Enhanced bull evaluation: desirable reproductive capacity and improved feed efficiency
Characterizing the biology of beef cattle is a strategy based on fundamentals of nutrition, physiology, reproduction and genetics to deliver practical information and conduct innovative research focused on improving production efficiency of beef cattle farming systems. Today, production efficiency is part of precision agriculture. In fact, one may consider production efficiency the bottom line of a beef cattle production system, especially when efficiency is defined considering animal welfare, environmental awareness and social sustainability. Herein, a brief overview of research findings are summarized as part of an ongoing project led by Beef Farmers of Ontario, and the benefits to Ontario beef production, training of highly qualified personnel and extension activities involving Ontario beef producers are described.
Liver metabolism is a principal topic in this field of research due to its involvement in efficiency of feed utilization and overall health status. Feed efficient bulls were found to have larger hepatocytes (liver cells) and higher oxygen use by the liver. Recently, it was observed that in a group of bulls where several had liver abscesses, a few defined blood parameters (i.e. albumin, cholesterol) were associated with the presence or absence of abscesses. This evidence provides opportunities for detecting abscesses in cattle during the growth and fattening periods, which may enable interventions to minimize decrease in productive performance. This observation may also aid in developing complementary tools for inspectors at slaughterhouses by enhancing their ability to detect liver abscesses with the support of a quick blood test. This study was led by Alaina Macdonald (Veterinary Medicine student).
Digestive function is also a focus of this research, and is the topic of several trials led by Stephanie Lam (M.Sc. student). Key parameters of rumen function such as rumen pH and temperature were evaluated using rumen boluses. The results are indicating no differences in pH or temperature between feed efficient and inefficient cattle. Rumen fluid was also analyzed for microbial species to evaluate relationships with feed efficiency and relative abundance of a diversity of microbes. Additionally, rumen fluid was used to determine the concentration of volatile fatty acids. These primary energetic “coins” for beef cattle seem to be present at higher levels in the rumens of more feed efficient cattle, which suggests these animals may exhibit higher digestive capacity. Another ongoing research topic relating to rumen metabolism is the evaluation of the microstructure of the rumen wall to understand the relationship between rumen structure and metabolism.
Another important aspect of beef production investigated in this project is the relationship between feed efficiency, sexual maturity and semen quality in young bulls. It is known that nutrient metabolism aimed towards superior productive performance could negatively affect sexual maturity and reproductive function, as demonstrated in other farm animals. Expanding on previous results indicating signs of sexual immaturity associated with superior feed efficiency in young bulls, Stéphanie Bourgon (M.Sc. student, sponsored by The Semex Alliance and NSERC) has instigated a comprehensive study to address the biological basis underlying sexual maturity and feed efficiency. Preliminary results indicate the feasibility of assessing sexual development in bulls with the use of testicular ultrasound imaging as a practical approach in commercial operations. Additionally, sequential evaluation of sexual and metabolic hormones throughout the regular testing period has demonstrated potential to predict sexual maturity and semen quality. Ultimately, this research aims to devise complementary methods of assessment to ensure that
This diverse research project also serves to facilitate teaching, training and extension. The substantial research trials result in hundreds of hours working with the cattle and in the lab, and thus constitute an important avenue for students to develop skills in research, cattle handling and husbandry. This experience also involves opportunities to present scientific information to scientists and industry stakeholders, further assisting in the development of individuals capable of communicating information across different audiences. Extension activities are also part of this project, and included an open house in May 2015 hosted by the Elora Beef Research Centre where beef producers, extension personnel and students had the opportunity to exchange information about the key topics of this research.
This project was possible with the scientific support of Dr. Yuri Montanholi (Dalhousie University), Dr. Leluo Guan (University of Alberta), Dr. Mariana Diel de Amorim (University of Prince Eduard Island) and Dr. John Cant (University of Guelph).
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