Full text of DOI:10.1002/ts.82

Trop. Sci. 2003, 42, 13–21
Seasonal performance of Zebu cattle under two
production systems in South Kordofan, Sudan
FM El-Hag, MMM Ahmed, B Fadlalla, EM Elamin, AS El Wakeel and
MA Mekki
Agricultural Research Corporation, El-Obeid Research Station, PO Box 429, El-Obeid, Sudan
(faisalelhag@hotmail.com)
Abstract In sedentary and transhumant cattle herds calving cows’ weights were significantly
different only at six and 12 months after calving. Cows under the sedentary system had the
highest weights and those calving in the early dry and rainy seasons had the highest calving
weights. Under the sedentary system, cows had the highest milk yields throughout the 12
months after calving and calves had the highest weight gains up to 12 months. Male calves
had higher birth weights and weight gains than females. Production system and calving
season effects on calf mortality were not significant.
Keywords: calving cows, calf performance, milk yield, transhumance, season.
Introduction
Cattle production in Western Sudan is practised extensively under rangeland conditions
(
Hashim and Fadlalla 1989) but with two distinct production systems. The transhumant
system is used by the Messerya and Hawazma tribes (Michael 1991) to overcome limitations
of grazing and water scarcity (El Wakeel and Abu Sabah 1993). The length of the migration
to the north and the time spent there are governed mainly by the rain received (Fadlalla et al.
1
985). In the sedentary production system, farmers remain on the clay-dominated ranges of
the Nuba Mountains throughout the year, with only limited movement (Hashim and Fadlalla
989). The main activity of the sedentary farmers is crop production, whereas livestock
1
raising is the major occupation of the transhumants (El Wakeel and Abu Sabah 1993).
This study concerns the seasonal performance of cattle under sedentary and transhumant
production systems in South Kordofan.
Materials and methods
Records of sedentary and migratory cattle herds of the Kadugli Agricultural Research Station
for a five-year period were used. The station is situated in South Kordofan, which extends
from 10˚00’ to 12˚45’N and 26˚32’ to 32˚00’E, within the savanna zone of the Sahelian belt
(
Figure 1). The average maximum temperature varies between 30 and 35ºC with peaks of
about 39ºC in April, May and June. The rainy season is from July to October, with highest
Accepted 19 February 2002

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FM El-Hag et al.
rainfall in August. Rainfall ranges from 500 mm in the north to over 800 mm in the south
GTZ 1985). A short hot period follows the rainy season, with a cool dry period from
(
December to February. These two periods collectively (October–February) are known as the
early dry season, while the main (late) dry season is from March to June (Hashim and
Fadlalla 1989). Soils range from vertisols, with a clay content of up to 60%, in the south, to
sand dunes locally known as ‘Goz’ in the north (GTZ 1985). The ranges are dominated by
annuals (El-Hag et al. 1997). The main grass species utilized by livestock are Brachiaria
obtusiflora, Echinocloa pyramidalis and Hyperrhenia confinis, with some woody species
such as leaves from Maerua crassfolia and fruits from Faidherbia albida and Dichrostachys
cinerea. In the northern sandy areas the most important grass species for livestock are
Dactyloctenium aegyptium, Echinocloa colonum and Eragrostis tremula with a herbaceous
legume, Zornia glochidiata (El Wakeel and Abu Sabah 1993).
Two herds each of 80 head of Zebu cattle (Bos indicus) were bought in 1982. The animals
were 4–5 years old and each herd had four bulls. One herd was kept in the fenced station farm
(
761 ha), where the soils are dark cracking clays, to simulate the sedentary system of
management. This herd grazed outside the fenced area during the rainy season and was kept
inside during the dry summer period from February to June. The other herd was allowed to
move with transhumants to simulate their system. All animals were ear-tagged and records
were kept of monthly body weights, milk yields, reproductive performance, and calves’ birth
weights, monthly body weights until 12 months and mortalities from 1984 to 1988. All animals
were vaccinated annually against rinderpest, black quarter, haemorrhagic septicemia and
anthrax. Under both systems, lactating cows were milked once at midday. Calves were left with
their dams between midday and the evening, when they returned from grazing, but separated at
night and until milking at midday.
Data were arranged according to three calving seasons; early dry (Oct–Feb), late dry
(
March–June) and rainy (July–Sept) seasons, to study the effects of production system and
calving season on cow and calf performance, and according to calf sex.
Statistical analysis was carried out using least squares mixed models procedures (Harvey
1977). Unequal and disproportionate subclass numbers gave unbalanced factorial designs for
which conventional analysis would not have been applicable. Dam and sire effects, and the
month and year of birth were neglected for the same reasons.
Results and discussion
Production system effects on calving cows’ weights were significant (P < 0.05) at only six
and 12 months after calving (Table 1). Under both systems, cows calve once every two years
and producers practise extended calf nursing. The calving season effect on cows’ weights
was highly significant (P < 0.01) up to eight months after calving. Cows calving during the
early dry and rainy seasons had the highest calving weights (P < 0.01). Maximum weights
were achieved following the rainy season and minimum weights were at the end of the hot
dry summer, and weights increased rapidly at the onset of rains (Saeed et al. 1987). There
was a significant production system × calving season interaction for cows’ weights only at
six months after calving (P < 0.05). Cows calving during the late dry season, under both

Performance of cattle under two production systems
15
Obeid
kilometres
Figure 1. Migration routes of transhumant tribes in South Kordofan, Sudan.
systems, had higher six-month weights than those calving during the early dry season under
the sedentary system.
Least square estimates for mean calving cow weight change were significantly (P < 0.01)
affected by both production system and calving season, but no significant (P > 0.05) interaction
main effect was found (Table 2). Weight losses during the first six months after calving were
more pronounced in the sedentary system than in transhumance (P < 0.01). However, cows in

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FM El-Hag et al.
the sedentary system had a 12-month weight gain of about 0.6 kg/cow compared to a loss of
2.8 kg in the transhumance, due presumably to the limited animal movement under the
1
sedentary system (Fadlalla et al. 1985).
Calving season had a highly significant (P < 0.01) effect on calving cows’ weight change.
Only cows that calved during the late dry season had a 12-month weight gain, whereas those
Table 1. Least squares means for calving cows’ weights as affected by production system and calving season
Weight (kg) at months from calving
Variable
N
0
1
3
6
8
12
Overall mean
Production system
Sedentary
Transhumant
verage SE ±
P
80
255.8
246.6
246.2
237.7
241.7
249.7
44
36
259.1
251.7
5.64
0.3607
245.9
247.5
4.87
0.8132
241.7
251.7
5.03
0.1614
229.9a
247.3b
5.28
240.7
242.9
5.66
258.5a
238.9b
5.99
0.0231
0.7832
0.0236
Calving season
Early dry
Late dry
Rainy season
Average SE ±
P
28
27
25
268.9a
246.5a
234.5a
216.0c
257.1d
241.1d
7.88
238.9ab
257.9a
227.4b
8.47
264.9c
244.2cd
238.7d
8.95
234.3b
267.4a
8.43
232.1a
262.3b
7.27
241.7a
264.1b
7.51
0.0015
0.0029
0.0063
0.0005
0.0104
0.1305
System × Season
Average SE ±
P
18.24
0.7765
15.74
0.8170
16.25
0.3256
17.05
0.0491
18.31
0.3878
19.37
0.8705
Values in the same column with different letters are significantly different at P < 0.01 and/or P < 0.05.
Table 2. Least squares estimates for cows weight change (kg) as affected by production system and calving season
Months after calving
Variable
N
0–1
0–3
3–6
6–8
4.0
8–12
8.3
Overall mean
Production system
Sedentary
Transhumant
Average SE ±
P
80
–9.2
–7.2
–9.7
44
36
–13.2
-4.3
3.47
–17.4
0.0
4.38
–14.0
-4.5
3.55
0.0618
10.8
-4.3
2.64
0.0001
18.9
-4.0
4.56
0.0005
0.0728
0.0005
Calving season
Early dry
Late dry
Rainy season
Average SE ±
P
28
27
25
–22.3a
–2.2b
–5.1c
5.18
–-34.3a
7.4b
–18.5a
22.9a
0.8b
–13.7c
3.94
25.5a
–13.7b
11.0c
6.81
0.0007
15.7b
–23.0c
5.31
3.3c
6.54
0.0000
0.0030
0.0000
0.0000
System × Season
Average SE±
P
11.2
0.5994
14.16
0.9782
11.49
0.1292
8.53
0.1314
14.74
0.2576
Values under the same variable and in the same column with different letters are significantly different at P < 0.01.

Performance of cattle under two production systems
17
calving in the early dry and especially the rainy seasons lost weight. In many range areas or
during periods of feed scarcity, lactating and breeding females frequently lose weight during
part of the year (NRC 1984). Late dry season calvers have the good grazing resources of the
rainy season (El-Hag et al. 1997), whereas those calving during rainy or early dry seasons face
a long period with low-quality feed resources.
Complete 12-month milk records were obtained for 69 cows only. Production system had
no effect on milk yield during the first two months or the fourth month of lactation (Table 3).
Cows under the sedentary system had the highest milk yields throughout the 12 months
following calving. The effort spent in grazing and long-distance movements are likely to cause
lower milk yields in transhumant cattle.
The effect of calving season on milk yield was significant (P < 0.01) during the first six
months of lactation (Table 3). Cows calving during late dry and rainy seasons had higher
(
P < 0.05) milk yields during the first three months of lactation than early dry season
calvers. Late dry season calving cows exceeded the other two categories in monthly milk
yield throughout the first six months of lactation. However, the total 12-month milk
production for cows calving during early dry, late dry and rainy seasons were 405, 431 and
3
55 kg, respectively. There was a significant production system × calving season interaction
(
P < 0.05) for monthly milk yield only in the fifth month. Cows calving during the late dry
season under the sedentary system had higher fifth month milk yield than those in the
transhumant system.
Data for calf growth up to 12 months of age were available for 112 calves only (59
males and 53 females), but the production system had no effect (P > 0.05) on calf weights
(
Table 4). Season of birth had a significant effect (P < 0.08) on weight at birth and at six and
eight months (P < 0.01). Calves born during the rainy season had the highest birth weights,
whereas those born in the late dry season had the highest weight from six to 12 months.
Saeed et al. (1987) found that season of calving had a significant effect on weight at birth
but not subsequently, but Tawonezvi (1989) reported that birth weight increased as the
calving season advanced and calves born later maintained their growth advantage until 18
months. The production system × season of birth interaction effect on calf weight was
significant (P < 0.05) at 12 months only. Calves born under the sedentary system in the
early dry season or under the transhumant system during the early dry or rainy seasons had
the lowest 12-month weights.
Male calves had relatively (P > 0.05) higher weights from birth up to 12 months than
females. This disagrees with Kabuga and Agyemang (1984) who found that sex of calf signifi-
cantly influenced only birth weight, although Woodward et al. (1989) reported that males had
the greater growth potential. Calf sex × production system main effect was significant
(
(
P < 0.05) for birth weight only. Production system effect on calf weight gain was significant
P < 0.05) from six to eight months of age (Table 5). Calves born under the sedentary system
had higher weight gain from six to eight months and higher total weight gain up to 12 months
of age (P < 0.09). Mrode (1988) found that there were no significant differences between
animals maintained in the semi-humid southern Nigeria than the semi-arid north.
Calf weight gain was significantly (P < 0.01) affected by season of birth from three to six
months of age and for 12-month gain. Early dry and rainy season calves had the highest weight

1
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FM El-Hag et al.

Performance of cattle under two production systems
19
Table 4. Least squares estimates for calf weight (kg) at different ages as affected by production system, season of
birth and calf sex
Weight at age (months)
Variable
N
Birth
17.9
1
3
6
8
12
Overall mean
Production system
Sedentary
Transhumant
Average SE ±
P
112
29.4
42.0
59.9
69.4
72.4
58
54
18.1
17.6
0.41
0.4267
29.5
29.4
0.78
0.9753
42.7
41.2
1.36
0.4560
60.9
58.9
1.83
0.4738
70.1
68.7
2.17
0.6871
85.2
79.3
2.60
0.1226
Calving season
Early dry
Late dry
Rainy season
Average SE ±
P
30
43
39
17.4
17.4
18.8
0.62
28.6
28.9
30.7
1.18
0.2217
38.8
42.3
44.0
2.07
0.1101
51.1
65.8
60.3
2.77
0.0002
61.6
76.6
67.6
3.30
0.0011
80.3
83.7
82.5
3.94
0.7829
0.0763
System × Season
Average SE ±
P
1.46
0.1669
2.74
0.6918
4.82
0.8973
6.49
0.1759
7.70
0.0526
9.19
0.0177
Calf sex
Males
Females
Average SE ±
P
59
53
18.3
17.3
0.41
0.1070
29.6
29.3
0.79
42.6
41.3
1.39
61.3
58.4
2.06
70.4
68.4
2.40
84.5
80.0
2.67
0.7602
0.5547
0.3685
0.5847
0.3213
System × Sex:
Average SE ±
P
0.82
0.0124
1.58
0.5949
2.80
0.7593
4.15
0.8953
4.84
0.6433
5.39
0.2663
gains, while late dry season had the lowest (Table 5). Calves born during the wet summer had
significantly higher growth from four to six months than other calves in other seasons (Saeed et
al. 1987). No significant differences (P > 0.05) were found between production systems or
seasons of birth on calf mortality. Calf mortality rates were 15.1 and 25.8% for sedentary and
transhumant systems respectively and the rates were 23.9, 12.1 and 25.6% for early dry, late
dry and rainy seasons. Higher calf mortality in the transhumant system could be because long-
distance migration stresses calves, and the higher mortality in the rainy season could be due to
exposure to direct rain and pneumonia. Saeed et al. (1987) found an overall calf mortality of
16.6% up to one year of age for kenana calves in central Sudan and more calves born in the wet
season died than those born in the cool winter or hot summer. Calf sex, and production system
×
sex interaction effects on calf weight change were not significant (P > 0.05).
Conclusions
Under the sedentary system cows produced more milk and calf performance was better than
under transhumance.

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FM El-Hag et al.
Table 5. Least squares estimates for calf average body weight gain (kg), and mortality rate (%), as affected by
production system, season of birth and sex
Calf body weight gain (kg) at different periods (months)
Variable
N
Mortality
0–1
0–3
3–6
6–8
0–12
13.9
Overall mean
Production system
Sedentary
Transhumant
Average SE±
P
112
26.1 (20.5)
29.0
23.4
17.1
11.3
59
53
22.3 (15.1)
29.9 (25.8)
3.46 (4.86)
0.326 (0.333)
29.1
29.0
0.21
0.5910
23.6
23.1
0.40
0.8039
17.4
16.8
0.40
0.7389
9.8
13.0
0.35
0.0465
16.0
11.5
0.57
0.0834
Calving season
Early dry
Late dry
Rainy season
Average SE±
P
29
40
43
27.7 (23.9)
20.3 (12.1)
30.4 (25.6)
4.72 (6.60)
10.8
11.8
10.6
1.04
0.6015
21.4
23.3
24.9
1.94
0.2733
11.6
21.7
16.2
1.92
0.0000
12.1
12.2
9.6
1.71
0.2093
18.3
7.8
17.4
2.78
0.0041
System × Season
Average SE±
P
9.99
0.3367
2.40
0.5756
4.50
0.7369
4.44
0.3330
3.97
0.8501
6.43
0.0444
Calf sex
Males
Females
Average SE±
P
58
54
26.4 (19.8)
27.6 (21.2)
2.45 (4.12)
11.3
11.2
0.68
23.5
23.1
1.27
17.3
16.9
1.39
10.4
12.3
1.15
14.4
13.4
1.96
0.6975
0.9380
0.9724
0.9154
0.3390
System × Sex
Average SE±
P
1.37
0.4119
2.59
0.6855
2.83
0.9455
2.27
0.4468
3.90
0.1138
Mortality rates are Arc sign transformed and numbers in parentheses are actual rates.
Acknowledgements
We thank Messrs Mohamed S Hamid, Hamid Elraiah, Abdalla Fadlalmulla and Ibrahim
Gaboosh for their help in data collection.
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