Measuring Feed Efficiency for Cows on Pasture

Background

The number one cost in cow calf production is feed, meaning that selecting feed efficient cows is important to reducing input costs. Although significant work has been done on measuring feed efficiency in feedlot settings, there are still challenges to measuring and identifying efficient animals when it comes to cows on pasture. While residual feed intake (RFI) works well in growing animals, cows tend to change their classification and re-rank when measured so it doesn’t work as well. Since cows consume high fibre, lower quality diets, variation in diet digestibility–or the ability of the animal to maximize nutrient absorption from these lower quality feeds, is likely underestimated in previous models developed on growing animals fed highly digestible diets.  Furthermore, individual cows may alter feed intake patterns to adapt these low-quality diets and maintain nutrient absorption.

Objectives

To determine the relationship of traditional feed efficiency measures to total track digestibility (TTD) and determine if that can be used to predict cow efficiency.

What they will do

Researchers are trying to find an accurate way to determine cow efficiency on pasture. 96 cows will be used in the trials. In the first experiment cows will be fed 25% straw 75% haylage diet ab libitum for 12 weeks. Cow weight and performance measures will be collected as well as intake and RFI. At the end of the feeding period cows will be measured for total track digestibility (TTD) correlations will be determined between RFI, TTD, methane emissions, and blood metabolites. In the second experiment the cows from the first trial will be re-evaluated for TTD with calves at side. In the third experiment cows will be fed either a high or low NDF diet and weight, performance measures, and TTD will be collected. To determine if TTD is a reliable method of measuring cow performance cows will be ranked as high, medium, or low TTD and it will be compared across experiments to see if it is repeatable.

Implications

Having a more accurate way to measure cow efficiency will help in future researchers as researchers try to figure out what makes some cows more efficient that others. If producers are able to identify which cows are more efficient they should be able to save money.