José Carlos Vila Nova Alves Pereira

Bovinos mestiços alimentados com diferentes proporções de volumoso:concentrado. 1. Digestibilidade aparente dos nutrientes, ganho de peso e conversão alimentar

The objective of this work was to evaluate the effects of the forage to concentrate ratio on the weight gain and feed: gain, and to determine the apparent digestibility of the nutrients of 25 and 20 crossbred steers averaging 310 kg LW, respectively. Five full fed diets based on tanzaniagrass hay and concentrate, with different forage to concentrate ratio (85:15, 70:30, 55:45; 40:60; and 25:75) were used. The regression analysis of the coefficienties of apparent digestible dry matter, digestible organic matter, neutral detergent fiber, digestible protein and gross energy in function of the concentrate level in the diets presented quadratic effect and the maximum estimated coefficienties were 67.0, 70.0, 51.0 42.0 74.0 and 69.0 %, for the levels of 54, 58, 28, 12, 34 e 77 % of concentrate in the diets, respectively. The average daily gain (ADG) linearly increased with the increase of the concentrate level in the diets. There was an increase of 0.00895 kg/day in the ADG for each percent increase on the concentrate level in the diets, from 15.0 to 75.0 %. In the same range, the feed: gain of DM, CP, and GE increased 0.08; 0.011468; and 0,50646, respectively, for each percent increase on the concentrate level in the diets. The maximum nutrient digestion for the maximum efficiency of nutrient utilization occurred with the intake of neutral detergent fiber ranged from 1.25 to 1.02% LW for crossbred steers

Simulation of the nutrient dynamics in the gastrointestinal tract: application and validation of a mathematical model for grazing cattle

ABSTRACT - The objective of the present work was to validate the ruminal and post-ruminal nutrient dynamics and the ruminalmicrobial growth predictions, by using the equations of the Cornell system. The experiment was carried out during the rainy and dry seasonsof the 1996 year, in a natural pasture area situated in the county of Vicosa (MG). Esophageally, ruminally and abomasally cannulated steerswere used during two experimental periods within each season, and external markers (Cr 2 O 3 and Eu) were used to estimate the intake andthe ruminal digesta passage rate. The total nitrogen and the bacterial nitrogen flows, total and structural carbohydrates digested in the rumen,and the total of digestible nutrients contents were determined. These variables were also predicted from the model described in the Cornell system to validate its estimates. It was verified that the model was sensitive to the passage rate estimates, overestimated (12.38%) thebacterial nitrogen flow to the abomasum, and underestimated (70.64%) the structural carbohydrates availability in the rumen. The correctionbased on .02 h

Fractionation and in vitro degradation kinetics of extrusa nitrogenous compounds from grazing cattle

The objective of the present study was to determinate the nitrogenous compounds fractions present in the extrusa of grazing cattle maintained in a natural grassland in the Zona da Mata region, MG. The samples were obtained by using four esophageal fistulated steers in two experimental periods during the rainy season of 1996, and three of these animals were used to take samples in two experimental periods during the dry season of the same year. In order to obtain the nitrogen fractionation (fractions A, B 1 , B 2 , B 3 e C), the crude protein (CP), non-protein nitrogen (NPN), borate-phosphate buffer insoluble nitrogen, and neutral detergent and acid detergent insoluble nitrogen were determined. The in vitro degradation profiles of the protein fractions were obtained by incubating the pasture samples with Streptomyces griseus proteases. With these techniques it was possible to detect reductions in the CP content and in the percentage (% CP) of B 3 fraction and increases in the percentages of the A, B 1 and C fractions from EC to ES; no differences were found for the percentage of the fraction B 2 between seasons. The degradation rates of fractions B 2 and B 3 were extremely variable: its average estimates were 2.427 and 0.057 h -1 , respectively, during the rainy season, and 2.149 and 0.034 h -1 , during the dry season.

Avaliação final de clones IAC de cana-de-açúcar da série 1982, em latossolo roxo da região de Ribeirão Preto

ABSTRACTFIELD EVALUATION OF IAC SUGARCANE CLONES, AT THE RIBEIRAOPRETO REGION - STATE OF SAO PAULO, BRAZIL Twelve IAC sugar cane clones derived from crossings carried out in 1982, wereevaluated from 1990 to 1994, at three sites of the Ribeirao Preto/ region, in Rhodic Hapludoxsoils. Experimental trials were set up using a complete randomized blocks design, with sixreplications per site. Cane and sugar yield (t.ha -1 ), stalk sugar content, stalk fiber contentand stalk number were estimated in all four growing seasons. IAC82-2045 the clone signifi-cantly outperformed control varieties and other experimental clones regarding yield poten-tial, revealing intermediate sugar content and being proper for mid to late season harversting.Genetic parameter estimates have shown significant genotype x environment interactions,mostly for cane and sugar yield potentials.Index terms: sugarcane, improvement, breeding, interaction genotype-environment. 1. INTRODUCAOO melhoramento genetico da cana-de-acucar(Saccharum spp) tem inicio com a escolha dosparentais e obtencao de sementes pela hibridacao,mediante a qual se procura ampliar a variabilidadegenetica. A progenie obtida passa por sucessivas se-lecoes, nas quais se visa isolar os fenotipos desejadosque, levados a experimentacao em ensaios regionais,possibilita a indicacao de novas variedades comerciais.Desse modo, a obtencao de uma variedade de cana--de-acucar exige longo tempo, normalmente 12 a 15anos, desde a escolha dos parentais ate o plantio emescala comercial.O Instituto Agronomico (Campinas) vem man-tendo continuamente, desde 1947, um programa depesquisa (Segalla & Alvarez, 1968; Landell &Alvarez, 1993), que visa a ampliacao da variabilidadegenetica por meio de hibridacao. A partir de 1983, po-rem, optou-se por uma regionalizacao dos estudos, como intuito de observar a interacao genotipo-ambiente.Assim, ha na atualidade uma rede experimental abran-gendo seis regioes canavieiras paulistas (Landell etal., 1993). Dessa maneira, o programa possui a parti-cularidade de tentar identificar variedades com adap-tacao mais especifica as diferentes condicoes de soloe clima, alem de propiciar a obtencao de variedadesrusticas e longevas, que permitam manter os atuaisniveis de produtividade agroindustrial.Este trabalho teve por objetivo estudar, na regiaode Ribeirao Preto (SP), o comportamento de clonesIAC originarios de hibridacoes realizadas em 1982,quanto a parâmetros de produtividade agroindustrial,e avaliar as interacoes genotipo-ambiente.

Comportamento agronômico de linhagens de trigo no Estado de São Paulo

Eighteen wheat lines and the check cultivars IAC-24 and IAC-289 were evaluated in six trials carried out at different locations under dryland and sprinkler irrigation conditions, for grain yield, agronomic characteristics and disease resistance. In laboratory conditions, the germplasms were evaluated for their Al toxicity tolerance in nutrient solutions. The line L9 and the cultivar IAC-289 were superior in grain yield, considering the average of the six trials. The line L8 exhibited short stature associated to lodging resistance and early maturity. In relation to leaf rust the lines L1, L17 and L20 were resistant. All genotypes were susceptible to the causal agents of leaf spot and mildew. The line L7, showed long heads with the highest number of spikelets; IAC-289 and L17, the largest number of grain per head and per spikelet, respectively; and L11, the heaviest grains. All evaluated genotypes were tolerant to Al3+ toxicity, excepting the control cultivar Anahuac and the lines L15 and L20, which exhibited high sensibility.

Performance of milking cows fed concentrate at different levels associated or not with propolis

Two levels of concentrate (20 and 40% dry matter) and presence or absence of propolis ethanolic extract (PEE) in the diet at 30% w/v were evaluated in this study. The intake and apparent digestibility of nutrients, milk production and composition, live weight, feed efficiency and concentrate use for milk production were evaluated. Eight Holstein cows were distributed in two 4 × 4 Latin squares. The experiment was carried out in four 21-day periods, the first fourteen days were for the animals to adapt to the diets and the last seven days were for data collection. The experimental diets consisted of corn silage in the proportion of 80 or 60%, and concentrates based on corn and soybean meal, in addition to 34 mL PEE per day in the treatments that required this additive. The animals were housed in individual pens, fed ad libitum and milked twice a day. There was no interaction between concentrate levels and propolis, and there was no PEE effect for the evaluated parameters. The diets with 40% concentrate increased the daily dry matter, concentrate and TDN intakes, and caused reduction in forage intake in relation to diets with 20% concentrate. The total apparent digestibility coefficients did not change as a function of concentrate level in the ration. There was greater milk production, production of milk corrected to 3.5%, protein content and fat and protein production in milk in the diets with 40% concentrate. Although 40% concentrate diet allowed higher productive performance than 20% concentrate, the efficiency was only 0.68 kg milk/kg of concentrate. The addition of propolis does not alter the intake, digestibility and performance of cows producing above 20 kg of milk/day.

Influência da monensina no consumo e na fermentação ruminal em bovinos recebendo dietas com teores baixo e alto de proteína

Four ruminally fistulated Holstein steers were fed four times a day (8 a.m., 11 a.m., 2 p.m. and 5 p.m.) with four diets with low and high protein content, with or without monensin, to verify the effect of monensin on feed intake and ruminal fermentation. Diets contained (dry matter basis): low (11.4 %) and high (16.5%) crude protein content, 65% of brachiaria hay (Brachiaria decumbens) and 35% of concentrate. Corn and urea- and corn and soybean meal- based diets were, respectively, the concentrates of low and high protein content. The level of ionophore was of 28 mg of monensin/kg of DM intake. Samples of ruminal fluid were collected from the animals two hours post-feeding. The experiment was analyzed as a Latin square with four treatments and four animals. High protein content -based diets increased ruminal concentration of butyric acid and ammonia. Feeding of diets with monensin, independently of the protein content, decreased dry matter intake, increased propionic acid concentration and decreased butyric acid, acetate:propionate ratio and specific activity of ammonia production . Monensin with low protein content-based diet also decreased acetic acid concentration and incerased ruminal pH and microbial protein synthesis. No significant differences on the concentration of ruminal ammonia for diet with monensin were observed.

Adubação NK em três variedades de cana-de-açúcar em função de dois espaçamentos

Two factorial field experiments were carried out in the years of 1981 to 1984, in two soils (Dark-red Latosol - LE, and Dusky-red Latosol - LR) of the State of Sao Paulo, Brazil, with the objective of assessing the effect of N and K application on yield of three varieties of sugarcane grown in two row spacings. The fertilizer treatments for plant-cane consisted of the following combinations of N and K2O, in kg/ha: 0-210, 70-210, 140-210, 210-210, 140-0, 140-70, 140-140, and 140-210. All plots received equal amounts of P, at the rate of 120 kg P2O5/ha. The fertilizer treatments for 1st and 2nd ratoon were the same for all plots: 100, 30, and 120 kg/ha of N, P2O5, and K2O, respectively. Significant effects of row spacings, varieties, and NK application were observed on yields of cane and sucrose in both soils. Maximum calculated yields of cane were obtained with 165 kg N/ha and 148 kg K2O/ha in the LR soil, and 180 kg N/ha in the LE soil. The corresponding values for maximum sucrose yields were 153 kg N/ha and 104 kg K2O/ha in the LE soil and 128 kg K2O/ha in the LR soil. The highest rates of both N and K applied caused a decrease in the sucrose concentration of cane so that the rates of fertilizer application necessary for maximum sucrose yield were lower than those for maximum cane yield. The data for total cane and sucrose production (plant + ratoon) showed that the effects of N and K were similar to those obtained for plant-cane. The 1.2-meter row spacing produced higher yield of cane per unit area than that of the 1.5-meter spacing (increases of 14% in LR and 7% in LE, for plant + ratoon), and lower values per unit length of row (- 18% in LR and - 10% in LE). Varieties IAC58-480 and IAC64-257 showed greater sucrose yield than that of IAC52-150: 17% and 12% respectively in LR; in LE, both varieties produced 12% more than IAC52-150. Varieties also differed regarding sucrose content: IAC58-480 was 5% higher than IAC52-150 and the latter was 2% higher than IAC64-257.

Eficiência bioeconômica de estratégias de alimentação em sistemas de produção de leite: 1. Produção por animal e por área

This work was carried out to apply a simulation model for the bioeconomic evaluation of feeding strategies for dairy herds and evaluate the physical productivity and the bioeconomic efficiency of feeding systems for dairy cows using feeding forage based strategies for cows with five levels of milk yield. An computational platform developed with the programs CNCPS v5.0 and electronic spreadsheets of Microsoft Excell® was used, in way to simulate the production and demands of nutrients of a complete lactation for cows of different milk yield levels. Economic analyses in seven strategies of feeding were carried out. The income over feed costs (RMCA) showed interaction among the feeding strategy with the milk yield levels. The strategies based on corn silage during the dry season and pastures during rain season resulted in higher RMCA for all milk yield levels, although the other feeding strategies present closed results, depending on the milk yield level. In the evaluated strategies, as higher was the milk yield per cow, greater was the productivity (PROD/ha) and the RMCA per area (RMCA/ha). As higher was the carrying capacity of forages or the stoking rate, which determined area was submitted, considering determined feeding strategy and milk production level, higher was PROD/ha and the RMCA/ha. For RMCA per cow, forages of greater energy density result in decreased feeding costs and increase in the income per animal. The RMCA/ha was strongly influenced by the support capacity of the forages, in all milk yield levels.

Danos de percevejos e de lagartas em cultivares e linhagens de soja de ciclos médio e semi-tardio

The performance of soybean cultivars and lines belonging to two maturity groups (135-140 and 145-160 days of cycle) was evaluated during the 1995/96 and 1996/97 seasons in relation to damages caused by stink bugs and caterpillars in the field, at Ribeirao Preto, State of Sao Paulo, Brazil. Two experiments, one for each maturity group, were carried out, in each growing season, using a complete randomized block design. Infestation of Anticarsia gemmatalis Hub. occurred only in the first year. Stink bugs, Nezara viridula (L.), Euschistus heros (Fabr.) and predominantly Piezodorus guildinii (West.), occurred in both years with more severe infestation in the first year. The caterpillar defoliation was estimated by the percentage of eaten leaf area (PAFC). Three criteria were used to evaluate the damage caused by stink bugs: percentage of foliar retention (PRF), index of percent pod damage (IPDV) and yield. Based mainly in the first year, and regarding the earlier maturing genotypes, it can be considered that the line IAC 90-2971 presented resistance to caterpillars as well as to stink bugs similar to the line IAC 78-2318, the resistant control. In the experiment with the longer cycle genotypes, line IAC 93-2162 showed susceptibility to both caterpillars and stink bugs, in spite of presenting low PRF. The opposite occurred with line IAC 90-1970, with high PRF but low leaf injuries caused by ceterpillars, low IPDV and high yield. Besides the good performance of IAC 90-1970, the behavior of the cultivar IAC 9 and the line IAC 90-3052 could also be distinguished in relation to the low damages caused by stink bugs.