Progress 10/01/01 to 09/30/06
Outputs
Two experiments were conducted to develop alternative management practices to reduce stress and improve animal health, well-being, and performance. In experiment 1, 375 steers were utilized to determine the effects of growth implants and trace mineral (TM) supplementation and source on immune response. Steers were stratified by initial body weight and were randomly assigned pens. Treatments consisted of: 1) control (no supplemental Cu, Zn, Mn, and Co), 2) inorganic (INORG) TM (CuSO4, ZnSO4, MnSO4, and CoCO3), and 3) organic (ORG) TM (iso-amounts of ORG Cu, Zn, Mn, and Co). On d 28 post arrival to the feedlot, steers from 6 pens per treatment received a growth implant, while the other half of the steers within the same treatment (6 pens) did not receive a growth implant. At the beginning of the finishing phase, only steers receiving growth implants during the growing phase were re-implanted. During the finishing phase, all minerals excluding Zn, were fed at NRC
recommended concentrations in INORG form. Treatments during the finishing phase consisted of: 1) control (no supplemental Zn), 2) INORG Zn (30 ppm Zn from ZnSO4), and 3) ORG Zn (iso-amounts of ORG Zn). At the end of the growing phase, steers receiving ORG TM had greater total IgM concentrations than INORG-supplemented steers and implanted steers tended to have higher IgG antibody titer concentrations specific for pig red blood cells than non-implanted steers. In experiment 2, 375 steers were utilized to determine the effects of trace mineral (TM) supplementation and source on performance during the on-farm backgrounding and feedlot receiving phases of beef cattle production. At their respective ranches, steers were stratified by body weight into six groups. Groups were then assigned to one of six pens and pens were randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental trace minerals), 2) inorganic trace mineral (CuSO4, ZnSO4, MnSO4, and CoCO3), and 3)
organic trace mineral (iso-amounts of organic Cu, Zn, Mn, and Co). Mineral treatments were fed in alfalfa pellets. Steers were allowed free access to harvested alfalfa-grass hay throughout the 30-d on-farm backgrounding phase. On day 30 post-weaning, steers were weighed and transported to the feedlot. Steers were blocked by treatment within ranch, stratified by initial body weight, and randomly assigned to one of 36 pens (9-12 head per pen; 12 pens per treatment). Steers remained on the same on-farm backgrounding trace mineral treatments, however, trace mineral treatments were included in the total mixed growing ration. Steers were fed a corn silage-based growing diet throughout the 28 d feedlot receiving period. There was no effect of TM supplementation on performance of steers during the on-farm backgrounding phase. By the end of the 28-d feedlot receiving phase, ADG was similar between control and trace mineral supplemented steers. Steers supplemented with organic TM had greater
ADG than steers supplemented with inorganic TM by the end of the 28-d feedlot receiving phase. Morbidity and mortality rates were similar across treatments.
Impacts
Although trace mineral supplementation is an important nutritional component for beef cattle, other factors such as overall animal management, environment, reduced feed intake during receiving, breed type, antagonistic compounds to trace mineral absorption/metabolism present in the diet and water, and disease status may impact an animals overall performance
Publications
- Baszczak, J. A., T. Grandin, S. L. Gruber, T. E. Engle, W. J. Platter, S. B. Laudert, A. L. Schroeder, and J. D. Tatum JD. 2006. Effects of ractopamine supplementation on behavior of British, Continental, and Brahman crossbred steers during routine handling. J. Anim. Sci. 84:3410-3414.
- Murrieta, C. M., B. W. Hess, E. J. Scholljegerdes, T. E. Engle, K. L. Hossner, G. E. Moss, and D. C. Rule. 2006. Evaluation of milk somatic cells as a source of mRNA for study of lipogenesis in the mammary gland of lactating beef cows supplemented with dietary high-linoleate safflower seeds. J. Anim. Sci. 84:2399-2405.
- Legleiter, L. R., J. K. Ahola, T. E. Engle, J. W. Spears. 2006. Decreased brain copper due to copper deficiency has no effect on bovine prion proteins. Biochem. Biophy. Res. Comm. 352:884-888.
- Dorton, K. L., T. E. Engle, and R. M. Enns. 2006. Effects of trace mineral supplementation and source, 30 days post-weaning and 28 days post receiving, on performance and health of feeder cattle. Asian-Aust. Anim. Sci. 19:1450-1454.
- Richardson, S. M., P. D. Siciliano, T. E. Engle, C. K. Larson, and T. L. Ward. 2006. Effect of selenium supplementation and source on the selenium status of horses. J. Anim. Sci. 84:1742-1748.
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Progress 01/01/05 to 12/31/05
Outputs
Feeder cattle are exposed to various degrees of stress during transportation. Stress associated with shipping may result in lower dry matter intakes and increased susceptibility to respiratory tract and other infectious diseases. This may, in turn, increase morbidity and mortality rates of newly received calves arriving to a feedlot which can impact overall feedlot profitability (Hutcheson and Cole, 1986; Hutcheson, 1989). Zinc (Zn) and copper (Cu), and to some extent manganese (Mn), and cobalt (Co), have been shown to play a role in the immune response of cattle (Underwood, 1971; McDowell, 1992;Galyean et al., 1999; Spears, 2000). Therefore, supplementing the appropriate trace minerals in proper amounts prior to transport of newly weaned calves may allow for increased stores of essential trace minerals that may possibly be utilized during times of stress and reduced feed intake normally observed in newly received calves (Hutcheson and Cole, 1986). Some attention has
been focused on the role of trace mineral nutrition in the immunological adaptation of beef cattle to stress. However, little focus has been placed on mineral supplementation to weaned calves prior to transport to the feedlot. Therefore, the objective of this experiment was to determine the effects of trace mineral supplementation and source for 30 days post weaning on performance and health of newly received feedlot cattle. Three hundred and seventy-five steers were utilized to determine the effects of trace mineral (TM) supplementation and source on performance during the on-farm backgrounding and feedlot receiving phases of beef cattle production. At their respective ranches, calves were stratified by body weight into six groups. Groups were then assigned to one of six pens. Pens were then randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental trace minerals), 2) inorganic trace mineral (Cu, Zn, Mn, and Co), and 3) organic trace mineral (iso-amounts
of organic Cu, Zn, Mn, and Co). Mineral treatments were fed in alfalfa pellets. Control steers received alfalfa pellets with no additional Cu, Zn, Mn, or Co. Calves were allowed free access to harvested alfalfa-grass hay throughout the 30 d on-farm backgrounding phase. On d 30 post-weaning, calves were weighed and transported to the feedlot. Steers were blocked by treatment within ranch, stratified by initial body weight, and randomly assigned to one of 36 pens (9 to 12 head per pen; 12 pens per treatment). Steers remained on the same on-farm backgrounding trace mineral treatments, however, trace mineral treatments were included in the total mixed growing ration. Steers were fed a corn silage-based growing diet throughout the 28 d feedlot receiving period. There was no effect of TM supplementation on performance of steers during the on-farm backgrounding phase. By the end of the 28 d feedlot receiving phase, ADG was similar between control and trace mineral supplemented steers.
However steers that were supplemented with organic TM had greater ADG than steers supplemented with inorganic TM by the end of the 28 d feedlot receiving phase. Morbidity and mortality rates were similar across treatments.
Impacts
Feeder cattle are exposed to various degrees of stress during transportation. Stress induced by transportation can have negative impacts on cattle performance and overall profitability. Other factors such as overall animal management, environment, reduced feed intake during receiving, breed type, antagonistic compounds to trace mineral absorption/metabolism present in the feed and water, and disease status may impact an animals overall performance. Therefore, further research is needed to determine the effects of TM supplementation post weaning and prior to transport to the feedlot on performance and health of beef cattle.
Publications
- Ahola, J. K., Baker, D.S., Burns,P.D., Whittier, J.C., and Engle, T.E. 2005. Effect of copper, zinc, and manganese source on mineral status, reproduction, immunity, and calf performance in young beef females over a two-year period. Prof. Anim. Sci. 21:397-304.
- Ahola, J. K., Sharpe, L.R., Dorton, K.L., Burns, P.D., Stanton, T.L., and Engle, T.E. 2005. Effects of lifetime copper, zinc, and manganese supplementation and source on performance, mineral status, immunity, and carcass characteristics of feedlot cattle. Prof. Anim. Sci. 21:305-317.
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Progress 01/01/04 to 12/31/04
Outputs
Stress induced by transportation can have a negative impact on the ability of a calf to absorb and metabolize trace minerals. This depletion in trace mineral status due to transportation stress can cause increased susceptibility of a calf to respiratory tract and other infectious diseases upon arrival to a feedlot (Hutcheson and Cole, 1986). Several experiments have focused on trace mineral supplementation during the cow/calf or feedlot phases. However, the effects of lifetime (pre-natal through harvest) trace mineral supplementation and source on feedlot performance and health have not been well addressed. Therefore, the objectives of this experiment were to evaluate the effects of lifetime supplementation and source (organic vs. inorganic) of Cu, Zn, and Mn on feedlot performance, mineral status, immunity, and carcass traits in beef cattle during the feedlot growing and finishing phases. Two consecutive calf crops consisting of 170 steers (n equal to 90, Year 1; n
equal to 80, Year 2) and 100 heifers (n equal to 50, Year 1; n equal to 50, Year 2) from the same cowherd were utilized in this experiment. Calves dams were supplemented with one of three free-choice trace mineral treatments from approximately 80 d pre-calving through 120 d post-calving. Treatments consisted of: 1) Control (no supplemental Cu, Zn, or Mn); 2) Organic (ORG; 50 percent organic and 50% inorganic Cu, Zn, and Mn); or 3) Inorganic (ING; 100 percent inorganic Cu, Zn, and Mn) trace minerals. The ORG and ING free-choice trace mineral treatments were formulated to supply 10 ppm Cu, 30 ppm Zn, and 40 ppm Mn. Calves were also given exclusive access to the same trace mineral treatments as their dams via creep feeders from approximately 95 d of age until weaning. Upon arrival to the feedlot, calves were maintained on the same pre-weaning trace mineral treatments, except that the ORG treatment was reformulated to contain 33 percent organic and 67 percent inorganic Cu, Zn, and Mn, and
both ORG and ING treatments were formulated to supply 10 ppm Cu, 30 ppm Zn, and 20 ppm Mn. Cattle were fed a growing ration for 56 d and a high concentrate finishing diet for 140 d (Year 1) and 145 or 181 d (Year 2) prior to harvest. Initial and final BW, ADG, and DMI were similar across treatments for both years. There was a tendency for a yr (times) treatment interaction (P less than 0.10) for gain to feed ratio (G:F). In Year 1, ORG-supplemented cattle had a greater (P less than 0.05) G:F than ING-supplemented cattle throughout the entire feeding period while non-supplemented control cattle had a greater (P less than 0.01) G:F than supplemented cattle during the finishing phase. In Year 2, G:F were similar across treatments. Supplemented cattle had greater (P less than 0.01) liver Cu concentrations than non-supplemented controls throughout the entire feeding period, and liver Mn concentrations were greater (P less than 0.02) in supplemented cattle than non-supplemented controls at
the end of the finishing phase. Immune response, morbidity, and carcass traits were not affected by either trace mineral supplementation or source.
Impacts
The combined effects of lifetime (prenatal through harvest) copper, zinc, and manganese supplementation and source on feedlot performance, mineral status, health, immune response, and carcass traits have not been well addressed in the literature. Experiments that have evaluated individual trace minerals such as copper or zinc indicate that both supplementation and source can impact mineral status, performance, health, and carcass characteristics during the feeding phase. However, when trace minerals were supplemented to cattle from the late fetal stage through harvest in the current experiment, liver copper and manganese concentrations and the gain-to-feed ratio were affected. Increasing the trace mineral status of a calf prior to transportation to a feedlot may be beneficial if the calf is exposed to environmental and biological stressors upon arrival.
Publications
- Ahola, J. K. D. S. Baker, P. D. Burns, R. G. Mortimer, R. M. Enns, J. C. Whittier, T. W. Geary, and T. E. Engle. 2004. Effect of copper, zinc, and manganese supplementation and source on reproduction, mineral status, and performance in grazing beef cattle over a two-year period. J. Anim. Sci. 82:2375-2383.
- Engle, T. E. and J. W. Spears. 2004. Effects of finishing system (feedlot or pasture), high oil maize, and copper on conjugated linoleic acid and other fatty acids in muscle of finishing steers. Anim. Sci.78:261-269.
- Creech, B. L., J. W. Spears, W. L. Flowers, G. M. Hill, K. E. Lloyd, T. A. Armstrong, and T. E. Engle. 2004. Effects of trace mineral concentration and source (inorganic vs. chelated) on performance, mineral status, and fecal mineral excretion in pigs for weaning through finishing. J. Anim. Sci. 82:2140-2147.
- Bryant, T. C., J. J. Wagner, T. E. Engle, K. L. Dorton, P. D. Burns, and M. L. Galyean. 2004. Effects of feeding supplemental vitamin A concentration on growth, intake, and marbling of yearling feedlot steers. J. Anim. Sci (Suppl. 1):270.
- Whitman, K. J., T. E. Engle, P. D. Burns, K. L. Dorton, J. K. Ahola, K. J. LaVelle, N. E. Wamsley, C. R. Johnson, and T. L. Stanton. 2004. Effects of copper and zinc source on performance and carcass characteristics in finishing steers. 2004. Animal Sciences Research Report. Pp. 1-4.
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Progress 01/01/03 to 12/31/03
Outputs
Feeder cattle that have been shipped are subjected to various degrees of stress. Morbidity and often mortality rates are high in these animals. Costs associated with morbidity are important in determining profitability of feedlot cattle. Several researchers monitoring ranch-to-rail programs have reported net return differences among cattle that have remained healthy throughout the feeding period vs. morbid cattle. However, the majority of reports have only monitored morbidity and mortality during the feeding period. Limited information is available relative to immune response and feed efficiency. Furthermore, Cu and Zn have been shown to play an important role in the immune response of cattle. Therefore, supplementing these trace minerals to calves upon arrival to the feedlot may allow for an enhanced immune response when calves are exposed to stressors such as transport and the new feedlot environment. Therefore, the objective of this experiment was to determine the
effects of trace mineral source on feedlot performance, immune status, carcass characteristics, and lung scores. Three hundred and sixty steer calves from three different Colorado State University Agriculture Research Experiment Stations weighing approximately 230 kg were utilized in this experiment. Upon arrival to the feedlot steers were stratified by origin and body weight and randomly assigned to one of thirty-six ten head pens. Pens were then randomly assigned to treatments. Treatment consisted of: 1) inorganic trace minerals (Cu, Zn, Mn, and Co in sulfate form), and 2) organic minerals. Steers were fed a corn silage- based growing diet for 56 d then gradually switched to a high concentrate finishing diet until they reach a finished weight of approximately 580 kg. During the finishing phase, all minerals, excluding Zn, were fed at the recommended concentrations in inorganic form. Treatments during the finishing phase consisted of: 1) inorganic Zn (60 mg of Zn/kg DM from Zn
sulfate) and 2) iso-amounts of organic Zn. On day 190 and 220 equal numbers of animals from each treatment were transported to a slaughter plant where carcass data and lung lesion scores were collected. During the growing and finishing phase, ADG, ADFI, and feed efficiency were similar across treatments. Liver Cu concentrations were higher on d 56 (p less than 0.05) and d 168 (p less than 0.04) in steers consuming organic trace minerals relative to steers consuming inorganic trace minerals. Immunoglobulin-G, IgM, INF gamma, SOD activity, antibody titer concentration specific for ovalbumin antigen, and morbidity and mortality were similar across treatments. Percent KPH, PYG, fat thickness, REA final yield grade, dressing percentage, marbling, and lung score did not differ among treatments.
Impacts
These data indicate that trace mineral source may have an impact on liver Cu status. Increasing liver Cu status may allow for a potential Cu reserve for immune cells during an immune challenge that an animal may encounter during the feeding period.
Publications
- Wamsley, N.E., Burns, P.D., Engle, T.E., and Enns. R.M. 2003. Effect of fishmeal supplementation on endometrial sensitivity to oxytosin in beef heifers having low leuteal phase progesterone. Western Section American Society of Animal Science Proceedings. 54:302-305.
- Engle, T. E. 2003. Trace mineral metabolism in ruminants: Impacts on production and the environment. Colorado Dairy Nutrition Conference Proceedings.
- Ahola, J.K., Engle, T.E., Baker, D.S., Sharpe, L.R., Burns, P.D., Enns, R.M., and Mortimer.R.G. 2003. Impact of trace mineral supplementation and source on grazing beef cattle over a two-year period. Animal Sciences Research Report. Pp. 1-4.
- Dorton, K.L., Engle, T.E., Kimberling, C.V., Parsons, G., Ames, D.R., and Enns, R.M. 2003. Effects of copper source and growth implants on performance, immunity, and carcass characteristics of growing and finishing steers. Animal Sciences Research Report. Pp. 37-40.
- Sharpe, L. R., Engle, T.E., Baker, D.S., Dorton, K.L., Ahola, J.K., Ames, D.R., Kimberling, C.V., and Parsons, G. 2003. Effects of trace mineral source on performance, health, and carcass characteristics of feedlot cattle. Animal Sciences Research Report. Pp. 41-44.
- Dorton, K.L., Engle, T.E., Kimberling, C.V., Parsons, G., Ames, D.R., and Enns, R.M. 2003. Effects of trace mineral source and growth implants on performance and lipid metabolism of steers. J. Anim. Sci. 81(Suppl. 1): 215. Western Section American Society of Animal Science Proceedings. 54:354-357.
- Ahola, J.K., Engle, T.E., Baker, D.S., Sharpe, L.R., Whittier, J.C., Burns, P.D., Enns, R.M., and Mortimer, R.G. 2003. Impact of trace mineral supplementation and source on grazing beef cattle over a two-year period. J. Anim. Sci. 81(Suppl. 1): 36.
- Siciliano, P. D., Webel, S.K., Brown, L.S., Warren, L.K., Engle, T.E., and Burns, P.D. 2003. Effects of n-3 polyunsaturated fatty acid source on plasma fatty acid profiles of horses. J. Anim. Sci. 81(Suppl. 1): 72.
- Wamsley, N.E., Burns, P.D., Engle, T.E., and Enns, R.M. 2003. Effect of fishmeal supplementation on endometrial sensitivity to oxytosin in beef heifers having low leuteal phase progesterone. J. Anim. Sci. 81(Suppl. 1): 102.
- Ahola, J.K., Engle, T.E., Baker, D.S., Sharpe, L.R., Whittier, J.C., Burns, P.D., Enns, R.M., and Mortimer, R.G. 2003. Impact of trace mineral supplementation and source on grazing beef cattle over a two-year period. Western Section American Society of Animal Science Proceedings. 54:9-12.
- Dorton, K.L., Engle, T.E., Kimberling, C.V., Parsons, G., Ames, D.R., and Enns, R.M. 2003. Effects of trace mineral source and growth implants on performance, immunity, and carcass characteristics of growing and finishing steers. Western Section American Society of Animal Science Proceedings. 54:354-357.
- Roeber, D.L., Belk, K.E., Engle, T.E., Field, T.G., Koontz, S.R., Scanga, J.A., Tatum, J.D., Mason, G.L., Van Metre, D., Garry, F.B., and Smith. G.C. 2003. The effect of vitamin E supplementation on discoloration of injection-site lesions in retail cuts and the greening reaction observed in injection-site lesions of muscles of the chuck. J. Anim. Sci. 81:1885-1894.
- Dorton, K. L., T. E. Engle, D. W. Hamar, P. D. Siciliano, and R. S. Yemm. 2003. Effects of copper source and concentration on copper status and immune function in growing and finishing steers. Animal Feed Sci. and Tech. 110:31-44.
- Spears, J. W., PAS, Engle, T.E., PAS, Platter, W.R., Lloyd, K.E., Belk, K.E., and Horton, J. PAS. 2003. Effect of high dietary calcium propionate and dietary cation-anion balance on calcium metabolism and longissimus muscle tenderness in finishing steers. Prof. Anim. Sci. 19:239-243.
- Burns, P.D., Engle, T.E., Harris, M.A., Enns, R.M., and Whittier, J.C. 2003. Effect of fish meal supplementation on plasma and endometrial fatty acid composition in nonlactating beef cows. J. Anim. Sci. 81:2840-2846.
- Rhoads, A.R., Stanton, T.L.,PAS, Engle, T.E., PAS, and Kimberling, C.V. 2003. Effects of concentration and source of trace minerals on performance, immunity, mineral and lipid metabolism, and carcass characteristics of beef steers. Prof. Anim. Sci. 19:150-158.
- Johnson, L.R. and Engle, T.E. 2003. The effects of copper source and concentration on lipid metabolism in growing and finishing Angus steers. Asian-Aust. J. Anim. Sci. 16:1131-1136.
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Progress 01/01/02 to 12/31/02
Outputs
Feeder cattle that have been shipped are subjected to various degrees of stress. Stress associated with shipping results in increased susceptibility to respiratory tract and other infectious diseases. Morbidity and often mortality rates are high in these animals, despite vaccination against respiratory diseases. Feed intake can also be greatly reduced in cattle that have been stressed by shipping. Typically trace minerals are fed in excess to compensate for the decrease in feed intake observed in weaned calves arriving to the feedlot. Thus, resulting in excess mineral excretion by the animal. In order to minimize excretory losses of metals, sources providing better utilization to the animal must be found. In order to do this, criteria of mineral adequacy and availability must be established using immunological, hormonal, and biochemical indices. Therefore the objective of this experiment was to determine the effects of trace mineral source on performance, health
status, and carcass characteristics of feedlot steers. Three hundred and twenty three stressed steer calves were utilized in this experiment. Steers were blocked by ranch and stratified by initial body weight and randomly assigned to one of 36 ten head pens. Pens within a block were then randomly assigned to treatments. Treatment consisted of: 1) control (no supplemental Cu, Zn, Mn, and Co), 2) inorganic mineral (Cu, Zn, Mn, and Co in sulfate form), and 3) organic mineral. At the beginning of the experiment, half of the animals/treatment (6 pens) received a Synovex-S implant and the other animals received no implant. Steers were fed a corn silage- based growing diet for 56 d then gradually switched to a high concentrate finishing diet. During the finishing phase, all minerals, excluding Zn, were fed at the recommended concentrations in inorganic form. Treatments during the finishing phase consisted of: 1) control (no supplemental Zn), 2) inorganic Zn (30 mg of Zn/kg DM from Zn
sulfate), and 3) iso-amounts of organic Zn. Equal numbers of steers per treatment were slaughtered after receiving the finishing diet for 132 or 158 d. During the growing phase, implant and Zn supplementation had no effect on body weights, ADG, ADFI, and FE. During the finishing phase, implanted steers had greater final body weights and ADG (P less than 0.02) than steers that were not implanted. Steers supplemented with zinc sulfate had greater (P less than 0.02) back fat thickness than steers supplemented with organic Zn. Overall, implanted steers had lower (P less than 0.01) marbling scores than non-implanted steers and steers that were supplemented with Zn had greater (P less than 0.05) dressing percentage than control steers. Antibody titers specific for foreign protein and interferon gamma were similar across treatments. Morbidity (P less than 0.01) and mortality (P less than 0.01) were higher in implanted steers.
Impacts
These results indicate that Zn source and implant strategy may have an effect on performance, carcass characteristics, and morbidity and mortality.
Publications
- Lee, S. H., T. E. Engle, and K. L. Hossner. 2002. Effects dietary copper on the expression of lipogenic genes and metabolic hormones in steers. J. Anim. Sci. 80:1999-2005.
- Vierboom, M. M., T. E. Engle, P. D. Siciliano, and C. V. Kimberling. 2002. Effects of gestational status on apparent absorption and retention of copper and zinc in cows and ewes. Western Section American Society of Animal Science Proceedings. 53:519-522.
- Dorton, K. L., T. E. Engle, D. W. Hamar, P. D. Siciliano, and R. S. Yemm. 2002. Effects of source and concentration on performance, copper status, and immune function in growing and finishing feedlot steers. Western Section American Society of Animal Science Proceedings. 53:515-518.
- Wooley, M. K., T. E. Engle, and J. W. Spears. 2002. Effects of finishing system (confinement vs. pasture), supplemental fat, and copper on performance, carcass characteristics, and lipid metabolism in finishing steers. Western Section American Society of Animal Science Proceedings. 53:507-510.
- Rhoads, A. R., T. L. Stanton, T. E. Engle, and C. V. Kimberling. 2002. Effects of concentration and source of trace minerals on performance, immunity, mineral and lipid metabolism and carcass characteristics of beef steers. Western Section American Society of Animal Science Proceedings. 53:502-506.
- Flatt, W. R., T. L. Stanton, D. Schutz, J. Davis, and T. E. Engle. 2002. Effect of salt level on growth performance, carcass characteristics, cost of gain and manure salinity on finishing beef steers. Western Section American Society of Animal Science Proceedings. 53:660-665.
- T. E. Engle and D. S. Baker. 2002. Effect of mineral nutrition on immune function and factors that affect trace mineral requirements of beef cattle. In: 23rd Western Nutrition Conference, Pre-Conference Symposium. Pp 1-12.
- Engle, T. E. Trace Mineral Nutrition and Immunity in beef cattle. 2002. Prince Agri Products, Inc. Twenty-second Annual Feed Ingredient Conference. Pp. 90-97.
- M. M. Vierboom, T. E. Engle, P. D. Siciliano, C. V. Kimberling. 2002. Effects of gestational status on apparent absorption and retention of copper and zinc in primiparous cows. Department of Animal Sciences, Colorado State University. Animal Sciences Research Report. Pp. 17-19.
- L. R. Johnson and T. E. Engle. 2002. The effect of copper source and concentration on lipid metabolism, carcass characteristics, and fatty acid profile in growing and finishing Angus steers. Department of Animal Sciences, Colorado State University. Animal Sciences Research Report. Pp. 113-116.
- K. L. Dorton, T. E. Engle, D. W. Hamar, P. D. Siciliano, and R. S. Yemm. 2002. Effects of copper source and concentration on performance, copper status, and immune function in growing and finishing steers. Department of Animal Sciences, Colorado State University. Animal Sciences Research Report. Pp. 117-122.
- D. B. Abbey, D. R. Ames, and T. E. Engle. 2002. Effects of magnesium source on performance and carcass characteristics of steers. Department of Animal Sciences, Colorado State University. Animal Sciences Research Report. Pp. 127-129.
- D. B. Abbey, D. R. Ames, and T. E. Engle. 2002. Effect of magnesium (Mg) source on digestibility and buffering capacity in cattle. Department of Animal Sciences, Colorado State University. Animal Sciences Research Report. Pp. 109-112.
- A. R. Rhoads, T. L. Stanton, T. E. Engle, and C. V. Kimberling. 2002. Effects of source and concentration of trace minerals on feedlot performance, immunity, mineral status, carcass characteristics, and fatty acid profile of the Longissimus muscle of beef steers. Department of Animal Sciences, Colorado State University. Animal Sciences Research Report. Pp. 131-136.
- Loza, P. L., T. L. Stanton, T. E. Engle, D. Schutz, and A. R. Rhoads. 2002. Effects of feeding low phytate corn varieties on growth performance, feed efficiency, serum phosphorus level, Longissimus Dorsi fatty acid composition, and carcass characteristics of finishing steers. 2002. Department of Animal Sciences, Colorado State University. Animal Sciences Research Report. Pp. 123-126.
- J. W. Spears, and T. E. Engle. 2002. Finishing cattle on pasture with limited grain increases conjugated linoleic acid 9CLA) in beef. Animal Science Report. North Carolina State University.
- Vierboom, M. M., T. E. Engle, P. D. Siciliano, and C. V. Kimberling. 2002. Effects of gestational status on apparent absorption and retention of copper and zinc in cows and ewes. J. Anim. Sci. 80(Suppl. 2): 136-137.
- Dorton, K. L., T. E. Engle, D. W. Hamar, P. D. Siciliano, and R. S. Yemm. 2002. Effects of source and concentration on performance, copper status, and immune function in growing and finishing feedlot steers. J. Anim. Sci. 80(Suppl. 2): 136.
- Wooley, M. K., T. E. Engle, and J. W. Spears. 2002. Effects of finishing system (confinement vs. pasture), supplemental fat, and copper on performance, carcass characteristics, and lipid metabolism in finishing steers. J. Anim. Sci. 80(Suppl. 2): 136.
- Johnson, L. R., T. E. Engle, and C. K. Swenson. 2002. The effects of copper source and concentration on lipid metabolism in growing and finishing steers. J. Anim. Sci. 80(Suppl. 2): 116.
- Baker, D. S., T. E. Engle, J. C. Whittier, P. D. Burns, R. G. Mortimer, D. N. Schutz, and R. M. Enns. 2002. Trace mineral impact on reproductive performance, immune response, and calf performance in grazing beef cattle. J. Anim. Sci. 80(Suppl. 2): 117.
- K. L Dorton, L. R. Johnson, and T. E. Engle. 2002. Dietary copper alters basal and stimulated lipolysis of subcutaneous adipose tissue in finishing steers. TEMA 11:104.
- Rhoads, A. R., T. L. Stanton, T. E. Engle, and C. V. Kimberling. 2002. Effects of concentration and source of trace minerals on performance, immunity, mineral and lipid metabolism and carcass characteristics of beef steers. J. Anim. Sci. 80(Suppl. 2): 134.
- Flatt, W. R., T. L. Stanton, D. Schutz, J. Davis, and T. E. Engle. 2002. Effect of salt level on growth performance, carcass characteristics, cost of gain and manure salinity on finishing beef steers. J. Anim. Sci. 80(Suppl. 2):142.
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Progress 01/01/01 to 12/31/01
Outputs
The immune system is affected by both genetic and environmental factors. Trace minerals such as copper (Cu) zinc, selenium, and chromium are required for proper growth, immune function and reproduction in cattle. Typically these minerals are fed in excess to compensate for decrease in feed intake observed in weaned calves arriving to the feedlot. Thus resulting in excess mineral excretion by the animal. Heavy metal contamination of soil and ground water in areas of livestock concentrations is currently or will soon be monitored. The government will set contamination limits and regulate the amounts of these metals being fed to animals. The allowable amounts of these elements may not be determined by the animal's needs, but by waste content. Therefore, in order to minimize excretory losses of metals, sources providing better utilization to the animal must be found. In order to do this, criteria of mineral adequacy and availability must be established using
immunological, hormonal, and biochemical indices. Forty-eight Angus weaned steers, weighing approximately 230 kg were used. Steers were randomly assigned to individual pens and allotted to one of five treatments based on body weight and liver Cu status. Treatments consisted of: 1) Control (no supplemental Cu), 2) 10 mg of Cu per kg DM from Cu sulfate, 3) 20 mg of Cu per kg DM from Cu sulfate, 4) 10 mg of Cu per kg DM from Availa Cu, and 5) 20 mg of Cu per kg DM form Availa Cu. Steers were fed a growing diet for 56 days and then switched to a finishing diet for 144 days. Immunological measurements were obtained from steers throughout the growing and finishing phases. At the end of the finishing phase, steers supplemented with 10 mg Cu per kg DM from Availa Cu had heavier (P less than 0.01) body weights and tended to have greater ADG and higher ADFI than steers supplemented with 10 mg Cu per kg DM from Cu sulfate. Control steers tended to have lower (P less than 0.06) ADFI than Cu
supplemented steers. Initial liver Cu concentrations were similar (P greater than 0.15) across treatments due to experimental design. On d 56 of the growing phase and d 112 of the finishing phase, control steers had lower (P less than 0.01) liver Cu concentrations than steers supplemented with Cu and steers supplemented with 20 mg Cu per kg DM had higher (P less than 0.01) liver copper concentrations than steers supplemented with 10 mg Cu per kg DM. On d 112, steers supplemented with 20 mg Cu per kg DM from Availa Cu had higher liver Cu concentrations than steers supplemented with 20 mg Cu per kg DM from Cu sulfate, indicating a difference in bioavailability between the two sources. Steers supplemented with 20 mg Cu/kg DM had higher (P less than 0.04) antibody titers to OVA than steers supplemented with 10 mg Cu per kg DM. On both d 14 and d 21 post injection, steers supplemented 20 mg Cu/kg DM from Availa Cu had higher (P less than 0.03) antibody titers to OVA than steers
supplemented with 20 mg Cu per kg DM from Cu sulfate.
Impacts
This experiment demonstrates a difference in availability of different sources of copper fed to cattle. An increase in the availability of copper could potentially help to minimize excretory losses of the metal, therefore, helping to reduce metal contamination of soil and ground water in areas of livestock concentrations.
Publications
- Engle, T. E., and Spears, J.W. 2001. Performance, carcass characteristics, and lipid metabolism in growing and finishing Simmental steers fed varying concentrations of copper. J. Anim. Sci. 79:2920-2925.
- Engle, T. E., Fellner, V., and Spears, J.W. 2001. Copper status, serum cholesterol concentrations, and milk fatty acid profile in Holstein cows fed varying concentrations of copper. J. Dairy Sci. 84:2308-2313.
- Armstrong, T. A., Spears, J.W., Engle, T.E., and See, M.T. 2001. Effects of pharmacological concentrations of dietary copper on lipid and cholesterol metabolism in pigs. Nutr. Res. 21:1299-1308.
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Progress 01/01/00 to 12/31/00
Outputs
Inquires into livestock's contribution to and potential for mitigation of greenhouse gases emphasize methane produced from enteric and manure sources and frequently ignore nitrous oxide and carbon dioxide, potentially important contributors. Inputs to and outputs from US and NZ dairy production systems, varying particularly in intensity of pasture usage and lagoon disposal of manure, were collected to allow calculation of methane, nitrous oxide, carbon dioxide and total carbon dioxide equivalent (CO2eq) emissions per unit of product. Federal, state and commercial sources were consulted to provide herd and farm characteristics (e.g. weights, gains, milk, calving percent, mortality, diet composition, manure management, facilities, etc) and cropping practices (yields, fertilizer, pesticide, irrigation, equipement, etc). Spreadsheets were constructed to calculate all greenhouse gas related processes and product output to the farm gate. Methane, nitrous oxide and carbon
dioxide emission factors and equivalents were estimated from specific literature sources when available or if not, from IPCC as default values. Cows produced from 9000, 7200, and 3400 kg of milk/yr., with zero (CA), 31 (WI), and 83% (NZ) pasture usage. Enteric methane estimates ranged from .38 to .61 kg CO2eq/kg milk, inversely proportional to the amount of milk/cow. Manure methane emissions were very high in the CA system (.39 kg CO2eq/kg milk) due to use of anaerobic lagoons for disposal of half of the manure. Nitrous oxide emission estimates were much lower in the US systems (.36 and .43) than in the NZ system, which produced .81 kg CO2eq/kg milk, reflecting the higher production/cow and lower dietary N in the US. Conversely, the CO2 emissions/milk in NZ from CO2 producing power sources were half or less those of the US reflecting the predominant use of hydroelectric generated power in NZ. Overall, emissions of 1.5 and 1.4 kg for US systems found the higher productivity advantage
being overshadowed by the higher emissions related to manure disposal method, but both with moderately less than NZ with 1.7 kg CO2eq/kg milk. Non-methane greenhouse gas emissions ranged from 50 to 66 % of the total and should be considered when examining mitigation strategies.
Impacts
Nitrous oxide is an important or major contributor to greenhouse gas equivalents produced by livestock systems. Intensive grazing system limit milk production per cow and can yield large excesses of N in the diet, both of which elevate GHG emissions per product. Consideration of these emissions can allow CO and/or US milk production with less environmental impact.
Publications
- Gibbs, MJ, Conneely,C., Johnson,D.E., Lasse,K.R., and Ulyatt,M.J. 2000. Methane emissions from enteric fermentation. White paper for expert group meeting on good practice in inventory preparation, IPPC.
- Phetteplace, H. W., Johnson,D.E., and Seidl,A. 2000. Greenhouse Gas Emissions from Feedlot and Dairy Systems, Proc. High Plains Pilot Project, Denver, CO, December 2000, p 46-54.
- Johnson, D. E., Phetteplace,H., and Ulyatt,M. 2000. Variations in proportion of methane of total greenhouse gas emissions from US and NZ dairy production systems. Proc. 2nd International Methane Mitigation Conference, Novosibirsk, Russia, USEPA, p 249-254.
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Progress 01/01/99 to 12/31/99
Outputs
Inputs and outputs to 5 beef cow-calf, 2 feedlot and 2 dairy production systems in diverse, high volume US counties were described to allow calculation of methane, nitrous oxide, carbon dioxide and total carbon dioxide equivalent (CO2eq) emissions per unit of product. Federal, state and commercial sources were consulted to provide herd characteristics (e.g. weights, gains, milk, fertility, age at first calving, calving percent, mortality, etc), diet composition, manure management and cropping practices (yields, fertilizer, pesticide, irrigation, etc). This information was used to construct spreadsheets to calculate all greenhouse gas related processes and product output to the farm gate. Feed consumption was predicted using NRC net energy requirements for each class of cattle. Methane, nitrous oxide and carbon dioxide emission factors and equivalents were estimated from specific literature sources when available or if not, from IPCC as default values. Productivity of
the beef herds including feedlots varied from 320 to 401 kg live weight sold (culls and fed beef) per cow, with enteric methane emissions of 6.0 and 5.4 kg, CO2eq/kg weight sold for these productivities. Nitrous oxide sources within beef system varied considerably, but overall emission estimates were consistent; 4.7 +-0.2 kg, CO2eq/kg live weight sold. Estimates of total greenhouse gas were also consistent across these beef systems, averaging 11.5 +-0.2 kg CO2eq/kg sold. On average, methane and nitrous oxide made up 50 and 40 percent of the total. Comparisons within phases of beef production showed lower stocker and feedlot emissions of 2.5 to 3.9 kg CO2eq/kg produced reflecting the lessor cow maintenance subsidies and depressed fractional methane loss with high grain feedlot diets. The dairy simulations were cows producing 7600 kg of milk/yr., with zero pasture (California) and a 6065-kg of milk/cow (Wisconsin) system. Enteric methane estimates were .42 and .43 kg CO2eq/kg milk for
these systems while manure methane emissions were .38 and .04 kg/kg milk. Nitrous oxide emission estimates of .45 and .46 kg CO2eq/kg milk again favored the higher production/cow. Overall, emissions of 1.5 and 1.3 kg for these systems found the higher productivity advantage being overshadowed by the higher emissions related to manure disposal method. Enteric methane emissions were 28 to 34 percent of total and nitrous oxide were 30 to 37 percent of total for these milk production systems. Dairy-beef from culls plus fed non-replacements, as an auxiliary to milk carries a relatively small emissions cost of approximately 3.2-kg CO2eq per kg product. Non-methane greenhouse gas emissions from cattle production range from 50 to 55 percent of the total and should be considered when examining mitigation strategies.
Impacts
Livestock producers will need to consider sources of greenhouse gases in addition to methane, particularly nitrous oxide when evaluating environmental impacts of the production system.
Publications
- Jarosz, M, J. and Johnson, D.E. 1999. Methane losses and metabolizable energy value of fibrous grain by-product feeds. Beef Program Report, 17:63-68.
- Phetteplace, H. and Johnson, D.E. 1999. Greenhouse gas emissions from US beef production systems. Beef Program Report, 17:33-38.
- Phetteplace, H.Johnson, D.E. and Seidl, A. 1999. Greenhouse gas emissions from US beef and dairy production systems. J. Anim. Sci. 77:(Suppl. 1, Abstr.).
- Johnson, D.E., Phetteplace,H., Ward, G., and Seidl, A. 1999. Livestock system greenhouse gases. Proc. Ruminant Livestock Efficiency Program. U.S. Environmental Protection Agency: Washington, D.C
- Phetteplace, H.W., Johnson, D.E., and Seidl, A.F. 1999.Greenhouse Gas Emissions from Beef and Dairy Livestock Systems in the United States. Proc. International Conference on Mitigation of Agricultural Sources of Greenhouse Gases, Stuttgardt, Germany.
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Progress 01/01/98 to 12/31/98
Outputs
In response to U. S. and global concerns, our livestock - environmental interactions research has changed to evaluation of factors affecting the greenhouse gas production from livestock and/or livestock systems. Beginning with methane emissions, we are examining nitrous oxide, carbon dioxide from fuels and carbon sequestration in soils to provide a total system analysis of emissions and potential tradeoffs. The GHG emissions to produce milk in the U. S., for example, are estimated at 1590 g of CO2 equivalent per kg of milk. Enterically produced methane is 33 and manure methane 17% of this total, leaving 50% from other sources, e.g., fertilizer, fuel, soil-C, etc. The use of best management practices for crop production could reduce the total by an estimated 14% through increased soil-C sequestration. Increased use of pasture may increase these savings further. Usefulness of findings: This information will allow producers, industry or policy makers to better understand
livestock system impacts on environment and/or sustainability. Regional and system variations in emissions per product can be compared. The effects of changingrate of productivity, pasture usage, and methane mitigation strategies can then be evaluated.
Impacts
(N/A)
Publications
- Johnson, D. E. and Bernal, G. 1998. Diet energy requirements of growing Holsteins. J. Dairy Sci. 81:840-845 Johnson, D. E., Phetteplace, H., Ward, G., and Seidl, A. 1998. Livestock system greenhouse gases. Proc. Ruminant Livestock Efficiency Program. Ann. Meeting, Athens, GA, US-EPA, Wash.
- Jarosz, M.J. and Johnson, D.E. 1998. Methane losses and metabolizable energy value of fibrous grain by-product feeds. J. Anim. Sci. 76 Suppl. 1:304. Donald E Johnson 209 Anim. Sci. Colo State Univ. Ft Collins, CO 80523 (970-491-7833, fax-5326)
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Progress 01/01/97 to 12/31/97
Outputs
Open-lot fed cattle gain less in winter than other seasons while consuming equal amounts of feed with ensuing economic penalty. This experiment investigated a potential for changes in rat hepatocyte mitochondrial proton leakage to respond to cold ambiency (24 vs. 10C) shifting maintenance energy requirements and thermogenesis. Cold exposure decreased proton leakage of lean, although not of obese rats. Implications: The decreased mitochondrial proton leakage of the normal lean animals, opposite to theorized, indicates this is not to be a cold-thermogenic mechanism, but possibly a defense of vital ATP generation in response to cold. It is unlikely that this mechanism will help to explain excess heat loss by winter fed animals. Nevertheless, the changes in mitochondrial proton leakage with genotype may allow prediction of and/or selection for animals with lower maintenance requirements. (1 GRA)
Impacts
(N/A)
Publications
- JOHNSON, D.E., G.M. WARD and G. BERNAL. 1997. Chapter 32. Biotechnology mitigating the environment effects of dairying. In: Biotechnology in Agric. Series, Welch, R. et al. Edit., CAB International, pp. 497-511.
- RAMSEY, J.J., D.E. JOHNSON and K.A. JOHNSON. 1996. Metabolic rate, organ mass, and mitochondrial proton leak variations in lean and obese rats. Biochem. Physiol. 113:461.
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Progress 01/01/96 to 12/30/96
Outputs
Hide samples of Colorado winter fed cattle were collected, cleaned and shipped frozen to Cornell University where, through the cooperation of Dr. Hillman, energy flux properties were measured with a specially constructed forced-convection calorimeter. Summarized, heat transfer through the hair coat resulted in a 30 W/m2 energy loss to a clear night sky (-28 degrees C) condition. A separate investigation measured surface temperatures on a live cattle in the feedlot during a clear night sky. Hair surface temperature averaged 7 degrees C (ranging from 2 to 10 degrees C), which was moderately higher than those from the forced calorimeter assessment. These differentials between hair surface and sky can produce larger heat losses to the cold night sky and may explain a significant component of suppresed winter gains by open-lot, Colorado-fed cattle.
Impacts
(N/A)
Publications
- Hillman, P.E., K. Gebremedhin and D.E. Johnson. 1996. Effect of heat loss to cold clear skies on daily weight gains of cattle in winter feedlots. Presentation paper #964120, ASAE Annual Meeting.
- Johnson, D.E. and G.M. Ward. 1996. Estimates of animal methane emissions. Environ. Monitoring Assessment. 42:133-141.
- Johnson, D.E., G.M. Ward, and J. J. Ramsey. 1996. Chpt.15. Livestock methane: Current emissions and mitigation potential. In: Nutrient Mgmt. of Food Animals to Enhance and Protect the Environment. E.T. Kornegay, ed. CRC Press, pp. 219-234.
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Progress 01/01/95 to 12/30/95
Outputs
Conductance of heat across the skin and hair of Colorado cattle has been evaluated using a forced convection calorimeter (in a cooperative investigation by Dr. Hillman at Cornell). Summer and winter samples of 35 fresh hide samples collected over two years found large variations in conductance (W/(m2deg.C)) between individual animals and/or hide locations (6 to 50W sensible and 18 to 120W total heat). Pelt loft was also variable (2 to 7 mm). Winter pelts were only marginally less conductive than summer and generally revealed poor resistance to cold stress as adapted to Colorado climates. An attempt to collect weather data to define nighttime cooling from exposure to long wave radiation to the cold night Colorado sky has been abandoned due to calibration problems and equipment malfunction. Available estimates support the importance of energy losses by this route.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Summer and winter samples of hides from fat cattle at slaughter in Colorado havebeen evaluated by forced-convective calorimetry (collaborative measurements by Cornell University). Thermal conductance W/(m squared x degrees C) varied by 5-fold by area sampled and approximately 3-fold by animal. The loin area was the most reflective of the overall animal, however, check and/or belly samples, obtainable without serious economic damage to the hide, are reasonable alternatives. Typical conductance of hides ranged from 28 to 60 for summer fed cattle and from 18 to 39 W/(m squared x degrees C) for winter fed cattle. These results support the hypothesis that lowered winter gains with equal feed intake by Colorado open-lot fed cattle are responding to nighttime cold loads. Monitoring or predicting longwave radiant heat loss may help producers determine seasonal feed and economic efficiency responses.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
Ten months of observations every ten seconds were used to generate weekly averages of temperature, humidity, short- and long-wave radiation. A sky-chill index was calculated as the average watt/m2-days during which negtive long wave radiation balances occurred. The weekly mean temperatures ranged from -13 C to 26 C. The average watt-days of negative reading radiations for the sky chill averaged -30.4 for the three winter months, January-February, ranging from -10 to -50 during this period. The negative losses to the sky were the highest during June, where they ranged from 64 to 89 (negative watt/m2-days). Given the assumption that the animal was at or below its lower critical temperature during the winter period, these negative radiant energy flows can account for approximately 0.25 kg depression in average daily gain. The greater negative sky chills during the summer months assist in alleviating heat stress. Samples of cattle hides taken across the year showed thermal
resistances of 53 and 43 w/(m2 C) for summer and winter fed cattle (measured collaboratively by Cornell University).
Impacts
(N/A)
Publications
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Progress 01/01/92 to 12/30/92
Outputs
Climate records, including longwave sky and earth radiation are being recorded at the CSU Research Feedlot for comparison to cattle performance and apparent energetic efficiency. The pyrradiometer total long and short wave radiation sensor is being calibrated by shading technique and water body temperature differential. Longwave radiation to the nightsky is estimated to reach a loss of .060 kw/m2, while daytime solar influx reaches .950 kw/m2. The readings will be compared to NASA EOS data for a Colorado Quadrant.
Impacts
(N/A)
Publications
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Progress 01/01/91 to 12/30/91
Outputs
A climate monitoring system has been installed and is reading xC, RH, wind speedand direction, short wave radiation, total upward and total downward radiation each 10 sec. and the average recorded every 20 minutes. Samples of 8 steer hides (15 x 30 cm) have been taken from steers slaughtered in Colorado in January and July. These samples have been evaluated in a forced-convection calorimeter at Cornell University for assessment of evaporative, convective and radiant heat loss across the fur. Conductance (W/(M}yC)) was decreased from 9.9 in summer to 6.3 in winter slaughtered cattle. The principle difference in hair properties was a 69% increase in length of winter hair.
Impacts
(N/A)
Publications
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Progress 01/01/90 to 12/30/90
Outputs
Performance records from 315,524 yearling cattle fed over eight years (1977-1985) in commercial open-lots in North Central Colorado were examined for seasonality and relationship to climate descriptors. Daily feed intake (Table 1) averaged the same in winter months as in the summer (8.4 vs 8.5 kg DM/hd) with a tendency to slightly higher intakes in the fall season (+2%). The cattle gained 150 g/d less in the winter than in summer and at intermediate rates during other seasons. A moderate association between gain and wind chill temperature was noted: ADG = 1.20 + .0088 (EAT), r} = .33. The apparent net energy required for maintenance (NEm) was approximately constant for all seasons except summer, which averaged about 21% lower. A weak association was found between apparent maintenance requirement and EAT: r} = .18. These field data support prior conclusions that open-lot cattle gain less but do not eat more in cold seasons in Colorado.
Impacts
(N/A)
Publications
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Progress 01/01/89 to 12/30/89
Outputs
Thirty-two gestating heifers carrying split embryos have been placed on control or restricted energy regimens. Heat producion will be measured by indirect respiration calorimetry to determine the effect of energy restriction during gestation on the basal metabolic rate of the newborn calf during the first day or two of life.
Impacts
(N/A)
Publications
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Progress 01/01/88 to 12/30/88
Outputs
A dynamic model has been developed which is designed to evaluate effects of short term acute cold stress resulting from diurnally fluctuating thermal environments and its' relationship to decreased performance in beef cattle housed outdoors in winter. Heat production of an animal is balanced with heat loss in an hourly time step using an iterative procedure which adjusts physiological responses in a prioritized sequence. Unique to this model is the consideration of the large deviation of the radiant environmental temperature, i.e. the cold night sky, from that of the ambient thermal environment. The model suggests that the radiant heat losses are an important component of winter environmental stress in Colorado feedlot cattle.
Impacts
(N/A)
Publications
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Progress 01/01/87 to 12/30/87
Outputs
Maintenance related research from prior experiments was analyzed and summarized and another trial completed. A uniformity trial (similar environment) was conducted utilizing 10 pairs of identical 9-mo old demi-embryo beef calves to evaluate variances between (b) and within (w) twin pairs for fasting heat production (FHP) and maintenance heat production (MHP) using indirect respiration calorimetry. The model used to evaluate MHP and FHP included comparision of fixed effects of breed and sex and the random effect of pair. The comparison of b and w values (110.2 and 45.4) for MHP revealed a substantial reduction (P<.01) in w due to inclusion of pair in the model. The w for FHP, however, was not reduced (P<.10) by inclusion of the pair term. Unexpectedly, females had higher (P<.05) FHP than males. Pair means for MHP ranged from 99.6 to 145 kcal/wt, while within pair differences ranged from 1.3 to 18.2 kcal/wt. Pair means for FHP ranged from 73.8 to 90.9 kcal/wt. The
reduction in w due to pair effects for MHP but not for FHP suggests that the experimental advantage to using monozygous twins exists only when measuring metabolic rates in response to diets and not when measuring metabolic rates independent of diet. Estimated heritability for MHP was .71 +/- .17. Heritability was not calculable for FHP.
Impacts
(N/A)
Publications
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Progress 01/01/86 to 12/30/86
Outputs
A dynamic simulation model was developed to evaluate several aspects of thermal acclimation effects on growing beef cattle intake and energy use under Colorado open lot climatic conditions. Daily deviations in temperature from a running average depressed dry matter intake, but was offset by cold stimulation as roposed as a NRC model factor. Major mathmatical discrepancies were shown to exist in published thermal effect models. Colorado climate for the example winter period induced a 16.4% increase in maintenance requirement and a 10.7% decrease in live weight gain due to adjustments in basal metabolic rate which was the dominant effector of change in performance by existing published models. In a second experiment utilizing split embryo twins, restricted protein nutrition of the dam during the last one-third of the gestation period was shown to decrease the basal metabolic rate of the baby calf by approximately 12% when measured between five and thirteen hours of
age. Additionally, low birth weight calves regardless of prior dam nutritional treatment were shown to have lower metabolic rates. The data suggests that either restricted protein nutrition of the dam during gestation or light birth weights of the calves may compromise neonatal thermogenesis and thus compromise survival in cold environments.
Impacts
(N/A)
Publications
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