Estimation of genetic parameters for reproductive indices in sheep.

This study aimed to estimate two reproductive efficiency indices in sheep based on the ratio between litter weight (at birth and weaning) and dam weight, as well as their genetic parameters. Phenotypic and pedigree data comprising the period from 1990 to 2018 were obtained from the Santa Inês sheep database of Embrapa Tabuleiros Costeiros. For estimation of the genetic parameters of the indices, a repeatability model was applied in single- and two-trait analyses by a Bayesian approach. The mean reproductive efficiency index was 0.069 ± 0.0163 and 0.43 ± 0.0955 at birth and weaning, respectively. These values indicate that, on average, ewes give birth to 69 g of lamb per kg body weight and wean 430 g of lamb per kg body weight. Described here for the first time, the heritability estimate obtained in single- and two-trait analyses was 0.24 for the index based on birth weights and ranged from 0.13 to 0.15 for the index based on weaning weights. The estimates indicate the possibility of genetic gain by selection and are similar to those reported for reproductive traits in sheep, representing an option for selection criterion. The genetic correlation between indices was positive and moderate (0.26). The repeatability estimates were high (0.49 for the birth weight index and 0.71 for the weaning weight index). These values indicate good prediction of future performance with few observations. The weaning weight index might be a good culling criterion of females.

Bioclimatic thermal stress indices and their relationships with andrological characteristics in hair rams.

This study evaluated relationships among reproductive parameters and the bioclimatic indices: temperature and humidity index (THI), equivalent temperature index (ETI), black globe temperature and humidity index (BGTHI), and thermal comfort index (TCI), during the first 45 days of spermatogenesis (SP-45) and during the 15 days of sperm transit through the epididymis (STP-15) that preceded the reproductive assessments (ReA). Such information is useful in determining the optimal breeding season in Northeast Brazil. Santa Inês rams (n = 25) underwent two ReA in three periods of the year (D-P = dry; R-P = rainy and RD-P = rainy/dry transition), and the bioclimatic indices were calculated at the corresponding SP-45 and STP-15 timepoints prior to each ReA. Sperm kinetic parameters in D-P were depressed compared to R-P and RD-P (P < 0.05). The index values had an antagonistic relationship with most parameters and regression analysis demonstrated that the BGTHI and the TCI had a negative association with the progressive motility, curvilinear, straight line, and average path velocities, and a positive association with slow sperm in the ejaculate in SP-45 and STP-15 phases (P < 0.01). Semen quality kinetics is affected throughout the year by the environment and it is apparent that it is impaired in D-P and better in R-P and RD-P seasons. The BGTHI and TCI measured in the sperm production phase classified the environment most coherently and presented better association with the behavior of sperm kinetics.

Incorporation of Biotechnologies into Gene Banking Strategies to Facilitate Rapid Reconstitution of Populations.

National animal gene banks that are responsible for conserving livestock, poultry, and aquatic genetic resources need to be capable of utilizing a broad array of cryotechnologies coupled with assisted reproductive technologies to reconstitute either specific animals or populations/breeds as needed. This capability is predicated upon having sufficient genetic diversity (usually encapsulated by number of animals in the collection), units of germplasm or tissues, and the ability to reconstitute animals. While the Food and Agriculture Organization of the United Nations (FAO 2012, 2023) developed a set of guidelines for gene banks on these matters, those guidelines do not consider applications and utilization of newer technologies (e.g., primordial germ cells, cloning from somatic cells, embryo transfer, IVF, sex-sorted semen), which can radically change how gene banks collect, store, and utilize genetic resources. This paper reviews the current status of using newer technologies, explores how gene banks might make such technologies part of their routine operations, and illustrates how combining newer assisted reproductive technologies with older approaches enables populations to be reconstituted more efficiently.

Association between different soy lecithin-based extenders and freezing rates in ram semen cryopreservation.

The aim of the study was to evaluate the effect of the association between glycine-milk (GM) based extenders made with different concentrations of soy lecithin (SL) and freezing rates (FR) on semen quality after thawing. Pooled semen from rams (n = 12) were diluted in GM extenders with 20% egg yolk (EY-20%) or with different concentrations of SL: 0.5% (SL-0.5%), 1.0% (SL-1.0%), and 2.0% (SL-2.0%). The diluted semen (150 ×106 spermatozoa/0.25 mL) was frozen at three FR of - 10, - 20, and - 60 °C/min, and subsequently thawed and analyzed. Results revealed that EY-20% and SL-2.0% had better kinetic parameters, and showed higher proportions of viable, non-apoptotic, plasma-membrane-intact spermatozoa (A-/PI-) and non-capacitated spermatozoa (F), and had lower acrosome-reacted spermatozoa (AR) in the EY-20% and satisfactory values for SL-2.0% compared to SL-0.5% and SL-1.0% (P < 0.05). The FR at - 20 and - 60 °C/min maintained higher A-/PI- and viable spermatozoa compared to - 10 °C/min. The combination EY-20% and - 60 °C/min showed the highest A-/PI- and F (P < 0.05) and the lowest AR, and it did not differ from the combinations EY-20% at - 20 °C/min and SL-2.0% at - 20 °C/min (P > 0.05). In conclusion, the combination EY-20% and - 60 °C/min, showed the best cryoprotective effects on ram spermatozoa. Changes in spermatozoa after thawing were related to the use of the type of extender, the amounts of the same compound in the extender, and the freezing rates to which they were subjected.

Use of logistic models to evaluate the response of superovulation treatment and embryo production in Santa Inês ewes.

The study aimed to verify the influence of the FecGE mutation in superovulated ewes and to evaluate the probability of logistic models to determine the response capacity of these ewes to superovulatory treatment. Santa Inês ewes (n = 29) were genotyped for the FecGE mutation and separated for their genotype group in carriers of the mutant E allele (FecGE/E, FecG+/E) and non-carrier (FecG+/+) alleles. The ewes underwent hormonal treatment for superovulation. Aside from the genotypes, variables included in the statistical model were reproductive status (empty, early lactation, or late lactation), age (> or < 6 years), and number of births (nulliparous, primiparous, multiparous). The carriers of the mutation could be discriminated from the non-carriers based on the number of corpora lutea, rate of frozen embryos, and fecundity. Recovery rate was significantly higher (P < 0.05) in FecGE/E (94.31%) compared to FecG+/E (63.15%) and FecG+/+ (61.90%) (P < 0.05), whereas fecundity rate of FecG+/+ ewes (50.76%) was significantly higher than FecG+/E (18.96%) and FecGE/E (32.53%) (P < 0.05). We determined in this study that the response to superovulation and embryo production can be discriminated between FecGE/E and FecG+/E ewes in relation to the FecG+/+ genotype. Logistic models that included reproductive status and mutation, or reproductive status and age, or reproductive status and number of births were effective in predicting the response to superovulatory treatment.

Variants in myostatin and MyoD family genes are associated with meat quality traits in Santa Inês sheep.

Myostatin and MyoD family genes play vital roles in myogenesis and this study aimed to identify association of variants in MyoD1, MyoG, MyF5, MyF6, and MSTN genes with meat traits in Santa Inês sheep. A dataset with 44 variants and records of seven meat traits in 192 lambs (pH0, pH24, a*, b*, L*, tenderness assessed by shear force, and water-holding capacity) was used. Single-locus and haplotype association analyses were performed, and the significance threshold was established according to Bonferroni's method. Single-locus analysis revealed two associations at a Bonferroni level, where the variant c.935-185C > G in MyoD1 had an additive effect (-4.31 ± 1.08 N) on tenderness, while the variant c.464 + 185G > A in MyoG had an additive effect (-2.86 ± 0.64) on a*. Additionally, the haplotype replacement GT>AC in MSTN was associated with pH0 (1.26 ± 0.31), pH24 (1.07 ± 0.27), a* (-1.40 ± 0.51), and tenderness (3.83 ± 1.22 N), while the replacement GT > AG in MyoD1 was associated with pH0 (1.43 ± 0.26), pH24 (1.25 ± 0.22), b* (-1.06 ± 0.39), and tenderness (-4.13 ± 1.16 N). Our results have demonstrated that some variants in MyoG, MyF6, MyoD1, and MSTN can be associated with physicochemical meat traits in Santa Inês sheep.

Occurrence, morphology, and morphometry of follicles containing multiple oocytes in FecGE mutant Santa Inês ewes.

This study was conducted to characterize the morphology and morphometry of follicles containing multiple oocytes (MOFs) and determine the association with the FecGE mutation in Santa Inês ewes. Based on the genotypes, 65 ewes were characterized as being homozygous wild-type (n = 25; FecG+/+), heterozygous mutant (n = 27, FecG+/E), and homozygous mutant (n = 13, FecGE/E). The variables evaluated were follicle developmental stage, number of oocytes per follicle, morphology, and morphometry of MOFs. The FecGE mutation did not affect the frequency of MOFs (P > 0.05) (3.0 % in FecG+/+; 3.3 % in FecG+/E; and 3.5 % in FecGE/E). The greater viability (P < 0.05) of MOFs was identified in transitory stage of the FecGE/E (95.0 %) and FecG+/E (90.9 %) when compared to the FecG+/+ genotype (73.3 %). Furthermore, the morphology of transitory follicles with two oocytes was the variable and when evaluated was the most reliable determinant for predicting which ewes had an FecGE mutation. In conclusion, the FecGE mutation did not affect the frequency of MOFs. The ewes with FecGE mutation had a greater frequency of morphologically normal MOFs in the transitory stage. Furthermore, the ewes with the FecGE mutation had a greater likelihood of having MOFs containing two morphologically normal oocytes.

Integration of georeferenced and genetic data for the management of biodiversity in sheep genetic resources in Brazil.

There are few animal germplasm/gene bank collections in Brazil, and basic studies are needed to attend the future internal and external demands from international partners. The aim of this work was to validate a "proof of concept" that integrates spatial (georeferenced data) and genetic data regarding the local of origin from 3518 DNA samples from 17 different genetic groups or breeds of sheep in the Brazilian Germplasm bank. Spatialisation shows that not all genetic groups have samples in the bank, and collection is concentrated in the conservation nuclei spread nationwide. Only 21% of states with a specific breed have samples in the gene bank. The mean number of animals sampled per collection was 32, while the mean distance travelled to collect samples was 262 km from the conservation nuclei. For example, the Brazilian Somali were only collected in the conservation nucleus in Ceará State. No samples were collected to date for the Cariri breed, which is recognised by the Brazilian Ministry of Agriculture. Only two farms and one breed in the bank are from the northern region. Of the 27 states, there are samples in the gene bank of sheep from 13, so several states have no samples, requiring collection from herds outside the official system of conservation to make sure that studies using this germplasm realised are not biased. Significant genetic differences are seen above 332 km, which should guide future sampling efforts. Suggestions are given for improving the quantity, quality and diversity of samples in the gene bank.

Ovarian and follicular variables used to determine ewes with different FecGE genotypes.

Based on ovarian and follicular variables, there was determination of ewes with different FecGE genotypes. Based on the FecGE genotype, 65 Santa Inês ewes were assigned to three experimental groups: homozygous wild-type (n = 25; FecG+/+), mutant heterozygous (n = 27; FecG+/E) and mutant homozygous (n = 13; FecGE/E). The ewe's ovaries were weighed and measured, then the follicles (oocyte, nucleus and nucleolus) were histologically evaluated for morphometry and morphology. Morphologically normal follicles, in the primordial and transitional stages, explained 70.18% of the variability morphological characteristics between mutant and wild-type ewes. Conducting the morphometric evaluation resulted in a more precise determination of the genotype groups when there was assessment of the primordial and secondary follicular developmental stages. The diameter of the oocyte and the oocyte nucleus of the primordial follicles explained 36.76% of the variability in follicular morphology between ewes with the mutation and those with the wildtype group. Similarly, the core diameter of oocytes in secondary follicles explained 10.63% of the variability in follicular morphology among FecGE/E, FecG+/E and FecG+/+ ewes. Thus, morphologically normal follicles in the primordial and transitional stages of development are the variables that allow for a more precise differentiation of Santa Inês ewes with the FecGE mutation. These variables may be evaluated to make more efficient the adoption of biotechniques that when conducted there is utilisation of follicles in the initial developmental stages as a physiological basis for classifying whether specific follicles are useful when conducting the techniques.

Dimethylacetamide and trehalose for ram semen cryopreservation.

Eighteen semen samples from nine Santa Ines rams were cryopreserved in order to study the cryoprotective capacity of dimethylacetamide (DMA) at two concentrations (3% and 6%), and its interaction with trehalose (TRE, 100 mOsmol). A further objective of this study was to evaluate in vivo fertility of ram semen cryopreserved with dimethylacetamide. The control treatment was an extender medium with 6% glycerol (GLY). Five treatments were examined: 6% GLY, 3% DMA, 6% DMA, 3% DMA + TRE, and 6% DMA + TRE. After thawing, the kinetic sperm parameters were analyzed using a computerized system. Sperm viability was observed using a multiple parameter sperm staining with propidium iodide (for plasmatic membrane integrity), JC-1 (for mitochondrial membrane potential), and FITC-PSA (for acrosomal integrity). The isosmotic extender with GLY was the most effective medium for the maintenance of sperm characteristics, compared to extenders containing DMA as cryoprotectant. Regarding fertility, the extender medium with 3% DMA may be a safe alternative for sperm cryopreservation, and does not compromise the fertility rates. The addition of TRE decreased the kinetic sperm parameters; however, a positive effect on the integrity of the plasmatic and acrosomal membranes was observed.

The effects of gelatin supplementation prior to cooling on ram semen quality and fertility.

The physical and chemical characteristics of gelatin have been used to justify its inclusion in extenders to preserve the sperm quality and improve results of cervical artificial insemination with cooled semen. The objective of this study was to evaluate the effects of gelatin supplementation in cooling extender on the quality and fertility of ram semen stored at 5°C. Semen samples (n = 24) of Santa Inês rams (n = 6) were diluted in Glycine-Yolk-Milk extender without (control) or with 1.5% of gelatin. The samples were loaded into 0.25 mL straws, cooled to 5°C and stored vertically for 48 and 72 hours. Sample quality was evaluated using straw homogeneity tests based on pH, osmolality and the proportion of spermatozoa (PS) in both upper and lower segments of straws (US and LS), analyses of sperm motility, plasma and acrosomal membrane integrity, and by fertility after artificial insemination. Differences between the US and LS of straws were found for pH and PS (%). They were significant only in the control group at both times: pH - 5.96 vs. 5.71 at 48 h and 6.13 vs. 5.89 at 72 h; PS - 21.66 vs. 78.34 at 48 h and 20.87 vs. 79.13 at 72 h. Storage in gelatin had very little, to no effect on the sperm kinetics or on the sperm membrane integrity evaluations. The addition of gelatin to the extender did not affect the pregnancy rate which ranged from 4.4 to 26.1%. We conclude that gelatin is effective in maintaining the physical and chemical homogeneity of the semen samples. Further research is needed in order to optimize the use of gelatin supplementation and elucidate any potential benefits.

Effects of birth type and family on the variation of carcass and meat traits in Santa Ines sheep.

This study aimed to evaluate the effects of birth type and family on quantitative and qualitative meat traits in Santa Ines lambs and to do a descriptive study of variation inside of breed. A total of 50 carcass and meat traits were evaluated in up to 101 lambs slaughtered at 424 days of age. Random effect of family, the fixed effect of birth type (single or double) and year, and the covariates of dam's weight at weaning and age (in days) at slaughter were inserted in the model. This study shows that some carcass and meat traits in Santa Ines raised on pasture has large variability, specially for meat cut yields, several carcass non-components yields, and rib eye area, subcutaneous fat thickness, shear force, cooking losses, and b* color parameter. The birth type effect influenced (P < 0.05) rump width; reticulum, leg, heart and kidney yields; and the carcass pH at 24 h after slaughter. The family effect was significant (P < 0.05) for cold carcass weight; hot, cold and true carcass yields; external carcass and leg lengths; perimeter and width of the rump; kidney, liver and tail yields; and carcass pH at slaughter.

Use of cryotubes for the cryopreservation of tambaqui fish semen (Colossoma macropomum).

Tambaqui (Colossoma macropomum) is a freshwater fish of great importance to aquaculture in several South American countries. Recent studies have developed a protocol for semen cryopreservation in 0.25 and 0.5 mL straws; however, this technique has limitations for fingerling production at a large scale due to the high fecundity of tambaqui. The main objective of this study was to evaluate the feasibility of using cryotubes (1.6 and 4.5 mL) for tambaqui semen cryopreservation. Semen samples were diluted in freezing solution (5% glucose solution, 10% methylglycol, 5% egg yolk), stored in 1.6 and 4.5 mL cryotubes, frozen in liquid nitrogen vapor at -175°C and transferred to a cryogenic container at -196°C. The cryotubes were thawed in a water bath at 60°C for 70 or 90 s and the motility (total motility - TM; progressive motility - PM; curvilinear velocity - VCL; straight line velocity - VSL and average path velocity - VAP) and the viability of sperm were evaluated. There was no significant difference in sperm motility and viability post-thawing between 1.6 and 4.5m L cryotubes, except for TM (47% and 40%, respectively). Thawing for 90 s provided better results, being used in fertilization trials. Although the fertilization rate did not differ between the cryotubes (41-45%), it was significantly lower than that for fresh semen (74%). A strong positive correlation was observed between the sperm motility and fertilization rate (r=0.69-0.89). We conclude that 1.6 and 4.5 mL cryotubes have high potential for tambaqui semen cryopreservation when thawed for a minimum time of 90 s at 60°C.

Performance of the Santa Ines breed raised on pasture in semiarid tropical regions and factors that explain trait variation.

This study aimed to evaluate sex, the number of lambs per birth, and the family effects on production traits in the Santa Ines breed of sheep by estimating the least square means and coefficient of variance for those traits. A total of 484 lambs were evaluated for the following traits: weight at birth, at weaning, and at 240 days of age; weight gain during the pre-weaning and post-weaning periods; height, width, and length of different body regions; and rib eye area and fat thickness between the 12th and 13th ribs. We observed coefficients of variation higher than 10 % for several traits. Generally, males were larger than females (P < 0.05), while lambs from single and double births were larger than lambs from triple births (P < 0.05). Family effect was significant (P < 0.05) for most traits and explained the highest percentage of residual variance. The results showed good development of Santa Ines sheep, especially during the pre-weaning period but no in post-weaning. Our study also showed that there is an effect of sex, birth type, and family, which must be included in any statistical model for the estimation of least square means and residual variance in ANOVA.

Estimação de parâmetros genéticos de ovinos da raça Santa Inês utilizando modelos uni e bicaracterística / Estimation of genetic parameters Santa Inês Sheep breed using single and two - traits models

Objetivou-se nesse trabalho, estimar os parâmetros genéticos para características de crescimento em ovinos da raça Santa Inês através do Método da Máxima Verossimilhança Restrita (REML). Os componentes de (co)variâncias e os parâmetros genéticos foram estimados pelo Software MTDFREML (Multiple Trait Derivative-Free Restricted Maximum Likelihood). As características avaliadas em modelos uni e bicaracterística foram: peso ao nascimento (PN) e peso ao desmame (P90). Além dos efeitos fixos de sexo, grupo contemporâneo e tipo de parto, foram utilizados os seguintes efeitos aleatórios: efeito genético aditivo direto, efeito genético aditivo materno e efeito residual. As estimativas de herdabilidade aditiva direta para PN foram 0,20 e 0,21, para os modelos uni e bicaracterística, respectivamente. As estimativas de herdabilidade aditiva direta para P90 foram 0,04 e 0,07, para os modelos uni e bicaracterística, respectivamente. A correlação genética entre PN e P90 foi de 0,11, indicando que ambas as características devem ser trabalhadas simultaneamente.

The objective of this study is to estimate genetic parameters for growth traits in sheep Santa Ines breed by Restricted Maximum Likelihood (REML). The (co)variance components and genetic parameters were estimated by MTDFREML Software (Multiple Trait Derivative-Free Restricted Maximum Likelihood). The characteristics evaluated in single and two-trait models were: birth weight (BW) and weaning weight (WW). In addition to the fixed effects of sex, contemporary group and parity type, we used the following random effects: direct genetic effect, maternal additive genetic and residual effects. The direct additive heritability estimates for BW were 0.20 and 0.21 for single and two-trait models, respectively. Heritability estimates for direct additive WW were 0.04 and 0.07 for single and two-trait models, respectively. The genetic correlation between BW and WW was 0.11, indicating that both traits should be worked on simultaneously.

Hormonal induction and semen characteristics of tambaqui Colossoma macropomum.

In the hatchery-bred tambaqui Colossoma macropomum, spontaneous semen release does not occur, and hand-stripping produces reduced semen volume. The goal of this work is to evaluate the effects of hormonal induction with carp pituitary extract (CPE) on both qualitative (visual aspect, pH, motility, viability and morphological abnormalities) and quantitative (volume, concentration and number of spermatozoa per ejaculate) traits of tambaqui semen. Eleven males were treated with CPE (induced), and 11 were left untreated as a control (non-induced). All analysed parameters except motility and percentage of viable spermatozoa presented significant differences (p < 0.05) between the induced and non-induced treatments. CPE induction resulted in a 25-fold increase in semen volume and a 10-fold increase in the number of spermatozoa collected. However, both sperm concentration and the frequency of sperm with morphological abnormalities (commonly detached heads or bent tails) were significantly lower in CPE-induced fish. The hormonal induction of tambaqui males with CPE is efficient and positively influences some qualitative and quantitative properties of semen. Additionally, semen collection via gentle abdominal massage occurs more readily in CPE-induced fish.

Rapid serum agglutination and agar gel immunodiffusion tests associated to clinical signs in rams experimentally infected with Brucella ovis / Teste de soro aglutinação rápida e do teste de imunodifusão em gel de ágar associados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis

The purpose of this study was to evaluate the agar gel immunodiffusion and the rapid serum agglutination tests associated to clinical signs in rams experimentally infected with Brucella ovis. The serological profile during the 12 months of infection showed a large fluctuation of antibodies that favors the failure in the diagnostic. The evaluation of tests after the experimental infection allowed to suggest that none of the tests were able to detect the infection throughout the period of study. The study reinforces the importance of considering the clinical signs to support the diagnosis of Brucella ovis infection in rams.

O objetivo deste estudo foi avaliar o uso do teste de imunodifusão em gel de ágar e o teste sorológico de aglutinação rápida comparados aos sinais clínicos em carneiros infectados experimentalmente com Brucella ovis para o diagnóstico confirmatório da brucelose ovina. O perfil sorológico durante os 12 meses pós-infecção mostrou flutuação da resposta por anticorpos, que favorece a falha no diagnóstico. A avaliação dos testes indicou que nenhum dos testes foi capaz de detectar a infecção durante todo o período de estudo. O estudo ressalta a importância de considerar os sinais clínicos para apoiar o diagnóstico confirmatório da infecção por Brucella ovis em carneiros.

Genetic factors of sheep affecting gastrointestinal parasite infections in the Distrito Federal, Brazil.

Three sheep farms were used in the Distrito Federal, Central Brazil, to study the occurrence of parasites in the feces. A total of 1798 collections were taken over the period of a year. A total of 1205 were taken in Santa Inês breed (SI) in all three farms, 323 in Bergamasca (Berg), 54 in Ile de France, 49 in IlexSI, 103 in Morada Nova (MN) and 64 in TexelxSI, these last five groups being on a single farm. The animals were drenched soon after weaning and feces collected every 3 weeks to calculate fecal egg count (FEC), at least on two occasions on each animal. In some cases, blood was collected to determine packed cell volume (PCV) at fecal collection. Fixed effects included farm, breed/genetic group within farm, animal age (months), birth type (simple, twin) and sex. (Co)variance components were estimated for Santa Inês sheep using restricted maximum likelihood under an animal model. FECs were affected by month and farm showing that climate and management are important sources of variation for the parasites studied. While age and birth type of the lambs did not affect infection level, their genetic group was important, showing that breeding strategies can help control these parasites. Heritabilities for infection level in the sheep varied between 0.09 for Strongyloides and 0.31 for Moniezia expansa. Genetic selection strategies for sheep aimed at reducing these infections should result in more resistant animals.