
Trial	II	17	18	15	17	15	16	17	17	18	18
Liveweight at puberty (kg)
Trial	I	8.0	5.8	7.4	6.5	7.4	6.1	7.0	7.7	6.5	5.9
Trial	II	6.5	6.7	7.0	7.2	6.5	6.6	7.5	7.0	6.3	6.2

Table 5: Observations on health status and general activities of experimental goats given varying treatments of supplementary sodium during Trials I and II
Supplementary	Dry Season	Wet Season
Na (%)	(Feb.- Mar.)	(April - Oct.)
Trial I
0.0	Licking of pen wall.	Eye discharges which
	Licking of body of	responded to chloram-
	other animals, espe-	phenicol treatment.
	cially immediately	Diarrhoea which responded
	after returning from	to treatment with
	browsing.	tetracycline or terramycin
	Rough dull coat.	soluble powder.
	Restlessness.	Mange infestation which
		responded to treatment
		with Ivomec.
		Regular dipping to remove
		lice infestation.
0.3	No symptomatic	Eye discharges which res-
	conditions observed.	ponded to chloramphenicol
		treatment.
		Cold and catarrh which
		responded to treatment.
0.4	No symptomatic
	conditions observed.
0.5	No symptomatic	Only one animal with
	conditions observed.	ocular discharge (not
		treated).
Salt	Licking of walls and	The smallest female animal
block	drinking of urine.	obtained in this treatment
		Diarrhoea (treated)
		at the end of experiment.
Trial II
0.0	Licking of urine of	Eye discharge responded to
	other animals, espe-	treatment with chloram-
	cially those of mem-	phenicol. Cold and catarrh
	bers of treatments	but animals responded to
	0.4 and 0.5% Na.	antibiotic treatment.
	Restlessness.	One female animal died
	Diarrhoea but animals	and was replaced by one of
	responded totreatment	a similar body weight from
	with tetracycline or	reserve unit.
	terramycin soluble
	powder. Smallest
	female animal was
	found in this treat-
	ment at the end of
	experiment.
0.3	Mange infestation	Few diarrhoea animals and
	which responded to	they responded to treat-
	treatment with	ment with terramycin
	Ivomec.	soluble powder.
0.4	One male animal	One male animal with
	manifested epileptic-	swollen jaw (not treated
	lick symptoms (No	but recovered).
	medical attention	Few mange problems
	given).	(treated).
0.5	Mange/lice problems
	(treated).
Salt	Lice infestation	Heavy mange/lice infesta-
	(treated).	tions (treated).
	Restlessness.	Diarrhoea.
	Unthrifty appearance.
	Consumption of sand.

Puberty manifestations were observed first in the group of animals receiving 0.4% supplementary sodium (Table 4). In males, this occurred at the 14th week of experiment when animals attained a mean liveweight of 7.4 kg. Females in this group attained puberty at week 17. Attainment of puberty occurred during week 15 in male goats and week 18 in females in the group receiving 0.5% supplementary sodium. Both male and female goats on the 0.3% sodium exhibited puberty characteristics at week 18 when the males weighed 7.4 kg and the females 6.5 kg. Animals receiving no sodium supplement did not show any sexual behavior until week 18, while behavioral tendencies were observed a week before the end of the study in the group receiving supplementary sodium as salt blocks.

Table 5 presents observations made on animal health. Prominent behavioral tendencies common among goats given no sodium supplement and those whose sodium were provided as salt blocks included licking of pen walls as well as body and urine of other animals, especially of those ingesting 0.5% supplementary sodium. Animals on 0% supplementary sodium showed unthrifty appearances, restless conditions, ocular discharges (especially during the wet season) and also were most affected by mange infestation. Goats consuming 0.5% sodium-treated water recorded the least health problems.

There was no significant effect of of any of the variable factors (P<0.05) on body weight changes, while both withers height and girth sizes of goats were influenced (P<0.05) by supplementary sodium. Goats responded positively to provision of supplementary sodium by increases (P<0.05) in their development parameters. The importance of mineral supplementation on overall production of cattle in the Llanos regions of Colombia for instance, was reported by Miles and McDowell (1983) who stated that mineral supplementation dramatically increased all production parameters. In particular, Walker reported a growth response in browsing cattle in Rhodesia to sodium chloride supplement, while McClymont et al (1957) observed a growth response to sodium chloride in sheep given high grain diets containing 0.01 to 0.06% sodium after a long period of undernutrition. In their second experiment McClymont et al (1957) showed that the effect was due to Na rather than Cl, this finding being confirmed by Morris and Gartner (1971) who showed an unequivocal growth response in cattle to Na supplementation. McDowell et al (1993) reported weight losses due to NaCl deficiency resulting from lack of appetite, while Maynard et al (1979) indicated that dietary Na deficiency lowers utilization of ingested protein and energy and limits production.

Consumption of salt blocks by animals in Treatment V was extremely low. Observed inability of goats to accept and lick salt in block form, may be related to their lack of past dietary experience with salt blocks since these animals were purchased from local sources where they were not usually provided with supplementary mineral blocks. Provenza et al (1988) stated that acquisition of ability of animals to select or accept ingredients for adequate nutrition is a function of previous experience, while Arnold and Maller (1977) in supporting this learning theory observed that sheep for instance, which had past experience with several contrasting nutritional environments displayed a marked difference in their grazing preferences compared to other sheep without a similar past experience. It is also possible that goats did not accept mineral blocks simply indicating their difficulty in conforming to conventional feeding methods.

Goats which received water containing sodium chloride reached puberty at between 7 to 35 days earlier compared to other groups (Table 4), suggesting beneficial effects of supplementary sodium on reproductive performance. Increased reproductive performance resulting from mineral supplementation generally have been reported (Arroyo and Mauer 1982; McDowell and Conrad 1977; Sinclair and Jones 1968).

Goats which received no sodium-treated water exhibited sodium deficiency clinical signs (Table 5) by licking pen walls, as well as bodies and urine of other animals in their instinctive search for sodium. They also suffered most from problems of diseases and parasites. On the other hand, animals consuming sodium-treated water were active, bright in appearance and showed more resistance to incidences of diseases and parasites.

There were beneficial responses of WAD goats to sodium supplementation. From weaning until puberty, a supplementary sodium level of between 0.4 and 0.5% in the drinking water would seem to be appropriate in meeting sodium requirements, with the upper limit of Na being suggested during the dry season. It is recommended that traditionally managed goats be provided their Na supplement dissolved in drinking water unless the farmer has the time to take his herd through a teaching practice with Na salt blocks.

We gratefully acknowledge some analytical assistance provided by International Institute of Tropical Agriculture (ITA), Ibadan. The first author especially, wishes to thank the Federal University of Agriculture, Makurdi for funding this research.

(Received 1 May 1995)