College of Agriculture

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The College of Agriculture is committed to advancing agricultural education, research, and community service. It serves as a center for knowledge creation and dissemination in crop science, animal production, natural resource management, and sustainable agriculture.

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    ESTIMATION OF GENETIC AND PHENOTYPIC PARAMETERS FOR MILK PRODUCTION AND REPRODUCTION TRAITS IN A DEVELOPING SYNTHETIC DAIRY CATTLE BREED AT HOLETA AGRICULTURAL RESEARCH CENTER, ETHIOPIA
    (Hawassa University College of Agriculture, 2025) ASAMENEW AYALEW
    This study was carried out to estimate genetic and phenotypic parameters for milk production and reproduction traits of synthetic dairy cattle breed development program being implemented at Holeta research center dairy farm. Data collected from 1995 through 2024 on lactation milk yield, lactation length ,daily milk yield, age at first service, age at first calving, and calving interval from experiments targeted to develop synthetic breed at Holeta Agricultural Research Center dairy herd were used for this study. The GLM procedures of SAS software were used to estimate the effect of fixed effects such as year, season and parity while regression analysis was performed to estimate crossbreeding parameters (additive, heterosis and recombination effects). Genetic components including variance covariance estimates were analyzed using WOMBAT software. A univariate mixed model for genetic Parameters and Multiple Regression Model for crossbreeding parameters was used for data analysis. The performance of dairy cattle affected by genetic and non-genetic factors. The result of fixed effects (year and genetic group) analysis showed that a significant (p<0.0001) differences in all productive and reproductive traits. Correspondingly, productive traits (LMY and DMY) and reproductive (CI) traits were also significantly (p<0.0001) influenced by parity. The traits, lactation milk yield, were sensitive to seasonal variation. The overall least squares means for lactation milk yield (LMY), daily milk yield (DMY), lactation length (LL), age at first service (AFS), age at first calving (AFC) and, calving interval(CI)were 2140.61 ± 32.92kg, 6.89 ± 0.07kg, 316.54 ± 3.31days, 33.56 ± 0.63months, 42.78 ± 0.63months and, 469.01 ± 7.03days, respectively. Additive genetic effects were much larger than for the non-significant negative value of heterosis effect of lactation milk yield (3728 ± 139.39 kg of additive and -81.65 ± 97.98 kg of heterosis).The cross breeds were -21.51± 29.19 days, -2.29 ± 3.12 months, and -2.23 ± 3.12 months, reduced for CI, AFS and, AFC due to the additive effect of Friesian gene. Estimation of heritability for productive traits (LMY, DMY and LL) were 0.180 ± 1.00, 0.235 ± 0.053 and 0.219 ± 0.077, respectively and reproductive traits (AFS, AFC, and CI) 0.0798 ±0.034, 0.080 ±0.033and 0.180 ± 0.042, in respective order. The current result indicated that repeatability values of productive traits 0.589 ± 1.00 for LMY, 0.491± 0.227 for DMY, 0.735± 0.151 for LL, and0.23±0.01 for CI. The current study indicated that the direct genetic correlation between productive traits were positive and ranged from very weak (0.141 ± 0.073) to very strong (0.854 ± 0.304) genetic correlations. From the current study high correlation was observed in between LMY and LL (0.854 ± 0.304). The current study indicated that positive genetic correlation ranged from very weak to weak genetic correlation among reproductive traits. AFS-AFC (0.228 ± 0.172), AFS-CI (0.181 ± 0.194), AFC-CI (0.063 ± 0.02).The present study indicated that the genetic correlation among productive and reproductive traits was closely related with each other in some traits. Strong genetic correlation looked between CI-LL (0.785 ± 0.074), moderate genetic correlation between CI-LMY and AFC-LL (0.428 ± 0.098, and 0.40 ± 0.107), respectively. Thus, based on the study's findings, it was feasible to draw the conclusion that proper parental line selection and crossing should be used to create next-generation calves and improve the farm's overall management system.
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    SURVEY OF ETHIOPIAN PEPPER MOTTLE VIRUSES IN THE CENTRAL RIFT VALLEY OF ETHIOPIA AND EVALUATION OF NETTING DURATION AS MANAGEMENT OPTION
    (Hawassa University College of Agriculture, 2018) KUMSA DIDA FAYE
    Ethiopian pepper mottle virus is one of the major constraints of pepper production in the central rift valley region of Ethiopia. The present study was conducted to assess the prevalence of Ethiopian pepper mottle virus in the region and to determine optimum netting duration for efficient protection of pepper from vector infestation and subsequent viral infection. For this purpose, field survey and an experiment was carried out in the central rift valley of Ethiopia. The survey was conducted on 60 pepper fields in three districts i.e. Butajira, Meki and Ziway districts. Data were collected on the incidence of viral disease, plant height and number of pods per plant. In addition, field experiments were carried out at Hawassa and Meki to assess the efficacy of netting duration against aphid vectors and viral diseases. Data were collected on the number of aphid populations, virus incidence, and pepper growth parameters and yield. Visual inspection of the surveyed fields revealed that almost all the pepper fields (99.6%) had viral diseases. Viral disease incidence ranged from 52.8% in Ziway district to 68.6% in Butajira district. Furthermore, significant variations at (p<0.01) were observed between treatments of the field experiments in terms of aphid infestation, virus incidence and pepper yield. Covering of plots with net for up to 60 or more days after transplanting reduced aphids’ populationper plant by a greater margin (61.8%-76.9% in Hawassa; 52.4-67% in Meki) and virus incidence by 48%-60.8% in Hawassa and 38.6%-48.5% in Meki as compared to the control plots. Total and marketable yields were significantly higher in plots protected by net for up to 60 days or more after transplanting while unmarketable yields were low in those plots. Low virus incidence and aphids’ population in plots covered by net up to 60 days after transplanting and longer resulted in increased yields by 44 %-55 % in Hawassa and 38 %-49.5 % in Meki as compared to the control plots. Unmarketable yield was positively correlated (p<0.001) with aphids population and virus incidence while total and marketable yields were negatively correlated with aphids population and virus incidence. The current results suggest the need to apply control measures at early growth stages to effectively protect pepper plants from aphids and associated viruses.
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    SOME PHYISICAL AND CHEMICAL PROPERTIES OF CASHMERE TYPE FIBERS FROM LONG HAIRED ARSI BALE GOATS
    (Hawassa University College of Agriculture, 2020) BALI TESFAYE SORA
    A study was carried out to access the fleece quality parameters of long haired Arsi Bale goats which are reared at Dinsho and Agarfa District of Oromia regional state. The long haired Arsi Bale goats are raised in the cold areas of Bale zone and have very long hairs and warm undercoat. Earlier studies have indicated that the goats are raised primarily for their skin and pelt which are used as saddle cover and also for covering of furniture’s in the home. This study was carried out to access the physical and chemical quality of the fleece obtained from healthy bucks and does reared in the selected kebeles of Dinsho and Agarfa District. Proportional sampling method was used to identify the bucks and does. Based on the same 21 bucks from Dinsho district and 17 from Agarfa district and 29 does from Dinsho district and 33 from Agarfa district were selected. The age of the bucks was determined by their dentition and only adult (>1 year old) goats were selected for the fleece. The fleeces were combed from the neck region of the healthy goats and then they were packed in plastic bags before being transported to the laboratory at School of Animal and Range Science laboratory. The fleece were studied for staple length, numbers of crimps/inch, numbers of hairy, hetero and fine fibers, average diameter of the hetero, hairy and fine fibers (in micron). The chemical properties of the fleece included the percentages of ash, wax, scouring yield and burr. The numbers of fleece and their diameter was accessed using a digital microscope at 40X magnification. The data were analyzed for the effects of location and sex on the fleece quality parameters. The findings for the bucks indicated that there were differences (P<0.05) only in crimp, numbers of pure fibers and scouring yield of the bucks reared in the two locations. While among the does there were differences P<0.05 in staple length, crimp, fiber diameters (hairy, hetero and pure), in percentages of ash, scouring yield and wax of the bucks reared in the two Districts. The study also shows that there was a wide variation in the numbers of pure, hetero and hairy fleece while, differences in the fiber diameter were minimum. The study pertaining to the effects of sex further indicated that there were differences in the fiber wax parameter among the bucks and does raised at Dinsho. In Agarfa district there were differences (P<0.05) in staple length, numbers of hairy fibers, hetero and pure fibers, hetero and pure fiber diameters. The within sex differences due to location can be due to the adaptability of the goats to the locations and also due to crossings of the bucks/does with the short haired Arsi Bale goats. The differences between the sexes within locations can be ascribed due to sexual dimporphism and also the traditional breeding objectives which differ across the sexes. There was a possibility of selection within the genotypes for the parameters studied and thereafter further improving the same.
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    ECOLOGY AND INSECTICIDE RESISTANCE MANAGEMENT OF THRIPS (THYSANOPTERA: THRIPIDAE) ON ONION (Allium cepa L.) IN THE RIFT VALLEY OF ETHIOPIA
    (Hawassa University College of Agriculture, 2020) BELETE NEGASH
    Ecology and Insecticide Resistance Management of Thrips (Thysanoptera: Thripidae) on Onion (Allium cepa L.) in the Rift Valley of Ethiopia Belete Negash1 , Ferdu Azerefegne1 and Gashawbeza Ayalew2 1Hawassa University, College of Agriculture, Hawassa, Ethiopia 2 Ethiopian Institute of Agricultural Research, Melkassa Research Center, Adama, Ethiopia ABSTRACT Decline in efficacy of registered insecticides to control thrips (Thysanoptera: Thripidae) on onion in Ethiopia stimulated studies on insecticide resistance, ecology and management of thrips on onion in the major onion production belt of the Central Rift Valley of Ethiopia (CRV). Several studies including farmers‟ insecticide use practices against thrips on onion, species composition and abundance, seasonal abundance of thrips and their effect on yield, insecticides resistance detection and management were conducted from 2015 to 2017. Diazinon, dimethoate, profenofos, lambda-cyhalothrin and spinetoram were widely used for thrips control on onion in the surveyed areas. Type and frequency application of insecticides use were different among the locations. Insecticide application frequencies were higher at Meki and Melkassa than in Werer areas. All the onion fields visited during the survey were infested by two thrips species namely, the western flower thrips, Frankliniella occidentalis (Pergande) and the onion thrips, Thrips tabaci (Lindeman). Thrips species compositions vary with locations. While, T. tabaci was dominant in Werer and Melkassa areas. The F. occidentalis thrips species was dominant at Meki location. Thrips population was higher during mid-growth stage of onion, 50 to 64 days after transplanting, than early and late growth stages in cool dry (October–January), hot dry (February – may) and rainy (June – September) growing seasons. Significantly lower thrips population recorded in the rainy season than the cool dry and hot dry seasons. Onion growth stage, growing seasons and sunshine hours were important factors for predicting thrips numbers. Cool and rainfall seasons significantly negative correlated with thrips numbers, while it was positively correlated with the onion growth stage, maximum temperature and sunshine hours. Thrips number was significantly greater on untreated plots than insecticide treated plots except in the rainy season. Higher percent yield losses were recorded on planting made in cool dry and hot dry 2 seasons in both years than rainy season with 8.24 to 40.17% yield losses. Commonly used insecticides on thrips were evaluated for their efficacy both in field and laboratory condition. Plots treated with spinosad, spinetoram, and imidacloprid resulted in better control, which was comparable higher marketable yield of onion both in cool and hot dry seasons. While, alphacypermethrin, diazinon, neem and λ-cyhalothrin insecticides treated plots poorly performed in both seasons and had lower marketable yield. Performances of dimethoate and profenofos were intermediate with the intermediate yield gains over the control under field condition. Laboratory bioassay confirmed that the poor efficacy of λ –cyhalothrin and diazinon under field conditions was due to thrips resistance to these insecticides. Higher level of resistance was recorded to λ – cyhalothrin and diazinon in Meki and Melkassa collected thrips populations, whereas no resistances to profenofos, dimethoate and spinetoram insecticides in all tested thrips populations were found. From insecticides resistance management studies, the sequential application of the more effective insecticides, imidacloprid and spinetoram, followed by less effective insecticide λ-cyhalothrin resulted in better control with higher economic return. Adding a penetrating surfactant improved the efficacy of insecticides compared to those without a penetrating surfactant in both seasons. Onion growers will continue to rely on insecticides as part of thrips management. Hence screening of new molecules periodically to identify effective insecticides and deploying a resistance management strategy through, among others, rotational application should form integral component in the integrated management of thrips (IPM) on onion. Studies on non-chemical control methods including cultural such as intercropping with other vegetables, host plant resistance should be conducted with the aim of strengthen thrips IPM