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Avaliação do pH ruminal de vacas leiteiras em Portugal : relação com parâmetros ambientais, produtivos e fisiológicos
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Este trabalho visou avaliar a prevalência de acidose ruminal subaguda (ARSA) em explorações
de vacas leiteiras em Portugal através da análise dos valores de pH do líquido ruminal e
posterior relação com os resultados do Penn State Particle Separator (PSPS), qualidade do
leite, beta-hidroxibutirato (βHB) no leite, dados produtivos individuais, práticas de maneio
alimentar e temperatura ambiente fora e dentro do estábulo. Para colheita do fluido ruminal foi
utilizada uma sonda ruminal, e o pH ruminal foi medido através de um aparelho portátil (lacqua
pmeter) previamente validado. De modo avaliar a granulometria da partícula da dieta recorreuse
ao PSPS. Realizou-se ainda no mesmo momento, a colheita de leite para análise
semiquantitativa dos valores de ẞHB através de tiras Ketotest® (Elanco). Os dados da
qualidade de leite foram obtidos através do contraste leiteiro realizado nas explorações. Para a
análise seleccionaram-se aleatoriamente em média 13 vacas de 14 explorações com 100 a
1000 animais em produção. Em quatro destas explorações tinham sido colocados bolos intraruminais
de monensina (Kexxtone®, Elanco) nos animais incluídos no ensaio. No total foram
amostrados 185 animais, com 5 a 100 dias em leite. Os animais do estudo estavam a ser
alimentados com dieta completa com rácios variados de forragem/concentrado. Em todas as
explorações foi medida a temperatura ambiente e das forragens. O pH ruminal médio foi de
6,24, com 28% das explorações a apresentarem animais positivos a ARSA com uma
prevalência média de 19%. Encontrou-se uma relação positiva entre a PSPS19 e os valores de
pH ruminal (p <0,02). Curiosamente, verificou-se uma tendência positiva entre a quantidade de
alimento retido no crivo de granulometria ≥ 1,18 mm e a produção de leite (p = 0,051). Verificouse
ainda uma relação negativa entre o pH ruminal e a temperatura ambiente dentro dos
pavilhões (p = 0,023) e uma relação positiva entre a prevalência de ARSA e a amplitude de pH
ruminal encontrada em cada exploração (p = 0,003). Identificou-se uma relação negativa entre
o somatório da quantidade de alimento composto complementar e silagem de milho e os valores
médios de pH ruminal. As vacas multíparas apresentaram tendência para teores de gordura no
leite mais elevados do que as primíparas (p = 0,05). A prevalência média de vacas com cetose
subclínica (CSC) por exploração foi de 51%. Não houve diferença estatisticamente significativa
entre a paridade e a probabilidade das vacas apresentarem CSC (p =0,227). Além disso,
constatou-se que, quanto maior é a produção de leite, maior é o risco das vacas terem CSC (p
<0,01). O uso integrado destas metodologias possibilita uma abordagem mais objectiva no
controlo e monitorização da alimentação, do estado hígido e bem-estar da vaca leiteira.
Contudo, mais estudos terão de ser realizados para melhor compreensão da relação entre
algumas variáveis.
ABSTRACT - This study aimed to assess the prevalence of sub-acute ruminal acidosis (SARA) in Portuguese dairy farms by analyzing the pH of the rumen fluid and subsequent relationship with the results of the Penn State Particle Separator (PSPS), milk quality, beta hydroxybutyrate (βHB) in milk, individual production data, feed management practices and environmental temperature outside and inside the barn. To harvest the ruminal fluid it a rumen probe was used, and rumen pH was measured using a portable device (Lacqua pmeter) previously validated. The PSPS was used to evaluate the dietary fiber length. Additionally milk was collected for semi quantitative assessment of ẞHBl through Ketotest® strips (Elanco). The milk quality data was obtained from routine milk recordings performed at the farms. For the study an average of 13 cows were randomly selected from each of 14 farms with 100 to 1000 animals in milk. In four of these farms intra-ruminal monensin device (Kexxtone®, Elanco) had been applied to the animals included in the trial. A total of 185 animals were sampled, with 5 to 100 days in milk. The study animals were eating a total mixed ration (TMR) with varying ratios of forage/concentrate. In all farms the temperature inside and outside of barns was measured. The ruminal pH average was 6.24, with 28% of the farms being positive to ARSA, with an average prevalence of 19%. We found a positive and statistically significant correlation between the amount of fiber sieve with a particle size ≥ 19 mm and pH values (p <0.02). Interestingly, there was a positive relationship between the amount of food held in the particle size of ≥ 1.18 mm sieve and milk production (p = 0.051). There was a negative relationship between rumen pH and environmental temperature inside the pavilions (p = 0.023). A positive correlation between the prevalence of SARA and amplitude ruminal pH found in each scan (p = 0.003) and a negative relationship between the sum of the amount of concentrate and corn silage and the average values of rumen pH, were also found. Multiparous cows tended to have higher milk fat values compared with primiparous cows (p = 0.05). The average prevalence of sub-clinical ketosis (SCK) per farm was 51%. There was no statistically significant difference between the parity and the likelihood for SCK (p =0.227). Furthermore, it was found that higher milk production was a risk factor for cows having SCK (p <0.01). The integrated use of these methods allows for a more objective approach to the control and monitoring of feeding, health status and welfare of the dairy cow. However, more studies need to be conducted to better understand the relationship between some variables.
ABSTRACT - This study aimed to assess the prevalence of sub-acute ruminal acidosis (SARA) in Portuguese dairy farms by analyzing the pH of the rumen fluid and subsequent relationship with the results of the Penn State Particle Separator (PSPS), milk quality, beta hydroxybutyrate (βHB) in milk, individual production data, feed management practices and environmental temperature outside and inside the barn. To harvest the ruminal fluid it a rumen probe was used, and rumen pH was measured using a portable device (Lacqua pmeter) previously validated. The PSPS was used to evaluate the dietary fiber length. Additionally milk was collected for semi quantitative assessment of ẞHBl through Ketotest® strips (Elanco). The milk quality data was obtained from routine milk recordings performed at the farms. For the study an average of 13 cows were randomly selected from each of 14 farms with 100 to 1000 animals in milk. In four of these farms intra-ruminal monensin device (Kexxtone®, Elanco) had been applied to the animals included in the trial. A total of 185 animals were sampled, with 5 to 100 days in milk. The study animals were eating a total mixed ration (TMR) with varying ratios of forage/concentrate. In all farms the temperature inside and outside of barns was measured. The ruminal pH average was 6.24, with 28% of the farms being positive to ARSA, with an average prevalence of 19%. We found a positive and statistically significant correlation between the amount of fiber sieve with a particle size ≥ 19 mm and pH values (p <0.02). Interestingly, there was a positive relationship between the amount of food held in the particle size of ≥ 1.18 mm sieve and milk production (p = 0.051). There was a negative relationship between rumen pH and environmental temperature inside the pavilions (p = 0.023). A positive correlation between the prevalence of SARA and amplitude ruminal pH found in each scan (p = 0.003) and a negative relationship between the sum of the amount of concentrate and corn silage and the average values of rumen pH, were also found. Multiparous cows tended to have higher milk fat values compared with primiparous cows (p = 0.05). The average prevalence of sub-clinical ketosis (SCK) per farm was 51%. There was no statistically significant difference between the parity and the likelihood for SCK (p =0.227). Furthermore, it was found that higher milk production was a risk factor for cows having SCK (p <0.01). The integrated use of these methods allows for a more objective approach to the control and monitoring of feeding, health status and welfare of the dairy cow. However, more studies need to be conducted to better understand the relationship between some variables.
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária
Palavras-chave
Sonda ruminal pH ruminal Acidose ruminal subaguda Penn state particle separator Cetose subclínica Vacas leiteiras Ruminal probe Ruminal pH Sub-acute ruminal acidosis Penn state particle separator Sub-clinical ketosis Dairy cows
Contexto Educativo
Citação
Moreira, B.E.S. (2015). Avaliação do pH ruminal de vacas leiteiras em Portugal : relação com parâmetros ambientais, produtivos e fisiológicos. Dissertação de mestrado. Universidade de Lisboa, Faculdade de Medicina Veterinária, Lisboa.
Editora
Universidade de Lisboa. Faculdade de Medicina Veterinária