ORIGINAL PAPER
Effect of rumen-protected protein supplemented
with three amino acids on milk yield, composition
and fatty acid profile in dairy cows
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1
Research Institute for Cattle Breeding, Ltd., Department Pohořelice,
Vídeňska 699, Pohořelice 691 23, Czech Republic
2
Department of Milk Hygiene and Technology, Faculty of Veterinary Hygiene and Ecology,
University of Veterinary and Pharmaceutical Sciences,
Brno, Czech Republic
Publication date: 2006-01-06
Corresponding author
J. Třináctý
Research Institute for Cattle Breeding, Ltd., Department Pohořelice,
Vídeňska 699, Pohořelice 691 23, Czech Republic
J. Anim. Feed Sci. 2006;15(1):3-15
KEYWORDS
ABSTRACT
The objective of this study was to determine the influence of rumen-protected protein supplemented
with the amino acids lysine (Lys), methionine (Met) and histidine (His) added either as a powder or
in the form of rumen-protected tablets to the rumen of dairy cows on the yield, composition and
technological suitability of milk. The experiment was carried out on three lactating Holstein cows with
an average weight of 523 kg fitted with ruminal and duodenal cannulas. The experiment was divided
into 4 periods of 14 d (10 d preliminary period and 4 d experimental period). In the first period one
cow received the tablets (T) and the other two received the non-tableted mixture (C) with the same
composition. In the subsequent period the design was opposite. Cows were fed a diet based on maize
silage, lucerne hay and a supplemental mixture. Powder or tablets consisted of purified soya-protein
HP 300, Lys, Met and His. Average milk yield in C cows was 16.73 kg and was significantly lower
than in T cows (17.8 kg; P<0.05). Protein, fat and lactose contents were unaffected by the treatment.
Protein yield was lower (529.5 g/d) in the C than in the T (569.3 g/d; P<0.05) cows. The increase in
milk protein yield in T cows was followed closely by progressive increases in casein content (2.46 vs
2.68%). The content of short- and medium-chain fatty acids was higher and the proportion of C18:1,
C18:2, C18:3n3 and C20:1 was lower in the C than in the T (P<0.05) animals. The proportion of
UFA (both MUFA and PUFA) was increased and that of SFA in milk (P<0.05) was decreased in the T
animals. The total SFA:UFA ratio was higher in C compared with T cows (1.89 vs 1.52; P<0.05).
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