The William H. Miner

Agricultural Research Institute

Miner Institute
Farm Report

FROM THE PRESIDENT'S DESK — CONSISTENCY AT THE FEED BUNK

What are the consequences of not having uniform feed delivery along the entire length of the feed bunk? The photograph that accompanies this article shows a situation where there are obvious differences in the amount of feed left in the manger. This situation of inconsistent feed availability is common. When we observe this situation where feed accessibility is limited, questions that spring to mind include: how long have portions of the bunk been empty? Does it affect some cows more than others? How does it affect feed intake and milk yield?

Another form of inconsistency at the feed bunk is when the quality of the feed delivered varies from one end of the bunk to the other. A recent study published in the Journal of Dairy Science (2013. 96:247-256) assessed the impact of variable diet quality at the feed bunk on feeding behavior of dairy heifers. In this study, the grain percentage was varied from 0 to either 24 or 39% of dietary dry matter (considered low, medium, and high quality). Heifers were offered various combination of the low, medium, or high quality diet in feed bins and their responses were observed for 15 minutes following delivery of fresh feed.
The researchers found that the heifers sampled the quality of the feed by changing their location (i.e. their feed bins) at the feed bunk continually during the observation period. In other words, they “grazed the feed bunk.” Heifers that were exposed to lower quality feed than previously experienced had a higher frequency of switches between feeding bins and a shorter time spent at each bin. The cattle continued to move along the feed bunk, sampling different bins, until they found a diet that they considered high quality (to their way of thinking that meant higher grain). Consider what this behavior would mean on a commercial farm where there is substantial variation in the quality and consistency of the feed being delivered along the length of the feed bunk. There would be considerably more cow movement and interactions at the bunk during that critical time period following feed delivery when feeding behavior is most intense.

In fact, this study found that non-uniform feed quality did increase competition at the bunk which simply reflected the heifer’s desire to access higher quality feed. Improving consistency in feed bunk management and feed delivered should reduce competition, minimize time that cattle spend moving up and down the length of the feed bunk, and assure that all cattle within a pen have similar opportunities to access the correct diet (i.e. the one so carefully formulated).
We can also take this research one step further. What is the added potential impact of individual cows not using the entire length of a feed bunk equally? Cows seem to have preferences for certain other cows – in essence, they form friendships and these cows can be consistently found together at the feed bunk and elsewhere in the pen. At Nebraska, we conducted some on-farm observations that indicated that cows seem to have preferred locations along a feed bunk – we never addressed the question in a systematic way, but this question needs an answer: Do cows use the entire length of the feed bunk equally regardless of feed quality? We also observed that when significant portions of the feed bunk became essentially empty then resting behavior suffered as well.

The bottom line is that diet quality at the feed bunk may vary over time of the day and along the length of the bunk depending on the farm’s management level. This variation has important effects on cattle feeding behavior and how successfully they will be able to optimize consumption of a well-formulated diet.

— Rick Grant

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The Miner Institute Farm Report is written primarily for farmers and other agricultural professionals in the Northeastern U.S. and Eastern Canada. Most articles deal with dairy and crops topics, but also included are articles dealing with environmental issues and global agriculture as well as editorial commentary.

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