RESUMO -Objetivou-se avaliar o valor nutritivo de três espécies forrageiras tropicais: capim-tanzânia (Panicum maximum Jacq.), capim-marandu (Brachiaria brizantha) e capim-tifton 85 (Cynodon spp), em duas épocas do ano (janeiromarço e abril-junho) e em três idades de rebrota (28, 35 e 42 dias), por meio da composição química, do fracionamento de proteínas e carboidratos e da digestibilidade in vitro da matéria seca (DIVMS) e da matéria orgânica (DIVMO). O capim-marandu destacou-se no período de janeiro-março, com menores conteúdos de parede celular e fração B2 dos carboidratos e maiores valores de proteína bruta, fração A + B1, DIVMS e DIVMO, em comparação aos capins tanzânia e tifton 85, independentemente da idade de corte. O aumento da concentração de parede celular em detrimento ao conteúdo celular com o avanço da maturidade das plantas foi evidente no capim-marandu no período de janeiro-março, quando foram observados maior valor da fração B2, maior conteúdo de fibra em detergente neutro (FDN) e menor concentração da fração carboidratos não-fibrosos. No período de abril-junho, a composição em parede celular não apresentou diferenças evidentes com aumento da idade, devido às condições ambientais observadas. O capim-tanzânia apresenta, de modo geral, baixos valores de parede celular e altos valores de carboidratos não-fibrosos, DIVMS e DIVMO nesse período, seguido pelos capins marandu e tifton 85, respectivamente.Palavras-chave: capim-marandu, capim-tanzânia, capim-tifton 85, conteúdo celular, parede celular, valor nutritivo Chemical composition, fractionation of carbohydrates and crude protein and in vitro digestibility on tropical forages in the different cutting ages ABSTRACT -This trial was conducted with the objective of evaluating the nutritive value of three tropical forage species: tanzania grass (Panicum maximum Jacq.), marandu grass (Brachiaria brizantha) and Tifton 85 bermudagrass (Cynodon spp) in two different periods of the year (January-March and April-June) and in three cutting ages (28, 35 and 42 days), based on the chemical composition, protein and carbohydrate fractions, and in vitro digestibility of dry matter (DMD) and organic matter (OMD). Marandu grass, in the period January-March, had the lowest cellular wall contents and B2 fraction of carbohydrates, and higher values of crude protein, A + B1 fraction, DMD and OMD in comparison to tanzania grass and Tifton 85 bermudagrass, regardless of the cutting age. The increase of concentration of the cell wall in detriment to the cell content as plant maturity advanced was evident in marandu grass during January-March when higher values of B2 fraction, higher content of neutral detergent fiber and lower concentrations of non fibrous carbohydrate fractions were observed. In April-June period, the cellular wall contents did not show evident differences as age increased due to environmental conditions. The tanzania grass presents, in general, lower values of the cell wall and higher values of non fibrous carbohydrate, DMD and OMD during this period, f...
-The objective of this study was to evaluate the mobilization of nutrients in goats of different gestation types and pregnancy stages. Forty-four Saanen and Oberhasli goats were studied. The goats of each breed and gestation type (single or twin) were slaughtered at different gestational ages (80, 110, and 140 days of pregnancy), forming a completely randomized design in a 2 × 3 × 2 factorial arrangement (two breeds, three gestational ages, and two types of pregnancy). The slaughter procedure involved separating the empty body, mammary glands, uterus with membranes and fetal fluid, and fetus(es). For the females slaughtered at 140 days of pregnancy, blood was collected to analyze metabolites and hormones every 15 days during gestation. The dry matter (DM) intake was lower in goats with twin pregnancies. The relative daily retention rate of the nutrients in the body was positive at 100 days of pregnancy but became negative at 140 days (-0.18±0.25 g DM kg -1 of maternal body d -1) and did not differ with breed or number of fetuses. Fetal growth in twin pregnancies was 66% higher than in single pregnancies. The highest levels of ß-hydroxybutyrate and non-esterified fatty acids were observed beginning at 100 days of gestation. Serum total protein and albumin levels decreased after 125 days of gestation. Serum urea levels were reduced after 80 days of gestation. Plasma 17ß-estradiol levels increased with the advance of pregnancy, and IGF-1 was highest between 60 and 80 days of gestation. The maternal metabolism throughout pregnancy does not vary with the type of pregnancy, and pregnant goats need greater nutritional intake during the final third of the gestational period regardless of the breed or type of pregnancy.
The aim of this study was to investigate the effect of different dietary levels of concentrate on feed intake, digestibility, ruminal fermentation and microbial population in steers. Eight Nellore steers fitted with ruminal cannulas were used in a double 4 × 4 Latin square design experiment. The dietary treatments consist of four different proportions of concentrate to roughage: 30:70, 40:60, 60:40 and 80:20% in the dry matter, resulting in Diets 30, 40, 60 and 80, respectively. The roughage was corn silage, and the concentrate was composed of corn, soybean meal and urea. Apparent digestibility of organic matter and crude protein showed a linear association with concentrate proportion (p = 0.01), but the increased concentrate levels did not affect the digestibility of fibre. The lowest ruminal pH-values were observed in animals fed with Diet 80, remaining below pH 6.0 from 6 h after feeding, while in the other diets, the ruminal pH was below 6.0 not before 12 h after feeding. After feeding Diet 80, the ammonia concentration in the rumen was significantly the highest. Higher dietary concentrate levels resulted in a linear increase of propionic acid concentrations, a linear reduction of the ratio acetic acid to propionic acid (p < 0.01) and a linear increased synthesis of microbial nitrogen (p < 0.001). The predicted production of methane was lower in diets with greater amounts of concentrate (p = 0.032). The population of methanogens, R. flavefaciens and R. albus decreased with higher concentrate levels, while the population of S. ruminantium increased (p < 0.05). The results indicate that greater amounts of concentrate do not decrease ruminal pH-values as much as expected and inhibit some cellulolytic bacteria without impairing the dry matter intake and fibre digestibility in Nellore steers.
During pregnancy, the maternal body undergoes significant physiological changes. The present study assessed the changes on calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na) and potassium (K) metabolism in singleton and twin-pregnant dairy goats. The 42 goats used (49.5 kg±7.6 body weight [BW]) were assigned at random to treatments that were factorially arranged to account for 2 breeds (Oberhasli and Saanen), 2 pregnancy types (singleton and twin) and 3 gestation periods (80, 110, and 140 days). Digestibility trials were performed at 80, 110, and 140 days of gestation. Mineral retention during pregnancy was determined in the maternal body, femur, uterus, mammary gland, fetus and fetal fluid. Blood samples were taken during pregnancy before and after a meal, and Ca, P, Mg, Na, K ions and alkaline phosphatase activity determined in serum. Bone mineral density was determined in the right femur. Statistical analyses were performed using the SAS MIXED procedure. Dry matter intake decreased linearly up to 140 days of gestation. Maternal BW gain, and Ca, P, and Mg retention (g/kg) decreased linearly with the advance of gestation days. Macromineral retention in maternal body (g/kg) was greater in Oberhasli than Saanen goats, and their fetuses had higher Ca, P, and Mg deposition (mg/g). Mineral retention (mg/g) increased in fetuses according to pregnancy development, with no differences between singleton and twin pregnancy. In the mammary gland, the retention of all minerals (g) increased with the days of pregnancy. In conclusion, related to Ca, P, and Mg metabolism can be divided into two stages. Up to 80 days of gestation, was characterized by the preparation of the maternal body reserves for future mineral demands. From 80 days of gestation onward, was characterized by the transfer of maternal body reserves for fetal development and colostrum production. Na and K supply was provided by adjustments in endogenous excretion and an increase in intestinal absorption. Finally, mineral metabolism was specific to each genotype and, except for Na, was not affected by the number of fetuses.
RESUMO -Avaliaram-se a cinética de fermentação e taxas de degradação de três espécies forrageiras tropicais (capins tanzânia, marandu e tifton 85), com três idades de corte (28, 35 e 42 dias) nos períodos de janeiro-março e abril-junho, mediante o uso da técnica de produção de gases in vitro. No período de janeiro-março, o capim-marandu apresentou os maiores valores de fração solúvel, degradabilidade potencial e degradabilidade efetiva a taxa de passagem de 2%/hora. No período de abril-junho, os capins marandu e tanzânia apresentaram resultados semelhantes para essas mesmas variáveis. Independentemente do período, o capim-tifton 85 apresentou os menores valores de fração solúvel, degradabilidade potencial e degradabilidade efetiva a 2%/hora e valores superiores de fração não-degradável. Em abril-junho, a idade de corte influenciou a fração solúvel e a produção de gases após 96 horas de incubação, cujos menores valores foram observados, de modo geral, aos 28 dias. As menores taxas de fermentação foram observadas para o capim-tifton 85 no período de abril-junho, independentemente da idade de corte.Palavras-chave: capim-marandu, capim-tanzânia, capim-tifton 85, degradabilidade efetiva, degradabilidade potencial, fermentação Fermentation kinetic and degradation rates of tropical forages harvested in different ages evaluated by in vitro gas production technique ABSTRACT -Fermentation kinetics and degradation rates of three tropical forage species (Tanzania grass, Marandu grass and Tifton 85 grass) were evaluated by the in vitro gas production technique. The forages were harvested at 28, 35 and 42 days of regrowth during two periods, January-March and April-June. In the January-March period, Marandu grass presented the greatest values of fraction A, potential degradability (PD) and effective degradability for a passage rate of 2 %/hour (ED2).In the April-June period, Marandu and Tanzania grasses presented similar results for the variables tested above. In both periods, Tifton 85 had the lowest values of fraction A, PD and ED2, and the greatest value of fraction C. In the April-June period, there was an age effect in relation to gas production potential and 96 hours of incubation with the lowest value was found for 28 days of regrowth. The lowest fermentation rates were observed in general for Tifton 85 grass in the April-June period, regardless of the regrowth age.Key Words: effective degradability, fermentation, marandu grass, potential degradability, tanzania grass, tifton 85 bermudagrass IntroduçãoA técnica de produção de gases in vitro é importante no estudo dos parâmetros cinéticos das frações que compõem os alimentos, pois reflete a taxa e extensão em que os componentes são fermentados pelos microrganismos do rúmen (Cabral et al., 2002).O estudo do valor nutritivo da forragem possibilita identificar as principais causas limitantes do nível de produção, o que permite deduzir estratégias de manejo para aumento da produção animal. Em decorrência da estacionalidade quantitativa e qualitativa observada ao longo do an...
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