https://repository.maseno.ac.ke/handle/123456789/699 Fri, 15 May 2026 13:14:59 GMT 2026-05-15T13:14:59Z https://repository.maseno.ac.ke/handle/123456789/6399 Genetic analysis of reproductive performance of large white sows in western Kenya KADENYI, Milka Agwona Accurate estimation of genetic parameters is important in animal evaluation to effectively sustain reproductive performance, while accounting for sources of variation in animal performance. The pig improvement program is under implementation; however, accurate estimates of performance parameters are largely lacking. KALRO is at the forefront of pig genetic improvement, breeding research, and dissemination of improved pig technologies. They have implemented breed evaluation programs, particularly for the Large White and Landrace breeds. KALRO also develops feeding regimes, disease control programs, and farmer training modules. This study aimed to conduct a genetic analysis of the reproductive performance of sows in Western Kenya by: (i) evaluating the non-genetic sources of variation in sow reproductive performance, which include herd, season of birth, year of birth, season of farrowing, and year of farrowing, and (ii) estimating variance components and genetic parameters of sow reproductive performance. Data were collected on reproductive performance records of Large White sows obtained from 2010 to 2022. Data on reproductive traits, namely litter size at birth (LSB), number of piglets born alive (NPBA), litter size at weaning (LSW), and inter-farrowing interval (IFI), were obtained from pig farms in Kisumu and Trans-Nzoia counties. Non-genetic sources of variation in reproductive traits were determined by fitting reproductive data to a fixed-effect model in a generalized linear model using R software. Estimates of variance components and genetic parameters were obtained by fitting a multivariate animal model to the data in WOMBAT. The fixed part of the model comprised herd, year of birth (Yob), season of birth (Sob), year of farrowing (Yof), season of farrowing (Sof), parity, and LSB, among which Yof, Yob, herd, and LSB were found to have a significant effect on reproductive performance. There was low genetic variance compared to phenotypic variance, and high phenotypic correlation estimates were observed between LSB and LSW (0.66±0.12) and between NPBA and LSW (0.82±0.01). Heritability estimates were 0.014±0.040 for LSB, 0.011±0.039 for NPBA, 0.001±0.035 for LSW, and 0.039±0.038 for IFI. These low heritability estimates suggest that genetic improvement through selection will be slow. Analysis of non-genetic sources of variation revealed that herd management and seasonality of years in terms of rainfall were significant sources of variation in sow reproductive traits, underscoring the importance of management and environmental factors in optimizing sow productivity. Additionally, the estimated variance components and genetic parameters showed that heritability estimates for sow reproductive traits were generally low, suggesting limited genetic variability and potential for response to selection. While strong phenotypic correlations were observed among the litter traits, some genetic correlations were antagonistic, indicating that selection for one trait may negatively affect others if not carefully balanced. Therefore, there should be cautious implementation of genetic selection to avoid compromising correlated traits. Master's Thesis Tue, 11 Nov 2025 00:00:00 GMT https://repository.maseno.ac.ke/handle/123456789/6399 2025-11-11T00:00:00Z https://repository.maseno.ac.ke/handle/123456789/5229 Habitat characteristics and population structure of the fishes of the upper Victoria Nile, Uganda BASSA, Samuel Globally, riverine fishes are important in supplementing lacustrine fish production. In Uganda, Upper Victoria Nile (UVN) is considered as a critical habitat to fish species reproduction, feeding, shelter and as source of food to the community. Yet information on population dynamics of resident fish species, biological integrity of riverine ecosystem, habitat quality is not known and catch rates of fish species in UVN are scanty. Further, information of the species Mormyrus kannume on growth patterns and exploitation is unknown. The main objective of the study was to determine habitat characteristics and population structure of the fishes of UVN. Specific objectives were: i) To characterise habitat quality in relation to physico-chemical parameters and fish community structure in UVN; ii) To determine the population dynamics of fish in UVN; iii) To determine trends in fishing effort and fish catches in UVN; and iv) To determine spatial and temporal abundance of bait fishery in UVN. The study covered twelve stations distributed between station 1 (ST1) to ST12. Out of twelve sampling stations, three were for catch assessment and effort data, while nine were for collection of fisheries, limnology, and ecosystem integrity datasets. Data were collected biannually from April 2014 to September 2019. Physico-chemical variables of water were measured using HacH HQ40d multi probe. Water samples were obtained in duplicate using 500mm borosilicate bottles prewashed with distilled water and nutrient analysis in laboratory was done following standard methods. Principle Component Analysis was used in water quality analysis. Nine-habitat metrics estimated habitat quality index (HQI). Fish biodiversity indices were estimated using occurrence and fish-based index of biotic integrity (FIBI) methods. Counts of exotic/indigenous and tolerant/intolerant species were recorded to generate species richness. Generated measurements were used to develop 12 metrics FIBI by summing up scores. Duplicate samples of fish were obtained using experimental gillnets of mesh sizes ranging from 25.4-203.2 mm. Fish Stock Assessment Tool (FISAT) and IBM SPSS Statistic Version 20 were used in data analysis of population structure. The study mainly focused on population structure, sexual maturity, food and feeding habits, growth parameters, growth performance indices, mortality rates, and yield per recruit. Population dynamics characteristics of fish exhibited a lower size at sexual maturity (L50) for males and females. For example, L. niloticus, O. niloticus and M. kannume (L50) for males and females; 30.1 & 40.3 cm TL; 24.5 and 17.5 cm FL respectively. Fish community structure recorded5,202 fish specimens comprising 67 species belonging to 8 families. Species recorded, Lates niloticus13.82%, M. kannume 1.8%; Oreochromis niloticus0.54%,Bagrus docmac 0.41%and other including the haplochromines72%.Trophic guilds recorded omnivores (62.7%),carnivores (22.4%) and detrivores (14.9%). Mean HQI, (25.86-32.89), total fish catch and FIBI, (1.8-3.5) varied among stations that showed fair biodiversity that needed proper conservation measures of habitat type. The observed changes in annual changes were attributed to increased fishing effort along with gear changes from legal to illegal such as traps, nets below 5 inches based on Fishing rule (2010). The growth and morality parameters for commercial fishes such as L.niloticus,O.niloticus,M. kannume, O. variabilis recorded; length at infinity in centimetre total length and maximum age in years at 90.3, 8.1; 47.3,4.1 and 36.75;6.4 respectively. Total morality (Z) and exploitation rate (E) for same fish species were;Z=1.71 per year (yr-1), E=0.62; Z=2.80 yr-1, E=0.50; Z=1.74 yr-1, E=0.5 yr-1 respectively. That exhibited a decrease in population characteristics thus environmental stress. Annual fish production recorded> 70 percent low sized fishes that earned low market value. Estimated production showed high regeneration rates and often dynamic that needed regular monitoring to provide adequate information to inform management decisions. M. kannume recorded increase in annual catches and value of 40 tonnes (t) to 300 t in 2014 to 2019 respectively; though maturing at small sizes of male and females at 24.5 and 17.5 cm FL. That requires scientific attention on sustainability of the resources to avoid depletion and eventual collapse. Fri, 01 Jan 2021 00:00:00 GMT https://repository.maseno.ac.ke/handle/123456789/5229 2021-01-01T00:00:00Z