Turnover isotópico em leite, sangue e fezes de vacas leiteiras alimentadas com cama de aviário
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Data
2018-08-07
Autores
Seraphim, Luciane do Carmo [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo este estudo foi avaliar o turnover isotópico de δ13C e δ15N no leite, sangue e fezes, ocasionados pela inclusão da cama de aviário na dieta de vacas leiteiras, a fim de determinar o tempo de incorporação do valor isotópico da dieta. Foram utilizadas 12 vacas mestiças, distribuídas em delineamento inteiramente casualizado com seis repetições e dois tratamentos. Os tratamentos foram: T1 – dieta estritamente vegetal durante todo o período experimental; T2 – 50% cama de aviário e 50% vegetal durante o primeiro período experimental e depois dieta vegetal. Foram colhidas amostras diariamente e analisadas com espectrômetro de massas de razão isotópica. Para mensurar o turnover de δ13C e δ15N em determinado intervalo de tempo, foi utilizada a função exponencial de primeira ordem. Os dados isotópicos foram submetidos ao teste t-Student. Os valores isotópicos das fezes e do leite atingiram o patamar de equilíbrio. O sangue não conseguiu atingir o patamar de equilíbrio nos períodos avaliados indicando ser um tecido para detecção de dietas de períodos mais longos. O resultado do teste de t Student (p<0,05) foi semelhante ao encontrado pela análise dos isótopos estáveis mostrando que no primeiro período os valores isotópicos das fezes do T1 diferiram do T2, e para o leite não houve diferença entre os tratamentos. No segundo período, os valores isotópicos das fezes e do leite do T1 não diferiram do T2. Os valores isotópicos de δ 15N no leite para o 1°período diferiram entre o T1 e o T2. De acordo com os resultados obtidos pode-se concluir que o turnover isotópico do 13C nas fezes e do 15N no leite indicam valores de meia vida de 1,4 dias quando houve a troca da dieta contendo cama de aviário para a somente vegetal.
The objective of this study was to evaluate the isotopic turnover of δ13C and δ15N in milk, blood and feces, caused by the inclusion of poultry litter in the diet of dairy cows, in order to determine the incorporation time of the isotopic value of the diet. Were used twelve crossbred cows, distributed in a completely randomized design with six replicates and two treatments. The treatments were T1 - strictly vegetable diet throughout the experimental period; T2 – 50% poultry litter an 50% vegetable during the first experimental period and after vegetable diet. Samples were collected daily and analyzed with isotope ratio mass spectrometers. The first order exponential function was used to measure the turnover of δ13C and δ15N in a certain period of time. Were submitted the isotopic data to Student's t-test. The isotopic values of feces and milk reached the plateau isotope. The blood was not able to reach the plateau isotope in the evaluated periods indicating to be a tissue for detection of diets of longer periods. The results of the Student’s t-test (p <0.05) were similar to those found by the stable isotope analysis, showing that in the first period, the isotopic values of the feces of the T1 differed from the T2, and for the milk there was no difference between the treatments. In the second period, the isotopic values of the feces and the milk of the T1 did not differ from the T2. The isotopic values of δ 15N in milk for the 1st period differed between T1 and T2. According to the results obtained, it can be concluded that the isotopic turnover of 13C in feces and 15N in milk indicate half-life values of 1.4 days when there was a change from diet containing poultry litter to vegetable only.
The objective of this study was to evaluate the isotopic turnover of δ13C and δ15N in milk, blood and feces, caused by the inclusion of poultry litter in the diet of dairy cows, in order to determine the incorporation time of the isotopic value of the diet. Were used twelve crossbred cows, distributed in a completely randomized design with six replicates and two treatments. The treatments were T1 - strictly vegetable diet throughout the experimental period; T2 – 50% poultry litter an 50% vegetable during the first experimental period and after vegetable diet. Samples were collected daily and analyzed with isotope ratio mass spectrometers. The first order exponential function was used to measure the turnover of δ13C and δ15N in a certain period of time. Were submitted the isotopic data to Student's t-test. The isotopic values of feces and milk reached the plateau isotope. The blood was not able to reach the plateau isotope in the evaluated periods indicating to be a tissue for detection of diets of longer periods. The results of the Student’s t-test (p <0.05) were similar to those found by the stable isotope analysis, showing that in the first period, the isotopic values of the feces of the T1 differed from the T2, and for the milk there was no difference between the treatments. In the second period, the isotopic values of the feces and the milk of the T1 did not differ from the T2. The isotopic values of δ 15N in milk for the 1st period differed between T1 and T2. According to the results obtained, it can be concluded that the isotopic turnover of 13C in feces and 15N in milk indicate half-life values of 1.4 days when there was a change from diet containing poultry litter to vegetable only.
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Palavras-chave
cama de aviário, carbono-13, meia-vida, nitrogênio-15, carbon-13, half-life, nitrogen-15, poultry litter