BunkScoring

Bunk Scoring Really Works

Clifton L. Willms, Ph.D., PAS

Land O' Lakes Farmland Beef team has worked with a number of producers to implement good bunk management practices. We have referenced much of the work by Dr. Robbi Pritchard to help producers be more profitable. While many producers know from first hand experience that bunk management is important to bottom line profitability, rarely do we see research trials demonstrating the value.

A trial conducted by Colorado State University and reported in ARPAS 16:182-187 (September 2000) demonstrates the value of good bunk management. Two of the treatment groups in the trial contrasted feeding rations with 7.5% corn silage (DM basis) either ad lib or at restricted (slick bunk management) intake. Whole-shelled corn was the grain source.

	The researchers used the same bunk scoring method proposed by Dr. Pritchard of SDSU (score from 0 to 4).
	The ad-lib bunk management protocol (control) called for a bunk score of 2 in the evening and 1 to 0.5 in the morning.
	The restricted bunk management protocol (slick-bunk management) called for bunk scores of 1 to 2 in the evening and a score of 0 in the morning. This strategy was expected to achieve 3 to 6% restriction of intake compared to the control treatment.
	Over the entire 173-d trial, the slick bunk management protocol reduced feed intake, did not affect ADG, improved feed conversion, and lowered feed cost of gain. There were some differences reported within 28-d weigh periods not discussed here.

	Ad – lib	Restricted
Feed intake, lb./d	21.12	20.22
ADG, lb./d	3.12*	3.12
Feed/gain	6.69	6.44
Feed cost of gain, $/lb.	.4545	.4409
* Discrepancy in manuscript. The value provided in the article (Table 5) is apparently in error. The value provided here is calculated from other data and consistent with the discussion. There are some rounding errors converting from metric to English units of measure.

	It appears that weigh-back feed was not considered in calculating feed cost of gain. Therefore, the real feed costs would be higher for the ad-lib treatment to account for this wastage.
	The authors noted that there were no differences in feed intake during the last period (141-173 d) after weigh-backs were accounted for. This implies to me that potentially cattle trained themselves to regular intake even though fed ad-lib, possibly in part due to the small number of head per pen. That does not always happen. My bias is that we have greater potential for larger swings in individual animal intake with ad lib feeding in a commercial yard setting.
	There were no differences in quality grade or yield grade. There was a tendency for a lower dressing percentage with the restricted intake cattle. No explanation was discussed.
	OM, DM and N digestibilities were improved 8, 2, and 4%, respectively with the slick-bunk management protocol.
	Based on 541 lb. total gain, the slick bunk managed cattle had $9.12/hd advantage in feed costs. (Value provided in the text by the authors. Due to rounding error converting from metric, the COG in above table does not calculate equal to this.)
	The trial also looked at using low quality roughage (ground corn stalks or millet hay) in diets fed ad-lib. There was a trend toward higher ADG and reduced intake with these forages. My bias is that this data was showing some effects due to effective NDF and should not be interpreted that one abandon slick bunk management with these forages. The application in my opinion is to pay attention to fiber levels when formulating finishing diets.