Document Detail


Optimized dairy grazing systems in the northeast United States and New Zealand. I. Model description and evaluation.
MedLine Citation:
PMID:  10480106     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Parallels exist in the recent developments of dairy systems in the Northeast United States and New Zealand because of greater use of pasture grazing and feed supplements, respectively. Lessons can be learned from each system. However, major differences exist between the regions in the patterns of pasture production, the costs of supplementary feed, and milk prices. These differences affect the optimum use of feed. In this paper, a linear programming model developed to determine optimum feeding strategies for dairy systems in each country is presented. The model optimizes grazing management (rotation lengths) and the conservation of pasture subject to constraints on their use. Other feed resources include N fertilizer, grain, corn silage, and alfalfa silage. All feeds are represented in energy terms. The substitution of pasture intake by grain and forage supplements is included, and cow performance can be optimized by choosing from 73 seasonal calving herds that vary in calving date, lactation length, and daily milk production. The model predicts that marginal responses to grain feeding are between 1.35 and 1.8 kg of milk/kg of grain dry matter supplement, well within the range of responses reported in the literature. Evaluation of the model against data from nine grazing system treatments in New Zealand and two in Pennsylvania showed that model predictions averaged +3% (New Zealand) and +0.04% (Northeast) of measured milk production. The model could be used with confidence to study systems in both the Northeast United States and New Zealand.
Authors:
D G McCall; D A Clark; L J Stachurski; J W Penno; A M Bryant; B J Ridler
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of dairy science     Volume:  82     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  1999 Aug 
Date Detail:
Created Date:  1999-10-04     Completed Date:  1999-10-04     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1795-807     Citation Subset:  IM    
Affiliation:
AgResearch, Ruakura Research Centre, Hamilton, New Zealand.
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MeSH Terms
Descriptor/Qualifier:
Agriculture
Animal Feed*
Animals
Cattle
Cereals
Dairying / economics,  methods*
Eating
Energy Intake
Female
Fertilizers
Lactation
Mathematics
Milk / economics
Models, Theoretical
New Zealand
Nitrogen
Nutritional Requirements
Silage
Species Specificity
United States
Chemical
Reg. No./Substance:
0/Fertilizers; 7727-37-9/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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