Introduction
Predicted performance of F1 crosses between Friesian and local cattle
Cow body size
Comparisons among breeds at government units and on smallholder farms
In this section dairy production characters as reported for the smallholder herds and various government dairy units are compared, bearing in mind the differences in management regimes at the various units. The comparisons are across different breed compositions and across different geographical areas, and hence across different rainfall and feed-availability zones. The expected performance of F1 crossbred cows is considered first, using estimated figures reported elsewhere in this report and some assumptions.
The average performance of F1 crossbred cows for a given character can be predicted if the mid-parental mean for that character and the average percent heterosis are known. The predicted performance is calculated as 0.5 (P1 + P2) + (% heterosis x 0.5(P1 + P2), where P1 and P2 are the average performances of the parents.
The estimated average performance of purebred Friesians at Mikolongwe, and rough estimates for the 'off-type' cows at Chizombezi and for Malawi Zebu cows in terms of lactation milk yield, lactation length, yield per lactation day and calving interval are shown in Table 37.
The approximate percentages of heterosis for lactation milk yield, lactation length, yield per lactation day and calving interval, derived from figures reported by McDowell (1983), are shown in Table 38, with the predicted and actual performance for F1 cows, and the differences between predicted and actual values.
Table 37. Average performance of Friesian and local cattle for four milk production parameters.
|
Trait |
Type of cattle |
||
|
Pure Friesian |
Off- type¹ |
Malawi Zebu² |
|
|
Lactation milk yield (kg) |
3 500 |
1 000 |
450 |
|
Lactation length (days) |
350 |
250 |
180 |
|
Yield/day (kg) |
10.0 |
4.0 |
2.5 |
|
Calving interval (days) |
480 |
530 |
600 |
¹'Off-type' cattle formed from Sussex, Brahman-type and Africander-cross cattle.
² Figures on Malawi Zebu based on observations by extension staff.
Table 38. Predicted and actual production of Friesians and local F1 crosses in Malawi.
|
Trait |
F1 performance |
||||||
|
Approximate % heterosis |
1/2 Friesian- 1/2 off-type |
1/2 Friesian -1/2 Malawi Zebu |
|||||
|
Predicted |
Actual |
Difference |
Predicted |
Actual |
Difference |
||
|
Total milk yield (kg/cow) |
6.0 |
2 380 |
1 950 |
430 |
2 090 |
1 680 |
410 |
|
Lactation length (days) |
6.0 |
320 |
379 |
-59 |
283 |
307 |
-24 |
|
Yield/day (kg) |
7.0 |
7.5 |
5.4 |
2.1 |
6.7 |
5.6 |
1 .1 |
|
Calving interval (days) |
9.0 |
460 |
488 |
-28 |
490 |
407 |
83 |
The actual production of F1 crosses (1/2 Friesian 1/2 'off-type') on smallholder farms was about 20% less than the predicted performance, and lactation length was longer than expected, mainly because some of the cows had difficulty conceiving (Table 38). Calving interval was only about 6% longer than the predicted value. Figures for the 1/2 Friesian- 1/2 Malawi Zebu at Chitedze Research Station followed the same trends. These observations are, however, subject to the appropriateness of the heterosis percentages used for the various traits. If lower values for heterosis were used, the differences between the predicted and actual values would be smaller. The figures presented in Table 37 and 38 suggest that, theoretically, the F1 crossbred cows both on the smallholder farms and at the stations are performing at close to the level that could be expected from their genetic make-up. However, as shown earlier, the productivity of the animals has been declining, and year-to-year analysis would reveal a wider gap between predicted and actual performances.
No accurate data on mature cow body weight are available from any of the livestock centres in Malawi because none of the stations have weigh-bridges. Mature body weights were taken using a weigh-band, which is adequate for the purpose of administering drugs, such as during drenching, but is of no use in evaluating breed productivity.
Mature body weights, obtained using a weigh-band, of a sample of 1/2-, 3/4- and 7/8-Friesian cows on smallholder farms were 400, 410 and 500 kg, respectively. The corresponding figures at Tuchila rearing centre were 432, 400 and 490 kg. No figures were available for Friesian-Malawi Zebu crossbred cows, but visual observations indicate that they are smaller and lighter than Friesian-'off-type' crosses.
Performance of 7/8 Friesian -1/8 Malawi Zebu and Friesian cows at Chitedze and Bwemba
Performance of Friesian - Malawi Zebu crosses and Friesian 'off-type' crosses
Performance of Friesian cattle at Mikolongwe, Bwemba and Chitedze
Milk yield per lactation day and annual yield per cow were used in comparisons among breeds at government stations and on smallholder farms. The two traits were chosen because milk yield per lactation day overcomes the problem of differences in milk yield over various lactation lengths, while annual yield per cow takes into account different calving intervals.
Chitedze and Bwemba are about 10 km apart, and are both government units. Both have 7/8 Friesian-1/8 Malawi Zebu and pure-Friesian cows. The aim of the comparison was to determine how the different objectives of the two units-Chitedze is a research station and Bwemba is a multiplication centre - and hence possible differences in their management practices, might have influenced the performance of the two breeds of cattle.
Age at first calving for the 7/8 Friesian-1/8 Malawi Zebus was 37 months and that of pure Friesians was 36.9 months at Bwemba. The corresponding figures at Chitedze were 45.8 and 45.4 months. Thus there was no difference between the two breeds for age at first calving, but heifers at Bwemba calved at 8 months younger than the heifers at Chitedze. Yields per lactation day for the 7/8 Friesians and the pure Friesians were 9.4 and 9.5 kg, respectively, at Bwemba, and 7.3 and 7.4 kg, respectively, at Chitedze. Annual milk yield per cow at Bwemba was 2580 kg for the 7/8 Friesians and 2620 kg for the Friesians and 1960 and 2070 kg, respectively, at Chitedze. Thus, the performances of the 7/8 Friesians and the pure Friesians were similar at the two units, while age at first calving was 20% lower and milk yield 30% higher at Bwemba than at Chitedze.
The most readily identifiable differences in management between the two centres which might account for the observed differences in performance are the seasonal breeding practices and the constant level of concentrate feeding at a rate of 4 kg per cow per day at Chitedze, as opposed to continuous breeding and differential concentrate feeding according to production as practiced in Bwemba.
The crossbred cattle on smallholder farms in the Southern Region of Malawi were developed from Friesian bulls and 'off-type' cows (a mixture of Sussex, Brahman-type and Africander-cross cattle), while the crossbred cattle at Bwemba, Chitedze and on smallholder farms in the Central Region were based on the Friesian and the Malawi Zebu. A comparison was made between the performance of the larger, Friesian-'off-type' crosses in the relatively feed-deficient Southern Region and the smaller Friesian-Malawi Zebu crosses in the Central Region. Because there were no data on crossbred cattle on smallholder farms in the Central Region the mean performance of Friesian-'off-type' cattle on smallholder farms and at Tuchila was compared with the performance of the Friesian-Malawi Zebu at either Chitedze or Bwemba or their mean performance at the two stations.
Ages at first calving for 3/4 and 7/8 Friesians were 35 and 36 months, respectively, in the Southern Region, and 43 and 46 months in the Central Region. The mean yields per lactation day for the 1/2, 3/4 and 7/8 Friesians in the Southern Region were 5.2, 8.2 and 8.3 kg, respectively, compared with 5.6, 7.1 and 8.1 kg in the Central Region. The mean annual milk yield per cow of the 7/8 Friesians at Tuchila in the Southern Region was 2600 kg, compared with 2580 kg at Bwemba in the Central Region. The mean annual milk yield per cow of the 15/16-Friesians was 3000 and 2650 kg at Tuchila and Bwemba, respectively.
Thus, apart from the lower age at first calving of the crosses in the Southern Region, the Friesian Malawi Zebu crossbred cattle in the Central Region performed at the same level as the Friesian-off-type' crossbred cattle in the south, in spite of the larger body size of the Friesian-'off-type' crosses. These data suggest that there is little reason why the Malawi Zebu should not be used to produce crossbred cows for smallholders in the Southern Region. The smaller body size of the Friesian-Malawi Zebu crosses is an advantage in the Southern Region where feed resources are less than in the Central Region.
Information on age at first calving was not available for Mikolongwe because birth dates of cows were not known. Pure Friesians at nearby Tuchila, under similar management, calved first at 37 months of age, which was the same as observed at Bwemba, but 8 months younger than the estimated figure for Chitedze.
Mean yields per lactation day for Friesians were 9.7, 9.5 and 7.4 kg at Mikolongwe, Bwemba and Chitedze, respectively.
Thus, the performances of Friesian cattle at Mikolongwe and Bwemba were very similar in spite of the differences between the environments. This suggests that herd management can minimise the effects of environmental factors that have short-term influences on dairy production. The difference between the figures from the research station at Chitedze and the multiplication units suggests that there is a lack of consultation between research and field activities relative to the development of a common direction in national livestock policies and goals.
