4.1 Evaluation approach
4.2 Productivity of N'Dama and West African Shorthorn cattle groups
4.3 Productivity of Zebu x humpless cattle groups
4.4 Comparison with Zebu cattle
4.5 Productivity of sheep
4.6 Productivity of goats
4.7 Conclusions
A major problem in using animal production data from Africa is how to make maximum use of results produced in isolation. The Report of the first FAO Expert Consultation on Research on Trypanotolerance and Breeding of Trypanotolerant Animals (FAO, 1976) concluded that, although considerable work was being undertaken on the productivities of trypanotolerant cattle types, little comparative information had become available. For this reason it was stressed that the emphasis should be on comparisons between animal breeds or types in given environments, rather than on measures of absolute value only. However, to build up accurate animal production information even in isolation is expensive and takes time. For this reason, gathering, evaluating and comparing those data which have been produced are of utmost importance.
For each country discussed in Volume 2, estimates of the main production traits required to build up a productivity index are given wherever sufficient information is available. The environmental and management conditions under which these basic productivity levels were achieved are also indicated. In the case of cattle, the traits evaluated are reproductive performance, cow and calf viability, milk production, growth and cow body weight. These have then been used to build up an index of the total weight of one-year-old calf plus the liveweight equivalent of milk produced, both per cow per year and finally per 100 kg of cow maintained per year. The steps in the calculations are laid out in Table 4.1.
This final index is the most meaningful way to compare the actual productivities of the wide range of cattle types found in the study area, given the level of information available. Its merit lies in relating all the more important production traits back to the actual weight of breeding cows that has to be supported, which is closely connected with maintenance costs. The traits and productivity indices have been derived for two basic management systems, in villages and on ranches or stations, and for four levels of trypanosomiasis risk designated as zero, low, medium and high. As trypanotolerance is not an absolute but a relative characteristic, liable to break down if the level of trypanosome infection is high enough, it is important from a land-use and development point of view to know the likely level of trypanosome infection in livestock to be brought into a given area. This level is a function of several factors, such as density of tsetse infestation, species of tsetse present (some species are more effective transmitters than others), infection rate in the flies, density of all potential hosts and climatic conditions. The role of other biting flies which are capable of transmitting infection must also be considered. For this reason, the term trypanosomiasis risk is used to describe all the factors which influence the level of trypanosome infection, rather than tsetse challenge or tsetse risk which were commonly used in the past. The four levels of trypanosomiasis risk designated have been defined rather arbitrarily, as very little actual information on the contributing factors is available.
Table 4.1. Steps in the calculation of productivity indices.
|
Parameter |
Code |
Calculation |
|
Cow mortality during year (%) |
A |
|
|
Calving percentage (%) |
B |
|
|
Calf mortality to 1 year (%) |
C |
|
|
Percent of calves reaching 1 year (%) |
D |
B(100 - C) ÷ 100 |
|
Calf weight at 1 year (kg) |
E |
|
|
Annual milked-out lactation yield (kg) |
F |
|
|
Percent of cows completing a lactation (%) |
G |
100 - (C ÷ 2)a |
|
Total liveweight equivalent of milked-out yield (kg) |
H |
F(G ÷ 100) ÷ 9b |
|
Total weight of 1-year-old calf produced per cow (kg) |
I |
E(D ÷ 100) |
|
Weight of 1-year-old calf plus liveweight equivalent of milk produced per cow maintained (kg) |
J |
(I + H) ÷ [[100 - (A÷2)] ÷ 100]c |
|
Average cow body weight (kg) |
K |
|
|
Weight of 1-year-old calf plus liveweight equivalent of milk produced per 100 kg of cow maintained annually (kg) |
|
J x 100 + K |
a. A cow whose calf dies during the lactation period is considered on average to have actually produced milk during half the period.b. Conversion factors constructed from Drewry et al (1959).
c. Cows dying during the year are considered on average to have been maintained for half a year.
Source: Compiled by authors.
Production information is particularly scarce for trypanotolerant sheep and goats. However, similar production indices have been built up wherever possible, based on weight of 5-month-old progeny produced per 10 kg of breeding female maintained per year.
The synthesis and comparison of the data available on cattle are carried out in three steps. First, all the situations in each country are combined where productivities of the two main trypanotolerant groups, N'Dama and West African Shorthorn, are available, to compare the two groups and illustrate the effects of management systems and trypanosomiasis risk. Next, the few situations are considered where productivity data on crosses between Zebu and humpless cattle are available, and finally the equally few situations are examined where productivity figures on Zebu cattle in the study zone have been obtained. In the case of data on sheep and goats, all available production data are combined and summarized.
Thirty individual situations in 12 countries were identified where production indices under known management systems and estimated trypanosomiasis risk could be calculated. These are presented in Table 4.2.
Table 4.2 Distribution of 30 trypanotolerant cattle production situations by country, breed group, management system and trypanosomiasis risk.
|
Breed group |
Management system |
Trypanosomiasis Risk |
|||
|
Zero |
Low |
Medium |
High |
||
|
N'Dama |
village |
|
4, 5, 7, 10 |
2, 2, 6 |
1, 4 |
|
|
ranch/station |
3, 4 |
1, 1, 2, 5, 11, 12 |
2, 3 |
1, 6 |
|
Shorthorn |
village |
|
3 |
1, 2, 2, 8 |
|
|
|
ranch/station |
3 |
2, 3 |
9 |
|
1 = Zaire, 2 = Ivory Coast, 3 = Nigeria, 4 = Gambia, 5 = Senegal, 6 = Mali, 7 = Guinea, 8 = Central African Republic, 9 = Benin, 10 = Guinea Bissau, 11 = Sierra Leone and 12 = Togo.
Source: Compiled by authors.
The traits examined in these 30 situations were calving percentage, calf viability to one year, calf weight at one year, mature cow weight, productivity index per cow per year, and productivity index per 100 kg of cow maintained per year. Least squares analyses were carried out on all traits separately (Harvey, 1960), fitting constants for breed group, management system, trypanosomiasis risk and country. The least squares means for breed group, production system and level of trypanosomiasis risk are presented in Table 4.3 and the analyses of variance in Table 4.4. As the data on which these analyses are based were very limited, it was not possible to examine the interactions which are likely to exist among the variables.
Table 4.3 indicates no significant difference between N'Dama and West African Shorthorn for the major index of productivity per 100 kg of cow maintained. The actual values are 28.7 kg per annum for N'Dama and 28.3 kg for Shorthorn. The only significant differences in individual traits leading to this index are weight of 1-year-old calf and weight of mature cow, with the N'Dama group very much heavier in each case. The higher calf weight leads to a higher index per cow for the N'Dama, but the higher mature cow weight lowers the index per 100 kg of cow maintained to a level similar to that of the Shorthorn.
The effect of village management, compared with management on ranches or stations, is clearly illustrated in Table 4.3. Approximately 14% lower calving rates, 15% lower viability and 20% lower calf weight at one year result in a 38% lower productivity index per cow from the village compared with the ranch or station. Six percent lower mature cow weights lead to a 30% lower productivity index per 100 kg of cow maintained.
An indication of the effect of the level of trypanosomiasis risk is also illustrated in Table 4.3. Zero risk is confounded with very intensive feeding and management, thus only low, medium and high risk can be directly compared. When productivity levels under medium trypanosomiasis risk are compared with those achieved under low risk, calving is 18% lower, calf viability 5% lower and calf weight 1% lower, resulting in a 30% lower productivity index per cow and a 27% lower productivity index per 100 kg of cow maintained per year. Similarly, when productivity levels under high trypanosomiasis risk are compared with those achieved under low risk, calving is 7% lower, calf viability 17% lower and calf weight 5% lower, resulting in a 56% lower productivity index per cow and a 41% lower productivity index per 100 kg of cow maintained per year.
The data presented in Volume 2 show clearly the tremendous range of productivity levels occurring among both the N'Dama and Shorthorn under different production systems and levels of trypanosomiasis risk. In both breed groups the range extends from about 15 kg of 1-year-old calf plus liveweight equivalent of milk produced per 100 kg of cow maintained per year under village conditions in a high trypanosomiasis risk area to about 50 kg under improved ranch or station conditions and low trypanosomiasis risk.
Table 4.3. Least squares means for production traits of trypanotolerant cattle groups under different management systems and levels of trypanosomiasis risk.
|
Variable |
Number |
Calving % |
Calf viability % |
Calf weight (kg) |
Cow weight (kg) |
Index/Cow (kg) |
Index/100 kg cow(kg) |
|
Overall mean |
30 |
69.1 |
78.4 |
96.4 |
205 |
58.7 |
28.5 |
|
Breed |
|
|
|
|
|
|
|
|
N'Dama |
21 |
70.1 |
79.9 |
113.7a |
248a |
72.3a |
28.7 |
|
Shorthorn |
9 |
68.1 |
76.9 |
79.1b |
162b |
45.1b |
28.3 |
|
System |
|
|
|
|
|
|
|
|
Ranch/station |
16 |
76.4a |
85.8a |
107.1a |
212 |
72.3a |
33.7a |
|
Village |
14 |
61.8b |
71.0b |
85.7b |
198 |
45.1b |
23.3b |
|
Trypanosomiasis risk |
|
|
|
|
|
|
|
|
Zero* |
3 |
92.4a |
81.5 |
97.7 |
216 |
89.8a |
40.1a |
|
Low |
13 |
73.1b |
84.6 |
98.1 |
212 |
68.2b |
31.9b |
|
Medium |
10 |
54.8c |
79.7 |
96.7 |
200 |
47.2c |
23.2c |
|
High |
4 |
56.1c |
67.8 |
93.1 |
192 |
29.6d |
18.8c |
* Zero trypanosomiasis risk is confounded with very high levels of feeding and management.
a - d. Any values within a subgroup with different subscripts are significantly different (P < 0.01).
Source: Data from situations listed in Table 4.2.
Table 4.4. Analyses of variance for production traits of trypanotolerant cattle groups.
|
Source of variation |
d. f. |
Mean squares |
|||||
|
Calving % |
Calf viability |
Calf wt at 1 year |
Cow mature wt |
Index/cow |
Index/100 kg cow |
||
|
Breed group |
1 |
14 |
37 |
4647 |
28349** |
2955** |
2 |
|
Management system |
1 |
919** |
944** |
1989** |
845 |
3131** |
448** |
|
Trypanosomiasis challenge |
3 |
698** |
190 |
17 |
344 |
1601** |
213** |
|
Country |
8a |
279 |
113 |
305** |
704* |
630* |
65** |
|
Residual |
16 |
110 |
79 |
89 |
237 |
100 |
15 |
* Significant at P < 0.05.
** Significant at P < 0.01.
a. Data from Guinea, Guinea Bissau and Sierra Leone were grouped under one region, Togo and Benin under another.Source: Data from situations indicated in Table 4.2.
Two locations in Nigeria and Benin were identified where -productivity indices for Keteku and Borgou cattle could he derived and compared with N'Dama and Shorthorn respectively. Management in both cases was under ranch conditions and trypanosomiasis risk was medium with no prophylactic treatment against trypanosomiasis. Production levels and indices are given in Table 4.5. In neither case was there any indication that the productivity of the Zebu x trypanotolerant crossbreds surpassed that of the trypanotolerant group.
Table 4.5. Productivity of trypanotolerant and Zebu x trypanotolerant crossbred cattle on two ranches under medium trypanosomiasis challenge.
|
Parameter |
Nigeria |
Benin |
||
|
N'Dama |
Keteku |
Shorthorn |
Borgou |
|
|
Cow viability (%) |
99 |
99 |
95 |
88 |
|
Calving percentage |
58 |
57 |
58 |
33 |
|
Calf viability to 1 year (%) |
95 |
95 |
76 |
72 |
|
Calf weight at 1 year (kg) |
156 |
142 |
85 |
119 |
|
Productivity indexa per cow per year (kg) |
86.4 |
77.3 |
38.4 |
30.1 |
|
Cow weight (kg) |
260 |
260 |
152 |
226 |
|
Productivity indexa per 100 kg cow maintained per year (kg) |
32.2 |
29.7 |
25.3 |
13.3 |
a. Total weight of one-year-old calf plus liveweight equivalent of milk produced.
Source: Based on productivity figures presented in Volume 2.
Three locations, in Nigeria, Ivory Coast and Central African Republic, were identified where productivity of Zebus under known management conditions and trypanosomiasis risk could be compared with that of trypanotolerant types. Additionally, one location was identified in Mali where preliminary production figures for Zebu and N'Dama under feedlot conditions were available. Production levels and indices are shown in Table 4. 6 and feedlot data in Tables 4.7 and 4.8.
Table 4.6. Productivity of trypanotolerant and Zebu cattle in three locations under zero, light and medium trypanosomiasis risk.
|
Parameter |
Nigeria/zero risk/station management |
Ivory Coast/low risk/village management |
Central African Republic/medium risk/village management |
||||
|
N'Dama |
Shorthorn |
Zebu |
Shorthorn |
Zebu |
Shorthorn |
Zebu |
|
|
Cow viability (%) |
100 |
100 |
100 |
98 |
96 |
96 |
95 |
|
Calving percentage |
100 |
96 |
91 |
70 |
72 |
68 |
63 |
|
Calf viability to 1 year (%) |
97 |
95 |
100 |
55 |
60 |
80 |
65 |
|
Calf weight at 1 yr (kg) |
131 |
101 |
200 |
75 |
90 |
90 |
120 |
|
Annual milked out yield (kg) |
- |
- |
- |
70 |
144 |
- |
71 |
|
Productivity indexa per cow per year (kg) |
128 |
92 |
181 |
36.9 |
55.4 |
50.0 |
58.1 |
|
Cow weight (kg) |
266 |
183 |
343 |
200 |
270 |
190 |
320 |
|
Productivity indexa per 100 kg cow maintained per year (kg) |
48.1 |
50.2 |
52.8 |
18.5 |
20.5 |
26.3 |
18.2 |
a. Total weight of one-year-old calf plus liveweight equivalent of milk produced.
Source: Based on productivity figures presented in Volume 2.
Table 4.6 indicates virtually no difference between the trypanotolerant and Zebu groups for the major index of productivity per 100 kg of cow maintained per year: the trypanotolerant groups were on average 0.3 kg or 1% lower. The higher weight of 1-year-old calf for the Zebu led to a 40% higher Zebu productivity index per cow, but the correspondingly higher mature cow weight resulted in very similar group productivity indices per 100 kg of cow maintained. Similarly, Tables 4.7 and 4.8 showing feedlot performances indicate that while the Zebu was superior to the N'Dama in terms of absolute daily liveweight gain, the daily liveweight gains per 100 kg body weight maintained were virtually identical.
Table 4.7. Feedlot performance data for 49 Zebu and 49 N'Dama over a 65-day period.
|
Parameter |
Breed |
|
|
Zebu |
N'Dama |
|
|
Daily liveweight gain (g) |
667 |
542 |
|
Mean body weight (kg) |
223 |
172 |
|
Daily liveweight gain/100 kg body weight (g) |
300 |
311 |
Source: Data from Mali, Service de l'Elevage.
Table 4.8. Analysis of variance for feedlot performance.
|
Source of variation |
d.f. |
Mean squares (x 10-2) |
||
|
Daily liveweight gain |
Mean body weight |
Daily liveweight gain/100 kg body weight |
||
|
Between feedlots |
1 |
3960** |
70* |
1760** |
|
Between breeds |
1 |
3810* |
630** |
30 |
|
Residual |
95 |
669 |
7 |
61 |
* Significant at P < 0.05.
** Significant at P < 0.01.
Source: Calculated by authors.
The data presented in the three tables do not suggest that Zebu are superior to trypanotolerant cattle in any of these situations, even though they are all characterized by relatively low trypanosomiasis risk.
Table 4.9 summarizes the nine situations for which productivity data on trypanotolerant sheep were available, as described in Volume 2.
Table 4.9. Means and standard errors for production traits of trypanotolerant sheep in nine situations under a variety of management systems and levels of trypanosomiasis risk.
|
Parameter |
Mean |
Standard Error |
|
Ewe viability (%) |
86.0 |
6.2 |
|
Lambing percentage |
179.0 |
4.4 |
|
Lamb viability to 5 months (%) |
68.0 |
4.9 |
|
Lamb weight at 5 months (kg) |
11.5 |
0.4 |
|
Productivity indexa per ewe (kg) |
15,1 |
1.1 |
|
Ewe weight (kg) |
23.6 |
0.4 |
|
Productivity indexa per 10 kg ewe maintained per year (kg) |
6.4 |
0.4 |
a. Total weight of 5-month-old lamb produced per year.
Source: Based on productivity figures presented in Volume 2.
The nine situations summarized in Table 4.9 are spread over six countries. The data are not adequate to allow the effects of management systems and levels of trypanosomiasis risk to be estimated, as was possible with trypanotolerant cattle. From these data, the best estimate of productivity of trypanotolerant sheep for the study area as a whole is 6.4 kg of 5-month-old lamb produced per 10 kg of ewe maintained per year.
Table 4.10 summarizes the three situations for which productivity data on trypanotolerant goats were available, as described in Volume 2. The three situations summarized in this table are in three different countries. As with sheep, there are too few data to allow any estimates of the effects of management or levels of trypanosomiasis risk. From these data the best estimate of the productivity of trypanotolerant goats in the study area as a whole is 6.9 kg of 5-month-old kid produced per 10 kg of adult female maintained per year.
Table 4.10. Means and standard errors for production traits of trypanotolerant goats in three situations under village conditions and medium trypanosomiasis risk.
|
Parameter |
Mean |
Standard Error |
|
Adult female viability (%) |
88 |
3.4 |
|
Kidding percentage |
224 |
23.4 |
|
Kid viability to 5 months (%) |
77 |
0.6 |
|
Kid weight at 5 months (kg) |
7.5 |
0 |
|
Productivity indexa per adult female (kg) |
14.8 |
1.1 |
|
Adult female weight (kg) |
21.3 |
1.9 |
|
Productivity indexa per 10 kg adult female maintained per year (kg) |
6.9 |
0.4 |
a. Total weight of 5-month-old kid produced per year.
Source: Based on productivity figures presented in Volume 2.
All the productivity data on N'Dama and Shorthorn cattle groups and their comparisons with Zebu x humpless and Zebu groups identified in the study zone have been evaluated. These indices make it possible to compare more objectively the productivity of trypanotolerant cattle with that of indigenous groups in the tsetse-free areas of Africa. It has only been possible to build up a very rough estimate of the productivity of trypanotolerant sheep and goats.
On the basis of the index of total weight of one-year-old calf plus the liveweight equivalent of milk produced per 100 kg of cow maintained per year, no significant differences are found between the two main trypanotolerant groups, the N'Dama and the Shorthorn. The mean value for troth groups combined is 28.5 kg. No indication has been found from the limited data available that either the Zebu x humpless crossbreeds or the Zebu are significantly more productive than the two trypanotolerant groups in the study zone. However, Zebu and Zebu x humpless types are not often found alongside humpless cattle, and thus field-level comparative data are scarce. The limited data on Zebu and Zebu crosses generally relate to favourable situations (i. e. light trypanosomiasis risk and a high level of veterinary care) and are not representative of the situation in the study area as a whole. General impressions of experience with the introduction of Zebu in these areas since the beginning of the century and the generally poor condition of the Zebu observed suggest that the trypanotolerant groups could have even greater -potential production advantages over the Zebu than the limited available data indicate.
Little objective information has been found on the draught and milking capabilities of the trypanotolerant breeds, though they are widely used as draught animals in most of the study area. While the importance of crossbreeding to produce larger draught animals is often mentioned, in practice the choice of a draught animal generally depends on good condition and lack of disease problems, rather than on size and weight alone. It has been observed in several regions that N'Dama, and even the smaller West African Shorthorn, are preferred as draught animals over the larger breeds, and the natural amenability to training of trypanotolerant oxen is often stressed.
It has been mentioned on several occasions that Zebu and crossbred cattle produce more milk than trypanotolerant cattle even under traditional husbandry conditions. However, objective information is not available to compare milk production of the different breeds, taking account of important parameters such as body weight, reproductive performance and viability.
