22207 Records out of 22207 Records

Evaluation of functional traits in Holstein-Friesian cattle on large scale farms in Kenya

Author: Menjo, Dominic

Awarding University: Egerton University, Kenya

Level : MSc

Year: 0

Holding Libraries: Egerton University Library ; International Livestock Research Institute Library ;

Subject Terms: Cattle ; Milk ; Holstein-Friesian ; Breeding of animals ;

Abstract:

The use of imported semen within the Holstein-Friesian population in Kenya has contributed to increases in milk production per cow. However, information on how this impacts on functional traits, particularly early life survival and reproductive traits of dairy cattle, is lacking. This study evaluated age at first calving (AFC), survival to age at first calving (SAFC), and survival to four years of age (51460) in the Holstein-Friesian cattle populations of four medium to large-scale dairy farms in Nakuru district of Kenya. The records used were for the period 1990 to 2003. Environmental factors were evaluated for all the three traits, and genetic parameter estimates obtained for AFC. The average AFC was 1058 + 159 days with a heritabi I ity estimate of 0.15 ?-0.06. On average, daughters of dams with sires originating from New Zealand and Australia had an earlier AFC (907 days) relative to those with sires from Europe (1031 days). To evaluate SAFC and 51460, a survival analysis was carried out using the survival kit. On average, 25% of all the animals born on the four farms were culled prior to attaining a first calving. While the highest proportion of losses was due to unspecifiedreasons, the relative risk of being culled was highest when an animal had a specific disease. The first 60 days of life were the most critical for early survival. The herd, year-season of birth and sire region of origin significantly (p<O.OO1) affected mortality and culling rates. Daughters of sires from South Africa and Israel tended to have better survival rates than those with sires originating in other regions. From the analyses, it was evident that some unfavourable selection was practiced towards animals sired by Kenyanborn bulls. To facilitate accurate assessment of causes of mortality and culling, record keeping on health management is important. The use of sires from heterogeneous sources without a clearly defined breeding objective other than increased milk production potential is negatively impacting on early survival of Holsteins on large-scale dairy farms in Kenya. Economic implications of losses before attaining a productive age need to be evaluated in order to formulate intervention strategies for livestock producers to make informed decisions on choice of sires for breeding.

Review methods of estimating parameters in known linear mixed-effective (nlme) models

Author: Mbunzi, Stephen

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 0

Holding Libraries: International Livestock Research Institute Library ;

Subject Terms: Sheep ; Statistics ; Genetics ; Linear mixed effects ; Computer based modeling ; Nonlinear programming ;

Abstract:

This study is a critical review of theoretical issues that underline the linear mixed effects (LME) and nonlinear mixed effects (NLME) models. These two areas revisited under maximum likelihood and restricted maximum likelihood estimation frameworks. We also review methods of estimating parameters in both linear and nonlinear mixed effects models. In the case of LME, we consider different ways of developing the likelihood estimators, key among these methods are the 'pseudo-data' approach, orthogonal triangular decomposition method and use of penalized least squares problem. For NLME, we intended to investigate the computational efficiency and accuracy of computational methods, like the b-splines, that could be used to approximate the log-likehood function in non-linear mixed effects models. This was not achieved in this study but can be an interesting area for further research work. We critically review the four methods of estimating parameters by Pinheiro and Bates (1995) through proving a number of lemmas. Our proofs led us to same stated results by different researchers in different papers. This is a key issue in the investigation of other expansion methods and comparing their computational efficiency and accuracy with these existing ones. We conclude by giving an insight into linear mixed effects models by analyzing a data set from livestock where we examine incorporation of random effects to study variations among rams (sires) and ewes (dams) and their influences on lamb weaning weight. Factors like year of birth of the lamb, sex of lamb, age at weaning, age of dam, ewe breed and ram breeds. It was our intention to obtain heritability estimates which determine the proportion of the variation among offspring that have been handed down from parents out of these random estimates. Keywords: repeated-measures data, multilevel data, longitudinal data, LIME, NLME, 'pseudo-data and b-splines.

Adult literacy in Dagoretti Division : the problems encountered and some possible solutions.

Author: Lung'aho, S

Awarding University: Kenyatta University, Kenya

Level :

Year: 0

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Adult education ; Dagoretti Division, Nairobi, Kenya ; Literacy ;

Abstract:

ABSTRACT NOT AVAILABLE

China and East Africa, 1960-1974

Author: Lin, B

Awarding University: University of Wales, Aberystwyth

Level : PhD

Year: 0

Holding Libraries: Institute of Commonwealth Studies Library ;

Subject Terms: International relations ; East Africa ; China ;

Abstract:

ABSTRACT NOT AVAILABLE

A case study analysis of the benefits and shortcomings of biennial budgeting : the experience of United Nations Office, Nairobi.

Author: Mugambi, Raymond K

Awarding University: United States International University-Africa, Kenya

Level : MBA

Year: 0

Holding Libraries: United States International University-Africa Library ;

Subject Terms: United Nations ; Budgeting ;

Abstract:

ABSTRACT NOT AVAILABLE

Genetic incompatibilities among populations of cassava green mite complex Mononychellus SPP. (Acari : Tetranychidae) and their implication in the taxonomy of the mite.

Author: Murega, Thomas Ngigi

Awarding University: Rivers State University of Science and Technology, Nigeria

Level : PhD

Year: 0

Holding Libraries: International Centre of Insect Physiology and Ecology Library ; Kenya Agricultural Research Institute Headquarters Library ; University of Nairobi Chiromo Library ;

Subject Terms: Mononychellus tanajoa ; Aculops lycopersica ; Classification ;

Abstract:

ABSTRACT NOT AVAILABLE

Mechanisms of sorghum resistance to the spotted stalkborer, Chilo partellus (Swinhoe) Lepidoptera Pyralidae.

Author: Masina, Greenman Themba

Awarding University: University of Nairobi, Kenya

Level : PhD

Year: 0

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ; International Centre of Insect Physiology and Ecology Library ;

Subject Terms: Sorghum ; Spotted stalk borer USE Chilo partellus ; Butterflies and moths ;

Abstract:

Stalkborers are some of the most important pests of cereal crops in the tropics and in particular the semi-arid areas. Chilo partellus, the spotted stalkborer, is one of the most notorious pests of sorghum in that it occurs in almost all the areas where sorghum is grown in the semi-arid regions of Asia and Africa. Lately it has been found that this pest is gradually increasing its range and importance. Of the various sorghum pest control methods available in the semi-arid regions none holds better 'prospects than the use of resistant varieties. In this study several experiments were conducted to elucidate the mechanisms of resistance of different sorghum cultivars and also to propose the methodology for mechanisms of resistance studies. Accordingly five criteria were used - for explaining these mechanisms. These criteria were : (a) Preference or Non-preference for oviposition of the moth on different sorghum cultivars, (b) Larval establishment of Chilo partellus larvae first instarL on different sorghum cultivars, (c) Relative leaf damage and stem tunnelling in different sorghum cultivars by C. partellus larvae, (d) Biophysical and prelimary biochemical studies that elucidate the differences in cultivar susceptibility to C. partellus, and (e) studies on different cultivar tolerances to C. partellus damage. The oviposition preference studies revealed that sorghum cultivars differed in their suitability as a C. partellus oviposition substrate. Cultivar IS 2205 was the least preferred while IS 18363 was the most preferred. Experiments to identify the factors responsible were inconclusive. Evidence pointed to both biochemical and biophysical factors. First instar larval establishment studies were also inconclusive even though it was demonstrated that larval establishment was different among the cultivars used. The only definite evidence for poor establishment in some cultivars was biophysical.Different cultivars were significantly different in their susceptibility to leaf damage. The tendency to form deadhearts was also significantly different . But reasons for these differences were not apparent. Cultivars were not significantly different in their susceptibility to tunnelling even though they had different amounts of fibre, lignin and sucrose. The single most important factor for the different cultivar susceptibilities was in their different tolerances to C. partellus attack. Tillering, in particular, was demonstrated to play an important role in compensation for damage. The ability to flower and to produce seed inspite of having a high infestation were also very significant. Susceptible cultivars dried up before they had flowered. Others still, flowered but could not form seed. Using tolerance as a criterion for resistance showed IS 18520 to be the most resistant. Formation of multiple heads was also shown to be an important factor. Different cultivars had varying effects on the development of C. partellus (antibiosis). However , the antibiotic effect was either insignificant or only just significant statistically.

Reproductive health policy in Kenya since c 1950

Author: Majisu, Amanda M

Awarding University: University of Durham, England

Level : PhD

Year: 0

Holding Libraries: Institute of Commonwealth Studies Library ;

Subject Terms: Reproductive health ; Health care ;

Abstract:

ABSTRACT NOT AVAILABLE

The role of sex education knowledge in shaping the sexual behaviour of adolescents in primary school in Thika District, Kenya

Author: Muruiri, Joyce

Awarding University: University of Reading, England

Level : MPhil/PhD

Year: 0

Holding Libraries: Institute of Commonwealth Studies Library ;

Subject Terms: Sex education ; Sexual behavior ; Teenagers ; Primary school students ; Thika District ;

Abstract:

ABSTRACT NOT AVAILABLE

Interest of the state : an inquiry into the impact of patterns of state-society incorporation and disengagement on the protection of refugees in Kenya

Author: Mwangi, Annabel N

Awarding University: University of Oxford, England

Level :

Year: 0

Holding Libraries: Institute of Commonwealth Studies Library ;

Subject Terms: Refugees ; International relations ;

Abstract:

ABSTRACT NOT AVAILABLE