So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Drought stress linked with climate change is one of the major constraints faced by common bean farmers in Africa and elsewhere. Mitigating this constraint requires the selection of resilient varieties that withstand drought threats to common bean production. This study assessed the drought response of 64 small red-seeded genotypes of common bean grown in a lattice design replicated twice under contrasting moisture regimes, terminal drought stress and non-stress, in Ethiopia during the dry season from November 2014 to March 2015. Multiple plant traits associated with drought were assessed for their contribution to drought adaptation of the genotypes. Drought stress determined by a drought intensity index was moderate (0.3). All the assessed traits showed significantly different genotypic responses under drought stress and non-stress conditions. Eleven genotypes significantly (P ≤ 0.05) outperformed the drought check cultivar under both drought stress and non-stress conditions in seed yielding potential. Seed yield showed positive and significant correlations with chlorophyll meter reading, vertical root pulling resistance force, number of pods per plant, and seeds per pod under both soil moisture regimes, indicating their potential use in selection of genotypes yielding well under drought stress and non-stress conditions. Clustering analysis using Mahalanobis distance grouped the genotypes into four groups showing high and significant inter-cluster distance, suggesting that hybridization between drought-adapted parents from the groups will provide the maximum genetic recombination for drought tolerance in subsequent generations.

/pdf/evaluation-of-common-bean-phaseolus-vulgaris-l-genotypes-for-5f1krgc44w.pdf

Evaluation of common bean (Phaseolus vulgaris L.) genotypes for drought stress adaptation in Ethiopia

The huge livestock resources of the country could not be used to its potential due to lack of good-quality feed throughout the year. Consequently, finding alternative feed supplements for livestock is an important step to sustain livestock production in the country. Ficus thonningii leaf is one of the potential feed resources for ruminants in the area. The experiment was conducted with the objective of evaluating the nutrient intake, digestibility and growth performance of local lambs fed natural pasture hay (NPH)-based diet supplemented with graded levels of Ficus thonningii dried leaves (FTL) and determining of the optimum level for replacing of concentrate mixture (CM). Twenty intact male yearling Washera lambs with initial body weight of 17.06 + 1.43 (mean + SE) kg were used in experiment. The experiment was conducted using randomized complete block design having four replications with five dietary treatments. The treatments were T1 = NPH + 0 g FTL +215 g CM; T2 = NPH + 112.5 g FTL +161.25 gCM; T3 = NPH + 225 g FTL +107.5 g CM; T4 = NPH + 337.5 g FTL + 53.75 g CM; and T5 = NPH + 450 g FTL +0 g CM. Data were analyzed using the general linear model procedures of SAS (version 9.3; 2002). The results showed that FTL are a good source of crude protein (CP) (126.9 g/KgDM) and fibers (377–426 g/Kg DM). Results also showed that supplementation of higher-level FTL significantly (P   0.05) observed in CP and ME intakes among treatments. Increasing level of FTL supplementation, however, reduced significantly (P   0.05) differences were observed in lambs assigned up to 75% replacement of CM. The lowest performance was observed in sole FTL supplementation (T5), despite increased nutrients intake. It was concluded that indigenous fodder tree Ficus thonningii leaves could serve as alternative CP supplement in NPH-based feeding of Washera sheep and can be used to replace CM up to 75% to improve performance.

/pdf/nutrient-intake-digestibility-and-growth-performance-of-33l8rkbt6z.pdf

Nutrient intake, digestibility and growth performance of Washera lambs fed natural pasture hay supplemented with graded levels of Ficus thonningii ( Chibha ) leaves as replacement for concentrate mixture

A study was conducted to document how smallholder farmers in Ethiopia utilize desho grass ( Pennisetum pedicellatum ) and explain the determinants of alternative and competing uses of the grass. The study was conducted using a semi-structured questionnaire for 240 farmers in the districts of Burie Zuria and Doyogena, complemented with input from key informants and secondary data. The dependent variables tested were the use of desho grass as a feed, multipurpose uses of the grass and types of livestock fed. To test the effect of the explanatory variables on the dependent variables, separate univariate Probit models were used. Although the majority of respondents can read and write, about 23% of respondents were illiterate. The average desho grass-producing farmer in the sample owned 0.95 ha of farmland and 3.56 tropical livestock units; average household size was 6.5 people with a household head who was typically male (91% of households). Eighty percent of respondents in Burie Zuria and all respondents in Doyogena district depended solely on rain for desho grass production. Fifty-eight percent in Burie Zuria and 65% in Doyogena district applied either manure or artificial fertilizer to the grass. Weeding of desho grass was not practiced by any respondents in either district. Sixty percent of farmers used desho grass as a feed and 35% used it for more than a single purpose. Forty-two percent of farmers who fed desho grass did so to only lactating cattle, 3% fed it to small ruminants and 53% fed it to all livestock species. There were significant negative correlations (P<0.01) between both experience in production of desho grass and access to training in its production and utilization, and its utilization as a feed. Seventy percent of farmers in Burie Zuria and 13% in Doyogena have received training in desho grass production. To expand the utilization of the grass to as many farmers as possible, further training should be provided. A multi-faceted approach would be needed for the 23% of illiterate farmers over the 2 districts. Keywords : Cut-and-carry, lactating animals, multipurpose, Probit models. DOI: 10.17138/TGFT(4)112-121

Determinants of the utilization of desho grass ( Pennisetum pedicellatum ) by farmers in Ethiopia

A total of 3460 lactation records that represented 1059 dairy Holstein-Friesian cows were used in the present study that aimed to estimate genetic parameters such as heritability, genetic correlations, phenotypic correlations and genetic trends for some productive and reproductive traits. Studied traits were total milk yield, days in milk, fat %, protein %, dry period, age at first calving, number of services per conception, days open and calving interval. Data were collected from Egyptian Copenhagen Company in Alexandria-Cairo desert road for cows calved from 1998 to 2010. Least square analysis of mixed sire model was used in analysis using Harvey (1990) program. Heritability estimates were high for all traits and very high for fat and protein % that exceeded 0.83 in two lactations. Genetic correlations were higher than phenotypic correlations and were high especially among production traits. Regression coefficients of genetic trends were positive for all studied traits except for days in milk and days open (in second lactation) and age at first calving. Generally, the current results showed genetic improvement of most of traits that reflect the efficiency of selection programs.

https://scvmj.journals.ekb.eg/article_78285_74f0a170a39b91550c5a8c4581c18137.pdf

Estimation of heritabilities, genetic correlations, phenotypic correlations and genetic trends for production and reproduction traits of Holstein-Friesian dairy cattle using sire model

A total of 1979 lactation records from 550 selected crossbred dairy cows that born between 1974 and 2005 were used to estimate annual genetic and environmental trends in milk production and reproduction traits at Holetta Agricultural Research Center, Ethiopia. Annual genetic and environmental trends were estimated by regressing BLUP estimated breeding value on year of birth. Variance components and genetic parameters were estimated using univariate analysis of individual animal model based on restricted maximum likelihood procedures. Annual genetic trends were -3.384 days, -8.00 kg and -5.96 kg, -0.26 months, -0.29 months and -0.88 days, for lactation length (LL), lactation milk yield (LMY), adjusted 305 milk yield (305-days MY), age at puberty (APU), age at first calving (AFC) and calving interval (CI), respectively. Environmental trends for LMY was positive (6.717 kg) and was in the desired direction. Heritability estimates were 0.14, 0.44, 0.39, 0.38, 0.40 and 0.17 for LL, LMY, 305-d MY, APU, AFC and CI, respectively. Negative genetic trends in all milk production traits reflect ineffective selection program and/or lack of using sires that have positive breeding values. The result from the environmental trends shows substantial improvement in the management practices over time. Contrasting directions in genetic and environmental trends reflect ineffective breeding objectives. This warrants reconsideration of the existing breeding program in the country.

	 

	Key words: Genetic trends, environmental trends, genetic parameters, breeding objectives, variance components.

https://www.africaneditors.org/journal/JCAB/full-text-pdf/84812-120692

Genetic and environmental trends in the long-term dairy cattle genetic improvement programmes in the central tropical highlands of Ethiopia.

This study was conducted to investigate feed resource availability in association with livestock production in the Central Rift Valley of Ethiopia. Random sampling was used to select target farms. A total of 60 livestock owners were selected from two districts namely Admi Tullu Jidokombolcha and Dugda Bora both in the central Rift Valley. Structured questionnaire, focused group discussions, secondary data sources and field observations were employed to generate data on household structure, farm size, land use pattern, herd size, herd composition, purpose of livestock raising,  major crops grown, crop grain yield, livestock feed types and quantity of total feed. The results of the study indicated that natural pastures and crop residues were the main basal diets in both districts, with crop residues supplying the largest proportion of dry matter.The total livestock population is estimated as 15 and 16 TLU in Adami Tullu Jidokombolcha and Dugda Bora districts, respectively. The total annual DM production met 81 and 80% of the total livestock requirement per annum per farm in Admi Tullu Jidokombolcha and Dugda Bora districts, respectively. From the current study, it was concluded that the available basal roughage feeds were not sufficient to meet livestock dry matter requirement. Alternative means of feed production and supply should be sought with the involvement of all stakeholders.

	Key words: Dry matter, feed resources, livestock.

https://www.academicjournals.org/article/article1393341008_Wondatir and Mekasha.pdf

Feed resources availability and livestock production in the central rift valley of Ethiopia

The study was conducted to assess the performance of dairy cattle in relation with feed availability and quality in selected peri-urban of Debre Birhan, Jimma and Sebeta areas of Ethiopia. Structured questionnaire, secondary data sources, field observations and laboratory analysis were employed to generate data. A total of 60 farmers (Debre Birhan=20, Jimma=20 and Sebeta=20) were randomly selected for the study. The overall estimated mean lactation length of cows was 296.5±8.7 days and was not different (P>0.05) among sites. The overall estimated mean age of heifers at first service was 27.5±1.0 months and age at first calving was 36.8±1.0 months and differed (P<0.001) considerably among the study sites. The result of the study indicated that grass hay was the main basal diet in all study areas. Laboratory analysis of major feed resources indicated that hay had Crude Protein (CP) content of 6.1% and crop residues varied from 3.1 to 6.7%. In addition, crop residues had lower digestibility (48%), its energy value ranged from 6.5 to 7.9 MJ/kg dry matter (DM). Wheat bran, and molasses had Metabolizable Energy (ME) content of 13.2 and 12.5 MJ/kg DM, respectively. Brewery wet grains had lower CP (27%) than cottonseed cake (42%) and enough seedcake (35%). Annual feed balance estimation revealed that the total estimated available feed supply met 83% of the maintenance DM requirement of livestock per farm per year while, the total estimated CP and ME were in accordance with the livestock requirement merely for maintenance. Therefore, from the current study it was concluded that the quality of available basal roughage feeds is generally low and strategic supplementation of protein and energy rich feeds should be required. Furthermore, optional feeds like brewery wet grains and other non-conventional feed resources should be further considered.

	 

	Key words: Age at first service, calving interval, crude protein, daily milk yield, days open, feed supply, feed quality, lactation length, metabolizable energy.

Zewdie Wondatir

Papers

Genetic and environmental trends in the long-term dairy cattle genetic improvement programmes in the central tropical highlands of Ethiopia.

Feed resources availability and livestock production in the central rift valley of Ethiopia

Assessment of productive and reproductive performance of dairy cattle nexus with feed availability in selected peri-urban areas of Ethiopia

Peri-urban dairy production system in relation with feed availability in the highlands of Ethiopia.