Acessibilidade / Reportar erro
Revista Brasileira de Zootecnia, Volume: 42, Número: 4, Publicado: 2013
  • Genetic parameters of agronomic characters in Panicum maximum hybrids Forage Crops

    Braz, Thiago Gomes dos Santos; Fonseca, Dilermando Miranda da; Jank, Liana; Resende, Marcos Deon Vilela de; Martuscello, Janaina Azevedo; Simeão, Rosangela Maria

    Resumo em Inglês:

    This study was carried out with the objective of estimating the genetic parameters of agronomic traits in Panicum maximum hybrids. Genotypes obtained from the crosses between the sexual plants S10 and S12 and cultivars Tanzania and Mombasa were evaluated. The design was an incomplete blocks design with two replicates (clones) and 33 blocks. Each block was constituted by three lines or plots with nine plants each, which were evaluated in six harvests. All the characters presented low broad sense heritabilities for both the individual harvest and for the mean of harvests and a large difference between the heritability and the individual repeatability coefficient, which may be due to the high permanent environmental variance, mainly for forage dry matter and leaf dry matter. On the other hand, the percentage of leaves also presented low repeatability and permanent environmental variance. The genotypic coefficients of variation were high, except for leaf percentage, but they were also associated with high residual coefficients of variation. Both the broad sense heritabilities per harvest and for the mean of harvests were of moderate magnitude for the agronomic traits evaluated in hybrid individuals of P. maximum. On the other hand, there is variability for selection of important characters such as total and leaf dry matter yields and selection for leaf percentage needs a greater number of harvests to improve selection efficiency. The genotypes presented great variability for Bipolaris maydis leaf spot incidence and this character can be included in the P. maximum breeding program.
  • Structural characteristics and forage mass of Tifton 85 pastures managed under three post-grazing residual leaf areas Forage Crops

    Silva, Wilton Ladeira da; Galzerano, Leandro; Reis, Ricardo Andrade; Ruggieri, Ana Cláudia

    Resumo em Inglês:

    The experiment was carried out on Cynodon spp cv. Tifton 85 pastures grazed by sheep under rotational stocking, with the objective of evaluating the structural characteristics as well as the forage mass of the pastures subjected to three grazing intensities in successive cycles. Treatments were composed of three residual leaf area indices (rLAI; 2.4; 1.6 and 0.8), allocated in completely randomized blocks with seven replications, totaling 21 experimental units. Tiller population density, pasture height, leaf area index, forage morphological composition and pasture forage mass were evaluated. The rLAI modified the tiller population density, which increased linearly with decrease in the rLAI of the pastures. Dry masses of leaf blade, stem and dead material were inferior when the rLAI imposed were lower, which resulted in differentiated forage production among the treatments. Tifton 85 pastures grazed by sheep in rotational stocking under tropical conditions with different rLAI show a modified sward structure over successive grazing cycles, mainly by alteration in the height and LAI of the plants at pre-grazing and by light interception post-grazing, which change the tiller population density. The residual leaf area index of 1.6 is the most suitable for pasture management for being equivalent to the heights of entrance and exit of animals on and from paddocks of 33 and 19 cm, respectively, which avoid great accumulation of dead material and excessive stem elongation, in addition to ensuring tillering in the sward.
  • Metabolic, productive and reproductive responses to postpartum short-term supplementation in primiparous beef cows Breeding, Genetics And Reproduction

    Astessiano, Ana Laura; Pérez-Clariget, Raquel; Espasandín, Ana Carolina; López-Mazz, Carlos; Soca, Pablo; Carriquiry, Mariana

    Resumo em Inglês:

    The objective of this study was to evaluate the effect of a short-term supplementation with rice bran (2 kg/cows/day) on the endocrine and metabolic profiles and hepatic gene expression, associated with the reproductive response in beef cows in grazing conditions. Thirty-eight primiparous beef cows (Hereford, Angus and Hereford × Angus) were used in a randomized block design according to genotype, calving date and body condition score at calving (BCS). At 64±14 days postpartum (day 0 of the experiment), cows were assigned to two nutritional treatments: i) control, grazing native pastures (CON, n=19) and ii) supplemented (SUP, n = 19) for 21 days (days 1 to 21 of the experiment). Blood samples were collected at 0, 7 and 22 days and liver biopsies were obtained at day 22 to determine the abundance of mRNA of growth hormone receptor (GHR), insulin-like growth factor -I (IGF1), and its binding proteins -2 and -3 (IGFBP2 and IGFBP3), and insulin receptor (INSR) using SYBR-Green real-time RT-PCR with hypoxanthine phosphoribosyltransferase as endogenous control. Short-term supplementation with rice bran did not modify either cow BCS or BW, or calf BW or average daily gain. However, it decreased by 11 days the length of postpartum anestrus of primiparous cows in grazing conditions, associated with increased concentrations of glucose and insulin, and reduced hepatic expression of IGFBP2 mRNA at the end of the experimental period.
  • Use of orthogonal functions in random regression models in describing genetic variance in Nellore cattle Breeding, Genetics And Reproduction

    Silva, Thiago Bruno Ribeiro da; Araújo, Cláudio Vieira de; Bittencourt, Thereza Cristina Borio dos Santos Calmon de; Araújo, Simone Inoe; Lôbo, Raysildo Barbosa; Bezerra, Luiz Antônio Framartino; Silva, Delvan Alves da; Silva, Alessandra Alves da

    Resumo em Inglês:

    A total of 204,912 records of birth weights up to 550 days of age, of 24,890 Nellore cattle, offspring of 375 sires and 16,917 dams from five herds in the state of Mato Grosso, Brazil, were used in order to describe the variability of the weight development by random regression models. The model evaluated as the most suitable used the covariance function of fourth order to describe the variability of the effects of additive genetic, animal permanent environmental and maternal effects of third order to describe the maternal genetic effect, with four classes of residual variance. Heritability estimates ranged from 0.18 to 0.46 from the beginning of trajectory to 210 days of age, from 0.45 to 0.48 post-weaning to 365 days of age and from 0.47 to 0.57 at later ages. The values of additive genetic correlations for different ages showed higher estimates between the closest ages, while birth weight was not very related to the weights at older ages. The body weight performance of the animals has additive genetic variation to respond to selection.
  • Effect of including liquid vinasse in the diet of rabbits on growth performance Non Ruminants

    Oliveira, Maria Cristina de; Silva, Diones Montes da; Carvalho, Celiza de Almeida Faleiros e Rodrigues; Alves, Mirlley Ferreira; Dias, Daisa Mirelle Borges; Martins, Poliana Carneiro; Bonifácio, Nadielli Pereira; Souza Júnior, Marcos Aurélio Proto de

    Resumo em Inglês:

    The effects of liquid vinasse (LV) in the diet for growing rabbits on performance, carcass yield and intestinal morphometry were assessed. Eighty New Zealand white rabbits were used in a randomized block design with five treatments (LV inclusion at 0, 25, 50, 75 and 100 g/kg diet) and four replications. There was no effect of the treatment on final weight, daily weight gain, mortality rate and carcass yield characteristics. The daily intakes of feed, dry matter, crude protein and energy and feed conversion decreased linearly with increase in LV in the diet. Including LV affected the duodenum crypt depth and the ilium villus perimeter and height linearly and affected the duodenum villus perimeter, height and the absorption surfaces and ilium crypt depth and absorption surface quadratically. There was no effect of including LV on jejunum morphometry. Vinasse can be used to feed growing rabbits at up to 87.8 g per kilogram of diet.
  • Soybean meal or cotton by-products associated with urea as source of nitrogen in the diet of lactating goats Ruminants

    Alves, Aldivan Rodrigues; Medeiros, Ariosvaldo Nunes de; Oliveira, Juliana Silva de; Costa, Roberto Germano; Costa, Marcone Geraldo; Queiroga, Rita de Cássia Ramos do Egypto; Souza, Darklê Luiza de

    Resumo em Inglês:

    The objective of this study was to evaluate the influence of sources of nitrogen on the intake and digestibility of nutrients and production and chemical composition of goat milk. Soybean meal (SBM), soybean meal + urea (SBM+U), cottonseed meal + urea (CM+U), cottonseed cake + urea (CC+U) and whole cottonseed + urea (WC+U) were used, representing the different sources of nitrogen in the diet. Ten crossbred goats were used (Alpine + Saanen), weighing on average 47.90±1.94 kg of body weight at 30 days of lactation, distributed in a double Latin square (5 × 5) with five treatments and five periods. There was influence of the different sources of nitrogen on the intakes of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF) and non-fiber carbohydrates (NFC) of animals, with the lowest values found in most of the variables studied for animals that received CC+U and WC+U. There was an effect of diets on the DM, OM, CP and NFC digestibility coefficients. The diet with sole addition of SBM presented the best result regarding the amount of milk produced, followed by animals fed SBM+U and CM+U and values of 2.05 kg/day; 1.92 kg/day; 1.73 kg/day; 1.47 kg/day; and 1.24 kg/day of milk for diets with SBM, SBM+U, CM+U, CC+U and WC+U, respectively. Milk composition was also changed, and the diet with WC+U showed higher percentages: 0.1208 and 0.0041 percent, for total solids and fat, respectively. There was no difference in nitrogen balance between treatments. The use of SBM+U and CM+U did not compromise the milk performance and characteristics, but the use of CC+U and WC+U is indicated in periods of low milk production.
  • Animal performance and carcass characteristics of Nellore young bulls fed coated or uncoated urea slaughtered at different weights Ruminants

    Pazdiora, Raul Dirceu; Resende, Flávio Dutra de; Faria, Marcelo Henrique de; Siqueira, Gustavo Rezende; Almeida, Geraldo Benedito de Souza; Sampaio, Ricardo Linhares; Pacheco, Paulo Santana; Prietto, Murilo Sergio Rodrigues

    Resumo em Inglês:

    The objective of this study was to evaluate animal performance and carcass characteristics of 64 Nellore young bulls at 22 months of age finished in a feedlot and slaughtered at five body weights (350; 455; 485; 555 and 580 kg) fed diets containing coated or uncoated urea. The experimental design adopted was completely randomized, set in a 4 × 2 factorial arrangement, and for the variables assessed in the control animals, it was 5 × 2. No effect of interaction between slaughter weights and diets were observed, so the variables were analyzed separately, compared by polynomial contrasts and by the F test, respectively. The time animals remained in the feedlot to reach slaughter weights was 66, 88, 145 and 194 days. Average daily gain (ADG) showed quadratic behavior, with a maximum of 1.44 kg/day with animals of 491.7 kg. Dry matter intake (DMI) (kg/day) was similar in all the treatments, but it decreased linearly as body weight increased. The bionutritional efficiency worsened linearly as body weight rose. The elevation in slaughter weight resulted in linear decrease in the percentage of beef round and increase in forequarter. Backfat thickness and rib eye area of the longissimus increased linearly and the percentages of muscle and protein in the carcass reduced and those of fat and ether extract increased linearly as body weight increased. Average daily gain, DMI, feed efficiency and carcass characteristics were not affected by diets containing coated or uncoated urea. However, animals fed coated urea presenter better crude fiber and neutral detergent fiber intake.
  • Effect of frame size on performance and carcass traits of Santa Inês lambs finished in a feedlot Ruminants

    Souza Júnior, Edmilson Lúcio de; Sousa, Wandrick Hauss de; Pimenta Filho, Edgard Cavalcanti; Gonzaga Neto, Severino; Cartaxo, Felipe Queiroga; Cezar, Marcílio Fontes; Cunha, Maria das Graças Gomes; Pereira Filho, José Morais

    Resumo em Inglês:

    The objective of this study was to evaluate the performance, qualitative, morphometric and quantitative carcass traits of Santa Inês lambs of different frame sizes finished in a feedlot. Twenty 120-day-old intact lambs with a 25.0±3.1 kg average body weight at the beginning of the experiment were used. Lambs received a diet containing 17% crude protein and 2.70 Mcal/kg dry matter. Frame size influenced performance and tissue composition in the carcasses of the lambs. Lambs with large frame sizes showed better carcass conformation compared with those of medium-sized frames. Frame size was found to have a significant effect on rump perimeter. Large-framed lambs showed higher compactness on the carcass index and carcass dressing area compared with medium-framed lambs. The cuts of large-framed lambs weighed more than those of mediumframed lambs. However, no significant differences were found in dressing.
  • Turix, a dynamic mechanistic model for feed evaluation Ruminants

    Vargas-Villamil, Luis Manuel; Ku-Vera, Juan Carlos; Vargas-Villamil, Felipe; Medina-Peralta, Salvador; Avila-Vales, Eric José; Aranda-Ibañez, Emilio Manuel; Avendaño-Reyes, Leonel

    Resumo em Inglês:

    The objective of this study was to use the Turix model (a new mechanistic dynamic model that can be used for feed evaluation under tropical conditions), along with in situ and in vitro sugar cane experimental data from a previous study, to evaluate sugar cane kinetics through estimation of three parameters associated with ruminal bacterial growth: kM,SmL, the substrate uptake; kLM, the bacterial growth from intermediate metabolite; and Y VFAP,FS, the products related to volatile fatty acid yield. Values of these parameters for the whole sugar cane and its neutral detergent fiber (NDF) and acid detergent fiber (ADF) fractions were: a) kM, SmL, 16.20, 50.47 and 21.97 mL h-1 (mg M)-1 ; b) kLM, 96.00, 543.00 and 1,680.00 h-1 ; and, 1.02, 0.40 and 0.23 g g-1 , respectively. Results from the model adjustment showed a slow microbial substrate uptake c) Y VFAP, FS and a low biomass yield for whole sugar cane. The highest substrate uptake was obtained for NDF, while the highest biomass yield was obtained for ADF. The interrelation between the parameters kM, SmL showed to be important for biological and Y VFAP, FS description of microorganism growth and VFAP and biomass production.
  • Ammonia volatilization from surface application of organic residues and urea on Marandu palisadegrass Short Communication - Technical Note

    Vanin, Álisson; Menezes, June Faria Scherrer; Benites, Vinicius de Melo; Simon, Gustavo André

    Resumo em Inglês:

    The objective of this study was to measure ammonia volatilization from surface application of pig slurry, poultry litter, urea and no fertilization. An experiment was conducted in a randomized block design, in plots repeated over time, with four treatments and four replications. The fertilizers tested were: mineral fertilizer (70 kg ha-1 N, 100 kg ha-1 P2O5 and 30 kg ha-1 of K2O, as urea, triple superphosphate and potassium chloride, respectively), pig slurry (200 m³ ha-1 applied in November 2008 and 200 m³ ha-1 applied in April 2009) and poultry litter (10 t ha-1 applied in November 2008 and 10 t ha-1 applied in April 2009). Five evaluations were performed with 24-hour intervals. Foams were used with glycerin and sulfuric acid, internally fixed in PET bottles for collecting ammonia. After collected, the samples were sent to the laboratory to determine volatilized ammonia levels by the semi-micro Kjedahl distillation method. Fertilization with chicken litter had lower ammonia volatilization in relation to urea and pig slurry. Most of the ammonia volatilization from pig slurry occurred within 48 hours after application, totaling losses of 630 g kg-1 of a total of 8.25 kg ha-1 of volatilized ammonia. The biggest loss by ammonia volatilization was from fertilization with urea, totaling approximately 80 g kg-1 of N applied.
Sociedade Brasileira de Zootecnia Universidade Federal de Viçosa / Departamento de Zootecnia, 36570-900 Viçosa MG Brazil, Tel.: +55 31 3612-4602, +55 31 3612-4612 - Viçosa - MG - Brazil
E-mail: rbz@sbz.org.br