Genetic Selection Of Animals Research Articles

Differences in caecal microbiota composition and Salmonella carriage between experimentally infected inbred lines of chickens

BackgroundSalmonella Enteritidis (SE) is one of the major causes of human foodborne intoxication resulting from consumption of contaminated poultry products. Genetic selection of animals that are more resistant to Salmonella carriage and modulation of the gut microbiota are two promising ways to decrease individual Salmonella carriage. The aims of this study were to identify the main genetic and microbial factors that control the level of Salmonella carriage in chickens (Gallus gallus) under controlled experimental conditions. Two-hundred and forty animals from the White Leghorn inbred lines N and 61 were infected by SE at 7 days of age. After infection, animals were kept in isolators to reduce recontamination of birds by Salmonella. Caecal contents were sampled at 12 days post-infection and used for DNA extraction. Microbiota DNA was used to measure individual counts of SE by digital PCR and to determine the bacterial taxonomic composition, using a 16S rRNA gene high-throughput sequencing approach.ResultsOur results confirmed that the N line is more resistant to Salmonella carriage than the 61 line, and that intra-line variability is higher for the 61 line. Furthermore, the 16S analysis showed strong significant differences in microbiota taxonomic composition between the two lines. Among the 617 operational taxonomic units (OTU) observed, more than 390 were differentially abundant between the two lines. Furthermore, within the 61 line, we found a difference in the microbiota taxonomic composition between the high and low Salmonella carriers, with 39 differentially abundant OTU. Using metagenome functional prediction based on 16S data, several metabolic pathways that are potentially associated to microbiota taxonomic differences (e.g. short chain fatty acids pathways) were identified between high and low carriers.ConclusionsOverall, our findings demonstrate that the caecal microbiota composition differs between genetic lines of chickens. This could be one of the reasons why the investigated lines differed in Salmonella carriage levels under experimental infection conditions.

Cluster analysis to explore additive-genetic patterns for the identification of sheep resistant, resilient and susceptible to gastrointestinal nematodes

Infection caused by gastrointestinal nematodes is an important issue for animal health and production. Controlling worm infections improves the sustainability of the sheep industry. Genetic selection of animals that are resistant to gastrointestinal nematodes is another strategy to render sheep production more sustainable by decreasing the use of anthelmintics. The aims of this study were (1) to explore the additive-genetic pattern of EBVs for Famacha© (FAM), packed-cell volume (PVC), and fecal egg counts (FEC) of Santa Ines sheep, (2) to propose a classification of animals that are resistant, resilient and susceptible to gastrointestinal nematodes based on their additive-genetic patterns, and (3) to identify the most suitable animals for selection based on their genetic pattern. A dataset of 2,241 records from 747 animals was used to predict the breeding values for indicator traits of resistance to gastrointestinal nematodes with THRGIBBS1F90 and to carry out cluster analyses was used R software. Three clusters of animals were found in the population using hierarchical cluster analysis of the breeding values for FAM, PCV and FEC. Each cluster was characterized by different additive-genetic patterns identified by k-means non-hierarchical cluster analysis. Among a total of 747 animals, 196 were classified as resistant, 288 as resilient, and 263 as susceptible. Cluster analysis is a valuable tool for data screening that permits to evaluate only selection candidates based on their additive-genetic pattern for gastrointestinal nematode resistance. EBVs for FEC were decisive to divide the population into resilient, resistant and susceptible animals. It is also important to include the EBVs for PCV and FAM to adequately distinguish resistant from resilient animals. Finally, the resistant cluster consisted of the most desirable animals to be used as selection candidates in order to genetically improve resistance to infection with gastrointestinal nematodes. This cluster contained animals with the most appropriate additive-genetic pattern to achieve the breeding goal, with positive breeding values for PCV and negative breeding values for FAM and FEC.

High Heritabilities for Antibiotic Usage Show Potential to Breed for Disease Resistance in Finishing Pigs.

The use of antimicrobials in animal production is under public debate, mainly due to the risk of transfer of resistance to pathogenic bacteria in humans. Therefore, measures have been taken during the last few decades to reduce antibiotic usage in animals, for instance, by national monitoring programmes and by improving animal health management. Although some initiatives exist in molecular genetic selection, quantitative genetic selection of animals towards decreased antibiotic usage is an underexplored area to reduce antibiotic usage. However, this strategy could yield cumulative effects. In this study, we derived new phenotypes from on-farm parenteral antibiotic records from commercially grown crossbred finishing pigs used in the progeny test of Piétrain terminal sires to investigate the heritability of antibiotics usage. Parenteral antibiotic records, production parameters and pedigree records of 2238 full-sib pens from two experimental farms in Belgium between 2014 and 2020 were analysed. Heritability estimates were moderate (18–44%) for phenotypes derived from all antibiotic treatments, and low (1–15%) for phenotypes derived from treatments against respiratory diseases only. Moreover, genetic correlations between these new phenotypes and mortality were low to moderate (0.08–0.60) and no strong adverse genetic correlations with production traits were found. The high heritabilities and favourable genetic correlations suggest these new phenotypes, derived from on-farm antibiotics records, to be promising for inclusion in future pig breeding programs to breed for a decrease in antibiotics usage.

Evaluation of Ventral Laparoscopic Abomasopexy Using Surgical Staples Associated with Suture Material in Dairy Cattle

Background: Displaced Abomasum is known for being on of the main illnesses that affect milking cows. Increase in diagnosis of this illness is due to advancement in diagnosis techniques. Increase in incidence of this illness can be explained by genetic selection of animals with high production, breed systems and changes to the diet with a higher level of protein. For laparoscopic treatment, several surgical changes were performed to optimize the procedure and thus achieve better results. The main purpose of this study was to evaluate applicability of the ventral laparoscopic abomasopexy technique, using surgical clamps attached to the suture thread, to milking cows.Materials, Methods & Results: Six adult cows were placed under anesthesia with isoflurane and placed in dorsal decubitus. Animals were kept with no water for 24 h and no food for 48 h. Four laparoscopic accesses were performed. The first one was created with the intention of inspecting the abdominal cavity and the remaining three for access of surgical instruments. Serous membrane of the abomasum was cauterized, combined with suture threads and placed at the greater abomasal curvature. The free part of suture threads was kept out of the abdominal cavity and after traction of the abomasum against the abdominal wall was tied to the skin. Ultrasound exam was performed for abdominal evaluation after abomasopexy. Anesthesia time and surgery time were recorded and analyzes through average and standard deviation (SD). The average anesthesia time recorded was 94 min (SD 14.63 min) and average surgery time was 51 min (SD 14.71 min). The fasting period was considered adequate, however all animals had to undergo intubation with orogastric tube to drain liquids and gas during the procedure. Four of the six animals had lineal adhesion. Three of the four animals that had adhesion did not keep the abomasum at the retroperitoneal area, however viscera movement was stopped in the abdominal cavity.Discussion: Abomasopexy through laparoscopy is a safe technique, especially when compared with other invasive methods of abomasopexy. However, to perform this type of surgery availability of adequate equipment and a well trained surgical team are required. This study was performed at a surgery room under full anesthesia. In a field situation, the veterinarian can have some difficulties but such adversities must not be considered and impediment for performance of surgery on the field as its performance is possible. Even though surgical clamps were small, they were considered adequate for what was suggested. The applied 0 degree laparoscopic optic presented restrictions for cavity inspection, therefore we believe that an optical lenses with 30 degree angle could facilitate this laparoscopy inspection. To induce greater and more lasting adherence we suggest cauterizing a greater area of the serous membrane of the abomasum. We also suggest not performing this procedure during lactation peak, when fasting and surgery can cause economic losses. Complications associated with this technique could not be avoided. The technique has shown favorable results, but its clinical applicability depends on application on animals subjected to the conditions of a milk production cycle.

Genetic parameters for linear type traits and milk, fat, and protein production in holstein cows in Brazil.

The objective of this study was to estimate genetic and phenotypic parameters for linear type traits, as well as milk yield (MY), fat yield (FY) and protein yield (PY) in 18,831 Holstein cows reared in 495 herds in Brazil. Restricted maximum likelihood with a bivariate model was used for estimation genetic parameters, including fixed effects of herd-year of classification, period of classification, classifier and stage of lactation for linear type traits and herd-year of calving, season of calving and lactation order effects for production traits. The age of cow at calving was fitted as a covariate (with linear and quadratic terms), common to both models. Heritability estimates varied from 0.09 to 0.38 for linear type traits and from 0.17 to 0.24 for production traits, indicating sufficient genetic variability to achieve genetic gain through selection. In general, estimates of genetic correlations between type and production traits were low, except for udder texture and angularity that showed positive genetic correlations (>0.29) with MY, FY, and PY. Udder depth had the highest negative genetic correlation (−0.30) with production traits. Selection for final score, commonly used by farmers as a practical selection tool to improve type traits, does not lead to significant improvements in production traits, thus the use of selection indices that consider both sets of traits (production and type) seems to be the most adequate to carry out genetic selection of animals in the Brazilian herd.

Características de rendimiento y de la carne de canales de ovinos y caprinos alimentados en pastoreo de gramíneas tropicales nativas con o sin suplementación y sacrificados en mataderos locales

Se realizó un estudio dividido en dos partes. En la primera parte, se recolectaron datos de 57 ovinos y 28 caprinos, de diferentes orígenes, sacrificados en mataderos de la región oeste de Puerto Rico para desarrollar una base de datos sobre las características de la canal de pequeños rumiantes (PR) criados bajo el manejo alimentario tradicional. La segunda parte consistió de un ensayo de alimentación en el que corderos (n = 6) y cabritos (n = 6) se asignaron de forma aleatoria dentro de cada especie a uno de dos regímenes de alimentación: con o sin suplementación diaria con alimento concentrado comercial (CC), a razón de 0.9% del peso vivo (PV) en base seca, para evaluar el efecto de los tratamientos sobre la ganancia de peso, características de la canal, y calidad de carne bajo pastoreo de gramíneas tropicales nativas. La base de datos de las características de la canal demostró un porcentaje de rendimiento altamente variado, abarcando de 37 a 46%, y 32 a 38% para ovinos y caprinos, respectivamente, teniendo ambas especies un valor medio similar (P > 0.05). No se observaron diferencias (P > 0.05) en el porcentaje de rendimiento entre sexos. La suplementación con CC aumentó (P < 0.05) por 2,580 g y 40 g la ganancia de peso total y diaria, respectivamente, en corderos en comparación con los no suplementados. En los cabritos las ganancias de peso con suplementación fueron apreciables pero no significativamente mayores (P > 0.05) que en aquellos no suplementados. El porcentaje de rendimiento y los porcentajes de cuartos delantero y trasero no variaron (P > 0.05) entre los tratamientos en ninguna de las especies. Tampoco hubo diferencias (P > 0.05) en pH ni en los porcentajes de humedad, proteína bruta y grasa en el músculo longissimus dorsi entre tratamientos en ninguna de las especies. Esta investigación reveló que es preciso desarrollar un sistema de clasificación local para estandarizar la carne de pequeños rumiantes (CPR) y mejorar su calidad. También es necesaria la selección genética de los animales, así como la investigación sobre fuentes alimentarias alternas menos costosas para la fase de terminación de animales tipo carne para mejorar la cantidad y calidad de la CPR local.

Mitigation of ruminant methane production: current strategies, constraints and future options

Mitigating methane losses from cattle has economic as well as environmental benefits. The aim of this paper is to review the current approaches in relation to associated advantages and disadvantages and future options to reduce enteric methane emission from cattle. Current technologies can be broadly grouped into those that increase productivity of the animal (improved nutrition strategies) so that less methane is produced per unit of meat or milk, and those that directly modify the rumen fermentation so that less methane is produced in total. Data suggest that many of these practices are not appropriate for long term mitigation of methane emissions in ruminants because of their constraints. So it is necessity to develop long term strategies in suppressing methane production. An integrated research investigating animal, plant, microbe and nutrient level strategies would offer a long term solution of methane production. Genetic selection of animals, vaccination, probiotics, prebiotics and plant improvement are the most promising options of all the future approaches discussed. These approaches will reduce enteric methane production without any hazard to animal or environment.

Biotechnology: The Key to Improved Animal Production?

Biotechnology will influence the reproductive performance of cattle in a number of different ways. In animals breeding, embryo transfer has already had a significant impact on the way in which genetic selection of animals is performed. If other technologies such as embryo splitting, in vitro fertilization, cloning, and sex selection are superimposed on conventional embryo transfer, genetic gains will be achieved at an extremely rapid rate. The net result be a rapidly changing animal population in which genetic gains are maximized. Transgenic animals with altered genetic make-up will also have a dramatic effect on animal production. The general introduction of such animals will be slow and the cost to produce them will be enormous, as conventional selection and progeny testing will be needed to ensure that the "new" introduced genes are functional and do not have detrimental side effects. Simple, sensitive assays of hormones and proteins developed using biotechnology will aid in the monitoring of reproductive performance of animals.