Source: MICHIGAN STATE UNIV submitted to
NUTRITION AND MANAGEMENT REGIMES FOR EFFICIENT FEED UTILIZATION BY BEEF CATTLE
Sponsoring Institution
State Agricultural Experiment Station
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0175273
Grant No.
(N/A)
Project No.
MICL03360
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Aug 1, 2007
Project End Date
Jul 31, 2012
Grant Year
(N/A)
Project Director
Buskirk, D.
Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824
Performing Department
ANIMAL SCIENCE
Non Technical Summary
The primary determinant of beef quality and consumer acceptability is the amount of intramuscular fat deposited within muscles. Insufficient intramuscular fat has been documented as the beef industryAEs largest quality challenge. The purpose of this work is to better understand fat development in beef cattle and determine optimum management regimens to control fat deposition.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3023310101010%
3053310102010%
3083310101060%
3153310106020%
Goals / Objectives
The goal of our research is to increase our understanding of factors that affect the deposition of intramuscular and subcutaneous fat in beef cattle. This understanding will provide us knowledge necessary for development of management regimens that result in efficient feed utilization and high quality beef. The proposed research will be aligned with two working hypotheses. Hypothesis 1: Non-abrupt methods will reduce acute stress associated with weaning and will result in decreased intramuscular fat deposition in beef calves. Our objectives are to: 1) determine the effects of three different weaning methods on physiological and behavioral indicators of stress, and 2) determine the subsequent effects of these weaning methods on intramuscular fat deposition, and 3) determine if other weaning methodologies affect stress and fat deposition. Hypothesis 2: Treatment with ibuprofen, a known peroxisome proliferator activated receptorγ2 ligand will preferentially increase intramuscular fat compared to subcutaneous fat in beef cattle. Our objectives are to: 1) examine the pharmacokinetics of ibuprofen in growing cattle, 2) determine the effect of ibuprofen supplementation on subcutaneous and intramuscular fat accretion, and 3) determine optimum delivery methods, timing, duration, and dosage of ibuprofen to elicit desirable beef quality changes.
Project Methods
Effect of non-abrupt weaning methods on stress in beef calves and resulting beef quality Approximately 400 steer and heifer calves will be used to determine the effects of non-abrupt weaning methods on stress and subsequent beef quality. Calves from the Lake City Experiment Station, Lake City, MI and the U.P. Experiment Station, Chatham, MI herds will be used. Body weight will be taken on d -14 and used to allot calves to treatment. Treatments will consist of 1) an abrupt weaned control; 2) fenceline weaning; and 3) 2-stage weaning. Abruptly weaned calves will be separated from their dams on d 0. Dams will be relocated to non-adjoining pastures out of visual and hearing range of their calves. Fenceline weaned calves will be weaned on d 0 and their dams will be pastured in an adjoining pasture allowing fenceline contact with their calves. Two-stage weaned calves will have a plastic non-suckling nose flap placed on d 0. Two-stage weaned calves will remain with their dams until d 5 at which time the nose flap will be removed and their dams will be relocated to non-adjoining pastures. Calves will be weighed on d -14, 0, 5, 14, 28, and 42., and blood will be obtained by jugular venapuncture on d 0, 5, 14, 28, and 42, stored at 4 C until plasma is harvested and stored at −20 C until laboratory analysis. Plasma haptoglobin concentrations will be determined using radial immunodiffusion, and cortisol will be determined by enzyme immunoassay. Calves will be transported to the MSU Beef Cattle Teaching and Research Center to be finished. Cattle will be grouped by herd location, gender, weaning treatment and allotted by weight to pen. Steers will be fed a common finishing diet, in which, percentage of concentrate will be increased step-wise until steers are adapted. Steers will be harvested after a constant number of days on feed, and carcass measurements will be obtained. Effect of ibuprofen treatment on intramuscular and subcutaneous fat in beef cattle Six steers will be used to determine the pharmacokinetics of ibuprofen in growing beef cattle at the MSU Beef Cattle Teaching and Research Center. When steers reach a mean body weight of approximately 300 kg, they will be assigned to one of two treatments in a crossover experimental design. Treatments will include 1) ibuprofen as a sterile solution to be administered intravenously at the rate of 25 mg/kg body weight, and 2) ibuprofen as a bolus of 200-mg tablets in 3 gelatin capsules to be administered with an esophageal bolusing tube. This dosage is expected to result in serum concentrations of ibuprofen comparable to those found to preferentially stimulate intramuscular preadipocytes in vitro. After a one week washout period, treatments will be reassigned, and the protocol repeated. Blood will be collected at 0, 0.75, 1.5, 3, 6, 12, and 24 h after intravenous and oral treatment by venipuncture and allowed to clot. Serum will be harvested and stored at -20 C until analysis. Serum will be thawed at approximately 20 C immediately prior to HPLC analysis for ibuprofen concentration.

Progress 08/01/07 to 07/31/12

Outputs
OUTPUTS: EXPERIMENTS: Bovine intramuscular, subcutaneous, and perirenal preadipocytes express similar glucocorticoid receptor isoforms, but exhibit different adipogenic capacity. Ibuprofen preferentially enhances adipogenesis in bovine intramuscular preadipocytes when compared to subcutaneous preadipocytes. Performance of beef calves weaned by traditional, fenceline, and two-step methods. Behavior of beef calves weaned by traditional, fenceline and two-step methods. Effect of level of pasture supplementation with dried distillers grains with solubles on performance and carcass traits of beef steers. Effect of glycerin as a dietary supplement on the performance and carcass characteristics of beef cattle. FIELD DAYS: U.P. Experiment Station Field Day. Can We Wean Beef Calves Without Stress July. 26, 2008. Chatham, MI. Lake City Experiment Station Field Day. To Bawl or not to Bawl Exploring Weaning Options. Aug. 23, 2008. Lake City, MI. SEMINARS/TALKS: Effects of non-abrupt weaning methods for beef calves on performance and immune function. Research update for Growing U.P. Agriculture Association. March 6, 2007. Chatham, MI. Distillers grains as feedstuff for beef cattle: Calves, developing heifers, stockers, and cows. Bovine Health Lecture featuring the Cow/Calf Producer. October 27, 2007. E. Lansing, MI. Effect of level of pasture supplementation with dried distillers grains with solubles (DDGS) on performance and carcass traits of beef steers. MSU Ethanol Co-product Forum. October 3, 2007. E. Lansing, MI PRODUCTS: The following provisional patent was converted to a PCT Application (international) designating the US in 2007. "Methods and compositions for modulating muscle fat in livestock" PARTICIPANTS: Dr. Janice Siegford - Dr. Siegford has been working with me on calf weaning methods. I have relied on her expertise for observing, recording, and analyzing animal behaviors. Dr. Matt Doumit - Dr. Doumit and I have teamed to develop the in vitro system for bovine preadipocyte differentiation. His expertise was used in culutre methods and analisys of differentiation endpoints. Dr. Steven Rust - Dr. Rust was consulted on animal performance measures of cattle while at the Beef Cattle Teaching and Research Center and experimental design issues and logistics. TARGET AUDIENCES: Objective 1 Evaluation of beef calf weaning methods Target audience is beef producers. Beef producers were primarily reached through presentation at field day events. Objective 2 Evaluation of bovine stromal-vascular cell differentiation Target audience is growth and development research scientists. Scientists were primarily reached through publication in the Journal of Animal Science. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
BEEF CALF WEANING METHODS The objectives of this research were to determine the effect of three different methods of weaning beef calves on 1) post-weaning weight gain, 2) haptoglobin concentration (reflective of inflammation response), 3) finishing performance, and 4) carcass traits. Over two years, 466 beef calves were allocated to one of three weaning method treatments: 1) abrupt-weaned (AW); 2) fenceline-weaned (FW); and 3) two-step-weaned (TW). On day 0, all calves were assigned to pastures and prevented from nursing their dams. Dams of AW calves were moved to remote pastures, dams of FW calves were moved to adjoining pastures with fenceline contact, and TW calves had a nose flap fitted. On day 5, TW calves had the nose flap removed, and all dams were moved to remote pastures. Although FW calves gained more weight and had lower haptoglobin levels shortly after weaning, there were no differences in post-weaning weight gain to day 42, and no finishing performance or carcass trait differences due to weaning method. Two-step-weaned calves showed less behavioral stress as measured by reduced bawling, and reduced steps taken in the days immediately following weaning. Although the TW and FW methods resulted in diminished measures of behavioral stress, they did not result in sustained performance differences compared to traditional weaning. BOVINE PREADIPOCYTE DIFFERENTIATION Understanding preadipocyte differentiation in economically important adipose depots will facilitate efforts to selectively increase intramuscular (i.m.) lipid accretion in cattle. Our objectives of these experiments were to 1) develop an in vitro cell culture system for differentiation of bovine stromal-vascular (S-V) cells (presumed to be preadipocytes), permitting examination of differentiation in intramuscular (i.m.) and subcutaneous (s.c.) bovine S-V cells, 2) compare differentiation of bovine i.m. and s.c. S-V cells in response to a glucocorticoid (dexamethasone) and a peroxisome proliferator-activated receptor γ agonist (troglitazone), and 3) determine if glucocorticoid receptor expression differs among these cell types. We successfully isolated and cultured S-V cells from bovine i.m. and s.c. adipose depots. Our data revealed that bovine S-V cells are capable of differentiation in response to combinations of insulin, serum lipids, dexamethasone, and troglitazone. Most importantly, inherent differences in the capacity to differentiate exist between adipogenic bovine i.m. and s.c. S-V cells (s.c. cells are much more adipogenic than i.m. cells). Dexamethasone and troglitazone were additive in enhancing differentiation, however, no differential effects of these compounds on the differentiation of s.c. and i.m. cells were detected. Our data suggests that differences in adipogenic activity among bovine i.m. and s.c. S-V cells are not related to glucocorticoid receptor abundance or function. Understanding preadipocyte differentiation in economically important adipose depots will facilitate efforts to selectively increase intramuscular (i.m.) lipid accretion in cattle.

Publications

  • Grant, A. C., G. Ortiz-Colon, M. E. Doumit, R. J. Tempelman and D. D. Buskirk. 2008. Differentiation of bovine intramuscular and subcutaneous stromal-vascular cells exposed to dexamethasone and troglitazone. J. Anim. Sci. 86:2531-2538.
  • Grant, A. C., G. Ortiz-Colon, M. E. Doumit, and D. D. Buskirk. 2008. Optimization of in vitro conditions for bovine subcutaneous and intramuscular preadipocyte differentiation. J. Anim. Sci. 86:73-82.
  • Ortiz-Colon, G., A. C. Grant, M. E. Doumit, and D. D. Buskirk. 2009. Bovine intramuscular, subcutaneous, and perirenal stromal-vascular cells express similar glucocorticoid receptor isoforms, but exhibit different adipogenic capacity. J. Anim. Sci. (Pending).


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Four-hundred sixty-six steer and heifer beef calves (165 days of age) were used to determine the effects of non-abrupt weaning methods on postweaning performance, immune function, feedlot performance, and carcass traits over 2 years. Calves were from the MSU Lake City Agricultural Experiment Station, Lake City, MI and the U.P. Agricultural Experiment Station, Chatham, MI herds. Calves were allotted to treatment by gender and weight (d -14). Treatments were 1) abrupt weaned (AW; control); 2) fenceline weaned (FW); and 3) two-stage weaned (TW). On d 0, all calves were assigned to one of nine pastures and prevented from nursing their dams. Dams of AW calves were moved to remote pastures out of visual and hearing range of their calves, dams of FW calves were moved to adjoining pastures with fenceline contact, and TW calves had a plastic nose flap fitted. On d 5, dams of FW and TW calves were relocated to remote pastures out of visual and hearing range of their calves, and TW calves had their nose flap removed. The nose flaps caused pressure lesions on the septum of most calves. Calves were weighed on d 0, 5, 14, 28, 42 and 43. Blood haptoglobin concentration was monitored over time during year 1 of the experiment to assess stress caused by weaning treatment. Following brief backgrounding, 311 of the calves were transported to the Beef Cattle Teaching and Research Center, E. Lansing and allotted by weaning treatment, gender, and weight to pens with 6 to 8 animals each. Cattle were fed a common diet, in which, percentage of concentrate was increased step-wise until cattle were adapted to a finishing diet. Cattle were harvested at a commercial processing plant and complete carcass data was obtained. There were no significant differences in calf weights due to weaning treatment through d 42. Although FW calves had greater (P < 0.001) average daily gain between d 0 and 14 than AW and TW calves, calves from all treatments had similar overall average daily gain by d 28 which was maintained throughout the experiment. Haptoglobin concentrations in blood were elevated on d 5, and were highest in TW calves followed by AW and lowest in FW calves (P < 0.001). It is possible that the nose flaps were causing an inflammatory response in TW calves. Haptoglobin concentrations returned to baseline levels for all treatments by d 14. All treatments experienced a rise in haptoglobin level on days 28 and 42. Initial and final body weights during finishing were not different among weaning treatments (P > 0.82), nor were there differences in average daily gain (P = 0.99). There were also no significant differences in the percentage of calves that received one, or two or more medical treatments during finishing. None of the carcass traits measured were significantly different among treatments. PARTICIPANTS: Daniel D. Buskirk, Ph.D. Principle Investigator responsible for project design, conduct, analysis, and reporting. Janice M. Siegford, Ph.D. Aided in project design, conduct, and analysis. Dr. Siegford also conducted behavioral observations, recording, analysis, and reporting. This project included training opportunities for two undergraduate students, B. A. Wenner and M. K. Sharra. TARGET AUDIENCES: The results of this research project are directed at beef producers and Extension educators. D. Buskirk and J. Siegford conducted two pasture walks for producers during the weaning portion of the project at the Lake City and Upper Peninsula Experiment Stations. A published report of the results was also distributed to the producer members of the Lake City Experiment Station Advisory Committee and the Growing U.P. Agriculture Association.

Impacts
Although fenceline weaned calves had improved performance through two weeks postweaning, by three weeks following weaning all calves had equalized their weight gains. Because calves weaned by the two stage method appeared to have less behavioural indicators of stress it may be that the principle of the two-stage method to reduce weaning stress is sound, but the nose-flaps used in this experiment caused significant irritation thereby causing stress as indicated by blood haptoglobin concentrations. Field days held at both the Lake City and Upper Peninsula Agricultural Experiment stations reviewed with producers the benefits and drawbacks of the three weaning methods.

Publications

  • Buskirk, D. D., J. M. Siegford, and B. A. Wenner. 2007. Performance of beef calves weaned by traditional, fenceline, and two-step methods. J. Anim. Sci. 85(Suppl. 1):542 (Abstr.).
  • Siegford, J. M., D. D. Buskirk, and M. K. Sharra. 2007. Behavior of beef calves weaned by traditional, fenceline and two-step methods. J. Anim. Sci. 85(Suppl. 1):365 (Abstr.).


Progress 01/01/06 to 12/31/06

Outputs
The objectives of these experiments were to determine if intramuscular (IM) and subcutaneous (SC) bovine preadipocytes differ in expression of peroxisome proliferator activated receptor &#947;2 (PPAR&#947;2) or in secretion of prostacyclin (PGI2), a presumptive endogenous PPAR activator. Preadipocytes isolated from IM and SC adipose tissues of three steers were propagated in culture and upon confluence were exposed to 0 or 25 nM dexamethasone (DEX) for 48 h. After exposure to differentiation media for an additional 10 d, cell lysates were subjected to PPAR&#947;2 immunoblot analysis, which revealed an immunoreactive band of 53 kDa. There was no interaction between DEX treatment and preadipocyte depot (P = 0.90) in the relative expression of PPAR&#947;2. Expression of PPAR&#947;2 was also equivalent between IM and SC preadipocytes (P = 0.39), and DEX did not affect PPAR&#947;2 abundance (P = 0.98). Heterogeneous preadipocytes isolated from a steer and clonal preadipocytes derived from a second steer were grown to confluence and exposed to 0 or 25 nM DEX for 48 h. Media were collected every 12 h for 48 h and assayed for the stable PGI2 derivatives 6&#8208;keto&#8208;prostaglandin F1&#945; (6k&#8208;PGF1&#945;) and 2,3&#8208;dinor&#8208;6&#8208;keto-prostaglandin F1&#945; (2,3d&#8208;6k&#8208;PGF1&#945;). After 12 d in differentiation media, glycerol&#8208;3&#8208;phosphate dehydrogenase (GPDH) analysis was performed. Intramuscular preadipocytes secreted more PGI2 derivatives than SC preadipocytes (P = 0.046) and DEX decreased secretion of the PGI2 derivatives equally in cells from both depots (P = 0.001). Although 25 nM DEX increased GPDH activity in both preadipocyte populations (P < 0.001), IM preadipocytes were less adipogenic than SC preadipocytes (P < 0.001). Exposure of clonal SC preadipocytes to 1 &#956;M cPGI2 tended (P = 0.06) to enhance differentiation over control conditions, and tended (P = 0.09) to increase the adipogenic enhancement stimulated by DEX. However, supplementation with 0.01 or 0.1 &#956;M cPGI2 did not increase differentiation (P > 0.65). Although ibuprofen (IBU), an inhibitor of PGI2 synthesis, did not affect adipogenesis in clonal SC preadipocytes (P = 0.99), 100 &#956;M IBU enhanced (P = 0.01) adipogenesis in the presence of DEX while an intermediate concentration (50 &#956;M) tended (P = 0.08) to enhance DEX effects. We conclude that adipogenic differences between IM and SC bovine preadipocytes are not explained by differences in PPAR&#947;2 expression or PGI2 secretion.

Impacts
Adipogenic differences between intramuscular and subcutaneous preadipocytes are not explained by differences in the expression of peroxisome proliferator&#8208;activated receptor gamma two (PPAR&#947;2), an important regulator of adipogenesis, or by differences in the secretion of a presumptive PPAR activator, prostacyclin. Consequently, adipogenic differences between intramuscular and subcutaneous preadipocytes may be a result of differences in the synthesis of a biologically relevant PPAR&#947;2 ligand that is not prostacyclin. Additional investigations with the aim of identifying this PPAR&#947;2 ligand(s) are warranted. An enhanced understanding of fat development in cattle will ultimately lead to ways in which we can manipulate overall fat content and composition in beef. This will result in highly palatable and healthful beef products.

Publications

  • Ortiz Colon, G. 2006. Investigation of adipogenic differences between bovine intramuscular and subcutaneous preadipocytes. Ph.D. Dissertation, Michigan State Univ. E. Lansing.


Progress 01/01/05 to 12/31/05

Outputs
We hypothesized that differences exist in glucocorticoid receptor (GR) expression among preadipocytes derived from bovine intramuscular (IM), subcutaneous (SC), and perirenal (PR) adipose tissue, and that dexamethasone (DEX) would have differing effects on adipogenesis of these cell populations. Preadipocytes isolated from IM, SC, and PR adipose tissues of two steers were propagated in culture and upon confluence were exposed to 0 or 250 nM DEX for 48 h. Cell lysates were subjected to GR immunoblot analysis and immunoreactive protein bands of 97, 62, and 48 kDa were detected. Relative to the &#946;-actin immunoreactive band, each GR protein signal was similar among preadipocyte populations (P > 0.50). Dexamethasone exposure decreased the abundance of the 97 and 62 kDa GR immunoreactive bands in preadipocytes from the three depots (P < 0.001), while the expression of the 48 kDa band was not affected (P = 0.96). Preadipocytes isolated from three steers were grown in culture, and upon confluence, were exposed to 0, 25, or 2500 nM DEX for 48 h, and differentiation media for an additional 10 d. Under all conditions the propensity to differentiate, determined by sn-glycerol-3-phosphate dehydrogenase (GPDH) specific activity and oil red O staining was PR > SC > IM (P < 0.05). There was no interaction between DEX level and adipose tissue depot for GPDH activity, (P = 0.99). Dexamethasone increased GPDH activity in all cells (P < 0.05), equally at 25 or 2500 nM (P = 0.45). However, when considering morphological assessment of differentiation, we found an interaction (P = 0.03) between DEX concentration and depot. Although PR preadipocytes showed an increase (P < 0.02) in the percentage of differentiated cells with increasing concentration of DEX, only 2500 nM DEX increased morphological differentiation in SC cells (P = 0.002). Furthermore, DEX did not significantly increase the percentage of differentiated IM preadipocytes (P > 0.27). In summary, cultured preadipocytes isolated from bovine intramuscular adipose tissue have a limited ability to accumulate lipid when compared to perirenal and subcutaneous preadipocytes. Because the glucocorticoid receptor is equally expressed in intramuscular, subcutaneous, and perirenal preadipocytes, and dexamethasone increased adipogenic enzymatic activity in equal proportions in these cell populations, the observed differences in adipogenic capacity among these cell populations appears to be unrelated to glucocorticoid receptor function. Experiments aiming to compare the expression of other proteins known to be involved in the regulation of preadipocyte differentiation may help decipher what is unique about intramuscular preadipocytes and facilitate the discovery of methods to selectively increase intramuscular lipid accretion in cattle.

Impacts
This work begins to illuminate the cellular mechanisms involved in fat development in cattle and inherent fat depot differences that exist. An enhanced understanding of fat development in cattle will ultimately lead to ways in which we can manipulate overall fat content and composition in beef. This will result in highly palatable and healthful beef products.

Publications

  • Grant, A.C. 2005. Differentiation of bovine intramuscular and subcutaneous preadipocytes. Ph.D. Dissertation, Michigan State Univ. E. Lansing.


Progress 01/01/04 to 12/31/04

Outputs
We hypothesized that adipogenic stimuli would enhance differentiation of bovine preadipocytes isolated from intramuscular (i.m.) and subcutaneous (s.c.) adipose tissues of an Angus steer, and the responses would be depot specific. The objectives of these experiments were to: 1) optimize differentiation using a clonally derived bovine preadipocyte line isolated from s.c. adipose tissue in serum free media; and 2) determine if a peroxisome proliferator-activated receptor agonist troglitazone preferentially induces differentiation of s.c. or i.m. clonally-derived preadipocytes. Preadipocytes isolated from the stromal-vascular cell fraction of i.m. and s.c. fat depots of an Angus steer (558 kg, 13.5 mo. old) were cloned using dilution or cloning ring techniques. A higher percentage of isolated s.c. clones (47.7%) were deemed adipogenic compared to i.m. (12.5%) (P < 0.001), as determined by oil red O staining. Experiments were conducted on an s.c. preadipocyte clone to test the adipogenic effects of insulin, bovine serum lipids, fatty acids, dexamethazone, and troglitazone when added to serum-free media. In objective 1, addition of 10 and 20 &#956;L/mL serum lipids to low glucose DMEM media containing 280 nM insulin increased glycerol-3-phosphate dehydrogenase activity (P < 0.01). Inclusion of 1.25 to 10 &#956;M troglitazone to media containing 280 nM insulin also increased in glycerol-3-phosphate dehydrogenase activity (P < 0.001). The combination of 280 nM insulin, 1 mM octanoate, and 10 mM acetic acid, with 48 h exposure to 0.25 &#956;M dexamethasone caused morphological differentiation in a small number of cells but did not stimulate glycerol-3-phosphate dehydrogenase activity (P = 1.0). When used together, 280 nM insulin, 20 &#956;L/mL serum lipids, 40 &#956;M troglitazone, and 0.25 &#956;M dexamethasone stimulated differentiation compared to the aforementioned treatment (P < 0.001). Omission of troglitazone or insulin from this media lowered glycerol-3-phosphate dehydrogenase activity by 68% (P < 0.001), while removal of dexamethasone tended to reduce activity (P = 0.06). In objective 2, s.c. (n = 3) and i.m. (n = 2) clones were used to determine the effects of 5 to 60 &#956;M troglitazone on differentiation when added to media containing 20 &#956;L/mL serum lipids and 280 nM insulin. Treatment with 20 to 60 &#956;M troglitazone enhanced differentiation compared to control (P < 0.02). No depot differences in response to troglitazone were detected (P = 0.47).

Impacts
These data demonstrate that clonally derived s.c. preadipocytes isolated from an Angus steer are capable of differentiation in response to combinations of insulin, fatty acids, serum lipids, dexamethasone, and troglitazone. In addition, no depot differences were observed between s.c. and i.m. preadipocytes in response to troglitazone. The use of clonally-derived preadipocytes coupled with the refinement of cell culture procedures and conditions will allow for direct depot comparison studies between bovine cells. This work provides the basis for investigations on the cellular mechanisms involved in bovine adipose tissue development, and inherent depot differences that exist. An enhanced understanding of adipose tissue development in the bovine will lead to the development of highly palatable and healthful beef products.

Publications

  • Grant, A. C., Ortiz-Colon, G., Doumit, M. E., and Buskirk, D. D. 2004. A procedure for the isolation, culture, and cloning of bovine preadipocytes. 2004 Midwestern Sec. Amer. Soc. Anim. Sci. March 15-17, 2004. Des Moines, IA.
  • Ortiz-Colon, G., Grant, A. C., Doumit, M. E., and Buskirk, D. D. 2004. Clonal efficiency and adipogenic capacity of preadipocytes isolated from bovine intramuscular, perirenal and subcutaneous adipose tissue. 2004 Midwestern Sec. Amer. Soc. Anim. Sci. March 15-17, 2004. Des Moines, IA.
  • Ortiz-Colon, G., Grant, A. C., Burton, J. L., Doumit, M. E., and Buskirk, D. D. 2004. Dexamethasone downregulates glucocorticoid receptor expression in cultured bovine preadipocytes. Amer. Soc. Anim. Sci. July 25-29, 2004. St. Louis, MO.


Progress 01/01/03 to 12/31/03

Outputs
Adipose tissue accretion is partially influenced by the proliferation and differentiation of adipocyte precursor cells (preadipocytes). However, little information on bovine preadipocyte culture methods exist. Our objective was to develop a procedure for the isolation, culture, and cloning of bovine preadipocytes. Adipose tissue from subcutaneous (s.c.), intramuscular (i.m.), and perirenal (p.r.) fat depots of an Angus steer (558 kg, 13.5 mo. old) were excised, trimmed of extraneous tissues, and minced into 2 mm sections within 20 min of exsanguination. Samples were then digested for 1 h in Dulbeccos modified Eagle medium (DMEM) containing 2 mg per mL collagenase and 2% BSA. Digesta were then filtered through 1000 uM, 500 uM, and 53 uM nylon mesh and centrifuged (10 min, 800 x g). Pelleted cells were resuspended in growth media (DMEM containing 10% fetal bovine serum (FBS)), and seeded on 35 mm-diameter dishes. Four days after seeding, cells were trypsinized and reseeded on 10 cm-diameter dishes at clonal densities (400 cells per dish). After 10 to 14 d, colonies were isolated using a cloning ring technique. Clones produced intracellular lipid droplets within 2 to 14 d when grown to confluence and induced to differentiate in serum free media, (DMEM, 20 mM glucose, 10 mM acetic acid, 50 ng per mL insulin), with 0.25 uM dexamethasone included for the first 48 h. When seeded at clonal densities and differentiated for at least 10 d, positive lipid staining with Oil Red O (ORO) was observed in at least 88% of colonies from each depot with i.m. (88%) similar to s.c. (95%), but less than p.r. (100%), (P < 0.05). Compared with serum free media, differentiation in the presence of 1% FBS tended to reduce the percentage of ORO-stained colonies (P = 0.08).

Impacts
Our results show that preadipocytes from bovine adipose tissues can be successfully isolated, cloned and cultured. This system will provide a useful tool for elucidating the cellular mechanisms responsible for differences in fat accumulation among economically important adipose depots.

Publications

  • Buskirk, D.D., A.J. Zanella, T.M. Harrigan, J.L. Van Lente, L.M. Gnagey, and M.J. Kaercher. 2003. Large round bale feeder design affects hay utilization and beef cow behavior. J. Anim. Sci. 81:109-115.
  • McCurdy, M.P. 2003. The effects of dexamethasone and sunflower oil on adipose tissue development in beef steers. M.S. Thesis, Michigan State Univ., E. Lansing.


Progress 01/01/02 to 12/31/02

Outputs
Adipose tissue development is an area that poses a challenge to the beef industry. Beef cuts with greater amounts of intramuscular (IM) fat or marbling have a higher probability of being juicy and flavorful, and of remaining tender when cooked by consumers. Subcutaneous (SQ) fat, however, has been shown to be less beneficial to the quality and palatability of beef and greater amounts of SQ fat result in greater trim waste from beef carcasses. Cattle often accumulate large amounts of SQ fat before IM fat develops. Due to the needs of the beef industry being in direct opposition of normal adipose tissue depot development, it is imperative that the molecular pathways that lead to development and terminal cellular differentiation of adipocytes be explored and that biological differences between adipose tissue depots be further characterized. The objective of this study was to identify unique aspects of IM and SQ adipose on a molecular level as well as to characterize a response to dexamethasone treatment within the two depots by surveying differences in expressed gene profiles. Four Angus steers (585 +/- 27 kg) of similar origin were assigned to two groups and received either a single injection of saline (CON) or of 0.1 mg dexamethasone/kg of body weight (DEX) 24 h before harvest. Tissue samples of SQ and IM adipose were obtained postmortem and immediately flash-frozen in liquid nitrogen for subsequent RNA isolations. Analysis of differential gene expression was carried out by using the isolated RNA to probe bovine cDNA microarrays. The presence of glucocorticoid receptor mRNA in each tissue was also examined using Northern blot hybridization. The microarray analysis revealed that DEX up-regulated (P < 0.01) expression of urokinase receptor mRNA in both adipose tissue depots, suggesting induction of the mitotic cell cycle and preadipose cell proliferation. In addition, IM adipose tissue from both treatment groups exhibited significantly greater expression of genes involved in cellular proliferation (MDM2; c-myc; hypoxanthine phosphoribosyltransferase; alpha-tubulin) than tissue collected from the SQ depot. Intramuscular adipose tissue was also observed to have greater expression (P < 0.05) of four genes involved in cellular apoptosis (Caspase-4, serine protease inhibitor p19, bax-alpha, and TRAF5) than in SQ tissue. Northern blot analysis confirmed expression of the glucocorticoid receptor (GR) in both types of adipose tissue; however, expression was significantly lower (P < 0.01) in IM than in SQ adipose depots. Administration of DEX lowered GR mRNA abundance in both adipose depots (P < 0.05), suggesting negative feedback of the steroid on expression of its receptor. The results of this study suggest that bovine SQ adipose tissue is different from IM adipose tissue at the level of expressed genes, and that SQ adipose depots may be more sensitive to the lipolytic effects of glucocorticoids due to greater abundance of GR than IM depots.

Impacts
The preliminary investigation points to fundamental differences between intramuscular and subcutaneous adipose on a molecular (gene expression) level. Differential gene expression in adipose tissue between depot location opens the possibility for independent manipulation of adipose tissue depots. Additionally, bovine adipose tissue expressed abundant glucocorticoid receptor-alpha, especially in subcutaneous adipose tissue. This suggests that glucocorticoids may provide a useful way to regulate differential fat accretion in specific adipose depots.

Publications

  • McCurdy, M. D. D. Buskirk, A. Grant, and J. Cowley. 2002. Influence of supplemental sunflower oil and dexamethasone therapy on performance and adipose tissue development in early weaned beef steers. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 581, Michigan State Univ., E. Lansing. Pp. 79-87.
  • McCurdy, M. P., D. D. Buskirk, A. C. Grant, and J. D. Cowley. 2002 Influence of supplemental sunflower oil and dexamethasone therapy on performance and adipose tissue development of early weaned beef steers. Amer. Soc. Anim. Sci. Midwest Sec. Mar. 18-20, Des Moines, IA p 72. (Abstr.).
  • Grant, A., D. D. Buskirk, S. R. Rust, and M. E. Doumit. 2002. Effect of growing and finishing implant strategy on overall performance and carcass characteristics of beef steers. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 581, Michigan State Univ., E. Lansing. Pp. 88-95.
  • Rust, S. R., J. R. Black, and D. D. Buskirk. 2002. Corn silage use in beef cattle growing and finishing diets: hybrid selection and economics. Amer. Soc. Anim. Sci. Midwest Sec. Mar. 18-20, Des Moines, IA p 67. (Abstr.).
  • Scheffler, J. M., D. D. Buskirk, S. R. Rust, J. D. Cowley, and M. E. Doumit. 2002. Effect of repeated administration of combination trenbolone acetate and estradiol implants on growth, carcass traits and beef quality of long-fed Holstein steers. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 581, Michigan State Univ., E. Lansing. Pp. 96-106.
  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, N. K. Ames, L. D. Bourquin, and S. R. Rust. 2002. Neutral detergent fiber concentration of corn silage and rumen inert bulk influences dry matter intake and ruminal digesta kinetics of growing steers. J. Anim. Sci. 80:833-840.
  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, R. J. Templeman, L. D. Bourquin, and S. R. Rust. 2002. Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of Angus and Holstein steers. J. Anim. Sci. 80:841-846.


Progress 01/01/01 to 12/31/01

Outputs
Within a carcass maturity classification, intramuscular fat (or marbling) is the major determinant of USDA quality grade. Beef cuts with greater amounts of intramuscular fat have a higher probability of being juicy and flavorful, especially when cooked well done by the consumer. Most management strategies designed to enhance marbling have been focused late in the feeding period even though intramuscular adipose cells appear in the bovine fetus. It is well established that glucocorticoids, or the glucocorticoid analog dexamethasone, enhances differentiation in nearly every preadipocyte line studied. There is limited evidence suggesting that exogenous glucocorticoid may increase intramuscular fat deposition in cattle when given from 30 to 90 days before harvest. Glucocorticoid effects appear to be mediated through increased metabolism of arachidonic acid. Arachidonic acid is found in only very low concentrations in common feedstuffs. However, an essential fatty acid, linoleic acid, is a precursor of arachidonic acid biosynthesis and has a high content in sunflower oil. Therefore, the objectives of this study were to determine the influence of sunflower oil supplementation and dexamethasone alone or in combination, on performance and adipose development in early weaned beef steers. Twenty-four early weaned steer calves were assigned to a 2 x 2 factorial arrangement of a control diet or a diet supplemented with sunflower oil and drug therapy treatments of physiological saline or dexamethasone every 28 d. Both dietary and drug treatments were continued for a period of 112 d. Following the 112 d treatment period, all steers were fed a common basal diet until harvest. Steers were measured by ultrasound every 28 d throughout the trial for ribeye area, 12th rib fat thickness, rump fat thickness, and percentage of intramuscular fat. Steer performance during the feeding period was also evaluated and complete carcass data was collected after harvest. Dexamethasone effectively lowered subcutaneous rib fat (P < 0.05), and subcutaneous rump fat (P < 0.01) over the trial period. Supplemental sunflower oil increased intramuscular fat over time (P < 0.01). Carcass marbling score and overall quality grade of treatment groups were not significantly different than control and there were no significant differences in average 12th rib fat of carcasses or final yield grade. Dexamethasone did not influence marbling or final quality grade of carcasses but decreased subcutaneous fat over time. Supplementation of sunflower oil increased marbling over the treatment period as measured by ultrasound but did not increase marbling scores of carcasses. In addition dexamethasone appeared to play a role in increasing feed efficiency, but efficiency was decreased when dexamethasone was administered in combination with sunflower oil.

Impacts
Beef intramuscular and subcutaneous adipose tissue may be subject to manipulation by glucocorticoids. Stimulation of intramuscular adipose tissue by dexamethasone may be able to increase marbling at a particular time/age or stage of tissue development. Additionally, dexamethasone may be a potentially useful tool in reducing subcutaneous adipose tissue, therefore producing more desirable beef products.

Publications

  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, and N. K. Ames. 2001. Neutral detergent fiber concentration of corn silage and rumen inert bulk influences dry matter intake and rumen digesta kinetics of growing steers. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 575, Michigan State Univ., East Lansing. pp. 60-72.
  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, and R. J. Templeman. 2001. Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of growing British and Holstein steers. J. Anim. Sci. 79(Suppl. 1):197 (Abstr.).
  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, and R. J. Templeman. 2001. Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of growing British and Holstein steers. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 575, Michigan State Univ., East Lansing. pp. 73-81.
  • Arseneau, J. D., L. L. Berger, D. D. Buskirk, D. B. Faulkner, F. L. Fluharty, R. P. Lemenager, S. C. Loerch, S. R. Rust, and M. N. Streeter. 2001. Feedlot performance and carcass traits of early weaned steers supplemented with either laidlomycin propionate or monensin. Amer. Soc. Anim. Sci. Midwest Sec. Mar. 19-21, Des Moines, IA p. 17. (Abstr.).
  • Barker-Neef, J. M., D. D. Buskirk, J. R. Black, M. E. Doumit, and S. R. Rust. 2001. Biological and economic performance of early-weaned Angus steers. J. Anim. Sci. 79:2762-2769.
  • Scheffler, J. M., D. D. Buskirk, S. R. Rust, J. D. Cowley, and M. E. Doumit. 2001. Repeated administration of implants to Holstein steers increases average daily gain, longissimus muscle area and the percentage of USDA Select carcasses. J. Anim. Sci. 79(Suppl. 1):275 (Abstr.).
  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, and N. K. Ames. 2001. Neutral detergent fiber concentration of corn silage and rumen inert bulk influences dry matter intake and ruminal digesta kinetics of growing steers. Amer. Soc. Anim. Sci. Midwest Sec. Mar. 19-21, Des Moines, IA p. 81. (Abstr.).


Progress 01/01/00 to 12/31/00

Outputs
Harvested feed is the single largest contributor to the cost associated with maintaining beef cows in Michigan. The Michigan Beef Cow Calf Survey revealed that 84% of winter forage was fed as hay and that most Michigan beef farms stored this hay as large round bales. Little has been done to characterize feeding losses of stored hay due to feeding method, yet some studies have identified that feeding losses may reach 20 to 30% of the dry matter fed. Many unique designs of large round bale feeders exist and sales claims have offered that "improved designs" reduce hay wastage. Although it is easy to hypothesize differences in wastage values based on the effects of feeder design on feed retention and animal behavior, insufficient research has been conducted to determine the magnitude of forage loss from these feeders. The objective of this study was to evaluate dry matter feeding loss of large round bale hay from feeders differing in design. One-hundred-sixty non-lactating, gestating beef cows (631 +/- 78 kg) were used to evaluate the quantity of hay loss from different designs of round bale (RB) hay feeders. Within two weight blocks, cows were equally allotted by body condition score (5.9 +/- .3) to one of four treatments in eight outside pens. Each pen was assigned to one RB feeder treatment 1) Ring, 2) Cone, 3) Cradle, or 4) Trailer, which was placed on concrete pads. Round bales (1.2 x 1.5 m) were stored inside and individually weighed prior to feeding. Cows were given ad libitum access to hay in the feeders for a 7-d period. Feeder treatments were rotated among pens and the trial was repeated for a second 7-d period. Hay that fell onto the concrete surrounding the feeders was collected daily, weighed, and sampled. Disappearance of hay was calculated as hay delivered to each pen, less residual hay in the feeder at the end of 7-days. Wastage of hay was calculated as the quantity of hay recovered from the perimeter of each feeder. Intake of hay was estimated as the difference between disappearance and wastage of hay. Mean wastage of hay was 8.9 percent of hay DM disappearance. Wastage of hay was 3.5, 6.1, 11.4, and 14.6 percent of hay DM disappearance for the Cone, Ring, Trailer, and Cradle feeders, respectively. Both round feeders (Cone and Ring) had less hay wastage than the Cradle or Trailer feeders (P < .05). There was a trend for less hay wastage from the Cone feeder compared to the Ring feeder (P = .08). The Cradle feeder had the greatest (P < .05) amount of hay wastage of the feeder designs tested. Estimated hay dry matter intakes, were similar (P > .20) among feeders and were within an expected range (1.8 to 2.0 percent of BW).

Impacts
Round bale hay dry matter loss under field conditions could easily be as high as 14%. Utilization will likely vary between feeder types, feeder design within type, forage type, bale size to feeder size ratio, bale density, frequency of feeding, number of cows per feeder, weather conditions, and other factors. This study demonstrated that dry matter waste was significantly different among the hay feeder designs tested. The best hay utilization was achieved when cows were fed in the cone and ring type feeders with hay savers.

Publications

  • Barker, J., D. D. Buskirk, M. E. Doumit, and S. R. Rust. 2000. Feedlot performance, carcass characteristics, and economic return of early weaned beef steers. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 569, Michigan State Univ., East Lansing. pp. 33-51.
  • Buskirk, D. D., and J. Barker. 2000. Performance of beef cows after early weaning calves. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 569, Michigan State Univ., East Lansing. pp. 8-13.
  • Buskirk, D. D., T. M. Harrigan, A. J. Zanella, and D. R. Hawkins. 2000. Large round bale feeder design affects wastage of hay. J. Anim. Sci. 78(Suppl. 2):93 (Abstr.).
  • Buskirk, D. D., J. VanLente, T. M. Harrigan, A. J. Zanella, D. R. Hawkins, M. Kaercher, and J. Cowley. 2000. Evaluation of hay loss from large round bale feeders. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 569, Michigan State Univ., East Lansing. pp. 2-7.
  • Cowley, J., D. D. Buskirk, G. Bednar, L. M. Cheney, D. L. Grooms, H. L. Person, and W. N. Osburn. 2000. 1999 Michigan beef industry priority survey. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 569, Michigan State Univ., East Lansing. pp. 101-108.
  • Cowley, J., D. D. Buskirk, and J. R. Black. 2000. MSU Integrated Resource Management Standardized Performance Analysis (MSU-IRM-SPA) for cow-calf operations: 1998 Summary. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 569, Michigan State Univ., East Lansing. pp. 14-21.
  • Korzun, L., D. D. Buskirk, T. M. Harrigan, D. R. Hawkins and A. J. Zanella. 2000. Large round bale feeder design affects occurrence of agonistic interactions in beef cows. J. Anim. Sci. 78(Suppl. 2):35 (Abstr.).
  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, N. K. Ames, L. D. Bourquin, and S. R. Rust. 2000. Brown midrib-3 corn silage improves digestion but not performance of growing beef steers. J. Anim. Sci. 78:2957-2965.
  • Tjardes, K., D. D. Buskirk, M. S. Allen, N. K. Ames, L. D. Bourquin, and S. R. Rust. 2000. Brown midrib-3 improves fiber digestibility of corn silage diets fed to growing beef steers. Beef Cattle, Sheep and Forage Systems Research and Demonstration Report, Research Report 569, Michigan State Univ., East Lansing. pp. 52-69.
  • Tjardes, K. E., D. D. Buskirk, M. S. Allen, N. K. Ames, L. D. Bourquin, and S. R. Rust. 2000. Brown midrib-3 improves fiber digestibility of corn silage diets fed to growing beef steers. J. Anim. Sci. 78(Suppl. 2):87 (Abstr.).


Progress 01/01/99 to 12/31/99

Outputs
Over two years, forty-five Angus-sired steer offspring of Angus and Angus crossbred females were used to determine the effects of early weaning on feedlot performance, carcass characteristics, and economic return to the cow-calf enterprise. Steers were assigned by birth date to one of two weaning treatments: 1) weaned at an average age of 100 d (EW), or 2) weaned at an average age of 200 d (NW). Within 36 d of weaning, steers were given ad libitum access to a high concentrate diet (90% dry, whole-shelled corn). Steers were harvested when 12th rib fat thickness averaged 1.27 cm within treatment as estimated by ultrasound. Carcass measurements were taken 48 h postmortem. In year 1, rib steak tenderness was determined at 14 d postmortem by Warner-Bratzler shear force and myofibril fragmentation index (MFI). The EW steers had greater ADG from time of early weaning to normal weaning than suckling NW steers (1.27 vs .86 kg/d, respectively; P < .001). However, EW steers tended to have lower ADG for the entire finishing period than NW steers (1.33 vs 1.39 kg/d, respectively; P = .08). When compared to NW steers, EW steers had lower daily dry matter intake (DMI; 7.40 vs 5.95 kg/d, respectively; P < .001) and lower total DMI for the finishing period (1618 vs 1537 kg, respectively; P = .04). The EW steers had better feed efficiency for the finishing period than NW steers (.223 vs .189, respectively; P < .001). Carcass weights were lighter for EW steers relative to NW steers (277.9 vs 311.2 kg, respectively; P < .001). There was no difference in yield grade (2.9 vs 3.0; P = .54) between treatments. All carcasses graded Low-Choice or greater and there was no difference in percentage of carcasses grading Mid-Choice or greater (94.5 vs 83.9% for EW and NW, respectively; P = .30). Warner-Bratzler shear force and MFI values were not different between treatments (P > .10). The EW steers had a lower cost of gain than NW steers (.905 vs 1.01 $/kg, respectively; P < .001), however due to lighter carcass weights, EW steers generated less return to the cow-calf enterprise than NW steers (358.56 vs 455.90 $/steer; P < .001). Early weaning steers at 100 d of age decreased total DMI, improved feed efficiency, and lowered cost of gain, however return to the cow-calf enterprise was decreased due to lighter carcass weights.

Impacts
Early weaning beef steers at 100 days of age resulted in lower daily and total feed dry matter consumption for the finishing period relative to normal weaning at 200 days of age. Early weaning improved feed efficiency and lowered cost of gain. However, EW steers had substantially lighter carcass weights than NW steers. This would result in less economic return (approximately $100/animal) to the cow-calf enterprise if ownership of calves of this biological type were retained through harvest.

Publications

  • Barker, J.M., D.D. Buskirk, H.D. Ritchie, S.R. Rust, R.H. Leep, and D.J. Barclay. 1999. Intensive grazing management of smooth bromegrass with or without alfalfa or birdsfoot trefoil: Heifer performance and sward characteristics. Prof. Anim. Sci. 15:130-135.
  • Barker, J.M., D.D. Buskirk, S.R. Rust, and M.E. Doumit. 1999 Feedlot performance and carcass characteristics of early weaned steers. J. Anim. Sci. 77(Suppl. 1):36 (Abstr.).
  • Tjardes, K.E., D.D. Buskirk, M.S. Allen, L.D. Bourquin, H.D. Ritchie, and S.R. Rust. 1999 Influence of feeding brown midrib corn silage during the growth phase on performance in feedlot steers. J. Anim. Sci. 77(Suppl. 1):83 (Abstr.).
  • Barker, J.M. 1999. The effect of early weaning beef calves on feedlot performance, carcass characteristics, cow performance, and economic return. M.S. Thesis. Michigan State University, East Lansing.


Progress 01/01/98 to 12/31/98

Outputs
One-hundred-eight mixed breed beef steers (initial weight, 557 lb.) were used to determine the effects of implant strategy on stocker and feedlot performance. Steers were allotted by weight and assigned to one of eighteen 4 acre pastures. Cattle in each pasture were randomly assigned to receive one of two treatments prior to moving to the pastures, no implant (Control), or implanted with Revalor-G; (trenbolone acetate, estradiol). Cattle began grazing pastures on May 11, 1998. Pastures consist of three forages; bromegrass-alfalfa (BR-ALF), bromegrass-birdsfoot trefoil (BR-BFT), or bromegrass + N fertilization (BR). All eighteen pastures were subdivided and grazed as four-paddock pastures. Due to a doughty spring and summer, one replication of steers were removed from pasture on July 24, 1998 (74 days), and feed free choice hay in dry-lot. The remaining replicates were removed on August 7, 1998 (88 days), when forage availability was deemed to be limiting animal performance. Steers were transported to the Beef Cattle Teaching and Research Center on the MSU campus, immediately following removal from pasture. Cattle were assigned to twelve pens with nine animals each. Each pasture implant treatment was subdivided, and steers were assigned to one of two feedlot implant treatments, either no implant (Control) or implanted with Revalor-S (trenbolone acetate, estradiol). Finishing phase implants were administered as cattle entered the feedlot. All steers are being fed a common corn-silage based diet, in which, percentage of concentrate was increased step-wise until steers were adapted to a finishing diet (80% corn, 15% corn silage, 5% supplement). Animal body weight gain was greater (P < .05), during the pasture phase, for cattle implanted with Revalor-G compared to control, 271 vs. 233 lb., respectively. There was no significant interaction between forage type and implant treatment. Animal body weight gain was greater (P < .05) for cattle grazing grass-legume mixed pastures (BR-BFT = 263 lb. and BR-ALF = 259 lb.) than for grass only pastures (BR = 235 lb.). Preliminary data from performance of cattle in the feedlot suggests that there is not a significant carry-over effect of pasture forage type or implant treatment on finishing phase body weight gain.

Impacts
(N/A)

Publications

  • Barker, J. M., D. D. Buskirk, H. D. Ritchie, S. R. Rust, R. H. Leep, and D. J. Barclay. 1998. Heifer performance and forage characteristics of smooth bromegrass (BR), birdsfoot trefoil-BR, and alfalfa-BR rotationally grazed pastures. Research Report 559, MSU. pp. 21-28.
  • Buskirk, D. D., D. L. Grooms, K. S. Gould, J. R. Molesworth, and J. D. Cowley. 1998. Effectiveness of the Ivomec SR bolus in promoting weight gain of grazing steers in Michigan. Research Report 559, MSU. pp. 29-32.


Progress 01/01/97 to 12/31/97

Outputs
In the forth year of a long-term grazing study, 108 mixed breed beef steers were allotted to eighteen 4-A pastures (6 steers per pasture). There were three forage treatments: bromegrass (BR), alfalfa-bromegrass (ALF-BR) and birdsfoot trefoil- bromegrass (BFT-BR). Within each forage treatment, there were two grazing systems: 4-paddock conventional rotation (CONV) and 12-paddock intensive rotation (INT). Each of the six treatments was replicated three times. All steers grazed for 129 days, Steer average daily weight gain ranged from a low of 2.3 lb. for BR/INT to a high of 2.7 lb. for BFT-BR/INT. However, there were no significant differences in average daily gain or gain per acre due to the treatment main effects in 1997. Clipped pasture samples were collected to determine sward quality and specie changes over time. These data will be summarized along with the previous years to determine the effect of species and grazing management systems on pasture productivity and animal performance over various environmental conditions.

Impacts
(N/A)

Publications

  • No publications reported this period