Relationships between integumental characteristics and thermoregulation in South American camelids

Whole genome sequencing analysis of alpaca suggests TRPV3 as a candidate gene for the suri phenotype

BACKGROUND

Alpaca is a domestic South American camelid probably arising from the domestication of two wild camelids, the vicugna and the guanaco. Two phenotypes are described for alpaca, known as huacaya and suri. Huacaya fleece is characterized by compact, soft, and highly crimped fibers, while suri fleece is longer, straight, less crimped, and lustrous. The gene variants determining these phenotypes are still unknown, although previous studies suggested a dominant inheritance of the suri. Based on that, the aim of this study was the identification of the gene variants determining alpaca coat phenotypes through whole genome sequencing (WGS) analysis.

RESULTS

The sample used includes two test-cross alpaca families, suri × huacaya, which produced two offspring, one with the suri phenotype and one with the huacaya phenotype. The analyzed sample was expanded through the addition of WGS data from six vicugnas and six guanacos; this because we assumed the absence of the gene variants linked to the suri phenotype in these wild species. The analysis of gene variant segregation with the suri phenotype, coupled with the filtering of gene variants present in the wild species, disclosed the presence in all the suri samples of a premature termination codon (PTC) in TRPV3 (transient receptor potential cation channel subfamily V member 3), a gene known to be involved in hair growth and cycling, thermal sensation, cold tolerance and adaptation in several species. Mutations in TRPV3 were previously associated with the alteration of hair structure leading to an impaired formation of the hair canal and the hair shaft in mouse. This PTC in TRPV3, due to a G > T substitution (p.Glu475*), results in a loss of 290 amino acids from the canonical translated protein, plausibly leading to a physiological dysfunction.

CONCLUSION

The present results suggest that the suri phenotype may arise from a TRPV3 gene variant which may explain some of the suri features such as its longer hair fibre with lower number of cuticular scales compared to huacaya.

Heat dissipation in subterranean rodents: the role of body region and social organisation

The relatively warm and very humid environment of burrows presents a challenge for thermoregulation of its mammalian inhabitants. It was found that African mole-rats dissipate body heat mainly through their venter, and social mole-rats dissipate more body heat compared to solitary species at lower temperatures. In addition, the pattern of the ventral surface temperature was suggested to be homogeneous in social mole-rats compared to a heterogeneous pattern in solitary mole-rats. To investigate this for subterranean rodents generally, we measured the surface temperatures of seven species with different degrees of sociality, phylogeny, and climate using infrared thermography. In all species, heat dissipation occurred mainly through the venter and the feet. Whereas the feet dissipated body heat at higher ambient temperatures and conserved it at lower ambient temperatures, the ventral surface temperature was relatively high in all temperatures indicating that heat dissipation to the environment through this body region is regulated mainly by behavioural means. Solitary species dissipated less heat through their dorsum than social species, and a tendency for this pattern was observed for the venter. The pattern of heterogeneity of surface temperature through the venter was not related to sociality of the various species. Our results demonstrate a general pattern of body heat exchange through the three studied body regions in subterranean rodents. Besides, isolated individuals of social species are less able to defend themselves against low ambient temperatures, which may handicap them if staying alone for a longer period, such as during and after dispersal events.

Camelids: new players in the international animal production context

The Camelidae family comprises the Bactrian camel (Camelus bactrianus), the dromedary camel (Camelus dromedarius), and four species of South American camelids: llama (Lama glama), alpaca (Lama pacos) guanaco (Lama guanicoe), and vicuña (Vicugna vicugna). The main characteristic of these species is their ability to cope with either hard climatic conditions like those found in arid regions (Bactrian and dromedary camels) or high-altitude landscapes like those found in South America (South American camelids). Because of such interesting physiological and adaptive traits, the interest for these animals as livestock species has increased considerably over the last years. In general, the main animal products obtained from these animals are meat, milk, and hair fiber, although they are also used for races and work among other activities. In the near future, climate change will likely decrease agricultural areas for animal production worldwide, particularly in the tropics and subtropics where competition with crops for human consumption is a major problem already. In such conditions, extensive animal production could be limited in some extent to semi-arid rangelands, subjected to periodical draughts and erratic patterns of rainfall, severely affecting conventional livestock production, namely cattle and sheep. In the tropics and subtropics, camelids may become an important protein source for humans. This article aims to review some of the recent literature about the meat, milk, and hair fiber production in the six existing camelid species highlighting their benefits and drawbacks, overall contributing to the development of camelid production in the framework of food security.

Environmental factors influencing guanaco distribution and abundance in central Patagonia, Argentina

Context The guanaco is the largest wild herbivore inhabiting the Patagonian steppes. Since the end of the 19th Century, it has suffered a progressive decline in numbers owing to poaching and unregulated hunting because of on an assumed competition with sheep. Unfortunately, there has never been a management program for guanaco populations in Argentine Patagonia. Consequently, the guanaco is still considered a pest species by ranchers and has never been considered profitable in the range management model implemented in Patagonia. Aims The present article updates the distribution limits of guanaco and estimate its abundance across Chubut, a large province of Patagonia, Argentina. The relative effects of several environmental and anthropogenic factors on guanaco distribution are also assessed. Methods Road surveys (7010km) and species distribution modelling were used to build a habitat suitability model and a distribution map. A distance sampling method was used to estimate guanaco population densities and size. The survey effort required to monitor population trends in this region was also calculated. Key results According to the best habitat suitability model, guanaco distribution decreased with altitude and primary productivity, as measured by Normalised Difference Vegetation Index (NDVI), and increased with the distance to the nearest urban centre and oil field. Guanaco distribution showed a clear geographical pattern in Chubut, with low to medium occurrence probability towards the west and higher values towards the east. Guanaco population size was estimated as 657304 individuals (95% CI 457437 to 944059), with a mean density of 2.97 guanacos km–2. Finally, through simulations of guanaco monitoring, it was estimated that an annual survey effort of 10 to thirty 30-km road transects is needed to detect with confidence a significant population decrease or increase over the next 6 or 10 years. Conclusions The habitat suitability map presented herein highlights areas with high guanaco densities in Chubut, where it would be possible to identify ranches suitable for performing profitable herding and shearing experiences. Implications The maps of guanaco distribution and density, as well as the survey effort required to monitor population trends, may be used to inform decisions concerning the sustainable use of this species.

Characterization of the hair coat of the Polish Konik and Hucul pony focusing on the physical features and histological structure of different hair types

The aim of the study was a comparative analysis of the hair coat of the Polish Konik and Hucul pony, focusing on the histological structure and physical parameters of the hair. Hair samples were obtained from 20 mares—10 of each breed. They were collected in winter, from the side of barrel, the mane, the tail, and front and rear fetlock. The hairs from the barrel were divided into overhair and underhair fractions. A higher percentage of underhair (about 70%) as compared to overhair (30%) was noted in both breeds. The overhair of the Polish Konik was about 50% longer than that of the Hucul pony, while the length of underhair did not differ between breeds. Both the overhair and the underhair of the Polish Konik were about 25% thicker than that of the Hucul pony. Elongation of particular types of hair did not differ significantly between the breeds. It was lowest for fetlock hair (about 45%) and highest for mane hair (about 55%). The histological structure of the cuticle layer of the hair did not differ between breeds.

Effect of shearing on water turnover and thermobiological variables in German Blackhead mutton sheep

Current equations for estimating water requirements in sheep do not differentiate between shorn and unshorn sheep. Furthermore, the effect of shearing on thermoregulative responses in sheep has not been adequately studied under temperate environmental conditions. Therefore, the present study was conducted to investigate the effect of wool coverage on water turnover in relation to thermoregulation in sheep by using the deuterium dilution technique to predict total water intake before and after shearing. Physiological responses, such as water turnover, surface temperature, and rectal temperature, as well as drinking behavior of sheep were also evaluated. Fourteen nonlactating German Blackhead mutton ewes were randomly allocated into 2 groups: a control group (n = 7) that was already shorn, and a treatment group (n = 7) that was left unshorn (wool length: 10.6 ± 1.2 cm). Individual feed and water intakes were recorded throughout the experiment (d 1 to 71). Two weeks after measurements commenced (d 15), treatment sheep were shorn. Water intake was estimated twice for 2 consecutive weeks by using deuterium dilution techniques (d 1 to 15 and d 57 to 71). Ambient temperature (T(a)), relative humidity, and respiratory rate were measured daily, whereas BW, rectal and animal surface temperatures (using infrared thermography), and wool length were measured weekly. In the first 2 wk, when treatment sheep were unshorn, treatment and control ewes differed (P < 0.05) in DMI (52 ± 4 vs. 59 ± 4 g·kg(-0.75)·d(-1)), water intake (165 ± 17 vs. 134 ± 18 g·kg(-0.75)·d(-1)), respiratory rate (66 ± 5 vs. 31 ± 4 breath/min), rectal temperature (39.3 ± 0.2 vs. 38.8 ± 0.1°C), and surface temperatures (body side: 19.3 ± 0.3 vs. 24.5 ± 0.6°C; leg: 25.8 ± 2.4 vs. 27.4 ± 1.6°C). However, after shearing, these differences partly disappeared. The same trend in water intake between groups was confirmed using the isotope dilution technique. We found a significant relationship between T(a) and water intake, respiratory rate, and body surface temperatures. Even under temperate conditions (T(a) < 28°C), shearing significantly reduced core body temperature, water intake, and respiratory rate in German Blackhead mutton sheep, thus indicating heat stress in fleeced animals, which should be considered when determining the optimal shearing time in sheep as well as when estimating water requirements.