Correction: Genetic diversity and population structure of indigenous chicken in Rwanda using microsatellite markers.

[This corrects the article DOI: 10.1371/journal.pone.0225084.].

Effect of feed supplementation of Dacryodes edulis parts' powder as prebiotic on the growth traits, ceca microbiota and blood parameters of local chickens.

This study aimed at testing the efficacy and safety of Dacryodes edulis plant parts in diets fed to chicken. The plant has potential for use as a natural prebiotic to substitute the conventionally used antibiotic growth promoters in poultry production. Phytochemical analyses of the plant leaves, stem, and bark combination (stembark) and seed powders from the D. edulis were carried out. The powder from the three D. edulis plant parts were used as supplement in formulating six experimental diets tested in this study. The diets were TL0Ed (0.5% leaves powder), TL1Ed (1.0% leaves powder), TB0Ed (0.5% stembark powder), TB1Ed (1.0% stembark powder), TS0Ed (0.5% seeds powder), and TS1Ed (1.0% seeds powder). Besides, a positive (T+ positive control; 0.5-g oxytetracycline as recommended by the manufacturer) and a negative (T- negative control; having no commercial antibiotic and no plant supplement) diets were prepared for comparison purposes. The diets were fed to a total of 288 dual-purpose chicken for a period of 14 weeks. The chicken growth and body composition characteristics, blood chemistry, and microbiota count were collected and used as indicators of the plant parts efficacy and safety. The analysis of the D. edulis plant parts significantly differed (P ≤ 0.05) in their phytochemical contents. The initial body weight and feed conversion efficiency ratios were not significantly different (P ≥ 0.05) between and among treatment groups. However, significant differences (P ≤ 0.05) were detected in the feed intake and body weight gain at eighth week. Live weight at eighth week was significantly different (P ≤ 0.05) with its values ranging between 503.32 and 614.93 g for treatments TL1Ed and TNeg-, respectively. The dietary treatment of D. edulis leaves, stembark, and seed powder at the two inclusion levels significantly (P ≤ 0.05) decreased the colonies forming unit of Escherichia coli and Salmonella sp. as compared with negative control treatment in the eighth week phase. The level of glucose, total cholesterol, triglycerides, aspartate aminotransferase, alanine amino transferase, alkaline phosphatase, and the packed cell volume did not differ significantly (P ≥ 0.05) between and among dietary D. edulis treatments. The findings from this research provide crucial information on the efficacy and safety of D. edulis plant parts. This is an important step in testing the potential of the plant in use as a prebiotic in chicken feeds production.

Genetic diversity and population structure of indigenous chicken in Rwanda using microsatellite markers.

Rwanda has about 4.5 million of indigenous chicken (IC) that are very low in productivity. To initiate any genetic improvement programme, IC needs to be accurately characterized. The key purpose of this study was to ascertain the genetic diversity of IC in Rwanda using microsatellite markers. Blood samples of IC sampled from 5 agro-ecological zones were collected from which DNA was extracted, amplified by PCR and genotyped using 28 microsatellite markers. A total of 325 (313 indigenous and 12 exotic) chickens were genotyped and revealed a total number of 305 alleles varying between 2 and 22 with a mean of 10.89 per locus. One hundred eighty-six (186) distinct alleles and 60 private alleles were also observed. The frequency of private alleles was highest in samples from the Eastern region, whereas those from the North West had the lowest. The influx of genes was lower in the Eastern agro-ecological zone than the North West. The mean observed heterozygosity was 0.6155, whereas the average expected heterozygosity was 0.688. The overall inbreeding coefficient among the population was 0.040. Divergence from the Hardy-Weinberg equilibrium was significant (p<0.05) in 90% of loci in all the populations. The analysis of molecular variance revealed that about 92% of the total variation originated from variation within populations. Additionally, the study demonstrated that IC in Rwanda could be clustered into four gene groups. In conclusion, there was considerable genetic diversity in IC in Rwanda, which represents a crucial genetic resource that can be conserved or optimized through genetic improvement.

Polymorphisms of the Chicken Mx Gene Promoter and Association with Chicken Embryos' Susceptibility to Virulent Newcastle Disease Virus Challenge.

Newcastle disease is a devastating viral disease of chicken in low- and middle-income countries where the backyard production system is predominant. Marker-assisted selection of chickens that are resistant to Newcastle disease virus (NDV) is the promising strategy that needs to be explored. The aim of the present study was to investigate polymorphisms of the promoter region of the chicken Mx gene and association with Kuroiler, Sasso, and local Tanzanian chicken embryos' survival variability to virulent NDV infection. Chicken embryos were initially challenged with a minimum lethal dose of virulent NDV suspension and then were followed over time to gather information on their survival variability. Using the survival data, high and less susceptible cohorts were established, and a total of 88 DNA samples from high and less susceptible groups were genotypes by sequencing. Five single-nucleotide polymorphisms (SNPs), which were previously reported, were detected. Interestingly, for the first time, the findings demonstrated the association of the promoter region of chicken myxovirus-resistance (Mx) gene polymorphisms with chicken embryos' susceptibility to the virulent NDV challenge. At the genotypic level, the SNP4 G > A mutation that was located within the IFN-stimulating response element was associated (LR: 6.97, P=0.03) with chicken embryos' susceptibility to the virulent NDV challenge. An allele G frequency was higher in the less susceptible cohort, whereas an allele A frequency was higher in the high susceptible cohort. At the haplotype level, the haplotype group ACGC was associated (OR: 9.8, 95% CI: 1.06-79.43, P=0.042) with the same trait and had a resistant effect. In conclusion, the results have demonstrated the association of chicken Mx gene promoter polymorphisms and chicken embryos' survival variability to the virulent NDV challenge, and the information is useful for breeding programs designed to develop chicken genotypes that are resistant to Newcastle disease virus.

A comprehensive survey of the prevalence and spatial distribution of ticks infesting cattle in different agro-ecological zones of Cameroon.

BACKGROUND: Ticks and tick-borne diseases are a major impediment to livestock production worldwide. Cattle trade and transnational transhumance create risks for the spread of ticks and tick-borne diseases and threaten cattle production in the absence of an effective tick control program. Few studies have been undertaken on cattle ticks in the Central African region; therefore, the need to assess the occurrence and the spatial distribution of tick vectors with the aim of establishing a baseline for monitoring future spread of tick borne-diseases in the region is urgent. RESULTS: A total of 7091 ixodid ticks were collected during a countrywide cross-sectional field survey and identified using morphological criteria. Of these, 4210 (59.4%) ticks were Amblyomma variegatum, 1112 (15.6%) Rhipicephalus (Boophilus) microplus, 708 (10.0%) Rhipicephalus (Boophilus) decoloratus, 28 (0.4%) Rhipicephalus (Boophilus) annulatus, 210 (3.0%) Hyalomma rufipes, 768 (10.8%) Hyalomma truncatum, and 19 (0.3%) Rhipicephalus sanguineus. Three ticks of the genus Hyalomma spp. and 33 of the genus Rhipicephalus spp. were not identified to the species level. Cytochrome c oxidase subunit 1 (cox1) gene sequencing supported the data from morphological examination and led to identification of three additional species, namely Hyalomma dromedarii, Rhipicephalus sulcatus and Rhipicephalus pusillus. The finding of the invasive tick species R. microplus in such large numbers and the apparent displacement of the indigenous R. decoloratus is highly significant since R. microplus is a highly efficient vector of Babesia bovis. CONCLUSIONS: This study reports the occurrence and current geographical distribution of important tick vectors associated with cattle in Cameroon. It appears that R. microplus is now well established and may be displacing native Rhipicephalus (Boophilus) species, such as R. decoloratus. This calls for an urgent response to safeguard the livestock sector in western central Africa.