SEQUENCING OF FEED INGREDIENTS FOR RATION MIXING

J. J. Wagner⁽¹⁾
Department of Animal and Range Sciences

CATTLE 95-14

Summary

Alternative methods of sequencing ration ingredients into a mixer wagon were evaluated using a 13.53% roughage finishing diet. Batches A and B evaluated the addition of grass hay to a triple auger mixer either last or first, respectively. Batches C and D examined adding liquid supplement to a reel type mixer either immediately after the addition of corn or first, respectively. Three samples were obtained from each batch after 2, 4, 6 and 8 minutes. The coefficient of variation among acid detergent fiber levels at each time period for each batch was used as the criterion for determining adequacy of mix. Both batches A and B appeared adequately mixed after 6 minutes, indicating that ground grass hay could be added to a finishing diet either first or last when using a triple auger mixer. Batch C appeared adequately mixed after 4 minutes. Coefficients of variation for all mixing times were larger for batch D as compared to batch C at all mixing times, indicating that adding liquid supplement to the batch first may result in a poorer ration mix than adding liquid supplement immediately after corn.

Key Words: Mixer Wagon, Ration Quality Control

Introduction

Ration quality control is an important component of feedlot management. Providing cattle with a properly formulated and mixed diet is critical in maintaining stable feed intake patterns and optimum performance. Previous research conducted at South Dakota State University has demonstrated that optimum mixing time should be determined for specific rations and mixer wagons.

Presumably, the sequence in which feeds are added to the mixing equipment also affects mixing adequacy and time. Generally, the major feed commodities are added to the mixer in order from most dense to least dense. One objective of this research was to evaluate whether ground hay should be added to a finishing diet first or last when using a triple auger mixer (TRA). Another objective was to determine if liquid supplement could be added to a finishing diet first when using a reel type mixer (RT).

Materials and Methods

Table 1 shows the ingredient and theoretical nutrient composition of the finishing ration used in this study. For the TRA mixer², the feed ingredients were added in the following order: Batch A - corn, liquid supplement, soybean meal, hay; Batch B - hay, corn, soybean meal, liquid supplement. For the RT mixer³, the feed ingredients were added in the following order: Batch C - corn, liquid supplement, soybean meal, hay; Batch D - liquid supplement, corn, soybean meal, hay. For batches A and C, liquid supplement was distributed evenly across the top of the corn. The liquid supplement was then mixed into the corn for about 30 seconds. The mixers were then stopped and the remaining ingredients added. For batch D, liquid supplement was added to the empty mixer. Then corn was added to the batch. The corn was mixed into the supplement for about 30 seconds. The mixer was then stopped and the remaining ingredients added. For batch B, all feed ingredients were added to the mixer without any 30-second premix periods.

Once the last ingredient was added, the mixer was started and allowed to run for 2 minutes. The mixer was then stopped and a two quart sample was obtained off the top of the mixture from the front, middle and back of the wagon. The mixer was started again and stopped at 2-minute intervals and additional samples were obtained at each interval. Thus, three samples were obtained after 2, 4, 6 and 8 minutes of mixing. Samples were analyzed for dry matter, crude protein, acid detergent fiber (ADF), and ash according to standard wet chemistry procedures. ADF values were reported on an ash free basis.

Samples collected from the front, middle and rear of the mixer were considered replicates 1, 2 and 3 at each time period. Mean values were calculated at each time period and the coefficient of variation was used as a criterion to determine adequacy of mix.

Results and Discussion

Table 2 shows the mean and the coefficient of variation for each time period for batches A and B. Table 3 shows the mean and the coefficient of variation for each time period for batches C and D. The coefficients of variation observed for dry matter content and crude protein were generally small and of limited value in evaluating mixing adequacy.

ADF values were much more variable among ingredients and are more useful in evaluating ration mix. For the TRA mixer, both batches appeared adequately mixed after 6 minutes. Additional mixing beyond 6 minutes appears to increase ADF variation and may indicate a breakdown in the ration mix. All values reported for ADF appeared greater than the theoretical value. For batch A, this may be due to adding the highest ADF feed last to the mix. It may be more difficult to obtain a uniform mix from top to bottom in the mixer. However, for batch B it is not clear why the ration at the top of the mixer should be higher in ADF content.

For the RT mixer, batch C appeared adequately mixed after 4 minutes. The coefficient of variation declined from 17.72% to 6.43%. Batch D appeared to be mixed more slowly. The coefficient variation didn't decline to below 10% until 8 minutes of mixing. Much higher coefficients of variation were observed at all mixing times for batch D as compared with batch C, indicating that adding liquid supplement first to the RT mixer resulted in a poorer ration mix.

Often the sequence of ingredients selected to add to the mixing equipment is based on convenience. It may be desirable to add one commodity first or last to the mix based on location of that feed relative to the other feeds. The data presented in this paper suggest that adequacy of ration mix can be affected by the sequence of adding feeds to the mixer. Adequacy of mix should be a major criterion for selecting the sequence used for feed mixing.

Acknowledgements

The author wishes to thank Sioux Automation of Sioux Center, IA, for providing the mixers used in this study.

1. Associate Professor.

²Oswalt triple auger mixer.

³Knight reel augie mixer.

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Modified: December 03, 1997