Water Quality and Growth Performance of Nile Tilapia Fries Fed on Insect-Based Feeds

Fish feed is one of the main constraints on the growth of aquaculture in Kenya. The lack of high-quality and competitively priced feeds means that the fish farmers are unable to expand their production. To ensure that aquaculture remains viable and sustainable, it is necessary to optimize production through the utilization of locally available feeding materials. Insect-based feeds are alternative least-cost feeding resource in fish production. Using alternative protein sources such as black soldier fly larvae (BSF) and daphnia meal in place of fishmeal (Omena and Dagaa) is an ingenious strategy for sustainable fish aquaculture. This study evaluated the effect of four treatments: BSF, daphnia, Omena from Lake Victoria and Dagaa from Lake Tanganyika on the fish pond environmental parameters and fish fries’ performance (body weight and length). The experiment was carried out in a greenhouse with 30 fingerlings in each experimental unit. The feeding trials took 23 days. Results indicated that the four treatments have a varied effect on the BW and L of fish fries. A high growth rate was observed in Daphia, followed by BSF, Omena and Dagaa in that order. On the other hand, the treatments have varied effects on pond parameters with BSF promoting too much growth of algae. BSF have higher amounts of ammonia, nitrates and phosphorus, which stimulate the high growth of algae.

Evaluation of Sea-Water Intrusion in Coastal Aquifers Using both Numerical Methods and Causal Research: A Case Study of Mombasa, Kenya

This research carried out in Mombasa Island links research done in 2020 on the effects of sea-water intrusion and the current state. The aquifer in Mombasa Island is semi-confined and consists of limestone and coral rock. Water samples were collected and tested from 32 boreholes to determine chemical qualities. Results showed that chloride levels ranged from 74 mg/l to 412 mg/l, with 34% of boreholes having high chloride concentration. After modelling using MT3D program results indicated that the boreholes near the ocean were interfered by sea-water intrusion because chloride concentration was high. Control measures to prevent further sea-water intrusion should be put in place. Therefore, from a practical point of view, individuals who have sunk boreholes since 2020 try to mitigate the problem by installing Reverse Osmosis systems within their facilities, to reduce chloride levels from borehole water. The current research analyses the impact of intrusion on the installed RO systems on Mombasa Island, including cost implications, with the view of proposing viable mitigation measures. The reverse osmosis system though expensive would save a lot of chloride entering the bore holes. It is a little bit expensive though but the end results are positive and the chloride levels will reduce the cost of using too much soap.

Evaluation of Models for Longevity in a Closed Nucleus Breeding Programme: A Case Study Kenyan Sahiwal

Longevity and stay ability are parameters in any breeding programme. The Overstaying of any animal on a farm has got negative effects on the farmer. Short stay also means early exit of good animals that could have been used for a longer time and more productive. The intention of this review paper is to emphasize the importance of models that an upcoming breeding program can use without affecting the quality of the herd. In this paper, longevity is taken purely on the performance measure. The functional and type traits of longevity should be studied further before all models are put into play. But the case of closed breeding programmes, performance traits are easily measurable because many animals will exit the herd as they have been sold to farmers hence many functional straits will be expressed outside the herd. Genetic evaluation of the Kenyan Sahiwal should account for inbreeding. This study has also provided genetic and phenotypic parameters to enable the inclusion of longevity in the breeding objective for the Sahiwal cattle improvement programme.

Evaluation of the Genetic Relationship between Longevity and Growth, Milk Yield and Fertility Traits in the Sahiwal Breed in Kenya

Direct selection for longevity results in improved health and fitness and even milk production of cows. However, longevity is lowly heritable and phenotypic information is obtained at the end of an animal’s life. Traits expressed early in life and which are favorably correlated to longevity can be useful in selecting for this trait. The aim of this study was to estimate genetic correlations between longevity and age at first calving, first lactation calving interval, number of services per conception, first lactation milk yield, and first parity lactation length. Heritability estimates for measures of longevity were also calculated. The measures of longevity were time between birth and last milking in days (Long1), time between first calving and last milking record in months (Long2), number of lactations initiated (Long3), and total number of days in lactation over all lactations (Long4), total milk yield over all lactations (kg) (Long5). A series of five-variate animal models were fitted to estimate the nature and magnitude of genetic and phenotypic correlations between each measure of longevity and the fertility and production traits. Genetic correlations between measures of longevity and age at first calving, calving interval and number of services per conception were negative ranging from -0.14 ± 0.05 to -0.96 ± 0.06, -0.06 ± 0.03 to -0.67 ± 0.08 and -0.02 ± 0.02 to -0.73 ± 0.34, respectively. Correlations between measures of longevity and first lactation milk yield ranged from 0.88 ± 0.01 to 0.97 ± 0.03. Those with first parity lactation length ranged from -0.10 to 0.72. Long1, Long4 and Long5, which measure time between birth and last milking day, total number of days in lactation over all lactations and total milk yield over all lactations (kg), respectively, had the highest heritability estimates. These three could therefore be used to directly select for longevity. Among the traits studied, first lactation milk yield and age at first calving had the highest genetic correlation with measures of longevity. Therefore, first lactation milk yield and age at first calving could, therefore, be used to indirectly select for longevity.

Physical, Total Phenolic and Total Flavonoid Properties of Chia (Salvia hispanica L.) Seeds Grown in Kenya

In the recent past, there has been an increased uptake of chia seeds (Salvia hispanica L.) by consumers resulting in the increased adoption of chia farming, particularly in Kenya whereby most farmers are practising subsistence farming and a few farming it commercially. The widespread farming of chia seeds in Kenya translates to increased uptake at household level while offering a niche for industrial processing of chia seeds necessitating the need for studies on physical, total phenolic and flavonoid properties of chia seeds grown in Kenya. The physical, total phenolic and flavonoid properties of chia seeds from two chia planning seasons April to August 2019 and September to December 2019 were evaluated. The physical attributes (length, width and thickness) were determined using a digital vernier calliper while proximate components were determined using AOAC standard methods. The Quencher procedure was used to determine the total phenolic and flavonoid contents. Chia seeds revealed a length of 1.82 to 2.32 (mm), a width of 1.15 to 1.31 (mm) and a thickness of 0.77 to 0.88 (mm). The percentage moisture content of chia seeds was 7.23 to 10.67, percentage of crude fat was 31.48 to 42.45, percentage of crude ash was 3.63 to 6.82, and percentage of crude fibre was 30.95 to 38.65 and percentage of crude protein was17.82 to 28.97. The total phenolic content observed for chia seeds was 0.73 to 0.87 mg GAE g-1 while total flavonoid content was 0.39 to 0.57 mg GAE g-1. The proximate components of chia seeds varied significantly (p < 0.05) based on the chia planting season while the physical properties, total phenolics and total flavonoid contents did not vary significantly.