Performance of supplemented heifers on Marandu grass pastures in the wet-to-dry transition and dry seasons

The objective of the present study was to evaluate the characteristics of the sward canopy of Marandu grass during the rainy season, the wet-to-dry transition and the dry seasons, between March and September 2004, under intermittent grazing, and to correlate those characteristics with the performance of crossbred heifers receiving mineral supplements ad libitum or protein supplements. The experiment consisted of a randomized block design with three blocks (set of 13 paddocks), each containing five crossbred heifers per experimental unit, totaling 15 replicates. The heifers were given protein supplements daily in individual stalls and received an average 4 g/kg/day of the supplement during the rainy season and 5 g/kg/day during the dry season. Their weight gain was assessed monthly. The pasture structure was assessed through destructive sampling, and the bromatological composition of esophageal extrusa samples was also assessed. Analysis of variance was used to assess performance, and regression analysis was used to evaluate the sward canopy characteristics in relation to the months of the year. A cluster procedure was used to determine the similarity between the months of the year under assessment. Two different groups were formed for pasture evaluation: one group including the months of March to July and another group including the months of August and September. The first group exhibited a better canopy structure than the second group. This fact was corroborated by the animal performance, which was lower during the months of the second group. Low-intake protein supplementation was effective in increasing the performance of the grazing heifers. Pasture structure is critical for animal performance in a grazing environment, regardless of the type of supplementation.

Structural characteristics and forage mass of Tifton 85 pastures managed under three post-grazing residual leaf areas

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.

Suplementação como estratégia de produção de carne de qualidade em pastagens tropicais

O manejo do pastejo e a suplementação estratégica permitem maximizar a produção de carne bovina em pastagens de forma sustentável. A intensidade de pastejo influencia diretamente o crescimento individual, taxas de aparecimento e mortalidade de perfilhos, a determinar o acúmulo de forragem e a estrutura do dossel. Dessa forma, nas águas, é função do manejo do pastejo adequar a frequência e intensidade de desfolhação para que o animal possa colher forragem com idade fisiológica e valor nutritivo adequados. A idade e tamanho dos perfilhos determinam a proporção de tecidos de suporte lignificados que reduzem a digestibilidade da forragem. No período seco, o manejo do pasto e a estratégia de diferimento, ao final do período das águas, são determinantes na obtenção de forragem de melhor valor nutritivo. Assim, o manejo das pastagens visa, primeiramente, à produção de forragens com altos teores de fibra potencialmente digestíveis. A partir de então, a caracterização da quantidade e qualidade da forragem são primordiais à adequação dos nutrientes fornecidos, via suplementos, para otimizar a utilização dos recursos forrageiros basais. A suplementação da dieta dos animais em pastejo, com concentrado, permite aumentar o desempenho dos animais, o que reduz a idade de abate e melhora a qualidade da carcaça e da carne obtida, além dos benefícios na preparação dos animais terminados em confinamento. Portanto, o manejo do pastejo e a suplementação da dieta dos animais permitem aumento de produtividade e maior qualidade dos produtos.

Parâmetros parasitológicos e desempenho produtivo de ovinos naturalmente infectados com nematoides gastrintestinais mantidos em diferentes pastagens tropicais

The control of gastrointestinal nematodes of small ruminants is usually done with anthelmintics. However, due to the emergence of ever-increasing parasite resistance to these drugs, looking up an alternative control parasites. One of this is sought in pasture management, as these are the sources of animals` infection by L3 infective larvae of helminths. The aim of this study was to evaluate the performance of sheep to natural infections by gastrointestinal nematodes grazing Panicum maximum cv. Massai and cv. Aruana, and Brachiaria brizantha cv. Piatã and cv. Marandu. The work was conducted from May to August-2011 with 48 male sheeps SRD versus Santa Inês breed. The animals were naturally infected with gastrointestinal nematodes, and maintained in four different cultivars of tropical forage grasses, naturally contaminated with eggs and larvae of gastrointestinal nematodes. Each week the animals were phenotypically characterized by parasitological examinations (eggs per gram of feces - EPG, and feces culture), hematological (packed cell volume PCV, and blood eosinophil count) method to evaluate the Famacha© colorof ocular mucosa, and the measures of body condition score and weight. In pastures was made the recovery of infective larvae in order to determine the quantity of L3 present in the pasture. The experimental design was a randomized completed block with two replications and before the entry of animals in the paddocks, they have been wormed. The experiment was ended when the animals reached 32.0 kg liveweight, and then were slaughtered and autopsies performed for the recovery and identify parasites of the abomasum, small intestine and large intestine. Results were subjected to analysis of variance, t test and Tukey`s test. The animals kept on pastures of Marandu grass had lower EPG counts, higher percentage of packed cell volume and higher average weight; those who remained in the Piatã pasture had lower eosinophil counts per microliter of blood. About the Famacha©, the highest prevalence was Famacha 2, and the body condition score ranged between 2 and 3. The results of feces cultures and recovery of larvae on pastures showed the presence of larvae of Trichostrongylus sp., and at the necropsy too. This way, it was concluded that the grass cultivars influences the sheep parasite load; the Famacha, together with EPG and packed cell volume are important indicators for use in controlling gastrointestinal nematode infections. The Trichostrongylus sp. was the most prevalent parasite in sheep during the rainy season

Estrutura do dossel e acúmulo de forragem dos capins piatã e marandu sob pastejo com ovinos

The objective of this scientific work was to evaluate the tillering and mass production of Brachiaria brizantha Piatã and Marandu grasses with two statures of post-grazing. The experimental lineation was in factorial arrangement (2 pastures x 2 residue stature) with subplots (grazing cycle). The experimental period was from March to October of 2012. The target stature on pre-grazing was 50 cm and on post-grazing 15 and 25 for each cultivar. The following variables were analyzed: tiller population density, forage mass, morphological components, accumulation and accumulation rate. Three grazing cycles were obtained. Marandu grass presented larger forage mass on pre-grazing and lower stem production than piatã grass. No difference was observed between the two cultivars regarding the leaf blade production. There was no difference on forage mass, leaf blade, stem, and dead material production between the two statures of post-grazing. The pastures managed at 25 cm presented accumulation rate compared to those with 15 cm. Concerning the accumulation rate on the two cultivars, piatã and marandu grasses, Marandu grass presented higher amount than the piatã grass, and also presented higher values on the rate of basal tiller appearing on 15 cm stature post-pasture feature. Piatã grass managed at 25 cm developed smaller tiller amount on the second generation and greater tiller amount on the third generation than marandu grass. The greater tiller population density was observed on 25cm post-grazing pastures. There was no statistical difference of density between the two cultivars and between the cycles. Accordingly, it is concluded that piatã and marandu cultivars can be managed with 15cm and 25 cm post-grazing statures

Preference of Atta capiguara (Hymenoptera, Formicidae) for Different Grasses

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Gastrointestinal helminths in calves and cows in an organic milk production system

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Respostas do híbrido de sorgo-sudão às adubações nitrogenada e potássica: características estruturais e produtivas

A pesquisa foi instalada no Setor de Forragicultura da FCAV/UNESP-Jaboticabal, para avaliar o híbrido de sorgo-sudão AG 2501C no outono e inverno. O manejo da pastagem foi conduzido, simulando o sistema de lotação intermitente. O experimento foi desenvolvido de março a setembro de 2002. A forrageira foi submetida a nove tratamentos: três doses de N (100, 200 e 300 kg/ha) e três doses de K (0, 80 e 160 kg/ha de K2O), em delineamento experimental de blocos casualizados com três repetições em esquema de parcelas subdivididas. As características estudadas foram massas, secas, inicial de planta inteira, folha e colmo e massa seca residual; relação lâmina/colmo; índice de área foliar (IAF); interceptação da radiação fotossinteticamente ativa (RFA) e coeficiente de extinção luminosa. Os tratamentos não influenciaram a massa seca inicial (MSI) e residual (MSR) da planta inteira, folha e colmo e massa seca residual. Os resultados médios para MSI, MSR, folha e colmo foram 2801,2; 964,7; 1462,8 e 1085,2 kg/ha de MS, por ciclo de pastejo, respectivamente. Houve redução da relação lâmina/colmo e da porcentagem de folhas, enquanto a porcentagem de colmos aumentou. Houve interação entre N e K para IAF, interceptação de luz e coeficiente de extinção.

Effect of grazing system on fetal development in Nellore cattle

Intensive grazing systems for beef females, based on abundant availability of high quality forages and supplementary concentrates, may affect fetal development. The objective of this study was to determine the effect of grazing system on length of gestation, fetal development, and characteristics of the calf at birth. Twenty-four pregnant (bred to Nellore bulls) Nellore females were allocated into two groups. The control group (G1) grazed Brachiaria decumbens (signal grass) in a traditional (extensive) grazing system and the second group (G2) were managed on Panicum maximumcv. Tanzania 1 (Tanzania grass) in an intensive grazing system. Fetal development was evaluated by ultrasonography on days 31, 45, 59, 94, 122, 220, and 255 of gestation. The diameter of the amniotic and allantoic cavities, crown-rump length, circumference, and diameter of the head and ocular orbit were determined. At birth, calves were weighed and height, length, thoracic circumference, and ocular orbit and bi-parietal diameters were measured. There were no differences (P > 0.05) in fetal development. The G1 cows had a longer gestation period (4.5 days; P < 0.05) and their calves had greater (P < 0.05) weight, height, length, and thoracic circumference at birth. In conclusion, Nellore females raised under intensive pasture management conditions, had significantly shorter gestation and smaller calves at birth than those raised under extensive pasture management conditions. Therefore, adoption of new management practices (e.g. intensive pasture management), should take into consideration animal behavior and productivity. (C) 2003 Elsevier B.V. All rights reserved.

Produção e composição do leite de vacas mantidas em pastagens de capim-elefante submetidas a duas frequências de pastejo

The objective of this study was to evaluate two grazing intervals (IG) for elephant grass (Pennisetum purpureum Schum cv. Cameroon) pasture: one variable, determined by the entry of animals to the paddocks when 95% of active photosynthetic radiation was intercepted by the sward, and fixed 26-day grazing interval. Eight dairy cows were used, averaging 124 days lactation, 516 kg body weight and 17.5 kg daily milk production at the beginning of the trial. The experimental period was 80 days divided into four sub-periods of 20 days each. Data were analyzed in a cross-over design. The grazing frequencies did not influence milk production and composition, plasma urea nitrogen, body condition score and variations in body weight. However, the stocking rate and milk production per hectare were higher for pasture with interval of grazing determined by 95% of active photosynthetic radiation. Thus grazing frequency defined in variable intervals by sward interception of active photosynthetic radiation result in higher milk production per area unit.

Reproductive tract development and puberty in two lines of Nellore heifers selected for postweaning weight

The objective was to evaluate reproductive tract development (ovary and uterus) and onset of puberty in two lines of Nellore heifers (Bos indicus) selected for postweaning weight. A total of 123 heifers, including 46 from the control Nellore line (NeC) and 77 from the selection Nellore line (NeS) were used. Every 18 to 21 days from 12 to 24 months of age, average ovarian area (OVA), endometrial thickness (ETh), and diameter of the largest follicle in each ovary were evaluated (using transrectal ultrasonography), and body weight, hip height, and body condition score were measured. There were no differences between NeS and NeC heifers for ETh or OVA (P < 0.05). Genetic selection for higher postweaning weight had no negative influence on the onset of puberty, with 52% and 48% of NeC and NeS heifers, respectively, pubertal at 24 months of age (P = 0.49). Heifers that reached puberty at the end of the study were heavier (NeC, 296.9 vs. 276.7 kg; NeS, 343.5 vs. 327.9 kg; P < 0.01) and younger (NeC, 23.4 vs. 24.2 mo; NeS, 22.7 vs. 24.0 months; P < 0.01) than those that did not. Furthermore, heifers that were heavier at weaning reached puberty earlier. Pubertal heifers had a greater OVA (4.15 vs. 3.14 cm2; P < 0.01) and ETh (12.15 vs. 9.93 mm; P < 0.01) than nonpubertal heifers. Taken together, OVA and ETh had positive effects (P < 0.01) on the onset of puberty and were suitable indicator traits of heifer sexual precocity in pasture management systems. However, selection for weight did not alter ovarian or endometrial development, or manifestation of puberty at 24 months of age. Among the growth traits studied, weaning weight and weight at puberty had significant positive effects on manifestation of first estrus. © 2013 Elsevier Inc.

Desenvolvimento corporal de novilhas leiteiras suplementadas com minerais inorgânicos e orgânicos em pastejo na época das águas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dinâmica de carbono e nitrogênio em pastos de capim-xaraés submetidos a diferentes resíduos pós-pastejo

Pós-graduação em Zootecnia - FCAV

Produção e perdas de forragem em pastagens dos cultivares Tanzânia e Mombaça de Panicum maximum Jacq. adubadas com doses crescentes de NPK

Pós-graduação em Zootecnia - FCAV

Compostos de reserva das plantas e atividade enzimática do solo em pastos de Brachiaria manejados sob ofertas de forragem e lotação rotacionada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)