Genetic parameters for reproduction and growth traits in Boer goats in Brazil

Estimation of crossbreeding and genetic parameters for reproductive traits of Boer x Central Highland goats in Ethiopia

Additive genetic and non-additive parameters for reproductive traits of Boer x Central Highland goats were estimated. Pedigree and performance records comprised of Central Highland and their crosses with Boer goats were collected from 2009 to 2018 in the Sirinka Agricultural Research Center sheep and goat breeding station. Least-squares means for genotypes were obtained using a general linear model procedure in SAS. To estimate crossbreeding parameters, breed additive, heterotic, and recombination effects were fitted as fixed covariates instead of genotypes. Variance, heritability, and repeatability estimates were estimated through the AI-REML algorithm using WOMBAT software. Genotype did not significantly (P>0.05) influence most of the reproductive traits studied except for gestation length. The additive effect for litter size at birth (LSB), total litter birth weight (LBW), total litter weaning weight (LWW), litter size at weaning (LSW), and gestation length (GL) was estimated to be -0.004 kid, 0.08 kg, -3.18 kg, -0.54 kid, and 3.69 days, respectively. The contribution of heterosis to LSB, LWW, and GL of crossbred goats was negative, while the estimates for LBW and LSW were positive. However, Boer goats' heterosis effect and direct additive contribution to reproductive traits were insignificant (P>0.05) except for LSW. The recombination effect was negligible and not significant (P>0.05) for all traits examined. The direct heritability estimate for LSB, LWB, LWW, LSW, and GL were 0.050, 0.098, 0.086, 0.018, and 0.00, respectively. The repeatability estimates for LSB, LWB, LWW, LSW, and GL were 0.149, 0.116, 0.099, 0.086, and 0.061, respectively. The result indicates that improvement in reproductive traits would not be expected by crossing Boer with Central Highland goats. In addition, heritability estimates indicate that the improvement of reproductive traits through selection will be small, and the repeatability estimates indicate that multiple records have to be used to make a decision of culling or selection.

Estimates of Genetic Parameters for Direct and Maternal Effects on Pre-Weaning Growth Traits in Turkish Saanen Kids

Data on 4487 Turkish Saanen kids from 176 bucks and 1318 dam-goats, obtained from the Turkish Saanen goats in the Izmir region and collected between 2018 and 2019, were analyzed to examine the effect of genetic and non-genetic factors on growth traits. The average birth weight of the kids was determined as 3.33 ± 0.68 kg, the average W60 was 13.06 ± 2.94 kg, the average WW was 18.38 ± 4.14 kg, and the average PreWDG until weaning was 0.17 ± 0.04 g. Model 1, which does not account for the maternal effect, and Model 2, which includes the maternal effect, were used in the estimation of genetic parameters. The heritability estimates of BW, W60, WW, and PreWDG ranged from 0.05 to 0.59 in both models. It is recommended to consider the maternal effect as well as the environmental factors in the selection program for the best early breeder selection of kids growing alongside their mothers until the weaning period.

Heritability and environmental influence on pre-weaning traits in Kilis goats

Birth and weaning weights, average daily weight gain, and Kleiber ratio are important indicator traits in selection decision. The phenotypic expression of these traits is determined by the genetic background, environmental effects, and their interactions. The objective of this study was to estimate genetic parameters regarding birth (BW) and weaning weights (WW) and average daily weight gain (ADWG), Kleiber ratio (KR), and obtain the effects of sex, birth type, herd, and year. The data consisted of 2274 Kilis goats with pedigree information obtained from 53 bucks and 774 does in 4 generations. The restricted maximum likelihood (REML) procedure was conducted with an animal linear mixed model. Sex, birth type, herd, and year were found to be statistically significant (p value < 0.001) for all traits. Moderate direct heritabilities (h_a²) for BW, WW, ADW, and KR were found to be as 0.18 ± 0.03, 0.50 ± 0.04, 0.47 ± 0.04, and 0.37 ± 0.05, respectively. The proportion of maternal permanent environmental effect (c²) to the total phenotypic variance (σ²_p) was estimated as 0.00 ± 0.00, 0.12 ± 0.02, 0.11 ± 0.02, and 0.18 ± 0.03 for BW, WW, ADWG, and KR, respectively. The genetic, phenotypic, and environmental correlations between the pre-weaning growth traits were found to be ranging from - 0.02 to 0.99. Thus, our study suggests moderate heritabilities and positive and relatively high genetic correlations among the observed pre-weaning growth traits. These results have implications in terms of providing rapid genetic progress for these traits in breeding programs of Kilis goats.

Study of genetic parameters for pre-weaning growth traits in inner Mongolia white Arbas cashmere goats

Inner Mongolia Arbas white cashmere goats is a dual-purpose breed for producing cashmere and meat. In recent years, its meat has become more and more popular among consumers because of rich nutrients and delicious flavor. Therefore, it is particularly important to study the genetic and non-genetic factors affecting the early growth traits and estimate variance components of pre-weaning growth traits of Inner Mongolia Albas white cashmere goats. A total of 37487 kidding records such as birth weight (BWT), weaning weight (WWT), average daily gain from birth to weaning (ADG) and Kleiber ratio (KR) from 343 sires and 7296 dams were used in this study. The most appropriate model was chosen on the basis of likelihood ratio test by fitting six models which excluding or including maternal genetic, maternal permanent environmental effects. The parameters were estimated under the most appropriate model using AIREML method by WOMBAT software. With the best model (Model 6), heritability estimates were 0.0435, 0.0911, 0.0932 and 0.2339 for BWT, WWT, ADG and KR traits, respectively. Maternal heritability estimates were 0.0143, 0.0246, 0.0220 and 0.0186 for BWT, WWT, ADG, and KR traits respectively. The correlation between different traits was estimated with the most suitable model by using bivariate analysis method. The direct additive genetic correlation among the traits ranged from -0.026 (BWT~KR) to 0.772 (ADG~KR). The maternal permanent environment correlation is between -0.289 (BWT-KR) ~0.900 (WWT-ADG). Results indicated that maternal effects and direct-maternal genetic covariance should be considered in any program aimed at improving pre-weaning growth traits to have an accurate genetic evaluation. In addition, positive and medium to high genetic correlations generally exist among WWT, ADG and KR due to the existence of genetic variation for early growth traits. The results showed that the genetic progress of these traits could be slowly through selection except for KR.

Assessment of Genetic Diversity and Conservation in South African Indigenous Goat Ecotypes: A Review

Goats were amongst the first livestock to be domesticated more than 10,000 years ago for their meat, milk, skin, and fiber. They were introduced to Southern Africa by migrating nations from Central Africa to the south. Due to local adaptation to the different agro-ecological zones and selection, indigenous goats are identified as ecotypes within the indigenous veld goat breed. Their ability to thrive in a resource-limited production system and in challenging environmental conditions makes them valuable animal resources for small-scale and emerging farmers. They play important roles in household agriculture and cultural activities as well as in poverty alleviation. Studies have described the phenotypic and genetic variations in indigenous goats, targeting the major goat-producing regions and the breeds of South Africa. In turn, information is restricted to certain breeds and regions, and the experimental design is often not adequate to inform the conservation status and priorities in changing environments. Advances in genomics technologies have availed more opportunities for the assessment of the biodiversity, demographic histories, and detection regions associated with local adaptation. These technologies are essential for breeding and conservation strategies for sustainable production for food security. This review focuses on the status of indigenous goats in South Africa and the application of genomics technologies for characterization, with emphasis on prioritization for conservation and sustainable utilization.

Genetic analysis of sexual dimorphism in growth of Jamunapari goats of India

A genetic study of sexual size dimorphism (SSD) in Jamunapari goats was carried out to identify differences between sexes in genetic control of body weight at birth and at 3 (weaning), 6, 9 and 12 months of age. A total of 6,687 kids out of 264 sires and 1,704 dams were used in the study. Estimates of SSD were derived from male:female body weight ratios. Males were 9.9, 6.8, 9.3, 13.7 and 16.8% heavier than females at birth and at 3, 6, 9 and 12 months of age, respectively, demonstrating modest SSD. Phenotypic standard deviations were larger for male kids and tended to be proportional to body weight means. However, males also had somewhat greater phenotypic coefficients of variation and total resemblance among relatives. Additive direct genetic correlations between body weights of males and females exceeded 0.96 at birth and weaning. Corresponding additive maternal correlations exceeded 0.99. Additive direct correlations between sexes were somewhat less than unity for postweaning weights but exceeded 0.80 in multi-trait models. Our results indicated that body weights could be treated as the same trait in males and females, but the use of different phenotypic variances for the two sexes would improve accuracies of breeding value predictions. High genetic correlations between body weights in males and females suggest limited opportunity to use sex-specific selection to create or modify SSD or create divergent body weight phenotypes between sexes.

Estimation of genetic parameters for early reproduction traits in Beetal goat

The evaluation of early reproduction traits in Beetal goat was performed for possible effects of genetic and non-genetic factors on litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW) and age at first kidding (AFK). The data records consisted of information of pedigree and targeted traits pertained to 223 does born to 25 sires and 122 dams between the years 2004 to 2019. A general linear model was used for assessment of non-genetic factors such as period of birth, type of birth and dam's weight at kidding on studied traits. Genetic evaluation of targeted traits was done to estimate variance components and genetic parameters under dyadic mixed modelling. The estimates of least-square means for LSB, LSW, LWB, LWW and AFK were observed as 1.27 ± 0.03, 1.25 ± 0.03, 3.24 ± 0.07 kg, 13.08 ± 0.30 kg and 27.56 ± 0.58 months, respectively. Only the period of birth showed significant (P < 0.05) effects for targeted traits in this study. The estimates of direct heritability for LSB, LSW, LWB, LWW and AFK were low in magnitude as 0.08, 0.03, 0.10, 0.03 and 0.06, respectively. The moderate to high genetic and phenotypic correlations among litter traits indicate simultaneous improvement for these traits. It was concluded that low ranged direct heritability estimates for targeted traits indicated modest scope for genetic improvement of reproductive efficiency in Beetal goat through selection and, therefore, adoption of improved managerial practices is necessary to improve reproductive efficiency of Beetal goat.

Reproductive performance and milk production of Central Highland and Boer x Central Highland goats

This study was conducted to evaluate the reproductive performance and milk production potential of Central Highland and Boer x Central Highland goats under semi-intensive management. Data were collected from 2009 till 2018 in the Sirinka goat breeding station. A general linear model procedure of the Statistical Analysis System (SAS) was used to analyze the data. The overall least-squares mean litter size at birth (LSB), litter size at weaning (LSW), total litter weight at birth, total litter weight at weaning and gestation length (GL) were 1.6 ± 0.02 kids, 1.4 ± 0.02 kids, 3.9 ± 0.05 kg, 13.6 ± 0.35 kg and 148.0 ± 0.33 days, respectively. The LSB, LSW and GL did not differ between Central Highland and their F1 and F2 crossbred dams. However, F2 dams produce the lightest kid at birth and weaning. Besides, birth type, season, year and parity were important sources of variation for most of the reproductive traits. The least-squares mean for daily milk yield (DMY), lactation milk yield (LMY) and lactation length (LL) were 0.34 ± 0.02 kg, 39.16 ± 3.00 kg and 104.2 ± 4.45 days, respectively. The DMY and LMY of Boer x Central Highland goats were higher than pure Central Highland goats by 46.4% and 27.2%, respectively. However, the LL for both genotypes was found to be similar (P > 0.05). Dams kidding during the short rainy season produce more milk than kidding during dry and main rainy seasons. Boer x Central Highland goats produce more milk than pure Central Highland goats. However, using Boer crossbred dams did not reveal any advantage over the base Central Highland dams in terms of reproductive performance. Therefore, using Central Highland goat as a dam line, improving the management and integration of crossbreeding with selection could be an ideal option to improve the overall productivity of goats.

Variation in autosomal and sex-linked genetic effects for growth traits in Markhoz goat using multivariate animal models

The present study was conducted to estimate autosomal and sex-linked genetic parameters by restricted maximum likelihood method using four different multivariate models for growth traits in Markhoz goat. Data were collected over a period of 23 years (1992-2014) from the breeding station of Markhoz goat. The studied growth traits were birth weight (BW), weaning weight (WW), 6-month weight (6WT), 9-month weight (9WT), and 12-month weight (12WT). The best model was determined by Akaike's information criterion. Based on the best model, direct autosomal heritabilities of 0.18, 0.10, 0.12, 0.22, and 0.24 were obtained for BW, WW, 6WT, 9WT, and 12WT, respectively. On the other hand, estimates of direct sex-linked heritability for BW, WW, 6WT, 9WT, and 12WT were 0.02, 0.01, 0.002, 0.03, and 0.04, respectively. The maternal permanent environmental component was remarkable for growth traits. Direct autosomal additive genetic correlations among the traits were positive and varied from 0.11 between BW and 9WT to 0.95 between BW and WW. The positive correlations were also estimated for direct sex-linked additive genetic effect except between BW-6WT (- 0.07) and WW-6WT (-0.19). The result of this study indicated that sex-linked chromosome effect had more considerable influence at post-weaning traits.

Estimation of additive and non-additive genetic variance component for growth traits in Adani goats

Non-additive genetic effects are important to increase the accuracy of estimating genetic parameters for growth traits. The aim of this study was to estimate genetic parameters and variance components, specially dominance and epistasis genetic effects, for growth traits (birth weight (BW), weaning weight (WW), 3 (W3), 6 (W6), 9 (W9), and 12 (W12) month weight) in Adani goats. Analyses were carried out using Bayesian method via Gibbs sampler animal model by fitting of 18 different models. All fixed effects (sex, type of birth, age of dam, and year) showed significant effects on BW, WW, W3, and W6, whereas the type of birth and age of dam were not significant on W9 and W12. With the best model, direct heritability estimates were 0.347, 0.178, 0.158, 0.359, 0.278, and 0.281 for BW, WW, W3, W6, W9, and W12 traits, respectively. Maternal permanent environmental effect was significant for BW and WW, but maternal genetic effect was significant only for W3. Dominance and epitasis effects were significant almost for all traits and as a proportion of phenotypic variance were ranged from 0.115 to 0.258 and 0.107 to 0.218, respectively. The range of accuracy of breeding values estimated for growth traits with appropriate evaluation models was from 0.521 to 0.652, 0.616 to 0.694, and 0.548 to 0.684 for the all animals, 10% of the best males and 50% of the best females, respectively. When dominance and epistasis effects added to models, the error variance was reduced and the accuracy of estimated breeding values increased. The accuracy of the best model showed a significant difference with the accuracy of other models (p < 0.01). The result of the present study suggests that non-additive genetic effects should be in genetic evaluation models for goat growth traits because of its effect on accuracy of estimated breeding values.

Genetic and phenotypic aspects of early reproductive performance in Raeini Cashmere goats

This study used pedigree information and data collected from 1979 to 2012 at the Raeini Cashmere goat breeding station, located in Baft City in Kerman Province in southeastern Iran. Genetic and phenotypic parameters for early reproductive traits of breeding does, including total numbers of kids born at first kidding (LSB1), total numbers of kids weaned at first kidding (LSW1), total birth weight of all kids born at first kidding (LWB1), total weaning weight of all kids weaned at first kidding (LWW1), and age at first kidding (AFK), were estimated using a Bayesian approach via Gibbs sampling. Posterior means for heritability estimates of LSB1, LSW1, LWB1, LWW1, and AFK were statistically significant, with values of 0.12, 0.23, 0.17, 0.15, and 0.46, respectively. Low-to-moderate additive genetic variation was present for the studied reproductive traits. Estimated genetic correlations among LSB1, LSW1, LWB1, and LWW1 were statistically significant and ranged from 0.12 between LWB1 and LWW1 to 0.72 between LSB1 and LSW1. Corresponding phenotypic correlation estimates were also statistically significant and ranged from 0.04 between LWB1 and LWW1 to 0.55 between LSB1 and LSW1. Posterior means of genetic and phenotypic correlations between AFK and other studied traits were statistically significant only for LSB1 and LWB1. For LSB1, LSW1, LWB1, and LWW1, we conclude that genetic and phenotypic improvement in any of these traits in Raeini Cashmere does would favorably influence all of the other traits. However, does that first kidded at younger ages have smaller litters at birth and lower litter birth weights at their first parity.

Influence of crossbreeding on meat goat doe fitness when comparing Boer F1 with base breeds in the Southeastern United States

Understanding fitness level among various breeds is essential for sustainable meat goat production. Research on the relative fitness of Boer F1 does and straightbred base breed has been limited. Meat goat does of various genotypes (Boer, Kiko, Spanish, Boer × Kiko reciprocal F1 crosses, and Boer × Spanish reciprocal F1 crosses) were studied to evaluate breed effects on doe fitness traits and the expression of heterosis over 7 production years. The herd was semi-intensively managed under humid subtropical pasture. Doe age affected (P < 0.05) various traits. Boer × Kiko does were heavier (P < 0.05) than Boer does at fall breeding, but Boer × Spanish does did not differ (P > 0.05) from Boer does for breeding weight. The body weights of Boer × Spanish and Boer × Kiko crosses did not differ (P > 0.05) from the weights of their respective Kiko and Spanish base cohorts at breeding, kidding, or weaning. Boer does had lower (P < 0.05) kidding rate (KR) and weaning rate (WR) than the other breeds and crosses. Boer × Kiko and Kiko were similar for KR and WR. Boer × Spanish and Spanish were also similar for KR and WR. However, the combined group of Boer F1 does had lower (P < 0.01) KR and WR than the combined purebred biotype group of Kiko and Spanish does. Boer does weaned smaller (P < 0.05) litter sizes per doe exposed compared with Kiko, Spanish, Boer × Kiko, and Boer × Spanish does with the latter four doe breedtypes not differing from each other. The combined Boer F1 doe group weaned smaller (P < 0.05) litter sizes per doe exposed than the combined purebred group of Kiko and Spanish does. Boer × Kiko dams had higher (P < 0.05) fecal egg counts at parturition than Kiko dams. Significant heterosis was observed for reproductive traits within each of the 2-breed diallels. Boer F1 does exhibited reproductive output similar to or lower than Kiko and Spanish straightbred does and higher than Boer straightbred does.