Browsing by Person "Ilatsia, Evans D."

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    Breeding strategies for Sahiwal cattle genetic resources in Kenya
    (2011) Ilatsia, Evans D.; Valle Zárate, Anne
    The Sahiwal breed is an important cattle genetic resource in the tropics where it is vital for subsistence and economic development among various communities. In Kenya a breeding and conservation programme has been in existence for over 45 years with the ascertains of its relevance in light of the producers? production aims and breeding goals still left pending. Moreover, there have been no systematic efforts undertaken to evaluate the suitability of the existing breeding programme or to examine how competitive it is compared to other alternative programmes in terms of genetic and economic merit. This thesis focused on understanding the breeding strategies for improvement of Sahiwal cattle genetic resources in Kenya. Specific objectives were; 1) to critically examine the existing breeding and conservation programmes for Sahiwal cattle genetic resources in the tropics focussing mainly on the strengths and weaknesses in Pakistan, India and Kenya as the core regions of development, 2) to understand the production conditions under which Sahiwal cattle genetic resources are raised, determine producers production aims and assess the relative importance of breeding goals and production challenges, 3) to identify and define the roles of various stakeholder institutions that are crucial in the realisation of a promising and sustainable Sahiwal cattle breeding programme, 4) to identify based on genetic and economic merits the optimal breeding programme for Sahiwal cattle genetic resources by evaluating the current and alternative breeding programmes, and 5) to analyse and discuss organisational options for implementation of promising breeding and conversion programmes. The results from the literature review study show that most studies on Sahiwal cattle genetic resources in the tropics have mainly concentrated on evaluating their performance levels with only a few published reports describing other breed characteristics. The Sahiwal breed is utilised for dairy and beef production under smallholder dairy pastoral extensive and ranching production systems both as purebreds or crossbreds. The necessary components to strengthen the breeding programme such as performance recording genetic evaluation and AI facilities exist albeit at different degree. Breeding and conservation efforts benefit from the technical and financial support from government research institutions, which also provide incentives to enhance participation in the programmes. However, breeding goals are rather informal and only defined in terms of high production levels with functional traits largely ignored. Field data analysis revealed that Sahiwal genetic resources were mainly kept for domestic milk production and for revenue generation through sales of milk and live animals. To a limited extent they were kept for breeding and also for multiple objectives that included insurance against risks and social functions. Production aims were influenced to varying extents by various household and farmer characteristics. Sahiwal cattle and their crosses were generally perceived to be better with respect to productive traits and fertility traits when compared to the EAZ. However, the EAZ was rated higher with respect to adaptation traits. The breeding objective traits of primary importance were high milk yield and big body size, good reproductive efficiency and relatively good adaptation to local production conditions. Performance and functional traits are important breeding goals that play a major role in fulfilling the multiple production objectives. This forms the basis for the optimisation of a breeding programme for sustainable utilisation to meet the needs of Sahiwal cattle producers. All the breeding programmes evaluated in this study showed positive genetic and economic gains, however, the difference was only in the margins of these benefits. Given the small population of the Sahiwal breed, an open-nucleus breeding programme is economically and genetically optimal because it will allow for efficient utilisation of the existing genetic base by allowing participation of more diverse pastoral born sires in the nucleus. The CNCROSS will continue to play an important role of facilitating the exploitation of trade-offs that exist between the Sahiwal and the EAZ with regard to production and adaption, as well as an intermediate phase in the up-grading programme. However, the full benefits of the open-nucleus breeding programme can only be realised in the presence of proper logistical organisation to facilitate exchange of breeding bulls between the pastoral herds and the nucleus farms and ensure equitable distribution. Co-operation between producers and relevant stakeholder institutions is necessary to ensure the requisite structures for implementation and sustainable execution of the breeding programme.
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    Genetic and phenotypic correlations among feed efficiency, immune and production traits in indigenous chicken of Kenya
    (2023) Miyumo, Sophie A.; Wasike, Chrilukovian B.; Ilatsia, Evans D.; Bennewitz, Jorn; Chagunda, Mizeck G. G.
    This study aimed at estimating genetic and phenotypic relationships among feed efficiency, immune and production traits measured pre- (9–20 weeks of age) and post- (12 weeks from on-set of lay) maturity. Production traits were average daily gain (ADG) and average daily feed-intake (ADFI1) in the pre-maturity period and age at first egg (AFE), average daily feed-intake (ADFI2) and average daily egg mass (EM) in the post-maturity period. Feed efficiency comprised of residual feed intake (RFI) estimated in both periods. Natural antibodies binding to keyhole limpet hemocyanin (KLH-IgM) and specific antibodies binding to Newcastle disease virus (NDV-IgG) measured at 16 and 28 weeks of age represented immune traits pre- and post-maturity, respectively. In the growing period, 1,820 records on ADG, KLH-IgM and NDV-IgG, and 1,559 records on ADFI1 and RFI were available for analyses. In the laying period, 1,340 records on AFE, EM, KLH-IgM and NDV-IgG, and 1,288 records on ADFI2 and RFI were used in the analyses. Bi-variate animal mixed model was fitted to estimate (co)variance components, heritability and correlations among the traits. The model constituted sex, population, generation, line and genotype as fixed effects, and animal and residual effects as random variables. During the growing period, moderate to high heritability (0.36–0.68) was estimated for the production traits and RFI while the antibody traits had low (0.10–0.22) heritability estimates. Post-maturity, the production traits and RFI were moderately (0.30–0.37) heritable while moderate to high (0.25–0.41) heritability was estimated for the antibody traits. Genetic correlations between feed efficiency and production traits in both periods showed that RFI had negative genetic correlations with ADG (−0.47) and EM (−0.56) but was positively correlated with ADFI1 (0.60), ADFI2 (0.74) and AFE (0.35). Among immune and production traits, KLH-IgM and NDV-IgG had negative genetic correlations with ADG (−0.22; −0.56), AFE (−0.39; −0.42) and EM (−0.35; −0.16) but were positively correlated with ADFI1 (0.41; 0.34) and ADFI2 (0.47; 0.52). Genetic correlations between RFI with KLH-IgM (0.62; 0.33) and NDV-IgG (0.58; 0.50) were positive in both production periods. Feed intake, RFI and antibody traits measured in both production periods were positively correlated with estimates ranging from 0.48 to 0.82. Results from this study indicate selection possibilities to improve production, feed efficiency and immune-competence in indigenous chicken. The genetic correlations suggest that improved feed efficiency would be associated with high growth rates, early maturing chicken, high egg mass and reduced feed intake. In contrast, improved general (KLH-IgM) and specific (NDV-IgG) immunity would result in lower growth rates and egg mass but associated with early sexual maturation and high feed intake. Unfavorable genetic correlations between feed efficiency and immune traits imply that chicken of higher productivity and antibody levels will consume more feed to support both functions. These associations indicate that selective breeding for feed efficiency and immune-competence may have genetic consequences on production traits and should therefore be accounted for in indigenous chicken improvement programs