https://dr.ur.ac.rw/handle/123456789/30 Research works by PhD students of the College of Agriculture, Animal Science and Veterinary Medicine 2026-04-14T22:36:09Z https://dr.ur.ac.rw/handle/123456789/1477 Evaluation of Performance of Five Determinate Tomato (Lycopersicon esculentum L) Varieties Cultivated in the Glasshouse and Open Field Under Environmental Conditions of Busogo, Musanze district, Rwanda Sibomana, Philippe The tomato (Solanum lycopersicum L) remains an important horticultural crop in Rwanda and its domestic demand is increasing with the population growth. However, climate change is having a significant impact on agricultural production worldwide as it causes remarkable yield losses. The knowledge of Rwandan farmers on the variety that can increase yield in different production circumstances remains also unidentified. Therefore, five determinate tomato varieties (Assila F1, Sifa F1, Roma VF, Rionex, and Cal-J) were cultivated in both glasshouse and open field at University of Rwanda, College of Agriculture, Animal Sciences and Veterinary Medicine from September 2019 to March 2020, in order to investigate their performance in both conditions. In open field, the randomized complete block design (RCBD) with three replicates was applied. The tomato varieties were grown under low temperature (11-12.5oC minimum and 20-23oC maximum). In glasshouse, the completely randomized design (CRD) with three replicates was used and tomatoes were subjected to the day and night mean temperatures of 36oC and 18oC respectively. They were evaluated on growth and yield parameters as well as their nutritional quality. For tomatoes grown under low temperatures, the highest yield was obtained on Assila F1 (35.8t/ha) with marketable yield of about 89% and Roma VF (27.4t/ha) with marketable yield of 88%. These varieties should be recommended to open field farmers in low temperature areas. However, the plant varieties grown under glasshouse conditions, scarcely produced the tomato fruits to the level that the highest yield obtained was 538.5g/plant on Sifa F1 with the average fruit weight of 30.23g. The highest yield among homozygous genotypes was Cal-J (320.4g) with the average fruit weight of 28. 27g. Nevertheless, this variety has probably acquired certain heat stress transcription factors for thermo tolerance to be considered for further scientific investigations. Master's Dissertation 2021-01-01T00:00:00Z https://dr.ur.ac.rw/handle/123456789/1245 Potential of Acacia angustissima, Leucaena pallida and Mimosa scabrella in agroforestry systems on a Rwandan Ferralsol Mukangango, Marguerite Agroforestry using coppicing legume trees and shrubs is a way to improve livestock fodder quality and soil fertility in the tropics. However, tree establishment and appropriate management are challenging, hampering their integration into agriculture and livestock systems. This thesis evaluates the biomass production by Acacia angustissima, Leucaena pallida and Mimosa scabrella legume tree species grown on a Ferralsol in Southern Rwanda, determines their effects on fodder quality and assesses the fertiliser quality of the resulting manure and its effect on a maize crop yield and the fertility status of a Rwandan Ferralsol. In field studies, biomass production and nutritive value of the three agroforestry species when subjected to 0.3 and 1.0 m cutting height were determined and the effects of micro-dosing manure, fertiliser and lime on soil properties and maize yield were examined. Higher biomass production was generally found at lower cutting height. Acacia angustissima had the highest biomass production, whereas M. scabrella was sensitive to repeated harvests. Crude protein (CP) was not affected by cutting height, but neutral detergent fibre (NDF), acid detergent fibre (ADF) and total polyphenols were higher at grater (1.0 m) cutting height. The highest CP was found in A. angustissima and the highest NDF and ADF in M. scabrella. Mixing legume leaves with Chloris gayana grass improved feed CP content, dietary mineral content and digestibility. Adding A. angustissima into C. gayana grass based feed increased the total nitrogen, organic carbon and base cation content in the manure produced. Manure application increased soil pH, soil nutrient content, soil organic carbon, soil cation exchange capacity and water-holding capacity at maize planting stations. Maize agronomic parameters and yield increased with manure micro-dosing method. Thus A. angustissima and L. pallida appear to be robust species for use in agroforestry systems with similar biophysical conditions and cutting methods to those tested in this thesis, and can be recommended to improve low-quality forage. Manure micro-dosing is a promising practice for soil fertility replenishment in crop production by smallholder farmers with limited income and access to manure. Doctoral Thesis 2019-05-20T00:00:00Z https://dr.ur.ac.rw/handle/123456789/1232 Performance of Ankole and crossbred cattle in Rwanda Manzi, Maximillian The general aim of this thesis was to evaluate how effective crossbreeding could be for increasing productivity in meat and milk production in Rwanda. This was done by assessing performance of Ankole (A) and its crossbreds with exotic breeds: Brown Swiss (B), Holstein Friesian (F), Jersey (J) and Sahiwal (S). Paper I-III were generated from records collected on growth, reproduction and milk yield of cattle genotypes from research stations and paper IV was based on survey data from farms in three agroecological zones. Birth weight for Ankole-Jersey calves were significantly lower (25.8 kg) than for the other crossbreds, which did not differ from each other (27.5-28.4 kg). Ankole-Friesian calves (AF) were heavier than all other crossbreds at weaning (182 kg vs 152-168 kg) (Paper I). In Paper II, the breed group had a significant effect on intervals from calving to first or last inseminations (CFI, CLI), calving interval (CI), and conception rate (CR). The cross AF had higher CR than the purebred Ankole and AS (78% vs 71% and 67%), and AS had lower CR than AJxS and AJ (67% vs 75% and 73%). Pure-bred Ankole (AA) had longer CFI and CLI than all crossbreds except AF and hade 54 days longer CI than all crossbreds (498 vs 445 days). In the study on milk yield (Papers III-IV), AA had the lowest average daily milk yield (2.0 L); AA also tended to have longer lactation length. Among the crossbreds, there was no significant difference in milk yield between AF, AJxS, and ASxJ (4.4-4.7 L), nor between AS and ASxS (3.3 L). Paper IV revealed significant breed effects on the average milk yield, with AF producing less milk per day (8.6 L) compared with purebred Holstein Friesian (14 L). Among zones, Eastern agroeco-logical zone recorded the highest daily milk yield, which was estimated at 14.9 L compared to 9.4, 9.2, and 8.5 L in Birunga, Central and Western agroecological zones, respectively. Generally, a crossbred of Ankole and Holstein Friesian (AF) had good growth, good conception rate, and high production, but still as long calv-ing to first insemination and calving to last insemination intervals as Ankole. Doctoral Thesis 2018-12-14T00:00:00Z https://dr.ur.ac.rw/handle/123456789/1205 Mastitis in dairy cows in Rwanda: prevalence, aetiology, antimicrobial resistance, molecular epidemiology and effects on milk quality Ndahetuye, Jean-Baptiste The milk sector in Rwanda can be made competitive through improved udder health resulting in higher milk yields. This thesis investigated prevalence and aetiology of subclinical mastitis (SCM) in dairy cows, antimicrobial resistance and molecular epidemiology of udder pathogens. Screening for SCM with California Mastitis Test (CMT) was done in 828 cows in 429 herds from five regions in Rwanda. Milk was sampled from udder quarters with CMT score ≥3. Herd bulk milk quality and safety was investigated to generate knowledge for quality control. Overall SCM prevalence was 70.4% on herd level, 66.3% on cow level and 39% on quarter level. Overall 73.9% of all cultured milk samples were bacteriologically positive. Non-aureus staphylococci (NAS) followed by Staphylococcus (S.) aureus were the predominant pathogens. Staphylococcus chromogenes, epidermidis and sciuri were the most prevalent NAS. There was a high diversity of S. aureus sequence types, with both humans and cows as possible sources. Penicillin resistance exceeded 60% in all staphylococci. Among S. aureus isolates, 83.3% were resistant to penicillin, 100% to clindamycin and 20% to tetracycline. Main risk factors for SCM with implications on management routines included housing of cows in individual cattle kraal and on earthen floor, poor hygiene (hands, cows and milking area), absence of foremilk stripping, increasing stage of lactation, Holstein breed, lack of calf suckling and of feeding after milking. Total bacterial count and somatic cell count was high in milk from farms and milk collection centers, which indicate poor udder health and hygiene and contamination along the transport chain. Presence of Escherichia coli, Salmonella spp. and brucella antibodies in milk was common. Antimicrobial residues in milk was uncommon. In conclusion, SCM is common in dairy herds in Rwanda and the majority of causative pathogens exhibited penicillin resistance. The high microbial load has implications for milk quality, processability and public health. The high genetic diversity of S. aureus should be considered in future studies of disease spread. A mastitis control plan is recommended. Doctoral Thesis 2019-11-27T00:00:00Z