Do newborn lambs with black and white hair-coats in an equatorial semi-arid environment maintain homeothermy?

We assessed newborn lambs from two hair-coat sheep breeds, the black Santa Ines (n = 29) and white Dorper (n = 26), to determine how they behaviourally and physiologically respond to the prevailing thermal conditions in an equatorial semi-arid environment. Measurements of hair-coat surface temperature, rectal temperature and the lambs' exposure to sun were recorded across the first 24 h of life every hour, after the lambs had received colostrum. Lambs and ewes were kept in a lambing pen and could freely move between a shaded area or be exposed to sun. During the study period, the air temperature ranged between 20 ºC and 34 ºC. When exposed to sun, lambs and ewes could experience as much as 1200 W m-2 of solar irradiance. Santa Ines lambs exhibited higher (highest density interval at 95%, HDI) hair-coat surface temperatures than did Dorper lambs. Overall, both Santa Ines and Dorper lambs sustained homeothermy, with a mean rectal temperature ranging from 38.7 ºC to 39.1 ºC between night and daytime phase, and a mean amplitude of ~ 0.8 ºC. Nevertheless, from 10:00 to 15:00, some lambs were found to be moderately hyperthermic. Five Santa Ines and three Dorper lambs had rectal temperatures above 40 ºC, and one Santa Ines lamb, while exposed to sun, had a rectal temperature of 41.3 ºC. Over this time period, lambs were more likely to move to shade (HDI at 95%). From 00:00 to 06:00, despite the air temperature being lower than the hair-coat surface, favouring high rates of sensible heat loss to the environment, no lamb exhibited signs of hypothermia (rectal temperature < 37.5 ºC). In conclusion, haired newborn lambs coped well with high levels of radiant heat during the daytime and lower temperatures at night. However, providing access to shade during the daytime is important to improve the welfare of newborn lambs delivered in equatorial semi-arid regions.

Polymorphism of mitochondrial DNA in the Brazilian Canindé goat breed.

The success of the geographical distribution of goat populations around the world is a consequence of the adaptive potential of these breeds. Several relevant traits to the success of the species in colonizing different ecosystems (and use by man) evolved before domestication. These features were relevant for the selection of different breeds. Each breed represents a genetic heritage that may be unique and essential for maintaining the species. The objective of this study was to catalog the mtDNA haplotypes of the Brazilian autochthonous Canindé goat breed and to characterize the genetic diversity observed in subpopulations by sequencing a 481-bp fragment corresponding to the first portion of the control region in 178 individuals from 10 herds, sampled in six Brazilian states. The global population displays a total of 29 haplotypes and 56 polymorphic sites. About one-third (10) of the haplotypes were common to all subpopulations while the remaining (19) were exclusive to a single subpopulation. The population exhibited high average haplotype diversity (0.82), with maximum and minimum values of 0.90 and 0.56 in individual subpopulations, respectively. In contrast, nucleotide diversity was 0.014, with maximum and minimum values of 0.020 and 0.004, respectively. The spatial analysis of molecular variance did not detect structure within the Canindé goat breed, and analysis of molecular variance revealed that 88.4% of the variation observed in the population was due to differences among individuals in the same subpopulation. Only 11.4% of the genetic variation referred to differences among subpopulations. About one-third (33.1%) of the individuals within population shared the same haplotype, which may be due not only to the breed developing from a small number of matrilines. The Brazilian autochthonous Canindé breed was classified as haplogroup A, a haplotype predominant in the Europe region.

Genetic diversity and patterns of population structure in Creole goats from the Americas.

Biodiversity studies are more efficient when large numbers of breeds belonging to several countries are involved, as they allow for an in-depth analysis of the within- and between-breed components of genetic diversity. A set of 21 microsatellites was used to investigate the genetic composition of 24 Creole goat breeds (910 animals) from 10 countries to estimate levels of genetic variability, infer population structure and understand genetic relationships among populations across the American continent. Three commercial transboundary breeds were included in the analyses to investigate admixture with Creole goats. Overall, the genetic diversity of Creole populations (mean number of alleles = 5.82 ± 1.14, observed heterozygosity = 0.585 ± 0.074) was moderate and slightly lower than what was detected in other studies with breeds from other regions. The Bayesian clustering analysis without prior information on source populations identified 22 breed clusters. Three groups comprised more than one population, namely from Brazil (Azul and Graúna; Moxotó and Repartida) and Argentina (Long and shorthair Chilluda, Pampeana Colorada and Angora-type goat). Substructure was found in Criolla Paraguaya. When prior information on sample origin was considered, 92% of the individuals were assigned to the source population (threshold q ≥ 0.700). Creole breeds are well-differentiated entities (mean coefficient of genetic differentiation = 0.111 ± 0.048, with the exception of isolated island populations). Dilution from admixture with commercial transboundary breeds appears to be negligible. Significant levels of inbreeding were detected (inbreeding coefficient > 0 in most Creole goat populations, P < 0.05). Our results provide a broad perspective on the extant genetic diversity of Creole goats, however further studies are needed to understand whether the observed geographical patterns of population structure may reflect the mode of goat colonization in the Americas.

Influence of the climatic environment and duration of labor on the mother-offspring interaction in Morada Nova sheep.

The objective of this study was to confirm the influences of stress from labor and climate on the formation of the mother-offspring bond in Morada Nova sheep in the first 2 h after delivery or at the moment of the first suckling of the newborn. The data were collected from 80 Morada Nova ewes (25 primiparous and 55 multiparous) and their lambs in 2 periods of the year. On the basis of the average length of parturition and the black globe temperature-humidity index (BGTHI) at the time of the birth, the ewes were grouped into 3 classes corresponding to the length of parturition, classified as short (less than 15 min), medium (between 15 and 30 min), or long (more than 30 min). Similarly, the BGTHI at the moment of birth was classified into 1 of 3 ranges: low (less than 65), intermediate (greater than 65 but less than 80), and high (greater than 80). For the characterization of mother-offspring behavior, evaluations were performed in the first 2 h after birth or until the moment of the first suckling of the newborn. Maternal factors such as maternal grooming, facilitating sucking, frequency of low-pitched bleats, and latency to groom were recorded. For the lamb, attempts to seek the udder, the frequency of low-pitched bleats, latency to first reaction, latency to stand, and latency to suckle were recorded. The lambs were slower (P < 0.05) to stand and suckle when they were born in conditions of a BGTHI below 65. The latencies to stand and suckle were greater (P < 0.05) in newborn lambs born during labor that took more than 30 min. For maternal behaviors, activities such as maternal grooming and the facilitation of suckling were greater (P < 0.05) during the time periods with higher bioclimatic index values. Moreover, the dams cleaned or licked (maternal grooming) the newborns for a lower percentage of time (P < 0.05) when the labor lasted longer than 30 min. From the present study, it can be concluded that newborn Morada Nova lambs are slower to stand and suckle when born under BGTHI conditions below 65. Furthermore, prolonged labor harms the mother-offspring bond, especially in terms of the dam's ability to clean (maternal grooming) her lamb's body and facilitate its first suckling.

Aspectos ambientais e genéticos da prolificidade em caprinos utilizando modelos bayesianos de limiar e linear / Environmental and genetic aspects of litter size in goats using linear and threshold bayesian models

Foram estimados os componentes de variância e os parâmetros genéticos da característica prolificidade, utilizando-se inferência bayesiana sob modelo animal linear e de limiar. A prolificidade de cabras mestiças foi estudada com informações referentes ao período de oito anos consecutivos. As análises foram realizadas com cadeias de 500.000 ciclos. Considerou-se burn-in dos 15.000 valores iniciais, sendo tomados valores a cada 250 ciclos, para se obter a distribuição a posteriori com 1.940 amostras. Os efeitos do mês de cobrição e da ordem de parto e o efeito linear do peso à cobrição foram significativos. As herdabilidades foram de 0,03 e 0,18 para o modelo linear e o modelo de limiar, respectivamente. O uso do modelo de limiar mostrou-se adequado, produzindo estimativas superiores acerca dos parâmetros estimados.

Variance components and genetic parameters of the litter size trait, using Bayesian inference under linear and threshold animal model were estimated. The litter size of crossbred goats was studied with information regarding a period of eight consecutive years. Analyses were performed with 500,000 cycle chains. The burn-in of the 15,000 baseline values was considered and these were taken every 250 cycles to obtain a posteriori distribution with 1,940 effective samples. Statistical analyses showed that the effects of coverage month, delivery order and linear effect of weight on coverage were significant. The heritabilities were 0.03 and 0.18 for linear and threshold models respectively. The threshold model proved to be suitable, producing higher estimates regarding the estimated parameters.

Drift across the Atlantic: genetic differentiation and population structure in Brazilian and Portuguese native goat breeds.

Brazilian goat breeds are believed to derive mainly from animals brought by Portuguese settlers since the 16th century. We used microsatellite markers in a sample of 436 animals to study genetic variability and differentiation of the six Portuguese (PT) and six Brazilian (BR) goat breeds currently recognized in the two countries. These breeds were also compared with an outgroup represented by a sample of Alpine (ALP) goats. The effective number of alleles and allelic richness were slightly higher in PT than in BR breeds. The global F(ST) was nearly 0.11 when PT and BR breeds were considered, with a mean pairwise F(ST) of about 0.03 among PT breeds, 0.07 among BR breeds and 0.15 between PT and BR breeds. The dendrogram illustrating relationships between populations and the correspondence analysis indicate the existence of two very distinct clusters, corresponding to the countries of origin of the breeds studied, which are nearly equidistant from the Alpine outgroup. The analysis with structure confirmed the separation between PT and BR breeds but suggests that some BR breeds, especially Graúna and Canindé, may share a common ancestry with PT breeds. The divergence observed between PT and BR breeds may result from founder effects and genetic drift but could also reflect the introduction in Brazil of goats originating from other regions, e.g., West Africa.