Genomic evaluation of binary traits in dairy cattle by considering genotype × environment interactions

Aim of study: To assess genotype by environment (G×E) interaction via single- and multi-trait animal models for binary traits in dairy cattle.  Area of study: University of Tabriz, Tabriz, Iran. Material and methods: Phenotypic and genomic data were simulated considering a binary trait in four environments as different correlated traits. Heritabilities of 0.05, 0.10, 0.15, and 0.20 were considered to mimic the genetic variation of the binary trait in different environments. Eight scenarios resulted from combining the number of QTLs (60 or 300), LD level (high or low), and incidence of the binary trait (10% or 30%) were simulated to compare the accuracy of predictions. For all scenarios, 1667 markers per chromosome (depicting a 50K SNP chip) were randomly spaced over 30 chromosomes. Multi-trait animal models were applied to take account of G×E interaction and to predict the genomic breeding value in different environments. Prediction accuracies obtained from the single- and multi-trait animal models were compared. Main results: In the models with G×E interaction, the largest accuracy of 0.401 was obtained in high LD scenario with 60 QTLs, and incidence of 30% for the fourth environment. The lowest accuracy of 0.190 was achieved in low LD scenario with 300 QTLs and incidence of 10% for the first environment. Research highlights: Genomic selection with high prediction accuracy can be possible by considering the G×E interaction during the genetic improvement programs in dairy cattle

Prevalence and risk factors of lameness in dairy cattle in Alexandria, Egypt

  Aim of study: Providing further information on the prevalence of lameness in four dairy cattle herds and gain insights into the risk factors associated with the frequency of lameness incidence including farm, frequency of mastitis, and number of lactations.   Area of study: Alexandria, Egypt.   Material and methods: Four dairy Holstein cattle farms near Alexandria Governorate in Egypt were involved in a retrospective investigation of lameness episodes between the years 1987 and 2011. The association between the frequency of lameness injury and the explanatory variables was tested by the maximum likelihood analysis of variance, adopting a loglinear model. The explanatory variables included in the model were farm, frequency of mastitis injury and number of lactations as well as their one-way interactions.   Main results: The prevalence of lameness ranged between zero and 19% in the four farms and the frequency of lameness events (from 0 to 4 times) increased with lactation number and mastitis incidence with correlation coefficients of 0.15 and 0.12, respectively.   Research highlights: Lameness is present in Egyptian dairy cow herds with highly variable prevalence and the risk increases with lactation number and mastitis

Modeling pesticide translocation injected by endotherapy into the stem of coconut tree (Cocos nucifera L.)

Aim of study: To present a mathematical model to simulate the translocation of pesticides injected into coconut trees. Pesticide residues in water and coconut pulp were also evaluated. Area of study: The data were obtained in coconut plants of the Itaporanga Experimental Field, located in the Municipality of Itaporanga d'Ajuda, Sergipe State, Brazil. Material and methods: To estimate the effect of pesticide site-sap coefficients and retardation factors on translocation and its phytosanitary behavior and risk of contamination of coconut fruits, the stipe was modeled by a classic dispersion-advection equation. The pesticides cyproconazole, azoxystrobin, dimethoate, imidacloprid, metalaxyl, and thiamethoxam were injected into the coconut palm stipe. The method used to extract pesticide residues from pulp, water and coconut sap samples was based on the QuEChERS methodology with modifications. Main results: Simulations showed that (i) the pesticides dimethoate, metalaxyl, and thiamethoxan were the active ingredients showing the greatest potential for translocation in the sap of the coconut tree stem; (ii) the pesticides imidacloprid and metalaxyl translocated upward in the stipe, and more rapidly than pesticides abamectin and cyproconazole, which moved slower to the aerial part of coconut plants. In chromatography analysis, no pesticide residues were quantified in water and coconut fruit pulp samples of coconut trees injected with pesticides, after the evaluated intervals. Research highlights: The proposed model allowed us to observe that the translocation is inversely proportional to the sorption of the pesticide in the stem of coconut trees

Identifying optimal monitoring strategies to predict soil hydraulic characteristics and water contents by inverse modeling

Aim of study: To investigate the monitoring strategies that let us to build effective models able to best estimate water contents, θ and pressure heads, h with the least amount of data. Area of study: Field data was acquired in an experimental plot at Bahía Blanca (Argentina). Material and methods: Field data of θ(t), h(t) for six soil depth were used to optimize the SHP (θr, θs, α, n and Ks) by inverse modeling with HYDRUS 1D. Several scenarios of available data from θ(t) and h(t) were considered: (1) six monitoring depths (6-MD); (2) five monitoring depths (5-MD); (3) four monitoring depths (4-MD). Model accuracy was assessed by comparing the measured and predicted θ and h for each monitoring strategy. Additionally, field measured SHP with independent methods were compared to inversely optimized SHP. Main results: The best fit between predicted and observed θ and h was achieved with the 6-MD strategy. Nevertheless, deterioration of statistics EF and rRMSE in the 5-MD or 4-MD schemes were lower than 10%, depending on the location of the missing data. The observation points that had less importance in parameter prediction corresponded to the intermediate vadose zone and to the deeper layers. The proposed strategies presented a better performance than field measured SHP to reproduce soil water retention curves for each layer of the soil profile. Research highlights: By reducing the number of vertical observations in the profile without harming the final SHP estimation, the resources needed in data monitoring strategies can be greatly enhanced

Reproductive physiology and sexual compatibility of the Spanish olive variety ‘Arbequina’ cultivated in Montenegro

Aim of study: One of the newly introduced olive varieties in Montenegro is the Spanish olive (Olea europaea L.) variety ‘Arbequina’. The aim of this work was to study the changes in the reproductive physiology of the cultivar 'Arbequina' in conditions of Montenegro. Area of study: Comparative experimental plots were established in two areas in Montenegro, the coastal region of Ulcinj and the inland region of Podgorica. Material and methods: The research was conducted at four experimental sites (UL1 and UL2 in Ulcinj; PG1 and PG2, in Podgorica) over four years. Flowering phenophases, inflorescence characteristics, and inflorescence architecture were assessed. Pollination trials consisted of open-pollination, self-pollination, and cross-pollination of ‘Arbequina’ with several olive varieties, resulting in an assessment of fruit set. Main results: A high level of fruit set (6.75%) in ‘Arbequina’ in open-pollination was recorded in the multi-varietal orchard (PG2). A much lower fruit set was found in the mono-varietal hedgerow orchards (0.75% in PG1 and 0.33% in UL2). The fruit set was very low in the mono-varietal orchards in self-pollination trials, ranging from 0.01% (PG1) to 0.06% (UL1). Research highlights: These results confirm that ‘Arbequina’ is a self-incompatible variety, which is crucial both for farmers in establishing new plantations and for scientists in future research. Some of the 11 olive varieties cross-pollinated with the ‘Arbequina’ variety displayed pollinating potential, which needs to be proven with paternity tests. Despite the differences between experimental sites and areas, ‘Arbequina’ exhibited high reproductive potential, confirmed by many perfect flowers

Pathogenesis of domestic pigs submitted to mycobacterial sensitizations previous to experimental infection with Mycobacterium bovis

Aim of study: To demonstrate the virulence of a Mycobacterium bovis local pig isolate in order to contribute to a better understanding of the pathological and immunological consequences of M. bovis infection in previous sensitized animals. Area of study: Buenos Aires, Argentina Material and methods: One group of ten pigs received two oral doses of killed M. bovis suspension and a comparative intradermal tuberculin test (CIT) (multiple sensitized) and then was infected with the M. bovis strain. Another group only received the CIT (single sensitized) and the infective dose. Humoral immune response was followed monthly, and gross pathology, histopathological and bacteriological analysis were performed at necropsy 100 days after infection. Main results: M. bovis oral infection induced lesions and allowed bacterial growth in most of the animals. Previous sensitization with killed M. bovis suspension slightly raised the intensity of the response, as the multiple sensitized group showed higher lesion scores and humoral response. Research highlights: Although the differences in lesion scores were not statistically significant, oral route infection after sensitization can modify the course of infections towards a fast development of lesions with a higher fibrotic component suggestive of increased resistance to infection in the right conditions

A new approach to assessing competition from trees on Nelder wheels

Aim of the study: To develop an index to describe the competition of trees of Eucalyptus spp. clones in different densities; also, to evaluate the productivity of the clones on Nelder wheels (NWs). Area of study: Ten Eucalyptus spp. clones distributed in nine NWs, located in the northern state of Tocantins, Brazil. Material and methods: A new competition index was formulated as the ratio of geometric areas and average cross-sectional areas of sampling units from different locations on the NW referenced to a unit taken in the center of it. Besides, two distance-dependent indices were tested to evaluate their performance in different spacings. The correlation between the competition indices and the variables height, diameter, volume and cross-sectional area, average distance and mortality percentage was evaluated. To check the difference in productivity between the clones we used MANOVA and discriminant analysis. Main results: The Alba-Péllico index provides a better understanding of the competitive relationship between trees, as well as a better explanation of the competitive process in the NWs than the other indices evaluated. The variation in the basal area between the clones in the less dense locations, substantiates the characteristics of each clone or possible interferences of the location since in this condition they are free from the influence of spacing and competition. This shows that competition is more influential than other characteristics of sites and genotypes in the behavior in diameter, basal area and volume in the densest sites. Research highlights: The characteristics of the Alba-Péllico index indicate good interpretation to understand the competitive relationship among trees since the results vary between 0 and 1, and the closer to zero the smaller or non-existence of competition

Replacement of inorganic trace minerals by chelated minerals in pullet diets (12 to 20 weeks of age)

Aim of study: An experiment was carried out aimed to evaluate the effects of different levels and sources of trace mineral to laying pullets with two initial body weights (BWs). Area of study: The experiment was carried out in Federal University of Goiás, Goiânia, Goiás, Brazil Material and methods: Two hundred and eighty eight Bovans White pullets aged 12 weeks old were allotted in a completely randomized design and a 2×3 factorial arrangement, wherein the main effects included initial BW (light-weight and heavy-weight) and three dietary trace mineral sources and levels (100% inorganic, 100% chelated and low-dose corresponding to 50% chelated), totalizing six treatments with eight replicates of six birds. The performance, the metabolizability coefficient of nutrients, and the onset of lay were evaluated at rearing phase (12 to 20 weeks). At 17th and 20th weeks of age, the relative weight of reproductive and digestive organs, abdominal fat, and tibia quality were assessed. A residual effect was evaluated at production phase on productive performance and egg quality. Main results: The mineral source did not affect the performance of pullets. Birds fed 50% chelated mineral produced the lowest eggshell. The heavy-weight birds showed higher egg weight and eggshell quality. The lighter birds showed lower abdominal fat weight and lower tibia robustness index. Research highlights: The replacement of 100% of inorganic mineral for chelated mineral do not result in decrease of bird performance at rearing and at production phase, but a minimum amount should be provided to ensure growth and nutrient metabolizability