Progress 07/01/06 to 06/30/08

Outputs
OUTPUTS: In beef production systems the weight of the animal is the single most important component in determining value. Thus, the ability to identify and propagate cattle that are efficient in converting feed into weight gain becomes an important component of a successful cow-calf unit. A one pound improvement in dry matter feed conversion of feeder calves reduces feed cost by $50 per head. Improved feed efficiency in cow-calf operations will reduce input cost and enhance profit potential for beef producers. Furthermore, the production of offspring is the driving force behind most cow/calf operations. Improved utilization of forage by beef cows, stocker cattle and steers and heifers in forage fed beef programs will provide additional economic impact and increase the number of animal units that can be produced per acre. From this project residual feed intake was determined utilizing the GrowSafe System in sire evaluations programs for beef bulls, rams, and bucks. Additionally, behavioral studies were conducted to determine feeding behaviors and perfomance measurements in bulls, rams and bucks. A study was conducted with beef heifers utilizing both the GrowSafe System and Heat Watch system to determine if differences in feed intake and behavior existed in association with estrus. PARTICIPANTS: Principle investigators Warren and Felton wrote the proposal, led the investigative work, analyzed and reported the data on the objectives of the project. Collaborators include Dr. Monty Kerley, University of Missour-Columbia, where calves utilized in pasture studies were fed to marked weight in the feed intake selecton experiment. West Virginia University Extension personnel provide leadership for organizing the sire evaluation programs and working directly with seedstock consignors and commercial producers buying seedstock from sales following the completion of the sire evaluation programs. This project has provided data for three Master of Science Theses (one completed and two in progress). TARGET AUDIENCES: Target audiences include livestock producers (beef, sheep and goat) who consign animals to the respective sire evaluation programs. As a result they obtain valuable data residual feed intake (RFI) for individual animals consigned and knowledge of performance of their animals relative to those of other consignors. Also, the RFI data is available and useful to commercial producers purchasing bulls, rams and bucks to use in their herds and flocks. Thus, overall feed efficiency may be improved which is the ultimate goal. Additionally, results of sire evaluations and experiment are shared through meeting proceedings, publication in scientific journals, and popular press articles with the scientific community and livestock producers both nationally and worldwide. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Six Angus bulls with known residual feed intakes (RFI) were used to breed three beef cow herds in the spring of 2005. Bulls were selected as pairs possessing similar expected progeny differences, growth performance but approximately equal but opposing RFI values. Forty-eight steer calves, 24 from +RFI sires(POS) and 24 from -RFI(NEG)sires, were selected based on similarity in bodyweight and winter growth performance and utilized for a pasture-season experiment and subsequent feedlot finishing. In the pasture experiment animal weight-gain and pasture forage disappearance/utilization measurements were collected. Results from measurements taken from the beginning of the experiment to late June (Period of excess forage) indicate that POS stocked pastures have more forage disappearance than NEG stocked pastures with no difference in animal performance. Results from late June to early August (Period of limiting forage) have not been fully analyzed but raw means show a 1.3 fold improvement in daily growth of NEG vs. POS steers. Steers were transported to the University of Missouri in mid October 2007 and worked up on full feed. All steers were treated equally and slaughtered in early February averaging an 832 lb carcass with a SM60 amount of marbling, 0.41 in of backfat, 13.0 sq. in. ribeye and a yield grade of 2.9. POS sired calves outperformed NEG sired calves by 0.57 lb/d over the 72 day finishing period with no difference in slaughter or hot carcass weight or standard carcass measurements. Although not statistically different, feed costs from the time steers entered the feedlot till slaughter averaged 21.63 dollars more per head for positive RFI sired steers. These results may indicate that when forage is plentiful, offspring sired by positive RFI sires are able to have a greater intake of energy than negative RFI sired offspring and therefore compensate for poorer metabolic efficiency yielding similar performance. However, under a limited forage environment, less efficient, positive RFI sired offspring are more likely to have poorer performance and create greater risk for the producer. The reduction in gain experienced by the positive sired offspring while on limited pasture allowed for them to have compensatory gain while finishing. However, the efficiency of the positive RFI sired steers was still compromised and resulted in them having an overall higher feed costs. These results are based on a limited number of offspring from six different sires, however results indicate that selection for RFI can be made with positive results. In analysis of feeding behaviors of rams, bucks and bulls in performance evaluation programs, more efficient animals generally have fewer feeding bouts than less efficient animals. Most feeding bouts occurred during the daylight hours for all species.

Publications

• Chavez,S., Baptiste Q., and Felton,E.E.D. 2008. Relationship between feeding behaviors in Boer bucks. Midwest Section American Society of Animal Science Meeting. DeMoine, IA. March 17-19,2008. Abstract 7,P.19.
• Chavez,S., 2008, Feeding behaviors and performance measurements in bucks, rams and bulls. Master of Science in Animal and Nutritional Sciences Thesis, West Virginia University, Morgantown, WV.
• Gulas,J., Warren,J, and Felton,E.E.D. 2008. Residual feed intake as a measure of feed efficiency of beef bulls in a test station. JAS-accepted with revision.
• Felton, Gene, 2008. Effects of resdiual feed intake selection:from conception to slaughter. Proceeding of Beef Research and Teaching Farm Field Day, University of Missouri-Columbia. Sept. 2008.

Progress 07/01/06 to 06/30/07

Outputs
Six Angus bulls with known residual feed intakes (RFI) were used to breed two West Virginia University (Wardensville and Reedsville) and one private producer's beef cow herds in the spring of 2005. Bulls were selected as pairs possessing similar expected progeny differences, growth performance but approximately equal but opposing RFI values within the test groups in which they were determined. Forty-eight steer claves (24 from +RFI sires and 24 from -RFI sires) from these three herds were selected based on similarity in bodyweight and winter growth performance and utilized for a pasture-season experiment beginning March 30, 2007 and is still ongoing. In this experiment, steers were allotted to 1 of 4 treatments, with treatment group being randomly assigned to 1 of 4, one-hectare plots (subdivided into 4 subplots for rotational grazing) located in 3 areas of differing terrain (bottomland, slight slope, and steep slope). Thus, steers were stocked at a rate of 4 hd per hectare with 4 treatments equally represented within each terrain classification. Based on 4 yrs of previous experiments on these sites utilizing this approach, with similar stocking rates, no interaction between terrain and treatment have been identified and would not be expected. Treatments tested were 4 positive RFI steers per pasture (POS), 4 negative RFI steers per pasture (NEG), 2 positive RFI steers per pasture lead grazing with 2 negative RFI steers follow grazing (+/-), and 2 negative RFI steers per pasture lead grazing with 2 positive RFI steers follow grazing (-/+). Animal weight-gain and pasture forage disappearance/utilization measurements are being collected. Data is being analyzed as two separate experiments: Experiment 1, POS vs. NEG, Experiment 2, +/- vs. -/+. Statistically analyzed results from measurements taken from the beginning of the experiment to late June (Period of excess forage) indicate that POS stocked pastures have more forage disappearance than NEG stocked pastures with no difference in animal performance. There was also no difference in pasture disappearance between +/- and -/+ stocked pastures. Although not significant, numerical differences in gain indicate that negative RFI sired steers are better able to utilize material left by forward grazed positive sired steers while no difference was seen in weight gain when positive RFI sired steers followed negative RFI sired steers. Results from late June to early August (Period of limiting forage) have not been fully analyzed but raw means show a 1.3 fold improvement in daily growth of NEG vs. POS steers. Raw means of the -/+ vs. +/- treatment showed similar better use of forage as seen in the earlier period with 1.6 fold greater ADG. These results may indicate that when forage is plentiful, offspring sired by positive RFI sires are able to have a greater intake of energy than negative RFI sired offspring and therefore compensate for poorer metabolic efficiency yielding similar performance. However, under a limited forage environment, less efficient, positive RFI sired offspring are more likely to have poorer performance and create greater risk for the producer.

Impacts
In beef production systems the weight of the animal is the single most important component in determining value. Thus, the ability to identify and propagate cattle that are efficient in converting feed into weight gain becomes an important component of a successful cow-calf unit. A one pound improvement in dry matter feed conversion of feeder calves reduces feed cost by $50 per head. Improved feed efficiency in cow-calf operations will reduce input cost and enhance profit potential for beef producers. Furthermore, the production of offspring is the driving force behind most cow/calf operations. Improved utilization of forage by beef cows, stocker cattle and steers and heifers in forage fed beef programs will provide additional economic impact and increase the number of animal units that can be produced per acre.

Publications

• No publications reported this period