Crude protein levels in diets of lactating goats: nitrogen balance, urea excretion and microbial protein synthesis

The experiment, conducted at Bahia, Brazil, from May to August 2010, aimed to evaluate the nitrogen (N) balance, urea excretion and microbial protein synthesis in lactating goats fed pelleted concentrates with the addition of crude protein (CP), obtained by replacing alfalfa hay with soybean meal. T...

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Bibliographic Details
Published in:The Journal of agricultural science 2016-08, Vol.154 (6), p.1102-1109
Main Authors: DE JESUS DOS SANTOS, E., ALBUQUERQUE PEREIRA, M. L., PEREIRA DE FIGUEIREDO, M., DE OLIVEIRA SILVA, H. G., FERREIRA DA CRUZ, J., OLIVEIRA BARRETO, F., BORGES SOUSA, L.
Format: Article
Language:English
Subjects:
Alfalfa
alfalfa hay
Animal Research Papers
blood plasma
Body weight
body weight changes
bran
Corn
crude protein
Diet
energy expenditure
Excretion
females
Goats
Hay
lactation
milk
nitrogen
Nitrogen balance
nutrients
Prosopis
Protein synthesis
Saanen
Soil microorganisms
soybean meal
Soybeans
Urea
urine
Zea mays
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Summary:The experiment, conducted at Bahia, Brazil, from May to August 2010, aimed to evaluate the nitrogen (N) balance, urea excretion and microbial protein synthesis in lactating goats fed pelleted concentrates with the addition of crude protein (CP), obtained by replacing alfalfa hay with soybean meal. The diets consisted of different levels of CP and 200 g of roughage (Tifton 85 hay)/kg. Maize and mesquite bran were used as the energy source, with maize replaced by mesquite bran in the ratio of 1·7:1. Eight female Saanen goats were used, confined in individual pens and allocated to a 4 × 4 Latin square design. The N balance in the body was positive, and loss of body weight (–0·03 g/day) was observed for the diet with 190 g CP/kg. The concentration (mg/dl) of urea in urine, milk and blood plasma was positively influenced in a linear form, and the highest rate of increase was found in urine, with 2 mg/dl for every 10 g CP/kg added to the diet. The microbial protein synthesis was not affected, but the diets reduced the microbial protein (44 g/day) and its ruminal production efficiency (30 g/kg total digestible nutrients). The levels above 190 g of CP are not recommended because of the energy expenditure required to excrete the urea.
ISSN:0021-8596
1469-5146
1469-5146
DOI:10.1017/S0021859616000277