Research articles

Canopy height from drone photogrammetry better predicts aboveground biomass than vegetation greenness indices in a semi-arid savanna

2026-11-03T09:37:38Z

Canopy height from drone photogrammetry better predicts aboveground biomass than vegetation greenness indices in a semi-arid savanna Nare, Alan D; Slade, Glenn; Akanyang, Lawrence; Perkins, Jeremy S; Cunliffe, Andrew M Semi-arid rangelands support livelihoods and key ecosystem services, yet sustainable management depends on accurate and scalable monitoring of herbaceous aboveground biomass (AGB). Field-based measurements are spatially limited, while satellite-derived vegetation indices often perform poorly in complex savanna systems such as the Kalahari. Using unoccupied aerial vehicle (UAV) structure-from-motion (SfM) photogrammetry, we evaluate the ability of fine-scale canopy height and spectral reflectance metrics to predict herbaceous biomass across a grazing intensity gradient. Canopy height consistently predicted AGB across all grazing levels, whereas normalised difference vegetation index (NDVI) effects were weak and grazing-dependent. The UAV-derived canopy height showed strong relationships with total herbaceous AGB, explaining up to 72% of observed variation, whereas vegetation greenness measured using NDVI showed limited predictive power. In contrast, predicting biomass of foraging importance proved challenging, with UAV-derived structural and spectral metrics explaining only a small proportion of variation. Together, these findings highlight the value of UAV-derived structural measurements over traditional spectral indices for fine-scale rangeland monitoring in semi-arid systems, while underscoring the limitations of current UAV-based spectral and structural metrics for assessing forage value across species and sites. Journal Article

Genome-wide analysis of inbreeding patterns and candidate genes for adaptation in indigenous chickens of Botswana

2026-10-14T01:00:25Z

Genome-wide analysis of inbreeding patterns and candidate genes for adaptation in indigenous chickens of Botswana Chalebgwa, A.B.; Machete, J.B.; Monau, P.I.; Kgwatalala, P.M.; Moreki, J.; Nsoso, S.J. Indigenous chickens are an important genetic resource in Botswana, providing protein, cultural value and economic benefits to rural communities. The Tswana chicken, comprising multiple strains including Dwarf, Nakedneck, and Normal, has been shaped by domestication, local adaptation and traditional management practices. However, the lack of structured breeding strategies raises concerns about genetic erosion. This study evaluated genomic inbreeding patterns and signatures of selection in Tswana chicken strains using genome-wide SNP data from the 60 K iSelect chicken array. After quality control in PLINK v1.9, 52,719 SNPs from 81 chickens were retained for analysis. Runs of homozygosity (ROH) analysis and complementary selection signature approaches (FST, iHS, Rsb, and xp-EHH) were applied and results revealed generally low levels of inbreeding FROH (Dwarf: 0.01396; Nakedneck: 0.00921; Normal: 0.01216), with most ROH segments being short (<8 Mb).This may indicate that homozygosity largely reflects historical demographic processes rather than recent widespread inbreeding. Long ROH segments were observed only in a subset of Normal individuals, suggesting localized recent relatedness rather than strain-wide effects. A prominent ROH hotspot consistently detected on GGA5 (1.92–3.75 Mb) was shared across all strains and harbored candidate genes including NELL1, ANO5 and SLC17A6 which are implicated in skeletal integrity, neuromuscular function and metabolic processes. In addition, four (4) candidate genes on GGA8 and GGA15 (BRINP3, C1orf21, ISCU, RNF2) were also identified by multiple analytical methods. Collectively, the results indicate low current inbreeding, measurable but moderate population structure and candidate genomic regions potentially associated with adaptation to local production environments. These findings provide a genomic foundation for the sustainable management of Tswana chicken genetic resources. Journal Article

Effects of season, parity and stage of lactation on yield, composition and microbial quality of milk from camels raised in Tsabong, Botswana

2026-10-08T01:00:25Z

Effects of season, parity and stage of lactation on yield, composition and microbial quality of milk from camels raised in Tsabong, Botswana Seifu, Eyassu; Madibela, Othusitse Ricky; Boitumelo, Wame Shimane; Angassa, Ayana; Mpho, Kennedy; Molapisi, Moenyane; Kobue-Lekalake, Rosemary; Haki, Gulelat Desse; Bultosa, Geremew; Teketay, Demel Background: Introduced to Botswana in the early 20th century, dromedaries remain little exploited for milk production. In Tsabong, the herd is mainly used for tourism, and no study has yet assessed influencing factors on milk yield or composition. Aim: This study was conducted to assess the effects of season, parity, and stage of lactation on the yield, composition, and quality of camel milk at the Tsabong Ecotourism Camel Park. Methods: Twenty lactating camels, averaging eight years old and at various lactation stages (early, mid, and late) and parities (2–6), were studied. They browsed freely during the day and received 3 kg of a 1:1 saltbush–sorghum bran supplement at night, with unlimited access to water and salt. Milk yield was measured every three days over six weeks. A total of 560 records were collected during the dry season and 640 during the wet season. Milk samples for chemical and microbiological analysis were collected six times over a two-week period. Data were analysed using SAS for non-balanced data. Results: Milk yields were significantly higher during the wet season (1,340 ml/day) than during the dry season (781 ml/day). In the dry season, milk yield decreased as parity increased, while in the wet season, milk yield increased up to the fifth parity before declining. The stage of lactation significantly influenced fat, protein, solids-not-fat (SNF), and density in the dry season. Early lactation milk had higher protein, SNF, and density, while fat content peaked in mid lactation. In the wet season, only the protein content varied significantly across lactation stages. Parity significantly affected titratable acidity, protein, and lactose in the dry season, and protein, lactose, total solids, SNF, and pH in the wet season. The highest values were observed in camels at their second parity during the wet season. Fat and total solids were higher in the wet season overall. Coliform counts were generally higher in samples collected during the wet season. Salmonella was detected in 3.42% of dry season samples and 1.7% of wet season samples, highlighting public health concerns. Conclusions: These findings highlight the need for improve Journal Article

Assessment of the Welfare of Working Horses: Combining Clinical Evaluations with Indirect Indicators

2026-10-08T01:00:22Z

Assessment of the Welfare of Working Horses: Combining Clinical Evaluations with Indirect Indicators Basher, Abdallah A.; Ahmed, Abdelkareem A.; Pfukenyi, Davies M.; Essa, Mohamed Osman Abdalrahem; Husien, Hosameldeen Mohamed; Saleh, Ahmed A.; Adam, Saber Y.; Cai, Demin Assessing the welfare of the working horses is crucial for identifying health and management issues and implementing effective solutions. This study evaluated the welfare of working horses in South Darfur, Sudan, by integrating clinical examination with indirect indicators through owner interviews. A total of 400 horse–owner pairs were included. Most horses (61.7%) worked every day, and 77% of owners reported using whips to encourage movement. Clinical assessment revealed that 29.0% of horses were thin, over half had dirty coats, 50.5% harbored external parasites, 43% had abnormal discharges, 25.0% showed poor hoof health, and many exhibited gait abnormalities. Behavioral assessments indicated that fewer than 40% of horses displayed alert attitudes, while over half responded indifferently to stimuli. Horses working daily tended to be thin, have skin lesions, and show gait problems, reflecting poor welfare. Horses with better attitude responses were more frequently fed and worked fewer days per week. Overall, the findings highlight poor physical, behavioral, and management conditions among working horses, emphasizing the urgent need for owner education, training programs, and further research to improve their welfare in the study area. Journal Article