Document Detail

Effect of supplemental conjugated linoleic acids on heat-stressed brown swiss and holstein cows.
MedLine Citation:
PMID:  15829665     Owner:  NLM     Status:  MEDLINE    
Heat-stressed dairy cattle are bioenergetically similar to early-lactation cows in that dietary energy may be inadequate to support maximum milk and milk component synthesis. Study objectives were to evaluate whether conjugated linoleic acids- (CLA-) induced milk fat depression (MFD) during heat stress would allow for increased milk and milk component synthesis. In addition, CLA effects on production variables and its ability to induce MFD were compared between Holstein and Brown Swiss cows. Multiparous cows (n = 8, Holstein; n = 5, Brown Swiss) averaging 97 +/- 17 d in milk were used in a crossover design during the summer (mean temperature-humidity index = 75.7). Treatment periods were 21 d with a 7-d adaptation period before and between periods. During adaptation periods, all cows received a supplement of palm fatty acid distillate (242 g/d). Dietary treatment consisted of 250 g/d of CLA supplement (78.9 g/d of CLA) or 242 g/d of palm fatty acid distillate to provide equal amounts of fatty acids. The CLA supplement contained a variety of CLA isomers (3.0% trans-8, cis-10; 3.4% cis-9, trans-11; 4.5% trans-10, cis-12; and 4.8% cis-11, trans-13 CLA). Treatments were applied 2 x/d with half of the supplement top-dressed at 0600 h and the remainder top-dressed at 1800 h. There was no overall treatment effect on dry matter intake (23.9 kg/d), milk yield (40.0 kg/d), somatic cell count (305,000), protein (2.86%), or lactose content (4.51%) or yields of these milk components. Supplementation with CLA decreased overall milk fat content and yield by 26 and 30%, irrespective of breed. The reduction of milk fat content and yield was greatest on d 21 (28 and 37%, respectively). Energy availability predicted by energy balance was improved with CLA supplementation compared with controls (3.7 vs. 7.1 Mcal/d, respectively). Respiration rate (78 breaths/min) and skin temperature (35.4 degrees C) during maximum heat load were not affected by treatment. The group receiving CLA had higher total milk fat CLA concentration (9.3 vs. 4.9 mg/g). Supplementation with CLA induced MFD and altered milk fat composition similarly between breeds and improved calculated energy balance during heat stress, but had no effect on production measures under these conditions.
C E Moore; J K Kay; R J Collier; M J Vanbaale; L H Baumgard
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of dairy science     Volume:  88     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-04-14     Completed Date:  2005-06-30     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1732-40     Citation Subset:  IM    
Department of Animal Sciences, The University of Arizona, Tucson 85721, USA.
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MeSH Terms
Cattle / physiology*
Cattle Diseases / physiopathology
Dietary Supplements
Energy Metabolism / drug effects
Fatty Acids / analysis
Heat Stress Disorders / veterinary
Hot Temperature*
Lactation / drug effects
Linoleic Acids, Conjugated / administration & dosage*
Lipids / analysis
Milk / chemistry
Milk Proteins / analysis
Species Specificity
Reg. No./Substance:
0/Fatty Acids; 0/Linoleic Acids, Conjugated; 0/Lipids; 0/Milk Proteins

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