Maria Camila Londono-Mendez | ALES Graduate Seminar

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree. This is an ALES MSc Final Exam Seminar by Maria Camila Londono-Mendez. This seminar is open to the general public to attend.

Zoom Link: https://ualberta-ca.zoom.us/j/95945731019?pwd=yC6jo49TgPlzJ23gwDnrzhNeCjEPKa.1

MSc with Dr. Gleise Medeiros da Silva

Thesis Topic: Weather Resilience in Grazing Beef Heifers with Differing
Residual Feed Intake

Abstract: 

The beef industry seeks sustainability through improved feed efficiency, but the interaction between residual feed intake (RFI) and weather resilience in grazing beef heifers is underexplored. This study aimed to evaluated blood parameters, rumen temperature (RT), growth performance,
and activity behavior of beef heifers with varying RFI during summer and winter seasons in Western Canada. Forty-one crossbred beef heifers [351 ± 40 kg body weight (BW); 14 mo of age] were classified as more (LOW-RFI; n = 21, -0.96 ± 0.70) or less (HIGH-RFI; n = 20, 1.4 ± 1.00) feed-efficient. Heifer behavior was monitored using accelerometer-based sensors and individual non-fence collar technology. Rumen temperature and water intake frequency were monitored using a bolus device, and blood samples were collected to analyze parameters related to protein, lipid, and growth metabolism, as well as neurotransmitters and hormones associated with metabolic homeostasis. The neutrophil-to-lymphocyte ratio (N:LR) was also assessed as a marker of inflammation during winter. Environmental conditions were estimated by calculating the Climate Comprehensive Index. In summer, LOW-RFI heifers tended to exhibit greater free triiodothyronine levels (P = 0.08) and gamma-aminobutyric acid (P = 0.01) when weather was classified to impose moderate stress. The LOW-RFI heifers also tended to produce more heat shock protein 70 (P = 0.10), while HIGH-RFI heifers had greater haptoglobin (P = 0.02) concentrations. The RT was greater in HIGH-RFI heifers during specific hours of the day (P = 0.002). For activity behavior, HIGH-RFI heifers had a greater number of steps on certain days, sought shade and water spots during hotter days, and had more daily transitions. In winter, greater leptin concentrations were found in HIGH-RFI (P = 0.04), while GABA tended to decrease in HIGH-RFI heifers (P = 0.08). The LOW-RFI heifers had higher RT on certain days (P = 0.009), more standing activity during moderate cold stress, and higher N:LR on the coldest days. The HIGH-RFI heifers stood more on extreme cold days but had fewer steps on mild cold days and more steps on severe cold days. The LOW-RFI heifers had fewer daily transition times. There was no significant difference in growth performance between LOW and HIGH-RFI heifers (P > 0.24). Feed-efficient beef heifers in Western Canada exhibited greater potential for weather resilience to extreme conditions based blood parameters, rumen temperature, and activity behavior, without effects on growth performance. The LOW-RFI heifers displayed enhanced thermogenic activity during both summer and winter, although chronic cold exposure may have potentially negative consequences. These findings indicate the potential of selecting feed-efficient cattle for environmental resilience and supporting sustainable beef production. However, further research is necessary to understand the long-term impacts of chronic cold stress on LOW-RFI heifers.