Effect of dietary supplementation, sex and birth type on body weight of desert ewes and their lambs’ growth performance in semi arid area of Kordofan State, Sudan

A O Idris, M B Elemam, C Kijora, F M El-Hag and A M Salih****

Faculty of Natural Resources and Environmental Studies, Peace University, P.O. Box 20, El Fulla, Sudan.
abuelgoni2002@hotmail.com
* M B Elemam Department of Animal Production, Faculty of Agriculture and Natural Resources, University of Kassala, P.O. Box 12, New-Halfa, Sudan.
Department of Plant and Animal Sciences, Humboldt-University of Berlin, Philippstr.13, Building No. 9, 10115 Berlin, Germany.
* Agricultural Research Corporation, El-Obeid Research Station, Box 429, El Obeid, Sudan.
**** Faculty of Animal Production, University of Khartoum, P.O. Box 32, Khartoum-North, Sudan.

Abstract

The aim of the study was to investigate the effects of supplementation during mating and at late pregnancy on ewes body condition score and lambs growth rate in the dry season. A total of 341 ewes were selected during mating season. The animals were randomly assigned to four groups. Group one was used as a control, the second, third and fourth group were supplemented with rations containing groundnut cake (GNC), groundnut cake and molasses (GNC-M) and Roselle seeds and molasses (RM). All ewes in the three supplemented groups were flushed and steamed-up, while the control group received no supplements. Ewes were offered 450 g / head of the ration every three days at the watering periods and the rams 600 g / head for three days.

Body condition score (BCS) of ewes were estimated in breeding, mid pregnancy and lambing period. The lambs were weighed at birth, and each two weeks till day 120 post-partum. The results obtained indicated that, supplementation improved the BCS compared with farmer practice. The study indicated that, the pre-partum supplementation of the dams increased lamb daily growth rate before weaning.

Key words: Body condition, flushing, lactation, mating, pregnancy

Introduction

Sudan desert sheep and their crosses makeup about 80 % of the sheep found in Sudan and mainly predominant north of 12º N (Devendra and Mcleroy 1982), they are raised mainly under harsh dry land farming conditions for meat production (Khalafalla and Sulieman 1992). El Hag (2001) reported that, the nutritional limitation, low nutritive value of the range, high ambient temperature, scarcity of feed and water are have great effect on the production of the sheep in semi arid area of Kordofan state as compared to that in temperate regions.

The most critical period for grazing sheep in the semi desert zone of Sudan is from February to June, when the ambient temperature becomes hot and range grazing is scanty and depleted of nutrients (Cook and Fadlalla 1987). Shortage feed in mating season is the main factor, that effect to sheep production in the range land of Kordofan, taking into account that natural pasture by product are poor in their quality and most the range exposed to over grazing, especially near the water recourses. Seasonal nutritional status and husbandry affect sheep production characteristics (El Hag et al 2001). Lambing desert sheep occurs all the year –round but the main breeding seasons are either January–March or October–November (Mukhtar 1985). Nomadic sheep flocks spend the dry season near watering yards. During winter months, when ambient temperature is mild and the range contains some green fodder, herds can extend the watering intervals from 10 to 15 days. After winter grazing when climatic conditions becomes harsh, so the watering interval is reduced to between 3 to 5days (Mukhtar 1985).

The control of breeding is by tied the reproductive organs of the ram (Kunan), this is a common practice to control breeding which is usually carried out during (February -March) with subsequent lambing during autumn (July-September).This practice would ensure good grazing for lambs. However, weaned lambs may be exposed to long dry winter and summer period when agricultural by products and residues, especially groundnut seed cake and hay are widely used by sheep owners.

Material and Methods

Study area

The study was conducted at Agricultural Research station, El-Obeid, North Kordofan state,(latitude11˚:15̀-16˚:30̀ N and longitudes 27˚-32˚ E ), Sudan. Most of North Kordofan state lies within arid and semi-arid ecological zones. The average maximum temperature varies between 30 and 35˚C during most of the year with peaks above 40˚C during hot summer. The rainy season extends from July to October, reaching it peaks in August .The annual rainfall ranges from 75 mm in the extreme north about 500mm in south with average 280 mm (Technoserve 1987). The northern part of area is covered with sandy soils which is originally either stabilized or mobile sand dunes. The southern part is predominantly silty clay, non cracking clay soil with small patches of cracking clay. The vegetation varies from north to south. In the north grass land and shrubs predominate while bushes and trees are common in the south (Harrison and Jackson 1958).

A total of 341 desert ewes (1 to 6) years old reared in natural range condition were selected during the normal breeding season (February-March). Ewes were injected with anthelmentic and divided into four groups of similar initial body weight and age and randomly assigned to the treatment groups. One group (60 ewes) without any feed supplementation was used as a control (CTL) (like in farmer traditional practice). The second group (92 ewes) was supplemented with ration A (GNC), the third group (97 ewes) was supplement with ration B (GNC-M) and the fourth group (92 ewes) was supplemented with ration C (RS-M) (Table1). Supplementary feeding practices were imposed on ewes prior to mating (flushing) for 45 days and during late pregnancy (Steaming-up) for 45 days.

Mature (n=18) rams were introduced to all experimental ewes; the ratio of the sexes was 1:20. All rams were divided to 3, 5, 6 and for the first, second, third and fourth group respectively, and they were supplemented with same ration B (GNC-M) at the rate of 600 g/ram every three days. Rams were allowed to mix with the ewes twice daily: at 6:00 and 18:00 h.

Animals were allowed to graze normally under range conditions. Ewes were offered 450 g / head of the ration every three days at the watering periods and the rams 600 g / head for three days, ewes fed in small groups in the watering points in period from 6:00 am to 9:00 am and rams were fed individually in the same period. Ewes were monitored for signs of behaviour estrous and those detected were serviced naturally, those returned to estrous were serviced again, ewes demonstrating were naturally mated twice daily at 6:00 and 18:00 h. The experiment extended to 330 days, including 15 days of adaptation period and feeding supplementation period 90 days.

Data recoding:

Weights of ewes and rams were recorded during mating time. The body condition score (BCS) was determined according to 1 to 5 scale (Khan et al 1992; Russel 1991) and recorded in breeding, mid pregnancy and lambing period.

The lambs were weighed within 6 hours of birth, then at 15, 30, 45, 60, 75, 90, 105 and 120 days of age. Immediately after birth, measurements of body height at withers (HW), body length (BL) and heart girth (HG) of lambs were carried out by a tape according to Owent et al (1977). At lambing, sex and type of birth were recorded then all live lambs were identified by ear tag to follow lamb growth rate every 15 days till 120 days of lamb age.

Table 1. Chemical composition (g/kg DM except for DM which is on air-dry basis) of the supplements
Ingredients	GNC	GNC-M	RS-M
Molasses	−	10	10
Groundnut seed cake	99	89	−
Roselle seeds	−	−	89
Common salt	0.75	0.75	0.75
Salt lick	0.25	0.25	0.25
Nutrient (g/kg DM)
Dry matter	941	940	942
Crude protein	557	504	303
Crude fibre	72	65	144
Crude fat	72	66	212
Ash	52	55	101
NFE	247	310	240
NDF	129	116	244
ADF	95	86	169
ADL	15	13	61
g Ca/ kg DM	0.73	0.74	2.16
g P/ kg DM	5.42	4.87	4.42
Energy density (ME, MJ/kg DM)	12.5	12.4	13.1
In vitro OM digestibility, %	80.9	87.7	62.2
ME metabolizable energy calculated from literature values.

Analytical procedures:

Chemical analysis of the experimental rations was done according to AOAC (1995) and Goering and Van Soest (1991). The ME content was calculated from table values of energy content of the components according to AOAC (1995).

Statistical analyses

Data on ewe weight at birth and weekly body weight changes were analyzed as least square mixed model using supplement age as fixed effects and random error as random effect (Harvey 1990). Birth weights of lambs were analyzed with the same model using supplement, birth type and lamb sex as fixed effect and random effect.

Results

All treatments improved ewes BCS in mid pregnancy and at birth compared with farmer practice (Table 2). Supplements in the mating time and the steamed up pre–lambing decreased ewes body condition change. Ewes in first, second and the third parity number lost more condition in parturition than those of fourth and fifth parity. Ewes with male lambs lost more BCS than those with female lambs, dams with twins lost more BCS compared with those with single births. The interactions among all main effects were not statistically significant and thus results are reported for main effects only.

Table 2. The main effects of supplementation and parity on body condition score (mean± SE) of desert ewes in different physiological states.
		N	BSC at mating	N	BSC at mid pregnancy	N	BSC at lambing
Supplement	GNC	92	2.6±0.04 ^c	80	2.6 ±0.05 ^a	75	2.3±0.07 ^a
	GNC-M	97	2.9±0.04 ^ab	93	2.7±0.05 ^a	80	2.2±0.06 ^a
	RS-M	92	2.9±0.04 ^ab	86	2.6±0.06 ^a	56	2.0±0.08 ^b
	CTL	60	2.8±0.05 ^bc	55	2.5±0.07 ^b	37	2.1±0.10 ^b
Dam parity	Primiparous	76	2.9±0.04 ^a	69	2.7±0.07 ^ab	56	2.1±0.07
	2nd parity	60	2.7±0.05 ^bc	53	2.5±0.06 ^c	35	2.2 ±0.08
	3rd parity	100	2.8 ±0.03 ^b	100	2.6±0.04 ^ab	86	2.0±0.05
	4th parity	69	2.7±0.04 ^c	52	2.5±0.06 ^c	50	2.1±0.07
	5th parity	36	2.7±0.07 ^bc	40	2.6±0.09 ^ab	21	2.3±0.12
	Overall mean	341	2.8±0.01	314	2.6±0.02	248	2.2±0.02
^abc means in the same column, within main categories, bearing different superscripts are different at P<0.05

Supplemented ewes had longer body measurement than non supplemented ewes (Table 3). The supplementation of ewes with RS-M inceased the body measurements of the born lambs. Dam parity had no effect on lamb height at withers (HW), heart girth (HG) and body length (BL). Type of birth as a covariate had no effect on body measurements, but male lambs were longer/higher (HW, HG and BL) than females.

Table 3. Effect of pre-partum supplementary feeding on lamb body measurements (means ± SE)
		Length, cm	Heart girth, cm	Height, cm
	GNC	27.8 ± 0.52^b	35.4 ±0.59^ab	36.3 ± 0.59^a
	GNC-M	27.6 ± 0.47^b	34.8 ±0.53^b	34.2 ± 0.54^b
	RS-M	29.3 ± 0.54^a	36.1 ±0.62^a	36.1 ± 0.62^a
	CTL	27.9 ± 0.84^b	31.9 ±0.96^c	31.8 ± 0.96^c
Dam parity	Primiparous	28.2 ± 0.63	33.4 ±0.72	33.5 ± 0.72
	2^nd Parity	28.2 ± 0.65	35.0 ±0.74	35.1 ± 0.74
	3^rd Parity	27.7 ± 0.46	34.9 ±0.53	34.5 ± 0.53
	4^th Parity	28.3 ± 0.54	34.5 ±0.62	34.5 ± 0.62
	5^th Parity	28.3 ± 0.95	34.9 ±1.08	35.4 ± 0.09
Sex of lamb	Male	28.6 ± 0.56^a	34.8 ±0.64	35.2 ± 0.64^a
Sex of lamb	Female	27.6 ± 0.47^b	34.3 ±0.54	33.9 ± 0.54^b
Birth type	Single	28.4 ± 0.28	34.8 ±0.32	35.0 ± 0.32
Birth type	Twins	27.8 ± 0.69	34.4 ±0.78	34.2 ± 0.78
^abc means in the same column, within main categories, bearing different superscripts are different at P<0.05

Pre-partum supplementation increased lamb birth weight at 75, 90 and 105 days of age compared with farmer practice (control) (Table 4) Dams supplemented with GNC had heavier lambs at 120 days than those supplemented with GNC-M and RS-M. Single lambs were heavier than twins. Male lambs were heavier than female lambs from birth to 120 days of age. The interactions of birth type and sex of lamb were not statistically significant and thus results are reported for main effects only.

Table 4. The effect of supplementation, dam parity, birth type and sex on weights (kg) of the lambs (means ± SE)
Treatment	Birth weight	30 days	60 days	90 days	120 days
Supplementation
GNC	3.6 ± 0.13 ^a	10.5 ± 0.64^a	16.1 ± 0.64^a	22.1 ± 0.73^a	28.3 ± 0.86^a
GNC-M	3.6 ± 0.13^a	10.5 ± 0.65^a	16.5 ± 0.62^a	21.2 ± 0.73^a	26.4 ± 0.87 ^b
RS-M	3.6 ± 0.14^a	10.2 ± 0.67^a	16.8 ± 0.66^a	21.2 ± 0.76^a	26.1 ± 0.84 ^b
CTL	3.0 ± 0.21^b	9.0 ± 0.94^b	13.4 ± 0.95^b	18.8 ± 1.07^b	24.1 ± 0.97^c
Dam parity
Primiparous	3.6 ± 0.15^abc	10.6 ± 0.72	15.8 ± 0.71	21.0 ± 0.80	26.0 ± 0.88
2^nd Parity	3.6 ± 0.17^ac	10.0 ± 0.84	15.7 ± 0.83	20.5 ± 0.94	26.3 ± 1.08
3^rd Parity	3.3 ± 0.12^ab	9.6 ± 0.58	15.8 ± 0.59	20.9 ± 0.69	25.6 ± 0.73
4^th Parity	3.4 ± 0.14^b	10.4 ± 0.71	16.0 ± 0.69	21.0 ± 0.78	26.3 ± 0.88
5^th Parity	3.5 ± 0.24^c	9.7 ± 1.11	15.3 ± 1.10	20.7 ± 1.27	27.7 ± 1.16
Birth type
Single	3.6 ± 0.08^a	11.1 ± 0.36^a	17.3 ± 0.37^a	23.4 ± 0.42^a	27.9 ± 0.40^a
Twin	3.3 ± 0.18^b	9.0 ± 0.86^b	14.1 ± 0.86^b	18.3 ± 1.03^b	24.7 ± 1.19 ^b
Sex of lamb
Male	3.7 ± 0.14^a	10.5 ± 0.70^a	16.7 ± 0.70^a	21.6 ± 0.85^a	27.4 ± 0.94^a
Female	3.3 ± 0.12^b	9.6 ± 0.61^b	14.8 ± 0.60^b	20.0 ± 0.67^b	25.2 ± 0.73 ^b
^abc means in the same column, within main categories, bearing different superscripts are different at P<0.05

In general, ewes' pre-partum supplementation improved lambs daily growth rate up to 90 days (Table 5). Lambs whose dams were supplemented with RS-M tended to have higher growth rates. Supplementation had no effect on lamb growth rate in the interval 90-120 days of age (after weaning).

Table 5. Effect of pre-partum supplementary feeding, birth type and dam parity on lamb growth (mean ±SE) (g ⁄day)
Treatment	0-30 days	30–60 days	60–90 days	90–120 days	0–120 days
Supplementation
GNC	229 ± 16^a	204 ± 22^b	182± 16^a	71 ± 13	127 ± 6^a
GNC-M	225 ± 17^a	204 ± 23^b	173 ± 17^ba	79 ± 14	125 ± 6^a
RS-M	226 ± 18^a	229 ± 25^a	156 ±18^c	70 ± 15	130 ± 7^a
CTL	217 ± 19^b	189 ± 26^c	168 ±19^abc	77 ± 16	116 ± 7^c
Dam parity
Primiparous	240 ± 20	200 ± 28	150 ± 21^c	79 ± 17	127 ± 7
2^nd Parity	222 ± 18	212 ± 26	147 ± 19 ^c	84 ± 15	127 ± 7
3^rd Parity	214 ± 18	211 ± 25	158 ± 18 ^b	72 ± 15	121 ± 7
4^th Parity	226 ± 20	197 ± 30	195 ± 22 ^a	73 ± 18	121 ± 8
5^th Parity	219 ± 20	213 ± 33	198 ± 24 ^a	64 ± 20	125 ± 9
Birth type
Single	240 ± 8 ^a	206 ± 11	195 ± 8^a	72 ± 6	133 ± 3^a
Twin	231 ± 28 ^b	227 ±38	142 ± 8^b	77 ± 3	131 ± 1^b
Sex of lamb
Male	201 ± 20 ^b	176 ± 28^b	174 ± 20^a	79 ± 17	111 ± 7^b
Female	223 ± 10 ^a	229 ± 15^a	163 ± 11^b	77 ± 9^s	135 ± 4^a
^abc means in the same column, within main categories, bearing different superscripts are different at P<0.05

Discussion

In the lambing season, the BCS was reduced in the ewes. During this period the nutritive value of the forage was low and the supplements were not enough for ewe maintenance and fetal growth .Under such conditions, it would be expected that the ewes would have used their body reserves to meet the increased nutrients demand for final fetal growth. These are similar to those of Sairanen et al (2006) and Idris (2001). In farmer practice, ewes in late gestation are grazed on fibrous forage of low nutritive value without any concentrate supplementation.

The results on body measurements of lambs are in disagreement with findings of Atta and El Khidir (2004) who revealed that supplementation had no effect on lamb body measurements. El-Toum (2005) reported that dam parity number had no significant effect on lamb weight at birth. Our study showed that there was significant effect of sex on body measurements of Sudan desert lambs; these findings are in general agreement with those of Methta et al (1995). The birth type had no significant effect on body measurements of Sudan desert lambs which is in agreement with findings of Atta and El Khidir (2004) and Ngere and Aboagye (1981).

Inadequate feed intake during late pregnancy has been found to cause a reduction in birth weight, mammary gland development and milk production (El-Toum 2005). Similar results were obtained by Mellor and Murray (1985). Lambs whose mothers received supplementation in our study had higher body weight than lambs suckled by control ewes; this is in line with findings of Rafiq et al (2006).

In this study male lambs were heavier than females and single lambs recorded heavier weight than twins. These results are in general agreement with those of other research workers: Hassen et al (2002) and Blackburn and Field (1990). On the contrary, El-Toum (2005) indicated that lamb sex had no significant effect on lamb weight at birth, 45, 60 and 75 days of age. Singles were heavier than twins at birth and in the overall age period. Similar results were obtained by Macit et al (2002); Macit et al. (2001); Analla et al (1998) Cloete et al. (2007); Boujenane and kansari 2002), El-Hag et al (2001); El-Toum (2005), and Rastogi (2001).

Ewes' pre-partum supplementation improved lambs growth rate before weaning. Supplementation of pregnant ewes during late gestation may provide adequate energy and protein to support maintenance of animal physiological needs, mammary gland growth, colostrums and milk yield. This result was in line with findings of El-Hag et al (1998), Oeak et al (2005) and El-Toum (2005).

In this study, the higher growth rates in lambs suckled by supplemented ewes is to be expected due to increase in milk production. This is supported by observations of El-Nasr et al (1994) and Rafiq et al (2006). Supplementation had no significant effect on lambs' growth rate after weaning (90-120 days of age). This in line with research of Cook and Fadlalla, (1987) and El-Hag et al (2001). This may be due to the short lactation period of the Sudan desert sheep. At this stage all the lambs depend on the pasture, Sex had no effect on lamb growth rate after weaning Similar results were obtained by El-Hag et al (2001) and Rastogi (2001). Male lambs had higher growth rate only in the interval 60–90 days. These results are in agreement with those of Analla et al (1998), Ali et al (1999) and Boujenane and kansari (2002).

Conclusion and recommendation

Acknowledgements

This study was supported by financial grants from German Academic Exchange Service (DAAD). The authors wish to thank Baballa El-Faki, Abdalla Fadllalmula, Hassan Yassen and G.Khair for their assistance with livestock handling and management, the Nutrition Laboratory staff, Sarsor, G and Hella, M. Institute of Animal Sciences, Humboldt University of Berlin, for nutritional analyses.

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Received 31 October 2010; Accepted 18 November 2010; Published 1 February 2011