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1.
S. Gizaw J.A.M. van Arendonk A. Valle‐Zárate A. Haile B. Rischkowsky T. Dessie A.O. Mwai 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2014,131(5):350-357
A simulation study was conducted to optimize a cooperative village‐based sheep breeding scheme for Menz sheep of Ethiopia. Genetic gains and profits were estimated under nine levels of farmers' participation and three scenarios of controlled breeding achieved in the breeding programme, as well as under three cooperative flock sizes, ewe to ram mating ratios and durations of ram use for breeding. Under fully controlled breeding, that is, when there is no gene flow between participating (P) and non‐participating (NP) flocks, profits ranged from Birr 36.9 at 90% of participation to Birr 21.3 at 10% of participation. However, genetic progress was not affected adversely. When there was gene flow from the NP to P flocks, profits declined from Birr 28.6 to Birr ?3.7 as participation declined from 90 to 10%. Under the two‐way gene flow model (i.e. when P and NP flocks are herded mixed in communal grazing areas), NP flocks benefited from the genetic gain achieved in the P flocks, but the benefits declined sharply when participation declined beyond 60%. Our results indicate that a cooperative breeding group can be established with as low as 600 breeding ewes mated at a ratio of 45 ewes to one ram, and the rams being used for breeding for a period of two years. This study showed that farmer cooperation is crucial to effect genetic improvement under smallholder low‐input sheep farming systems. 相似文献
2.
Wurzinger M Ndumu D Baumung R Drucker A Okeyo AM Semambo DK Byamungu N Sölkner J 《Tropical animal health and production》2006,38(7-8):571-581
A survey in Burundi, Rwanda, Tanzania and Uganda was conducted in order to determine the different production systems under
which Ankole cattle are currently kept. Additionally, selection criteria of livestock keepers were documented. In Burundi,
Rwanda and parts of Uganda, livestock keepers are sedentary and herds are small, whereas in the other areas Ankole cattle
are kept in large herds, some of them still under a (semi-)nomadic system. Milk is the main product in all areas, and is partly
for home consumption and partly for sale. Although the production systems vary in many aspects, the selection criteria for
cows are similar. Productive traits such as milk yield, fertility and body size were ranked highly. For bulls, the trait ‘growth’
was ranked highly in all study areas. Phenotypic features (coat colour, horn shape and size) and ancestral information are
more important in bulls than in cows. The only adaptive trait mentioned by livestock keepers was disease resistance. In areas
of land scarcity (Burundi, Rwanda, western Uganda), a clear trend from pure Ankole cattle towards cross-bred animals can be
observed. 相似文献
3.
Mirkena T Duguma G Willam A Wurzinger M Haile A Rischkowsky B Okeyo AM Tibbo M Solkner J 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2012,129(3):244-253
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. 相似文献
4.
Johann Sölkner Heinrich Grausgruber Ally Mwai Okeyo Peter Ruckenbauer Maria Wurzinger 《Euphytica》2008,161(1-2):273-282
Breeding objectives always involve consideration of multiple traits, even in situations where output of a single trait is
dominant. We review literature dealing with formal definition of breeding objectives. Involvement of farmers in the process
of setting up breeding objectives is also considered. In the optimal selection index, the relative importance of a trait is
scaled by its economic value, derived as marginal profit related to a change in expression of defined size. Normative approaches
to derive economic values use partial derivatives of a profit equation with respect to the traits involved or model the bio-economic
system with various techniques. The theory is well developed and includes consideration of non-linear profit functions and
traits with an intermediate optimum. It is frequently applied in animal breeding. In dairy cattle breeding, a major change
of focus from traits related to output (i.e., milk yield) to traits related to cost of input (health, fertility, feed efficiency)
has taken place recently. Plant breeders find the concept of deriving relative economic weights of traits difficult to apply
and often replace the optimal index by restricted or desired gains indices. A change of paradigms similar to that in cattle
breeding seems advisable. Participatory approaches to evaluate the relative importance of traits are more frequently applied
in plant breeding than in animal breeding. We review two studies, dealing with methods of acquiring information about selection
criteria of farmers planting maize in the Ethiopian highlands and of pastoralists keeping cattle in Uganda, in detail. 相似文献
5.
6.
D.B. Ndumu R. Baumung M. Wurzinger A.G. Drucker A.M. Okeyo D. Semambo J. Slkner 《Livestock Science》2008,113(2-3):234-242
Ankole cattle are well known for their massive white horns and red coat colour. These characteristics are attributed to centuries of cultural breeding practices. Two experiments with traditional cattle keepers were carried out at a governmental Ankole nucleus farm in south-western Uganda to identify phenotypic characteristics as well as production and fitness traits which are important indigenous selection criteria. Forty one body measurements each were taken from 15 bulls and 35 cows and phenotypic characteristics were described in detail. In the first experiment 12 groups of 6 to 8 cattle keepers were invited to rank several groups of 4–5 animals according to their preference for a breeding bull or cow based on phenotype alone. In the second experiment the ranking was based on phenotype and a hypothetical life history that was randomly assigned to each animal on each day of experiment. The history included milk yield (on own performance for cows and that of the dam for bulls), fertility of the animal and its sire as well as events of East Coast Fever. For analysis, Generalized Multinomial Logit Models were fitted. To compare different models the likelihood-based pseudo R square measure was used. The results indicate that, in the selection of cows, performance and fitness traits are emphasized by the cattle keepers while in the selection of bulls, the phenotypic appearance of the animal plays an important role. Individual fertility followed by milk performance are the main criteria for selecting cows, resistance to East Coast Fever was of highest importance in bulls. In both sexes a dark red coat colour was highly rated. The study indicates that the methodology of preference ranking combining phenotype and a hypothetical life history may provide insight into indigenous selection criteria of stock owners elsewhere. 相似文献
7.
Assessment of genetic diversity is a prerequisite for the management and conservation of animal genetic resources. Appropriate
design of breeding programmes is therefore impossible for breeds that have not been adequately characterized either phenotypically
and/or genetically. Phenotypic characteristics are important in breed identification and classification in ways that farming
communities can relate with. This study phenotypically characterized two breeds of zebu cattle in Kenya. A total of 12 measurements
(face length, ear length, horn length, heart girth, height at withers, chest depth, body length, height at rump, pelvis width,
corpus length, pin bone width and tail length) were collected on 373 Maasai and 277 Kamba zebu kept by traditional farmers
in south-east Kenya. The data were classified on the basis of breed group, age group, sex and coat colour pattern. Breed group,
age group and sex significantly influenced all measurements. Coat colour pattern significantly influenced only height at withers,
corpus length, ear length and tail length. Except for horn and ear length, all the other measurements were significantly higher
for the Maasai zebu. Additionally, the Maasai zebu was taller than it was long. The opposite was true for the Kamba zebu.
The Maasai and Kamba zebus can be classified as medium-sized breeds; however, great variations exist in their body sizes within
and between the breeds. 相似文献
8.
Kugonza DR Kiwuwa GH Mpairwe D Jianlin H Nabasirye M Okeyo AM Hanotte O 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2012,129(1):30-40
This study aimed to estimate the level of relatedness within Ankole cattle herds using autosomal microsatellite markers and to assess the accuracy of relationship assignment based on farmers' memory. Eight cattle populations (four from each of two counties in Mbarara district in Uganda) were studied. Cattle in each population shared varying degrees of relatedness (first-, second- and third-degree relatives and unrelated individuals). Only memory-based kinship assignments which farmers knew with some confidence were tested in this experiment. DNA isolated from the blood of a subsample of 304 animals was analysed using 19 microsatellite markers. Average within population relatedness coefficients ranged from 0.010 ± 0.005 (Nshaara) to 0.067 ± 0.004 (Tayebwa). An exclusion probability of 99.9% was observed for both sire-offspring and dam-offspring relationships using the entire panel of 19 markers. Confidence from likelihood tests performed on 292 dyads showed that first-degree relatives were more easily correctly assigned by farmers than second-degree ones (p < 0.01), which were also easier to assign than third-degree relatives (p < 0.01). Accuracy of kinship assignment by the farmers was 91.9% ± 5.0 for dam-offspring dyads, 85.5% ± 3.4 for sire-offspring dyads, 75.6% ± 12.3 for half-sib and 60.0% ± 5.0 for grand dam-grand offspring dyads. Herd size, number of dyads assigned and length of time spent by the herder with their cattle population did not correlate with error in memorizing relationships. However, herd size strongly correlated with number of dyads assigned by the herder (r = 0.967, p < 0.001). Overall, we conclude that memorized records of pastoralists can be used to trace relationships and for pedigree reconstruction within Ankole cattle populations, but with the awareness that herd size constrains the number of kinship assignments remembered by the farmer. 相似文献
9.
This paper reports the variation in five blood proteins from five populations of sheep found in Kenya. Blood samples were collected from a total of 309 adult sheep of both sexes in Kwale, Makueni and Kakamega districts for the fat-tailed sheep and in Isiolo district for the fat-rumped hair sheep. Fine-wooled Merino sheep were used in this study as the reference population. Transferrin, esterase-A and esterase-C were polymorphic in all the populations investigated, while albumin was monomorphic for the S allele in the fat-tailed sheep and haemoglobin was fixed for the B allele in the Kwale, Makueni and Isiolo populations. Phylogenies derived from the pairwise genetic distance estimates showed a clear separation between the indigenous sheep populations and the exotic Merino. However, the topology of the former showed rather poor consistency with their morphological classification based on the localization of their fat deposits, namely fat-tailed or fat-rumped hair sheep. 相似文献
10.
R. Roschinsky H. Mulindwa E. Galukande M. Wurzinger D. Mpairwe A. M. Okeyo J. Sölkner 《Grass and Forage Science》2012,67(2):199-209
The Bahima ethnic group have been crossbreeding autochthonous Ankole with Holstein‐Friesian cattle. Separate herds (pure Ankole and crossbreds) are common. A survey was conducted to characterize pasture utilization and management in the Ankole region to gain a better understanding of current and emerging practices. Herds are largely grazed by continuous stocking although there are efforts to establish paddocks. Factors considered for pasture allocation to cattle genotypes were high‐quality feed, limited shrubs/weeds and close proximity to homestead for 80, 80 and 30% of farmers, respectively. Cross‐bred cattle were kept on medium/high‐quality, and Ankole cattle on medium/low‐quality pastures. Pastures for cross‐bred cattle yielded 0·17 t ha?1 more dry matter than pastures allocated to Ankole cattle. Crude protein (CP) content of Ankole pasture was significantly (P < 0·05) lower than CP of cross‐bred pasture (6·3% compared with 7·3%). Neutral detergent fibre content was similar (72·8% vs. 69·8%) for both pasture types. Farmers’ perceptions of indicator plant species were important for allocation of pasture. Hyparrhenia rufa, Brachiaria spp., Themeda triandra and Chloris gayana were identified as the preferred pasture species. Sporobolus pyramidalis and Cymbopogon afronardus were the most undesirable pasture species. Brachiaria spp. offers an opportunity for utilization as hay for dry season supplementation. 相似文献