Antibacterial activity of medicinal plants on the management of mastitis in dairy cows: A systematic review

BACKGROUND

Mastitis is a disease of economic importance in dairy production systems. The common management regime for mastitis is the use of synthetic antibiotics, giving a new problem of antibiotic resistance. There is, therefore, a need to prospect for alternatives to conventional antibiotics from herbal plants.

OBJECTIVES

This systematic review evaluates the use of plants as alternatives for the control of mastitis in dairy cattle, focussing on the effectiveness of studied plants and plant-based products and possible implications on the use of these products in livestock health.

METHODOLOGY

The PRISMA model was implemented with searches done in five electronic databases: Scopus, ScienceDirect, PubMed, Ovid and Research4Life. Data were extracted from 45 studies with 112 plant species from plant species belonging to 42 different families. The specific keywords were 'mastitis', 'dairy cows' and 'medicinal plants'.

RESULTS

The most cited plant species included Allium sativum L., Azadirachta indica and Eucalyptus globulus Labill with the latter further exploring its components. Microbial species causing mastitis mainly were Staphylococcus aureus and Escherichia coli. The extraction methods used included maceration approach using ethanol, methanol and water as solvents for phytochemicals and chromatographic techniques for essential oils. A few studies explored the mode of action, and toxicities of the herbal extracts as well as evaluating their efficacy in clinical trials using animal models.

CONCLUSION

Plants with defined levels of phytochemicals were essential sources of antibacterials. Standardisation of analytical methods is required.

Short-term impacts of soil nutrient management on maize (Zea mays L.) productivity and weed dynamics along a toposequence in Eastern Zimbabwe

Poor soil fertility and weed infestation are among major constraints to maize production in southern Africa. Nutrient and weed management strategies that are products of empirical research, are needed to improve efficiencies on farms. A field experiment was carried out in Eastern Zimbabwe on three smallholder farms positioned on upper, middle and lower catena. The farms differed in soil organic carbon (SOC) content, 3.9, 6.4 and 8.9 g kg⁻¹ (hereafter referred to as low, medium and high), respectively, and are located within one km distance. The objective of the study was to investigate short-term (6 years) repeated application of soil nutrient amendments on maize productivity and weed dynamics across a soil fertility gradient. Treatments included strategic combinations of NPK fertiliser, cattle manure, and lime. On each farm, a randomised complete block design with three replicates was used. Multivariate, Principal Component Analysis, was used to establish the relationship between season, SOC content, nutrient management, and weed density. Maize yield was strongly linked to SOC content, with six-year mean maize grain yields of 1.31, 2.47, and 2.75 Mg ha⁻¹ for low, medium, and high SOC content, respectively. Maize grain yields with cattle manure (CM) or NPK application were only 0.25 and 0.60 Mg ha⁻¹, respectively for the poorest SOC content field. However, when manure was combined with NPK fertiliser, yields at the site substantially increased to 1.5 Mg ha⁻¹ while in medium and high SOC recorded 2.47 and 2.75 Mg ha⁻¹ respectively. Weed density, and biomass were larger in the medium, and high SOC content. Richardia scabra, Melinis repens, and Cyperus sp. were associated with low SOC. Luecus martinicensis, Bidens pilosa, and Galinsoga parviflora were linked to medium and high SOC content. Results from this study suggest site-specific weed management approach. On soils critically poor in SOC content, maize yield gains are only achieved when organic and mineral fertilisers are combined. Our results also suggest that farmers must increase vigilance and intensity of weed management in soils with medium and high SOC content, particularly after application of CM.

Evaluation of a pre-formulated post-emergence herbicide mixture of topramezone and dicamba on annual weeds and Bermuda grass in maize in a sub-tropical agro-ecology

Weed infestation is one of the major causes of low maize grain yield in sub-Saharan Africa (SSA). The perennial grass weed, Cynodon dactylon (L.) Pers., is one of the most problematic weeds in maize in SSA. A pre-formulated post-emergence herbicide mixture (50 g a.i. topramezone litre⁻¹ + 160 g a.i. dicamba litre⁻¹), sold under the trade name Stellar-Star^®, was evaluated for C. dactylon and general weed control in the 2013/14 and 2014/15 season. The experiment was laid out as a randomized complete block design (RCBD) with six treatments replicated thrice, namely; weedy control, hoe weeding at 3 and 6 weeks after crop emergence (WACE), a label recommended dose of Stellar-Star at 3 WACE, a reduced Stellar-Star dose (75% of label dose) at 3 WACE, a double dose of Stellar-Star split applied at 3 and 6 WACE and a tank mix of label doses of Stellar-Star + Atrazine applied at 3 WACE. The Stellar-Star herbicide treatments did not significantly (P > 0.05) affect C. dactylon density at 5 WACE but significantly reduced (P < 0.001) its density at 10 WACE. The Stellar-Star herbicide treatments significantly reduced (P < 0.001) weed biomass compared to the weedy-check at 5 and 10 WACE in both seasons. The Stellar-Star double dose split application and the Stellar-Star Atrazine tank mix were most effective in controlling C.dactylon (90–97% control) followed by the Stellar-Star label dose and Stellar-Star reduced dose (75%–88% control), however, the results of this study suggest that the Stellar-Star Atrazine tank mix provided the most effective early season and overall weed control and resulted in the highest yield, rainfall use efficiency (RUE) and gross margin and is recommended.

Short-term Impacts of Tillage and Fertilizer Treatments on Soil and Root Borne Nematodes and Maize Yield in a Fine Textured Cambisol

Conservation agriculture (CA) based on the principles of minimum soil disturbance, crop residue retention, and crop rotation has been the focus of intensive research in recent years. A study was carried out to determine the effects of tillage and fertilizer on the population densities of plant-parasitic nematodes in maize. Three tillage regimes, (i) basin planting, (ii) rip line seeding, and (iii) conventional tillage, were combined with four fertilizer regimes: (i) no-fertilizer, (ii) low fertilizer rate, (iii) medium fertilizer rate, and (iv) high fertilizer rate. The experiment was arranged as a split plot in randomized complete block design, replicated three times with tillage as the main plot factor and fertilizer as the sub-plot factor. The study was conducted on fine-textured Cambisol soils at Chinhoyi University of Technology farm, Zimbabwe, over two cropping seasons between December 2014 and April 2016. Eight plant-parasitic nematode genera were observed belonging to five groups based on their feeding sites: (i) sedentary endoparasites ( Meloidogyne and Rotylenchulus ), (ii) migratory endoparasites ( Pratylenchus ), (iii) semi-endoparasites ( Scutelonema and Helicotylenchus ), (iv) ectoparasites ( Xiphinema and Trichodorus ), and (v) algal, lichen or moss feeders ( Tylenchus ). In both cropping seasons, semi-endoparasitic nematodes were double under rip line seeding and triple under basin planting compared to conventional tillage. Basin planting had higher plant-parasitic nematode richness than rip line seeding. Nematode densities did not have a measurable effect on maize grain yield. Maize grain yield was higher in rip line seeding (37%) and planting basins (52%) than conventional tillage during 2014/15 cropping season. On the other hand, during 2015/16 cropping season, maize grain yield was 78% and 113% higher in rip line seeding and basin planting, respectively, compared to conventional tillage. The results show that under the environmental and edaphic conditions of this specific study site, semi-endoparasitic nematodes were higher under rip line seeding and basin planting compared to conventional tillage. The authors conclude that (i) plant-parasitic nematode genera exhibited differential responses to different tillage systems but were not affected by fertilizer application, and (ii) in the present study, maize grain yield response under different tillage and fertilizer regimes was overall not related to nematode population density and composition.

Effect of substrate quantity and shelf position on yield of oyster mushroom (Pleurotus sajor caju)

An experiment was conducted in Harare (Zimbabwe) in 2004 to investigate the effect of substrate (wheat straw) quantity and shelf position on yield of oyster mushroom (Pleurotus sajor-caju) using plastic tray culture. The experiment was laid out as a 2-way factorial in a randomized block design with five substrate quantities (2, 4, 6, 8 and 10 kg of wheat straw per tray) and two shelf positions (0.5 and 1.2 m above ground). Mushroom yield increased with an increased substrate quantity of up to 6 kg and thereafter remained constant. Shelf position had no significant effect (p > 0.05) on mushroom yield and there was no interaction (p > 0.05) between substrate quantity and shelf position on yield. Biological efficiency decreased with an increase in substrate quantity per tray. It was concluded that 6 kg of substrate per tray (50x35 and 20 cm deep) would result in optimal yields. The height above the ground at which trays are placed in the growing room does not affect mushroom yields.