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...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.展开更多
Longevity and stay ability are parameters in any breeding programme. </span><span style="font-family:Verdana;">The </span><span style="font-family:Verdana;">Overstaying of a...Longevity and stay ability are parameters in any breeding programme. </span><span style="font-family:Verdana;">The </span><span style="font-family:Verdana;">Overstaying of any animal </span><span style="font-family:Verdana;">o</span><span style="font-family:Verdana;">n a farm has got negative effects </span><span style="font-family:Verdana;">on</span><span style="font-family:Verdana;"> the farmer. Short stay also means early exit of good animal</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> 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</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> longevity is taken purely on </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">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 </span><span style="font-family:Verdana;">provided genetic and phenotypic parameters to enable </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">inclusion of longevity in the breeding objective for the Sahiwal cattle improvement pro</span><span style="font-family:Verdana;">gramme.展开更多
<span style="font-family:Verdana;">Direct selection for longevity results in improved health and fitness and even milk production of cows. However, longevity is lowly heritable and phenotypic informati...<span style="font-family:Verdana;">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 <span style="font-family:Verdana;white-space:normal;">-</span>0.96 ± 0.06, <span style="font-family:Verdana;white-space:normal;">-</span>0.06 ± 0.03 to <span style="font-family:Verdana;white-space:normal;">-</span>0.67 ± 0.08 and <span style="font-family:Verdana;white-space:normal;">-</span>0.02 ± 0.02 to <span style="font-family:Verdana;white-space:normal;">-</span>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 <span style="font-family:Verdana;white-space:normal;">-</span>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. </span><span style="font-family:Verdana;">Therefore, first lactation milk yield and age at first calving could</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> therefore</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> be used to indirectly select for longevity.</span>展开更多
文摘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.
文摘Longevity and stay ability are parameters in any breeding programme. </span><span style="font-family:Verdana;">The </span><span style="font-family:Verdana;">Overstaying of any animal </span><span style="font-family:Verdana;">o</span><span style="font-family:Verdana;">n a farm has got negative effects </span><span style="font-family:Verdana;">on</span><span style="font-family:Verdana;"> the farmer. Short stay also means early exit of good animal</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> 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</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> longevity is taken purely on </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">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 </span><span style="font-family:Verdana;">provided genetic and phenotypic parameters to enable </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">inclusion of longevity in the breeding objective for the Sahiwal cattle improvement pro</span><span style="font-family:Verdana;">gramme.
文摘<span style="font-family:Verdana;">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 <span style="font-family:Verdana;white-space:normal;">-</span>0.96 ± 0.06, <span style="font-family:Verdana;white-space:normal;">-</span>0.06 ± 0.03 to <span style="font-family:Verdana;white-space:normal;">-</span>0.67 ± 0.08 and <span style="font-family:Verdana;white-space:normal;">-</span>0.02 ± 0.02 to <span style="font-family:Verdana;white-space:normal;">-</span>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 <span style="font-family:Verdana;white-space:normal;">-</span>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. </span><span style="font-family:Verdana;">Therefore, first lactation milk yield and age at first calving could</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> therefore</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> be used to indirectly select for longevity.</span>