Germán D. Mendoza-Martínez

Dual purpose cattle production in Mexico

Cattle production is one of the most important livestock activities in the rural areas of Mexico, with most of the national territory dedicated to it, in addition to the use of the most agricultural supplies and forages resources, as well as agricultural and agro-industrial by-products. Mexico is placed among the ten first meat and milk producer countries worldwide, being the Mexican tropical zone one of the main suppliers of such products. One of the main milk sources is the dual purpose cattle, such systems can be described as those that produce milk (daily milking) and meat (calf after weaning), on every productive cycle. They are mainly located in developing regions and characterized by using low-technology and in poor environments, consequently productive levels are considered low. Milk is destined for self-consumption or for sale at local markets and calf after weaning is sold at local feedlots or for export. Regarding to the little information available about the dual purpose systems, the present work is intended to discuss the main characteristics of cattle production in dual purpose systems in Mexico.

The Jaguar (Panthera onca) in San Luis Potosí, Mexico

Abstract Geographic range of the jaguar (Panthera onca) in Mexico has decreased due to illegal hunting, loss of prey, and loss of habitat. No survey of jaguars has been conducted in San Luis Potosí since 1953, despite potentially suitable habitat in the Sierra Madre Oriental. During May 2006–March 2008, we conducted 22 field surveys, including interviews of local officials, residents, landowners, and hunters from 42 communities, and searched for tracks near each location where jaguars were reported in the Huasteca Region of the Sierra Madre Oriental of San Luis Potosí. We obtained 34 records of jaguars, 28 considered as recent records comprising ≥12 individuals and 6 historic records. Jaguars were recorded in oak forest (31.1% of records), tropical deciduous forest (28.1%), cloud forest (12.5%), tropical forest (12.5%), piedmont scrub (9.4%), pine-oak forest (3.1%), and along a border between a sugar cane plantation and tropical forest (3.1%). Locations were 150–2,400 m in elevation. We documented presence of diverse prey and four other species of felids. We generated a distribution map for jaguars and estimated loss of forests for 1970–2000. Geographical distribution of jaguars in San Luis Potosí extends north (22°30′N) to the municipality of El Naranjo, south (21°24′N) to the municipality of Xilitla, east (98°54′W) to the municipality of Ciudad Valles, and west (99°34′W) to the municipality of Rayón. The distribution comprises the subprovince of the Gran Sierra Plegada, Carso Huasteco, and Sierra del Abra Tanchipa of the Sierra Madre Oriental. Given the number of records and quality of remaining habitat, the Sierra Madre Oriental in San Luis Potosí should be considered as a high priority for long-term conservation of jaguars in Mexico.

Genetic diversity and genetic structure of an endemic Mexican Dusky Rattlesnake (Crotalus triseriatus) in a highly modified agricultural landscape: implications for conservation

Abstract It is necessary to determine genetic diversity of fragmented populations in highly modified landscapes to understand how populations respond to land-use change. This information will help guide future conservation and management strategies. We conducted a population genetic study on an endemic Mexican Dusky Rattlesnake (Crotalus triseriatus) in a highly modified landscape near the Toluca metropolitan area, in order to provide crucial information for the conservation of this species. There was medium levels of genetic diversity, with a few alleles and genotypes. We identified three genetically differentiated clusters, likely as a result of different habitat cover type. We also found evidence of an ancestral genetic bottleneck and medium values of effective population size. Inbreeding coefficients were low and there was a moderate gene flow. Our results can be used as a basis for future research and C. triseriatus conservation efforts, particularly considering that the Trans-Mexican Volcanic Belt is heavily impacted by destructive land-use practices.

Effects of two fibrolytic enzyme mixtures on growth performance, digestion and ruminal fermentation in lambs fed corn stover based diets.

The objective of this study was to compare the effects of two fibrolytic enzyme mixtures (Fibrozyme and Promote) on growth performance, digestion and ruminal fermentation in lambs fed corn stover based diets. Forty-two crossbred (Black Belly×Dorper) lambs (20±1.6 kg) were randomly assigned to three treatments defined as Control (no enzymes), Fibrozyme (Alltech, Nicholasville, KY, USA), and Promote (Cargill Corp., Minneapolis, MN, USA). Growth performance evaluation lasted 55 days. On day 55, rumen fluid samples were obtained. Both Fibrozyme and Promote improved growth performance, feed conversion and digestion as compared to Control. Enzymes increased total volatile fatty acids, but only Fibrozyme increased molar proportion of propionate, decreased molar proportion of butyrate, and reduced the acetate: propionate ratio. It is concluded that both Fibrozyme and Promote improved growth performance and digestion in lambs fed high-forage diets.

Feeding Interactions in an Assemblage of Terrestrial Carnivores in Central Mexico

BackgroundWe evaluated the strategies of resources partitioning among species, dietary overlap and niche breadth in an assemblage of carnivores integrated by top predators (Puma concolor and Panthera onca) and mesopredators (Leopardus pardalis, Leopardus wiedii, Puma yagouaroundi, Nasua narica and Urocyon cinereoargenteus). The aim of this study was to investigate the mechanisms explaining the coexistence among species at a temperate zone in central Mexico.ResultsWe collected 259 scats of carnivores and identified 45 food items. The analysis showed the common consumption of mammals in the assemblage, and the correspondence analysis showed three guilds: 1) top predators associated with the use of medium-sized mammals and the exclusive consumption of large mammals, 2) carnivore mesopredators associated with the consumption of small mammals and birds and 3) omnivore mesopredators associated with the consumption of arthropods and plants. The dietary overlap analysis indicated a low overlap between guilds and a high overlap within them. Top predators were specialist foragers, whilst the carnivore mesopredators showed generalist consumption.ConclusionsThe coexistence in this carnivore assemblage seems to be related to body size, morphology and prey segregation because such characteristics suggest the presence of three guilds. We observed high dietary overlap within guilds and resource partitioning between guilds.

Comparison of in vitro degradation of elephant grass and sugarcane by exogenous fibrolytic enzymes

The objective of this study was to compare, under in vitro conditions, the kinetics of organic matter (OM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) degradation of elephant grass and sugarcane. Sugarcane had higher degradation than elephant grass. Enzymes increased soluble fraction, potential and total degradation of OM and NDF of sugarcane and elephant grass. The NDF degradation rate of elephant grass and sugarcane was also improved by enzymes. Enzymes increased OM degradation rate only of sugarcane. Kinetic of ADF degradation only of sugarcane was increased by enzymes. It is concluded that exogenous fibrolytic enzymes improved degradation of sugarcane, and OM and NDF degradation of elephant grass.

Genetic variability and structure of jaguar (Panthera onca) in Mexican zoos

Genealogical records of animals (studbook) are created to avoid reproduction between closely related individuals, which could cause inbreeding, particularly for such endangered species as the Panthera onca (Linnaeus, 1758). Jaguar is the largest felid in the Americas and is considered an important ecological key species. In Mexico, wild jaguar populations have been significantly reduced in recent decades, and population decline typically accompany decreases in genetic variation. There is no current census of captive jaguars in Mexico, and zoos do not follow a standardized protocol in breeding programs based on genetic studies. Here, we emphasise the importance of maintaining an adequate level of genetic variation and propose the implementation of standardised studbooks for jaguars in Mexico, mainly to avoid inbreeding. In addition, achieving the aims of studbook registration would provide a population genetic characterisation that could serve as a basis for ex situ conservation programmes.

Genetic structure and diversity in an isolated population of an endemic mole salamander (Ambystoma rivulare Taylor, 1940) of central Mexico

Human activities are affecting the distribution of species worldwide by causing fragmentation and isolation of populations. Isolation and fragmentation lead to populations with lower genetic variability and an increased chance of inbreeding and genetic drift, which results in a loss of biological fitness over time. Studies of the genetic structure of small and isolated populations are critically important for management and conservation decisions. Ambystoma rivulare is a micro-endemic Mexican mole salamander from central Mexico. It is found in the most ecologically disturbed region in Mexico, the Trans-Mexican Volcanic Belt. The goal of this study of the population genetics of the micro-endemic mole salamander was to provide information to be used as a basis for future research and conservation planning of this species and other species of the Ambystoma genus in Mexico. The structural analysis found two subpopulations, one for each river sampled, with no signs of admixture and very high levels of genetic differentiation. Medium to high levels of heterozygosity and few alleles and genotypes were observed. Evidence of an ancestral genetic bottleneck, low values of effective population size, small inbreeding coefficients, and low gene flow were also found.

Influence of supplemental canola or soybean oil on milk yield, fatty acid profile and postpartum weight changes in grazing dairy goats

Objective This experiment was designed to evaluate the effect of supplementation with soybean or canola oil on milk production and the composition of long chain fatty acids as well as weight changes in the goats and their kids. Methods Thirty nine mulitparous crossed Alpine×Nubian goats (initial body weight [BW] 43.5±1.7 kg) from the day of parturition were assigned to the treatments: grazing control (n = 15); grazing plus 20 mL/goat/d of supplemental soybean oil (n = 12); and grazing plus 20 mL/goat/d of supplemental canola oil (n = 12) from November 26, 2014 to March 7, 2015. The planned contrasts were: CI (control vs supplemented with oils); CII (soybean vs canola oil) to compare the treatment effects. Results The vegetable oil supplementation reduced weight losses in lactating goats (CI: −0.060 vs 0.090 kg/d; p = 0.03) but did not improve milk production or affect kids’ growth. The content of C4, C6, C8, C10, C11, C14, and C18:1n9t in the milk was increased (p<0.05) with respect to control. However, C12, C14, C16, C18, C18:1n9c, C18:2n6c, and C18:3n3 were reduced (p<0.05) in supplemented goats. Conjugated linoleic acid (CLA) was increased (p<0.05) in goats supplemented with oils compared to the control group. Conclusion Supplementation with 20 mL/d of soybean or canola oil did not affect milk production or kids’ performance; however, it increased CLA concentration and reduced the reduced weight losses in lactating goats.

Genetic variability and structure of an isolated population of Ambystoma altamirani, a mole salamander that lives in the mountains of one of the largest urban areas in the world

Amphibians are globally threatened by habitat loss and fragmentation; species within the order Ambystoma are not the exception, as there are 18 species of mole salamanders in México, of which 16 are endemic and all species are under some national or international status of protection. The mole salamander, Ambystoma altamirani is a microendemic species, which is distributed in central México, within the trans-Mexican volcanic belt, and is one of the most threatened species due to habitat destruction and the introduction of exotic species. Nine microsatellite markers were used to determine the genetic structure, genetic variability, effective population size, presence of bottlenecks and inbreeding coefficient of one population of A. altamirani to generate information which might help to protect and conserve this threatened species. We found two genetic subpopulations with significant level of genetic structure (