3.- MATERIALES Y MÉTODOS
GLICINA 2.00 MIO-INOSITOL 100.00
The objective of the winter grazing study was to evaluate corn distillers dried grains with solubles (CDDGS) supplementation of August-calving cows or calves grazing
stockpiled forage on cow and calf BW changes during winter and BW gain and carcass characteristics of the calves finished in a pasture-based system. As expected, the results showed that over the 2 winters, calves in the Creep treatment had greater BW gains than calves in the CDDGS and Minimal treatments. However, the economic analysis showed that if calves were sold at weaning, greater net profit was achieved with the minimal
supplementation regimen. The increased BW gains were not sufficient to overcome the cost of the additional supplementation. Cows supplemented with CDDGS during the winter had decreased BW losses during winter, but the additional BW losses in the Minimal and Creep treatments had no noticeable detrimental impact on the breeding or economics of the herd.
Also, cows in the Minimal and Creep treatments regained BW while on pasture in the spring at a lower cost than the winter supplementation. As a result, it was overall more profitable to supplement minimally to cows and not supplement calves during winter grazing. As the economic analysis was based on not changing the stocking rates, and the metabolism trial indicated that the stocking rates could be increased by 20% with supplementation, perhaps this would alter the economics analysis.
This study also contained a pasture-based finishing portion where steers were
supplemented with CDDGS. It was observed that the post-weaning ADG of steers from the Minimal and CDDGS treatments were greater than steers fed a CDDGS-based creep feed pre-weaning. The literature suggests that it is not uncommon for steers on differing
nutritional planes to equilibrate as they approach finishing BW, and this phenomenon is often referred to as compensatory gain (Owens et al., 1993; Drouillard and Kuhl, 1999). This increased gain by the lighter steers at weaning resulted in mean live weight and carcass weights, backfat thickness, ribeye area, and marbling score at harvest that did not differ between treatments. While in this study we did not observe differences in the above
mentioned carcass parameters, and one could argue that the lack of differences may in fact be a result of the limited number of steers in the study. While nothing can be done at the present to address this concern, it would be potentially be of value to repeat the study with more
animals to either validate the results or to refute them and provide information as to which carcass parameters are affected with such a feeding regimen. Under the circumstances above, the economic analysis indicated that providing August-calving cows or calves grazing stockpiled forage with minimal supplementation during winter resulted in greater net profit when steers were sold at harvest than supplementing CDDGS to either cows or calves during winter at equal stocking rates.
A metabolism study was conducted simultaneous to the grazing experiment to
evaluate the effect of CDDGS supplementation of cattle fed smooth bromegrass hay on total DM and hay intake and diet digestibility. It was observed that increasing the amount of CDDGS supplement fed increased total DM intake as a percentage of BW and digestibility as a percentage, but decreased hay DM intake as a percentage of BW. This increase in DM intake and simultaneous decrease in hay DMI resulted in a quadratically increasing
substitution rate of CDDGS for smooth bromegrass hay with increasing CDDGS supplement intake as a percentage of BW. The maximum substitution rate of 0.53 kg forage DM intake for every kilogram of CDDGS DMI occurred when CDDGS were supplemented at 1.07%
BW. This substitution ratio means that at ad lib intake of forage and CDDGS fed at 1% of BW steers will replace about 0.5 kg of forage with 1 kg of CDDGS. Increasing inclusion of CDDGS in the diet resulted in quadratic increases in the digestibilities of dietary DM, NDF, and CP and the concentrations of DE and ME which may be associated with the fat content of CDDGS. But in spite of effects of CDDGS on nutrient digestion, the effects on
supplementation on total DMI resulted in linear increases in the intakes of digestible DM, metabolizable energy, and crude protein. The metabolism study results imply that
supplementation of grazing cattle with CDDGS can be used to increase diet digestibility while reducing forage intake. This increase in diet digestibility and reduction in intake could be valuable under several circumstances including pasture shortage for a number of reasons, decreasing cost of CDDGS making it an economical substitute for pasture forage, or when increasing stocking rates is desirable. Under conditions where it is desirable to substitute CDDGS for hay as an energy source it may be necessary to be able to limit hay or forage intake so that the supplementation results in extension of pasture acres and not simply increased overall intake of energy.
72
Year 1 Year 2 Significance
Day mean Intercept Day mean Intercept Day mean (Intercept)
Mass Model Year Block TRT Graze TRT*GRZ
Ungrazed -5.93 (3.55) 3633.8 (521.2) -5.93 (3.55) 2529.2 (109.7) 0.0036 0.1548 0.1641 0.735 0.0001 0.474 Grazed -13.61 (3.57) 3633.8 (521.2) -13.61 (3.57) 2529.2 (109.7) (-0.017) (-0.002) (-0.283) (0.671)
ADF Ungrazed 0.904 (0.018)
35.84 (0.983) 30.34 (1.175)
0.0739 0.1382 0.5037 0.7736 0.0129 0.104
Grazed 0.108 (0.015) (0.001) (0.0001) (0.19) (0.870)
NDF
0.173 (0.015) 55.34 (2.23) 0.101 (0.022) 54.74 (2.49) 0.0001 0.0001 0.5962 0.9358 0.1256 0.916 (0.2399) (0.6246) (0.0496) (0.5777)
CP
0.004 (0.006) 9.08 (1.15) 10.31 (1.123) 0.4916 0.2245 0.08 0.5445 0.6962 0.905
(0.299) (0.108) (0.2315) (0.6547) ADIN
0.04 (0.03) 17.03 (2.97) 6.46 (0.909) 0.8692 0.2978 0.5226 0.881 0.758 0.595
(0.0006) (0.0001) (0.258) (0.315) IVDMD
Year 1 55.65 (0.99) 0.0001 0.0001 0.0343 0.067 0.006 0.434
Year 2 56.65 (2.11) (0.470) (0.330) (0.550) (0.346)
Ungrazed -0.134 (0.043) 56.2 (1.65) Grazed -0.112 (0.029)
APPENDIX A. EFFECTS OF WINTERSUPPLEMENTATION ON FORAGE PARAMETERSDURING WINTER STOCKPILED GRAZING
73
Cow BW(kg) Cow BCS Calf BW
Initial Final Change Initial Final Change Initial Final Change ADG
Treatment Min 677a 620 -57a 6.2a 4.6a -1.64 132 258a 127a 0.94a
Creep 681a 622 -59a 5.9b 4.7ab -1.35 130 317b 188b 1.40b
CDDGS 660b 634 -25b 6.1ab 4.9b -1.35 135.5 281a 146c 1.08c
SE 6.89 16.2 13.3 0.06 0.06 0.087 12.9 15.7 6.4 0.05
significance TRT 0.011 0.39 0.019 0.052 0.040 0.11 0.81 0.005 0.0001 0.0001
Year 1 Min 679.6 625.2 -54.3 6.04 4.47 -1.58 126.3 244.0 119.2 0.89
Creep 681.7 628.0 -53.7 5.75 4.71 -1.05 130.3 317.6 187.3 1.40
CDDGS 667.0 656.7 -10.3 6.13 4.96 -1.17 129.3 278.7 149.4 1.12
Year 2 Min 673.9 614.2 -73.3 6.33 4.67 -1.69 138.1 272.0 133.8 0.99
Creep 679.4 615.6 -63.8 6.08 4.69 -1.65 129.8 317.9 188.1 1.39
CDDGS 652.2 611.7 -40.5 6.04 4.81 -1.54 141.8 283.9 142.1 1.05
SE 9.74 22.95 18.75 0.08 0.09 0.12 18.3 22.3 9.0 0.07
significance Year 0.088 0.044 0.081 0.042 0.993 0.016 0.291 0.234 0.456 0.660
APPENDIX B. EFFECTS OF CDDGSSUPPLEMENTATION ON COW BW, COW BCS, ANDCALF BW OVER THE WINTER GRAZING SEASON
74 APPENDIX C. FORAGE AVAILABLE OVER THE SUMMER GRAZING SEASON
(kg/100kg BW) Year 1
Apr May June July Aug Sept Oct Nov Dec*
Pasture Trt
1 Creep 14.9 9.9 15.0 12.7 12.0 6.8
2 CDDGS 7.1 10.4 13.1 8.0 9.0 5.5
3 Min 13.0 14.8 15.9 14.9 12.4 8.8
5 Min 16.4 16.1 15.6 15.2 6.6 4.3
6 Creep 8.3 10.3 13.8 13.7 8.2 5.4
7 CDDGS 8.9 9.8 10.9 12.4 6.6 7.8
Average 14.1 25.4 21.5 11.4 11.9 14.0 12.8 9.1 6.4
Year 2
Apr May June July Aug Sept Oct Nov Dec*
Pasture Trt
1 Creep 15.3 13.3 10.7 11.2 7.3 6.7
2 CDDGS 11.3 8.9 9.2 9.2 4.6 4.6
3 Min 9.8 9.1 8.3 8.5 5.9 5.3
5 Creep 10.4 7.8 8.2 7.2 4.4 3.2
6 CDDGS 12.1 9.0 9.1 6.8 4.6 3.9
7 Min 11.7 9.5 9.7 8.3 5.3 4.4
Average 19.0 19.5 11.8 9.6 9.2 8.5 5.4 4.7
*Value after steer removal from pastures
75
76
Year 1 Year 2 P=
Mean Min DDG Creep Min DDG Creep SE Trt Yr Trt*Yr
Days in feed lot 51.5 72.5 41.0 72.5 41.0 41.0 41.0 6.6 0.10 0.01 0.10 (d)
HCWT 360.8 340.1 360.4 368.1 357.1 371.3 367.8 14.4 0.40 0.47 0.83 (kg)
FAT COVER 1.1 0.8 1.1 1.0 1.2 1.2 1.2 0.1 0.61 0.07 0.55
(cm)
% KPH 2.2 2.1 2.3 2.2 2.2 2.4 2.4 0.1 0.15 0.21 0.82
(%)
REA 81.1 79.5 78.4 81.3 80.2 85.2 81.8 2.2 0.65 0.20 0.35
(cm2)
marbling score 3.2 2.8 3.5 3.3 2.9 3.3 3.2 0.3 0.18 0.66 0.81
% Choice 65.3 58.5 75.0 62.5 50.0 75.0 71.0 17.2 0.52 1.00 0.89 (%)
YG plant 2.2 2.0 2.4 2.3 2.3 2.3 2.1 0.2 0.61 0.77 0.30
APPENDIX E. EFFECTS OF CDDGS SUPPLEMENTATIONON CARCASS CHARACTERISTICS
77 APPENDIX F. NET RETURNS AND SENSITIVITY ANALYSES OF AUGUST CALVES
FROM DIFFERRENT WINTER SUPPLEMENTATION TREATMENTS THAT WERE SOLD AT WEANING OR FINISHED IN A PASTURE-BASED SYSTEM
aYardage includes drylot (average 29d) post-weaning and time in feedlot(average 51.5d)
Steers retained through finishing Calves sold at weaning
Minimal Creep CDDGS Minimal Creep CDDGS
Revenue subtotal 1,531.15 1,574.15 1,583.18 1,019.11 1,077.28 1,086.31
Net Return 190.56 146.27 143.49 198.64 143.99 179.55
Sensitivity Analysis on Net Returns
Variable Steers retained through finishing Calves sold at Weaning
Labor +20% 147.70 97.73 90.63 172.86 112.06 144.41
APPENDIX G. COMPOSITION OF FREE CHOICE TRACE MINERAL AND VITAMIN PREMIX
Component Max Min
Calcium 18.3% 15.3%
Phosphorus 8.0%
Salt (NaCl) 16.2% 13.5%
Magnesium 1.0%
Potassium 0.15%
Copper 1,450 ppm
Manganese 4,950 ppm
Selenium 26.4 ppm
Zinc 4,750 ppm
Vitamin A 380,000 IU/lb
Vitamin D3 100,000 IU/lb
Vitamin E 375 IU/lb
Kent Framework 365 Mineral ADE
REFERENCES
Abdalla, H. O., D. G. Fox, and M. L. Thonney. 1988. Compensatory gain by Holstein calves after underfeeding protein. J. Anim. Sci. 66:2687-2695.
Adams, D.C., R.T. Clark, S. A. Coady, J. B. Lamb, and M. K. Nielsen. 1994. Extended grazing systems for improving economic returns from Nebraska sandhills cow/calf operations. J. Range Manage. 47:258-263.
Allen, V. G., J. P. Fontenot, D. R. Notter, and R. C. Hammes, Jr. 1992a. Forage systems for Beef Production From Conception to SlaughterI. Cow-Calf Production. J. Anim. Sci.
70:576-587.
Allen, V. G., J. P. Fontenot, and D. R. Notter. 1992b. Forage systems for Beef Production from Conception to Slaughter II. Stocker Systems. J. Anim. Sci. 70:588-596.
Allen, M. S. 1996. Physical constraints on voluntary intake of forages by ruminants. J. Anim.
Sci. 74:3063-3075.
Allen, M. S. 1997. Relationship between fermentation acid production in the rumen and the requirement for physically effective fiber. J. Dairy Sci. 80:1447-1462.
Allen, V. G., J. P. Fontenot, and R. A. Brock. 2000. Forage systems for production of stocker steers in the upper south. J. Anim. Sci. 2000. 78:1973-1982.
AOAC. 1990. Official Methods of Analysis. 15 ed. Association of Official Analytical Chemist, Arlington, VA.
Bagley, C. P., J. P. Fontenot, R. E. Blaser, and K. E. Webb, Jr. 1983. Nutritional value and voluntary intake of tall fescue (Festuca arundinacea Schreb.) fed to sheep. J. Anim.
Sci. 57:1383-1391.
Bargo, F., L. D. Muller, J. E. Delahoy, and T. W. Cassidy. 2002. Milk response to concentrate supplementation of high producing dairy cows grazing at two pasture allowances. J. Dairy Sci. 85:1777-1792.
Bargo, F., G. A. Varga, L. D. Muller, and E. S. Kolvert. 2003. Pasture intake and substitution effects on nutrient digestion and nitrogen metabolism during continuous culture fermentation. J. Dairy Sci. 86:1330-1340.
Barnhart, S., M. Duffy, and D. Smith. Estimated costs of pasture and hay production. Ag Decision Maker. File A1-15. www.extension.iastate.edu/agdm accessed May 2007
Baron, V. S., A. C. Dick, M. Bjorge, and G. Lastiwka. 2004. Stockpiling potential of
perennial forage species adapted to the canadian prairie parkland. Agron. J. 96:1545-1552.
Berge, P. 1991. Long-term effects of feeding during calfhood on subsequent performance in beef cattle (a review). Livestock Production Science. 28:179-201.
Bodine, T. N., H.T. Purvis II, and D. L. Lalman. 2001. Effects of supplement type on animal performance, forage intake, digestion, and ruminal measurements of growing beef cattle. J. Anim. Sci. 79:1041-1051.
Bodine, T. N. and H. T. Purvis II. 2003. Effects of supplemental energy and/or degradable intake protein on performance, grazing behavior, intake, digestibility, and fecal and blood indices by beef steers grazed on dormant native tallgrass prairie. J. Anim. Sci.
81:304-317.
Bohman, V. R. 1955. Compensatory growth of beef cattle: the effect of hay maturity. J.
Anim. Sci. 14:249-255.
Bohnert, D. W., C. S. Schauer, and T. DelCurto. 2002. Influence of rumen protein degradability and supplementation frequency on performance and nitrogen use in ruminants consuming low-quality forage: Cow performance and efficiency of nitrogen use in wethers. J. Anim. Sci. 80:1629-1637.
Bowman, J. G. P., B. F. Sowell, L. M. M. Surber, and T. K. Daniels. 2004. Nonstructural carbohydrate supplementation of yearling heifers and range beef cows. J. Anim. Sci.
82:2724-2733.
Brokaw, L., B. W. Hess, and D. C. Rule. 2001. Supplemental soybean oil or corn for beef heifers grazing summer pasture: Effects on forage intake, ruminal fermentation, and site and extent of digestion. J. Anim. Sci. 79:2704-2712.
Brokken, R. F. and A. C. Bywater. 1982. Application of isoquant analysis to forage:grain ratios in cattle feeding. J. Anim. Sci. 54:463-472.
Carey, D. A., J. S. Caton, and M. Biondini. 1993. Influence of energy source on forage intake, digestibility, in situ forage degradation, and ruminal fermentation in beef steers fed medium-quality brome hay. J. Anim. Sci. 71:2260-2269.
Carstens, G. E., D. E. Johnson, M. A. Ellenberger, and J. D. Tatum. 1991. Physical and chemical components of the empty body during compensatory growth in beef steers.
J. Anim. Sci. 69:3251-3264.
Cassar-Malek, I., S. Kahl, C. Jurie, and B. Picard. 2001. Influence of feeding level during postweaning growth hormone on circulating concentrations of thyroid hormones and estrathyroidal 5’-deiodination in steers. J. Anim. Sci. 79:2679-2687.
Caton, J. S. and D. V. Dhuyvetter. 1997. Influence of Energy Supplementation on Grazing Ruminants: Requirements and Responses. J. Anim. Sci. 75:533-542.
Choat, W. T., C. R. Krehbiel, G. C. Duff, R. E. Kirksey, L. M. Lauriault, J. D. Rivera, B. M.
Capitan, D. A. Walker, G. B. Donart, and C. L. Goad. 2003. Influence of grazing dormant native range or winter wheat pasture on subsequent finishing cattle
performance, carcass characteristics, and ruminal metabolism. J. Anim. Sci. 81:3191-3201.
CNCPS. 2000. Cornell Net Carbohydrate and Protein System. 5 ed. Cornell University, Ithica, NY.
Coleman, S. W., F. M. Pate, D. W. Beardsley. 1976. Effect of level of supplemental energy fed grazing steers on performance during the pasture and subsequent drylot period. J.
Anim. Sci. 42:27-35.
Coleman, S. W. and B. C. Evans. 1986. Effect of nutrition, age, and size on compensatory growth in two breeds of steers. J. Anim. Sci. 63:1968-1982.
Denham, A. H. 1977. Influence of energy and protein supplements on grazing and feedlot performance of steers. J. Anim. Sci. 45:1-7.
Desai, M. and C. N. Hales. 1997. Role of fetal and infant growth in programming metabolism in later life. Biol. Rev. 72:329-348.
Driskill, R., J. R. Russell, D. R. Strohbehn, D. G. Morrical, S. K. Barnhart, and J. D.
Lawrence. 2007. Effects of stocking rate and corn gluten feed supplementation on performance of young beef cows grazing winter-stockpiled tall fescue-red clover pasture. J. Anim. Sci. 85:1577-1586.
Drouillard, J. S., C. L. Ferrell, T. J. Klopfenstein, and R. A. Britton. 1991. Compensatory growth following metabolizable protein or energy restrictions in beef steers. J. Anim.
Sci. 69:811-818.
Drouillard, J. S. and G. L. Kuhl. 1999. Effects of previous grazing and management on feedlot performance of cattle. J. Anim. Sci. 77:136-146 suppl 2
Edwards, W. and D. Smith. 2007. Cash Rental Rates for Iowa 2007 Survey. Ag Decision Maker. File C2-10. FM 1851. Iowa State University Extension.
El-Kadi, S. W., K. R. McLeod, N. A. Elam, S. E. Kitts, C. C. Taylor, D. L. Harmon, B. J.
Bequette, and E. S. Vanzant. 2008. Nutrient net absorption across the portal-drained viscera of forage-fed beef steers: Quantitative assessment and application to a nutritional prediction model. J. Anim. Sci. 86:2277-2287.
Farmer, G. C., R. C. Cochran, D. D. Simms, E. A. Klevesahl, T. A. Wickersham, and D. E.
Johnson. 2001. The effects of several supplementation frequencies on forage use and the performance of beef cattle consuming dormant tallgrass prairie forage. J. Anim.
Sci. 79:2276-2285.
Faulkner, D. B., D. F. Hummel, D. D. Buskirk, L. L. Berger, D. F. Parrett, and G. F. Cmarik.
1994. Performance and nutrient metabolism by nursing calves supplemented with limited or unlimited corn or soybeans. J. Anim. Sci. 72:470-477.
Freetly, H.C. and J. A. Nienaber. 1998. Efficiency of energy and nitrogen loss and gain in mature cows. J. Anim. Sci. 76:896-905
Freetly, H. C., C. L. Ferrell, and T. G. Jenkins. 2000. Timing of realimentation of mature cows that were feed-restricted during pregnancy influences calf birth weights and growth rates. J. Anim. Sci. 78:2790-2796.
Gekara, O. J., E. C. Prigge, W. B. Bryan, M. Schettini, E. L. Nestor, and E. C. Townsend.
2001. Influence of pasture sward height and concentrate supplementation on intake, digestibility, and grazing time of lactating beef cows. J. Anim. Sci. 79:745-752.
Gelvin, A. A., G. P. Lardy, S. A. Soto-Navarro, D. G. Landblom, and J. S. Caton. 2004.
Effect of field pea-based creep feed on intake, digestibility, ruminal fermentation, and performance by nursing calves grazing native range in western North Dakota. J.
Anim. Sci. 82:3589-3599.
Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses (apparatus, reagents, procedures, and some applications). Agric. Handbook No. 379. ARS, USDA, Washington, D.C.
Goetsch, A. L., Z. B. Johnson, D. L. Galloway, Sr., L. A. Forster, Jr., A. C. Brake, W. Sun, K. M. Landis, M. L. Lagasse, K. L. Hall, and A. L. Jones. 1991. Relationship of body weight, forage composition, and corn supplementation to feed intake and digestion by Holstein steer calves consuming bermudagrass had ad libitum. J. Anim. Sci. 69:2634-2645.
Grainger, C. and G. L. Mathews. 1989. Positive relation between substitution rate and pasture allowance for cows receiving concentrates. Australian Journal of Experimental Biology. 29:355-360.
Grigsby, K. N., M. S. Kerley, J. A. Paterson, and J. C. Weigel. 1992. Site and extent of nutrient digestion by steers fed a low-quality bromegrass hay diet with incremental levels of soybean hull substitution. J. Anim. Sci. 70:1941-1949.
Hedtke, J. L., D. J. Undersander, M.D. Casler, and D.K. Combs. 2002. Quality of forage stockpiled in Wisconsin. J. Range. Manage. 55:33-42.
Heinemann, W. W. and R. W. Van Keuren. 1956. The effect of wintering plane of nutrition on subsequent gains of beef yearling steers on irrigated pastures. J. Anim. Sci.
15:1097-1102.
Heldt, J. S., R. J. Pruitt, C. P. Birkelo, P. S. Johnson, and Z. W. Wicks III. 1998. Evaluation of wheat middlings as a supplement for beef cows grazing native winter range with differing forage availabilities. J. Anim. Sci. 76:378-387.
Hermann M. L., J. R. Russell, and S. K. Barnhart. 2002. Evaluation of hay-type and grazing-tolerant alfalfa cultivars in season-long or complementary rotational stocking systems for beef cows. Journal of Animal Science. 80(3):768–779.
Hess, B. W., L. J. Krysl, M. B. Judkins, D. W. Holcombe, J. D. Hess, D. R. Hanks, and S. A.
Huber. 1998. Supplemental cracked corn or wheat bran for steers grazing endophyte-free fescue pastures: Effects on live weight gain, nutrient quality, forage intake, particulate and fluid kinetics, ruminal fermentation, and digestion. J. Anim. Sci.
74:1116-1125.
Hitz, A.C., and J.R. Russell. 1998. Potential of stockpiled perennial forages in winter grazing systems for pregneant beef cows. J. Anim. Sci. 76:404-415.
Horn, G. W., M. D. Cravey, R. T. McCollum, C. A. Strasia, E. G. Krenzer, Jr., and P.L.
Claypool. 1995. Influence of high-starch vs high-fiber energy supplements on performance of stocker cattle grazing wheat pasture and subsequent feedlot performance. 73:45-54.
Horn, G. W., P. A. Beck, J. G. Andrae, and S. I. Paisley. 2005. Designing supplements for stocker cattl grazing wheat pasture. J. Anim. Sci. 83(E. Suppl.):E69-E78.
Horton, G. M. J. and W. Holmes. 1978. Compensatory Growth by Beef Cattle at Grassland or on an Alfalfa-Based Diet. J. Anim. Sci. 46:297-303.
Iowa State University Extension; Ag Decision Maker: Livestock Budgets for Iowa. FM 1815.
File B1-21. Revised March 2008.
Janovick, N.A., Russell, J.R., Strohbehn,D.R., and Morrical, D.G. 2004. Productivity and hay requirements of beef cattle in a Midwestern year-round grazing system. J. Anim. Sci.
82:2503-2515
Johnson, K. A. and D. E. Johnson. 1995. Methane emissions from cattle. J. Anim. Sci.
73:2483-2492.
Jordan, D. J., T. J. Klopfenstein, and D. C. Adams. 2002. Dried poultry waste for cows grazing low-quality winter forage. J. Anim. Sci. 80:818-824.
Jung, G. H. and M. S. Allen. 1995. Characteristics of plant cell walls affecting intake and digestibility of forages by ruminants. J. Anim. Sci. 73:2774-2790.
Kallenbach, R. L., G. J. Bishop-Hurley, M. D. Massie, G. E. Rottinghaus, and C. P. West.
2003. Herbage mass, nutritive value, and ergovaline concentration of stockpiled tall fescue. Crop Sci. 43:1001-1005.
Karn, James F. 2000. Supplementation of yearling steers grazing Northern Great Plains rangelands. J. Range Manage. 53:170-175.
Kartchner R. J. 1981. Effects of protein and energy supplementation of cows grazing native winter range forage on intake and digestibility. J. Anim. Sci. 51:432-438.
Kleinschmit, D. H., J. L. Anderson, D. J. Schingoethe, K. F. Kalscheur, and A. R. Hippen.
2007. Ruminal and intestinal degradability of distillers grains plus soluble varies by source. J. Dairy Sci. 90:2909-2918.
Klopfenstein, T. J., G. E. Erickson, and V. R. Bremer. 2008. Use of distillers by-products in the beef cattle feeding industry. J. Anim. Sci. 86:1223-1231.
Knoblich, H. V., F. L. Fluharty, and S. C. Loerch. 1997. Effects of programmed gain
strategies on performance and carcass characteristics of steers. J. Anim. Sci. 75:3094-3102.
Köster, H. H., R. C. Cochran, E. C. Titgemeyer, E. S. Vanzant, Il Abdelgadir, and G. St-Jean.
1996, Effect of increasing degradable intake protein on intake and digestion of low-quality, tallgrass-prairie forage by beef cows. J. Anim. Sci. 74:2473-2481.
Lake, R. P., R. L. Hildebrand, D. C. Clanton, and L. E. Jones. 1974. Limited energy supplementation of yearling steers grazing irrigated pasture and subsequent feedlot performance. J. Anim. Sci. 39:827-833.
Lalman, D. L., C. M. Taliaferro, F. M. Epplin, C. R. Johnson, and J. S. Wheeler. 2000.
Review: Grazing stockpiled bermudagrass as an alternative to feeding harvested forage. Proceedings of the American Society of Animal Science.
Lawrence: Steers 500-600# prices, monthly average, and seasonality index
http://www.econ.iastate.edu/outreach/agriculture/periodicals/chartbook/Chartbook2/T ables/Table18b.pdf Accessed May 15, 2008.
Lawrence: Steers 700-800# prices, monthly average, and seasonality
indexhttp://www.econ.iastate.edu/outreach/agriculture/periodicals/chartbook/Chartbo ok2/Tables/Table18c.pdf Accessed May 15, 2008.
Lawrence: Choice Steer prices, monthly average, and seasonality
indexhttp://www.econ.iastate.edu/outreach/agriculture/periodicals/chartbook/Chartbo ok2/Tables/Table18d.pdf Accessed May 15, 2008.
Lawrence: Cull Cow prices, monthly average, and seasonality
indexhttp://www.econ.iastate.edu/outreach/agriculture/periodicals/chartbook/Chartbo ok2/Tables/table18e.pdf Accessed May 15, 2008.
Lawrence: Summary of Estimated Returns
http://www.econ.iastate.edu/faculty/lawrence/Lawrence_Website/estreturns.htm Accessed May 15, 2009.
Lawrence: Optimal marketing weight for fed cattle. Iowa Beef Center at Iowa State University http://www.iowabeefcenter.org/content/feedlot/optimalweight.pdf Accessed May 15, 2009.
Lewis, J. M., T. J. Klopfenstein, R. A. Stock, and M. K. Nielson. 1990. Evaluation of intensive vs extensive systems of beef production and the effect of level of beef cow milk production on postweaning performance. J. Anim. Sci. 68:2517-2524.
Llewellyn, D. A., R. C. Cochran, T. T. Marston, D. M. Grieger, C. G. Farmer, T. A.
Wickerham. 2006. Influence of limited fall protein supplementation on performance and forage utilization by beef cattle grazing low quality native grass pastures. Animal Feed Science and Technology. 127:234-250.
Lodge, S. L., R. A. Stock, T.J. Klopfenstein, D. H. Shain, and D. W. Herold. 1997.
Evaluation of corn and sorghum distillers byproducts. J. Anim. Sci. 75:37-43.
Lofgreen, G. P. and H. E. Kiesling. 1985. Effects of receiving and growing diets on compensatory gains of stressed calves. J. Anim. Sci. 61:320-328.
Loy, T. W., J. C. Macdonald, T. J. Klopfenstein, and G. E. Erickson. 2007. Effects of dried distillers grains or corn supplemantation on forage intake and digestibility. J. Anim.
Sci. 85:2625-2630.
Macdonald, J. C., T. J. Klopfenstein, G. E. Erickson, and W. A. Griffin. 2007. Effects of dried distillers grains and equivalent undegradable intake protein or ether extract on performance and forage intake of heifers grazing smooth bromegrass pastures. J.
Anim. Sci. 85:2614-2624.
Machado, C. F., S. T. Morris, J. Hodgson, H. Berger and N. J. Auza. 2006. Effect of maize grain and herbage allowance on estimated metabolizable energy intake and animal performance in beef cattle finishing systems. Grass and Forage Science. 61:385-397.
Marten, G.C. and R. F. Barnes. 1979. Prediction of energy digestibility of forages with in vitro rumen fermentation and fungal enzyme systems. Pages 61-71 in Proc. Int.
Workshop Standardization of Analytical Methodology for Feeds. Int. Dev. Res.
Center and Int. Union Nutr. Sci., Ottawa, Canada.
Matejovsky, K. M. and D. W. Sanson. 1995. Intake and digestion of low-, medium-, and high-quality grass hays by lambs increasing levels of corn supplementation. J. Anim.
Sci. 73:2156-2163.
May, G. J., L. W. Van Tassell, J. W. Waggoner, and M. A. Smith. 1999. Relative costs and feeding strategies associated with winter/ spring calving. J. Range Manage. 52:560-568.
May, G. J., J. R. Russell, N. A. Janovick, J. D. Lawrence, D. R. Strohbehn, and D. G.
Morrical. An economic comparison of year round vs conventional grazing systems in Iowa. http://www.iowabeefcenter.org/pdfs/econ_yrrndgr.pdf Accessed June 26, 2008
McCarthy, S., B. Horan, M. Rath, M. Linnane, P. O’Connor, and P. Dillon. 2007. The influence of strain of Holstein-Friesian dairy cow and pasture-based feeding system
McCarthy, S., B. Horan, M. Rath, M. Linnane, P. O’Connor, and P. Dillon. 2007. The influence of strain of Holstein-Friesian dairy cow and pasture-based feeding system