Two studies were conducted during the grazing season of 1997. Study 1 consisted of three Experiments, and the objectives were to compare milk production and composition, body weight change and body condition score, and to determine time patterns of grazing between cows supplemented with different forms and amounts of corn. Also rumen fermentation parameters were measured in cows supplemented with two different types of corn. In study 2, milk yield was measured when grazing pasture was supplemented to lactating Holstein cows fed a typical TMR diet. Predominantly orchardgrass pastures with lesser amounts of white clover and Kentucky bluegrass were grazed during both studies. In Experiment 1, 36 Holstein cows were supplemented either with 6, 6, 6, or 4 kg/d DM of high moisture corn, coarsely ground corn, finely ground corn, or high moisture corn in two equal feedings, respectively. Milk yield was similar (30.3 kg/d) among treatments. Milk protein (2.97%) and MUN (14.7 mg/dl) did not differ among treatments. Body weight change and body condition score change were similar among treatments (23.1 kg and -0.24). During Experiment 2, four rumen-cannulated cows in mid-lactation were supplemented 6 kg/d DM of either coarsely ground corn or high moisture corn in two equal feedings. After the p.m. milking, ruminal pH was measured and rumen fluid samples were collected to determine ammonia N and VFA. While grazing, this was repeated at 0.5, 1, 2, 3,...8 h post-corn feeding (0 h). Ruminal pH was similar for both corn supplements and was lowest (5.9 and 5.8) at 5 and 8 h, respectively. Rumen ammonia N concentrations started to increase approximately 2 h after cows began grazing, reaching maximum levels 5 h later. In Experiment 3, the number of cows grazing, lying, or standing were recorded every half hour, for two consecutive days, while grazing. Cows grazed an average of 6.4 h/d, 4.1 h in the afternoon and 2.3 h in the morning. Similarity in milk production, milk composition, BW change, and BCS between treatments indicates that the quality and availability of pasture permitted equal response regardless of the type or amount of corn supplemented. Fifty four Holstein cows in mid lactation were used in Study 2. Cows were fed either a TMR diet only, or were fed TMR during half of the day (after the a.m. or p.m. milking according to the treatment) and supplemented with grazing pasture during the other half of the day. Milk production was slightly but significantly higher for cows on the TMR treatment (29.1 vs. 28.2 and 27.6). No significant difference between treatments was observed in FCM (27.7 kg/d), and milk fat (3.47) and protein percentage (3.23). While BW change did not differ among treatments (25.7 kg), body condition score increased more in cows fed only a TMR diet (0.14 vs. -0.06 and 0.01). The TMR intake was significantly different between treatments, being highest for cows on the TMR treatment and lowest for cows grazing after the p.m. milking (26.6 vs. 20.3 vs. 17.5 kg/d DM). Income over feed cost differed between treatments, and was approximately 15.3% higher for cows supplemented with high quality pasture during the afternoon compared to cows on TMR. Dairy farmers may obtain economical benefits by practicing this type of management during the grazing season with little effect on milk yield. / Master of Science

O comportamento de escolha de locais da pastagem por bovinos pode causar pastejo desuniforme, o que é prejudicial para a produtividade e sustentabilidade do sistema. Em duas invernadas com diversidade topográfica e vegetacional, em Londrina (PR), o uso de subunidades de 1 ha pelos animais foi quantificado pela redução da altura da forragem (capim colonião - Panicum maximum) e observações visuais em pastejo nas subunidades. Os animais utilizados foram novilhas cruzadas Nelore-Charolês, com pelo menos ¾ Nelore. Foram feitas análises de regressão múltipla na tentativa de explicar o uso das subunidades considerando a distância horizontal e vertical da água, declividade, porcentagem de plantas daninhas, número de sombras, proporção de componentes morfológicos e altura da forragem. O efeito da presença de plantas daninhas na proporção de componentes morfológicos da forragem também foi avaliado. O período de ocupação da pastagem foi de 60 dias, de janeiro a março de 2005, e as avaliações foram separadas em quatro quinzenas. O efeito da localização do cocho de sal no uso das subunidades foi avaliado em análise isolada. Em cada uma das quinzenas, a localização do cocho de sal foi alterada de próximo para longe da aguada e o consumo de sal foi quantificado. As alterações na altura da forragem indicaram preferência dos animais por áreas que minimizassem o deslocamento horizontal e vertical em relação à aguada e por áreas com forragem com maior relação folha:haste. A presença de planta daninha em um determinado ponto na pastagem diminuiu a relação folha:haste da forragem e, quando a daninha possuía espinho, a relação folha:haste foi ainda menor, o que sugere subutilização próximo a daninhas ou acúmulo de haste pela forragem em condição de sombreamento. As sombras não foram determinantes importantes na escolha de locais para pastejo e o uso de sombras pelos animais foi praticamente nulo. O cocho de sal não foi eficiente para atrair o gado para áreas subutilizadas. Não foi observado efeito do posicionamento do cocho em relação à aguada no consumo de sal. Os dados de altura da forragem sugerem que, com o avanço do período de ocupação, a escassez de forragem nas áreas preferidas fez com que os animais passassem a freqüentar mais as áreas preteridas. Portanto, foi mostrada uma distribuição temporal do uso da pastagem e por isso a estrutura das plantas das áreas preteridas pode ficar prejudicada se o tempo para que o animal visite estas áreas for grande o suficiente. A implicação prática destas observações é que, para se obter pastejo uniforme, devese evitar a existência de áreas "preferidas" e "preteridas" dentro de uma pastagem, reduzindo as distâncias da aguada e evitando cercar áreas com divergência de topografia e vegetação. As observações visuais de locais de pastejo não foram boa opção de coleta de dados. Um método de estimativa visual de altura e porcentagem de plantas daninhas em parcelas de 1 ha foi testado, e mostrou-se viável. / Cattle selective foraging behavior may cause overuse of some areas and low utilization of others, which is negative to the yield and sustainability of the grazing system. Cattle use of subunits in two pastures with heterogeneous topography and vegetation, in Londrina (PR), was evaluated through sward height monitoring (guinea grass - [i]Panicum maximum[/i]) and visual observations of cattle grazing locations. Animals were Nelore/Charolaise cross-bred heifers with at least ¾ Nelore. Multiple regressions were used to predict the use of subunits using stepwise selection method to select against the independent variables: horizontal and vertical distance from water, slope, weed percentage, tree shade number, forage plant part proportion and sward height. Weed effects on forage plant part proportion were evaluated. The grazing period had 60 days, from January through March 2005, and separated analysis were made for each 15 days period. Effects of salt trough on cattle use of subunits were evaluated. In each of the 15 days period, salt trough was moved from near water to a subunit far from water, and salt intake was measured. Pasture height patterns indicated cattle preference to areas that minimizes horizontal and vertical movements from water, and also areas which forage had higher leaf:stem proportion. Weed presence on a vegetation sample point decreased forage leaf:stem proportion, and when the weed had thorns, the leaf:stem proportion were even higher, suggesting underutilization near weeds or effect of weed shade on forage stem accumulation. Tree shades were not an important factor influencing cattle use of pasture sites, and use of shades by heifers was almost null. Salt trough was not efficient to lure cattle to underutilized areas, and there was no evident effect of salt location on it’s consumption. Pasture sward height reduction was higher in sites close to water at the beginning of grazing period but, at the end of the grazing period, the horizontal distance from water did not predict sward height reduction at one pasture, and on the other pasture, sward height reduction was higher in areas far from water. Sward height data suggests that, along the grazing period, forage became scarce on preferred sites and forced animals to use previously rejected sites. Hence, a temporal distribution of pasture utilization was showed, and forage on rejected areas may get steamy if the time an animal takes to visit these areas is large enough. Practical implications are that, to overcome uneven grazing problems, managers have to avoid presence of "preferred" or "rejected" areas inside a pasture, by reducing distances from water, and enclosing areas of uniform topography and vegetation. Visual observations were not satisfactory as dependent variable to predict cattle use of 1 hectare subunits, due to high variation on cattle location between observations dates. A satisfactory visual estimation method was tested to estimate weed height and percentage on 1 hectare plots.

O comportamento de escolha de locais da pastagem por bovinos pode causar pastejo desuniforme, o que é prejudicial para a produtividade e sustentabilidade do sistema. Em duas invernadas com diversidade topográfica e vegetacional, em Londrina (PR), o uso de subunidades de 1 ha pelos animais foi quantificado pela redução da altura da forragem (capim colonião - Panicum maximum) e observações visuais em pastejo nas subunidades. Os animais utilizados foram novilhas cruzadas Nelore-Charolês, com pelo menos ¾ Nelore. Foram feitas análises de regressão múltipla na tentativa de explicar o uso das subunidades considerando a distância horizontal e vertical da água, declividade, porcentagem de plantas daninhas, número de sombras, proporção de componentes morfológicos e altura da forragem. O efeito da presença de plantas daninhas na proporção de componentes morfológicos da forragem também foi avaliado. O período de ocupação da pastagem foi de 60 dias, de janeiro a março de 2005, e as avaliações foram separadas em quatro quinzenas. O efeito da localização do cocho de sal no uso das subunidades foi avaliado em análise isolada. Em cada uma das quinzenas, a localização do cocho de sal foi alterada de próximo para longe da aguada e o consumo de sal foi quantificado. As alterações na altura da forragem indicaram preferência dos animais por áreas que minimizassem o deslocamento horizontal e vertical em relação à aguada e por áreas com forragem com maior relação folha:haste. A presença de planta daninha em um determinado ponto na pastagem diminuiu a relação folha:haste da forragem e, quando a daninha possuía espinho, a relação folha:haste foi ainda menor, o que sugere subutilização próximo a daninhas ou acúmulo de haste pela forragem em condição de sombreamento. As sombras não foram determinantes importantes na escolha de locais para pastejo e o uso de sombras pelos animais foi praticamente nulo. O cocho de sal não foi eficiente para atrair o gado para áreas subutilizadas. Não foi observado efeito do posicionamento do cocho em relação à aguada no consumo de sal. Os dados de altura da forragem sugerem que, com o avanço do período de ocupação, a escassez de forragem nas áreas preferidas fez com que os animais passassem a freqüentar mais as áreas preteridas. Portanto, foi mostrada uma distribuição temporal do uso da pastagem e por isso a estrutura das plantas das áreas preteridas pode ficar prejudicada se o tempo para que o animal visite estas áreas for grande o suficiente. A implicação prática destas observações é que, para se obter pastejo uniforme, devese evitar a existência de áreas “preferidas” e “preteridas” dentro de uma pastagem, reduzindo as distâncias da aguada e evitando cercar áreas com divergência de topografia e vegetação. As observações visuais de locais de pastejo não foram boa opção de coleta de dados. Um método de estimativa visual de altura e porcentagem de plantas daninhas em parcelas de 1 ha foi testado, e mostrou-se viável. / Cattle selective foraging behavior may cause overuse of some areas and low utilization of others, which is negative to the yield and sustainability of the grazing system. Cattle use of subunits in two pastures with heterogeneous topography and vegetation, in Londrina (PR), was evaluated through sward height monitoring (guinea grass - [i]Panicum maximum[/i]) and visual observations of cattle grazing locations. Animals were Nelore/Charolaise cross-bred heifers with at least ¾ Nelore. Multiple regressions were used to predict the use of subunits using stepwise selection method to select against the independent variables: horizontal and vertical distance from water, slope, weed percentage, tree shade number, forage plant part proportion and sward height. Weed effects on forage plant part proportion were evaluated. The grazing period had 60 days, from January through March 2005, and separated analysis were made for each 15 days period. Effects of salt trough on cattle use of subunits were evaluated. In each of the 15 days period, salt trough was moved from near water to a subunit far from water, and salt intake was measured. Pasture height patterns indicated cattle preference to areas that minimizes horizontal and vertical movements from water, and also areas which forage had higher leaf:stem proportion. Weed presence on a vegetation sample point decreased forage leaf:stem proportion, and when the weed had thorns, the leaf:stem proportion were even higher, suggesting underutilization near weeds or effect of weed shade on forage stem accumulation. Tree shades were not an important factor influencing cattle use of pasture sites, and use of shades by heifers was almost null. Salt trough was not efficient to lure cattle to underutilized areas, and there was no evident effect of salt location on it’s consumption. Pasture sward height reduction was higher in sites close to water at the beginning of grazing period but, at the end of the grazing period, the horizontal distance from water did not predict sward height reduction at one pasture, and on the other pasture, sward height reduction was higher in areas far from water. Sward height data suggests that, along the grazing period, forage became scarce on preferred sites and forced animals to use previously rejected sites. Hence, a temporal distribution of pasture utilization was showed, and forage on rejected areas may get steamy if the time an animal takes to visit these areas is large enough. Practical implications are that, to overcome uneven grazing problems, managers have to avoid presence of “preferred” or “rejected” areas inside a pasture, by reducing distances from water, and enclosing areas of uniform topography and vegetation. Visual observations were not satisfactory as dependent variable to predict cattle use of 1 hectare subunits, due to high variation on cattle location between observations dates. A satisfactory visual estimation method was tested to estimate weed height and percentage on 1 hectare plots.

Made available in DSpace on 2014-06-11T19:33:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-11Bitstream added on 2014-06-13T19:04:38Z : No. of bitstreams: 1 casagrande_dr_dr_jabo.pdf: 1193230 bytes, checksum: f4942366b12e0580d2389de8bbd1e175 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se com presente trabalho avaliar as características estruturais do dossel, o comportamento e o desempenho de novilhas de corte, suplementadas, em pastagem de capim-marandu submetidas à diferentes intensidade de pastejo, sob lotação contínua, assim como o efeito do histórico desses fatores sobre a fase de terminação. Para isso realizou-se quatro experimentos. No primeiro foram avaliadas três ofertas de forragem aliadas a dois tipos de suplementação, sal mineral e suplemento protéico energético. No segundo e terceiro experimentos os tratamentos foram três alturas do dossel aliados a três suplementos, sal mineral e dois suplementos protéicos energéticos. E no quarto foi estudado o efeito destes tratamentos sobre a terminação no confinamento ou no pasto. Observou que a altura do dossel influenciou todas as características estruturais do pasto. A suplementação não interferiu na estrutura do dossel, porém tendeu a reduzir o tempo de pastejo dos animais, principalmente nos períodos que antecederam o fornecimento do suplemento, contudo sem afetar o consumo de forragem. O uso de suplemento protéico energético aumentou o desempenho animal. Os fatores relacionado a fase de recria interferiram no período de terminação, porém não afetaram as características das carcaças. A terminação em confinamento aumentou a deposição de gordura nas carcaças e cortes cárneos. Concluiu-se que pastos de capim-marandu sob lotação contínua, sob pastejo por novilhas em recria, destinadas ao abate, podem ser manejados com alturas entre 15 a 35 cm, sendo a altura 25 cm a mais indicada. Suplementação protéica energética aumenta o desempenho animal e a produtividade do sistema / The objective of this study was to evaluate the structural characteristics of the canopy, grazing behavior, and performance of beef heifers supplemented at pasture of Marandu grass submitted to different grazing intensity under continuous stocking rate, and the effect of these historical factors on the finish of these, in different systems. Four experiments were conducted. The first evaluated three forage allowances combined with two types of supplementation, mineral and protein/energy supplement. In the second and third experiments the treatments were three canopy heights combined with three supplements: mineral and two protein/energy supplements. And in the fourth, studied the effect of these treatments on the finish system, feedlot or in pasture. It was observed that the height of the canopy affected all the structural characteristics of the pasture. Supplementation did not affect the structure of the pasture canopy, but tended to reduce the grazing time of the animals, especially in periods leading up to the supplement supply, however forage intake was not altered. Concentrate supplementation increased animal performance. At all the evaluated situations the animals’ weight gain was limited by energy intake. Factors related to the growing phase interfered in the finishing period, but did not affect the heifers’ carcass characteristics. The finishing in feedlot increased fat deposition in the carcasses and in the meat cuts. It was concluded that Marandu grass pasture under continuous stocking, grazing by growing beef heifers intended for slaughter, can be managed in heights between 15 and 35 cm height, and 25 cm appears to be most appropriate. Protein/energy supplementation increases animal performance and system productivity

Resumo: Objetivou-se com presente trabalho avaliar as características estruturais do dossel, o comportamento e o desempenho de novilhas de corte, suplementadas, em pastagem de capim-marandu submetidas à diferentes intensidade de pastejo, sob lotação contínua, assim como o efeito do histórico desses fatores sobre a fase de terminação. Para isso realizou-se quatro experimentos. No primeiro foram avaliadas três ofertas de forragem aliadas a dois tipos de suplementação, sal mineral e suplemento protéico energético. No segundo e terceiro experimentos os tratamentos foram três alturas do dossel aliados a três suplementos, sal mineral e dois suplementos protéicos energéticos. E no quarto foi estudado o efeito destes tratamentos sobre a terminação no confinamento ou no pasto. Observou que a altura do dossel influenciou todas as características estruturais do pasto. A suplementação não interferiu na estrutura do dossel, porém tendeu a reduzir o tempo de pastejo dos animais, principalmente nos períodos que antecederam o fornecimento do suplemento, contudo sem afetar o consumo de forragem. O uso de suplemento protéico energético aumentou o desempenho animal. Os fatores relacionado a fase de recria interferiram no período de terminação, porém não afetaram as características das carcaças. A terminação em confinamento aumentou a deposição de gordura nas carcaças e cortes cárneos. Concluiu-se que pastos de capim-marandu sob lotação contínua, sob pastejo por novilhas em recria, destinadas ao abate, podem ser manejados com alturas entre 15 a 35 cm, sendo a altura 25 cm a mais indicada. Suplementação protéica energética aumenta o desempenho animal e a produtividade do sistema / Abstract: The objective of this study was to evaluate the structural characteristics of the canopy, grazing behavior, and performance of beef heifers supplemented at pasture of Marandu grass submitted to different grazing intensity under continuous stocking rate, and the effect of these historical factors on the finish of these, in different systems. Four experiments were conducted. The first evaluated three forage allowances combined with two types of supplementation, mineral and protein/energy supplement. In the second and third experiments the treatments were three canopy heights combined with three supplements: mineral and two protein/energy supplements. And in the fourth, studied the effect of these treatments on the finish system, feedlot or in pasture. It was observed that the height of the canopy affected all the structural characteristics of the pasture. Supplementation did not affect the structure of the pasture canopy, but tended to reduce the grazing time of the animals, especially in periods leading up to the supplement supply, however forage intake was not altered. Concentrate supplementation increased animal performance. At all the evaluated situations the animals' weight gain was limited by energy intake. Factors related to the growing phase interfered in the finishing period, but did not affect the heifers' carcass characteristics. The finishing in feedlot increased fat deposition in the carcasses and in the meat cuts. It was concluded that Marandu grass pasture under continuous stocking, grazing by growing beef heifers intended for slaughter, can be managed in heights between 15 and 35 cm height, and 25 cm appears to be most appropriate. Protein/energy supplementation increases animal performance and system productivity / Orientador: Ricardo Andrade Reis / Coorientador: Telma Teresinha Berchielli / Banca: Sila Carneiro da Silva / Banca: Marco Antonio Alvares Balsalobre / Banca: Flavio Dutra de Resende / Banca: Alexandre Amstalden Moraes Sampaio / Doutor