Arcadio de los Reyes Borjas

Bio: Arcadio de los Reyes Borjas is an academic researcher from Universidade Federal de Goiás. The author has contributed to research in topics: Purebred & Heritability. The author has an hindex of 6, co-authored 8 publications receiving 118 citations.

Prevalência e etiologia da mastite bovina no município de teresina, piauí

Abstract: The aim of present study was to verify the etiology and prevalence of bovine mastitis in the Terezina, city. A total of 852 quarters from cows during avery lactating pe¬riod raised on 8 dairy farms in Terezina, Piaui, were exa¬mined. Out of 346 (41.10%) positive cows by CMT (+, ++ e +++). A total of 252 (72.83%) were confirmed though bacteriological methods. From the agents isolated in pure or mixed cultures, the Staphylococcus was most frequen¬tly observed (74.60%). KEY-WORDS: CMT, epidemiology, milk, Piaui, Staphylococcus.

Breeding goals and selection criteria for intensive and semi-intensive dairy goat system in Brazil

Abstract: The aim of this study was to identify traits of socio-economic relevance for intensive and semi-intensive dairy goat production system, to derive economic weights for the breeding goals and to propose selection indices whose criteria are easily collected by dairy goat breeders. The economic value of each trait was calculated as the difference between the average profit before and after the improvement of criteria, after increasing each trait by 1%, keeping the average of other traits unchanged. Eight selection indices were proposed. Four indices (I–IV) were determined for the intensive system and four (V–VIII) for the semi-intensive system. The traits included in each index were: milk production (MP) and lactation length (LL) (I and V); MP, LL, and age at first kidding (AFC) (II and VI); MP, LL, AFC and kidding interval (CI) (III and VII); and MP, LL, AFC, CI, somatic cell count (SCC) and total solids (TS) (IV and VIII). The average profit of the semi-intensive system was higher than the intensive system, R$ 0.18 and R$ 0.14, respectively. The use of indices III and VI promoted simultaneous improvement in both productive and reproductive traits. With differential payment for better quality milk, TS and SCC levels, use of indices IV and VIII are indicated. The choice and use of these indices depend on the definition of objectives and of the measurement ease of selection criteria.

Parâmetros nutricionais do capim-tanzânia sob doses crescentes de nitrogênio em diferentes idades de corte

Abstract: The objective this experiment was to evaluate the chemical composition and in vitro dry matter digestibility of Tanzania grass under increasing nitrogen levels in different cutting ages, under irrigation. The treatments were three N levels (ammonium sulphate): 200, 400 and 600 kg.ha -1 for year and four cutting ages: 28; 56; 84 and 112 days. A randomized complete blocks design in factorial 3x4 arrangement (three N levels and four cutting ages, with three repetitions) was used. The analyses were accomplished using the sta-tistical System of Analysis of Variance of Data Balanced (SISVAR) program. The DM tenors didn’t differ (P 0.05) didn’t differ among the cutting ages, however they differed (P 0.05) among the cutting ages, except the 112 days, however, they differed among the N levels applied.KEY-WORDS: Chemical composition, in vitro dry matter digestibility, nitrogen fertilization.

Variabilidade genética do peso adulto de matrizes em um rebanho Nelore do Estado de São Paulo

Abstract: Records of 776 Nellore cows from a herd raised at Sao Paulo State, Brazil, were analyzed to determine the cow mature weight and to estimate their genetic and phenotypic parameters. A previous analysis showed that month and season of birth were not important sources of variation for the cow mature weight. This trait was influenced most by the month when the cows were weighted (April or July) and by the age of the cow (4 to 14 years, at the midpoints of the intervals). It was then used a linear mixed model that included the fixed effects of age of the cow and month of the weighing, combined in 22 classes, and the animal genetic additive effects. The average cow mature weight was 458 kg, varying from 330 through 585 kg, with a standard deviation of 39 kg and cows were in average 7.6 years old. The phenotypic, genetic and environmental variances were 1,544, 561, and 983 kg2, respectively, resulting on a heritability estimate of 0.36. The predicted genetic values for cow mature weight ranked from - 40.1 kg through + 44.4 kg, showing that success may be attained by including this new trait as an alternative selection criteria for the Brazilian Nellore genetic improvement programs.

Direct and correlated responses to selection for yearling weight on reproductive performance of Nelore cows.

Abstract: Data from a selection experiment for growth carried out in Brazil were analyzed in order to evaluate the direct responses on yearling weight (YW) and the correlated responses on the size and reproduction traits of cows. The experiment was started in 1976, and in 1980 three lines of Nelore cattle were established: selection (NeS), traditional (NeT), both selected for higher YW, and control (NeC), selected for mean YW. The NeT was an open line that eventually received bulls from other herds. Yearling weight records for animals born from 1978 to 1998 and yearling hip height (H550) offemales born from 1985 to 1998 were analyzed by fitting an animal model in order to obtain the genetic trends. The means for weight, height, and body condition score at the start of the breeding season, days to calving, and calving success of cows born from 1993 to 1996 (pertaining to the third to fourth generations of selection) were compared between the selected (NeS and NeT) and control lines. The genetic trends obtained after 16 yr for YW were 1.7 +/- 0.2, 2.3 +/- 0.2, and -0.1 +/- 0.1 kg/yr for males and 1.9 +/- 0.2, 2.4 +/- 0.2, and -0.1 +/- 0.1 kg/yr for females, for the NeS, NeT, and NeC lines, respectively. Corresponding values for H550 were 0.25 +/- 0.03, 0.24 +/- 0.04 and -0.04 +/- 0.03 cm/yr for females. Heifers and cows from NeS and NeT were 19% and 15% heavier and 4% taller at the start of the breeding season than those from NeC. No significant differences between selected (NeS and NeT) and control females were detected for body condition scores and for reproductive performance. The results indicate that selection for body weight promoted high and consistent weight and height responses both at the yearling and later ages, without compromising the reproductive performance of the cows with respect to days to calving and calving success.

Estimativas de (Co)variâncias entre características de reprodução e de crescimento em fêmeas de um rebanho Nelore

Abstract: Informations of 7986 births of animals from a Nellore cattle herd, from 1960 to 1993, were used to estimate (co) variance components, heritabilities and genetic correlations of weaning weight (W240), yearling weight (W365), age at first calving (AFC), first calving interval (CI1), reproductive efficiency (RE), longevity (LONG), calculated as years of permanence of cow in herd and weaning weight of the first calf of cow (W240C). The analysis were performed using the MTDFREML software, estimating the (co) variance components by restricted maximum likelihood, assuming an animal model. Estimates of heritability showed similar results among the different analyses, being higher (0.26 to 0.35) for W240, W365 and AFC and lower (0.08 to 0.26) for CI1, RE, LONG and W240C. In general, the estimates of genetic and phenotypic correlations among growth and reproductive traits were low and among the reproductive traits were high and favorable. Some correlations between maternal genetic effect of the growth and the direct genetic effect of the reproductive traits were of average magnitude and unfavorable, suggesting genetic antagonism between milk production and reproduction.

Comparison of different nonlinear functions to describe Nelore cattle growth

Abstract: This work aims to compare different nonlinear functions for describing the growth curves of Nelore females. The growth curve parameters, their (co)variance components, and environmental and genetic effects were estimated jointly through a Bayesian hierarchical model. In the first stage of the hierarchy, 4 nonlinear functions were compared: Brody, Von Bertalanffy, Gompertz, and logistic. The analyses were carried out using 3 different data sets to check goodness of fit while having animals with few records. Three different assumptions about SD of fitting errors were considered: constancy throughout the trajectory, linear increasing until 3 yr of age and constancy thereafter, and variation following the nonlinear function applied in the first stage of the hierarchy. Comparisons of the overall goodness of fit were based on Akaike information criterion, the Bayesian information criterion, and the deviance information criterion. Goodness of fit at different points of the growth curve was compared applying the Gelfand's check function. The posterior means of adult BW ranged from 531.78 to 586.89 kg. Greater estimates of adult BW were observed when the fitting error variance was considered constant along the trajectory. The models were not suitable to describe the SD of fitting errors at the beginning of the growth curve. All functions provided less accurate predictions at the beginning of growth, and predictions were more accurate after 48 mo of age. The prediction of adult BW using nonlinear functions can be accurate when growth curve parameters and their (co)variance components are estimated jointly. The hierarchical model used in the present study can be applied to the prediction of mature BW in herds in which a portion of the animals are culled before adult age. Gompertz, Von Bertalanffy, and Brody functions were adequate to establish mean growth patterns and to predict the adult BW of Nelore females. The Brody model was more accurate in predicting the birth weight of these animals and presented the best overall goodness of fit.

Estimativas de parâmetros genéticos para altura do posterior, peso e circunferência escrotal em bovinos da raça Nelore

Abstract: Visando estimar parâmetros geneticos em bovinos, foram utilizados registros de pesos padronizados aos 120, 210, 365, 450 e 550 dias de idade (P120, P210, P365, P450 e P550), altura do posterior mensurada proxima ao sobreano (ALT) e circunferencias escrotais (CE) padronizadas aos 365, 450 e 550 dias de idade (CE365, CE450 e CE550). Os dados foram provenientes de animais machos e femeas, nascidos entre 1998 e 2003 em dez fazendas de seis estados brasileiros. Os componentes de (co)variância foram estimados pela metodologia REML em analises uni, bi e trivariadas, utilizando-se modelos animal. As estimativas de herdabilidade do efeito direto com os respectivos erros-padrao foram: ALT 0,63 (0,09), P120 0,25 (0,03), P210 0,34 (0,03), P365 0,45 (0,04), P450 0,48 (0,04), P550 0,49 (0,04), CE365 0,48 (0,04), CE450 0,53 (0,04) e CE550 0,42 (0,09). As correlacoes geneticas entre a ALT e as variaveis P120, P210, P365, P450 e P550 foram de 0,68; 0,64; 0,53; 0,58 e 0,59, respectivamente. As associacoes geneticas do P120 com as CE ajustadas para peso e idade foram proximas de zero, entretanto, essas correlacoes foram positivas e moderadas, quando as CE foram ajustadas somente pela idade. As correlacoes geneticas da ALT com as CE, quando ajustadas para peso e idade, foram: -0,19 (CE365), -0,24 (CE450) e 0,00 (CE550). Utilizando um modelo que nao incluiu o peso do animal como covariavel, as correlacoes geneticas das CE com a ALT foram: 0,21 (CE365), 0,12 (CE450) e 0,39 (CE550). Essas estimativas indicam que as caracteristicas de crescimento e CE apresentam variabilidade genetica na raca Nelore, podendo ser incluidas em programas de melhoramento genetico, e a selecao para peso em qualquer idade deve acarretar aumento na estatura dos animais. Desta forma, para obtencao de animais com tamanho e peso adequados ao sistema de producao, faz-se necessaria a utilizacao de um indice de selecao aliando estas caracteristicas.

Herdabilidades e Correlações Genéticas para Peso e Perímetro Escrotal de Machos e Características Reprodutivas e de Crescimento de Fêmeas, na Raça Canchim

Abstract: The objective of this study was to estimate heritabilities of and genetic correlations among male body weight (BW12) and scrotal circumference (SC12) at 12 months of age, and female body weights at first (BWFC) and second (BWSC) calvings, age at first (AFC) and second (ASC) calvings, adult weight (AW), and mature weight (A) and maturation rate (k) obtained by the use of the Von Bertalanffy model. The restricted maximum likelihood method with an animal model that included the fixed effects of contemporary group and the random effects of animals, was used to estimate the variance and covariance components. The heritability estimates were equal to: 0.37 (BW12), 0.30 (SC12), 0.38 (A), 0.35 (k), 0.12 (AFC), 0.33 (BWFC), 0.04 (ASC), 0.39 (BWSC), and 0.38 (AW). The genetic correlations among BW12 and the female traits were: 0.19 (parameter A), 0.62 (parameter k), -0.58 (AFC), 0.69 (BWFC), -0.56 (ASC), 0.61 (BWSC), and 0.60 (AW). The genetic correlations among SC12 and the female traits were: -0.24 (A), 0.27 (k), -0.47 (AFC), 0.09 (BWFC), -0.67 (ASC), 0.07 (BWSC), and -0.17 (AW). These results indicate that male body weight and scrotal circumference and female weights (BWFC, BWSC and AW) and growth curve parameters A and k have enough additive genetic variation to respond to mass selection. Selection to increase male body weight at 12 months of age should result on favorable correlated changes in AFC, ASC and parameter k of females, but with increases in female body weights (BWFC, BWSC and AW). Selection to increase SC12 should result on desirable correlated responses in AFC, ASC and k, without any considerable change in female adult body weights.