By
J C M Trail and K E Gregory
PUBLISHED BY INTERNATIONAL LIVESTOCK CENTRE FOR AFRICA 1981
P. O. BOX 5689 ADDIS ABABA ETHIOPIA
ILCA PUBLICATIONS
The International Livestock Centre for Africa (ILCA) is an autonomous research and information centre, whose activities and publications are funded by the Consultative Group on International Agricultural Research (CGIAR). The CGIAR members which have funded ILCA to date are the international Development Research Centre, the United Nations Development Programme, the World Bank and the governments of Australia, Belgium, the Federal Republic of Germany France, Iran, the Netherlands, Nigeria, Norway, Saudi Arabia, Sweden Switzerland, the United Kingdom and the United States of America. Responsibility for ILCA publications, however, rests solely with the centre and such other parties as may be cited as joint authors.
ILCA Monographs and Systems Studies are currently ILCA's two series of scientific publications. Both present information concerned with livestock production systems of tropical Africa, though Systems Studies deal with systems as a whole, while Monographs deal with aspects of systems and range widely in subject matter.
ABSTRACT
Productivity data were analyzed from five cattle herds, including Sahiwals, varying percentages of Sahiwal/Ayrshire crossbreds, Small East African Zebus and Borans, across a range of production systems and management levels in Kenya. Examination of environmental and genetic parameters indicates that the formation of composite breeds is a promising approach to producing cattle adapted to the major ecological zones and production systems of Africa. Such composites would include an optimum percentage of the highest performing Bos indicus breeds, such as the Sahiwal, to achieve adaptability to the production environment, combined with Bos taurus breeds which have a high response capability for milk and beef production.
KEY WORDS
Sahiwal, Ayrshire, Africa, Kenya, environmental effects, breed effects, heterosis, composite breeds, milk, beef, productivity index.
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2.1 Background information
2.2 Results and discussion
2.2.3.1 Birth weight.
2.2.3.2 Average daily gain from birth to 50 kg.
2.2.3.3 Average daily gain from 50 to 90 kg.
2.2.3.4 Average daily gain from birth to 90 kg.
3.1 Background information
3.2 Results and discussion
3.2.2.1 Milk extracted.
3.2.2.2 Estimated milk consumed by calf.
3.2.2.3 Estimated total milk production.
3.2.2.4 Total lactation yield.
3.2.2.5 Daily milk yield.
3.2.2.6 Lactation length.
3.2.2.7 Length of dry period.
3.2.3.1 Birth weight.
3.2.3.2 Weaning weight.
3.2.3.3 Postweaning growth of heifers up to 2 years.
4.1 Background information
4.2 Results and discussion
4.2.2.1 Lactation yield.
4.2.2.2 Lactation length.
4.2.2.3 Daily milk yield.4.2.3.1 Weaning weight.
4.2.3.2 Steer weights adjusted to constant ages of 27, 30 and 36 months.4.2.5 Index of cow productivity
4.2.6 Heterosis and reciprocal effects
5.1 Background information
5.2 Results and discussion
5.2.2.1 Weaning weight.
5.2.2.2 Adjusted weight of heifers at 660 days.
5.2.2.3 Adjusted weight of hulls at 18, 24 and 30 months.
6.1 Background information
6.2 Results and discussion
6.2.2.1 Lactation yield.
6.2.2.2 Lactation length.
6.2.2.3 Daily milk yield.
7. Breed and environmental effects on productivity levels
7.1 Summary of the production potential of the five sites
7.2 Productivity of different breeds and crosses
7.3 Rainfall effects
7.4 Seasonal variation
7.5 Year effects
7.6 Parturition effects
8. The formation of composite breeds using Sahiwal cattle
8.1 The objectives of crossbreeding
8.2 The formation of composite breeds as an alternative to rotational crossbreeding systems
8.3 The use of composite breeds with a Sahiwal component in tropical Africa