Department of Animal Science

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    Impact Of Late-Stage Hypoxic Stimulation And Layer Breeder Age On Embryonic Development, Hatching And Chick Quality.
    (Elsevier Inc., 2024-12-24) Agbehadzi, R.K.; Adjei-Mensah, B.; et al.
    The present study examined the effects of breeder age and oxygen (O₂) concentrations during the late chorioallantoic membrane (CAM) growth stage on embryo development, hatching dynamics, chick quality, bone mineralization and hatchability. A total of 1200 eggs from 33- and 50-week-old ISA layer breeders, weighing 53.85 g and 60.42 g on average respectively, were incubated at 37.7°C and 56 % relative humidity. From embryonic day (ED) 13 to 15, experimental eggs were exposed to hypoxia (15 % or 17 % O₂ for 1 hr/day) while the control was at 21 % O₂. Results showed significant interactions (p = 0.040) between breeder age and oxygen level, with embryos exposed to 15 % and 17 % O₂ exhibiting slower growth by ED 17. However, embryo weight at internal pipping (IP) was unaffected (p > 0.05). At hatch, chick weights were higher in hypoxic groups due to increased yolk sac retention (p = 0.024), while yolk-free weights were influenced only by breeder age (p < 0.001). Hypoxia at 15 % O₂ reduced chick length, toe length, and tibia parameters (p < 0.05), likely due to impaired calcium and phosphorus absorption. Embryos exposed to 15 % O2 had longer internal and external pipping events, delaying hatch time. Embryonic mortality was highest (p < 0.001) at 15 % O₂, contributing to the reduced hatch of fertile eggs. This research demonstrates that controlled hypoxic conditions can slow embryonic development, conserve yolk nutrients, improve organ maturation and chick weight across breeder ages.
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    organ histology
    (Journal of Applied Poultry Research, 2024) Agbehadzi, R. K .; Adjei-Mensah, B.; Sasu, P.; Bilalissi, A.; Kpomasse, C.C.; N’nanle, O.; Hamidu, J. A.; Tona, K.
    This study examines how the combination of layer breeder age and oxygen concentration in the incubator impacts Chorioallantoic (CAM) vascularization, embryo and chick organs, blood profiles, and organ histology at hatch. Nine hundred (900) eggs from 33 to 50 wk ISA breeders were incubated at different O2 levels (15%, 17%, and 21%). Results showed signifi cant interactions between breeder age and oxygen levels, affecting liver and heart weights, blood indices, and CAM vascularity. Hypoxic conditions led to adaptive changes in embryonic organs, with notable differences between breeder age groups, suggesting that mild hypoxia can influence compensatory growth, depending on exposure stages.
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    Feed the Future Innovation Lab for Genomics to Improve Poultry: a holistic approach to improve indigenous chicken production focusing on resilience to Newcastle disease
    (World's Poultry Science Journal, 2024) Zhou, H.; Baltenweck, I.; Kayang, B.B.
    Small-scale poultry production in Africa plays a significant role in alleviating malnutrition and poverty in rural communities. Global climate change and infectious poultry disease such as Newcastle disease (ND) have had tremendous negative impact on poultry production and health due to limited biosecurity, cold chain, and inadequate extension service. Genetic selection for enhanced resis tance to ND virus (NDV) offers a promising complementary approach to vaccination and biosecurity in addressing constraints in village production systems. The Feed the Future Innovation Lab for Genomics to Improve Poultry (GIP IL) has led an effort on the identification of genetic markers, genes and signalling pathways associated with enhanced resistance to NDV by conducting NDV challenging experiments in diverse inbred, commercial, and African indigenous chickens. The GIP IL developed a comprehensive genetic selection platform focusing on improved survival time and reduced virus shedding in the face of NDV infection and on enhanced growth rate and egg production. The programme applied the platform for genetic selection and breeding of indigen ous chickens through velogenic NDV natural exposure trials. To improve our understanding of the epidemiology of NDV in Africa, we characterised circulating strains of the virus in Ghana and Tanzania and identified NDV risk factors among local chickens. These data contribute to a body of knowledge useful for guiding disease control efforts, informing vaccine strategies, enhancing biosecurity, and contributing to our overall understanding of NDV dynamics. To gauge the demand for genetically improved
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    Population Structure and Genomic Characterisation of the Ashanti Dwarf Pig of Ghana
    (Animals, 2024) Aryee, S.N.D.; Owusu-Adjei, D.; Osei-Amponsah, R.; et al.
    There is still limited information on the genomic structure and genetic diversity of African pigs. Genetic diversity studies can contribute significantly to the genetic improvement and conser vation of African pigs. This study presents a genetic diversity analysis and population structure of pig breeds in Ghana, with a focus on the Ashanti Dwarf pig (ADP), an indigenous pig breed of Ghana. A total of 167 pigs sampled in Ghana and populations consisting of Ashanti Dwarf pigs (n = 106), exotics (mostly European pigs) (n = 11), crosses (between indigenous and exotic breeds) (n = 44), and unknown breeds (nondescript) (n = 6) were genotyped using Porcine SNP60K BeadChip. Moderate heterozygosity levels, ranging from 0.28 for Ashanti Dwarf pigs to 0.31 for exotic pigs (mostly European pigs), were observed. Principal component analysis of the pig populations within Ghana resulted in two distinct clusters of pigs: (i) Northern and (ii) Southern regional clusters. The PCA based on breed also resulted in four clusters: (i) ADPs; (ii) exotics (iii) crossbreeds between ADP and exotics; (iv) unknown breed types. The PCA demonstrated that the clustering was influenced by genetics, geographical location, production systems, and practices. ADMIXTURE-based analysis also showed that the populations within Ghana are admixed. FST analysis revealed SNPs associated with QTLs for traits such as disease resilience and growth among ADP populations within the different regional and ecological zones of Ghana.
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    Genetic architecture of body weight, carcass, and internal organs traits of Ghanaian local chickens
    (Frontiers in Front. Genetics, 2024) Kanlisi, R.A.; Amuzu-Aweh, E.N.; Naazie, A.; et al.
    Information on the genetic architecture of the production traits of indigenous African chicken is limited. We performed a genome-wide association study using imputed Affymetrix Axiom® 600K SNP-chip genotypes on 1,113 chickens from three agroecological zones of Ghana. After quality control, a total of 382,240 SNPs remained. Variance components and heritabilities for some growth, carcass and internal organ traits were estimated. The genetic and phenotypic correlations among these traits were also estimated. The estimated heritabilities of body weight at week 22 (BW22), average daily gain (ADG), dressed weight, breast weight, thigh weight, wing weight, drumstick weight, and neck weight were high and ranged from 0.50 to 0.69. Estimates of heritabilities for head weight, shank weight, and gizzard weight were moderate (0.31–0.35) while those of liver weight, back weight, dressing percentage, and heart weight were low (0.13–0.21). The estimated heritabilities of dressed weight, breast weight, wing weight, drumstick weight, neck weight, shank weight, and gizzard weight, corrected for BW22, were moderate (0.29–0.38), while the remaining traits had low heritability estimates (0.13–0.21). A total of 58 1-Mb SNP windows on chromosomes 1, 2, 4, 5, 6, 7, 8, 9, 13, 18, and 33 each explained more than 1% of the genetic variance for at least one of these traits. These genomic regions contained many genes previously reported to have effects on growth, carcass, and internal organ traits of chickens, including EMX2, CALCUL1, ACVR1B, CACNB1, RB1, MLNR, FOXO1, NCARPG, LCORL, LAP3, LDB2, KPNA3, and CAB39L. The moderate to high heritability estimates and high positive genetic correlations suggest that BW22, ADG, dressed weight, breast weight, thigh weight, wing weight, drumstick weight, and neck weight could be improved through selective breeding
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    Dorper sheep in Africa: A review of their use and performance in different environments
    (CABI Reviews, 2023) Ojango, J.M.K.; Okpek, M.; Osei-Amponsah, R.; et al.
    The Dorper breed developed in South Africa is used either as a pure breed or crossbred with existing indigenous breeds by many countries across the African continent to improve sheep production. This article presents documented information on the adoption, use, and performance of Dorper sheep across the continent of Africa and opportunities for their more sustainable production under the changing climatic conditions in Africa. Apart from the well-documented information on the Dorper sheep in South Africa, published information on the performance of the sheep is mainly from Eastern Africa. Most countries initially retained purebred Dorpers in nationally owned institutions for multiplication and crossbreeding trials with different indigenous breeds prior to distributing the crossbreds to diverse livestock keepers. The offspring produced through crossbreeding programs with the Dorper have better growth rates than indigenous breeds in the different countries; however, the performance of Dorper sheep in South Africa has not been achieved in any of the other countries. Genomic studies including Dorper sheep have identified regions of interest for resistance to brucellosis and Mycoplasma ovipneumonia that imply adaptability to challenging environments within Dorper sheep. Unfortunately, limitations in systems for guided breeding and monitoring of sheep productivity in Africa have resulted in haphazard crossbreeding of the Dorper. Targeted efforts are required across the different countries to develop breeding programs for improving locally adapted Dorper sheep populations and their crosses with indigenous breeds. New science and technologies need to be innovatively packaged and used to identify and propagate more productive and resilient Dorper and Dorper-based breed-types for the increasingly challenging tropical African range environments
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    Impact of heat stress on ruminant livestock production and meat quality, and strategies for amelioration
    (Animal Frontiers, 2023) Chauhan, S.S.; Zhang, M.; Osei-Amponsah, R.; et al.
    Climate change will continue to accentuate the negative impact of heat stress (HS) on ruminant livestock production, compromising animal welfare and meat quality. • Mitigation strategies, including providing shade on farms, modifications of animal housing (heat extractors, fans, water sprinklers, and cool drinking water), and nutritional interventions, are important short-term measures to reduce the negative effects of HS. • Climate-smart breeding for thermotolerance and matching of adapted ruminant breeds to appropriate production systems should be considered for more sustainable livestock production systems.
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    Spatial variability of herbage yield, grazing capacity and plant diversity in a tropical savannah rangeland ecosystem
    (African Journal of Range & Forage Science, 2023) Anane, N.D.; Ayizanga, X.; Sarkwa, F.O.; et al
    To improve ruminant livestock production, evaluation of rangelands must be a routine. Rangeland evaluation gives information about the vegetation structure, biomass yield and quality. The Guinea savannah rangelands of Ghana lack research that characterises the spatial variability of herbage yield and quality. It was hypothesised that there is spatial heterogeneity in herbage yield, grazing capacity and plant diversity in the Guinea savannah rangelands of Ghana. The objective was to evaluate the spatial structure of herbage production and grazing capacity in the Guinea savannah rangelands of Ghana for sustainable livestock production. Data were collected from 105 sampling sites and integrated into geo-statistics, using ordinary kriging interpolation to generate herbage yield and grazing capacity estimates. Herbage yield and grazing capacity ranged from 0.63 t ha−1 to 13.43 t ha−1 and 0.18 LU ha−1 to 3.79 LU ha−1 respectively. The root mean square error and the average standard error values were close (2.38 and 2.51 respectively for herbage yield and 0.67 and 0.71 respectively for grazing capacity). Species diversity using the Shannon’s index ranged from 1.13 to 2.40. There was spatial heterogeneity in herbage yield, grazing capacity and species diversity in Ghana’s Guinea savannah rangelands with some parts needing effective site-specific improvement strategies for sustainable livestock production.
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    Herder-Farmer Conflicts Amidst Covid-19 Pandemic in West-Africa
    (Ghanaian Journal of Animal Science, 2021) Hagan, B.; Timpong-Jones, E.C.; Osei-Amponsah, R.
    n West Africa, transhumance has been a major system of cattle production in which herders trav el with their herds in search of adequate pasture and water. Unfortunately, the perennial conflicts between the transhumant herders and crop farmers have had negative effects on agricultural pro duction. The objective of this review was to document among others such negative impacts and how COVID-19 has influenced transhumance activities in West Africa. The review was carried out using published articles on the subject from journals, books, online sources and semi-formal inter action from key stakeholders. Climate change, diversification of land use, land tenure systems, perceptions about pastoralists, porous entry points, absence of grazing corridors and failure to ad here to the conditions of the ECOWAS protocol on transhumance were some of the major causes of herder-farmer conflicts. Destruction of crops and animals, loss of human life, rural-urban mi gration, poor living conditions and destruction of homes are some of the major impacts of the herder-farmer conflicts in West Africa. Public education on transhumance, government interven tion and the ability to monitor and adhere to the ECOWAS protocols on transhumance by all countries in the region would help minimize these conflicts. Furthermore, all stakeholders should play their roles and help find innovative and sustainable ways of feeding transhumant cattle in West Africa.
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    Association of Phenotypic Markers of Heat Tolerance with Australian Genomic Estimated Breeding Values and Dairy Cattle Selection Indices
    (Animals, 2023) Osei-Amponsah, R.; Dunshea, F.R.; Leury, B.J.; Abhijith, A.; Chauhan, S.S.
    Dairy cattle predicted by genomic breeding values to be heat tolerant are known to have less milk production decline and lower core body temperature increases in response to elevated temperatures. In a study conducted at the University of Melbourne’s Dookie Robotic Dairy Farm during summer, we identified the 20 most heat-susceptible and heat-tolerant cows in a herd of 150 Holstein Friesian lactating cows based on their phenotypic responses (changes in respiration rate, surface body temperature, panting score, and milk production). Hair samples were collected from the tip of the cows’ tails following standard genotyping protocols. The results indicated variation in feed saved and HT genomic estimated breeding values (GEBVs) (p ≤ 0.05) across age, indicating a potential for their selection. As expected, the thermotolerant group had higher GEBVs for HT and feed saved but lower values for milk production. In general, younger cows had superior GEBVs for the Balanced Performance Index (BPI) and Australian Selection Index (ASI), whilst older cows were superior in fertility, feed saved (FS), and HT. This study demonstrated highly significant (p ≤ 0.001) negative correlations (−0.28 to −0.74) between HT and GEBVs for current Australian dairy cattle selection indices (BPI, ASI, HWI) and significant (p ≤ 0.05) positive correlations between HT and GEBVs for traits like FS (0.45) and fertility (0.25). Genomic selection for HT will help improve cow efficiency and sustainability of dairy production under hot summer conditions. However, a more extensive study involving more lactating cows across multiple farms is recommended to confirm the associations between the phenotypic predictors of HT and GEBVs.