2003: Summaries of beef cattle research from Montana State University

Research and Education Nitrate Concentration of Cereal Forage Species at Three Stages of Maturity

Surber, S. D. Cash, J.G.P. Bowman, and M.C. Meuchel

ABSTRACT: Cereal forages have become an increasingly economical source of winter feed for livestock producers, comprising 11% of all hay harvested in Montana. Livestock producers need to be concerned with nitrate concentrations when feeding annual cereal forages. Six cereal forage species (18 varieties) were grown in a field trial under irrigated conditions in Bozeman, MT, and were used to test the effects of cereal forage species and stage of maturity on forage nitrate concentration. Forage clip samples were collected at three stages of plant maturity: boot, anthesis and when the plots were harvested for hay (milk stage of maturity). Samples were ground and evaluated for DM and nitrate-nitrogen (NO3-N). The range in NO 3-N was from 0.01 to 0.55%. There were significant (P < 0.05) cereal forage species, stage of maturity and species x maturity interaction effects on NO 3-N concentration. Nitrate-nitrogen concentration at the boot stage of maturity did not differ (P > 0.05) when compared to the anthesis stage of maturity (avg. 0.244 %). However, NO 3-N concentration at harvest was 36% lower than at anthesis (0.168 vs. 0.230 %). Barley forage NO3-N was similar (P > 0.05) when compared to emmer, triticale and wheat x spelt crosses (avg. 0.195%) and lower (P < 0.001) when compared to oats and spelt forage (0.186 vs. 0.341 and 0.258%, respectively). Barley forage NO 3-N concentration was highest (P < 0.05) at the boot stage, intermediate at anthesis and lowest at harvest (0.230, 0.195 and 0.131%, respectively). Oat forage maintained high NO 3-N concentrations at all growth stages (P > 0.05; avg. 0.341%).

It appears that stage of maturity and cereal forage species greatly affect NO 3-N concentration. Also, NO 3-N concentrations of various cereal forage species respond differently at boot, anthesis and harvest. This implies that different harvest management must be implemented for oats when compared to other cereal forage species.

Effects of Barley or Corn on Performance and Digestibility in Finishing Diets

J. J. Kincheloe, J.G.P. Bowman, L.M.M. Surber, D. L. Boss, M. F. McDonnell, K. A. Anderson, and T. K. Blake

ABSTRACT: Barley is an important feed grain throughout Canada and the Pacific Northwest, while corn is the predominant grain source in finishing diets throughout the United States. Limited comparisons are available evaluating differences between the feed value of corn and barley. Eighty steers (avg initial wt 758 lb) were fed finishing diets for 112 days to determine the effects of corn and three barley varieties (H3, Harrington, and Valier) on feedlot performance, nutrient digestion, carcass characteristics, and grain energy content. Grains were dry-rolled, and diets formulated to contain 15% CP, 0.92 Mcal/lb NEm and 0. Mcal/lb NEg. Steers were allotted by weight to 16 pens completely randomized design with pen as the experimental unit. Steers were weighed every 28 days and diet, ort, and fecal samples were collected, composited by pen, and analyzed for nutrient content. Steers were harvested when 70% were visually estimated to grade Choice. There were differences (P > 0.10) among diets for ADG (avg 3.48 feed efficiency (avg 16.3 lb gain/100 lb feed), 21.2 lb), or starch digestibility (avg 97%). Fat thickness greatest (P = 0.03) for steers fed corn (avg 0.47 in), and for steers fed H3 and Valier (avg 0.37 in). Steers fed higher (P =0.07) yield grades than steers fed barley (avg vs 2.8, respectively); however, there were no differences (P > 0.10) detected for any other carcass characteristic. Barley had similar (P > 0.10) NEm and NEg values as compared corn (avg 0.99 and 0.69 Mcal/lb, respectively).

Lack of differences in animal performance and grain energy values suggest that barley has equal feeding value to corn in finishing diets, and that the underestimate net energy values for barley.

Effects of Barley Processing, and Test Weight on Feedlot Performance and Carcass Characteristics of Finishing Beef Steers

M.F. McDonnell, J.G.P. Bowman, L.M.M. Surber, J. J. Kincheloe, M.A. Thompson, K.A. Anderson, and T. K. Blake.

ABSTRACT: Eighty crossbreed beef steers weighing 849 lb were fed a finishing diet (83% barley, 6% chopped straw, 3% oil and 8% supplement) in a study examining the effects of barley processing (whole vs. cracked), and test weight (heavy vs. light; 49 lb/bu and 39 lb/bu, respectively) on animal performance and carcass characteristics. A processing and test weight interaction (P < 0.01) was detected for final weight, ADG, intake, and feed efficiency. Final weight was highest (P = 0.005) for steers fed cracked heavy barley and cracked light barley (avg. 1263 lb), intermediate steers fed whole light barley (1113 lb) and least for steers fed whole heavy barley (1032 lb). Average daily gain was highest (P = 0.001) for steers fed cracked heavy and cracked light barley (avg. 3.64 lb/d), intermediate for steers fed whole light barley (2.34 lb/d), and least for steers fed whole heavy barley (1.65 lb/d). Dry matter intake was greatest (P = 0.01) for steers fed cracked heavy barley and cracked light barley (avg. 25.6 lb/d), intermediate for steers fed whole light barley (21.4 lb/d), and least for steers fed whole heavy barley (17.9 lb/d). Feed efficiency (gain/100 units of feed) was highest (P = 0.002) for steers fed cracked heavy barley (14.7), followed by cracked light barley (13.9), whole light barley (9.7), and whole heavy barley (8.1). Cracked barley had higher (P = 0.001) NEm and NEg values than whole barley (avg. 0.93 vs. 0.77 Mcal/lb for NEm; avg. 0.64 vs. 0.49 Mcal/lb NEg). No effect (P = 0.40) of barley test weight was seen on NEm or NEg values. No differences (P > 0.08) in carcass characteristics were detected for barley test weight or processing. In summary, barleys with test weights of 49 and 39 lb/bu had energy similar contents, while NEm and NEg for cracked barley were 22 and 30% higher, respectively, than for whole barley fed to finishing steers.

Effects of Processing and Test Weight of Barley When Fed to Backgrounding Calves

D.L. Boss, J.G.P. Bowman, L.M.M. Surber, D.G. Sattoriva and T.K. Blake

ABSTRACT: A study was initiated to evaluate the effects of light or heavy test weight barley fed whole or dry rolled to calves on a backgrounding diet. Eighty commercial Angus steers were allotted to 16 pens on an equal pen weight basis with treatment being randomly assigned to pen. A 2 x 2 factorial arrangement was used to test the effects of barley test weight (light; 39 lb/bu vs. heavy; 48 lb/bu), processing (whole vs. dry rolled) and their interaction. Steers had ad libitum access to feed and water throughout the 56-day trial. The diets were balanced to meet or exceed all NRC requirements and to provide 0.65 Mcal/lb NEm and 0.39 Mcal/lb NEg, enabling a 750 lb steer to gain 2 lb/d. Diets were offered once daily at 0800 and consisted of 49.0% Pubescent wheat grass (chopped to pass a 3 inch screen), 45.0% barley ('Morex') and 5.7% commercial backgrounding pellet on DM basis. Water was used as a diet conditioner. Data analyzed using GLM procedure of SAS. No interactions were detected (P > 0.10). Dry matter intakes were notent (P = 0.51, avg 19.6 lb/d) for the 56-d trial. There difference (P > 0.05) in final weights or ADG when lb, 2.4 lb/d) or heavy (842 lb, 2.4 lb/d) test weight was evaluated. Feeding dry rolled barley resulted in final weights (P = 0.06; 853 vs 826 lb) and increased = 0.001; 2.6 vs 2.2 lb/d) when compared to whole steers. Barley test weight did not affect steer performance in trial. However, processing the barley (dry rolling) before feeding it to steers in a backgrounding diet increased performance by 17% when compared to feeding the barley whole.

Effect of Barley Varieties Harvested for on Backgrounding Steer Performance and Diet Digestibility

A. L. Todd, J.G.P. Bowman, L.M.M. Surber, M. A. Thompson, Kincheloe M. F. McDonnell, and P. F. Hensleigh.

ABSTRACT: Barley harvested as hay is a significant source of winter forage for livestock producers in Limited data is available using hay barley as a roughage source for backgrounding steers. Ninety-six Angus cross steers were allotted to 16 pens in a randomized complete block design. The objectives of this study were to 1)mine the effects of four barley varieties on animalmance and diet digestibility, and 2) determine the effects of feeding awned vs. hooded head type barley. MT Westford, and Haybet are all hooded forage barley while Valier is an awned feed barley variety. Steers wereen ad libitum access to their roughage source, 5.7 d of cracked feed barley, and 1 lb/head/d of a 32% CP supplement. All roughage was chopped to 2 Pen was the experimental unit in the 60-day trial. Steers were weighed and diet, and fecal samples were obtained on day 28 and upon completion (day 60) of the trial. and fecal samples were composited by pen and analyzed for nutrient content. Steers fed MT981060 and Valier 55% greater (P < 0.01) ADG when compared to steers Haybet and Westford barley (avg 3.29 vs. 2.75 lb/d,tively). Dry matter intake was greatest (P < 0.01) for fed MT 981060 and Valier, intermediate for Haybet and for Westford (avg 22.2 vs. 21.2 and 17.8 lb/d, respectively) Steers fed MT 981060, Valier, and Westford barley had improvement (P < 0.01) in feed efficiency when to steers fed Haybet barley (avg 15.07 vs. 12.9 lb feed, respectively). Feeding an awned variety did not impact intake, ADG, feed efficiency. MT 981060 had superior feeding for backgrounding steers and is scheduled for release the Montana Agricultural Experiment Station.

Effect of Exogenous Progesterone Before Calf Removal and Prostaglandin F2ðÀ on Estrous Response And Pregnancy Rates In 3-Year-Old Beef Cows

J.L. Olson, A.J. Roberts, J.A. Paterson, and R.N. Funston

ABSTRACT: Objectives for this experiment were to determine effects of a 7 d pretreatment with an intravaginal progesterone insert (CIDR) on estrous response and pregnancy rates in 3-year-old postpartum beef cows synchronized with calf removal and prostaglandin F2ðÀ. Cows (BW = 1074 �} 16.3 kg; body condition score = 3.8 �} .07; days postpartum = 58.7 �} 1.2 d) were randomly allotted to either Control (n = 22; i.m. injection of 25 mg PGF2ðÀ [Lutalyse] on d 0) or CIDR treatment from 7 to 0 d preceding, PGF2ðÀ injection on d 0 (n = 18). All calves were weaned on d 0. Cows were observed for estrus for 120 h after PGF2ðÀ and inseminated by AI approximately 12 h after the onset of estrus. A bull was placed with cows 12 d after PGF2ðÀ and removed 40 d after PGF2ðÀ. Circulating progesterone concentrations were determined in blood samples collected on d 7, 0, and 18. Pregnancy status was diagnosed by ultrasonography on d 54 and 145 after PGF2ðÀ. Synchronization rates were higher (P < 0.05) for CIDR (100%) compared to Control (77%) cows. Time of estrus did not differ (P > 0.10) between Control and CIDR cows (2.41 �} .15 d). Pregnancy rates by AI were not different (P = .28), between Control (18%) and CIDR (33%) cows. Overall pregnancy rates were higher (P < 0.10) in Control (97%) compared to CIDR (80%) cows. Concentrations of progesterone on d 7, 0, and 18 did not influence (P > 0.10) overall pregnancy rates; however, progesterone concentrations were increased (P < 0.05) in CIDR cows on d 0 (5.6 vs. 2.9 ng/mL, for CIDR vs. Control) and d 18 (7.1 vs. 4.8 ng/mL, for CIDR vs. Control). Administration of a CIDR 7 d before calf removal and PGF2ðÀ increased concentrations of progesterone on d 0 and 18, and increased the proportion of cows exhibiting estrus. However, CIDR treatment did not improve conception and AI pregnancy rates and reduced overall pregnancy rates.

The Effects of Cattle Gender on Feedlot Performance, Carcass Characteristics and Muscle Tenderness

Travis Choat, J. A. Paterson, B. M. Rainey, M. C. King, R. J. Lipsey, K. E. Belk and G. C. Smith

ABSTRACT: The effects of gender on rate of gain, carcass traits, shear force and trained sensory panel ratings of beef palatability were evaluated using 202 progeny of Angus or Simmental sires. Steers (n=99), heifers (n=57) and intravaginally spayed heifers (n=46) were fed a high energy diet for 161d. No implants were administered and heifers were not fed melengestrol acetate to suppress estrus. Steers had faster (P < 0.01) daily gains than heifers. The heavier (P < 0.01) final live weights of steers resulted in 55 lb heavier (P < 0.01) hot carcass weights at similar (P = 0.86) levels of fat thickness compared with heifers. Spayed heifers had a 5.7% smaller longissimus muscle area (P < 0.05) compared with steers and intact heifers, which were similar. Calculated yield grades were similar (P = 0.21) among treatments, and USDA Quality grades and marbling scores were lower (P < 0.01) for steers compared to heifers. In order to examine gender effects on tenderness, shear force and sensory panel data were analyzed using an ANOVA model marbling score as a covariate. Shear force values after 7 and 14 d of aging were lower (P < 0.01) for steers to heifers which were not different between tratements. Mean shear force values at 7 and 14 d of aging were 7 7.3 lb (steers) 8.4 and 7.9 lb (intact heifers) and 7.9 and lb (spayed heifers), respectively. After 21 d of aging, shear force did not differ (P = 0.11) among genders. A trained sensory panel evaluated steaks (aged 14 d postmortem) from 193 of the cattle for juiciness, muscle fiber connective tissue amount and overall tenderness using an 8-point structured rating scale. Steaks from steers received more favorable ratings (P < 0.01) for muscle fiberness, connective tissue amount and overall tenderness at similar levels of marbling compared with spayed and intact heifers. Under the genetic and environmental conditions of this experiment, steers had faster daily gains and produced heavier carcasses at similar levels of subcutaneous fat, compared to heifers. Intact and spayed heifers produced strip loin steaks that had higher average shear force values (i.e., were less tender) and lower average ratings for sensory panel tenderness than were those from steers.

Effect of Age, Gender and Grain Processing Method on Rate and Efficiency of Gain Diet Digestibility by Beef Cattle

B.M. Rainey, J.A. Paterson, M.C. King, L.W. Barney, W.T. Choat

ABSTRACT: The objectives of these experiments were to determine the effects of animal age (cows vs. calves), animal gender (steers vs. heifers) and barley processing method (whole vs. rolled) on rate and efficiency of gain and diet digestibility when barley was fed as a supplement to medium quality grass hay (12.3% CP; 37.7%ADF, DM basis). Also evaluated was a control treatment in which animals were not supplemented with barley. Forty, 36 mo old, Angus cows (1085 �} 108 lb), 21 heifer calves (98 �} 8 d of age; 235 �} 33 lb), and 19 steer calves (99 �} 7 d of age; 266 �} 35 lb) were allotted to treatments in a 2 x 2 x 2 + 1 arrangement. All cattle were blocked by age and sex and fed for 65 d with pen as the experimental unit. Light test weight barley (46 lb�Ebu-1) was supplemented at 0.5% BW (5.3 lb�Ecow-1�Ed-1 and 1.32 lb�Ecalf-1�Ed-1, DM basis). Grass hay was offered to cows at 21.4 lb�Ehd-1�Ed-1 and to calves at 6.2 lb�Ehd-1�Ed-1 (DM basis). Rations were formulated to be isonitrogenous using a 31.6% CP supplement and cows received 1.0 lb�Ehd- 1�Ed-1, while calves received 0.50 lb�Ehd-1�Ed-1. Individual full weights were taken on two consecutive days at the beginning and end of the study. Data were analyzed as a factorial for the main effects of animal age, gender, barley processing method and the processing x age interaction. No interactions were measured in this study. Animals fed the control diet had similar (P > 0.05) rates and efficiencies of gain as supplemented animals. Barley processing had no effect (P > 0.05) on rate or efficiency of gain for cows or calves. However, cows gained (P < 0.05) weight faster than calves, consumed more (P < 0.05) DM but were less efficient (12.6) than calves (avg. 7.6). A digestion study was conducted using animals from Exp 1. The protocol and dietary treatments remained the same with the exception that animal was the experimental unit. Differences (P < 0.01) were observed for DMI between age groups. There were no differences in digestibility of OM, N, ADF, NDF, or starch between cows vs. calves and whole vs. rolled barley supplements. As expected g of starch disappearance were greater for the supplemented diets vs. unsupplemented treatment. Results suggest that improved performance and digestibility were not measured when the barley was rolled. Also, gains were more efficient for calves than cows.

Evaluation of Drought Management Strategies for Cow-Calf Enterprises

R.E. Kruse, M.W. Tess, R.K. Heitschmidt, J.A. Paterson, and B.F. Sowell

ABSTRACT: The objective was to evaluate alternative drought management strategies for their effects on profitability based on early detection of drought. A bio-economic model was parameterized to represent a range-based cow- calf production system in the Northern Great Plains. The base management system was characterized by inputs required to maintain herd size of 511 cows during an average climatic year with a fixed forage base of 4,329 AUM of range forage, plus 629 ton grass and 208 ton alfalfa hay. Treatments were factorially arranged where management (early vs normal) and intensity of drought (moderate, 20% reduction in available forage vs severe, 40% reduction in available forage) were evaluated for effects on system performance The early management (EM) scenario included detecting drought by July 15 and decreasing the average age ating to 90d. The normal management (NM) scenarioed no 'early' management changes to emerging drought, but nutritional management was modified as needed maintain in animal performance. A second bio-economic computer model was used to simulate drylot performance for early-weaned calves. Outputs from the two models were combined and treatments were evaluated based on feed costs, average weaning weight, ranch gross margin (gross margin variable costs, RGM), and cumulative margin (ranch gross margin + revenue from drylot calves, CGM). During average climatic conditions CGM under base management system was $137,730. During drought CGM was reduced compared to the base system: EM and 48.8%) and NM (33.6 and 72.3%) for moderate and severe drought, respectively. For both levels of drought, had lower purchased feed costs and higher CGM than Directly feeding EM calves proved more efficient thaning NM cows to produce milk to maintain calf Early weaning should effectively reduce the negative effects of drought on gross margin.

Effects of Flunixin Meglumine on Embryonic Loss in Stressed Beef Cows

M. L. Merrill, R.P. Ansotegui, N.E. Wamsley, P.D. Burns, and Geary.

ABSTRACT: The objective of this study was to determine if flunixin meglumine reduces early embryonic in cows subjected to stress. Approximately 14 d following synchronization of estrus and artificial insemination 97 cows were assigned to one of three treatments by AI date, and AI technician. Treatments were control induced stress (S), and induced stress with flunixinmine (1.1mg/kg, i.m; SFM). Rectal temperatures were recorded and blood samples collected (caudal venipuncture) for measurement of cortisol, and PGF metabolite (PGFM) concentrations before and after induced stress. Control cows remained at the ranch with their calves and had access to water but not feed, while S and SFM cows loaded on semi-trucks and transported for 4 h (meanent temperature 75 o F). Cows were not exposed to clean- bulls until after treatment. Transrectal ultrasonography used to determine AI pregnancy status 55 to 57 d post Pregnancy rates to AI tended (P = 0.17) to be higher SFM cows (84%) than S cows (69%) while AI pregnancy of CON cows was intermediate (76%). Cortisol concentrations before and after treatment were 21 and 24 ng/ml, and 17 ng/ml, and 18 and 8 ng/ml, for CON, S, and cows, respectively. Change in cortisol concentration was different (P < 0.06) between CON and S or SFM, but versus SFM (P > 0.10). No changes (P > 0.10) in PGFM detected among the three groups between the sampling periods. Body temperature decreased between the sampling periods for all treatments, but the change in- ture was greater (P < 0.03) for S and SFM cows CON. Across treatments, change in cortisol concentration between sampling periods did not influence (P > 0.10) AI pregnancy status, however, PGFM increased (P<0.09) 24.72 pg/ml or decreased 5.19 pg/ml in cows diagnosed open or AI pregnant. In summary, flunixin meglumine appears to decrease the stress-induced embryonic loss, but the role of PGF and cortisol remain unclear.

Using Prescribed Burning to Rejuvenate Prairie Riparian Ecosystems: Preliminary Results

Clayton B. Marlow

ABSTRACT: Efforts to reverse the downward trend in riparian function on a BLM grazing allotment in central Montana have been stymied by inadequate water supplies. Additional sources for water development are lacking because of a combination of drought and extensive conifer invasion within the allotment. However, the presence of riparian communities in large draws away from the main stream channel indicated that water had been more widely distributed in past decades. Range ecology literature suggests that conifer encroachment may be exaggerating drought effects and that removal of all or part of the conifers would reduce the draw-down of shallow ground water levels. Higher groundwater levels would either allow springs to flow again or facilitate low-cost well development. Approximately 1,000 acres of conifer woodland was burned in the spring of 2002. Initial results from ground water monitoring indicate that water levels in burned areas increased more than in unburned areas following rain and snowfall in late May and early June 2002. If this pattern continues, there should be more opportunity to disperse livestock grazing across the allotment and reduce grazing pressure on riparian areas.

A Systems Approach to Reducing Morbidity in Feeder Calves

D. J. Fennewald, J. A. Paterson, R. J. Lipsey, and R. N. Funston

ABSTRACT: A group of 1,836 calves from eight ranches were individually identified to determine if a standardized weaning protocol which included vaccinations, nutrition and 45-d of backgrounding could reduce morbidity (sickness) from weaning until shipment into the feedlots. Freshly weaned calves were randomly allocated to two treatments: 1) Present Ranch Management (PRM) which was defined as present weaning practices or 2) MSU Protocol (MSU) in which calves were fed either 4.0 lbs/day of a weaning pellet or 1 lb/day of liquid supplement for 28 d. The supplement contained additional levels of Cu, Zn, Mn, CP, vitamins A, D and E and a coccidiostat. All ranches divided calves into PRM and MSU groups (779 and 1057 animals, respectfully) and group size ranged from 26 to 188 animals. Overall morbidity was 2.7% for calves on the MSU protocol compared to 4.5% for calves on the PRM protocol (P < .05). The range in morbidity was 0 to 9.8% for calves on MSU vs. 0 to 24.7% for calves on PRM. During the first 28 d after weaning, ADG was not different (P = .14) between treatments. However, ADG was greater (P < .05) for MSU from 0-45 d compared with PRM (2.46 vs. 2.29 lbs/day). Calves exhibiting morbidity had 19% slower (P < .05) ADG compared to healthy calves (1.96 vs. 2.42 lbs/day). These results suggest that calves which followed a protocol of defined vaccinations, nutrition and backgrounding performed better than control calves.

Calving Ease of Heifers Bred to Angus and Simmental Sires Selected for Decreased Dystocia

H.C. Van Wagoner, R.P. Ansotegui, M.D. Ropp, and R.J. Lipsey

ABSTRACT: The objective of this study was to compare birth weight, gestation length, and percent assisted births of calving ease Simmental and low birth weight Angus Angus yearling heifers were bred in two consecutive years (1999 and 2000) at four locations by AI using semen collected from Simmental (n = 20) and Angus (n = 27) Birth weights, gestation lengths, and calving ease scores = unassisted, 2 to 4 = various levels of assistance) of calvings in 2000 and 2001 were analyzed to determine breed effect. Calving ease scores were recorded so that percentage of assisted births could be calculated. The statistical model included the fixed effects of year of breed, calf sex, ranch, two-way, and three-way interaction. Sire breed affected (P < 0.01) birth weight, gestation and percent assisted. Simmental sired calves were 4.7 lbs heavier at birth, 2.90 �} 0.48 days longer in gestation and assisted 1.44 more times than Angus sired calves. sex affected (P < 0.01) birth weight and gestation length. Bull calves were 6.1 lbs heavier at birth and 1.30 �} 0.27 longer in gestation length than heifer calves. Furthermore, bull calves were assisted 2.51 and 1.36 times more than heifer calves, 2000 and 2001, respectively. In this study, calf sex was the leading cause of dystocia, followed by sire breed.

Effect of Supplemental Trace Mineral Level and Form on Peripubertal Bulls

W.L. Alexander, R.P. Ansotegui, D.S. Spickard, C.K. Swenson, E.E Grings and T.W. Geary

ABSTRACT: Adequate dietary trace minerals are an essential component to growth and sexual development in males. Our objectives were to determine if different supplemental trace mineral levels and/or forms (sulfate and amino acid complexes) influence age at puberty, semen quality and scrotal circumference. Forty-three crossbred, prepubertal bulls were blocked by age (258 d �} 8.9) and scrotal circumference into five different treatment groups: 1) 1x sulfate form (1S); 2) 1x complexed form (1C); 3) + 1C (2SC); 4) 1S + 2x1C (3SCC); and 5) 3x1S (3S). supplementation level contained 360 mg Zn, 125 mg Cu, 200 mg Mn and 12.5 mg Co. Bulls were assigned to gate pens with one animal/treatment/pen. Supplements were individually fed daily in 0.45 kg of wheat middlings from day 0 to 100. The basal diet of 7% alfalfa hay, 10 corn, 75.5% corn silage and 7% protein supplement was to all bulls and was formulated to achieve 1.2 kg ADG. Liver biopsies were collected on days -21 and 100, and were analyzed for Zn and Cu concentrations. Scrotal circumference, semen, and blood samples were collected on days -14, 14, 42, 70, and 98. Semen was collected by electroejaculation and spermatozoa evaluated for morphology and motility. Puberty was defined as the age at which an ejaculate contained a minimum of 50 x 106 total spermatozoa with at least 10% progressive motility. All bulls were deficient in Cu yet adequate in Zn on day 21 according to liver concentration. Following 100 d on treatment, liver Zn concentrations decreased (P < 0.01) and liver Cu concentrations increased (P < 0.01) in bulls regardless of treatment. Day 100 liver Zn concentrations were similar (P = 0.59) across treatments, but there was a tendency for liver Cu concentrations to be greater (P = 0.07) in 3SCC and 3S bulls compared to 1C and 1S bulls, whereas 2SC bulls were intermediate. Scrotal circumference did not differ (P > 0.10) among treatments throughout the trial. Two bulls did not reach puberty and were removed from the puberty data. On day 42, more (P = 0.03) bulls fed complexed trace minerals (1C, 2SC, 3SCC; 79%) were pubertal compared to those fed only sulfate trace mineral (1S, 3S; 47%). Bulls fed complexed supplement tended to reach puberty after fewer (P = 0.11) days on treatment (43.9 �} 5.7 d) than bulls fed only sulfate supplement (58.5 �} 6.7 d). Bulls fed 3SCC tended (P = 0.07) to reach puberty at a younger age (315.2 �} 7.9 d) than bulls fed 3S (336.8 �} 7.9 d). On day 42, 3S bulls had a larger (P = 0.08; 39.2%) percentage of proximal and distal droplets in ejaculates compared to all other treatments (1S, 1C 2SC, 3SCC; 15%, 20%, 25%, 21.6% respectively). Based on decreased final liver Zn concentrations regardless of treatments, we conclude that NRC recommendations for Zn may be inadequate for bulls during the peripubertal stage of development. Supplementing Cu and Zn deficient prepubertal bulls a complexed form of trace minerals may lower the age at puberty. However, no apparent differences (P > 0.41) in semen characteristics existed at one year of age.

Effects of corn and barley based diets on meat characteristics

C.J. Bergner, J.A. Boles, J.G.P. Bowman, D.L. Boss, T K. Groenlund

ABSTRACT: Steers (n=160) were fed isocaloric finishing diets on one of three barley varieties (Chinook, Logan or H3 newly released barley variety) or corn (40 steers/treatment) at two feedlots in Montana. Steers were assigned to in the feedlot by weight so that pen weights were Steers were harvested when visual inspection of animals determined that 75% of the carcasses would grade Steers were harvested at a commercial packing plant, standard industry practices. Carcass measurements, car - cass weight, fat thickness, ribeye area, internal fat and marbling scores were obtained from each carcass. ribs (IMPS 103) were removed from 72 carcasses, vacuum packaged and transported under refrigeration to Montana State University (MSU) for analysis. Three consecutive steaks (1.25 inch) were removed from each rib and determine color stability, tenderness, proximate analysis and pH. The study was a completely randomized design with animal as the experimental unit. There were no treatment interactions detected (P>0.05). Diets fed to had no effect (P>0.05) on the quality and yield grade carcasses nor on tenderness of beef steaks from the - casses. Diet fed to steers had no effect (P>0.05) on the color of beef steaks, however steaks from steers fed based on Logan barley had a more rapid decline (P=0. in Hunter a* values (redness) during storage than did from steers fed corn or other barley varieties. Greater color stability results in a longer shelf-life hence different diets fed to cattle can contribute to variability of color in the retail case and thus affect retail shelf Further research is necessary to determine the cause the color differences.

Beef: Questions & Answers is a joint project between MSU Extension and the Montana Beef Council. This column informs producers about current consumer education, promotion and research projects funded through the $1 per head checkoff. For more information, contact the Montana Beef Council at (406) 442-5111 or at beefcncl@mt.net

 

Return to regular view	Text-only	Updated: 08/29/2006