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Enfermedades del período de transición posparto y sus efectos en la producción de leche y la fertilidad en un sistema productivo de leche
(Universidad de Chile, 2012)
El período de transición posparto es una etapa decisiva en el futuro productivo de las vacas lecheras. Entre las patologías más frecuentes del período de transición posparto se encuentran: desplazamiento del abomaso a la izquierda, cetosis clínica...
Condición corporal al parto y su relación con el estado de salud de vacas lecheras en el período de transición post parto
(Universidad de Chile, 2010)
Con la evolución de los sistemas de producción de leche, el desafío metabólico enfrentado por las vacas se ha incrementado en los últimos años, especialmente durante el periodo de transición. Después del parto, la vaca puede presentar una serie de...
Incidencia y factores de riesgo asociados al síndrome aborto bovino en vacas lecheras de la zona central
(Universidad de Chile, 2012)
sobrevivencia. La incidencia total de abortos fue de 22,44%, siendo de 14,47% en vaquillas y de 27,44% en vacas (p<0,001), con diferencias significativas entre predios. Vacas de primera, segunda y tercera o más lactancias presentan 1,9 (p<0,001); 2,3 (p<0,001) y...
Consecuencias productivas de partos melliceros en vacas Holstein de las regiones Metropolitana y de Valparaíso
(Universidad de Chile, 2012)
Generalmente se considera que el parto de mellizos en vacas lecheras de alta producción afecta negativamente la fertilidad, la vida productiva y se asocia a una mayor frecuencia de alteraciones al peri y post parto. Los objetivos de esta memoria...
Comparación de conductividad eléctrica de la leche con examen directo de leche y California Mastitis Test
(Universidad de Chile, 2017)
Con el fin de evaluar la eficiencia de la conductividad eléctrica de la secreción láctea en la detección de infecciones intramamarias en vacas lecheras, en el presente estudio se compararon distintos métodos diagnósticos de mastitis. El ensayo se...
In order to evaluate the efficiency of the electrical conductivity of milk in the detection of intramammary infections in dairy cows, in the present study different diagnostic methods for mastitis were compared. The trial was carried out in a confined-system farm where primiparous and multiparous cow populations were studied. Cows were selected according to the variation of the electrical conductivity of the milk (CEL) as positive and negative to then perform direct milk examination (EDL) and California Mastitis Test (CMT) to diagnose clinical mastitis (MC) and subclinical mastitis (MSC), respectively. When comparing the different diagnostic methods, the values obtained for the Chi-square test were low, indicating that there is no significant association between the diagnostic results obtained by the CEL, EDL and CMT tests in the same animals. In order to evaluate the efficiency of CEL as a diagnostic method, sensitivity and specificity were determined considering EDL and CMT as reference tests. In the sampled population, CEL had 72.0% sensitivity and 38.6% specificity in the diagnosis of CM. As a diagnostic method of MSC, a sensitivity of 62.3% and a specificity of 38.2% were observed in the total cow population. Finally, diagnostic yield curves (ROC curves) were obtained for multiparous and primiparous cows that indicated that the CEL measurement has a low diagnostic value as a test. With these results, it is concluded that CEL is a useful method in the diagnosis of mastitis. However, CEL can not be the only diagnostic tool for the detection of mastitis, since there are other variables that could influence the health status of the mammary gland...
In order to evaluate the efficiency of the electrical conductivity of milk in the detection of intramammary infections in dairy cows, in the present study different diagnostic methods for mastitis were compared. The trial was carried out in a confined-system farm where primiparous and multiparous cow populations were studied. Cows were selected according to the variation of the electrical conductivity of the milk (CEL) as positive and negative to then perform direct milk examination (EDL) and California Mastitis Test (CMT) to diagnose clinical mastitis (MC) and subclinical mastitis (MSC), respectively. When comparing the different diagnostic methods, the values obtained for the Chi-square test were low, indicating that there is no significant association between the diagnostic results obtained by the CEL, EDL and CMT tests in the same animals. In order to evaluate the efficiency of CEL as a diagnostic method, sensitivity and specificity were determined considering EDL and CMT as reference tests. In the sampled population, CEL had 72.0% sensitivity and 38.6% specificity in the diagnosis of CM. As a diagnostic method of MSC, a sensitivity of 62.3% and a specificity of 38.2% were observed in the total cow population. Finally, diagnostic yield curves (ROC curves) were obtained for multiparous and primiparous cows that indicated that the CEL measurement has a low diagnostic value as a test. With these results, it is concluded that CEL is a useful method in the diagnosis of mastitis. However, CEL can not be the only diagnostic tool for the detection of mastitis, since there are other variables that could influence the health status of the mammary gland...
Etiología de metritis bovina en rebaños lecheros de las Regiones V y Metropolitana (Chile) y resistencia bacteriana frente a diferentes antimicrobianos
(Universidad de Chile, 2004)
antimicrobianos de uso habitual. Este estudio tuvo por objetivo determinar los patógenos aeróbicos y facultativos aislados más frecuentes en vacas con metritis y su sensibilidad a antimicrobianos. Se aisló un total de 265 cepas bacterianas de 330 muestras...
Conducta de alimentación en vacas lecheras de transición post parto
(Universidad de Chile, 2009)
El presente estudio se realizó para determinar la existencia o ausencia de jerarquía social entre vacas primíparas o multíparas asociada al consumo de la ración, en una lechería comercial de la zona central de nuestro país. La mayor parte de la...
Efecto comparativo de dos preparaciones comerciales de somatotrofina bovina sobre la producción de vacas lecheras
(Universidad de Chile, 2015)
Con el objetivo de comparar los efectos de las dos preparaciones comerciales de somatotrofina bovina recombinante (bSTr) existentes en el mercado, sobre la producción de vacas lecheras, se utilizaron 348 vacas Holstein de una lechería de alta...
In order to compare the effect of two commercial preparations of Recombinant bovine Somatotropin (rbST) on the production of dairy cows, 348 Holstein cows from a high-producing dairy farm, in a confined system located in Casablanca, Valparaíso Region, were used. Cows were randomly assigned from 70-76 days in milk (DIM) to one of two treatment groups. One (n= 161) was treated with the hormonal preparation Boostin® (LG LifeSciences, South Korea) and the other (n=187) with Lactotropina® (Elanco, USA). In both groups, the hormone was administered every 14 days to about 30 days before dry off. Information was obtained from Afimilk® and DairyCOMP® computer programs, collected until the end of the eighth cycle of treatment (approximately 180 DIM). Milk data was processed through a repeated measures analysis of variance. Fertility at first insemination was analyzed by logistic regression to evaluate the risk of pregnancy at first insemination. Days open were analyzed with Kaplan-Meier survival analysis to compare days at pregnancy. Frequencies of clinical mastitis were compared by chi–square test. The risk of mastitis was determined by logistic regression. Monthly somatic cell counts (SCC) were analyzed using repeated measures analysis of variance. Finally, culling rate was assessed by a Kaplan-Meier survival analysis. No significant differences were observed in milk production (p=0.07), averaging 42.3 Lt/day for Boostin®, and 42.8 Lt/day for Lactotropina®. No significant differences on calving-to-conception interval were recorded during the first 180 days of lactation (p=0.19), showing a median of 101 days in Lactotropina® group and 90 days in cows treated with Boostin®. Conception rate at first insemination was 40% in Boostin® treated cows and 32.8% Lactotropina® in treated cows (p=0.16). No significant differences were observed in the risk of pregnancy at first insemination (p>0.05). Cows treated with Lactotropina® have a higher incidence of clinical mastitis (33.5%) compared to Boostin® treated cows (21.1%) (p=0.01) and showed twice as likely to develop mastitis during the treatment period compared to cows treated with Boostin® (p=0.007). Regarding SCC in milk, no significant differences were observed, averaging Lactotropina® and Boostin® groups scores of 2.43±0.08 and 2.4±0.07, respectively (p=0.9). Finally, treatment have no effect on culling rate (p=0.78). In conclusion, there are no substantial differences between hormone preparations regarding milk production, udder health and fertility in high-producing Holstein cows....
In order to compare the effect of two commercial preparations of Recombinant bovine Somatotropin (rbST) on the production of dairy cows, 348 Holstein cows from a high-producing dairy farm, in a confined system located in Casablanca, Valparaíso Region, were used. Cows were randomly assigned from 70-76 days in milk (DIM) to one of two treatment groups. One (n= 161) was treated with the hormonal preparation Boostin® (LG LifeSciences, South Korea) and the other (n=187) with Lactotropina® (Elanco, USA). In both groups, the hormone was administered every 14 days to about 30 days before dry off. Information was obtained from Afimilk® and DairyCOMP® computer programs, collected until the end of the eighth cycle of treatment (approximately 180 DIM). Milk data was processed through a repeated measures analysis of variance. Fertility at first insemination was analyzed by logistic regression to evaluate the risk of pregnancy at first insemination. Days open were analyzed with Kaplan-Meier survival analysis to compare days at pregnancy. Frequencies of clinical mastitis were compared by chi–square test. The risk of mastitis was determined by logistic regression. Monthly somatic cell counts (SCC) were analyzed using repeated measures analysis of variance. Finally, culling rate was assessed by a Kaplan-Meier survival analysis. No significant differences were observed in milk production (p=0.07), averaging 42.3 Lt/day for Boostin®, and 42.8 Lt/day for Lactotropina®. No significant differences on calving-to-conception interval were recorded during the first 180 days of lactation (p=0.19), showing a median of 101 days in Lactotropina® group and 90 days in cows treated with Boostin®. Conception rate at first insemination was 40% in Boostin® treated cows and 32.8% Lactotropina® in treated cows (p=0.16). No significant differences were observed in the risk of pregnancy at first insemination (p>0.05). Cows treated with Lactotropina® have a higher incidence of clinical mastitis (33.5%) compared to Boostin® treated cows (21.1%) (p=0.01) and showed twice as likely to develop mastitis during the treatment period compared to cows treated with Boostin® (p=0.007). Regarding SCC in milk, no significant differences were observed, averaging Lactotropina® and Boostin® groups scores of 2.43±0.08 and 2.4±0.07, respectively (p=0.9). Finally, treatment have no effect on culling rate (p=0.78). In conclusion, there are no substantial differences between hormone preparations regarding milk production, udder health and fertility in high-producing Holstein cows....
Comparación de la eficacia alcanzada en la protección de la salud mamaria, por dos protocolos de vacunación con una bacterina de cepa J5 de Escherichia coli, en vacas lecheras de la Zona Central
(Universidad de Chile, 2012)
La mastitis bovina, en cualquiera de sus formas de presentación, genera importantes pérdidas en los planteles productores de leche. La mastitis clínica ocasionada por bacterias coliformes se hace más importante principalmente en las vacas que se...