Salinomycin and virginiamycin for lactating cows supplemented on pasture

Animals on pasture generally show higher feed efficiency as a result of the use of antibiotics. This study evaluated the effect of the antimicrobials salinomycin and/or virginiamycin on production and the ruminal parameters of supplemented dairy cows grazing on Panicum maximum cv. Tanzania. Twelve Holstein/Zebu multiparous cows were used, distributed in three Latin squares, one for the evaluation of ruminal parameters, and the others for production parameters. Cows on pasture were fed 50 % of their estimated intake with corn silage and concentrate supplements containing salinomycin, virginiamycin or a combination of additives, in doses of 120 and 150 mg kg−1, respectively. There were no differences in milk production and composition, energy and nitrogen balance, dry matter digestibility and feeding behavior. However, salinomycin and virginiamycin each reduced pasture and total dry matter intake by about 14 % and 10 %, with a consequent improvement in feed efficiency

Salinomycin and virginiamycin for lactating cows supplemented on pasture

Animals on pasture generally show higher feed efficiency as a result of the use of antibiotics. This study evaluated the effect of the antimicrobials salinomycin and/or virginiamycin on production and the ruminal parameters of supplemented dairy cows grazing on Panicum maximum cv. Tanzania. Twelve Holstein/Zebu multiparous cows were used, distributed in three Latin squares, one for the evaluation of ruminal parameters, and the others for production parameters. Cows on pasture were fed 50 % of their estimated intake with corn silage and concentrate supplements containing salinomycin, virginiamycin or a combination of additives, in doses of 120 and 150 mg kg−1, respectively. There were no differences in milk production and composition, energy and nitrogen balance, dry matter digestibility and feeding behavior. However, salinomycin and virginiamycin each reduced pasture and total dry matter intake by about 14 % and 10 %, with a consequent improvement in feed efficiency

In vitro kinetic parameters of marandu palisadegrass associated with nonfiber carbohydrates

Objetivou-se avaliar efeitos de níveis (0, 10, 20 e 30%) de amido ou glicose associado ao capim Urochloa brizantha cv. Marandu sobre os parâmetros cinéticos e digestão da fibra do por meio da técnica in vitro de produção de gases. O experimento foi organizado em um delineamento inteiramente casualizado, com quatro tratamentos e 6 repetições para cada fonte energética. O capim Marandu associado aos níveis de carboidratos não fibrosos foi incubado em frascos de 120 mL, com tampão de McDougall e inóculo ruminal proveniente de dois ovinos canulados no rúmen. Foram realizadas leituras da pressão dos gases no interior dos frascos, bem como dois frascos foram retirados nos tempos 24, 48 e 96 horas (h) para avaliação da FDN residual. Utilizou-se modelo logístico com um compartimento para estimar os parâmetros cinéticos para a forragem ou da forragem associada a amido, entretanto foi necessário utilizar o modelo bicompartimental quando da adição de glicose. Cada 1% de amido adicionado promoveu aumento linear na produção total de gases em 0,2254 mL e redução do período de latência em 0,2451 h, mas não afetou a taxa de digestão. Já os níveis de glicose causaram efeito quadrático sobre a taxa de digestão e latência, sendo estimado valor mínimo da taxa de digestão de 0,01689 h-1 no nível de glicose de 10,07% e latência mínima igual a zero. Os níveis de amido causaram redução linear da digestão da FDN em 0,296% apenas no tempo 24 h, enquanto que os níveis de glicose reduziram linearmente a digestão da FDN em todos os tempos avaliados (0,3269; 0,4171 e 0,234%, nos tempos 24, 48 e 96 h, respectivamente). Os níveis de glicose promovem efeitos diferenciados sobre os parâmetros cinéticos da produção de gás in vitro do capim Marandu comparado à suplementação com amido, destacando seus efeitos negativos prolongados sobre a digestão da FDN.This study aimed to evaluate the effects of different levels (0, 10, 20 and 30%) of starch or glucose associated with marandu palisadegrass (Urochloa brizantha cv. Marandu) on its kinetic parameters and fiber digestion by the in vitro gas production technique. The experiment was arranged in a completely randomized design, with four treatments and six replications for each energy source. The marandu palisadegrass associated with nonfiber carbohydrate levels was incubated in 120 ml bottles, with McDougall buffer and rumen fluid from two rumen-cannulated sheep. Readings were taken of gas pressure within the bottle, and two vials were removed at 24, 48 and 96 hours (h) to assess residual neutral detergent fiber (NDF). The one-pool logistic model was used to estimate the kinetic parameters for pure forage and forage associated with starch, however it was necessary to use the two-pools model when glucose was added. Each 1% of added starch promoted a linear increase in total gas production of 0.2254 ml and a decrease in lag time of 0.2451 h, but did not affect the digestion rate. Glucose levels had a quadratic effect on digestion rate and lag time, with a minimum estimated value for digestion rate of 0.01689 h-1 at a glucose level of 10.07% and a minimum lag time of zero. Starch levels caused a linear reduction in NDF digestion of 0.296% only at 24 h, while glucose levels linearly reduced the NDF digestion in all evaluated times (0.3269, 0.4171 and 0.2340% at 24, 48 and 96 h, respectively). Glucose levels promoted different effects on the in vitro gas production kinetic parameters of marandu palisadegrass compared to starch supplementation, highlighting the prolonged negative effects on NDF digestion

Supplementation strategies for dairy cows kept in tropical grass pastures

Objetivou-se avaliar estratégias de suplementação sobre o consumo de forragem e nutrientes, digestibilidade dos nutrientes, comportamento ingestivo, produção e composição do leite, eficiência alimentar, balanço de compostos nitrogenados e variação de peso corporal de vacas leiteiras mantidas em pastos de capim Tanzânia (Panicum maximum Jacq. cv. Tanzânia) no período seco do ano. Foram utilizadas oito vacas mestiças HolandêsXZebu no terço final de lactação, com peso médio de 505±44 kg e produção de leite inicial de 9,0±1,44 kg dia-1, em delineamento quadrado latino 4X4 duplo. O experimento consistiu de quatro períodos experimentais de 17 dias cada, sendo nove dias inicias para adaptação e oito dias para coleta de dados. Os tratamentos consistiram de mistura mineral e suplementos (energético, proteico ou múltiplo) fornecidos na quantidade de 2 kg por vaca dia-1. Os suplementos promoveram aumento no consumo de matéria seca e nutrientes (P 0,05). Foi observado aumento (P 0,05) na eficiência alimentar. O desempenho de vacas leiteiras mantidas em pastagem de gramínea tropical pode ser melhorado com o uso de suplementação concentrada de 0,40% do peso corporal dia-1, sem comprometer o consumo de forragem dos animais.This study aimed to evaluate the supplementation strategies on forage intake and nutrient digestibility, feeding behavior, milk production and composition, feed efficiency, nitrogen balance and body weight change of dairy cows kept in Tanzania grass pastures (Panicum maximum Jacq. cv. Tanzania) in the dry season. We used eight crossbred Holstein and Zebu cows in the final third of lactation, with an average weight of 505±44 kg and initial milk production of 9.0±1.44 kg day-1, in a double 4X4 Latin square design. The experiment consisted of four experimental periods of 17 days each, with nine days for initial adaptation and eight days to collect data. Treatments consisted of mineral mix and supplements (energy, protein or multiple) provided in the amount of 2 kg per cow day-1. Supplements promoted increased consumption of dry matter and nutrients (P 0.05). There was an increase (P < 0.05) of 19.51% in milk production in the supplemented animals and productive responses approximate marginal 0.64 kg of milk for each kg of supplied supplement, however, the different supplements promoted a drop in the milk fat. There were higher net energy values of animal lactation for protein-energy supplementation and mineral mixture, but no change was observed in feed efficiency and energy efficiency. The performance of dairy cows kept in tropical grass pasture can be improved with the use of a concentrate supplementation of 0.40% of body weight per day-1 without compromising the forage intake of animals