Efeito do período de coletas de urina sobre a excreção de creatinina e a produção microbiana em bovinos

• Main Author: Leal, Thalita Lázaro
• Publication Date: 2005
• Format: Master thesis
• Language: por
• Source: LOCUS Repositório Institucional da UFV
• Download full: http://locus.ufv.br/handle/123456789/5026
• topic: Ruminante; Nutrição; Uréia; Bovine; Nutrition; Urea; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The present work was developed based on two experiments. In the first one were used four castred Holstein steers, with initial average live weight of 445 kg, aiming to evaluate variations on the daily urinary excretion of creatinine, urea and purine derivatives, sampling during six consecutive days; and to evaluate the plasma N-urea concentration (NUP) for steers receiving diets with two levels of concentrate and two protein sources. The animals was distribuited in a 4x4 latin square, being the treatments defined by factorial outline 2x2, two urea levels (0 and 100%) replacing soybean meal and two levels of concentrate (0.75% and 1.25% of live weight - LW), the comparison between the evaluation days was lead using a split-plot design. The roughage, constituted of elephant grass silage (80%) and sorghum silage (20%), was supplied at libitum . The urine sampling were done during six consecutive days, using funnels collectors coupled in animals. The nitrogen microbial compounds synthesis was higher (P<0.05) for the higher use of concentrated and lower (P<0.05), when the protein from soybean meal was replaced by urea. There weren t found interaction (P>0.05) between the concentrate and urea levels for the concentration of NUP and urinary excretion of N-urea, neither effect (P>0.05) of urea levels. The urinary excretions of urea, allatoin, uric acid and total purine derivatives were not affected (P>0.05) by the days of urine sampling. In the same way, the amount of estimated microbial protein were not affected (P>0.05) by the days of urine sampling. The creatinine excretion were not affect by the days of urine sampling, presenting average values of 25,47 mg/kgLW, 117,92 mg/kg0.75 or 1,04 mmol/ kg0.75. The second experiment was aimed to determine variations in the daily urinary excretions of creatinine and nitrogen compounds, sampling during six consecutive days for dairy heifers, the effect of number of sampling days in the estimated microbial production was also evaluated. Eleven dairy Holstein heifers, with initial live weight of 280 kg, were used, being a simple sample of a population. To perform the comparison between the sampling days, the variance analyses method was used as a pure error isolation tool, adopting a model which considers the random effect of animal and the constant effect of the evaluation day. The roughage was composed by corn silage supplied at libitum . Daily 2 kg of concentrate ware supplied for each animal. The experimental period had a six day duration because the animals were adapted to the diet. To determine the daily urinary amount, No. 22 or 26 Folley catheters were used. The was not affected (P>0.05) by the days of urine sampling. The urinary excretion of creatinine, urea, allatoin, uric acid and the total purine derivatives excretions were not affected (P>0.05) by the days of urine sampling. The amount of estimated microbial protein were not affected (P>0,05) by the days of urine sampling either. The average value for the creatinine excretion was 30,5 mg/kgLW, 124,84 mg/kg0.75 or 1,1 mmol/kg0.75. Through the results of the two experiments, it can be inferred that the effect absence of the number of days on the creatinine excretion has a important practical application, because it reduces the long durations of sampling, as well as the research expenses, recommending urine samplings of 24-hour duration.