Document Detail

Effect of modified dry period lengths and bovine somatotropin on yield and composition of milk from dairy cows.
MedLine Citation:
PMID:  15483158     Owner:  NLM     Status:  MEDLINE    
Dry periods of 40 to 60 d have been an industry standard because dry periods <40 d have resulted in reduced milk yields in the subsequent lactation by 10 to 30%. However, recent research has demonstrated no production losses for cows given a 30-d dry period. The current study evaluated milk production effects of shortened or omitted dry periods for cows at mature-equivalent production >12,000 kg of milk and treated with bovine somatotropin (bST). The study used 2 commercial dairies and one university dairy and included 4 treatments. Five multiparous and 5 primiparous cows from each farm were assigned to each treatment: 1) 60-d dry period, label use of bST (60DD); 2) 30-d dry period, label use of bST (30DD); 3) continuous milking, label use of bST (CMLST); and 4) continuous milking with continuous use of bST (CMCST). Per label, bST use started at 57 to 70 d in milk and ended 14 d before drying (60DD and 30DD) or expected calving date (CMLST). In primiparous cows, average milk yields during the first 17 wk of lactation were reduced for cows on treatments 30DD, CMLST, and CMCST vs. the 60DD treatment. (38.3, 35.1, and 37.5 vs. 44.1 +/- 1.3 kg/d, respectively). For multiparous cows, respective milk yields did not differ (46.6, 43.4, 46.5, and 47.7 +/- 2.1 kg/d). Shortened or omitted dry periods may impede mammary growth in primiparous cows, resulting in reduced milk yield in the subsequent lactation. In contrast, a shortened or omitted dry period with either bST protocol did not alter production in multiparous cows treated with bST. Quality aspects of prepartum milk and colostrum require additional characterization. For multiparous cows, milk income generated for short dry periods or for continuous milking might increase their profitability. At 17 wk of the subsequent lactation, estimates of the cumulative net margins of multiparous cows on the 30DD treatment and continuous milking treatments exceeded those of cows on the 60DD treatment by 40 dollars to 60 dollars per cow.
E L Annen; R J Collier; M A McGuire; J L Vicini; J M Ballam; M J Lormore
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of dairy science     Volume:  87     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-10-14     Completed Date:  2005-04-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3746-61     Citation Subset:  IM    
Department of Animal Science, University of Arizona, Tucson 85721, USA.
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MeSH Terms
Cattle / physiology*
Dairying / economics,  methods*
Growth Hormone / pharmacology*
Lactation / drug effects*,  physiology
Milk / chemistry*,  secretion*
Postpartum Period
Random Allocation
Reproduction / drug effects
Time Factors
Reg. No./Substance:
89383-13-1/growth hormone, bovine; 9002-72-6/Growth Hormone

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