An experiment was conducted to determine the effects of soyhulls and Biosaf yeast (Saccharomyces cerevisiae) on feedlot performance during the receiving period of newly weaned calves. Two energy sources; corn and soyhulls were fed with or without Biosaf yeast (10g/hd/d). We utilized 154 head of newly weaned steer calves (BW=509 lb). Energy source had no effect (P>.10) on feedlot performance during the 35d receiving period. Inclusion of Biosaf yeast had no effect on feedlot performance during the 35d receiving period. Consequently, feed cost of gain ($/cwt) was identical for all treatments. Those results indicate soyhulls can replace corn in receiving diets if priced competitively. A longer receiving trial may be needed to detect difference in feedlot performance due to Biosaf yeast inclusion.

Starting newly weaned calves on feed can be very challenging. Cattle feeders can be faced with feed intake problems, health disorders, and digestive problems. The energy density of the diet as well as the amount of the diet fed can impact the feedlot performance during the receiving period (first 21 to 35d) and the overall health status of the cattle during that period.

Soyhulls are a co-product of soybean processing. Soyhulls represent the outer coating of the soybean. The energy density of soyhulls is quite high (77% TDN; .55 Mcal NE g/lb). However, there is little to no starch in soyhulls. The energy is derived from the highly digestible neutral detergent factor (NDF). Due to the low starch content in soyhulls, the inclusion of soyhulls in receiving diets should help alleviate metabolic disorders while maintaining adequate performance.

We utilized 154 head of predominately straight-Angus steer calves with an average initial weight of 509 lbs. These steers were newly weaned calves (within 36 h of going on test) from a ranch in Western South Dakota. This trial began November 3, 1998 and ended December 7, 1998 for a total of 35 days. These steers were randomly assigned to four treatments (Table 1).

Processing on day 1 included vaccinations for IBR, BRSV, BVD, PI₃, 7-way, Pasteurella and administered Dectomax pour-on for internal and external parasites. The steers were not implanted during this receiving trial.

Pens of steers were allowed to consume feed ad libitum. Pens were fed once daily beginning at 0830. The appropriate receiving diet (Table 2 and 3) was fed for the duration of the 35d-trial.

On test weights were recorded approximately 12 h after feedlot arrival. Steers had access to grass hay and water during this period. Forty-eight hours prior to completion of the trial all pens were placed on the soyhull diet (Table 2) to equilibrate the fill effects on final weight. The appropriate supplements (Table 3) were fed for the entire 35 d period. Water was removed the afternoon before going off test. Weekly samples of every ingredient (Table 2) of the diet were collected and frozen for lab analysis. Samples were ground and analyzed for bulk dry matter and Kjeldahl N (crude protein). Weekly samples of the supplements (Table 3) were analyzed for total viable yeast counts (Silliker Labs, MN).

Performance data (average daily gain, dry matter intakes and feed efficiency) were analyzed by procedures appropriate for completely random design experiments. Pen was considered to be the experimental unit. All statistical analyses were conducted using the GLM component of SAS.

Energy Source. Feedlot performance data is illustrated in Table 4. Energy source had no effect (P > .10) on feedlot performance during the 35 d receiving period. Numerically, steers fed corn-based diets gained 9.0% faster as compared to steers fed soyhull-based diets (2.40 vs. 2.20 lbs/d). It is interesting to note the expected NEg was 13% higher for the corn-based diets (Table 2). Although not illustrated in this report, feed cost of gain ($/cwt) was identical for all treatments.

Biosaf. Inclusion of Biosaf had no effect (P > .10) on feedlot performance during the 35 d receiving period (Table 4). Numerically, steers consuming Biosaf gained 4% faster as compared to steers consuming the control diets (2.34 vs. 2.25 lbs/d). Also, feed efficiency was improved numerically 5% with the inclusion of Biosaf (not significant).

The lack of significant differences in feedlot performance with Biosaf inclusion was difficult to explain. This experiment was only 35 d in length. It is plausible that the benefits of Biosaf on feedlot performance are not manifested in a 35 d period. In fact, communication with Saf Agri personnel would suggest that 21 d are needed to alter rumen fermentation. In this case only 14 d were left to affect growth rate and efficiency. A longer receiving trial (approximately 75d) may show positive results. Secondly, with any feeding trial, we are concerned about delivering the diet we formulated on paper. Table 5 illustrates the uniformity of mix of the four rations during this trial. Coefficients of variation (CV) less than 10% are often thought to be adequate. Our acid detergent fiber CV for the corn/Biosaf treatment was the only variable over 10% (Table 5). Finally, we analyzed weekly subsamples of the supplement for yeast counts. These results are illustrated in Table 6. Our theoretical target was 50 x 10⁹ CFU/hd/d. We observed an average intake of only 15 x 10⁹. As shown in Table 6, we experienced extreme variation in Biosaf intake during the trial. The entire supplement (Table 3) used in this trial was manufactured the last week of October 1998 in one batch. In fact, only during week 5 (Table 6) did Biosaf intake exceed the recommended level. This variation in Biosaf intake may be an artifact of testing error or random variation in mixing during the manufacturing of the supplement. However, the lack of response to feeding Biosaf in this receiving trial could be attributed to the extreme variation in weekly Biosaf intake.

This research was funded in part by SAF Agri, Minneapolis, MN. The authors also thank the staff at Southeast Research Farm for their support with this project.

Date last modified:  January 04, 2005