Genome-wide association study applied to type traits related to milk yield in water buffaloes (Bubalus bubalis).

This research aimed to estimate genetic parameters for milk yield and type traits [withers height (WH), croup height (CH), body length (BL), croup length (CL), iliac width (ILW), ischial width (ISW), and thoracic circumference] in Murrah buffaloes and to identify genomic regions related to type traits by applying a single-step genome-wide association study. Data used to estimate the genetic parameters consisted of 601 records of milk yield in the first lactation and the aforementioned type traits. For the single-step genome-wide association study, 322 samples genotyped with a 90K Axiom Buffalo Genotyping array (Thermo Fisher Scientific, Santa Clara, CA) were used. Bivariate analysis revealed that heritability for milk yield (kg) at 305 d was 0.31 ± 0.11, whereas it ranged from 0.22 ± 0.07 to 0.34 ± 0.09 for the studied conformation traits. Based on the percentages of genetic variance explained by windows of 10 markers, there were 16 genomic regions explaining more than 0.5% of the variance for WH, CH, BL, CL, ILW, ISW, and thoracic circumference. Between those regions, 4 were associated with more than 1 trait, suggesting pleiotropic roles for some genes of Bos taurus autosome (BTA) 12 on CL and WH, BTA13 on ISW and ILW, BTA23 on CH and BL, and BTA28 on ISW and BL. Most of these regions coincide with known quantitative trait loci for milk traits. Thus, further studies based on sequence data will help to validate the association of this region with type traits and likely identify the causal mutations.

Genomic analysis of stayability in Nellore cattle.

Stayability, which can be defined as the probability of a cow calving at a certain age when given the opportunity, is an important reproductive trait in beef cattle because it is directly related to herd profitability. The objective of this study was to estimate genetic parameters and to identify possible genomic regions associated with the phenotypic expression of stayability in Nellore cows. The variance components were estimated by Bayesian inference using a threshold animal model that included the systematic effects of contemporary group and sexual precocity and the random effects of animal and residual. The SNP effects were estimated by the single-step genomic BLUP method using information of 2,838 animals (2,020 females and 930 sires) genotyped with the Illumina High-Density BeadChip Array (San Diego, CA, USA). The variance explained by windows formed by 200 consecutive SNPs was used to identify genomic regions of largest effect on the expression of stayability. The heritability was 0.11 ± 0.01 when A matrix (pedigree) was used and 0.14 ± 0.01 when H matrix (relationship matrix that combines pedigree information and SNP data) was used. A total of 147 candidate genes for stayability were identified on chromosomes 1, 2, 5, 6, 9 and 20 and on the X chromosome. New candidate regions for stayability were detected, most of them related to reproductive, immunological and central nervous system functions.

Genome-Wide Association Study for Carcass Traits in an Experimental Nelore Cattle Population.

The purpose of this study was to identify genomic regions associated with carcass traits in an experimental Nelore cattle population. The studied data set contained 2,306 ultrasound records for longissimus muscle area (LMA), 1,832 for backfat thickness (BF), and 1,830 for rump fat thickness (RF). A high-density SNP panel (BovineHD BeadChip assay 700k, Illumina Inc., San Diego, CA) was used for genotyping. After genomic data quality control, 437,197 SNPs from 761 animals were available, of which 721 had phenotypes for LMA, 669 for BF, and 718 for RF. The SNP solutions were estimated using a single-step genomic BLUP approach (ssGWAS), which calculated the variance for windows of 50 consecutive SNPs and the regions that accounted for more than 0.5% of the additive genetic variance were used to search for candidate genes. The results indicated that 12, 18, and 15 different windows were associated to LMA, BF, and RF, respectively. Confirming the polygenic nature of the studied traits, 43, 65, and 53 genes were found in those associated windows, respectively for LMA, BF, and RF. Among the candidate genes, some of them, which already had their functions associated with the expression of energy metabolism, were found associated with fat deposition in this study. In addition, ALKBH3 and HSD17B12 genes, which are related in fibroblast death and metabolism of steroids, were found associated with LMA. The results presented here should help to better understand the genetic and physiologic mechanism regulating the muscle tissue deposition and subcutaneous fat cover expression of Zebu animals. The identification of candidate genes should contribute for Zebu breeding programs in order to consider carcass traits as selection criteria in their genetic evaluation.

Performance, intake and feed efficiency of Nellore young bulls housed in individual or group pens / Desempenho, consumo e eficiência alimentar de bovinos Nelore confinados em baias individuais ou coletivas

Feed is the most expensive input in any livestock production system including beef cattle, therefore feed efficiency improvements can contribute to cost reduction. Residual feed intake (RFI) is one of the important measures of animal efficiency and can be defined as the difference between actual feed intake (measure at individual or group pens) and predicted feed intake that is required for the observed rate of gain and body weight (BW). The objective here was to evaluate the housing type (individual or group) on variation of traits such as dry matter intake (DMI, kg/d and %BW), average daily gain (ADG), RFI and gain:feed (G:F) in a dataset of Nellore young bulls obtained from performance tests of 83±16 days long after adaptation period, conducted between 2007 and 2013. The animals (273 ± 27 days of age at the beginning of the test) were obtained from selected, traditional and control Nellore lines of Instituto de Zootecnia. The animals were housed in individuals pens (IP) (2007-2012) or group pens (GP) (2012-2013) equipped with the GrowSafe® system (voluntary intake calculated automatically by the system). In IP, animals were fed twice a day and had water available all the time. Voluntary food intake was calculated as the difference between supplied and refused food. Leftovers were collected daily, weighed, and then adjusted to correspond to 10% of the total supplied. A mixed

O artigo não apresenta resumo em português.

Genetic and phenotypic correlations of feed efficiency with growth traits in Nellore cattle / Correlações genética e fenotípica entre características de eficiência alimentar e características de crescimento em bovinos Nelore

Feed efficiency is difficult to evaluate because individual feeding are required. An alternative is selecting animals based on traits easier to obtain and genetically favorably correlated with feed efficiency traits. This study aimed to estimate genetic and phenotypic correlations between feed efficiency traits (residual feed intake RFI, feed efficiency FE and residual BW gain RG) with yearling weight (YW), hip height (HH) and girth circumference (GC) in Nellore cattle. Feed efficiency data set consisted of 887 records of DMI, ADG and BW0.75 obtained during performance tests (83 ± 15 d) to calculate RFI (0.005 ± 0.58 kg DM/d), FE (0.14 ± 0.03) and RG (0.00 ± 0.11 kg/d). FE was calculated as ADG and DMI ratio, RFI was estimated as the error of multiple regression of DMI on ADG and BW0.75, and RG was estimated as the error of multiple regression of ADG on DMI and BW0.75. The YW data set consisted of 7,948 records of males (314.45 ± 45.85 kg) and females (282.68 ± 48.19 kg) adjusted to 378 and 550 d of age, respectively. The HH consisted of 6,418 records of males (131.80 ± 5.40 cm) and females (132.51 ± 5.38 cm), and 3,745 records of GC of males (162.56 ± 8.48 cm) and females (167.72 ± 8.08 cm). Pedigree file contained 9,830 animals. Growth traits were analyzed as unit standard deviation of each sex/age. (Co)variance components were estimated through two-trait animal models

O artigo não apresenta resumo em português.

Feeding behavior variation of Nellore cattle classified by residual feed intake during efficiency test / Variação em comportamento alimentar de bovinos Nelore classificados por consumo alimentar residual durante o teste de eficiência

This study aimed to evaluate feed intake and behavior during feed efficiency test of Nellore males from different residual feed intake (RFI) classes. Data from 85 Nellore males, with initial average age of 270 ± 23 days and body weight of 239 ± 41 kg were used. The feed efficiency test was performed during 119 days, divided in four periods. The first period (adaptation) had 28 days, and the three subsequent periods had, respectively, 28, 28 and 31 days. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI) individual data. After test end, RFI was calculated by the difference between observed and predicted feed intake, based on average daily gain and metabolic body weight. Then, animals were classified into low ( mean - 0.5 standard deviation-SD), medium (± 0.5 SD from mean) and high (>mean + 0.5 SD) RFI. Statistical analyzes were performed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model effects of test period (1, 2, 3 or 4), RFI classes (low, medium or high) and interaction, being animal age considered as linear covariate. Feeding behavior pattern was not different among the efficiency test periods (P>0.05), however differences were detected among RFI classes inside the periods (P 0.01) (Figure 1). Low RFI animals, when compared to the medium and high RFI

O artigo não apresenta resumo em português.

Patterns of feed intake and behavior during efficiency test of Nelore males / Padrão de consumo e comportamento alimentar durante o teste de eficiência em machos Nelore

The present study aimed to evaluate feed intake and behavior during the efficiency test of Nellore males. Efficiency test was conducted from June to October of 2012, during 119 days. Registers of 85 Nellore males, with initial averages age of 270 ± 23 days and body weight of 239 ± 41 kg were used. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which individual recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI). The first 28 days of test were for adaptation to diet and environment, and the subsequent 91 days were considered as experimental period. Experimental period was divided in three sub periods (28, 28 and 31 days, respectively). Data were analyzed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model period effects (adaptation - 1 and experimental periods - 2, 3 or 4) and animal age as linear covariate. During the adaptation period, low values (P 0.05) were observed of FI, BA and FV (991 ± 40.7 kg/day, 854 ± 33.2 min/day and 1172 ± 49.4 visits/day, respectively) in relation experimental period (1091 ± 18.5 kg/day, 965 ± 15.1 min/day and 1217 ± 22.5 visits/day, respectively). Feeding behavior traits were analyzed in four test periods (Figure 1), and a reduction (P 0.05) in FI (from 1162 ± 39.2 to 984 ± 77.6 kg/day) and BA (from 992 ± 32.1 to 866 ± 63.6 min/day) was observed in the third period. Additionally, FV m

O artigo não apresenta resumo em português.

Patterns of feed intake and behavior during efficiency test of Nelore males / Padrão de consumo e comportamento alimentar durante o teste de eficiência em machos Nelore

The present study aimed to evaluate feed intake and behavior during the efficiency test of Nellore males. Efficiency test was conducted from June to October of 2012, during 119 days. Registers of 85 Nellore males, with initial averages age of 270 ± 23 days and body weight of 239 ± 41 kg were used. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which individual recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI). The first 28 days of test were for adaptation to diet and environment, and the subsequent 91 days were considered as experimental period. Experimental period was divided in three sub periods (28, 28 and 31 days, respectively). Data were analyzed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model period effects (adaptation - 1 and experimental periods - 2, 3 or 4) and animal age as linear covariate. During the adaptation period, low values (P 0.05) were observed of FI, BA and FV (991 ± 40.7 kg/day, 854 ± 33.2 min/day and 1172 ± 49.4 visits/day, respectively) in relation experimental period (1091 ± 18.5 kg/day, 965 ± 15.1 min/day and 1217 ± 22.5 visits/day, respectively). Feeding behavior traits were analyzed in four test periods (Figure 1), and a reduction (P 0.05) in FI (from 1162 ± 39.2 to 984 ± 77.6 kg/day) and BA (from 992 ± 32.1 to 866 ± 63.6 min/day) was observed in the third period. Additionally, FV m

O artigo não apresenta resumo em português.

Feeding behavior variation of Nellore cattle classified by residual feed intake during efficiency test / Variação em comportamento alimentar de bovinos Nelore classificados por consumo alimentar residual durante o teste de eficiência

This study aimed to evaluate feed intake and behavior during feed efficiency test of Nellore males from different residual feed intake (RFI) classes. Data from 85 Nellore males, with initial average age of 270 ± 23 days and body weight of 239 ± 41 kg were used. The feed efficiency test was performed during 119 days, divided in four periods. The first period (adaptation) had 28 days, and the three subsequent periods had, respectively, 28, 28 and 31 days. Animals were fed ad libitum at GrowSafe System® with 10 feeders, which recorded bunk attendance (BA), frequency of visits (FV) and feed intake (FI) individual data. After test end, RFI was calculated by the difference between observed and predicted feed intake, based on average daily gain and metabolic body weight. Then, animals were classified into low ( mean - 0.5 standard deviation-SD), medium (± 0.5 SD from mean) and high (>mean + 0.5 SD) RFI. Statistical analyzes were performed by PROC MIXED (SAS Inst., Inc., Cary, NC), including in the model effects of test period (1, 2, 3 or 4), RFI classes (low, medium or high) and interaction, being animal age considered as linear covariate. Feeding behavior pattern was not different among the efficiency test periods (P>0.05), however differences were detected among RFI classes inside the periods (P 0.01) (Figure 1). Low RFI animals, when compared to the medium and high RFI

O artigo não apresenta resumo em português.

Genetic and phenotypic correlations of feed efficiency with growth traits in Nellore cattle / Correlações genética e fenotípica entre características de eficiência alimentar e características de crescimento em bovinos Nelore

Feed efficiency is difficult to evaluate because individual feeding are required. An alternative is selecting animals based on traits easier to obtain and genetically favorably correlated with feed efficiency traits. This study aimed to estimate genetic and phenotypic correlations between feed efficiency traits (residual feed intake RFI, feed efficiency FE and residual BW gain RG) with yearling weight (YW), hip height (HH) and girth circumference (GC) in Nellore cattle. Feed efficiency data set consisted of 887 records of DMI, ADG and BW0.75 obtained during performance tests (83 ± 15 d) to calculate RFI (0.005 ± 0.58 kg DM/d), FE (0.14 ± 0.03) and RG (0.00 ± 0.11 kg/d). FE was calculated as ADG and DMI ratio, RFI was estimated as the error of multiple regression of DMI on ADG and BW0.75, and RG was estimated as the error of multiple regression of ADG on DMI and BW0.75. The YW data set consisted of 7,948 records of males (314.45 ± 45.85 kg) and females (282.68 ± 48.19 kg) adjusted to 378 and 550 d of age, respectively. The HH consisted of 6,418 records of males (131.80 ± 5.40 cm) and females (132.51 ± 5.38 cm), and 3,745 records of GC of males (162.56 ± 8.48 cm) and females (167.72 ± 8.08 cm). Pedigree file contained 9,830 animals. Growth traits were analyzed as unit standard deviation of each sex/age. (Co)variance components were estimated through two-trait animal models

O artigo não apresenta resumo em português.

Performance, intake and feed efficiency of Nellore young bulls housed in individual or group pens / Desempenho, consumo e eficiência alimentar de bovinos Nelore confinados em baias individuais ou coletivas

Feed is the most expensive input in any livestock production system including beef cattle, therefore feed efficiency improvements can contribute to cost reduction. Residual feed intake (RFI) is one of the important measures of animal efficiency and can be defined as the difference between actual feed intake (measure at individual or group pens) and predicted feed intake that is required for the observed rate of gain and body weight (BW). The objective here was to evaluate the housing type (individual or group) on variation of traits such as dry matter intake (DMI, kg/d and %BW), average daily gain (ADG), RFI and gain:feed (G:F) in a dataset of Nellore young bulls obtained from performance tests of 83±16 days long after adaptation period, conducted between 2007 and 2013. The animals (273 ± 27 days of age at the beginning of the test) were obtained from selected, traditional and control Nellore lines of Instituto de Zootecnia. The animals were housed in individuals pens (IP) (2007-2012) or group pens (GP) (2012-2013) equipped with the GrowSafe® system (voluntary intake calculated automatically by the system). In IP, animals were fed twice a day and had water available all the time. Voluntary food intake was calculated as the difference between supplied and refused food. Leftovers were collected daily, weighed, and then adjusted to correspond to 10% of the total supplied. A mixed

O artigo não apresenta resumo em português.

Relationships between feeding behavior and average daily gain in cattle / Relações entre comportamento alimentar e classes de ganho médio diário em bovinos

Several studies have reported relationship between eating behavior and performance in feedlot cattle. The evaluation of behavior traits demands high degree of work and trained manpower, therefore, in recent years has been used an automated feed intake measurement system (GrowSafe System ®), that identify and record individual feeding patterns. The aim of this study was to evaluate the relationship between feeding behavior traits and average daily gain in Nellore calves undergoing feed efficiency test. Date from 85 Nelore males was recorded during the feed efficiency test performed in 2012, at Centro APTA Bovinos de Corte, Instituto de Zootecnia, São Paulo State. Were analyzed the behavioral traits: time at feeder (TF), head down duration (HD), representing the time when the animal is actually eating, frequency of visits (FV) and feed rate (FR) calculated as the amount of dry matter (DM) consumed by time at feeder (g.min-1). The ADG was calculated by linear regression of individual weights on days in test. ADG classes were obtained considering the average ADG and standard deviation (SD) being: high ADG (>mean + 1.0 SD), medium ADG (± 1.0 SD from the mean) and low ADG ( mean - 1.0 SD). Data were analyzed using the PROC MIXED procedure (SAS 9.3). The model included animal and residue as random effects and the fixed effects of ADG class (1, 2 and 3) and age at the middle of t

O artigo não apresenta resumo em português.

Genetic trend for lactation persistency in Gyr cows / Tendência genética para persistência da lactação em vacas Gir leiteiro

Persistency can be dened as the degree to which production is maintained after peak yield is reached. In Gyr cattle, persistency is an obstacle in milk production and profitability. So, persistency is an important trait that must be evaluated with total milk production in Brazilian Gyr cattle. The objective of this study was to calculate genetic tendency for persistency, accumulated 305-day milk yield and partial milk yields in first 100, 200 and 300 days in milk of Brazilian Gyr cows using breeding values predicted (EBV) by random regression models. Data was obtained from ABCZ and included 15052 first lactations from cows with calving year ranged from 1980 to 2006. Fixed effects was contemporary group (milking herd, year and season of milk control) and the days in milk were modeled using Legendre polynomials of order 4 for additive genetic and permanent environmental random effects and a heterogeneous residual variance structure using four classes. To estimate breeding values for 305-day milk yield, the daily EBV were added. To calculate the EBVs for partial periods was made the sum of EBVs daily in the first 100 days (P100), between 100 and 200 days (P200) and between 200 and 300 days (P300) in lactation. Persistency was obtained by the sum of the deviations of EBVs predicted between 30 and 270 days of production in relation to EBV predicted for peak production. The EBV for

O artigo não apresenta resumo em português.

Genetic trend for lactation persistency in Gyr cows / Tendência genética para persistência da lactação em vacas Gir leiteiro

Persistency can be dened as the degree to which production is maintained after peak yield is reached. In Gyr cattle, persistency is an obstacle in milk production and profitability. So, persistency is an important trait that must be evaluated with total milk production in Brazilian Gyr cattle. The objective of this study was to calculate genetic tendency for persistency, accumulated 305-day milk yield and partial milk yields in first 100, 200 and 300 days in milk of Brazilian Gyr cows using breeding values predicted (EBV) by random regression models. Data was obtained from ABCZ and included 15052 first lactations from cows with calving year ranged from 1980 to 2006. Fixed effects was contemporary group (milking herd, year and season of milk control) and the days in milk were modeled using Legendre polynomials of order 4 for additive genetic and permanent environmental random effects and a heterogeneous residual variance structure using four classes. To estimate breeding values for 305-day milk yield, the daily EBV were added. To calculate the EBVs for partial periods was made the sum of EBVs daily in the first 100 days (P100), between 100 and 200 days (P200) and between 200 and 300 days (P300) in lactation. Persistency was obtained by the sum of the deviations of EBVs predicted between 30 and 270 days of production in relation to EBV predicted for peak production. The EBV for

O artigo não apresenta resumo em português.

Relationships between feeding behavior and average daily gain in cattle / Relações entre comportamento alimentar e classes de ganho médio diário em bovinos

Several studies have reported relationship between eating behavior and performance in feedlot cattle. The evaluation of behavior traits demands high degree of work and trained manpower, therefore, in recent years has been used an automated feed intake measurement system (GrowSafe System ®), that identify and record individual feeding patterns. The aim of this study was to evaluate the relationship between feeding behavior traits and average daily gain in Nellore calves undergoing feed efficiency test. Date from 85 Nelore males was recorded during the feed efficiency test performed in 2012, at Centro APTA Bovinos de Corte, Instituto de Zootecnia, São Paulo State. Were analyzed the behavioral traits: time at feeder (TF), head down duration (HD), representing the time when the animal is actually eating, frequency of visits (FV) and feed rate (FR) calculated as the amount of dry matter (DM) consumed by time at feeder (g.min-1). The ADG was calculated by linear regression of individual weights on days in test. ADG classes were obtained considering the average ADG and standard deviation (SD) being: high ADG (>mean + 1.0 SD), medium ADG (± 1.0 SD from the mean) and low ADG ( mean - 1.0 SD). Data were analyzed using the PROC MIXED procedure (SAS 9.3). The model included animal and residue as random effects and the fixed effects of ADG class (1, 2 and 3) and age at the middle of t

O artigo não apresenta resumo em português.

Genetic evaluation of temperament trait by visual score in Nellore cattle / Avaliação genética da característica de temperamento por escore visual em bovinos Nelore

The national herd is predominantly composed by Nelore breed (Bos indicus), being extremely important for beef cattle, even though, it have limitations as aggressive temperament compared to populations of Bos taurus origin. The temperament (TEMP) can be defined as the perception and reaction of the animals when they feel fear or are managed by man. More reactive cattle have lower weight gain, produce beef of lower quality, are more susceptible to diseases and have low reproductive performance. The objective of this research was to obtain the components of (co) variances and genetic parameters of TEMP in order to provide subsidies to farmers and technicians on its use in animal breeding programs. For the TEMP trait, the database used was from the Nelore breeding program Nelore Qualitas. Data was recorded from 2000 to 2009, on 20 farms across six Brazilian states, on 48,879 males and females ranging in age from 450 to 599 days. TEMP trait was performed by visual scores, in 1-5 scale, where higher scores means less reactive animals. The genetic parameters were estimated with univariate animal model and Bayesian inference, using the program GIBBS2F90. The statistical model included fixed effects of contemporary group, age at measurement as a linear covariate, and random effects of additive genetic and residual. The data set included 455 sires, 28,111 dams and 3,153 contemporary gr

O artigo não apresenta resumo em português.

Genetic evaluation of temperament trait by visual score in Nellore cattle / Avaliação genética da característica de temperamento por escore visual em bovinos Nelore

The national herd is predominantly composed by Nelore breed (Bos indicus), being extremely important for beef cattle, even though, it have limitations as aggressive temperament compared to populations of Bos taurus origin. The temperament (TEMP) can be defined as the perception and reaction of the animals when they feel fear or are managed by man. More reactive cattle have lower weight gain, produce beef of lower quality, are more susceptible to diseases and have low reproductive performance. The objective of this research was to obtain the components of (co) variances and genetic parameters of TEMP in order to provide subsidies to farmers and technicians on its use in animal breeding programs. For the TEMP trait, the database used was from the Nelore breeding program Nelore Qualitas. Data was recorded from 2000 to 2009, on 20 farms across six Brazilian states, on 48,879 males and females ranging in age from 450 to 599 days. TEMP trait was performed by visual scores, in 1-5 scale, where higher scores means less reactive animals. The genetic parameters were estimated with univariate animal model and Bayesian inference, using the program GIBBS2F90. The statistical model included fixed effects of contemporary group, age at measurement as a linear covariate, and random effects of additive genetic and residual. The data set included 455 sires, 28,111 dams and 3,153 contemporary gr

O artigo não apresenta resumo em português.

Genotype-environment interaction in the genetic analysis for weaning weight in Nelore cattle using bayesian approach - doi: 10.4025/actascianimsci.v33i2.8469 / Interação genótipo-ambiente na análise genética do peso ao desmame de bovinos Nelore sob enfoque bayesiano - doi: 10.4025/actascianimsci.v33i2.8469

The objective was to evaluate the interactions of genotype-environment effects on the components of (co)variance estimates and the prediction of breeding values for weaning weight in Nelore cattle, using a Bayesian approach. Records of 16,644 weaning weights were used from cattle distributed in ten ranches across six Brazilian states. The genetic parameters were estimated under an animal model considering Bayesian statistics. To verify genotype-environment interaction effects, we analyzed the following matrix model: without the inclusion of genotype-environment interaction effects, and with the inclusion of genotype-environment interaction effects, which considered the effect of sire-year, sire-herd, and both effects. In general, the results suggest that the inclusion of genotype-environment interaction in genetic analysis for weight at weaning tends to alter the estimates of genetic and environment (co)variances. The Spearman correlations between the breeding values were above 97%, indicating practically no change in the classification of animals evaluated. It can be inferred that the interaction effects of sire-year and sire-herd do not change the animals rank, and if not included in the genetic evaluation, the selection based on predictions of breeding values for weaning weight will not be affected.

Objetivou-se avaliar os efeitos das interações genótipo-ambiente sobre as estimativas de componentes de (co)variâncias e predição dos valores genéticos para o peso ao desmame de bovinos Nelore, sob enfoque bayesiano. Foram utilizados 16.644 registros de pesos ao desmame de bovinos provenientes de dez rebanhos participantes do Programa Nelore Brasil. Os parâmetros genéticos foram estimados sob modelo animal, considerando a estatística bayesiana. Para verificar o efeito da interação genótipo-ambiente, foram analisados os seguintes modelos matriciais: sem a inclusão dos efeitos de interação genótipo-ambiente; com a inclusão dos efeitos de interação genótipo-ambiente, em que se considerou o efeito de touro-ano, touro-rebanho e ambos os efeitos. De modo geral, verifica-se que a inclusão da interação genótipo-ambiente na análise genética para o peso ao desmame, tende a alterar as estimativas de (co)variâncias genéticas e ambientais. As correlações de Spearman entre os valores genéticos foram acima de 97%, indicando que, praticamente, não houve mudança na classificação dos animais avaliados. Pode se inferir que os efeitos de interação touro-ano e touro-rebanho não alteram as classificações dos animais, e a não-inclusão destes efeitos na avaliação genética, não afetam a seleção baseada nas predições dos valores genéticos para o peso ao desmame.

Genotype-environment interaction in the genetic analysis for weaning weight in Nelore cattle using bayesian approach - doi: 10.4025/actascianimsci.v33i2.8469 / Interação genótipo-ambiente na análise genética do peso ao desmame de bovinos Nelore sob enfoque bayesiano - doi: 10.4025/actascianimsci.v33i2.8469

The objective was to evaluate the interactions of genotype-environment effects on the components of (co)variance estimates and the prediction of breeding values for weaning weight in Nelore cattle, using a Bayesian approach. Records of 16,644 weaning weights were used from cattle distributed in ten ranches across six Brazilian states. The genetic parameters were estimated under an animal model considering Bayesian statistics. To verify genotype-environment interaction effects, we analyzed the following matrix model: without the inclusion of genotype-environment interaction effects, and with the inclusion of genotype-environment interaction effects, which considered the effect of sire-year, sire-herd, and both effects. In general, the results suggest that the inclusion of genotype-environment interaction in genetic analysis for weight at weaning tends to alter the estimates of genetic and environment (co)variances. The Spearman correlations between the breeding values were above 97%, indicating practically no change in the classification of animals evaluated. It can be inferred that the interaction effects of sire-year and sire-herd do not change the animals rank, and if not included in the genetic evaluation, the selection based on predictions of breeding values for weaning weight will not be affected.

Objetivou-se avaliar os efeitos das interações genótipo-ambiente sobre as estimativas de componentes de (co)variâncias e predição dos valores genéticos para o peso ao desmame de bovinos Nelore, sob enfoque bayesiano. Foram utilizados 16.644 registros de pesos ao desmame de bovinos provenientes de dez rebanhos participantes do Programa Nelore Brasil. Os parâmetros genéticos foram estimados sob modelo animal, considerando a estatística bayesiana. Para verificar o efeito da interação genótipo-ambiente, foram analisados os seguintes modelos matriciais: sem a inclusão dos efeitos de interação genótipo-ambiente; com a inclusão dos efeitos de interação genótipo-ambiente, em que se considerou o efeito de touro-ano, touro-rebanho e ambos os efeitos. De modo geral, verifica-se que a inclusão da interação genótipo-ambiente na análise genética para o peso ao desmame, tende a alterar as estimativas de (co)variâncias genéticas e ambientais. As correlações de Spearman entre os valores genéticos foram acima de 97%, indicando que, praticamente, não houve mudança na classificação dos animais avaliados. Pode se inferir que os efeitos de interação touro-ano e touro-rebanho não alteram as classificações dos animais, e a não-inclusão destes efeitos na avaliação genética, não afetam a seleção baseada nas predições dos valores genéticos para o peso ao desmame.

Bayesian estimation of (co)variance components for growth traits in tabapuã cattle / Estimação bayesiana de componentes de (co)variância de características ponderais na raça tabapuã

Among the features of interest to the animal breeding, that can be measured repeatedly throughout an individual"s life, are among other, growth characteristics, which are characteristic features called longitudinal or repeated. It was used 8193 Tabapuã breed records of animal weight raised in 25 farms distributed in the states of Bahia, Alagoas, Sergipe, Minas Gerais and São Paulo and born between the years of 1975 and 2001. Aiming to estimate the (co) variance and genetic parameters for weights at 120 (W120), 365 (W365), 450 (W450) e 550 (W550) days old. Variance components were estimated in a Bayesian context considering a multi-trait animal model with fixed effects for contemporary groups and ages of the mother and the animal. The random effects were considered direct genetic and maternal and maternal permanent environment and error. The effects mothers were included in the model only for W120 and W365. The direct heritability were 0.31, 0.38, 0.33 and 0.29 for W120, W365, W450 and W550, respectively. The fractions of genetic and maternal permanent environment effects on phenotypic variances were 0.06 and 0.01, 0.03 and 0.01 for W120 and W365.

Entre as características de interesse para o melhoramento genético animal que podem ser mensuradas repetidamente ao longo da vida do indivíduo, encontram-se, entre outras, as características de crescimento, que são denominadas características repetidas ou longitudinais. Foram utilizados 8.193 registros de peso de animais da raça Tabapuã criados em 25 fazendas distribuídas nos estados da Bahia, Alagoas, Sergipe, Minas Gerais e São Paulo, nascidos entre os anos de 1975 e 2001, com o objetivo de estimar componentes de (co)variância e parâmetros genéticos para pesos aos 120 (P120), 365 (P365), 450 (P450) e 550 (P550) dias de idade. Os componentes de variância foram mensurados em um contexto bayesiano, considerando um modelo animal multi-característica com efeitos fixos de grupos de contemporâneos e as idades da mãe e do animal. Os efeitos aleatórios considerados foram o genético direto e materno e o de ambiente permanente materno e o erro. Os efeitos maternos foram incluídos no modelo somente para P120 e P365. As herdabilidades diretas foram 0,31; 0,38; 0,33 e 0,29 para P120, P365, P450 e P550, respectivamente. As frações dos efeitos genéticos e de ambiente permanente materno na variância fenotípica foram: 0,06 e 0,01; 0,03 e 0,01 para P120 e P365.