The Milk Producer - November 2010 - (Page 34)

RESEARCH By Carol Moore Choosing wisely M Selecting for body condition score can improve your cows’ health and fertility anaging your cows’ body condition score (BCS) has many implications for reproductive performance, milk yield, animal well-being and overall farm profitability. University of Guelph researchers want to improve cow health and fertility using BCS data. Although managing BCS is largely viewed as a nutritional practice, producers should focus on minimizing body condition loss during early lactation. Excessive negative energy balance in early lactation, and the associated decrease in BCS, contributes to ketosis and an increased interval to first ovulation and estrus. Over the years, the dairy industry has focused on selecting for increased milk production. However, this has created more cows using more tissue reserves in early lactation. Genetic differences in a cow’s ability to manage energy reserves have renewed interest for genetic analyses that include BCS. Department of animal and poultry science doctoral candidate Sarah Loker is using BCS data from Valacta, a milk recording agency, and Holstein Canada to examine BCS’s association with other traits, such as milk production and conformation, to determine how it may influence these factors. Loker’s research team wants to use BCS to improve health and fertility genetic evaluations, or select it to improve health and fertility traits indirectly. “If we are selecting for improved BCS, we can minimize the incidences of some metabolic diseases and reduce interval to first ovulation and estrus, which would reduce fertility treatment costs,” says Loker. Health and fertility traits are hard New research that uses body condition score (BCS) to improve your cows’ health and fertility could boost your bottom line by reducing fertility treatment costs. to measure, and have low heritability. Heritability shows how much of the physical differences in measureable traits, such as milk yield and growth rate among cows in the same population, are based on genetics. Such low heritabilities mean genetic improvement for these traits will take more time than if BCS were used instead. BCS is genetically correlated to health and fertility traits, and has a higher heritability. Valacta records BCS multiple times over lactation duration, while Holstein Canada collects BCS once a year at classification. Loker is using this information to model BCS as a curve. She will map the change in BCS genetically across lactations by combining the Valacta and Holstein Canada data. Loker wants to develop a genetic evaluation for BCS, which could generate BCS estimated breeding values. This is a cow’s genetic ability to produce superior offspring based on performance measurements, which could be incorporated into a cow’s Lifetime Profit Index. Carol Moore is a student writer with the University of Guelph’s office of research. Other collaborators in this project include Dr. Filippo Miglior, Agriculture and Agri-Food Canada and Canadian Dairy Network; professors Larry Schaeffer and Vern Osborne, research associate Janusz Jamrozik, department of animal and poultry science, and Catherine Bastin, a visiting scientist from the University of Liège, Belgium. Funding for this project is provided by DairyGen Council of the Canadian Dairy Network and the Natural Sciences and Engineering Research Council. 34 | November 2010 | MilkPRODUCER

Table of Contents for the Digital Edition of The Milk Producer - November 2010

The Milk Producer - November 2010
Contents
Editor's Notes
DFO Chair's Message
Provincial Perspectives
Dairy Update
Farm Finance
DFC Promotion
Issues Update
Research
Applied Science
Ruminations
Markets
New 'N' Noted
Back Forty

The Milk Producer - November 2010