Pasture-Based Beef Finishing Systems

The summer pasture season was divided into two phases because the gains were not as good as expected early in the grazing period (Table 2 and 8). During the 1995 summer period there was only .25 lb ADG difference between treatments 0% and 75% grain supplementation. In 1996 this difference was 1 lb ADG, which is in line with expectations. We again obtained lower then expected gains early in the 1996 grazing season and as a result added soybean hulls to the supplementation mixture in phase II of 1996 to prevent acidosis and promote appetite. We also increased the supplementation levels to increase the total energy intake of the steers. Also the steers were given a fresh paddock of pasture daily to promote pasture intake. These changes seemed to be successful because the steers had improved appetites in phase II and the ADG's were improved (Table 8). Phase I was approximately100 days in length and phase II was approximately 75 days.

The gain response of cattle being supplemented on pasture is an interaction of pasture DM available, supplementation leve, and stocking rate. During these trial periods we did not get the expected gains of the steers as would be expected from the amount of energy and other nutrients being consumed by the cattle. The lack of gain from the 50% and 75% grain levels may have been due to the steers’ fescue pastures being 90% infected with endophyte. Another reason for depressed gains may have been the use of relatively high levels of corn gluten feed in the supplement mixtures and the resulting high level of rumen degradable protein consumed by the cattle.

Tables 3 and 9 contain the average values for final live weight, and carcass weight of the steers as well as the dressing percent. As carcass weight increased, the dressing percentage increased because of the higher level of finish. It is well known that more highly finished cattle have higher dressing percentages than lean cattle. In the marketplace, the steers with the small carcasses were discounted more than $20 cwt of hanging weight.

The carcass quality measurements are shown in Tables 4 and 10. In general, all quality measures increased as grain level increased and trend of change with increased grain supplement feeding were similar for both 1995 and 1996. Slightly over 90% of the carcasses in the feedlot group graded choice, whereas 14 of 16 steers on the 0% supplement treatment graded Standard with 2 grading Select. In the market the Standard carcasses were discounted severely so that there value was $220 less than the feedlot steers. With as little as 45 days in the feedlot or full grain feeding on pasture, these cattle would have probably graded similar to the feedlot group and the carcass value would have also been similar. We can report this with confidence because we have done it with other groups of cattle.

Fat color was also evaluated by giving each carcass a subjective visual score of 1 to 5, with 1 being the lightest color, as it hung in the cooler. Pasture finished cattle have been reported to have yellow, undesirable fat. The fat of the cattle on this study did not have yellow fat (Table 4).

Profit and loss values have been calculated (Table 14). Cost of gain for the pasture treatment and 0% supplement level was lower than the treatments where grain supplement was used. One of our goals was to produce finished cattle from pasture with as little as 1500 to 2000 lb of grain. The findings of this study indicate that such a goal is realistic. Costs of finishing beef in these systems would depend upon the cost of grain and pasture. The values in Table 4 indicate that cattle can be finished for from $35 to $45 per cwt weight of gain in these systems when grain prices are relatively moderate These costs of gain would be very competitive.

Short strip loins were taken from six steer carcasses from each replication (a total 48 loins) and were frozen. These KC strip steaks were subjected to sensory (both descriptive and acceptability) tests, tenderness tests, and biochemical flavor analysis (Table 5,6,11). These tests have given much needed information about the seriousness of off flavors in pasture finished beef and the potential for preventing any problems by using grain supplementation.

Beef Acceptability Comparisons: We conducted three major acceptance comparisons (tabular data not included in this report) where three strip loins were cooked in similar conditions. The three treatments used have been Feedlot, 75% grain, and 0% grain. These cooked meats are served to people in a banquet setting and they are asked to rank their preferences. The comparisons involved 147 people. The respective average ranking scores were 1.82, 2.06, and1.98, which indicated that these meats were all acceptable and people could not tell the difference between treatments. These sensory evaluation groups were our advisory board and groups of grass farmers. These sensory evaluations were very popular as well as educational.

Sensory analysis of beef: Forty-eight strip loins of beef were analyzed for sensory descriptive analysis and sensory acceptance analysis (Table 5 and Appendix 2 and 3). The following are some summary statements from the report.

"Although there were significant differences among the steaks in the Consumer study, all of the steaks were rated at or above "Neither like nor dislike" on the 9-point hedonic scale, thus on average, none of the steaks were disliked. Differences were found among the categories in both the descriptive analysis and the consumer acceptance analysis. When considering the results from both studies, the information leads to the conclusion than some grass feeding of beef may be possible without detrimentally affecting steak quality. Since several of the significant descriptive analysis attributes were textural, it would also be important to consider other factors contributing to steak texture, such as pre- and post-slaughter conditions. Some data for sensory and tenderness comparisons among the treatments are presented in Table 5 and for analysis of chemical compounds are presented in Table 6. These data indicate that a lack of tenderness is the major shortcoming of pasture finished beef.

In 1996 a comparison was conducted to determine the effect on tenderness of aging the beef in vacuum packed cold storage for 1, 3, and 5 weeks (appendix 3). We found that aging the beef for 3 weeks resulted in tenderness comparable to feedlot finishing. Since beef can be vacuum packaged and shipped in boxes, it is very feasible that this process could be incorporated into conventional processing and marketing systems.

Pasture measurements: Clipped quadrant samples of pasture were taken before and after paddocks were grazed to measure pasture forage available and forage disappearance. Pastures were intensively managed, cool-season grass-legume pastures as indicated by the stand counts that were collected in both 1995 and 1996. Forage voluntary intake and forage dry matter available are presented in Table 7. Forage dry matter intake improved through the season, with crude protein content increasing and acid detergent fiber (ADF) content decreasing (American Forage and Grassland Proceedings, 1996, appendix 4, publications). Forage intake decreased at an average rate of 1 lb for each pound of grain fed. Observed average daily gains were consistent with predicted ADG based on forage plus grain intake levels. Forage quality tended to increase throughout the grazing season on all treatments. Forage availability at the beginning of each rotation remained near constant or slightly increased for the 0% and 25% grain groups, while availability tended to decrease slightly through the season for the steers receiving 50% and 75% grain levels. It appears that forage availability was more likely to limit steer performance than would forage quality on these mixed cool-season grass-legume pastures.

Soil measurements: Two paddocks in each treatment of each replication were laid off in grids marked by stakes in the ground. Each treatment within a replication of pasture paddocks had two gridded pastures for the collection of random soil samples. Soil samples were collected in spring 1995, spring 1996, and spring 1997 for analysis of soil nutrients - Phosphate, Potassium, pH, Neutralizable Acidity, Calcium, Organic Matter, and Magnesium. A summary of these data is shown in Table 13. Changes are shown for the two-year period of this study. Calcium increased with supplemental feeding in the upper three inches of soil but pH was not affected. This lack of change in pH may be due to the slowness with which calcium is ionized and affects pH over time. Organic matter, phosphorus, and potassium tended to increase at moderate levels in the upper six inches of soil during the 2-year study with the higher supplement feeding levels. On poor to moderate fertility soils, finishing cattle would be expected to benefit soil fertility levels and subsequent pasture production.