خيارات البحث
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Optimisation of breeding schemes for litter size, lambing interval, body weight and parasite resistance for sheep in Kenya
2011
Verbeek, E. | Kanis, E. | Bett, R.C. | Kosgey, I.S.
The current study optimised breeding schemes for litter size (LS), lambing interval (LI), body weight (BW) and gastrointestinal parasite resistance for sheep in Kenya. Selection for the breeding goal traits was performed in a conventional way using information on phenotypes only. For gastrointestinal parasite resistance, information on genetic makers was used, with faecal egg count (FEC) as an indicator trait. Selection for parasite resistance was partly based on field measurements and the possibilities for marker-assisted selection (MAS) were explored. Several selection schemes were defined based on whether a classical selection only was used (Latin number 1), a quantitative trait loci (QTL) for FEC was assumed to be available (2), that the correlation between FEC and BW was assumed to be positive (unfavourable-Roman I) or negative (favourable- II) and finally how FEC was included in the index (i.e., no inclusion (A), with FEC (B) or with FEC QTL (C-F)). The schemes with overlapping generations were evaluated using the computer program SelAction. Rams, ewes and total selection responses in US dollars ($) per animal, and rams' and ewes' accuracies for each scheme with a favourable or unfavourable correlation were estimated. The differences in total selection responses between schemes that did not include FEC in the selection index resulted in a response of $0.16 in scheme 1AI and $0.20 in scheme 1AII. In schemes 1BI and 1BII, FEC was included in the index. The responses in scheme 1BI and 1BII were $0.165 and $0.217, respectively. The increase in response in schemes II compared with schemes I was due to a favourable correlation between BW and FEC. The different FEC index traits had a different effect on economic response. It should be noted that increased emphasis on selection for FEC will reduce the relative responses to the breeding goal traits BW, LS and LI. Consequently, the goal of selection for FEC should be to maintain acceptable levels of gastro-intestinal parasite resistance as well as sufficient improvement of LS and BW.
اظهر المزيد [+] اقل [-]Role of traditional enclosures on the diversity of herbaceous vegetation in a semi-arid rangeland, southern Ethiopia
2010
Angassa, A. | Oba, G. | Treydte, A.C. | Weladji, R.B.
Grazing management and seasonality strongly influence the recovery potential of herbaceous vegetation in semi-arid rangelands of southern Ethiopia after history of heavy grazing. We investigated effects of management (enclosures versus grazed landscapes), age of enclosures and seasonality related to rainfall (i.e., independent variables) on herbaceous biomass, grass basal cover, herbaceous species abundance, species richness and diversity in a savanna rangeland of southern Ethiopia. We further assessed the relationship between the herbaceous biomass and species richness. Management significantly affected most of the herbaceous response variables (i.e., comparing enclosures and open grazed). Herbaceous biomass, grass basal cover, herbaceous species richness and diversity were greater in enclosures than in grazed areas. Rainfall was also influential on herbaceous biomass, grass basal cover, abundance of herbaceous species, herbaceous species richness and diversity. Herbaceous biomass, abundance and diversity did not however vary with the age of enclosures, while herbaceous species richness appeared to decrease as the age of enclosures advanced. Grass basal cover initially decreased and later on increased with the age of enclosures, so that the older enclosures disclosed improvement of grass basal cover.
اظهر المزيد [+] اقل [-]Rangeland dynamics in South Omo Zone of Southern Ethiopia: Assessment of rangeland condition in relation to altitude and Grazing types
2010
Terefe, A. | Ebro, A. | Tessema, Z.K.
Role of traditional enclosures on the diversity of herbaceous vegetation in a semi-arid rangeland, southern Ethiopia
2010
Angassa, A. | Oba, G. | Treydte, A.C. | Weladji, R.B.
Grazing management and seasonality strongly influence the recovery potential of herbaceous vegetation in semi-arid rangelands of southern Ethiopia after history of heavy grazing. We investigated effects of management (enclosures versus grazed landscapes), age of enclosures and seasonality related to rainfall (i.e., independent variables) on herbaceous biomass, grass basal cover, herbaceous species abundance, species richness and diversity in a savanna rangeland of southern Ethiopia. We further assessed the relationship between the herbaceous biomass and species richness. Management significantly affected most of the herbaceous response variables (i.e., comparing enclosures and open grazed). Herbaceous biomass, grass basal cover, herbaceous species richness and diversity were greater in enclosures than in grazed areas. Rainfall was also influential on herbaceous biomass, grass basal cover, abundance of herbaceous species, herbaceous species richness and diversity. Herbaceous biomass, abundance and diversity did not however vary with the age of enclosures, while herbaceous species richness appeared to decrease as the age of enclosures advanced. Grass basal cover initially decreased and later on increased with the age of enclosures, so that the older enclosures disclosed improvement of grass basal cover.
اظهر المزيد [+] اقل [-]Genetic analyses of N’Dama cattle breed selection schemes
2009
Bosso, N.A. | van der Waaij, E.H. | Kahi, A.K. | van Arendonk, J.A.M.
Data from the nucleus herd at the International Trypanotolerance Centre (ITC) in The Gambia were used to evaluate the current N'Dama cattle breeding scheme implemented in a low input production system. Opportunities were investigated to further improve the breeding scheme through a comparison of alternatives to the current selection strategy. A deterministic simulation model was used to demonstrate the genetic and economic benefits of the different schemes. The breeding goal consisted of daily weight gain (from 15 to 36 months of age under high tsetse challenge conditions, DWG, g/day) and milk yield (milk off-take in the first 100 days of lactation, MY, kg). Substantial genetic response per year of 3.40 kg in MY and 0.25 g/day in DWG could be achieved. Simulation results showed that early selection of nucleus sires resulted in relatively higher genetic and economic responses compared to all other schemes investigated. For a practical breeding scheme (low input system), the scheme based on early selection of nucleus sires should be recommended since this leads to the best improvements in the overall breeding goal
اظهر المزيد [+] اقل [-]Characteristics of feeding and breeding practices for intensification of smallholder dairy systems in the Kenya highlands
2008
Bebe, B.O. | Udo, H.M.J. | Thorpe, W.
This study aimed at better understanding of the characteristics of feeding and breeding practices smallholder farmers adopt in intensifying their dairy production. Use of hired labour for fodder gathering, growing of fodder crops and purchase of feeds increased with increasing intensification, but Bos taurus breeds did not respond to increasing feeding intensification while Bos indicus cattle responded, calving at earlier age and yielding more milk. Overall, first calving occurred at 32 months, but days open prolonged to 250 days with milk yield of 4 litres per day of calving interval. A principal component analysis extracted six feeding and breeding components, explaining 71.79% of the total variations in feeding and breeding practices for dairy intensification. The six components were labelled: non- intensified feeding and breeding; breeding decisions based-intensification; high external resource based-intensification; moderate resource based-intensification; resource poor based-intensification; and moderate external resource based-intensification. These characteristics points to some `evolutionary process¿ of intensification involving feeding and breeding decisions, depending on the risk-bearing capacity of the household. Intensification enhancing interventions for smallholders need be considered in the context of the household economy. Interventions on feeding and breeding have to be packaged together holistically if intensification is to enhance productivity. A selective intervention on only one of these is associated with low productivity levels, only contributing to sustaining family subsistence livelihoods
اظهر المزيد [+] اقل [-]Evaluation of the nutritive value of apple pulp mixed with different amounts of wheat straw
2008
Rodrigues, M.A.M. | Guedes, C.M. | Rodrigues, A. | Cone, J.W. | van Gelder, A.H. | Ferreira, L.M.M.
Given the high amounts of apple rejected for commercialization its use as alternative feed for ruminants should be considered. This study was designed to investigate the nutritive value of apple pulp-wheat straw mixtures. Chemical composition, in vitro organic matter digestibility (IVOMD) and gas production profiles of ensiled mixtures containing 85 (M85), 70 (M70), and 50% (M50) of apple pulp were studied at 0, 15, 30 and 45 days. Fermentation quality was assessed by pH, lactic acid, ethanol and acetate. The results showed that non fibre carbohydrates (NFC) decreased along the storage period while DM stabilized after 30 days. It was also shown that pH increased along the storage period and the highest values for ethanol and acetic acid concentrations were observed in the apple pulp mixtures (Apple). Within mixtures, IVOMD decreased along the storage period, being however similar across mixtures after long periods of storage. Gas production analysis indicated that easily fermentable components (VFA) and the less easily fermentable constituents (VFB) decreased along the storage period, but VFB showed no differences between mixtures for the first two storage periods. Results suggest the possibility of reducing ethanol concentration of apple pulp silages through the incorporation of fibrous components; however silage additives to limit fermentation of sugars into ethanol should be used to ensure the course of the conservation process.
اظهر المزيد [+] اقل [-]Evaluation of the nutritive value of apple pulp mixed with different amounts of wheat straw
2008
Rodrigues, M.A.M. | Guedes, C.M. | Rodrigues, A. | Cone, J.W. | Gelder, A.H. van | Ferreira, L.M.M.
Socio-economic factors influencing small ruminant breeding in Kenya
2007
Verbeek, E. | Kanis, E. | Baker, R.L. | Kosgey, I.S.
In order to design an effective small ruminant (i.e., goats and sheep) breeding program in Kenya and other areas with similar production circumstances, it is important to understand the socio-economic factors applying to the relevant production system. Information on these was obtained from a questionnaire carried out on both smallholders and pastoral/ extensive farmers in seven selected districts. From the 458 responding households, 18% kept only goats, 34% kept only sheep, and 48% kept both species. Goats were generally ranked lower in popularity. The most represented breeds in the households were the indigenous East African goat and the Red Maasai sheep, and crossbred genotypes of goats and sheep. However, according to the farmers, the pure breeds were more popular than the crossbreeds. The households owned the majority of the used land for small ruminant production. In many cases, male household members were in control of the land. Animals were in most cases owned by the household head only or by both the household head and the spouse. The most important water source for animals was the river with the frequency of watering in the dry season in some cases being as low as once a day. Both males and females made most decisions in smallholder households. Women in the pastoral/ extensive systems participated less significantly in decision making than those in smallholder households, although they were responsible to many animal production related activities.
اظهر المزيد [+] اقل [-]Estimation and comparison of benefits due to feeding hay and silage during the dry season on commercial dual-purpose cattle production systems in Honduras and Costa Rica
2006
Schoonhoven, A.D. | Holmann, F. | Argel, P. | Ordoñez, J.C. | Chaves, J.
Smallholders with dual-purpose cattle production systems in most Central America experience a shortage of forages during the dry season (4-8 month. As a result, substantially lower milk production and weight gain occurs. Dual-purpose operations seeking to maximize milk and beef production in the dry season can produce and feed hay or silage to their livestock. The increase in milk and beef production due to feeding hay or silage during the dry season on commercial dual-purpose cattle productions systems, the production costs of making silage or hay and the benefits as a result of feeding silage or hay are estimated and compared in Honduras and Costa Rica. Due to feeding silage or hay, farmers in Honduras and Costa Rica have increased milk production during the dry season. The costs of feeding hay are lower in both countries, although farmers feed a higher amount (kg DM/cow/ day) than silage. Feeding silage or hay to milking cows is profitable in both countries. The income-cost ratio and the net benefit ($/ cow/day) due to feeding these feedstuffs are positive. Farmers with milking cows in Honduras realise a higher income-cost ratio and net benefit due to feeding silage and hay than farmers in Costa Rica. Likewise, beef cows or young livestock supplemented with these feeding alternatives don't loose weight during the dry season. In Honduras as well in Costa Rica, it is profitable to feed silage or hay to beef cows or young livestock. Currently, no silage and a small hay market exist in Honduras. Possibly, these will develop due to an increasing demand for these profitable feedstuffs. In Costa Rica thanks to the efforts of agricultural organisations, a hay market of different qualities is developing.
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