Abstract: High reproductive efficiency is essential to guarantee sustainable livestock production and a satisfactory economic return for the meat producer. Reproductive biotechnologies and animal breeding play an important role in the livestock economy. These two factors have a long- established relationship between reproductive performance and profitability; consequently, improving reproductive and genetic efficiency will increase profitability. In Brazil, the beef livestock farming is practiced in all states and ecosystems in the country. Regardless of the production system, it is characterized by the predominance of the use of pastures. So beef cattle production systems are very different, with variable results. Advances in reproductive biotechnologies and genetic evaluation in different biomes have enabled the development of production systems with better performance in beef cattle systems.
Background: Reactivity in livestock species has been assessed in relation to the behavioral reactions of animals, through restrained and non-restrained tests. Environmental and genetic parameters for reactivity traits have been reported for farm animals, as sheep, providing support for the possibility of direct selection. Despite evidences, there is little information on how genetic and environmental factors affect the expression of reactivity in sheep during and after weighing. Therefore, this study aimed to estimate the environmental and genetic effects of reactivity traits in Ile-de-France x Texel crossbred lambs. Materials, Methods & Results: Reactivity traits from 188 Ile-de-France x Texel cross lambs, aged between 28 and 110 days-old, were assessed in two situations: 1- During weighing: a. vocalization (VOC), b. movement (MOV), c. tension (TEN), d. exploratory behavior (EB) and e. ears posture (EP), and 2- After exiting the weighing crate, in a chute, through: a. gait speed (GS) and b. flight speed (FS) tests. For the study of environmental effects the model considered the fixed effects of month of assessment, sex and management group and as covariates, the linear effects of type of birth, age of dam and age of lamb. The (co)variance and genetic parameters were estimated using REML in univariate analysis and the direct additive genetic effect was considered in the model as a random effect. From all the environmental effects, month of assessment was statistically important over all the reactivity traits. Similarly, the effects of age of dam and age of lamb were significant for almost all variables. The estimates of heritability and repeatability for the behavioral variables ranged from low to moderate magnitudes, with high standard errors, for VOC: 0.19 ± 0.17 and 0.15 ± 0.05, MOV: 0.21 ± 0.07 and 0.065 ± 0.02, TEN: 0.27 ± 0.19 and 0.16 ± 0.13, EB: 0.16 ± 0.12 and 0.13 ± 0.03, EP: 0.23 ± 0.19 and 0.21 ± 0.15, GS: 0.22 ± 0.16 and 0.13 ± 0.11 and FS: 0.165 ± 0.13 and 0.11 ± 0.06, respectively, indicating low possibility of direct selection and lowly repeatable behavioral responses over time. Discussion: The results showed the significant influence of type of management on the majority of variables, fact that may be explained by different management systems to which the animals were subjected, in addition to the weaning effect. The absence of significant effect of sex on reactivity variables contradicts previous findings, in which males were found to be less reactive than females. Regarding the genetic parameters, few estimates of heritability for reactivity traits have been reported for sheep, mainly assessed in the arena test. Such results differ from those obtained in the present study which were lowly and moderately heritable, but with high standard errors, probably due to the small number of animals and the structure of the relationship matrix. The coefficients of repeatability for the evaluated traits during and after weighing were also low, thus measurements in the first evaluations were relatively poor predictors of the same behavioral responses on subsequent situations. Although a relatively small number of animals were used in the present study, it was possible to estimate genetic parameters for reactivity traits assessed during and after weighing. Thus, it is necessary to invest in selection, as reactivity has important influence on ease of handling and animal welfare.
The objective was to develop selection indexes for Nellore cattle raised in full-cycle production system in the Brazilian Pantanal.The resulting offspring are retained as replacements or sold at two years of age.Preliminary analyses explored effects of scale on economic values (EV).However, given the available data, these effects were very small.Presented herein are results from a simulated system consisting of 5,000 cows with all animals maintained on pasture as is typical in Pantanal.The EV were determined by approximating the partial derivatives of the profit function, changing one trait at a time, by one unit, while keeping the other traits constant.Traits in the breeding objective were mature cow weight, direct and maternal weaning weight, postweaning average daily gain, subcutaneous fat depth, longissimus muscle area, and stayability.Economic values were calculated on the basis of number of animals (per head), number of animal units, and arroba of carcasss weight.Regardless of the basis, maternal weaning weight and subcutaneous fat depth made negligible contributions to the breeding objective.Proportions of variation in the breeding objectives (per head, per animal unit, per arroba) explained by cow weight, direct weaning weight, postweaning average daily gain, stayability, and longissimus muscle area were: 13, 13, 17; 6, 1, 5; 3, 3, 4; 67, 67, 61; and 11, 17, 13, respectively.These indexes may aid Nellore breeders in their selection decisions, thus facilitating the genetic progress and increased productivity and profitability of Pantanal herds.
The aim of this study was to estimate the coefficients of heritability and genetic correlations among visual scores (conformation, CPW; precocity, PPW; musculature, MPW) and reproductive traits: age at first lambing (AFL) and scrotal circumference (SC) evaluated at 180 days of age in Suffolk lambs. In the statistical model only the additive genetic effect was considered as random effect. The heritability estimates by univariate analyses for CPW, PPW, MPW, AFL and SC were 0.08, 0.12, 0.09, 0.20 and 0.22, respectively. The genetic correlations among AFL and CPW, PPW, MPW were -0.26, 0.19, and 0.08, respectively. The genetic correlation among SC and CPW, PPW, MPW were, respectively, 0.54, 0.88 and 0.86, and between AFL and SC was 0.26. The direct selection for conformation, precocity and musculature at 180 days of age and age at first lambing will provide slow genetic progress due to low heritability estimates. It is possible to obtain genetic gain in sexual precocity through selection on scrotal circumference in Suffolk rams. The favorable genetic correlation among visual scores and SC and between CPW and AFL, indicated the possibility to gain in genetic progress for reproductive traits through indirect selection of the visual scores in Suffolk sheep.
Context Most Brazilian beef breeding programs perform selection for young bodyweight, which will inevitably increase mature weight due to the genetic correlation among weights at different ages. Aims The objective of the present study was to estimate genetic parameters for bodyweight from birth to maturity in Gir, Guzerat, Nelore and Caracu cows born between 1981 and 2014 at Centro APTA Bovinos de Corte, Instituto de Zootecnia, Sertãozinho, São Paulo, Brazil. Methods The model included the fixed effects of contemporary group (herd and year of birth), month of birth and previous reproductive status (calved = 1, or not calved = 0), the linear and quadratic effects of animal and cow age as covariates, and direct additive genetic, maternal genetic and maternal permanent environmental effects as random effects. The genetic parameters were estimated by univariate analysis of weights adjusted at birth, and at 120, 210, 378, 450 and 550 days of age, and annually from 2 to 10 years. In addition, multivariate analysis was performed considering weights at birth, and at 210 and 550 days, and at 5 years of age for all breeds. Key results For the different breeds, the heritability estimates ranged from 0.28 to 0.49 for birthweight, from 0.11 to 0.31 for weaning weight, from 0.25 to 0.43 for yearling weight, and from 0.25 to 0.69 for weights from 2 to 10 years of age. The genetic correlations were high and positive, indicating that selection at any age will affect weights at the other ages. Conclusions The results suggest the possibility of genetic progress for weights at different ages and the use of the young weights to monitor the mature weight of the animals. Implications As the trait most strongly correlated with mature weight was yearling weight, already used as the selection criteria for females in the breeding program of the Instituto de Zootecnia, selection indexes should be derived to keep the mature cow weight constant, since heavier cows could be undesirable for pasture-based Brazilian production systems.
ABSTRACT The objective was to develop selection indexes for Nellore cattle raised in full-cycle production system in the Brazilian Pantanal. The resulting offspring are retained as replacements or sold at two years of age. Preliminary analyses explored effects of scale on economic values (EV). However, given the available data, these effects were very small. Presented herein are results from a simulated system consisting of 5,000 cows with all animals maintained on pasture as is typical in Pantanal. The EV were determined by approximating the partial derivatives of the profit function, changing one trait at a time, by one unit, while keeping the other traits constant. Traits in the breeding objective were mature cow weight, direct and maternal weaning weight, postweaning average daily gain, subcutaneous fat depth, longissimus muscle area, and stayability. Economic values were calculated on the basis of number of animals (per head), number of animal units, and arroba of carcasss weight. Regardless of the basis, maternal weaning weight and subcutaneous fat depth made negligible contributions to the breeding objective. Proportions of variation in the breeding objectives (per head, per animal unit, per arroba) explained by cow weight, direct weaning weight, postweaning average daily gain, stayability, and longissimus muscle area were: 13, 13, 17; 6, 1, 5; 3, 3, 4; 67, 67, 61; and 11, 17, 13, respectively. These indexes may aid Nellore breeders in their selection decisions, thus facilitating the genetic progress and increased productivity and profitability of Pantanal herds.
ABSTRACT The objective of this study was to evaluate the spatial distribution of purebred Bos taurus taurus bovine breeds raised in Brazil in association with climatic, physical and socioeconomic variables. The breeds Aberdeen Angus, Ayrshire, Braford, Brangus, Charolais, Devon, Flemish, Hereford, Pinzgauer, Shorthorn and Simental were classified according to their aptitude (milk, meat or dual-purpose). They were spatialized according to their aptitude using state and municipal information. The milk breeds were found in the states of Rio Grande do Sul and Santa Catarina, while the dual-purpose breeds were found in Minas Gerais and Rio Grande do Sul states and the beef breeds were concentrated in the southern region. Only the Aberdeen Angus meat breed showed higher dispersion in other regions. Meat and dual-purpose breeds tended to be raised in regions with lower maximum temperature, average temperature, thermal amplitude and temperature-humidity index. Dual-purpose breeds were found in municipalities with high humidity and altitude, but with a low gross domestic product, little technical guidance received from cooperatives and the government, low control of diseases and parasites, as well as low use of pasture rotation systems. The spatial distribution of Brazilian bovine taurine breeds, regardless of aptitude, was related to climatic, physical and socioeconomic factors.
ABSTRACT The objective of this study was to evaluate the spatial distribution of purebred Bos taurus taurus bovine breeds raised in Brazil in association with climatic, physical and socioeconomic variables. The breeds Aberdeen Angus, Ayrshire, Braford, Brangus, Charolais, Devon, Flemish, Hereford, Pinzgauer, Shorthorn and Simental were classified according to their aptitude (milk, meat or dual-purpose). They were spatialized according to their aptitude using state and municipal information. The milk breeds were found in the states of Rio Grande do Sul and Santa Catarina, while the dual-purpose breeds were found in Minas Gerais and Rio Grande do Sul states and the beef breeds were concentrated in the southern region. Only the Aberdeen Angus meat breed showed higher dispersion in other regions. Meat and dual-purpose breeds tended to be raised in regions with lower maximum temperature, average temperature, thermal amplitude and temperature-humidity index. Dual-purpose breeds were found in municipalities with high humidity and altitude, but with a low gross domestic product, little technical guidance received from cooperatives and the government, low control of diseases and parasites, as well as low use of pasture rotation systems. The spatial distribution of Brazilian bovine taurine breeds, regardless of aptitude, was related to climatic, physical and socioeconomic factors.
'/%3e%3cpath id='l' d='M-26.25 0h52.5v-12h-40.5v-16h33v-12h-33v-11H25v-12h-51.25z'/%3e%3cpath id='k' d='M-31.5 0h12v-48l14 48h11l14-48V0h12v-70H14L0-22l-14-48h-17.5z'/%3e%3cpath id='b' fill-rule='evenodd' d='M0 0a31.5 35 0 0 0 0-70A31.5 35 0 0 0 0 0m0-13a18.5 22 0 0 0 0-44 18.5 22 0 0 0 0 44'/%3e%3cpath id='d' fill-rule='evenodd' d='M-31.5 0h13v-26h28a22 22 0 0 0 0-44h-40zm13-39h27a9 9 0 0 0 0-18h-27z'/%3e%3cpath id='n' d='M-15.75-22C-15.75-15-9-11.5 1-11.5s14.74-3.25 14.75-7.75c0-14.25-46.75-5.25-46.5-30.25C-30.5-71-6-70 3-70s26 4 25.75 21.25H13.5c0-7.5-7-10.25-15-10.25-7.75 0-13.25 1.25-13.25 8.5-.25 11.75 46.25 4 46.25 28.75C31.5-3.5 13.5 0 0 0c-11.5 0-31.55-4.5-31.5-22z'/%3e%3cuse xlink:href='%23a' id='o' transform='scale(31.5)'/%3e%3cuse xlink:href='%23a' id='p' transform='scale(26.25)'/%3e%3cuse xlink:href='%23a' id='r' transform='scale(21)'/%3e%3cuse xlink:href='%23a' id='q' transform='scale(15)'/%3e%3cuse xlink:href='%23a' id='s' transform='scale(10.5)'/%3e%3cg id='m'%3e%3cclipPath id='c'%3e%3cpath d='M-31.5 0v-70h63V0zM0-47v12h31.5v-12z'/%3e%3c/clipPath%3e%3cuse xlink:href='%23b' clip-path='url(%23c)'/%3e%3cpath d='M5-35h26.5v10H5z'/%3e%3cpath d='M21.5-35h10V0h-10z'/%3e%3c/g%3e%3cg id='h'%3e%3cuse xlink:href='%23d'/%3e%3cpath d='M28 0c0-10 0-32-15-32H-6c22 0 22 22 22 32'/%3e%3c/g%3e%3cg id='a' fill='%23fff'%3e%3cg id='f'%3e%3cpath id='e' d='M0-1v1h.5' transform='rotate(18 0 -1)'/%3e%3cuse xlink:href='%23e' transform='scale(-1 1)'/%3e%3c/g%3e%3cuse xlink:href='%23f' transform='rotate(72)'/%3e%3cuse xlink:href='%23f' transform='rotate(-72)'/%3e%3cuse xlink:href='%23f' transform='rotate(144)'/%3e%3cuse xlink:href='%23f' transform='rotate(216)'/%3e%3c/g%3e%3c/defs%3e%3crect width='100%25' height='100%25' x='-50%25' y='-50%25' fill='%23009b3a'/%3e%3cpath fill='%23fedf00' d='M-1743 0 0 1113 1743 0 0-1113z'/%3e%3ccircle r='735' fill='%23002776'/%3e%3cclipPath id='g'%3e%3ccircle r='735'/%3e%3c/clipPath%3e%3cpath fill='%23fff' d='M-2205 1470a1785 1785 0 0 1 3570 0h-105a1680 1680 0 1 0-3360 0z' clip-path='url(%23g)'/%3e%3cg fill='%23009b3a' transform='translate(-420 1470)'%3e%3cuse xlink:href='%23b' y='-1697.5' transform='rotate(-7)'/%3e%3cuse xlink:href='%23h' y='-1697.5' transform='rotate(-4)'/%3e%3cuse xlink:href='%23i' y='-1697.5' transform='rotate(-1)'/%3e%3cuse xlink:href='%23j' y='-1697.5' transform='rotate(2)'/%3e%3cuse xlink:href='%23k' y='-1697.5' transform='rotate(5)'/%3e%3cuse xlink:href='%23l' y='-1697.5' transform='rotate(9.75)'/%3e%3cuse xlink:href='%23d' y='-1697.5' transform='rotate(14.5)'/%3e%3cuse xlink:href='%23h' y='-1697.5' transform='rotate(17.5)'/%3e%3cuse xlink:href='%23b' y='-1697.5' transform='rotate(20.5)'/%3e%3cuse xlink:href='%23m' y='-1697.5' transform='rotate(23.5)'/%3e%3cuse xlink:href='%23h' y='-1697.5' transform='rotate(26.5)'/%3e%3cuse xlink:href='%23j' y='-1697.5' transform='rotate(29.5)'/%3e%3cuse xlink:href='%23n' y='-1697.5' transform='rotate(32.5)'/%3e%3cuse xlink:href='%23n' y='-1697.5' transform='rotate(35.5)'/%3e%3cuse xlink:href='%23b' y='-1697.5' transform='rotate(38.5)'/%3e%3c/g%3e%3cuse xlink:href='%23o' x='-600' y='-132'/%3e%3cuse xlink:href='%23o' x='-535' y='177'/%3e%3cuse xlink:href='%23p' x='-625' y='243'/%3e%3cuse xlink:href='%23q' x='-463' y='132'/%3e%3cuse xlink:href='%23p' x='-382' y='250'/%3e%3cuse xlink:href='%23r' x='-404' y='323'/%3e%3cuse xlink:href='%23o' x='228' y='-228'/%3e%3cuse xlink:href='%23o' x='515' y='258'/%3e%3cuse xlink:href='%23r' x='617' y='265'/%3e%3cuse xlink:href='%23p' x='545' y='323'/%3e%3cuse xlink:href='%23p' x='368' y='477'/%3e%3cuse xlink:href='%23r' x='367' y='551'/%3e%3cuse xlink:href='%23r' x='441' y='419'/%3e%3cuse xlink:href='%23p' x='500' y='382'/%3e%3cuse xlink:href='%23r' x='365' y='405'/%3e%3cuse xlink:href='%23p' x='-280' y='30'/%3e%3cuse xlink:href='%23r' x='200' y='-37'/%3e%3cuse xlink:href='%23o' y='330'/%3e%3cuse xlink:href='%23p' x='85' y='184'/%3e%3cuse xlink:href='%23p' y='118'/%3e%3cuse xlink:href='%23r' x='-74' y='184'/%3e%3cuse xlink:href='%23q' x='-37' y='235'/%3e%3cuse xlink:href='%23p' x='220' y='495'/%3e%3cuse xlink:href='%23r' x='283' y='430'/%3e%3cuse xlink:href='%23r' x='162' y='412'/%3e%3cuse xlink:href='%23o' x='-295' y='390'/%3e%3cuse xlink:href='%23s' y='575'/%3e%3c/svg%3e)