Repetibilidade da mensuração de imagens das características de carcaça obtidas por ultrassonografia em fêmeas Nelore

Avaliou-se a repetibilidade da mensuração de imagens de ultrassom da área do músculo longissimus dorsi (AOL) e das espessuras de gordura subcutânea do lombo (EGL) e da garupa (EGG). Imagens de ultrassom tomadas no lombo (entre a 12ª e a 13ª costela) e na garupa (entre os músculos gluteus medium e biceps femoris) de novilhas Nelore de 14 a 22 meses de idade foram classificadas em aceitáveis, marginais e rejeitáveis. As imagens aceitáveis e marginais foram mensuradas duas vezes por três técnicos em diferentes níveis de treinamento. Foram estimadas as repetibilidades entre e dentro de técnicos por classe de qualidade da imagem, para determinação do efeito da qualidade da imagem e do técnico no valor absoluto da diferença entre a primeira e a segunda mensuração dessas características. A repetibilidade para as imagens aceitáveis foi maior que para imagens marginais, tanto entre como dentro de técnicos. Na análise da diferença absoluta entre a primeira e a segunda interpretação, foram significativos os efeitos de técnico para AOL e EGL e de classe de qualidade da imagem para AOL. em geral, o técnico com maior experiência apresentou maiores valores de repetibilidade. É recomendável que a mensuração de imagens de animais de mesmo grupo contemporâneo seja feita por um único técnico.

Feed efficiency of Nellore cattle selected for postweaning weight

Foram comparados dois rebanhos Nelore, um selecionado para maior peso pós-desmame e outro controle, selecionado para a média de peso pós-desmame, para avaliar os efeitos de 29 anos de seleção sobre a eficiência alimentar. Sessenta machos Nelore com 205 kg e 267 dias de idade (41 selecionados e 19 controle), foram avaliados em baias individuais durante a prova de ganho de peso. O desempenho e o consumo de matéria seca foram utilizados para determinar as seguintes medidas de eficiência: conversão alimentar; consumo alimentar residual; ganho residual; eficiência parcial de crescimento; taxa de crescimento relativo; e taxa de Kleiber. Após o período experimental de 112 dias, os animais controle apresentaram menor peso vivo final em comparação aos selecionados, contudo, não diferiram quanto ao consumo de matéria seca (% do peso vivo), à área de olho-de-lombo e às espessuras de gordura subcutânea na altura da 12ª costela e na região da picanha. O consumo de matéria seca (kg/dia) e o ganho médio diário dos animais selecionados foram, respectivamente, 19,4 e 26,4% superiores aos dos controle. O maior ganho médio diário dos animais selecionados promoveu melhora significativa, em torno de 6%, na conversão alimentar; 70 g/dia no ganho residual; e de 17% na taxa de Kleiber. As demais medidas de eficiência (consumo alimentar residual, eficiência parcial de crescimento e taxa de crescimento relativo) não diferiram entre os rebanhos. Os 29 anos de seleção para peso pós-desmame não afetaram a eficiência alimentar de bovinos Nelore.

Test post-weaning duration for performance, feed intake and feed efficiency in Nellore cattle

O objetivo neste estudo foi determinar o melhor período de avaliação para medidas de desempenho, consumo e eficiência alimentar. Durante 112 dias, 60 machos da raça Nelore, recém-desmamados, submetidos à prova de ganho de peso, foram alimentados em baias individuais para determinação do consumo alimentar e do desempenho. O peso corporal dos animais foi determinado a cada 28 dias, depois de jejum de 16 horas de líquidos e sólidos. As alterações na variância, variância relativa e correlações de Pearson e Spearman entre os dados dos períodos de avaliação reduzidos (28, 56 e 84 dias) e período total (112 dias) foram usados para determinar a melhor duração do período de avaliação. A duração do período de avaliação para ganho médio diário, consumo de matéria seca, conversão alimentar e consumo alimentar residual pode ser reduzida para 84, 28, 84 e 84 dias, respectivamente, pois tal redução não diminui significativamente a confiabilidade das avaliações em animais alimentados em baias individuais.

Residual feed intake and relationships with performance of Nellore cattle selected for post weaning weight

Objetivou-se com este trabalho avaliar desempenho, parâmetros de eficiência e correlações fenotípicas entre medidas de eficiência energética de animais Nelore selecionados para peso pós-desmame e classificados quanto ao consumo alimentar residual, calculado pela diferença entre o consumo observado e o predito, com base no peso vivo médio metabólico e no ganho médio diário. Assim, os animais foram classificados em três grupos: alto (> média + 0,5 desvio-padrão; menos eficientes); médio (± 0,5 desvio-padrão da média); e baixo (< média - 0,5 desvio padrão; mais eficientes) consumo alimentar residual. Não foram observadas diferenças nos pesos vivos inicial e final, no ganho médio diário e no consumo de matéria seca entre os grupos. Animais com baixo consumo alimentar residual mostraram-se também com melhor eficiência alimentar, conversão alimentar e eficiência parcial de crescimento e não apresentaram diferenças em relação aos outros grupos quanto à taxa de crescimento relativo e taxa Kleiber. O consumo alimentar residual apresentou correlação significativa com eficiência alimentar (_0,25), conversão alimentar (0,25), eficiência parcial de crescimento (_0,37) e consumo de MS (0,16) e não apresentou correlação significativa com peso vivo (0,04), ganho médio diário (_0,02), taxa de crescimento relativo (_0,03) e taxa de Kleiber (_0,05). Foram encontradas correlações significativas entre conversão alimentar e peso vivo inicial (0,34) e ganho médio diário (_0,46). Eficiência parcial de crescimento apresentou correlação significativa comtodos os outros parâmetros de eficiência analisados. O consumo alimentar residual, em comparação às demais medidas de eficiência energética, apresenta grande potencial na eficiência produtiva, sendo independente de crescimento e tamanho dos animais.

Avaliação das Sub-Frações dos Carboidratos e das Proteinas, Usando as Metodologias do Cncps e In situ com Bovinos da Raça Nelore. 1. Silagem de Milho

To validate the use of the Cornell Net Carbohydrate and Protein System (CNCPS) under Brazilian conditions, the chemical composition, the potential and the effective degradabilities of the carbohydrate and protein subfractions, and the solid phase passage rate were determined for corn silage in diets with forage:concentrate ratios of 80:20 (DI) and 60:40 (D2) using Nellore cattle. The chromium mordant technique was used to determine the particulate passage rate of solids. For diet 2, there was a reduction in the potentially degradable dry matter (DM), and however not significant, a reduction in the degradation rates of neutral detergent Fiber (NDF, 49%) and neutral detergent insoluble nitrogen (NDIN, 32%), and an increase in the degradation rare of starch (ST, 25%). The use of lag time increased the effective DM degradation (EDDM) of corn silage in both diets (23% and 53% for D1 and D2, respectively). The concentrate ratios did not influence the particulate passage rate of the diets. The higher values related ro the availability of the protein subfractions may indicate a underestimation by CNCPS, Rnd(or) could be attributed to the Zebu animals used in this study.

Analysis of beef cattle longitudinal data applying a nonlinear model

The objective of this work was to evaluate the Nelore beef cattle, growth curve parameters using the Von Bertalanffy function in a nested Bayesian procedure that allowed estimation of the joint posterior distribution of growth curve parameters, their (co)variance components, and the environmental and additive genetic components affecting them. A hierarchical model was applied; each individual had a growth trajectory described by the nonlinear function, and each parameter of this function was considered to be affected by genetic and environmental effects that were described by an animal model. Random samples of the posterior distributions were drawn using Gibbs sampling and Metropolis-Hastings algorithms. The data set consisted of a total of 145,961 BW recorded from 15,386 animals. Even though the curve parameters were estimated for animals with few records, given that the information from related animals and the structure of systematic effects were considered in the curve fitting, all mature BW predicted were suitable. A large additive genetic variance for mature BW was observed. The parameter a of growth curves, which represents asymptotic adult BW, could be used as a selection criterion to control increases in adult BW when selecting for growth rate. The effect of maternal environment on growth was carried through to maturity and should be considered when evaluating adult BW. Other growth curve parameters showed small additive genetic and maternal effects. Mature BW and parameter k, related to the slope of the curve, presented a large, positive genetic correlation. The results indicated that selection for growth rate would increase adult BW without substantially changing the shape of the growth curve. Selection to change the slope of the growth curve without modifying adult BW would be inefficient because their genetic correlation is large. However, adult BW could be considered in a selection index with its corresponding economic weight to improve the overall efficiency of beef cattle production.

Condição imunológica de bovinos das raças Holandesa e Nelore frente a Babesia bovis e B. bigemina em duas regiões do Estado de São Paulo

The immunological reply of a population to an infectious agent can vary between races and handling of this population. Regional research becomes important, in order to know the interrelation between the agent and its host. In this way, the occurrence of immunoglobulins of class G, anti-Babesia bovis and anti-Babesia bigemina in the Nelore (Bos indicus) and Hostein breed (Bos taurus), was investigated in two regions of the State of São Paulo, 300 km distant from each other. For the indirect method of ELISA, 1, 161 bovine serum samples were tested. The medium frequencies of antibodies showed that in the two regions exists an enzootic stability for B. bovis in both breeds studied; even so there was a tendency of marginal area for the Nelore breed in one of the regions. Regarding B. bigemina, in both regions exists enzootic stability for the Hostein and enzootic instability for the Nelore breed. Therefore, acute cases of the disease or specific outbreaks by B. bigemina infection in the Nelore breed may occur in these regions.

Efeito da ovariectomia em novilhas Nelore x Angus, Bos taurus indicus x Bos taurus taurus sobre os ganhos de peso

This study aimed to evaluate the weight gain in cross breed heifers Nelore X Angus, spayed and nonspayed, kept on pasture and confinement. The animals were allotted in two groups as follows: group I consisted of 30 nonspayed heifers with 18 months old. Group 2 was composed of 30 spayed heifers with 18 months old. The animals were allotted in pasture of Brachiaria decumbens and weighted at 39 and 75 days. Significant difference was observed between the average daily gain of the two groups - G1 and G2 (75(th) day), respectively (0.51 kg and 0.65 kg; P<0.0 1). The following day (761 day), all animals were allotted and kept on confinement during 144 days. Significant difference was observed between the average daily gain of the two groups - G I and G2 (1441 day), respectively (0.73 kg and 0.58 kg; P<0.0 1). The results of this experiment show that spayed heifers presented a higher daily gain on pasture.

Avaliação das Sub-Frações dos Carboidratos e das Proteínas, Usando as Metodologias do Cncps e In situ com Bovinos da Raça Nelore. 2. Milho e Farelo de Algodão

The chemical composition of corn and cottonseed meal was determined in accordance with the Cornell Net Carbohydrate and Protein System (CNCPS) in diets with forage:concentrate ratios of 80:20 (D1) and 60:40(D2) using Nellore cattle. The potential and effective degradabilities of the carbohydrate and protein subfractions were also determined. For corn. diet 2 resulted in an increase for potentially degradable dry matter (DM). An increase was observed in the effective degradation of DM (EDDM) when lag time was not considered, however, the use of Eng time increased the EDDM for both diets, 23 and 18% for DI and D2. respectively. For cottonseed meal, diet 2 determined a reduction in the potentially degradable DM: therefore, the use of lag time increased the EDDM for bath diets, 14% for D1 and 15% for D2. The availability of corn starch (fraction B1) was lower than that determined by CNCPS. The higher values for the degradability of corn and cottonseed meal protein subfractions may indicate an underestimation by the model, and, or, could be attributed to the Zebu animals used in this study.

Heritability estimate for stayability in nelore cows

The objective of the present study was to determine the possibility of using stayability (STAY) of dams as a selection criterion for fertility in the Nelore breed. STAY was defined as whether or not a cow calved in a herd at a specific age or after this age given that she had calved at an earlier age. The specific ages studied were 5 (STAY5), 6 (STAY6) and 7 (STAY7) years. Data on 53 271, 46 011 and 41517 animals were analyzed for the respective ages. The Method 91 was used to estimate the variance components and a maximum threshold a posteriori model was used to predict the genetic values. The analyses provided h(2) estimates of 0.117+/-0.003, 0.122+/-0.004 and 0.171+/-0.005 for STAY5, STAY6 and STAY7, respectively. The ease with which the trait can be recorded and the h 2 estimates indicate that the use of this trait as a selection criterion can contribute to increased dam fertility. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Morphological characterization of follicle deviation in Nelore (Bos indicus) heifers and cows

Follicle diameter deviation is defined as the beginning of the differential change in growth rates between the largest and next largest follicles subsequent to wave emergence and is considered a key component of follicle selection. Follicle selection has been extensively studied in European breeds of cattle (Bos taurus) but has not been critically studied in Zebu breeds (Bos indicus). The objectives of the present study were to determine and compare the morphological characteristics of deviation associated with the first post-ovulatory wave (Wave 1) of the estrous cycle in Nelore heifers (n = 8) and nonlactating cows (n = 11). Beginning on the day of ovulation (day 0), the three largest follicles (F1-F3, respectively) were individually tracked every 12 h for 6 d using transrectal ultrasonography. In individual animals, deviation was determined graphically using visual inspection of the diameter profiles of F1, F2 and sometimes F3 (observed deviation) and mathematically using segmented regression analysis of the diameter differences between F1 and F2 or sometimes F3 (calculated deviation). Mean day of emergence of Wave 1 when F1 reached >3 rum (approximately 1 d after ovulation) and growth rate of F1 during deviation (approximately 1.4 mm/d) were not significantly different between heifers and cows. The results of determining the beginning of deviation within heifers and cows using the observed and calculated methods were not significantly different. Averaged over both methods, diameter deviation occurred 2.8 d after ovulation when F1 reached 5.7 mm in heifers, and 2.4 d after ovulation when F1 reached 6.1 mm in cows. In conclusion, the emergence of Wave 1 and growth rates and diameters of the future dominant follicles at the beginning of deviation were similar in Nelore heifers and nonlactating cows, regardless of the methods used to determine deviation. Relative to Holstein cattle, emergence of Wave 1 appeared to occur about 1 d later and diameter of the future dominant follicle at the beginning of deviation was about 2 turn smaller in Nelore. (C) 2004 Elsevier B.V. All rights reserved.

Fertility-associated proteins in Nelore bull sperm membranes

The present study was undertaken to evaluate the protein composition of the sperm membranes (SM) of Nelore bulls, assessing protein markers associated with bull fertility, and whether these markers can be used for predicting bull fertility. Samples were obtained of 20 Nelore bulls, with fertility ranked and divided into three groups (greater, normal and least). To rank the bull's fertility weighted classification was used (according to the number of pregnant cows, number of AI cows and number of herds, considering three different breeding seasons), using the PROC GENMOD as a statistical model, with 99% significance. A total of 7897 Nelore cows, randomly distributed among 28 different farms, were considered in the statistical analyses. The bulls were divided into three fertility groups (pregnancy rates): greater (%F > 80), normal (79 <%F > 71) and least (< 68%F) with 3, 13 and 4 bulls, respectively. Two-dimensional gel electrophoresis (2DE) of sperm membranes indicated in 27 spots (SM40, SM53, SM69, SM93, SM102, SM111, SM137, SM138, SM189, SM196, SM201, SM202, SM204, SM225, SM236, SM237, SM239, SM241, SM246, SM247, SM275, SM283, SM342, SM346, SM355, SM372, SM391) was prevalent in the higher fertility group, and just one spot (SM244) was prevalent in the lower fertility group. Spots SM244 and SM239 had their identification defined by PMF/MALDI-MS, as BSP-A3 and aSFP, respectively. Both these proteins showed a great potential for predicting bull's fertility. The amount of aSFP was 8.5 times greater in the sperm membrane protein profile of the higher fertility groups of Nelore bulls. Besides that, the BSP-A3 was 2.5 times greater in the lower fertility group. For the other spots potentially associated with fertility not yet identified, additional tests will be necessary, but it is clear that the 2D electrophoresis of the sperm membrane can be used for a new approach to predict Nelore bull fertility. (c) 2005 Elsevier B.V. All rights reserved.

Lead poisoning in cattle grazing pasture contaminated by industrial waste

Lead poisoning is described in a herd of 120 Nelore cows of which 35 were affected. All affected cows died after a clinical course of 2-7 d with clinical signs related to cortical neurological disturbances. The source of Pb was fumes from a car battery recycling plant which has had a failure in its filtering system. Lead concentrations in liver and kidneys of 2 cows, in soil;and in grass where the cows were held were respective 39 to 431 ppm, 147 to 431 ppm,and 245ppm. No significant gross changes were observed. Histopathology revealed of neuronal necrosis, vacuolation of the neuropil and hypertrophy of the vascular endothelium inthecerebral cortices, degeneration of the epithelial cellsofrenal proximal tubules, and hemosiderosis of kidney, spleen and liver.

Comparison of embryo yield and pregnancy rate between in vivo and in vitro methods in the same Nelore (Bos indicus) donor cows

To investigate why the preferred means to produce bovine embryos in Brazil has changed from in vivo to in vitro, we compared these two approaches in the same Nelore cows (n = 30) and assessed total embryo production and pregnancy rates. Without a specific schedule, all cows were subjected to ultrasound-guided ovum pick up (OPU)/in vitro production (IVP) and MOET, with intervals ranging from 15 to 45 d between procedures, respectively. To produce in vivo embryos, cows were superovulated and embryos were recovered nonsurgically from 1 to 3 times (1.4 +/- 0.6). whereas OPU/IVP was repeated from 1 to 5 times (3.2 +/- 1.2) in each donor cow during a 12-mo interval. Embryos obtained from both methods were transferred to crossbred heifers. on average. 25.6 +/- 15.3 immature oocytes were collected per OPU attempt. The average number of embryos produced by OPU/IVP (9.4 +/- 5.3) was higher (P < 0.05) than the MOET method (6.7 +/- 3.7). However, pregnancy rates were lower (P < 0.05) following transfer of IVP (33.5%) versus in vivo-derived embryos (41.5%) embryos. Embryonic losses between Days 30 and 60 and fetal sex ratio were similar (P > 0.05) between in vivo and in vitro-derived embryos. We concluded that in Nelore cows, with an interval of 15 d between OPU procedures, it was possible to produce more embryos and pregnancies compared to conventional MOET. (C) 2009 Elsevier B.V. All rights reserved.