School of Agriculture Science and Technology

Is neutral genetic diversity related to quantitative variation in semen traits in bulls?

Sat, 01 May 2021 00:00:00 GMT

Is neutral genetic diversity related to quantitative variation in semen traits in bulls? Gororo, Eddington; Chatiza, Fungayi Primrose; Chidzwondo, Farisai; Marshall Makuza, Stanley Conservation decisions based on neutral genetic diversity have been observed to promote retention of useful quantitative variation in biological populations. An experiment was undertaken to determine the association between microsatellite marker polymorphisms and phenotypic variation in semen production and cryosurvival traits in bulls. Thirty-five ejaculates were collected from ten bulls of two breeds and evaluated before and after cryopreservation for several semen traits. The bulls were also genotyped using a set of sixteen bovine-specific microsatellite marker loci. Fixation indices (FST), heterozygosity and Nei's genetic distance measures were computed from allele frequency data for each of the bulls. Molecular and phenotypic data were used to compute tri-distance matrices for the ten bulls and correlated using Mantel's test in GenAIEx 6.5. The study revealed extensive heterogeneity in semen traits, heterozygosity and FST values among the bulls. Large pairwise phenotypic and genetic distances were also observed. Correlation between pairwise genetic distances and phenotypic distances was significant and highly positive for sperm viability (r = .61, p < .001) and moderately positive for sperm motility (r = .40–42, p < .05) variables. For sperm morphology, ejaculate volume and sperm concentration, correlation with genetic distances was positive, low and not significantly different from zero (p > .05). A tendency for a triangular-shaped relationship between genetic and phenotypic distances for post-thaw motility and viability traits was also observed. Accordingly, association with neutral genetic diversity was absent for semen production traits and moderate to highly positive for sperm cryosurvival traits. Given these findings, conservation decisions based on neutral genetic diversity may capture variation in some adaptive traits, but not others.

Organic soil fertility amendments enhance surface-dwelling beetle diversity in a sub-humid tropical environment under conservation agriculture

Mon, 01 Feb 2021 00:00:00 GMT

Organic soil fertility amendments enhance surface-dwelling beetle diversity in a sub-humid tropical environment under conservation agriculture Mashavakure, Nilton; Chomufanaa, Nyaradzo M.; Musiyiwa, Kumbirai; Nyamangara, Justice Surface-dwelling beetles offer ecosystem services in agro-ecosystems including biological pest control and organic matter decomposition. This study was conducted to investigate beetle community response to six years of tillage, crop residue application, crop rotation and soil fertility amendments (low fertiliser, high fertiliser, manure, manure + low fertiliser and manure + 60 kg N ha−1) treatments. Reduced tillage increased beetle abundance by 4.6% relative to soil inversion tillage. Crop residue application increased the abundances of Platynus assimilis, Zophosis boei and total beetles by two to three times. Meanwhile, Renatiella reticulata increased by 628.6% in high fertiliser compared to manure + 60 kg N ha−1, manure + low fertiliser and the control. In crop rotation + crop residue retention plots, application of sole manure at 10 t ha−1 increased the Shannon index by 360–365% relative to manure + 60 kg N ha−1 and manure + low fertiliser. Based on the findings in this study, it can be concluded that reduced tillage, retention of crop residues on the soil surface and application of manure increase surface-dwelling beetle abundance and diversity.

Stewardship of Wild and Farmed Edible Insects as Food and Feed in Sub-Saharan Africa: A Perspective

Sun, 21 Feb 2021 00:00:00 GMT

Stewardship of Wild and Farmed Edible Insects as Food and Feed in Sub-Saharan Africa: A Perspective Musundire, Robert; Ngonyama, Dianah; Chemura, Abel; Ngadze, Ruth Tambudzai; Jackson, Jose; Jekanyika Matanda, Margaret; Tarakini, Tawanda; Langton, Maud; Chiwona-Karltun, Linley Edible insects have gained popularity as alternative food resources in the face of climate change and increasing carbon and environmental footprints associated with conventional agricultural production. Among the positive attributes thatmake edible insects suitable as food and feed substrates include rapid reproduction, high energy conversion efficiency, wide distribution, diversity, reduced greenhouses gases and ammonia emissions, possibility to reduce waste and high nutritional composition. In Sub-Saharan Africa, considerable scientific data exist on use of insects as food and livestock feed. However, coherent policies regarding safety, sustainability, trade and regulation of insects as food and animal feed are lacking. The benefits associated with edible insects are likely to accrue in Sub-Saharan Africa through use of a combination of approaches such as ensured sustainable utilization of edible insects in the wild, preservation of traditional conservation, harvesting and consumption practices, development of captive mass production schemes and strengthening robust value chains to incentivise indigenous participants. Collectively these approaches are referred to as the steward and use of insects as food and animal feed. This paper examines the policy frameworks that exist to support the use of edible insects as food and feed on the African continent. This investigation employed a literature review focussing on national policies in selected African countries to assess the relevance to edible insects. Using a baseline of more than 10 edible insect species consumed, 10 country cases in Sub-Saharan Africa were used to support our in-depth examination of the policy situation that may support good stewardship of edible insects as food and feed. Focus on how policies encompassing biodiversity, natural resources, culture, education, research, technology development, trade, health and nutrition and how that could be improved to support inclusivity of edible insects is discussed. We conclude by proposing a pathway that may accelerate recognition and valorisation of edible insects as important food and feed resources in Sub-Saharan Africa including improving policies to support good stewardship of these resources for sustainability.

Binding E􀂨cacy of Clay Binders in Optimized Ash- Based Vitamin-Mineral Block Licks for Cattle

Fri, 01 Jan 2021 00:00:00 GMT

Binding E􀂨cacy of Clay Binders in Optimized Ash- Based Vitamin-Mineral Block Licks for Cattle Mutore, Rachel; Mpofu, Irvin D.T; Bangira, Courage; Madzimure, James An experiment was done to fabricate summer and winter optimized ash-based vitamin-mineral block lick specimens using cement, bentonite, kaolinite and a combination of these as binders in a ratio of 1:1(w/w) at 15% and 20% inclusion levels, respectively. Treatments were: cement, bentonite, kaolinite, bentonite + cement, bentonite + kaolinite and cement + kaolinite. Bentonite, kaolinite and ash (prime ingredient) were analyzed for mineral pro􀂦le prior to fabrication. Resulting block specimens were analyzed for compressive strength and water absorption as a measure of the binding e􀂨cacy. There was no signi􀂦cant difference (P>0.001) in compressive strength (525± 11.43kPa) for cement and bentonite + cement summer blocks. Compressive strength was signi􀂦cantly higher (P<0.001) in winter block specimens made from the combination of cement and bentonite (47.33± 1.37 kPa). Clays as sole binder could not agglutinate winter blocks. Summer block specimens comprising of cement had the signi􀂦cantly least (P<0.001) water absorption value (1.40 ± 0.923%). Therefore, cement can be combined with bentonitic clay at a ratio of 1:1 summer block licks (500kPa) and winter block licks (39 ± 1 .37kPa) of desirable strength that animals can lick slowly.