Breeding programmes described as community-based (CBBP) typically relate to low-input systems with farmers having a common interest to improve and share their genetic resources. CBBPs are more frequent with keepers of small ruminants, in particular smallholders of local breeds, than with cattle, pigs or chickens with which farmers may have easier access to alternative programmes. Constraints that limit the adoption of conventional breeding technologies in low-input systems cover a range of organizational and technical aspects. The analysis of 8 CBBPs located in countries of Latin-America, Africa and Asia highlights the importance of bottom-up approaches and involvement of local institutions in the planning and implementation stages. The analysis also reveals a high dependence of these programmes on organizational, technical and financial support. Completely self-sustained CBBPs seem to be difficult to realize. There is a need to implement and document formal socio-economic evaluations of CBBPs to provide governments and other development agencies with the information necessary for creating sustainable CBBPs at larger scales.
Based on the results of participatory approaches to define traits in the breeding objectives, four scenarios of ram selection and ram use were compared via deterministic modelling of breeding plans for community-based sheep breeding programmes in four diverse agro-ecological regions of Ethiopia. The regions (and production systems) were Afar (pastoral/agro-pastoral), Bonga and Horro (both mixed crop-livestock) and Menz (sheep-barley). The schemes or scenarios differed in terms of selection intensity and duration of ram use. The predicted genetic gains per year in yearling weight (kilograms) were comparable across the schemes but differed among the breeds and ranged from 0.399 to 0.440 in Afar, 0.813 to 0.894 in Bonga, 0.850 to 0.940 in Horro, and 0.616 to 0.699 in Menz. The genetic gains per year in number of lambs born per ewe bred ranged from 0.009 to 0.010 in both Bonga and Horro. The predicted genetic gain in the proportion of lambs weaned per ewe joined was nearly comparable in all breeds ranging from 0.008 to 0.011. The genetic gain per year in milk yield of Afar breed was in the order of 0.018 to 0.020 kg, while the genetic gain per generation for greasy fleece weight (kg) ranged from 0.016 to 0.024 in Menz. Generally, strong selection and shorter duration of ram use for breeding were the preferred options. The expected genetic gains are satisfactory but largely rely on accurate and continuous pedigree and performance recording.
SummaryThis paper reviews experiences with cross-breeding for milk production in the tropics. Data were compiled from 23 different studies evaluating the performance of different grades of cross-bred animals as well as local breeds. Relative performance of indigenous breeds compared with different grades of cross-breeds was calculated for three climatic zones. Traits considered were milk yield per lactation, age at first calving, services per conception, lifetime milk yield and total number of lactations completed. At 50 percent Bos taurus blood, lactation milk yields were 2.6, 2.4 and 2.2 times higher than those of local cattle in the highland, tropical wet and dry, and semi-arid climatic zones, respectively; lactation lengths increased by 1.2, 1.2 and 1.9 months in the above-mentioned climatic zones, respectively; there was a reduction in calving interval by 0.8 times and in age at first calving by 0.9 times. Similarly, cross-breds with 50 percent B. taurus genes had 1.8 times higher lifetime milk yields and a 1.2 times higher number of total lactations. Although cross-breeding faces a number of challenges such as better infrastructure, higher demand for health care, there are many advantages of using it. These are higher production per animal, higher income for the families and provision of high-value food. It is therefore likely to continue to be an important livestock improvement tool in the tropics in the future, where farmers can provide sufficient management for maintaining animals with higher input requirements and access to the milk market can be secured.Keywords: Cattle, cross-breeding, milk production, tropics ResumenEste artículo hace un repaso por las experiencias obtenidas con el cruzamiento de razas para la producción de leche en los trópicos. Se recopilaron datos de 23 estudios diferentes que evaluaron los rendimientos de animales con distinto grado de cruce así como de animales de razas autóctonas. Se compararon los rendimientos de las razas autóctonas con los de animales con distinto grado de cruce para tres zonas climáticas. Las características consideradas fueron el rendimiento lechero por lactación, la edad al primer parto, el número de servicios por concepción, la producción lechera total a lo largo de la vida del animal y el número total de lactaciones completadas. Con un 50 por ciento de sangre Bos taurus, los rendimientos lecheros por lactación fueron 2,6, 2,4 y 2,2 veces mayores que los del ganado bovino autóctono en las zonas climáticas de las Tierras Altas, Tropical Húmeda y Seca y Semiárida, respectivamente; la duración de la lactación se incrementó en 1,2, 1,2 y 1,9 meses en las zonas climáticas anteriormente mencionadas, respectivamente; el intervalo entre partos y la edad al primer parto se redujeron, respectivamente, 0,8 y 0,9 veces. Asimismo, los animales cruzados con una genética 50 por ciento Bos taurus tuvieron rendimientos lecheros, para la totalidad de su vida productiva, 1,8 veces mayores y un número total de lactaciones 1,2 veces mayor. Si bien el cruzamiento implica afr...
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