Random regression analyses using B-spline functions to model growth of Nellore cattle

The objective of this study was to estimate (co)variance components using random regression on B-spline functions to weight records obtained from birth to adulthood. A total of 82 064 weight records of 8145 females obtained from the data bank of the Nellore Breeding Program (PMGRN/Nellore Brazil) which started in 1987, were used. The models included direct additive and maternal genetic effects and animal and maternal permanent environmental effects as random. Contemporary group and dam age at calving (linear and quadratic effect) were included as fixed effects, and orthogonal Legendre polynomials of age (cubic regression) were considered as random covariate. The random effects were modeled using B-spline functions considering linear, quadratic and cubic polynomials for each individual segment. Residual variances were grouped in five age classes. Direct additive genetic and animal permanent environmental effects were modeled using up to seven knots (six segments). A single segment with two knots at the end points of the curve was used for the estimation of maternal genetic and maternal permanent environmental effects. A total of 15 models were studied, with the number of parameters ranging from 17 to 81. The models that used B-splines were compared with multi-trait analyses with nine weight traits and to a random regression model that used orthogonal Legendre polynomials. A model fitting quadratic B-splines, with four knots or three segments for direct additive genetic effect and animal permanent environmental effect and two knots for maternal additive genetic effect and maternal permanent environmental effect, was the most appropriate and parsimonious model to describe the covariance structure of the data. Selection for higher weight, such as at young ages, should be performed taking into account an increase in mature cow weight. Particularly, this is important in most of Nellore beef cattle production systems, where the cow herd is maintained on range conditions. There is limited modification of the growth curve of Nellore cattle with respect to the aim of selecting them for rapid growth at young ages while maintaining constant adult weight.

Genetic parameter estimates for live weight and daily live weight gain obtained for Nellore bulls in a test station using different models

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Resistance of cattle of various genetic groups to the tick Rhipicephalus microplus and the relationship with coat traits

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genetic correlations between heifer subsequent rebreeding and age at first calving and growth traits in Nellore cattle by Bayesian inference

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hydrogen production utilizing glycerol from renewable feedstocks-The case of Brazil

Various reports concerning catalytic reaction of glycerol for hydrogen production is available. However, economic analyses of this activity are not found yet. The objective of this work is to evaluate the process of hydrogen production via steam reforming of glycerol obtained through transesterification process of bio-oils. The thermochemical process of steam reforming process was determined due to high efficiency, feasibility and lower cost of design, development, operation and maintenance. These bio-oils come from feedstocks largely encountered in Brazil such as soybean, palm, castor bean, peanut and cotton seed as also come from residues such as defective coffee, tallow beef, wastewater (scum) and others. Various findings were obtained such as potential of production of glycerol utilizing residues (considering available amounts in the Brazilian states) and some vegetable feedstocks (considering production of harvested feedstock per hectare). Subsequently, production of hydrogen via steam reforming of generated glycerol, and foreseen electricity production via fuel cells were also determined. An additional estimation was paid for production of H-BIO, an innovative fuel developed by PETROBRAS (Petroleo Brasileiro S.A.), where hydrogen and bio-fuel are utilized and generates propane as co-product. About this work, it was concluded that high amounts of hydrogen and electricity could be produced considering an enormous potential from each cited feedstock being an attractive alternative as distributed electricity source and as an additional source for some activities, inclusively those that produce their own feedstocks such as abattoirs (beef tallow), and wastewater treatment plants. (C) 2010 Elsevier Ltd. All rights reserved.

Uso de produto à base de enzima e levedura na dieta de bovinos: digestibilidade dos nutrientes e desempenho em confinamento

Objetivou-se, com este trabalho, avaliar os efeitos da adição de diferentes níveis de enzima mais levedura na dieta de bovinos sobre a digestibilidade aparente dos nutrientes e o desempenho em confinamento, utilizando-se 18 animais machos, mestiços, de origem leiteira, com peso vivo (PV) médio de 190±10 kg e 12 meses de idade, e 27 animais da raça Guzerá com PV médio de 325 kg e idade média de 27 meses. Os níveis de enzima mais levedura foram zero (controle), 5 g de enzima (E) mais 5 g de levedura (L) e 10 g de E mais 5 g de L por animal por dia. Todos os animais receberam a mesma dieta, constituída de 65% de silagem (50% de milho:50% de sorgo) e 35% de concentrado composto de milho (24,6%), farelo de algodão (7,4%), uréia (1,2%), sal mineralizado (0,54%) e calcário (0,86%). Esta dieta apresentava 12,4% de PB; 10,1 MJEM/kg MS e 41,1% de FDN. A adição de enzima mais levedura não alterou o consumo de MS (3,31% do PV ou 126,6 g/kg PV0,75), e CDA da MS (63,0%), PB (68,2%), EE (83,3%), CHOT (61,3%), FDN (47,2%), FDA (43,8%) e valor de NDT (62,8%). O GMD e o CMS diminuíram de forma quadrática e a CA alimentar piorou linearmente, em função dos dias de confinamento. O fornecimento de enzima mais levedura para bovinos de corte não traz benefícios nutricionais ou de desempenho.

Características de carcaça e composição corporal de touros jovens da raça Nelore terminados em diferentes sistemas

O objetivo do trabalho foi avaliar comparativamente as características de carcaça e a composição corporal de machos jovens da raça Nelore não-castrados, filhos de touros com diferencial positivo (Linhagem Seleção) ou nulo (Linhagem Controle) para ganho de peso aos 378 dias de idade. Utilizaram-se informações de 92 zebuínos Nelore, com peso de abate médio de 456,00 kg, sendo 51 animais pertencentes à Linhagem Seleção e 41 animais da Linhagem Controle, foram criados em pastagens cultivadas até os 18 meses, quando foram alocados nos dois sistemas de terminação, de forma a compor grupos homogêneos quanto ao peso e filiação. Os animais de confinamento receberam, em baias individuais, ração para possibilitar ganhos de 1,0 kg/cab/dia. Antes do abate, os animais foram submetidos a jejum e pesados, quando se obteve o peso de abate. Após o armazenamento das carcaças em câmara fria, obteve-se a seção da 9ª-10ª-11ª costelas. Não houve efeito significativo de linhagem para nenhuma das características analisadas, exceto para a porcentagem de ossos, sendo que os animais da Linhagem Seleção superaram os animais da Linhagem Controle. O regime de terminação apresentou efeito significativo para a quase totalidade das características estudadas, com exceção para as características de composição corporal. Não houve efeito significativo de interação entre linhagem e terminação. As classes de idade apresentaram efeito significativo para as características peso de abate, peso de carcaça quente, peso da gordura renal-pélvica-ingüinal, porcentagem de músculo, gordura e osso.

Diarréia em bezerros da raça Nelore criados extensivamente: estudo clínico e etiológico

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Identification and characterization of polymorphisms within the 5' flanking region, first exon and part of first intron of bovine GH gene

The aim of the present study was to identify and characterize polymorphisms within the 5' flanking region, first exon and part of first intron of the bovine growth hormone gene among different beef cattle breeds: Nelore (n = 25), Simmental (n = 39), Simbrasil (n = 24), Simmental x Nelore (n = 30), Canchim x Nelore (n = 30) and Angus x Nelore (n = 30). Two DNA fragments (GH1, 464 bp and GH2, 453 bp) were amplified by polymerase chain reaction and then used for polymorphism identification by SSCP. Within the GH1 fragment, five polymorphisms were identified, corresponding to three different alleles: GH1.1, GH1.2 and GH1.3 (GenBank: AY662648, AY662649 and AY662650, respectively). These allele sequences were aligned and compared with bovine GH gene nucleotide sequence (GenBank: M57764 and AF118837), resulting in the identification of five insertion/deletions (INDELs) and five single nucleotide polymorphisms (SNPs). In the GH2 fragment two alleles were identified, GH2.1 and GH2.2 (GenBank: AY662651 and AY662652, respectively). The allele sequences were compared with GenBank sequences (M57764, AF007750 and AH009106) and three INDELs and four SNPs were identified. In conclusion, we were able to identify six new polymorphisms of the bovine GH gene (one INDEL and five SNPs), which can be used as molecular markers in genetic studies.

Comparison among three approaches for evaluation of sexual precocity in Nellore cattle

Restricted breeding seasons used in beef cattle produce censored data for reproduction traits measured in regard to these seasons. To analyze these data, adequate methods must be used. The objective of this paper was to compare three approaches aiming to evaluate sexual precocity in Nellore cattle. The final data set contained 6699 records of age at first conception (AFC14) (in days) and of heifer pregnancy (HP14) (binary) obtained from females exposed to the bulls for the first time at about 14 months of age. Records of females that did not calve in the following year after being exposed to a sire were considered censored (77.5% of total). The models used to obtain genetic parameters and expected progeny differences (EPDs) were a Weibull mixed and a censored linear model for AFC14 and threshold model for HP14. The mean heritabilities obtained were 0.76 and 0.44, respectively, for survival and censored linear models (for AFC14), and 0.58 for HP14. Ranking and Pearson correlations varied (in absolute values) from 0.54 to 0.99 (considering different percentages of sires selected), indicating moderate changes in the classification. Considering survival analysis as the best selection criterion (that would result in the best response to selection), it was observed that selection for HP14 would lead to a more significant decrease in selection response if compared with selection for AFC14 analysed by censored linear model, from which results were very similar to the survival analysis.

Growth curve of Nellore calves reared on natural pasture in the Pantanal

Weight-age and hip height-age relations of Nellore calves, from birth to 10 months old were fitted using a logistic model including sex and year of birth as fixed effects. Calves and their dams were reared on natural pasture using continuous grazing system. The crude protein content and total digestible nutrients were analyzed for pasture selected by the animals. The weights of the calves were adjusted to 205 days and 365 days. There were no significant effects of sex and birth year on the growth curve parameters, but there were significant effects of sex on hip height. The average weight (a parameter) at 10 months of age was 170 kg and the inflection point was observed at 93.5 days old. When weight-age and hip height-age curves were combined in the same graph, the intersection occurred at 142 days. The number of days to gain 160 kg from birth to 205 days of age (adjusted) and number of days to gain 240 kg from 205 days to slaughter was different between the birth years, which were probably due to the quality of the natural pastures. It is necessary to implement nutritional management strategies such as high quality pasture and/or feeding supplementation for calves once they reach three months of age.

Detection of Babesia bigemina in cattle of different genetic groups and in Rhipicephalus (Boophilus) microplus tick

Babesia bigemina infections were investigated in four genetic groups of beef cattle and in Rhipicephalus (Boophilus) microplus engorged female ticks. Blood samples and engorged female ticks were collected from 15 cows and 15 calves from each of the following genetic groups: Nelore, Angus x Nelore, Canchim x Nelore, and Simmental x Nelore. Microscopic examination of blood smears and tick hemolymph revealed that merozoites of B. bigemina (6/60) as well as kinetes of Babesia spp. (9/549) were only detected in samples (blood and ticks, respectively) originated from calves. PCR-based methods using primers for specific detection of B. bigemina revealed 100% infection in both calves and cows, regardless the genetic group. Tick infection was detected by nested-PCR amplifications showing that the frequency of B. bigemina was higher (P 0.01) in female ticks collected from calves (134/549) than in those collected from cows (52/553). The frequency of B. bigemina was similar in ticks collected from animals, either cows or calves, of the four genetic groups (P > 0.05). (C) 2008 Elsevier B.V. All rights reserved.

A snapshot of management practices and nutritional recommendations used by feedlot nutritionists in Brazil

Feedlot consulting nutritionists were invited to participate in a survey of feedlot nutritional and management practices in Brazil. Thirty-one nutritionists completed the survey on a Web site that was designed for collection of survey data. The survey consisted of 94 questions that included general information (n = 10); commodity information (n = 12); and questions about the use of coproducts (n = 5), roughage source and levels (n = 5), finishing diet adaptation methods (n = 7), supplements and micronutrients (n = 8), feed mixers (n = 6), feeding management (n = 3), cattle management and type of cattle fed (n = 16), formulation practices (n = 17), information resources used for nutritional recommendations (n = 2), and 2 additional questions. One final question addressed the primary challenges associated with applying nutritional recommendations in practice. The number of animals serviced yearly by each nutritionist averaged 121,682 (minimum = 2,000; maximum = 1,500,000; mode = 120,000; total = 3,163,750). Twenty-two respondents (71%) worked with feedlots that feed less than 5,000 animals/yr. Labor, along with availability and precision of equipment, seemed to be the main challenges for the nutritionists surveyed. Most of the nutritionists surveyed used TDN as the primary energy unit for formulation. More than 50% of the clients serviced by the 31 nutritionists did not manage feed bunks to control the quantity of feed offered per pen, and 36.6% fed cattle more than 4 times daily. The NRC (1996) and Journal of Animal Science were the most used sources of information by these nutritionists. Overall, general practices and nutritional recommendations provided by the 31 nutritionists surveyed were fairly consistent. Present data should aid in development of new research, future National Research Council models, and recommendations for Brazilian feeding systems in which Bos indicus cattle predominate.

Efeito da somatotropina na hipertrofia das fibras musculares esqueléticas e precocidade reprodutiva de novilhas Nelore

O trabalho objetivou avaliar o desempenho produtivo, precocidade sexual e hipertrofia das fibras musculares esqueléticas em resposta à aplicação de somatotropina bovina recombinante (rbST). Foram utilizadas 58 novilhas Nelore de sete meses de idade com peso vivo médio de 193 kg. O delineamento experimental foi inteiramente casualizado, em um esquema fatorial incompleto e dividido em duas fases experimentais. Na primeira fase, com duração de 150 dias, os animais foram divididos em dois grupos, de acordo com os níveis de rbST, 0 mg (controle) e 500 mg, a cada 28 dias. Na Fase II, os animais do grupo controle da Fase I foram divididos em 15 e 14 novilhas, que receberam 0 mg e 500 mg de rbST, respectivamente; os animais tratados com 500 mg na Fase I foram divididos em 15 e 14 novilhas e receberam 500 mg e 1.000 mg de rbST, respectivamente, com intervalos de 28 dias, e dieta em regime de pastejo, durante 180 dias. Foram retirados fragmentos do músculo semitendinosus para análise das fibras, no início e final da Fase I. Os animais foram pesados a cada 28 dias. Os resultados mostraram que não houve diferença significativa (p>0,05) entre os tratamentos quanto ao ganho de peso e quanto à precocidade sexual. Quanto ao diâmetro das fibras, os animais que receberam rbST tiveram um aumento significativo (p<0,01) tanto nas fibras de contração lenta quanto nas fibras de contração rápida em relação aos animais-controle.

Bovine gene polymorphisms related to fat deposition and meat tenderness

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)