Assessment of inbreeding coefficients and inbreeding depression on complex traits from genomic and pedigree data in Nelore cattle.

BACKGROUND: Nelore cattle play a key role in tropical production systems due to their resilience to harsh conditions, such as heat stress and seasonally poor nutrition. Monitoring their genetic diversity is essential to manage the negative impacts of inbreeding. Traditionally, inbreeding and inbreeding depression are assessed by pedigree-based coefficients (F), but recently, genetic markers have been preferred for their precision in capturing the inbreeding level and identifying animals at risk of reduced productive and reproductive performance. Hence, we compared the inbreeding and inbreeding depression for productive and reproductive performance traits in Nelore cattle using different inbreeding coefficient estimation methods from pedigree information (FPed), the genomic relationship matrix (FGRM), runs of homozygosity (FROH) of different lengths (> 1 Mb (genome), between 1 and 2 Mb - FROH 1-2; 2-4 Mb FROH 2-4 or > 8 Mb FROH >8) and excess homozygosity (FSNP). RESULTS: The correlation between FPed and FROH was lower when the latter was based on shorter segments (r = 0.15 with FROH 1-2, r = 0.20 with FROH 2-4 and r = 0.28 with FROH 4-8). Meanwhile, the FPed had a moderate correlation with FSNP (r = 0.47) and high correlation with FROH >8 (r = 0.58) and FROH-genome (r = 0.60). The FROH-genome was highly correlated with inbreeding based on FROH>8 (r = 0.93) and FSNP (r = 0.88). The FGRM exhibited a high correlation with FROH-genome (r = 0.55) and FROH >8 (r = 0.51) and a lower correlation with other inbreeding estimators varying from 0.30 for FROH 2-4 to 0.37 for FROH 1-2. Increased levels of inbreeding had a negative impact on the productive and reproductive performance of Nelore cattle. The unfavorable inbreeding effect on productive and reproductive traits ranged from 0.12 to 0.51 for FPed, 0.19-0.59 for FGRM, 0.21-0.58 for FROH-genome, and 0.19-0.54 for FSNP per 1% of inbreeding scaled on the percentage of the mean. When scaling the linear regression coefficients on the standard deviation, the unfavorable inbreeding effect varied from 0.43 to 1.56% for FPed, 0.49-1.97% for FGRM, 0.34-2.2% for FROH-genome, and 0.50-1.62% for FSNP per 1% of inbreeding. The impact of the homozygous segments on reproductive and performance traits varied based on the chromosomes. This shows that specific homozygous chromosome segments can be signs of positive selection due to their beneficial effects on the traits. CONCLUSIONS: The low correlation observed between FPed and genomic-based inbreeding estimates suggests that the presence of animals with one unknown parent (sire or dam) in the pedigree does not account for ancient inbreeding. The ROH hotspots surround genes related to reproduction, growth, meat quality, and adaptation to environmental stress. Inbreeding depression has adverse effects on productive and reproductive traits in Nelore cattle, particularly on age at puberty in young bulls and heifer calving at 30 months, as well as on scrotal circumference and body weight when scaled on the standard deviation of the trait.

Effects of in ovo vaccination time on broiler performance parameters under field conditions.

Hatchery performance is often evaluated based on descriptors such as hatchability, 7-d mortality, and cost. In addition to these descriptors, it is useful to include in this analysis aspects of chick quality through post-hatch performance. Realizing the bird's complete genetic potential necessitates meeting various criteria, with effective support for the chick's immune system being among the pivotal factors. To be effective, in ovo vaccination systems must deliver the vaccines to specific sites in the egg, a circumstance that directly depends on when the injection is made. We examined production data to evaluate the impact of in ovo vaccination time on performance parameters of male Ross308AP chicks. A comprehensive survey was conducted examining records from 3,722 broiler flocks produced and raised by the same company under standard nutrition and management conditions. The selected data specifically pertained to flocks that underwent slaughter between 41 and 45 d. In our analysis, 4 different linear models were built, one for each response variable: mean weight (MW), body weight gain (BWG), corrected feeding conversion rate (cFCR), and total mortality (TM). The linear models used in the analyses included as main predictor the timing of in ovo vaccination (440, 444, 448, 452, 456, 458, and 460 h of incubation), and as additional predictors: age of the breeding flock (26-35, 36-55 and 56-66 wks old), slaughter age, identity of the hatchery, and the season at which the data was collected. Our results showed that the timing of in ovo vaccination significantly affected BWG and cFCR, with procedures performed at 460 h of incubation showing the best outcomes. Breeding flock age affected all response variables, with older breeding flocks delivering increased MW, BWG and TM, and middle-aged flocks increased cFCR. Increasing slaughter age reduced BWG while MW, cFCR and TM were all increased. These data emphasize the benefits of performing in ovo vaccination as close as possible to 460 h of incubation to extract the best BWG and cFCR from Ross308AP male broiler.

Scarce Evidence of Heterosis for Growth Traits in Peruvian Guinea Pigs.

This study aimed to estimate the heterosis for productive traits in a two-way crossbreeding scheme. Four guinea pig lines were originally selected for the following traits: line P1 for the growth rate, P2 for the partial feed conversion rate, M1 for the growth rate of the litter at 10 days of age, and M2 for the litter size at birth. The comparison included 176 purebreds (P1: 46, P2: 43, M1: 54 and M2: 33) and 150 crosses (P1P2: 42, P2P1: 38, M1M2: 11 and M2M1: 59); body weights at birth, 10 days, weaning and 60 days of age were analyzed. A linear fixed-effect model was used, and heterosis was estimated as the difference between the average performance of the crossbred and pure-line animals. The pure line comparisons showed that P2 was lower than P1 for weight at 10 days and weaning weight, while all other comparisons between the paternal and maternal pure lines were not significant. The results indicated significant positive heterosis effects for both types of crosses, but only for birth weight: 3.7% for paternal crosses and 12.7% for maternal crosses. The heterosis estimates were mostly positive but not significant for all other traits. A reason for the low levels of heterosis could be that the lines are not very genetically differentiated. These results suggest that applying a two-way crossbreeding scheme within paternal and maternal guinea pig lines for meat production is not recommended due to the absence of heterosis for growth traits.

Effect of adding Spirulina platensis algae to small ruminant rations on productive, reproductive traits and some blood components

This experiment conducted using 20 Rahmani ewes at the last third of pregnancy in two equal groups. One group served as control, while the other group received Spirulina platensis(SP) at the rate of 0.5 gm 10 kg-1live body weight. The objective was to find out the effect of adding Spirulina platensisalgae to small ruminant rations on reproductive and productive traits and blood components of sheep. The experiments lasted for 120 days for both dams and their lambs after weaning. The findings proved that adding SP in ewes' diets had no effect on the average of live body weight change. Average milk yield was significantly (p <0.01) higher in the treatment group than the control. Lamb's birth weight and daily body gain of the treated group were significantly (p <0.01) higher than the control. Blood and serum picture profile of ewes were significantly higher when fed SP additive than the control.It could be concluded that the addition of SP to the ration of sheep positively preserved their health, productive and reproductive status as well as their lambs' growth rate. Also the additive improved the economic efficiency of treated animals by about 53.13%.(AU)

Genetic parameters in traits of productive importance in lines of Bombyx mori L.

In the textile industry, complex cocoon traits are closely related to silk production. The aim of the present study was to estimate genetic parameters of economic importance traits-cocoon length (CL), cocoon weight (CW) and shell weight (SW)-in three B. mori lines-Chinese (C6), Japanese (J7) and Indian (C. Nichi)-reared under different temperature and photoperiod conditions. For each of these lines, data were collected from several generations with a full-sibling family structure and variance-covariance component were obtained via restricted maximum likelihood (REML) estimates based on a bi-trait animal model analysed through the multiple-trait derivative-free restricted maximum likelihood (MTDFREML) software. Genetic parameters of the traits varied between the silkworm lines were evaluated. Heritabilities were highest in J7 line (0.71, 0.89 and 0.93 for CL, CW and SW, respectively) followed by C6 (0.48, 0.54 and 0.50 for CL, CW and SW, respectively) and C. Nichi (0.36, 0.43 and 0.40 for CL, CW and SW, respectively). Phenotypic correlations among these lines were positive, with values ranging between 0.36 and 0.767. Similarly, genetic correlations between the analysed silkworm lines were observed to be positive, with high values ranging from 0.86 to 0.94. The evidence for environmental correlation in these lines was found only between CW-SW traits with moderate to high values ranging from 0.600 to 0.940. The magnitude of heritability and genetic correlations implies that phenotypic variations of the CL, CW and SW traits depend mainly on genotypic variation within the J7, C6 and C. Nichi lines, and that simultaneous genetic gains are possible by implementing selection processes for any of the evaluated traits.

Genetic parameters of growth traits and carcass weight of New Zealand white rabbits in a tropical dry forest area.

OBJECTIVE: The objective of this study was to estimate the heritability (h 2), repeatability (r), and correlations (ryiyi ) in some traits of zootechnical interest in a population of New Zealand white rabbits of a tropical dry forest area. MATERIALS AND METHODS: Three mating groups were formed, each one of 1 male and 70 females. The traits evaluated were litter size at birth (LB), born alive (BA), born dead (BD), litter weight born alive (LW), litter weight at weaning (LWW), weaning weight (WW), slaughter weight (SW), and carcass weight (CW). Weaning took place at 42 days, and the fattening phase lasted 60 ± 3 days. A descriptive statistical study was carried out on the study variables. Paternal heritability was estimated ( h f 2 ) and maternal ( h m 2 ), repeatability, rabbit index IC, and Pearson's correlations (ryiyi ) between traits. The descriptive statistics showed high variation for the BD traits. RESULTS: The values of the productivity found were similar to those presented in studies around the world. h 2 presented magnitudes between low and medium. h f 2 ranged between 0.09 and 0.42 and between 0.11 and 0.45 for h m 2 . In general, the values of h m 2 were higher than the values of h f 2 . The r values for the traits LB, BA, LW, LWW, and SW presented low magnitude, while it was medium for WW and CW. From the values of r, IC was calculated for each of the rabbits, allowing their categorization, which will be used in future selection plans. ryiyi among the variables ranged from -0.01 to 0.860. They were generally positive and mostly not significant (p > 0.05); they took a magnitude from low to moderate, except for the correlation between LB and BA. CONCLUSION: The production of rabbits under tropical conditions is similar to other reports. The genetic parameters evaluated were medium-to-low, indicating a robust non-additive gene and/or environmental effect.

Highly effective dietary inclusion of laurel (Laurus nobilis) leaves on productive traits of broiler chickens

Laurel leaves characterized with interesting antioxidant effects, which have often used to improve the immunity with positive consequences on growth and performance This study was conducted to assess the effect of adding crushed laurel leaves to the diet on the productive traits of broiler chickens. A total of 180 broiler chickens, were randomly assigned to four dietary treatments, with a rate of 45 birds per treatment; each treatment consisted of three replicates. The first treatment, or control, was generated without adding laurel leaves to the diet, second, third, and fourth treatments were generated by adding laurel leaves with amounts of 1, 2, and 3 g kg-1 feed, respectively. Nine productive traits were evaluated in this study, including the average of live body weight, weight gain, feed consumption, feed conversion ratio, percentage of mortality, productive index, length of the villus, depth of crypts, and villus length/crypts length ratio. Results indicated that the addition of laurel leaves led to a significant improvement in all productive traits, signifying highly essential participation of laurel leaves to enhance growth and performance. In conclusion, it can be stated that adding 3 g kg-1 of crushed laurel leaves to the diet can improve the productive traits of broiler chickens.

Highly effective dietary inclusion of laurel (Laurus nobilis) leaves on productive traits of broiler chickens

Laurel leaves characterized with interesting antioxidant effects, which have often used to improve the immunity with positive consequences on growth and performance This study was conducted to assess the effect of adding crushed laurel leaves to the diet on the productive traits of broiler chickens. A total of 180 broiler chickens, were randomly assigned to four dietary treatments, with a rate of 45 birds per treatment; each treatment consisted of three replicates. The first treatment, or control, was generated without adding laurel leaves to the diet, second, third, and fourth treatments were generated by adding laurel leaves with amounts of 1, 2, and 3 g kg-1 feed, respectively. Nine productive traits were evaluated in this study, including the average of live body weight, weight gain, feed consumption, feed conversion ratio, percentage of mortality, productive index, length of the villus, depth of crypts, and villus length/crypts length ratio. Results indicated that the addition of laurel leaves led to a significant improvement in all productive traits, signifying highly essential participation of laurel leaves to enhance growth and performance. In conclusion, it can be stated that adding 3 g kg-1 of crushed laurel leaves to the diet can improve the productive traits of broiler chickens.(AU)

Heritability estimation and genetic correlations for mature weight, visual scores, and growth traits in Nellore cattle

This study was intended to estimate the genetic associations between growth traits and visual scores with possible changes in mature weight (MW) in 397,900 Nellore animals. A bi-character analysis was performed to estimate the (co)variances and genetic parameters for MW, which comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, and WM) and yearling (YC, YP, and YM), birth weight (BW), weight from birth to weaning (WG), weight from weaning to yearling (YG), and final index (FIND). The observed mean MW was 417.6±56.2 kg, and the direct genetic effect mean estimated heritability (h²a1) of MW was 0.45. Overall, the BW was 31.0±3.7 kg, and the estimated h² was 0.34. The heritability estimate of the maternal additive genetic component (h²m2) of BW was 0.07. We calculated the mean WG to be 144.1±26.3 and estimated the h²a2 as 0.18 and h²m2 as 0.07. The value for h²a YG (0.17) and YW (0.26) were also estimated. The heritability of the weaning WC (0.17), WP (0.19), and WM (0.17) and yearling YC (0.25), YP (0.27), and YM (0.25) were estimated using visual scores. The h²m values for weaning WC, WP, and WM (0.06) with visual scores were estimated. The genetic correlations between body weight (BoW) at YC and WC (0.62) were considered moderately high and positive. In addition, YP (0.18), YM (0.15), WP (0.13), and WM (0.14) were considered moderately low compared with MW. The genetic correlation between BW and FIND (0.38) was considered positive and moderate. The heritability estimation indicates that growth traits, visual scores, and weight of adult cows could be changed by selection. Cows that presented the highest h²a values for live weight responded rapidly to selection based on growth characteristics, visual scores, and FIND and might result in increased final MW.(AU)

Breeding goals and economic values for Nellore cattle in a full-cycle production system

The objective of this study was to develop a bio-economic model for the estimation of economic values of economically important traits in a full-cycle beef cattle production system. The bioeconomic model calculated economic values by simulating the impact of changes in the profit of the system consisting of a 1% increase in each trait of the breeding objective, while the other traits were kept constant. The bio-economic model was effective in estimating the sources of revenues and expenses of the production system. The estimated economic values were, in the order of importance for the full-cycle system, R$ 3.69 for male slaughter weight, R$ 3.63 for male weaning weight, R$ 3.58 for weaning rate, R$ 3.40 for female slaughter weight, R$ 2.30 for female weaning weight, and R$ 0.13 for mature cow weight. The results showed that all traits evaluated in the full-cycle system had positive economic impact, indicating that selection would increase profitability maximizing the expected response for the traits of the breeding goal.(AU)

Breeding goals and economic values for Nellore cattle in a full-cycle production system

The objective of this study was to develop a bio-economic model for the estimation of economic values of economically important traits in a full-cycle beef cattle production system. The bioeconomic model calculated economic values by simulating the impact of changes in the profit of the system consisting of a 1% increase in each trait of the breeding objective, while the other traits were kept constant. The bio-economic model was effective in estimating the sources of revenues and expenses of the production system. The estimated economic values were, in the order of importance for the full-cycle system, R$ 3.69 for male slaughter weight, R$ 3.63 for male weaning weight, R$ 3.58 for weaning rate, R$ 3.40 for female slaughter weight, R$ 2.30 for female weaning weight, and R$ 0.13 for mature cow weight. The results showed that all traits evaluated in the full-cycle system had positive economic impact, indicating that selection would increase profitability maximizing the expected response for the traits of the breeding goal.

Growth, mortality and susceptibility of oyster Crassostrea spp. to Perkinsus spp. infection during on growing in northeast Brazil / Crescimento, mortalidade e susceptibilidade de ostras Crassostrea spp. à infecção por Perkinsus spp. em cultivo no Nordeste do Brasil

Crassostrea rhizophorae and C. gasar oysters are cultivated in the northeast region. Perkinsus parasites infect bivalves, and their effects on oysters from tropical regions are poorly understood. This study evaluated the impact of Perkinsus infection on the productive traits of native oysters. Oysters were sampled bimonthly during 7 months, from July 2010 to February 2011, to evaluate growth rate, mortality and shell color patterns (white and dark-gray) (n = 500), and to determine the prevalence and intensity of Perkinsus (n = 152). Perkinsus and Crassostrea species were determined using molecular tools. Results showed that most dark-gray (90%, n = 20) and white (67%, n = 18) oysters were C. gasar and C. rhizophorae, respectively. Oysters showed a high growth rate and moderate cumulative mortality (44%). C. gasar oysters grew better and showed lower mortality and lower incidence of Perkinsus compared to C. rhizophorae. The mean prevalence of Perkinsus was moderate (48%), but the infection intensity was light (2.2). Perkinsosis affected very small oysters (19.4 mm). In conclusion, native oysters, especially C. gasar, have a great potential for culture, mortality is not associated with perkinsosis, and the shell color of oysters can be used to improve selection for spats with better performance.(AU)

Crassostrea rhizophorae e C. gasar são cultivadas na região Nordeste. Parasitas Perkinsus infectam bivalves e seus efeitos em ostras de regiões tropicais são pouco compreendidos. Este estudo avaliou o impacto da infecção por Perkinsus em parâmetros de produção de ostras nativas. Ostras foram coletadas bimestralmente durante 7 meses, de julho de 2010 a fevereiro de 2011, para avaliar crescimento, mortalidade e padrão de coloração da concha (branca e cinza-escura) (n = 500); além da presença e intensidade de Perkinsus (n = 152). Perkinsus e Crassostrea foram identificados por abordagem molecular. Os resultados mostraram que as ostras cinza-escuras (90%, n = 20) e brancas (67%, n = 18) eram C. gasar e C. rhizophorae, respectivamente. As ostras mostraram uma boa taxa de crescimento e mortalidade acumulada moderada (44%). C. gasar cresceu melhor com menor mortalidade e menor incidência de Perkinsus que C. rhizophorae. A prevalência média de Perkinsus foi moderada (48%), mas a intensidade de infecção foi leve (2,2). A perkinsiose afetou ostras pequenas (19,4 mm). Em conclusão, ostras nativas, especialmente C. gasar, têm grande potencial de produção; sem mortalidade associada à perkinsiose; e, a cor da concha pode ser usada para melhorar a seleção de sementes com melhor desempenho.(AU)

Growth, mortality and susceptibility of oyster Crassostrea spp. to Perkinsus spp. infection during on growing in northeast Brazil / Crescimento, mortalidade e susceptibilidade de ostras Crassostrea spp. à infecção por Perkinsus spp. em cultivo no Nordeste do Brasil

Abstract Crassostrea rhizophorae and C. gasar oysters are cultivated in the northeast region. Perkinsus parasites infect bivalves, and their effects on oysters from tropical regions are poorly understood. This study evaluated the impact of Perkinsus infection on the productive traits of native oysters. Oysters were sampled bimonthly during 7 months, from July 2010 to February 2011, to evaluate growth rate, mortality and shell color patterns (white and dark-gray) (n = 500), and to determine the prevalence and intensity of Perkinsus (n = 152). Perkinsus and Crassostrea species were determined using molecular tools. Results showed that most dark-gray (90%, n = 20) and white (67%, n = 18) oysters were C. gasar and C. rhizophorae, respectively. Oysters showed a high growth rate and moderate cumulative mortality (44%). C. gasar oysters grew better and showed lower mortality and lower incidence of Perkinsus compared to C. rhizophorae. The mean prevalence of Perkinsus was moderate (48%), but the infection intensity was light (2.2). Perkinsosis affected very small oysters (19.4 mm). In conclusion, native oysters, especially C. gasar, have a great potential for culture, mortality is not associated with perkinsosis, and the shell color of oysters can be used to improve selection for spats with better performance.

Resumo Crassostrea rhizophorae e C. gasar são cultivadas na região Nordeste. Parasitas Perkinsus infectam bivalves e seus efeitos em ostras de regiões tropicais são pouco compreendidos. Este estudo avaliou o impacto da infecção por Perkinsus em parâmetros de produção de ostras nativas. Ostras foram coletadas bimestralmente durante 7 meses, de julho de 2010 a fevereiro de 2011, para avaliar crescimento, mortalidade e padrão de coloração da concha (branca e cinza-escura) (n = 500); além da presença e intensidade de Perkinsus (n = 152). Perkinsus e Crassostrea foram identificados por abordagem molecular. Os resultados mostraram que as ostras cinza-escuras (90%, n = 20) e brancas (67%, n = 18) eram C. gasar e C. rhizophorae, respectivamente. As ostras mostraram uma boa taxa de crescimento e mortalidade acumulada moderada (44%). C. gasar cresceu melhor com menor mortalidade e menor incidência de Perkinsus que C. rhizophorae. A prevalência média de Perkinsus foi moderada (48%), mas a intensidade de infecção foi leve (2,2). A perkinsiose afetou ostras pequenas (19,4 mm). Em conclusão, ostras nativas, especialmente C. gasar, têm grande potencial de produção; sem mortalidade associada à perkinsiose; e, a cor da concha pode ser usada para melhorar a seleção de sementes com melhor desempenho.

Genetic trends for mature body weight, visual scores, and growth traits in Nellore cattle / Tendência genética para peso adulto, escores visuais e características de crescimento em bovinos de corte da raça Nelore

Mature weight (MW) of cows is related to the costs of their production. Usually, cows with moderate MW are more efficient in challenging environments, such as those available in the production systems in Brazil. In the present study, the selection index comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, WM) yearling (YC, YP and YM), scrotal circumference at yearling (SC), days to gain 160kg from birth to weaning (D160) and 240kg after weaning (D240). This are related to birth weight gain at weaning (WG) and from weaning to yearling (YG). The mature (MW) and birth weight (BW) traits were not considered in the selection index. The aim of this study was to estimate the values for the genetic trends (GT) of some important selection (MW) and economic traits (BW). A bi-character analysis of MW and other characteristics was performed to estimate the (co)variance components and genetic parameters. The GT results obtained for MW were null (0.0065% or 0.02718kg per year) in the period 1990-2007. The GT values were determined for BW (-0.0650% or -0.02017kg), WG (0.0758% or 0.0865kg), YG (0.1051% or 0.11377kg), and MW (0.0393% or 0.11276kg) per year. The visual score values (in score units) were also determined for GTat weaning [WC (0.2310%; 0.00707), WP (0.3624%; 0.3623%),aWM (0.01149; 0.01087)] yearling [YC (0.3256%; 0.00990), YP (0.4795%; 0.01496),YM (0.5041%; 0.01457)] per year. Index-based selection was effective to promote genetic progress in WG, WC, WP, WM, YG, YC, YP, and YM characteristics keeping BW and MW constant.

O peso adulto das vacas (PV) está relacionado com os custos de produção. Em geral, vacas com PV moderados são mais eficientes em ambientes desafiadores, como aqueles disponíveis nos sistemas de produção no Brasil. No presente estudo, o índice de seleção compreende as seguintes características: conformação, precocidade e musculatura nas fases da desmama (CD, PD e MD) e sobreano (CS, PS e MS), circunferência escrotal no sobreano (CE), dias para ganhar 160kg do nascimento até a desmama (D160) e 240kg pós-desmama (D240), que estão relacionadas com os ganhos de peso do nascimento à desmama (GD) e, da desmama ao sobreano (GS). As características PV e PN não foram consideradas no índice de seleção. O objetivo deste estudo foi estimar os valores das tendências genéticas (TG) das importantes características de seleção (PV) e econômicas (PN). Para estimar os componentes de (co)variâncias e os dados genéticos, foram realizadas análises bi-caracter de PV com as demais características. Os resultados de TG obtidos para PV foram nulos (0,0065% ou 0,02718kg por ano) no período de 1990 á 2007. Os valores de TG foram estimados para PN (-0,0650% ou -0,02017kg), GD (0,0758% ou 0,0865kg), GS (0,1051% ou 0,11377kg) e PF (0,0393% ou 0,11276kg) por ano. Os valores dos escores visuais (em unidades de escore) foram determinados para TG à desmama [CD (0,2310%; 0,00707), PD (0,3624%; 0,3623%) e MD (0,01149; 0,01087)] e sobreano [CS (0,3256%; 0,00990), PS (0,4795%; 0,01496) e MS (0,5041%; 0,01457)] ao ano. A seleção baseada no índice foi efetiva para promover o progresso genético nas características de GD, CD, PD, MD, GS, CS, PS e mantendo PN e PV constantes.

Genetic trends for mature body weight, visual scores, and growth traits in Nellore cattle / Tendência genética para peso adulto, escores visuais e características de crescimento em bovinos de corte da raça Nelore

Mature weight (MW) of cows is related to the costs of their production. Usually, cows with moderate MW are more efficient in challenging environments, such as those available in the production systems in Brazil. In the present study, the selection index comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, WM) yearling (YC, YP and YM), scrotal circumference at yearling (SC), days to gain 160kg from birth to weaning (D160) and 240kg after weaning (D240). This are related to birth weight gain at weaning (WG) and from weaning to yearling (YG). The mature (MW) and birth weight (BW) traits were not considered in the selection index. The aim of this study was to estimate the values for the genetic trends (GT) of some important selection (MW) and economic traits (BW). A bi-character analysis of MW and other characteristics was performed to estimate the (co)variance components and genetic parameters. The GT results obtained for MW were null (0.0065% or 0.02718kg per year) in the period 1990-2007. The GT values were determined for BW (-0.0650% or -0.02017kg), WG (0.0758% or 0.0865kg), YG (0.1051% or 0.11377kg), and MW (0.0393% or 0.11276kg) per year. The visual score values (in score units) were also determined for GTat weaning [WC (0.2310%; 0.00707), WP (0.3624%; 0.3623%),aWM (0.01149; 0.01087)] yearling [YC (0.3256%; 0.00990), YP (0.4795%; 0.01496),YM (0.5041%; 0.01457)] per year. Index-based selection was effective to promote genetic progress in WG, WC, WP, WM, YG, YC, YP, and YM characteristics keeping BW and MW constant. (AU)

O peso adulto das vacas (PV) está relacionado com os custos de produção. Em geral, vacas com PV moderados são mais eficientes em ambientes desafiadores, como aqueles disponíveis nos sistemas de produção no Brasil. No presente estudo, o índice de seleção compreende as seguintes características: conformação, precocidade e musculatura nas fases da desmama (CD, PD e MD) e sobreano (CS, PS e MS), circunferência escrotal no sobreano (CE), dias para ganhar 160kg do nascimento até a desmama (D160) e 240kg pós-desmama (D240), que estão relacionadas com os ganhos de peso do nascimento à desmama (GD) e, da desmama ao sobreano (GS). As características PV e PN não foram consideradas no índice de seleção. O objetivo deste estudo foi estimar os valores das tendências genéticas (TG) das importantes características de seleção (PV) e econômicas (PN). Para estimar os componentes de (co)variâncias e os dados genéticos, foram realizadas análises bi-caracter de PV com as demais características. Os resultados de TG obtidos para PV foram nulos (0,0065% ou 0,02718kg por ano) no período de 1990 á 2007. Os valores de TG foram estimados para PN (-0,0650% ou -0,02017kg), GD (0,0758% ou 0,0865kg), GS (0,1051% ou 0,11377kg) e PF (0,0393% ou 0,11276kg) por ano. Os valores dos escores visuais (em unidades de escore) foram determinados para TG à desmama [CD (0,2310%; 0,00707), PD (0,3624%; 0,3623%) e MD (0,01149; 0,01087)] e sobreano [CS (0,3256%; 0,00990), PS (0,4795%; 0,01496) e MS (0,5041%; 0,01457)] ao ano. A seleção baseada no índice foi efetiva para promover o progresso genético nas características de GD, CD, PD, MD, GS, CS, PS e mantendo PN e PV constantes. (AU)

Genetic trends for mature body weight, visual scores, and growth traits in Nellore cattle

ABSTRACT: Mature weight (MW) of cows is related to the costs of their production. Usually, cows with moderate MW are more efficient in challenging environments, such as those available in the production systems in Brazil. In the present study, the selection index comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, WM) yearling (YC, YP and YM), scrotal circumference at yearling (SC), days to gain 160kg from birth to weaning (D160) and 240kg after weaning (D240). This are related to birth weight gain at weaning (WG) and from weaning to yearling (YG). The mature (MW) and birth weight (BW) traits were not considered in the selection index. The aim of this study was to estimate the values for the genetic trends (GT) of some important selection (MW) and economic traits (BW). A bi-character analysis of MW and other characteristics was performed to estimate the (co)variance components and genetic parameters. The GT results obtained for MW were null (0.0065% or 0.02718kg per year) in the period 1990-2007. The GT values were determined for BW (-0.0650% or -0.02017kg), WG (0.0758% or 0.0865kg), YG (0.1051% or 0.11377kg), and MW (0.0393% or 0.11276kg) per year. The visual score values (in score units) were also determined for GTat weaning [WC (0.2310%; 0.00707), WP (0.3624%; 0.3623%),aWM (0.01149; 0.01087)] yearling [YC (0.3256%; 0.00990), YP (0.4795%; 0.01496),YM (0.5041%; 0.01457)] per year. Index-based selection was effective to promote genetic progress in WG, WC, WP, WM, YG, YC, YP, and YM characteristics keeping BW and MW constant.

RESUMO: O peso adulto das vacas (PV) está relacionado com os custos de produção. Em geral, vacas com PV moderados são mais eficientes em ambientes desafiadores, como aqueles disponíveis nos sistemas de produção no Brasil. No presente estudo, o índice de seleção compreende as seguintes características: conformação, precocidade e musculatura nas fases da desmama (CD, PD e MD) e sobreano (CS, PS e MS), circunferência escrotal no sobreano (CE), dias para ganhar 160kg do nascimento até a desmama (D160) e 240kg pós-desmama (D240), que estão relacionadas com os ganhos de peso do nascimento à desmama (GD) e, da desmama ao sobreano (GS). As características PV e PN não foram consideradas no índice de seleção. O objetivo deste estudo foi estimar os valores das tendências genéticas (TG) das importantes características de seleção (PV) e econômicas (PN). Para estimar os componentes de (co)variâncias e os dados genéticos, foram realizadas análises bi-caracter de PV com as demais características. Os resultados de TG obtidos para PV foram nulos (0,0065% ou 0,02718kg por ano) no período de 1990 á 2007. Os valores de TG foram estimados para PN (-0,0650% ou -0,02017kg), GD (0,0758% ou 0,0865kg), GS (0,1051% ou 0,11377kg) e PF (0,0393% ou 0,11276kg) por ano. Os valores dos escores visuais (em unidades de escore) foram determinados para TG à desmama [CD (0,2310%; 0,00707), PD (0,3624%; 0,3623%) e MD (0,01149; 0,01087)] e sobreano [CS (0,3256%; 0,00990), PS (0,4795%; 0,01496) e MS (0,5041%; 0,01457)] ao ano. A seleção baseada no índice foi efetiva para promover o progresso genético nas características de GD, CD, PD, MD, GS, CS, PS e mantendo PN e PV constantes.

Association between MUC1 gene polymorphism and expected progeny differences in Nelore cattle (Bos primigenius indicus).

MUC1 is a heavily glycosylated mammalian transmembrane protein expressed by mucosal secretory tissues for both protection against microbial infection and lubrication. An important characteristic of MUC1 is its variable number of tandem repeats (VNTR) containing several sites for O-glycosylation. VNTR length has been associated with many human diseases and with certain economically important traits in domestic ruminants. The aim of the present study was to correlate the length of MUC1 gene VNTR with expected progeny differences (EPDs) obtained for growth, fertility and carcass traits. Five alleles were identified, with alleles containing short VNTRs being more frequent than those with long, thereby demonstrating that Brazilian Nelore cattle are characterized by high frequencies in short MUC1 VNTRs. Statistical analyses revealed there to be no significant association between VNTR length and EPDs for weight at 120 days (W(120) ), scrotal circumference at 365 (SC (365) ) and 450 (SC (450) ) days, age at first calving (AFC), and rib eye area (REA).

Association between MUC1 gene polymorphism and expected progeny differences in Nelore cattle (Bos primigenius indicus)

MUC1 is a heavily glycosylated mammalian transmembrane protein expressed by mucosal secretory tissues for both protection against microbial infection and lubrication. An important characteristic of MUC1 is its variable number of tandem repeats (VNTR) containing several sites for O-glycosylation. VNTR length has been associated with many human diseases and with certain economically important traits in domestic ruminants. The aim of the present study was to correlate the length of MUC1 gene VNTR with expected progeny differences (EPDs) obtained for growth, fertility and carcass traits. Five alleles were identified, with alleles containing short VNTRs being more frequent than those with long, thereby demonstrating that Brazilian Nelore cattle are characterized by high frequencies in short MUC1 VNTRs. Statistical analyses revealed there to be no significant association between VNTR length and EPDs for weight at 120 days (W120), scrotal circumference at 365 (SC365) and 450 (SC450) days, age at first calving (AFC), and rib eye area (REA).

Evaluation of the productive and reproductive performance of females with different fractions of genes of european and zebu breeds in a dairy herd / Avaliação do desempenho produtivo e reprodutivo de fêmeas com diferentes frações de genes de raças européias e zebuínas em um rebanho leiteiro

Evaluation of the productive and reproductive performance of a dairy herd was carried out using animals distributed in six different genetic groups composed by European and Gir breeds. It was used 523 lactation from 229 cows that calving between years 1991 and 2003. The reproductive management of crossbred cows were reproduction controlled and artificial insemination during all year. It was analyzed the effect of genetic groups, year of calve and calving station. The traits used in analyses were age at first calving, calving interval, lactation length and total milk yield. There was effect of genetic group (P 0.01) for age to the first calving. The average of age to the first calve had been lower (P 0.01) for cows 1/2 and 3/4 of European genes. The calving interval of animals with 1/2 of zebu genes had been lower (P 0.05) then the animals with more than 15/16 of European genes. The total milk production was higher for genetic groups 1/2, 3/4, 7/8 and 15/16 then animals with less than 1/2 and 5/8 genes of European breed. The results were 2606, 2807, 2789, 2649 kg of milk yield for 1/2, 3/4, 7/8 and 15/16 compared to 1827 kg and 2368 kg of milk yield for animals with less than 1/2 and 5/8 genes of European breed, respectively. There was significant effect of station of calve (P 0.05) and age of the cow to calve (P 0.01) on total milk yield. The year of calve affec

A avaliação do desempenho produtivo e reprodutivo de um rebanho leiteiro com animais, distribuídos em seis grupos com diferentes frações de genes de raças de origem européia e da raça Gir foi realizada, utilizando-se 523 registros de produção de 229 vacas que pariram entre os anos de 1991 a 2003. O plantel foi manejado com monta controlada e inseminação artificial durante todo o ano, sendo analisados os efeitos de grupo genético, ano do parto e estação do parto. Foram avaliadas as características idade ao primeiro parto, intervalo de partos, duração da lactação e produção total de leite. Houve efeito de grupo genético (P 0,01) sobre a idade ao primeiro parto. A média da idade ao primeiro parto foi menor (P 0,01) para vacas 1/2 e 3/4 de genes de origem européia. O intervalo de partos de animais 1/2 de genes zebuínos foi menor (P 0,05) do que animais com mais que 15/16 de genes de origem européia. A produção total de leite foi maior para os grupos com 1/2, 3/4, 7/8 e 15/16 que para o grupo de animais com 5/8 ou menos que 1/2 de genes das raças européias. Os resultados foram 2606, 2807, 2789, 2649 kg de leite por lactação para as vacas 1/2, 3/4, 7/8 e 15/16 comparados com 1827 e 2368 kg de leite produzido pelas vacas menos de 1/2 e 5/8 de genes de raças européias, respectivamente. Houve efeito de estação do parto (P 0,05) e idade da vaca ao parto (P 0,01) sobre a pr

Evaluation of the productive and reproductive performance of females with different fractions of genes of european and zebu breeds in a dairy herd / Avaliação do desempenho produtivo e reprodutivo de fêmeas com diferentes frações de genes de raças européias e zebuínas em um rebanho leiteiro

Evaluation of the productive and reproductive performance of a dairy herd was carried out using animals distributed in six different genetic groups composed by European and Gir breeds. It was used 523 lactation from 229 cows that calving between years 1991 and 2003. The reproductive management of crossbred cows were reproduction controlled and artificial insemination during all year. It was analyzed the effect of genetic groups, year of calve and calving station. The traits used in analyses were age at first calving, calving interval, lactation length and total milk yield. There was effect of genetic group (P 0.01) for age to the first calving. The average of age to the first calve had been lower (P 0.01) for cows 1/2 and 3/4 of European genes. The calving interval of animals with 1/2 of zebu genes had been lower (P 0.05) then the animals with more than 15/16 of European genes. The total milk production was higher for genetic groups 1/2, 3/4, 7/8 and 15/16 then animals with less than 1/2 and 5/8 genes of European breed. The results were 2606, 2807, 2789, 2649 kg of milk yield for 1/2, 3/4, 7/8 and 15/16 compared to 1827 kg and 2368 kg of milk yield for animals with less than 1/2 and 5/8 genes of European breed, respectively. There was significant effect of station of calve (P 0.05) and age of the cow to calve (P 0.01) on total milk yield. The year of calve affec

A avaliação do desempenho produtivo e reprodutivo de um rebanho leiteiro com animais, distribuídos em seis grupos com diferentes frações de genes de raças de origem européia e da raça Gir foi realizada, utilizando-se 523 registros de produção de 229 vacas que pariram entre os anos de 1991 a 2003. O plantel foi manejado com monta controlada e inseminação artificial durante todo o ano, sendo analisados os efeitos de grupo genético, ano do parto e estação do parto. Foram avaliadas as características idade ao primeiro parto, intervalo de partos, duração da lactação e produção total de leite. Houve efeito de grupo genético (P 0,01) sobre a idade ao primeiro parto. A média da idade ao primeiro parto foi menor (P 0,01) para vacas 1/2 e 3/4 de genes de origem européia. O intervalo de partos de animais 1/2 de genes zebuínos foi menor (P 0,05) do que animais com mais que 15/16 de genes de origem européia. A produção total de leite foi maior para os grupos com 1/2, 3/4, 7/8 e 15/16 que para o grupo de animais com 5/8 ou menos que 1/2 de genes das raças européias. Os resultados foram 2606, 2807, 2789, 2649 kg de leite por lactação para as vacas 1/2, 3/4, 7/8 e 15/16 comparados com 1827 e 2368 kg de leite produzido pelas vacas menos de 1/2 e 5/8 de genes de raças européias, respectivamente. Houve efeito de estação do parto (P 0,05) e idade da vaca ao parto (P 0,01) sobre a pr