Intake, digestion and feeding behaviour of the one-humped camel stall-fed straw-based diets

Intake, digestion and feeding behaviour of the one-humped camel stall-fed straw-based diets

Intake, digestion and feeding behaviour of four 200 kg one-humped camels fed long or chopped straw-based diets were determined in two 2 x 2 Latin Squares. Wheat straws were offered ad libitum while a concentrate containing 96 % wheat bran, 3 % mineral supplement and 1 % urea was restricted to 0.5 kg as fed per day.

Chopping the straw did not affect (P>.05) any of the investigated parameters. Mean straw intake was 2.36 kg DM/d, which represented 84.1 % of the total DM intake. The camels spent 39 % of their time ruminating, 29 % eating and 32 % resting. About 97 % of the eating activity occured during daytime versus 44.4 % for ruminating and 45 % for resting.

Apparent digestibilities of DM, OM, CP and CF were: 55, 58, 42 and 65 %, respectively.

It was concluded from comparison of these results with literature data on cattle and sheep that camel did not appear to digest more extensively poor quality roughages.

One-humped camel (Camelus dromedarius) thrives in an arid environment where the supply of good quality forages is very limited. Its selective retention of feed particles in the fermentation chambers (Heller et al 1986) may be one of the many factors responsible for its adaptation to low quality feeds. Retention in the gut is related to the size of offered forage particles, and to eating and ruminating behaviour.

In this study, intake, digestion and feeding behaviour of the camel fed long or chopped straw-based diets where investigated.

In this experiment which began in March 1989, four 200 kg one-humped camels aged about 16 months were housed in an open barn on concrete floors and confined by tying one of their anterior feet to the wall. During an 8 week period of adaptation they were offered wheat straw ad libitum supplemented with 0.5 kg of a concentrate based on barley. At the same time, the camels were accustomed to the presence of the researchers, to fecal collecting harnesses and to the ingestive behaviour recording clock.

Following this adaptation period, the camels were used in a 2 x 2 Latin Square replicated twice. The treatments were wheat straw in the long form with an average length of 15 cm, and chopped wheat straw with an average length of 8.5 cm. Thus, in each experimental period, two camels received the long straw while the others received the chopped one.

Each of the two experimental periods consisted of a 10-day preliminary period and a 9-day period for fecal collection and eating behaviour recording. During the experimental periods, sufficient straw was offered twice daily at 08.00 and 14.00 hours.

A restricted quantities (0.5 kg/d) as fed of a concentrate made of wheat bran, urea and mineral supplement was given at 14.00 hours in one of two feeders for each camel. The chemical analysis of the concentrate as given in table 1. The amount of concentrate was restricted to give a diet containing about 80 % straw similar to one which might ensure maintenance nutrient intake. The camels had access to their assigned diets and water at all times.

Table 1: Chemical composition of the straws and the concentrate

Components	Long straw	Chopped straw	Concentrate*

Dry matter	92.3 (1.5)	92.9 (2.5)	89.9 (1.0)
	---------------------------------- % of DM ----------------------------------
Organic matter	94.3 (0.5)	95.2 (0.3)	92.2 (0.9)
Crude protein	3.8 (0.9)	3.8 (0.5)	18.3 (0.4)
Crude fiber	42.4 (3.3)	42.8 (3.0)	5.1 (1.6)

Measurements of time spent eating, ruminating and resting were made with a vibracorder (Ruckebush and Bueno 1973) for two periods of 24 h. For measurements of digestibility, total fecal collections were made twice or three times a day in collection bags made of cloth (outside) and plastic (inside).

The concentrate and offered and refused straw, which were collected and weighed before each morning meal, were sampled daily for DM determination and subsequent chemical analyses. Feces were dried at 80 °C and sampled for chemical analyses.

The chemical analyses of feeds, refusals and feces were made by standard procedures on dried materials.

Statistical analyses were conducted according to procedures for repeated (multiple) Latin Square design.

The daily total DM intakes (DMI) were relatively low: 2.73 to 2.88 kg (table 2). Nitrogen intake might have limited DMI since calculated crude protein contents of the diets were only 6.0 % and 6.2 % of DM. Furthermore, it should be recognized that the animals were young which might have affected voluntary intake; using older camels could have led to higher intake as reported by Farid et al (1980) when camels weighing 538 kg ate 3.6 kg of a diet made of straw and legume hay. Maloiy (1972) found daily intakes by stall-fed camels averaging between 190 and 460 kg varying from 1.3 to 5.3 kg DM of poor chopped hay from a mixed pasture containing mainly star grass (Cynodon dactylon). The chemical composition of straw offered and refused (table 2) shows that the camels selected the more nutritive parts of the straw. They seemed to prefer more nitrogen-rich parts. Such behaviour has been reported for camels on pasture by Maloiy (1972) who indicated that plants selected by camels had high water and protein contents.

Table 2: Intake and chemical composition of refused straw

Components	Long straw	Chopped straw	Mean

Intake
Total, kg DM/d	2.88 (.05)	2.73 (.04)	2.80 (.10)
Straw, kg DM/d	2.44 (.05)	2.28 (.04)	2.36 (.10)
Straw/total, %	84.7	83.5	84.1
Water, litre/d	6.0 (2.3)	5.0 (1.6)	5.5 (1.3)

Refusal of straw *	12.3 (2.2)	18.2 (1.5)	15.2 (3.7)

Composition of refused straw **
Organic matter	101.1 (1.1)	100.9 (.3)	101.0 (.5)
Crude protein	79.0 (22.7)	79.5 (8.4)	79.2 (15.9)
Crude fiber	106.4 (6.7)	105.0 (5.3)	105.7 (5.7)

Unexpectedly, chopping the straw tended to decrease its voluntary intake. Straw intakes by camels found in this study are intermediate between those reported for sheep (Abdouli et al 1988; Xande 1978) and cattle (Hoden 1972, Abdouli et al 1988). Parameters and patterns of feeding behaviour are shown in tables 3 and 4. The camels spent about 40 % of their time ruminating and 30 % for eating or resting. Sunrise initiated eating which was intensified following meal distribution and ceased shortly after sunset. Thus while eating occured mainly during the day, ruminating and resting were almost equally partitioned between the day and the night.

Table 3: Total intake and parameters of the feeding behaviour of camels fed straw ad libitum

Components	Long straw	Chopped straw	Mean

Voluntary intake, g DM/d	2609 (95.5)	2495 (139.6)	2552 (126.4)

Eating time, min/d	423 (50)	424 (26)	423 (37)
% of 24 h	29	29	29

Eating rate, g DM/h*	370 (41)	354 (17)	362 (30)

Ruminating time, min/d	580 (56)	542 (70)	561 (62)
% of 24 h	40	38	39

Ruminating efficiency, g DM/h **	270 (18)	276 (50)	273 (35)

Resting time, min/d	437 (60)	475 (49)	456 (54)
% of 24 h	30	33	32

* Eating rate = voluntary intake, (g DM/d) divided by eating time, (h/d)
** Ruminating efficiency = voluntary intake, (g DM/d) divided by ruminating time, (h/d)
( ) Standard deviations

Chopping the straw did not modify significantly (P>.05) feeding parameters nor pattern; only slightly shorter ruminating and longer resting times were associated with the chopped straw. Also a small decrease in eating rate (voluntary intake in g DM/d divided by eating time in h/d) due to a reduced intake was observed and indicated that the camels might have had more ability to select through chopped straw.

Table 4: Partition of feeding activities in camels fed straw ad libitum (% of time of each activity)

		---------------------------- D a y t i m e ----------------------------
Diets	Night time	Before	Between	After 2nd
		1st meal	meals	meal

Long straw
Eating	1.5	3.9	44.1	50.5
Ruminating	56.0	14.0	24.0	6.0
Resting	54.6	3.5	9.7	32.1

Chopped straw
Eating	3.7	6.5	34.7	55.0
Ruminating	55.2	12.1	26.7	6.0
Resting	56.2	3.4	14.5	25.5

Mean
Eating	2.6 (2.3)	5.2 (4.1)	39.4 (7.3)	52.8(8.7)
Ruminating	55.6 (6.0)	13.0 (2.5)	25.3 (7.3)	6.0(7.4)
Resting	57.4 (6.0)	3.5 (2.1)	12.3 (5.8)	28.8(5.3)

No reports on ingestive behaviour and related activities in camels are available to us, and only indirect comparison with other domestic ruminants can be made. It has been reported (Thomas and Campling 1977) that stall-fed sheep and cows offered long grass hay ad libitum, ate for 373 and 324 min/d, respectively, which are shorter times than the 423 min/d spent by the camels; the ruminating times were, however, similar for sheep (540 min/d), cows (542 min/d) and camels (542 and 580 min/d). The eating rate and the ruminating efficiency (voluntary intake, in g DM/d divided by ruminating time, in h/d) for the camels are about two times higher than those for sheep (185 and 128 g DM/h for eating rate and ruminating efficiency, respectively) and 4 to 5 times shorter than those for cows (2088 and 1248 g DM/h for eating rate and ruminating efficiency, respectively). This does not necessarily imply that camels chew feed finer than do cows since feed particles as large as 3 cm have been found in the intestine of camels (Heller et al 1986); whereas for bovines, particles larger than 1 mm do not pass through the omasum. On anatomical grounds, the omasum of the camel is known to lack the well developped and juxtaposed leaves that screen coarse particles (Abdouli H unpublished).

Coefficients of apparent digestion of the diets are presented in table 5. They show that only crude fiber digestibility (CFD) was somewhat high. When the contribution of the concentrate was removed assuming its CFD was 30 % (Demarquilly et al 1978), then the digestibilities of the straw CF were 67.3 and 63.5 % for long and chopped straw, respectively.

Chopping the straw did not affect (P>.05) the digestibility of DM, OM and CF. This is in agreement with the similarity of the total intakes, and the feeding behaviour associated with the two forms.

Table 5: Apparent digestibility (%) of the dry matter, organic matter, nitrogen and crude fiber of the diets

Components	Long straw	Chopped straw	Mean

Dry matter	57 (1.4)	54 (6.5)	55 (1.7)
Organic matter	60 (2.2)	57 (.87)	58 (2.1)
Nitrogen	42 (4.6)	41 (1.2)	42 (3.2)
Crude fiber	66 (4.6)	63 (4.6)	65 (4.7)

When coefficients of digestion for camels were compared with corresponding values for sheep and cattle, camels did not appear more efficient in digesting DM, OM or CF of poor quality roughage diets. Thus, Abdouli et al (1988) reported DM digestibility of 60.7 % for sheep offered long straw ad libitum with 200 g barley- based concentrate; the digestibility of straw CF being 65.1 %. In a compartive study, Maloiy (1972) found that Zebu steers digested hay better than camels; the DM digestibilities were: 64 vs 50 %. Thomas and Campling (1977) reported digestibilities of 69.0 and 69.7 % for cellulose of hay offered to sheep and cows, respectively.

It is concluded that although the camels spent a large part of their time eating, they had limited intakes of straw. Their ruminating efficiency was low but this did not seem to give them advantage over other domestic ruminants to digest better fibrous materials. Chopping the straw did not affect the apparent digestibility, not did it modify the feeding behaviour. However, the low nitrogen intake might have masked the ability of the camel to consume a larger quantity of straw, and to digest it extensively.

The authors are grateful to Dr C Kayouli for providing the vibracorder clock, and to Mr R Sansoucy for reviewing the manuscript.

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