Derivative-free Restricted Maximum Likelihood Research Articles

Genetic assessment of productive and reproductive traits in Friesian, native, and crossbred cattle in Egypt

This study utilized a dataset comprising 3023 lactation records for Friesian cows, 596 records for Native cows (Baladi), and 1189 records for Crossbred cows spanning from 1994 to 2015. The objective was to estimate and assess genetic and phenotypic parameters and breeding values for 305-day milk yield (305-DMY), lactation period (LP), calving interval (CI), and days open (DO) within the Egyptian dairy context. The motivation for this research stemmed from the need to understand the genetic potential of different cattle genotypes in Egypt and identify opportunities for enhancing dairy production. Data were analyzed using the linear mixed model least squares and maximum likelihood (LSMLMW) and multiple-trait derivative-free restricted maximum likelihood (MTDFREML) programs. The analytical model included fixed effects such as season and year of calving, parity, and genotype groups, while random effects included animal and error. Unadjusted means for 305-DMY, LP, CI, and DO were calculated for each genotype group. Genotype groups significantly impacted all studied traits. Heritability estimates varied across genotype groups, with higher estimates observed in Crossbred (0.32, 0.26, 0.25, 0.23) and Native cows (0.26, 0.28, 0.28) compared to Friesian cows (0.24, 0.22, 0.16, 0.17) for productive and reproductive traits, respectively. Genetic correlations among traits ranged from 0.10 to 0.86 for the three genotype groups, while corresponding phenotypic correlations were generally small to moderate and positive. Regarding breeding values, the accuracy estimates suggested that both sires and cows could contribute to genetic improvement. This indicates the potential for enhancing dairy production through selective breeding strategies.

Recent Advances in Sire Evaluation Methods: A Review

This review deals with the various traditional and recent methods of sire evaluation. A sire evaluation is a method of prediction of sire’s next-generation produced by breeding with specified females and creating their records in a specific environment. Breeding worth of progeny tested sires are obtained through sire index method that assigns ranking to each sire based on their genetic merit. Numerous sire indices are broadly classified in two type’s viz., indices which are purely meant for ranking purposes and those which, besides, provide an estimate of the breeding worth of each sire. Sires can be evaluated in single or multiple herds. The statistical equations represent sire evaluation as linear or non-linear methods. Numerous methods can be incorporated as the advances are made in sire evaluation based on data structures, breeding approaches and selection methods. There are various approaches of sire evaluation such as Least Squares Method (LSM), Simple Regressed Least Squares (SRLS), Best Linear Unbiased Prediction (BLUP) and Derivative-Free Restricted Maximum Likelihood (DFREML) for single as well as multiple trait models which can be used to derive genetic worth of an individual. An efficient method of sire evaluation shows minimum within sire variance or error variance.

Partitioning variation in measurements of beef carcass traits using ultrasound.

Ultrasound technology provides cattle breeders with a quick, noninvasive, and inexpensive way to measure carcass data on live animals. Ultrasound data are used as indicator traits in cattle genetic evaluations for economically relevant carcass traits. Ultrasound cattle genetic evaluations assume homogeneous additive genetic and residual variance. Thus, the objective was to partition phenotypic variance in ultrasound carcass measurements into components for additive genetic effects, technicians, contemporary groups within technicians, and residual and to examine the homogeneity of these variances among image interpretation laboratories. Records of longissimus muscle area (LMA), percentage of intramuscular fat (IMF), and subcutaneous fat depth (SFD), measured using ultrasound, were provided by the American Angus Association (n = 65,967), American Hereford Association (n = 43,182), and American Simmental Association (n = 48,298). The data also included contemporary group, technician, imaging lab, and a three-generation pedigree for each animal. Variance components for ultrasound carcass measurements were first estimated with univariate animal models for each breed and imaging laboratory using derivative-free restricted maximum likelihood. Then, treating data from each imaging laboratory as separate traits, genetic correlations between laboratories for LMA, percentage of IMF, and subcutaneous fat were estimated with trivariate animal models. The technician explained 12–27%, 5–23%, and 4–26% of the variance for IMF, SFD, and LMA, respectively, across all three breeds. Variance due to technician was often greater than variance due to additive genetic effects but almost always less than that explained by the contemporary group. Within breeds, estimates of additive genetic variance for LMA, SFD, and IMF differed (range divided by mean) among laboratories by 4.5%, 21.5%, and 39.4 % (Angus); 31.6%, 15.0%, and 49.1% (Hereford); and 19.9%, 46.6%, and 55.3% (Simmental), respectively. Likewise, estimates of residual variance for LMA, SFD, and IMF differed among laboratories by 43.4%, 22.9%, and 43.3% (Angus); 24.9%, 15.2%, and 79.2% (Hereford); and 26.4%, 32.5%, and 46.2% (Simmental), respectively. Genetic correlations between labs across breeds ranged from 0.79 to 0.95 for IMF, 0.26 to 0.94 for SFD, and 0.78 to 0.98 for LMA. The impact of the observed heterogeneity of variance between labs on genetic evaluation requires further study.

Brazilian Sport Horse: genetic parameters for approval of Brasileiro de Hipismo stallions.

The aim of this study was to evaluate genetic parameters for subjective scores given at the Brazilian Sport Horse (BSH) Stallion Approval by estimating heritability (h2) for morphological, gait, and jumping traits and genetic correlations (γg) among the functional ones and by verifying selection feasibility. The analysis included 1179 complete evaluations from 294 horses, by 4.26 ± 0.96 judges. Each trait was evaluated using mixed models in SAS® v9.2, considering the individual as a random effect. Variance components and genetic parameters were obtained by single and two-trait animal models in a derivative-free restricted maximum likelihood analysis. Since many jumping traits were not described in Breed Regulation, mixed model results were used to enlighten the criteria adopted in the assignment of scores. Balanced bodies and conformations that favor collection were preferred by judges and presented moderate heritabilities. Additive variation was found for most jumping traits, with heritability equal to 0.74 (se = 0.04) for overall jump, and estimates for the separate aspects of the jump movement ranging from near null to 0.43 (se = 0.07) for temperament. Morphological scores had little effect over gait and jump scores while trot may be indicative of some additive value for jump distance and canter for hind limb mechanics. Conformation evaluations of separate body regions presented heritability estimates similar to previous studies and may provide more informative breeding values.

Heritabilities for the puppy weight at birth in Labrador retrievers

BackgroundWeight at birth is an important predictor of neonatal mortality and morbidity in dogs. In addition, the birthweight of the puppies in a litter influences the decision to perform a cesarean section. The goal of the present study was to estimate heritabilities for the puppy birth weight in Labrador retrievers.ResultsOf the 1138 Labrador retriever litters whelped at the Guiding Eye for the Blind between September 2001 and February 2018, 1013 were included in the analyses after data editing. Puppy weight at birth was the target trait, measured on a continuous scale in pounds, and converted to grams. Linear mixed models were used to identify factors influencing puppy weight at birth. The analyses showed that the sex of the puppy, litter size, length of gestation, adult weight of the dam, parity, year of birth and inbreeding coefficient of the puppies and dams contributed to the variance of the puppy birth weight. Dam and litter effects were included as random effects. A multiple trait derivative free restricted maximum likelihood approach was used to estimate variance components and genetic parameters with two animal models, one without covariates (Model 1) and one with covariates (Model 2). Sex of the puppy and litter size had moderate effects, whereas gestation length, adult weight of the dam, parity, year of birth and inbreeding coefficients of the dam and the puppies had minor effects. Estimates for Model 1 and Model 2 were 0.21 and 0.17 for the direct heritabilities, 0.22 and 0.22 for the maternal additive genetic heritabilities, 0.07 and 0.07 for the maternal permanent environmental proportions, and 0.14 and 0.08 for the environmental proportion of the litter.ConclusionsIn order to estimate reliable breeding values for puppy weight at birth, sex of puppy, litter size, length of gestation and the adult weight of the dam should be included. Estimates could benefit from weighing the dams prior to each mating.

Alternative models for genetic evaluation of feed intake by Afrikaner cattle

The objectives of this study were to evaluate statistical models of potential utility for genetic evaluation of feed intake and to estimate the (co)variance components and genetic parameters that would be necessary for their use in a national cattle evaluation scheme. Data were from Afrikaner bulls that were tested between 1974 and 2016 in Phases C (n = 1 250) and D (n = 11 083) of the National Beef Recording and Improvement Scheme. Statistical analyses in which the number of traits varied and contemporary group effects were considered either random or fixed were conducted using multiple-trait derivative-free restricted maximum likelihood. Contemporary group effects were important. When they were considered random, the estimated phenotypic variance of feed intake increased and its heritability reduced from approximately 0.43 ± 0.09 to approximately 0.30 ± 0.06. Use of average daily gain, recorded either concurrently with the feed intake measure (ADGC) or from related bulls reared on-farm (ADGD), had relatively little effect on estimated heritability of feed intake. Thus, considering contemporary group effects random consistently increased the accuracy of the estimated breeding values. Relatively small genetic correlations between ADGC and ADGD complicated the ultimate application of data recorded in Phase C and the use of data recorded in Phase D in decoupling the phenotypes for feed intake and growth in an evaluation of feed efficiency. Some modification of testing procedures may be necessary to facilitate this application of the results.Keywords: accuracy, contemporary group, genetic parameters, performance testing

Genetic parameters for loin eye area and other body traits of an important Neotropical aquaculture species,Colossoma macropomum(Cuvier, 1818)

Estimating components of variance and genetic parameters of economically relevant traits is the first step towards planning a breeding program for aquaculture species. This study estimated the (co)variance components for growth rate and other body traits and then determined a multiple regression equation to assess the loin eye area (LEA) from morphometric traits of the Neotropical aquaculture species Colossoma macropomum. Estimation of variance components was performed using derivative-free restricted maximum likelihood estimation using the MTDFREML package. Six predictive variables were tested to estimate the coefficient of regression equation and to select the most suitable model for predicting LEA. The estimated genetic parameter for body weight showed moderate-to-high heritability estimates of 0.26 (0.01) and 0.49 (0.01) at 221 and 623 days respectively. The genetic correlation (rg) estimates between body size measurements were positive and ranged from low to high at both ages. The heritability for LEA in this assessment was 0.39 (0.03). The genetic and phenotypic correlations between LEA and the other body measurements ranged from 0.16 to 0.94 and 0.75 and 0.90 respectively. The outcomes of this study can contribute to the development of a genetics-based breeding program that will improve (tambaqui) productivity and carcass quality.

Estimation of Genetic Parameters for Peak Yield, Yield and Persistency Traits in Murciano-Granadina Goats Using Multi-Traits Models.

Simple SummaryThe Murciano-Granadina goat is a local breed of importance, not only for the economic and social impact of the breeders but also for its conservation. Estimates of the genetic parameters of peak and persistency traits (not commonly used in breeding schemes) using multivariate models is a feasible tool in early lactation (could genetically modify lactation curves) for improving sustainable production in dairy goats, specifically when more data are available. The genetic variability for the parameters of the lactation curve (peak yield, yield and persistency studied traits) is low. The heritability was low to intermediate in all the traits, being between 0.08 for persistency and 0.17 for yield. The genetic correlations were high for peak yield and yield (0.94), indicating that the selection for both peak production and persistence is feasible, with no detrimental response in either. Murciano-Granadina should be a guide dairy goat, and the result could provide a general strategy applicable to other local breeds.This paper studies parameters of a lactation curve such as peak yield (PY) and persistency (P), which do not conform to the usual selection criteria in the Murciano-Granadina (MG) breed, but are considered to be an alternative to benefit animal welfare without reducing production. Using 315,663 production records (of 122,883 animals) over a period of 24 years (1990–2014), genetic parameters were estimated with uni-, bi- and multivariate analysis using multiple trait derivative free restricted maximum likelihood (MTDFREML). The heritability (h2)/repeatability (re) of PY, yield (Y) and P was estimated as 0.13/0.19, 0.16/0.25 and 0.08/0.09 with the uni-trait and h2 of bi- and multi-traits analysis ranging from 0.16 to 0.17 of Y, while that of PY and Y remained constant. Genetic correlations were high between PY–Y (0.94 ± 0.011) but low between PY–P (–0.16 ± 0.054 to –0.17 ± 0.054) and between Y–P (–0.06 ± 0.058 to –0.05 ± 0.058). Estimates of h2/re were low to intermediate. The selection for Y–PY or both can be implemented given the genetic correlation between these traits. PY–P and Y–P showed low to negligible correlation values indicating that if these traits are implemented in the early stages of evaluation, they would not be to the detriment of PY–Y. The combination of estimated breeding values (EBVs) for all traits would be a good criterion for selection.

Estimation of genetic and environmental parameters for milk traits in jersey cows

The aim of this study was to estimate the genetic parameters and environmental factors for test day milk yield (TDMY), lactation milk yield (LMY), 305-day milk yield (305-DMY), milk fat percentage (FP) and milk protein percentage (PP) of Jersey cows raised on Karaköy Agricultural State Farm in Samsun province of Turkey. The data were obtained from 279 milk yield records of 170 heads cows calved from 2011 to 2013 years. Parity, calving season and calving year were considered as fixed effects. Heritability, additive genetic variance and phenotypic variance were estimated by multiple trait derivative free restricted maximum likelihood (MTDFREML) with the animal model. Variance analysis results showed that except for FP, the effects of parity and calving year on TDMY, LMY, 305-DMY and PP were significantly important (P<0.05). However, calving season did not affect TDMY, LMY, 305-DMY, FP and PP (P>0.05). Heritability estimates for TDMY, LMY, 305-DMY, FP and PP were 0.38, 0.30, 0.28, 0.19, and 0.36, respectively. Repeatability for TDMY, LMY, 305-DMY, FP and PP were ranged from 0.35 to 0.45. The results indicate that these traits can be used as a selection criteria in genetic improvement of Jersey cattle this herd.

Heritability and variance components estimates for growth traits in Saudi Ardi goat and Damascus goat and their crosses

Objective: To study the genetic and non-genetic factors and their interactions affecting growth rate and body weights at birth, weaning and at 6 months of age in Saudi Ardi, Damascus goats and their crosses. Methods: Crossbreeding program between Saudi Ardi(A) goats with Damascus(D) was carried out to improve the meat productivity of Ardi goats through crossbreeding. The pedigree records of the body weights were obtained from 754 kids (397 males and 357 females) produced from 46 Sires and 279 Dams. Birth weight, weaning weigh and 6 months weight as well as average daily gain during different growth stages from birth to weaning (D1), weaning to 6 months (D2) and from birth to 6 months of age (D3) were recorded during winter/autumn and summer/spring. Data were classified according to breed, generation, sex, season, year, and type of birth. Data were analyzed using GLM procedure for the least-squares means of the fixed factors. Heritability and genetic parameters were estimated with derivative-free restricted maximum likelihood procedures using the MTDFREML program. Results: The percentages of variations were moderate for body weights and high for daily gains. Genetic groups had a highly significant (P<0.01) effect on the body weights traits. Damascus goats had higher (P<0.01) birth and weaning weights, but ½D½A group kids had a higher (P<0.01) body weight at 6 months. The genetic groups had a significant effects on the daily weight gains for D1 (P<0.01) and D3 (P<0.05) periods, whereas, it had no effects on D2 period. The fixed effects of sex, season, year and type of birth were significant differences for body weights. Male kids were heavier (P<0.01) than females for different growth stages. Body weights and daily gains during winter/autumn were significantly higher (P<0.01) than summer/ spring. Kids born and raised as singles were significantly (P<0.01) heavier than those were born as twins or triplets. The genetic and phenotypic correlations between birth and weaning weights were positive for both Damascus and Ardi goats. Conclusions: Genetic program for Ardi goats through upgrading with Damascus is possible to improve meat production.

Genetic parameters of growth traits in Nellore cattle

This study evaluated non-genetic factors and calculated heritability estimates of direct and maternal effects for growth traits in Nellore cattle raised in southern Brazil. Performance records of 4170, 1538, 3139, 1830, and 1151 calves born from 2005 to 2011 were analyzed for birth weight (BW), adjusted120-day weight (W120), adjusted 205-day weight (W205), adjusted365-day weight (W365), and adjusted 550-day weight (W550), respectively. The components of (co)variance used to calculate heritability estimates were determined by Derivative-Free Restricted Maximum Likelihood using the MTDFREML software. Contemporary groups were included in the model as fixed effects, and direct and maternal effects, permanent environmental effects, and residual errors were included as random effects. Phenotypic correlations were estimated using the PROC CORR procedure from SAS. Overall means for BW, W120, W205, W365, and W550 were 38, 138, 201, 270, and 376 kg, respectively. Heritability estimates for direct and maternal effects were 0.17 ± 0.04 and 0.11 ± 0.03 (BW), 0.14 ± 0.03 and 0.03 ± 0.04 (W120), and 0.17 ± 0.04 and 0.09 ± 0.03 (W205). Genetic, phenotypic, and environmental correlations were 0.79, 0.44, and 0.32 for BW and W120, 0.79, 0.39, and 0.26 for BW and W205, and 0.96, 0.74, and 0.75 for W120 and W205. The results indicate that selection for pre-weaning weight would be more efficient using W205, and genetic correlation coefficients indicate that selection at any age should produce a positively correlated response at older ages. Genetic, phenotypic, and environmental correlation coefficients between W365 and W550 were 0.99, 0.75, and 0.76, respectively. Selection for adjusted 550-day weight should produce the greatest genetic gains. Genetic correlation coefficients between weight traits indicate that selection for weight at older ages, which could help reduce the number of weighings and increase accuracy of selection at younger ages, produces gains at older ages.

CLIMATE SPATIALIZATION AND GENOTYPE-ENVIRONMENT INTERACTION EFFECTS ON WEANING WEIGHTS OF NELLORE CATTLE IN EXTENSIVE SYSTEMS IN TROPICAL REGIONS OF BRAZIL

Abstract Depending on the environmental differences among the regions, the phenotypic expression in beef cattle may significantly vary between the progenies of the same sire, and this is an important rule to identify the best animal. Thus, this study was carried out to spatialize environmental factors that may help to compare and discriminate the states of Maranhão, Pará, and Tocantins and also to check for genotype x environment interaction (G x E interaction) in these regions. The environmental variables analyzed were: maximum temperature; minimum temperature; mean temperature; precipitation; normalized difference vegetation index; relative humidity; altitude; and index of temperature and humidity. Records of weaning weight of Nellore cattle raised on pasture were collected between the years of 1997 and 2007. The dataset was constituted of 21.117 animals, progenies of 161 sires. (Co)variance components and breeding values were estimated using the multiple-trait derivative-free restricted maximum likelihood method. Multivariate spatialization revealed clear distinction among the States of Maranhão, Pará, and Tocantins and allowed the identification of important environmental variables for discrimination. The estimate for direct heritability showed moderate magnitudes and were 0.22±0013, 0.26±0.021, and 0.29±0023, for the States of Maranhão, Pará, and Tocantins, respectively. The estimates of correlation between the breeding values, predicted in different States, as well as the genetic correlation for weaning weight showed that sire ranks changed among the States, indicating G x E interaction. There was a variation of the genetic response of the progeny, depending on the sire and on the State. Thus, the G x E interaction should be accounted for in the genetic evaluation of sires and the performance of Nellore cattle under extensive breeding systems in tropical regions of Brazil.

Estimation of Genetic Parameters for 305 Days Milk Yields and Calving Interval in Xinjiang Brown Cattle

This study was conducted to estimate variance components and genetic parameters for 305 days mature equivalent milk yields (MEM) and calving interval (CAI) of registered Xinjiang Brown cattle. The total records were 3940 including 2579 for 305-day MEM and 1970 for CAI, which were collected from Xinjiang Urumqi Cattle Breeding farm in China with calving records from 1990 to 2008. Genetic parameters were obtained by multiple trait derivative-free restricted maximum likelihood (MTDFREML) using animal model. The model included year, season, parity and calving interval of calving for 305 days MEM, and year, season and parity of birth for CAI as fixed effects. Heritability for 305 days MEM was moderate (0.39) and in the same range of parameters estimated in management systems with medium production levels. Heritability of calving interval was small (0.02) as fertility traits for Xinjiang Brown cattle. Estimates of genetic and environmental correlations between 305 days MEM and CAI were 0.47 and 0.37, respectively. Estimates of genetic variation and heritability indicated that selection would result in genetic improvement of production traits. Estimates of both heritability and genetic variation for CAI were small, which indicates that genetic improvement would be difficult.

COMPARING GENETIC PARAMETERS OF FRIESIAN MILK PRODUCTION TRAITS IN COMMERCIAL AND STATE FARMS IN EGYPT

This study was conducted to estimate the genetic parameters for milk production traits of Friesian cattle in two selected dairy farms located in the Nile Delta of Egypt. A total of 1438 lactation records during the years2001 to 2009 were collected to represent 472 cows in Sakha Governmentfarm (SF). In comparison, a total of 1660 lactation records during the years 1998 to 2005 were collected to represent 465 cows in Gharbawy commercial (GF) farm. The derivative-free restricted maximum likelihood (REML) procedure was used to determine heritability, genetic correlation and breeding value of the studied traits. The results indicated that non genetic factors affecting lactation period (LP), total milk yield (TMY) and 305d -milk yield (305 d-MY) had highly significant (p < 0.001) effect on those traits except the effect of season of calving on TMY. Interaction between (herd & parity) and the interaction between (herd & parity & season) had highly significant effect (P< 0.001) on all milk production traits. The overall means of LP, TMY and 305-dMY were 313day; 4140kg; 3630 kg, respectively for cows in SF and as the corresponding values in GFwere 369.5day,8820Kg and 7430 kg. Estimates of direct heritability for LP, TMY, and 305MY in SF were 0.10, 0.11and 0.19 respectively, the corresponding estimates for GF were 0.10, 0.13 and 0.07 respectively on the other hand, estimates of maternal heritability for LP,TMY and 305MY in SF were 0.04, 0.07 and 0.06, respectively, while , the estimate in GF were 0.08, 0.09 and 0.12, respectively. The breeding values of sires estimated for LP,TMY and 305d-MY were 50.4, 27.4 and 42.3, respectively in SF, while the same estimates in GF were150.1, 20.04,and 30.7. The breeding values of cow concerning LP, TMY and 305MY in SF were 63.32, 45,4 and 21.5 while in GF, values were 195.1 , 29.9 , 53.2 , respectively . It can be concluded that improving environmental conditions and management practices, coupled with improved genetic potential of dairy animals in the state or commercial farms would be more effective approaches for high milk productivity.

The application of six different models to estimate the genetic parameters, variance components and breeding values for birth weight of Holstein calves

ABSTRACTThis research was conducted to determine variance component, genetic parameters and breeding values (EBV) for the birth weight (BW) of Holstein calves. In this context, the direct genetic (), maternal genetic () and maternal permanent environmental effects, which affect BW, were separately assessed. The multi-trait, derivative-free restricted maximum likelihood programme was used for determining the effect of the genetic parameters by using models that either included or excluded the maternal genetic and/or permanent maternal environmental effects. The estimation of the BW of Holstein calves was optimized by evaluating six different models. The best model was chosen according to the log-likelihood ratio tests. Within the context of the study, a total of 4443 calves were investigated between 1987 and 2006. Among the six different models, model 4 was selected as the best model, since it had the lowest value for the likelihood ratio. The range of the values for direct heritability () and maternal heritability (m2) were between 0.07–0.13 and 0.04–0.09, respectively. In conclusion, an estimation of the genetic parameters for BW can be used as a selection criteria for Holstein calves.

Comparison of Effectiveness of Animal Model Versus Sire Model for Different Growth Traits in Marwari Sheep

Growth traits records of lambs (1649) from 107 sires were used to evaluate the sires by estimating the breeding values using Best Linear Unbiased Prediction (BLUP) and Derivative-Free Restricted Maximum Likelihood (DFREML) methods. The average breeding values of Marwari sires for body weights at birth, weaning, 6, 9 and 12 months of age were estimated as 3.14, 15.13, 21.14, 25.85 and 28.86 kg, respectively, using BLUP method and 3.08, 15.13, 21.54, 26.48 and 29.20 kg, respectively, by DFREML method. For the average daily gains from birth to 3, 3 to 6 and 6 to12 months of age, the average breeding values were estimated as 133.60, 66.75 and 38.66 g, respectively by BLUP method, and 134.39, 71.02 and 36.88 g by DFREML method. DFREML was adjudged as more efficient and more stable method for sire evaluation than BLUP for all the traits under study on the basis of lower error variances and nearer coefficient of variation to the coefficient of variation of unadjusted records. DFREML was also considered to be a more accurate method of sire evaluation than BLUP for body weight at birth and six months of age. The higher rank co rrelations(>0.8) between BLUP and DFREML methods of sire evaluation for various growth traits indicated that there was a higher degree of similarity of ranking the sires (>80%) by both the methods of sire evaluation. Thus, DFREML has been recommended to be superior to BLUP for evaluation of breeding values of sires for different traits under study.

Estimation of genetic parameters and genetic changes for growth characteristics of Santa Ines sheep.

Studying genetic parameters and genetic changes in Santa Ines sheep is important, because it is the commonest breed in Brazil. This study obtained genetic data from 37,735 pedigree records of lambs over 12 years (2003-2014) from 33 flocks in 10 Brazilian States; 11,851 records of performance were available. (Co)variance components, genetic parameters and breeding values estimates were obtained by derivative-free restricted maximum likelihood in a univariate analysis that included maternal additive genetic and maternal permanent environmental effects. Birth weight, weaning weight, weight at 180 days of age, weight at 270 days of age, average daily weight gain in the following states: from birth to weaning, from weaning to 6 months, from 6 months to 9 months, and from weaning to 9 months; presence of hair in fur and leg muscularity were assessed. (Co)variance component values increased in the weight traits with age. A significant maternal effect was found in the pre-weaned stage that decreased in the post-weaned stage. High values were estimated for the maternal permanent environmental effect, possibly because of the extensive grassland that was available. High total heritability values were estimated for all of the traits evaluated. Significant, positive correlations were found between direct and maternal additive genetic traits with a gradual decrease as the lambs gained independence from their mothers. The genetic trends observed were irregular and incremental. Significant genetic variance suggests that direct selection for pre-weaning traits results in indirect selection of maternal abilities, and individual selection of any post-weaning trait results in rapid genetic improvement.

Estimation of genetic and phenotypic parameters for production traits in Holstein and Jersey from Colombia

ABSTRACT Objective. Determine the genetic and phenotypic parameters for milk yield, fat percentage, protein percentage and somatic cell score. Materials and methods. 18134 lactation records were used to Holstein and 1377 lactations for Jersey in different herds. The (co) variance components and genetic parameters were estimated using the software Multiple Trait Derivative-Free Restricted Maximum Likelihood MTDFREML. Results. The Holstein and Jersey heritability’s (and standard error) for milk yield were: 0.16 (0.082) and 0.15 (0.306), 0.30 (0.079) and 0.37 (0.319) for protein percentage, 0.32 (0.076) and 0.46 (0.313) for fat percentage and for somatic cell score were: 0.01 (0.054) and 0.01 (0.233), respectively. The largest genetic correlations were found between the percentage of fat and percentage of protein, with values of 0.82 (0.126) and 0.98 (0.852) for Holstein and Jersey respectively. The lowest correlations were between fat percentage and somatic cell score with -0.01 (1.147) and -0.01 (1. 734). Phenotypic correlations were generally found low and repeatability showed a significant effect of permanent environment on milk production per lactation. Conclusions. It is important to emphasize the development of research to help guide breeding programs in the tropics, using selection indices of multi-traits.

Estimation of Genetic Parameters for Pork Belly Components in Yorkshire Pigs.

This study was conducted to estimate the genetic parameters for pork belly traits and muscles in Yorkshire pigs. Each pork belly was cut into nine parts perpendicular to the thoracic vertebrae (6th to 14th). Traits of belly muscles including the deep pectoral, latissimus dorsi, cutaneous trunci, rectus abdominis, external and internal abdominal oblique from 382 purebred pigs were recorded and analyzed using SAS Package (9.1) and Derivative-free restricted maximum likelihood methods. Heritability estimates for belly traits ranged from 0.27 to 0.49, while they were 0.12 to 0.66 for belly muscles. Moderate to high heritability estimates were noted in belly weight (0.33), belly length (0.28), and belly width (0.49). In belly muscles, the latissimus dorsi and deep pectoral, which are located only in the 6th to 9th vertebrae sections, were found to have heritability estimates ranging from 0.21 to 0.29 and 0.23 to 0.35, respectively. Strong heritability estimates were observed in the 7th to 13th sections of cutaneous trunci muscle ranging from 0.42 to 0.66. Genetic correlations of latissimus dorsi m. with belly length were positive (0.50), while cutaneous trunci m. with belly weight also revealed a positive relationship that ranged from 0.35 to 0.47. The estimated genetic parameters indicate that belly weight can be improved by genetic selection. Differences in the levels of heritability occurred among various parameters of Yorkshire pork belly, which should be considered when performing selection to improve pork belly quality. Moreover, these results can provide valuable information that can be used as the basis for further investigations to improve pork belly.

Estimates of heritability and correlation for growth traits of turbot (Scophthalmus maximus L.) under low temperature conditions

The objectives of this present research were to assess the heritability of growth traits under low temperature conditions in turbot (Scophthalmus maximus L.), and to analyze the correlation between body weight (BW) and body length (BL). There were 536 individuals from 25 full- and half-sib families involved in this study. During the entire 90-day period, which was initiated at 233 dph (day old) and ended at 323 dph, the individuals’ BW and BL were weighed consecutively six times every 18 days. The heritability of BW and BL and the correlation between these two traits were estimated based on an individual animal model with the derivative-free restricted maximum likelihood (DFREML) method. These results showed that the specific growth rates (SGR) of 25 families was from 0.75±0.11 to 1.05±0.14 under water temperature of 10.5–12°C. In addition, the heritability of BW and BL estimated under low-temperature were 0.32±0.04 and 0.47±0.06, respectively. The BW had a medium heritability (0.2–0.4), and the BL had a high heritability (>0.45), which suggested that selection for increased weight and length was feasible. Moreover, there was potential for mass selection on growth. The genetic and phenotypic correlations between BW and BL were 0.95±0.01 and 0.91±0.01 (P < 0.01), respectively. A significant correlation between BW and BL showed that BL could be instead of BW for indirect selection, which could be effectively implemented in the breeding program.