The impact of genomic selection for feed efficiency on the cow-calf sector, performance parameters and underlying biology
The primary purpose of this research is to study the ties between genomic selection for feed efficiency and biological parameters associated with feed efficiency, aiming not only to increase our understanding of the factors determining feed efficiency in beef cattle, but also to identify new phenotypes that could be applied in genetic selection for improved efficiency.
The objectives are to investigate how beef cows differ in performance (size, intake, fertility, calf weaning weight) in relation to their feed efficiency predictions (genomic and based on own and progeny records for feed intake). Biological measures to predict and to monitor biological responses to improvement in feed efficiency will also be developed. These include assessment of metabolic rate through indirect calorimetry, which is the gold standard methodology for studying feed efficiency. In addition, blood samples will be collected hourly during the calorimetry assessment to further study the association of blood metabolites and hormones over continuous 24h. Fecal samples will be collected for further studies on fecal cortisol metabolites as a predictor of feed efficiency. Muscle and liver biopsies will be harvested to study the metabolic rate of these tissues, which are important energy sinks affecting feed efficiency. Rumen fluid will be collected, immune status of dams and calves will be determined and behavioral measures will be taken to determine relationships with efficiency. This project will also utilize the University of Guelph research herd where individual cow feed intake, along with steer intake has been recorded in the database for over 20 years. This complete dataset including pedigree and performance information allows the important relationship between efficiency in the feedlot and performance in beef females to be evaluated in more detail. Relationships between efficiency in the feedlot and cow performance including calf weight, fertility, intake, longevity and cow size will be determined. Cows will have a breeding value estimate for efficiency in the feedlot based on their genomic, progeny and ½ sib records.
The deliverables will include: a) By using the gold standard methodology for studying energy metabolism (indirect calorimeter) and therefore feed efficiency, information about the effectiveness of genotyping for feed efficiency will be generated and evaluated in mature cows and replacement beef heifers. b) By using micro-calorimetry techniques, gene and protein expression and other methods, the energy uptake of key-organs will reveal the individual contribution of these organs to the total energy expenditures of the animal. c) The effects of improved feed efficiency on the immune response of dam and on the amount of antibodies passed to their offspring via colostrum will be determined. d) By studying behavior, alternative traits may be found or further studied related to efficiency. e) By mining existing data, the relationship between feed efficiency in the feedlot sector with cow performance and efficiency measures will be determined.
Estimated Completion: 2016
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