Research and Reviews: Beef and Sheep

Special Circular 170-99

Yeast-Mineral Mixes and Beef-Cattle Performance in Fescue-Based Grazing Systems: Preliminary Report

S. Boyles^{+ 1}, W. Shriver⁺⁺, and D. Kobs^+
+The Ohio State University Department of Animal Sciences
⁺⁺Eastern Ohio Resource Development Center

Abstract

Much of the eastern and southern United States has endophyte-infected fescue as the main source of forage protein and energy. Yeast products, such as Saccharomyces cerevisiae, may assist in digestion of forages. Based on regression analysis, gestating heifers appeared to gain slightly more weight if they had access to a free-choice mineral supplement containing yeast than a control mineral. Control heifers lost less weight during the interval of calving and peak lactation. However, this may have some relation to milk production differences. Cow-calf pairs consuming yeast-mineral mixes resulted in increased weaning weights.

Introduction

Much of the eastern and southern United States has endophyte-infected fescue as the main source of forage protein and energy. While new lines of endophyte-free fescue exist, it is unlikely that there will be wide-spread replanting of fescue areas. There is a renewed interest in year-round or extended grazing to reduce the feed cost of cow-calf production programs. Methods need to be developed to utilize the existing forage base. Yeast products may assist in digestion of forages. The yeast Saccharomyces cerevisiae is produced by fermenting selected liquid and cereal grain raw ingredients with bakers yeast. Yeast delivery by means of a mineral supplement to improve animal performance would be less labor intensive than replanting a vast acreage of pastures.

Yeast cultures have been shown to positively affect animal performance and mineral consumption. Trials in Florida and California resulted in improved feed intake, production, and reduced rectal temperatures during summer heat stress in dairy cattle (Harris and Lobo, 1988, and Higginbotham et al., 1994). Yeast cultures have also increased rumen bacteria numbers and improved the digestion of feedstuffs in both beef and dairy animals (Arambel et al., 1987; Arambel and Kent, 1990; Bernard and Kelly, 1992; Harrison et al., 1998). Both mineral consumption and absorption have been positively affected by the addition of yeast culture to free-choice mineral mixes (Higginbotham et al., 1994). A trial conducted in 1986 also showed improved weight gains in yeast culture fed cattle grazing fescue pasture (Williams, 1986).

The previously mentioned research evaluated mainly summer grazing or mechanically harvested forages. This project would be developed to investigate the use of yeast products throughout the year with varying qualities of forage. The objective was to evaluate the effect of yeast on cattle performance in fescue-based forage systems. These are preliminary results from the first year of a three-year study.

Materials and Methods

Animals

Forty Angus and Angus-Hereford heifers (761 + 60.2 lb) were used to evaluate the use of yeast-mineral mixes for grazing cattle. The heifers were weighed two days consecutively at the beginning of the trial and then divided into two uniform groups. One group of heifers was fed a mineral-containing yeast (Yeast) and the other received a mineral supplement without yeast (Control). Interim weights were obtained approximately every 36 days. Calves were also weighed at similar intervals. Hip height measurements were recorded approximately 30 days prior to calving.

Prior to the initiation of the trial in June, the heifers had been artificially inseminated. Melengestrol Acetate (MGA™) was fed with a grain carrier and top-dressed on the feed. The MGA™ was fed at a rate of 0.5 mg per head per day for 14 days. Prostaglandin was administered 17 days after MGA™ withdraw. Heifers were bred 12 hours after observed estrus behavior. Heifers not exhibiting estrus behavior were administered another prostaglandin injection 11 days after the first. To minimize sire effects, only semen from two bulls was used to breed the heifers. The sires were equally utilized in both groups of heifers. Pregnancy was determined by the birth of a calf.

Mineral Supplements

The mineral supplements that were utilized are listed here:

The base mineral mix was similar for both supplements. The yeast was added at a rate of 25%. Initial mineral and vitamin concentration was not similar but it was felt the variation in supplemental intake would equalize mineral and vitamin intake from treatment sources. Both of these mineral supplements are currently available as commercial mineral supplements.

Both yeast and control supplements were available free-choice. Supplements were weighed into standard mineral feeders. Supplement remaining in the mineral box deemed unsuitable for consumption was weighed and removed.

Research Site

A 90-acre parcel of ground was allocated for grazing. An additional adjacent 39.65-acre parcel was available for hay production. The site is predominantly unimproved Kentucky-31 tall fescue. Some red clover, orchardgrass, and bromegrass were present but were not seeded. The site has not recently received any lime or fertilizer. The forage management practiced on the site is typical of the region.

Forage Samples

Forage samples were collected on a bi-monthly interval. Samples were taken from a paddock prior to the cattle entering the grazing area. The procedure was to walk diagonally across the field and take small samples and place the collected forage in a sealable plastic bag. The samples were frozen and then sent to the Ohio State University Research-Extension Analytical Laboratory at Wooster for analysis.

Milk Production

Previous research in dairy cattle indicates that supplemental yeast can enhance milk production. All lactating heifers were evaluated for milk production approximately 60 and 120 days after calving. A weigh-suckle-weigh procedure was utilized. The calves were removed from the cows and only allowed access to their dams at eight-hour intervals during a 24-hour period. Calves were weighed immediately prior to and after suckling.

Results and Discussion

Animal Body Weight Change

Based on regression analysis, gestating heifers appeared to gain slightly more weight if they had access to a free-choice mineral supplement containing yeast than a control mineral (Table 2). There also appeared to be slightly more body-weight gain for the yeast- supplemented heifers compared to controls during early-spring grass growth. Control heifers lost less weight during the interval of calving and peak lactation. However, this may have some relation to milk production (Table 3).

Body Condition, Milk Production, and Weaning Weight

The period of calving, peak lactation, and rebreeding is a very critical time in the production stage of beef cattle. Body condition was critically evaluated during the months of April, May, and June. Body condition based upon pounds to inches in height was found to be similar between control and yeast-supplemented cattle (Table 3). All heifers had hip height measurements of approximately 50 inches in April. Milk production in May was 15.4 and 15.6 lb per day for control and yeast-supplemented heifers, respectively (Table 3). Milk production for heifers consuming the yeast-mineral mix appeared to be greater. Weaning weights and weight per day of age appeared to be improved by availability of a yeast-mineral mix.

Mineral Supplement Intake

Yeast inclusion increased total mineral supplemental intake (Table 4). Total supplemental mineral intake was 0.23 and 0.40 lb per day for the control and yeast-mineral, respectively. The yeast-mineral intake was 4.8 ounces per day, and the total yeast consumption per day was 1.2 ounces per day. The difference in total supplement intake between treatments was 0.19 ± 0.072 lb per day.

References

Arambel, M. J., Weidmeiere, A. D., and Walters, J. L. 1987. Influence of donor animal adaption to added yeast culture and/or Aspergillus oryzae fermentation extract on in-vitro rumen fermentation. Nutr. Rpts. Int. 35(3): 433—436.

Arambel, M. J. and Kent, B. A. 1990. Effect of yeast culture on nutrient digestibility and milk yield response in early to mid-lactation dairy cows. J. Dairy Sci. 73: 1560—1563.

Bernard, J. K. and Kelly, F. M. 1992. Production response of dairy cows to supplemental yeast culture during early lactation. University of Tennessee, Martin, Tenn. Diamond V Research Manual D9260.

Harris Jr., B. and Lobo, R. 1988. Feeding yeast culture to lactating dairy cows. J. Dairy Sci. 72 (Suppl. 1): 276 (Abstr.).

Harrison, G. A., Hemken, R. W., Dawson, K. A., Harmon, A. J., and Barber, K. B. 1998. Influence of addition of yeast culture supplement to diets of lactating cows on ruminal fermentation and microbial populations. J. Dairy Sci. 71:2967—2975.

Higginbotham, G. E., Collar, C. A., Aseltine, M. S., and Bath, D. L. 1994. Effect of yeast culture and Aspergillus oryzae extract on milk yield in a commercial dairy herd. University of California Cooperative Extension. J. Dairy Sci. 77:343—348.

Williams, J. E. 1986. Effect of yeast culture on weanling calves on fescue pasture. U. of Missouri, Columbia, Mo.