SDSU Feedlot Research Summary
Paul Schlobohm, Research Associate
Faculty Supervisor: Dr. Robbi Pritchard

The renovated feedlot includes 70 concrete pens for cattle and eight larger dirt pens for cattle. There are also up-to-date cattle processing facilities as well as feed processing and storage facilities. Cattle are purchased as needed for research trials in beef nutrition and feedlot management.

CM9620. Mycogen Seed has developed a corn variety for the purpose of corn silage production. This genetically engineered variety has been tested for its agronomic properties, but its feed value for ruminants is unknown. We produced 200 T of this new variety and 200 T of our usual corn variety and stored the two silages in bunker silos.

They are being used as the basis of background diets fed for 80 days to 160 calves (10 pens/variety). Production variables of the 550 lb calves (ADG, DMI and F/G) will be used to assess feed value. Refinement of nutrient characteristics will be completed by thorough laboratory screening of these silages.

RP9610. The dietary guidelines for meeting the CP requirements of steers gaining over 3.5 lb/d are vague. We presume that they require protein enriched diets, but we do not want to feed excess CP that can add to waste problems. There is evidence that small amounts of dietary proteins that escape rumen degradation may be able to replace greater amounts of CP sources commonly used in feedlots. Usefulness of these rumen escape proteins may be affected by base diet ingredients. Yearling steers are being fed one of two base diets in that diets do or do not contain wet corn gluten feed, a common feeding by-product of the corn milling industry. Supplements added to these diets are either high urea content products typical of feedlot diets or low urea content products. Small amounts of rumen escape protein sources are included in half of these specially prepared liquid supplements. The effects of these diets on production efficiencies and carcass traits are being evaluated in 160 steers that weighed 750 lb when placed on feed. Expected time on feed is 120 days.

KB9660. The most important determinants of beef carcass value are external fat content and intramuscular fat deposits (marbling). External fat lowers value while marbling increases value. Previously we have assumed that external fat was necessary as evidence that marbling was present. We are beginning to realize that in reality there is a very weak relationship between these variables. We are also learning that EPD might be useful for identifying cattle that will produce lean carcasses with ample marbling. Before commercial cattle feeders can take advantage of this potentially valuable knowledge, we must learn more about when and how marbling develops. To do this we have identified high and low marbling EPD progeny groups of known age and parentage. These steers are being fed high grain diets typically used in feedlots. Subjects will be harvested when weighing 700, 850, 1000, 1150 and 1300 lbs. Intramuscular fat cell development and metabolism and body composition will be studied at each stage of growth. These data will be used to help cattle feeders optimize diets, implant strategies and market weights of cattle.

WC9650. Late springs often delay crop plantings in this region. It is difficult to find crops suitable for planting after June 10. In previous studies we found immature corn caused by early frost had little cash market value but was in fact an excellent feed for cattle. It is possible that immature corn caused by late planting may also be a suitable feed for cattle. If so, this would be beneficial to farm-feedlot operations seeking to optimize economics of both the cattle and land enterprises. To test this concept, 20 varieties of corn were planted in June 1996. These plots were harvested to determine yield data. The grains are being evaluated by laboratory analysis and in vitro digestion studies for feed value. We hope to be able to identify varieties that can be used in the future as suitable for late planting to produce grain for cattle.

Last Modified: August 02, 2006