2006 Abstracts - American Society of Animal Science

82 Effect of stocking rate and corn gluten feed supplementationon the performance of young beef cows grazing winter stockpiledtall fescue-red clover. R. Driskill, J. R. Russell*, D. R. Strohbehn,and D. G. Morrical, Iowa State University, Ames.A winter grazing experiment was conducted to evaluate the BW andbody condition scores (BCS) of bred two-year old cows grazing stockpiledforage at two stocking rates and two levels of supplementationduring winter. Two 12.2-ha blocks containing ‘Fawn’ endophyte-freetall fescue-red clover were each divided into four pastures of 2.53 or3.54 ha. Hay was harvested from the pastures in June and August of2003 and 2004 and N was applied at 44.8 kg N/ha at the initiation ofstockpiling in August. On October 22, 2003, and October 20, 2004,twenty-four Angus-Simmental and Angus two-year old cows were allottedby BW and BCS to strip-graze for 147 d at 1.19 or 0.84 cow/haand eight similar two-year old cows were allotted to two dry lots andfed tall fescue-red clover hay. Corn gluten feed was fed to maintain meanBCS of 5 or 4.33 (9-point scale) for cows in the high and low supplementationlevels, respectively, or when weather prevented grazing. Meanconcentrations of CP in yr 1 and 2 and IVDMD in yr 1 were greater (P< 0.10) in hay than stockpiled forage over the season. At the end ofgrazing, cows fed hay in the dry lots had greater (P < 0.05) BCS in yr 1and greater (P < 0.10) BW in yr 2 than grazing cows. Grazing cows inthe high supplementation treatment had greater (P < 0.10) BCS (yr 1)and BW (yr 2) than cows grazing at the low supplementation level.Cows in the dry lot were fed 2565 and 2158 kg DM hay/cow. Amountsof corn gluten feed supplemented to cows in yr 1 and 2 were 46.2 and60.8 kg/cow and did not differ between forage, stocking rate or supplementationtreatments in either year. Estimated production costs weregreater for cows in the dry lots due to greater amounts of harvestedfeeds fed.Key Words: Beef cows, Stockpiled forage, Corn gluten feed83 The variance of residual feed intake in purebred Herefordheifers fed a forage diet. L.S. Miller*, M. S. Kerley, and W. H.Kolath, University of Missouri, Columbia.The primary emphasis in measuring gain efficiency of cattle has been inthe feedlot, with less emphasis on research evaluating the variationbetween females within a breeding herd. Therefore, the objective of thisexperiment was to determine the variation in residual feed intake of 42Hereford heifers. These heifers were acquired from 19 breeders in Missouriand represented approximately 70 separate cow lines. The heiferswere provided ad libitum alfalfa/grass hay for a period of 51 days duringwhich time individual animal intake was recorded using the GrowSafe®feed intake system. Residual feed intake values were calculated and usedas a phenotypic measure of efficiency. The five heifers with the lowestRFI values consumed 14.57 ± 3.89 kg/d while the five heifers with thegreatest RFI values consumed 27.20 ± 4.86 kg/d. When expressed as apercent of body weight (PBW), forage intake for the lowest RFI groupwas 2.50 PBW and for the highest RFI was 5.05 PBW. The efficiency ofgain differed between the lowest and highest RFI groups. There was nodifference (P>0.05) between groups in body condition score (averagebody condition score 5.5) or gain (0.74 kg/d vs 0.64 kg/d). Annuallyheifers with the higher RFI would consume approximately 4600 kgmore forage than the heifers with low RFI values. These findings wereconsistent with previous research conducted in our laboratory that foundintake of high RFI feedlot calves were greater than low RFI calves. Theselection for animals that have low RFI values should impact carryingcapacity of pastures.Key Words: Cattle, Feed efficiency, Intake84 Effect of barley particle size on intake, growth, and gainefficiency of steers fed growing diets. D. Larson*, M. Bauer, and G.Lardy, North Dakota State University, Fargo.A study was conducted to evaluate the effect of barley particle size ongrowth, intake, and gain efficiency of steers fed growing diets. Previousresearch indicates that more extensive processing of barley results inreduced DMI, increased ADG, and improved G:F ratio. One hundred,forty-four crossbred steer calves (initial BW = 334 ± 16 kg) were blockedby initial weight and assigned randomly to one of three treatments.Treatments consisted of barley (42.6%, DM basis) reduced to 1708(coarse-rolled barley, CRB), 1395 (medium-rolled barley, MRB), or1146 (fine-rolled barley, FRB) Μm, approximately 61, 50, and 41% ofwhole barley (2800 Μm), respectively, fed in a total mixed ration. Theration DM also contained pressed wet sugar-beet pulp (35%), choppedmixed hay (15%), concentrated separator by-product (5.0%), and asupplement (2.4%). Diets were formulated to provide 12.5% CP, 27.5mg/kg monensin, and 11 mg/kg tylosin. Calves were fed for 61 d, bodyweight was measured approximately every 28 d, feed intake was recordeddaily, and feed refusal was recorded weekly. Steers were implantedon d 0 of the trial. Data were analyzed using the MIXEDprocedure of SAS and mean separation by LSD along with linear andquadratic contrasts (P = 0.05). Body weight was similar (P = 0.39)between treatments at d 0 (334 ± 16 kg), d 29 (384 ± 16 kg), and d 61(430 ± 15 kg). Average daily gain (1.50 ± 0.03 kg/d) also did not differ (P= 0.19) among treatment groups. Dry matter intake (9.20 ± 0.33 kg) wassimilar (P = 0.23) across treatments. Apparent dietary NEm (1.83 ±0.03) and NEg (1.19 ± 0.03) were similar (P = 0.74) among treatments.Finally, G:F (0.163 ± 0.01) was not different (P = 0.92) among treatments.Although there were no differences, calves consuming the FRBdiet had a tendency to have greater DMI (P = 0.11) and ADG (P = 0.07)in a linear fashion when compared to those consuming the CRB diet. Weconcluded that under the conditions of this study, barley grain ground to1146 Μm appears to have equal feeding value to barley grain rolled to1708 and 1395 Μm in a growing ration.Key Words: Barley, Bovine, Particle size85 Effect of pulse grains on rumen fermentation, digestion,and microbial protein synthesis in receiving diets for beef cattle.T. Gilbery* 1 , G. Lardy 1 , S. Navarro 1 , M. Bauer 1 , and V. Anderson 2 ,1 North Dakota State University, Fargo, 2 North Dakota State University,Carrington.Abstract: Eight Holstein and 8 Angus crossbred steers (509 ± 137 kginitial BW) fitted with ruminal and duodenal cannulae were utilized in acompletely randomized design experiment to evaluate the effects ofpulse grain inclusion in growing diets on intake, ruminal fermentation,28