Understanding of Sire Differences in Feed Intake and Efficiency

May, Rebecca
Murdoch University


The following is a summary submitted with the application. It will be updated when the student’s abstract/thesis is received.

The primary objectives of this project are to: (i) quantify differences between sire groups feed efficiency in a feedlot under commercial conditions; and (ii) quantify differences between sire group in grazing behaviour and physical activity in a feed lot under commercial conditions.This project will be undertaken at the Katanning Research Facility between April and June 2019 using wethers form the 2016 drop born progeny from the Merino Lifetime Productivity (MLP) project in Pingelly. Data collection for this project will be taken form the feedlot phase of the project. During this phase, 160 wethers from 15 sires with known feed efficiency (determined in the indoor phase of the project) will be placed in a feedlot under commercial conditions. They will be fed for two months and weighed twice weekly. Feed intake will be estimated indirectly from CO2 production, dosing with indigestible external markers and NIR analysis of faeces samples and or from wearable motion sensors. CO2 production over 45 mininute will be measured using portable accumulation chambers on two occassions. The activity sensors will be amounted to a halter and will be fitted to each sheep for a period of 5 to 7 days on two occassions. The activity sensors will be used to assess motions that are associated with feed intake (ie. rumination and grazing time) and also the contribution of physical activity (ie walking standing and lying) to energy expenditure in the feedlot

The expected outcomes from this project will include an increased understanding of sire differences in feed intake and efficiency, how differences measured indoors relate to those measured in a feedlot environment, and the biological basis for these differences. This could lead to a greater understanding of the role of these traits in genetic selection programs and productivity per hectare. Ultimately, this could encourage and assist ram breeders in adjusting their breeding directions and commercial growers altering how they select their rams.