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Effects of dietary crude protein and tannic acid on nitrogen excretion, urinary nitrogenous composition and urine nitrous oxide emissions in beef cattle
Author(s) -
Zhou Ke,
Bao Yu,
Zhao Guangyong
Publication year - 2019
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1111/jpn.13186
Subject(s) - excretion , urine , zoology , chemistry , urea , dry matter , tannic acid , feces , beef cattle , urinary system , endocrinology , biology , biochemistry , paleontology , organic chemistry
Two consecutive trials were carried out to study the effects of dietary crude protein (CP) and tannic acid (TA) on nitrogen (N) metabolism of beef cattle and consequently, the N 2 O emissions from the urine of cattle. In Trial I, eight growing castrated cattle were used as the experimental animals. Two levels of dietary CP (110.6 and 135.7 g/kg dry matter [DM]) and two levels of TA (0 and 16.9 g/kg DM) were allocated in a replicated 2 × 2 crossover design. In Trial II, the N 2 O emissions from the urine of cattle collected from Trial I were determined using the static incubation technique. An interaction between dietary CP and TA on the urinary N excretion ( p < .05) was found but not on the N 2 O‐N emission of cattle urine. Increasing dietary CP level from 110.6 g/kg DM to 135.7 g/kg DM increased the total N excretion ( p < .001), the N retention ( p < .05) and the ratio of urinary urea‐N/urinary N ( p < .01), did not affect the N use efficiency (NUE; p > .05) and shifted the N excretion from faeces to urine. Increasing the dietary CP level increased the N 2 O‐N emission of cattle urine. Dietary addition of TA decreased the urinary excretions of urea ( p < .001) and shifted the N excretion from urine to faeces, did not affect the NUE of beef cattle ( p > .10), and decreased the N 2 O‐N emission of cattle urine. Pyrogallol and resorcinol of the TA metabolites were detected in urine with dietary addition of TA. Feeding beef cattle with relatively low CP level and adding TA in rations are effective approaches to mitigate the N 2 O‐N emissions from cattle urine.