Ruminant livestock are important sources of human food and global greenhouse gas emissions. Feed degradation and methane formation by ruminants rely on metabolic interactions between rumen microbes and affect ruminant productivity. Rumen and camelid foregut microbial community composition was determined in 742 samples from 32 animal species and 35 countries, to estimate if this was influenced by diet, host species, or geography. Similar bacteria and archaea dominated in nearly all samples, while protozoal communities were more variable. The dominant bacteria are poorly characterised, but the methanogenic archaea are better known and highly conserved across the world. This universality and limited diversity could make it possible to mitigate methane emissions by developing strategies that target the few dominant methanogens. Differences in microbial community compositions were predominantly attributable to diet, with the host being less influential. There were few strong co-occurrence patterns between microbes, suggesting that major metabolic interactions are non-selective rather than specific.

Ruminant livestock are important sources of human food and global greenhouse gas emissions. Feed degradation and methane formation by ruminants rely on metabolic interactions between rumen microbes and affect ruminant productivity. Rumen and camelid foregut microbial community composition was determined in 742 samples from 32 animal species and 35 countries, to estimate if this was influenced by diet, host species, or geography. Similar bacteria and archaea dominated in nearly all samples, while protozoal communities were more variable. The dominant bacteria are poorly characterised, but the methanogenic archaea are better known and highly conserved across the world. This universality and limited diversity could make it possible to mitigate methane emissions by developing strategies that target the few dominant methanogens. Differences in microbial community compositions were predominantly attributable to diet, with the host being less influential. There were few strong co-occurrence patterns between microbes, suggesting that major metabolic interactions are non-selective rather than specific.

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SUMMARY: Most Chilean sheep stock comprises different degrees of crossbreeding over Corriedale breed. A common absorbent crossbreeding has been Australian Merino over Corriedale which, in many cases, has not been complete. The aim of this study was to evaluate the process of morphology differentiation and structural functionality of Corriedale ewes undergoing incomplete absorbent crossbreeding which was carried out in order to create an animal with a new morphology. A total of four hundred adult ewes were measured; two hundred belonging to the incomplete crossbreeding, and two hundred from the two original breeds (one hundred Corriedale and one hundred Australian Merino ewes). All measured ewes were randomly selected. Fourteen body measurements were recorded and nine body indexes were calculated for each ewe. Results show that a new biotype has been created from the absorbent crossbreeding of Corriedale by Australian Merino, which produced ewes with a clear morphological and structural functionality differentiation as compared to the two original breeds. The new body format shows morphostructural variability coefficients that are similar to those found on other formally recognized sheep breeds.

How to cite this paper: Ramírez-Retamal, J., et al. AbstractChilote sheep are a native breed from Chiloé Archipelago in the southern Chile. They are descendants from sheep originally introduced by the Spaniards in the 1600s, and then evolved in a harsh environment in relative isolation from the continent. There is little information about the quality of the meat of the Chilote lambs (Ch). The objective of this study was to compare the quality of Ch lamb meat with two types of marginal pastures. The two treatments were: 1) Ch lambs, naturalized grassland (n = 13) and 2) Ch lambs, rangeland (n = 11). Rangeland is composed of both grasses and native shrubs. All lambs were kept with their mothers until slaughter at 90 days of age. Instrumental color, shear force, pH levels, and chemical and fatty acid content were analyzed. The pasture type did affect the results, given that Ch lambs fed on naturalized pasture had a lower shear force and higher intramuscular fat levels whereas Ch lambs fed on rangeland pasture showed higher percentages of n-3, n-6 fatty acids and Polyunsaturated fatty acids. However, the concentrations of fatty acids were similar in both groups. The results indicated some evidences that the type of pasture of Chiloe archipelago confers specific differences of quality that could form the basis to generate a premium product.

Morphological traits of the whole udder (circumference, width, height, and length), teats (angle, length and width), udder cistern (teat opening and cistern height), and milk yield were measured over one lactation in a total of 18 ewes (nine Chilota and nine Suffolk Down sheep) belonging to the same experimental flock (Centro Experimental INIA Butalcura, Chiloé, Chile). Analysis of variance showed significant effects for breed, sheep within breed, and stage of lactation. Chilota ewes evidenced greater udder circumference (433 mm), udder length (86 mm), teat opening (96º), and milk yield (947 mL d -1 ) than Suffolk Down ewes (410 mm, 77 mm, 93º, and 559 mL d -1 , respectively). Udder circumference, udder width, udder length, cistern height and teat size significantly decreased throughout lactation. Repeatabilities of all traits were between 0.17 and 0.60; the highest repeatability was for udder circumference. This trait is easy to measure and had a discriminatory value for breed differentiation. In conclusion, Chilota sheep had a dairy aptitude greater than Suffolk Down sheep and similar to Spanish and Mediterranean dairy sheep breeds at beginning of their breeding programs.

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ResumenCon este artículo se trata de resaltar las características distintivas del ovino criollo Chilote (OCH) para su conocimiento y utilización como recurso genético animal de gran adaptación a las condiciones del archipiélago de Chiloé, ubicado en la zona sur de Chile. Se describen las características geomórficas del archipiélago, el origen histórico y cultural que rodea este recurso animal, su estructura genética, sus características morfológicas y productivas, así como los sistemas de producción en los cuales se utiliza.Palabras clave: ovinos, recursos genéticos, producción animal Summary This article describes the characteristics of the Chilote breed of sheep (OCH) as a genetic animal resource which is highly adapted to the conditions of the Chiloé archipelago in the south of Chile. The article describes the geomorphological features of the archipelago, the historical and cultural origins of the Chilote breed, its genetic structure, its morphological and productive characteristics, and the systems of production in which it is used. RésuméAvec cet article on a essayé de souligner les caractéristiques distinctives de l'ovin créole Chilote (OCH) pour sa connaissance et utilisation comme ressource génétique animale de grande adaptation aux conditions de l'archipel de Chiloé, situé dans la zone sud du Chili. On décrit les caractéristiques géomorphologiques de l'archipel, l'origine historique et culturelle qui entoure cette ressource animale, sa structure génétique, ses caractéristiques morphologiques et productives, ainsi que les systèmes de production dans lesquels elle est utilisée.