RESUMO

This study compared physiological and productive parameters in 3/4 Holstein × 1/4 Gir dairy cows receiving a prepartum concentrate containing ammonium chloride to reduce urine pH near 7.0 (CON; n = 17), or a commercial anionic supplement to reduce urine pH near 6.0 (SUPP; n = 17). Nonlactating, multiparous, pregnant cows were assigned to receive SUPP or CON beginning 21 d before expected date of calving. Cows were maintained in a single drylot pen with ad libitum access to corn silage, and individually received their prepartum concentrate once daily (0800 h) before calving. Cows from both treatments completely consumed their concentrate allocation within 30 min after feeding. Cow body weight and body condition score were recorded once weekly, urine pH measured every 3 d, and blood samples collected on d -21, -14, -9, -6, and -3 relative to expected calving date. After calving (d 0), cows were moved to an adjacent drylot pen with ad libitum access to water and a total mixed ration, and were milked twice daily (0600 and 1700 h). Cow body weight and body condition score were recorded once weekly and individual milk production was recorded daily until 30 d in milk (DIM). Blood samples were collected before each milking during the first 5 DIM, as well as at 6, 9, 16, 23, and 30 DIM before the morning milking. Based on actual calving dates, cows received SUPP or CON for (mean ± standard error) 19.2 ± 1.2 and 19.0 ± 0.9 d before calving, respectively. Urine pH was less in SUPP versus CON cows during the last 15 d of gestation (6.12 vs. 7.15, respectively). Milk yield during the first 5 DIM and throughout the experimental period was greater in SUPP versus CON cows (by 20 and 14%, respectively), whereas serum Ca concentrations did not differ between treatments during the first 5 DIM. Serum concentrations of fatty acids were greater in SUPP versus CON cows 3 d before and at calving (by 52 and 22%, respectively), whereas SUPP cows had lower serum glucose and cortisol concentration at calving (by 23 and 27%, respectively). Hence, the SUPP treatment decreased prepartum urine pH near 6.0 in Holstein × Gir dairy cows without depressing concentrate intake compared with CON, although total dry matter intake was not evaluated to fully investigate feed intake responses. Moreover, the SUPP treatment transiently affected serum glucose, fatty acids, and cortisol concentrations near the time of calving, and resulted in greater milk yield during the initial 30 DIM compared with CON.

Assuntos

RESUMO

The purpose of the present study was to establish a practical, fast, precise and low-cost procedure to estimate the degree of metabolic acidosis in cattle with acute rumen lactic acidosis for further treatment. The rumen acidosis was induced experimentally in 40 crossbreed rumen-cannulated 1.5-year-old steers. The induction caused the development of the most characteristic clinical signs of acute rumen lactic acidosis, severe rumen acidosis and a moderate metabolic acidosis, which was evidenced by low blood pH, and blood bicarbonate concentration and base excess (BE). A highly positive correlation (r=0.80) between urinary pH and BE concentration, and between urinary pH and blood pH (r=0.75) was observed. The BE concentration estimated by urinary pH was similar to that determined by venous blood gas analysis (P>0.99). Furthermore, the results presented by the predictive formula were very significant. In conclusion, urinary pH is a good tool to predict the quantity of buffers needed to treat metabolic acidosis in cattle with acute rumen lactic acidosis.(AU)

O presente estudo teve como objetivo desenvolver um procedimento de baixo custo, preciso, rápido e prático para estimar o grau de acidose metabólica, para tratar bovinos com quadros de acidose láctica ruminal. A acidose ruminal foi induzida experimentalmente em 40 novilhos mestiços de 1,5 anos de idade, implantados com cânula ruminal. Essa indução causou o surgimento de sinais clínicos muito típicos da enfermidade aguda, com o aparecimento de pronunciada acidose ruminal e acidose metabólica de grau moderado, caracterizado por baixo pH sangüíneo e diminutos teores de bicarbonato e excesso de base (BE) no sangue. Verificou-se uma alta correlação positiva (r = 0,80) entre o pH urinário e o BE e entre o pH urinário e o pH sangüíneo (r = 0,75). A concentração de BE estimado pelo pH urinário foi similar à obtida pela análise do hemogasômetro (P = 0,99). Além disso, os resultados apresentados pela fórmula de predição foram muito significativos. Dessa forma, conclui-se que a mensuração do pH urinário é uma boa alternativa para estimar a quantidade necessária de tampão para tratar o quadro de acidose metabólica em bovinos com acidose láctica ruminal aguda.(AU)

Assuntos

RESUMO

The purpose of the present study was to establish a practical, fast, precise and low-cost procedure to estimate the degree of metabolic acidosis in cattle with acute rumen lactic acidosis for further treatment. The rumen acidosis was induced experimentally in 40 crossbreed rumen-cannulated 1.5-year-old steers. The induction caused the development of the most characteristic clinical signs of acute rumen lactic acidosis, severe rumen acidosis and a moderate metabolic acidosis, which was evidenced by low blood pH, and blood bicarbonate concentration and base excess (BE). A highly positive correlation (r=0.80) between urinary pH and BE concentration, and between urinary pH and blood pH (r=0.75) was observed. The BE concentration estimated by urinary pH was similar to that determined by venous blood gas analysis (P>0.99). Furthermore, the results presented by the predictive formula were very significant. In conclusion, urinary pH is a good tool to predict the quantity of buffers needed to treat metabolic acidosis in cattle with acute rumen lactic acidosis.

O presente estudo teve como objetivo desenvolver um procedimento de baixo custo, preciso, rápido e prático para estimar o grau de acidose metabólica, para tratar bovinos com quadros de acidose láctica ruminal. A acidose ruminal foi induzida experimentalmente em 40 novilhos mestiços de 1,5 anos de idade, implantados com cânula ruminal. Essa indução causou o surgimento de sinais clínicos muito típicos da enfermidade aguda, com o aparecimento de pronunciada acidose ruminal e acidose metabólica de grau moderado, caracterizado por baixo pH sangüíneo e diminutos teores de bicarbonato e excesso de base (BE) no sangue. Verificou-se uma alta correlação positiva (r = 0,80) entre o pH urinário e o BE e entre o pH urinário e o pH sangüíneo (r = 0,75). A concentração de BE estimado pelo pH urinário foi similar à obtida pela análise do hemogasômetro (P = 0,99). Além disso, os resultados apresentados pela fórmula de predição foram muito significativos. Dessa forma, conclui-se que a mensuração do pH urinário é uma boa alternativa para estimar a quantidade necessária de tampão para tratar o quadro de acidose metabólica em bovinos com acidose láctica ruminal aguda.

Assuntos