Incorporation of endogenous urea nitrogen into amino acids of milk in goats fed diets with various protein levels
Journal Title: Journal of Animal and Feed Sciences - Year 2014, Vol 23, Issue 3
Abstract
The aim of the study was to estimate how much endogenous urea nitrogen (EUN) was incorporated into various amino acids of milk protein when goats were fed low (LP), medium (MP), or high protein (HP) diets in a 3 × 3 Latin-square design. Three Alpine goats of about 35 kg body weight fitted with a catheter into the jugular vein were fed isoenergetic diets containing 11% (LP), 13% (MP), or 16% (HP) crude protein in dry matter. They were continuously infused with 15N urea into the jugular vein for 6 days. Daily milk yield was 1.58, 1.49 and 1.77 g. Milk urea concentrations were 139, 342 and 451 mg · l–1, whereas plasma urea was 178, 356 and 667 mg · l –1 in groups LP, MP and HP, respectively. Samples of milk protein were hydrolysed with 6 M HCl, and then free amino acids were converted into butyl derivatives using HCl in butanol, followed by N-acylation using trifluoroacetic acid anhydride. The amino acid derivatives were analysed using a gas chromatograph equipped with a mass detector. 15N-excess after a six-day infusion of labelled urea was significantly higher (P < 0.05) in the vast majority of amino acids of milk protein from goats fed the LP diet in comparison with goats fed the HP diet. Therefore, the protein level of diets affects the incorporation of EUN into amino acids of milk protein. EUN was incorporated primarily into glutamic acid, methionine and arginine. At all levels of nitrogen in the diets, the incorporation of 15N into phenylalanine was very low.
Authors and Affiliations
J. P. Michalski, M. Czauderna, W. Litwin, N. Puzio, J. Kowalczyk
Keywords
Related Articles
- EP ID EP75693
- DOI -
- Views 90
- Downloads 0
Nutritional and energy value of wheat cultivars for broiler chickens
Wheat (Triticum aestivum L.) grain of 6 spring and 3 winter cultivars was analysed for nutrients content including amino acids, fatty acids, starch, sugars and fibre, and dietary fibrę fractions. Digestibility of main nu...
Modelling of individual lactation curves of Tunisian Holstein-Friesian cows for milk yield, fat, and protein contents using parametric, orthogonal and spline models
Different equations were employed to directly model individual lactation curves of Tunisian Holstein-Friesian cows using 260 241 test day records for milk yield, fat, and protein contents. Eleven mathematical models were...
The effect of using soyabean or linseed oil with RRR-d-α-tocopherol or dl-α-tocopherol acetate on haematological parameters and rearing performance of young turkey hens
The aim of the study was to analyse whether and to what degree the use of RRR-d-α-tocopherol in diets containing an oil rich in linoleic or linolenic acid (soyabean or linseed oil, respectively) would make it possible to...
A note on the effect of pre-slaughter transport duration on nutrient composition and fatty acid profile of broiler breast meat
The aim of this study was to investigate the influence of pre-slaughter transport duration, as a stress factor, on nutrient and fatty acid composition of broiler breast meat. The study was conducted on 48 breast muscles...
The use of genetically modified Roundup Ready soyabean meal and genetically modified MON 810 maize in broiler chicken diets. Part 2. Functional status of the small intestine
The effects of genetically modified (GM) soyabean meal (SBM) and GM maize on the functional status of the small intestine of broiler chickens was studied. Eight diets were prepared, based on conventional or GM SBM (GTS 4...