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To assess incidence of elevated body temperature expressed by stocker cattle marketed in central Kentucky at different times of the year, rectal body temperature data were collected during a 9-mo period on 11,084 stocker cattle varying in genetic type, sex, weight, and hair-shedding condition. If rectal body temperature was > 39.4 °C, body temperature was considered to be elevated and recorded as 1; otherwise, 0 was recorded. Incidence (0,1) of elevated body temperature data were analyzed assuming a mathematical model that included effects for calf genetic type [Britishsired (BS), Continental-sired (CS), Holstein-sired (HS)], sex [bull (B), steer (S), heifer (H)], month, week/month, hair shedding condition [slick-shed (SS), partial-shed (PS), nonshed (NS), average weight of group [136 to 181, 182 to 226, 227 to 271, 272 to 317 kg] and appropriate two-way interactions between these effects. Specific comparisons involving calf genetic type, sex, and hair-shedding condition indicated that incidence of elevated body temperature was: 1) similar for HS and (BS + CS)/2 cattle; 2) 5.2% greater (P < .01) for BS than for CS cattle; 3) 12.1% less (P < .01) for SS than for (PS + NS)/2 cattle; 4) 12.3% less (P < .01) for PS than for NS cattle; 5) similar for Hand (B + S)/2 cattle and; 6) 10.9% higher (P < .01) for B than for S cattle. Also, incidence of elevated body temperature differed depending upon weight and month when cattle were marketed.

Observations on hoof growth of Angus (n = 20), Brangus (n = 19), Hereford (n = 31), and Simmental (n = 53) during a 112-d postweaning feedlot performance test were used to study hoof characteristics relative to hoof mineral composition. Hoof measurements, scores, and .5-g hoof samples were obtained from the right front foot of all bulls on d 1 and 112 of four tests conducted in three locations in Arkansas. Data were analyzed using least squares analysis of variance. The model used included terms for an overall mean, test, breed, farm of origin within breed, initial age, and initial weight within breed and residual error. Means were separated using repeated t-test. Residual correlation coefficients were obtained from the residual sum of squares. Test and breed were significant for hoof angle but not for hoof growth, hoof score, and hoof pigment. Farm of origin within breed, initial age, and initial weight within breed were not significant for any hoof trait. The model explained .72, .39, .42, and .83 of the variation (R2) of the main effects of hoof angle, hoof growth, hoof score, and hoof pigment, respectively. Hoof angle for Angus and Brangus bulls was different (P

Data collected from 759 steer calves that were consigned to the South Dakota Retained Ownership Demonstration Program were utilized to examine the effect of slaughter cattle marketing method on production signals sent to beef producers. Marketing systems examined included basing price on live weight (LW), dressed weight (DW), grade and yield (G-Y), or Excel Corporation’s proposed muscle scoring system (MS). Profitability per head averaged $6.64, $23.54, $26.00, and $27.09 for the LW, DW, G-Y, and MS marketing systems, respectively. For the LW pricing system, average daily gain, cost of gain, initial feedlot weight, and days fed accounted for 86.6% of the variation in profitability. For the DW pricing system, average daily gain, dressing percentage, cost of gain, initial feedlot weight, and days fed accounted for 92.86% of the variation in profitability. Average daily gain, dressing percentage, quality grade, cost of gain, days fed, and hot carcass weight accounted for 83.1% of the variation in profit for the G-Y marketing system. Average daily gain, dressing percentage, cost of gain, days fed, carcass fatness, quality grade, and rib eye area explained 75.6% of the variation in profitability for the MS pricing system. Only the MS pricing system penalized the production of carcass fat. Current fed cattle pricing systems used in the industry fail to transfer consumer demand for lean beef to beef producers.

Effects of zeranol and monensin, alone or in combination, on replacement heifer growth and reproductive performance were investigated. Over a period of 6 yr, 311 Hereford x Angus heifers were stratified by age and weight at weaning randomly assigned to one of four treatments: control (C); two 36-mg implants of zeranol administered on d 1 and 96 (Z); 200 mg of monensin, daily (M); or zeranol + monensin (ZM). Diets included meadow hay + 1.4 kg barley + .05 kg of biuret during the 196-d wintering phase. Initial weights averaged 166 kg. Heifers in the M and ZM treatments had 18% greater (P .1) from M or ZM. Zeranol increased (P < .05) the attrition rate of heifers by over 50% compared to C and M in the first calving year. Second breeding attrition rate was higher (P < .01) for C and ZM treatments than for M or Z. Pelvic size tended to be larger (P < .1) at time of breeding in ZM heifers and incidence of dystocia was lower (P < .05) in implanted heifers. Results indicate that two implants of zeranol reduced first calf conception rate, delayed conception, and decreased age of first estrus. An increased attrition rate within the first year was also observed in implanted heifers. Monensin appeared to counteract some of the negative effects of zeranol on reproductive performance and reduced culling rates over the first two calving seasons.

Mature Hereford cows (n = 28) were used to determine the effect of percentage body fat on secretion of LH and content of GnRH in the infundibular stalk-median eminence (ISME). Cows were fed to maintain, lose, or gain weight to achieve body condition scores (BCS; 1 = emaciated; 9 = obese) of 3 to 7. Then cows were fed to maintain weight and body condition. Before slaughter, estrus was synchronized using two injections of prostaglandin F2 alpha(PGF) 11 d apart. Five d after the second PGF injection, cows were given 100 micrograms of GnRH (im) and serum samples were obtained. LH was quantified using RIA. The anterior pituitary and ISME were obtained within 45 min of death. Anterior pituitary weight and LH concentration, total GnRH in the ISME, total carcass fat, and percentage carcass fat were determined. BCS of cows at the time of slaughter influenced percentage carcass fat (P less than .001), total GnRH in the ISME (P less than .02), and maximum LH after GnRH treatment (P less than .09), but did not influence pituitary weight or concentration of LH in the pituitary. Content of GnRH in the ISME averaged 76 +/- 12, 32 +/- 14, 27 +/- 13, and 24 +/- 13 ng for cows with BCS of 3, 5, 6, and 7, respectively. BCS was correlated (P less than .001) with percentage carcass fat (r = .94) and total fat in the carcass (r = .92). Total GnRH in the ISME was negatively correlated (P less than .005) with BCS (r = -.54), percentage carcass fat (r = -.55), and total carcass fat (r = -.49).(ABSTRACT TRUNCATED AT 250 WORDS)

Newer grazing systems such as Intensive Early Stocking and Short Duration Grazing for native ranges and improved pastures typically involve heavier stocking densities than extensive systems. High-quality forages such as small grains are almost always stocked heavily. Because intensively grazed cattle are more likely to be marginally over-stocked and consume slightly less daily forage than cattle grazed extensively, the effect of a supplement on forage intake and digestibility must be considered very carefully. Effects of supplementation on gain per ha must be considered along with gain per animal. Feeding supplements to cattle on high-quality pastures and intensively grazed patterns is most likely to be efficient when forage is limited and supplementation permits a greater carrying capacity. The best supplement ingredients will be those high in digestible fiber and low in starch because forage utilization is not adversely affected. The supplements are safe and gain per ha as well as gain per head may be efficiently enhanced.

Native flood meadows in the northwestern U.S. are typically managed for hay production. However, management for use by grazing livestock is receiving increased interest. Irrigation water is primarily supplied by surface runoff from snowmelt occurring at higher elevations surrounding the meadows. This experiment was conducted to compare strip (SG) and continuous grazing (CG) effects on livestock diet quality and subsequent performance. On May 1, groups of 20 steers (253 kg) were randomly allotted to two replicates of SG and CG treatment pastures (5.6 ha each). Animals in SG pastures were confined by electric fence to an area large enough to provide approximately 65% utilization after a 5- to 7-d grazing period. Average strip size was .5 ha, and varied from .23 to 1.15 ha. Herbage allowance was between 305 to 1131 kg/AU under CG, and 72 to 198 kg/AU for SG treatments, as measured on d 1 in each strip. Biweekly esophageal extrusa samples and total fecal collections showed that over the grazing season, average CP of extrusa samples from CG tended to be higher than SG ( P = .14), at 13.9 and 10.9%, respectively. Crude protein declined signifi-cantly between May and September. Diet IVDDM varied between treatments ( P = .07), at 64.6 and 60.7% on CG and SG, respectively. Grasses were more frequent in extrusa samples from SG than CG ( P = .06), at 49 and 35%, respectively. Meadow foxtail was the most common grass on the meadows and was more frequent in SG extrusa samples ( P = .05). Forage intake was similar ( P = .42) for both treatments, at about 2.1% of body weight per day. Steers were weighed biweekly. Steer average daily gain was greater under CG ( P = .09) (1.16 kg/day) than SG (.77 kg/day).

Three experiments were conducted to evaluate performance and fecal nematode egg counts in grazing stocker cattle receiving morantel tartrate (MT) in two continuously administered forms. In Exp. 1, 80 crossbred steers either received no anthelmintic (C) or were dewormed at the initiation of a 140-d bermudagrass grazing study with either levamisole injection (L) or MT in a sustained-release trilaminate (MSRT). Anthelmintics did not affect performance parameters, but fecal nematode egg counts were lowest from L, intermediate from MSRT, and highest from C at the end of the study. In Exp. 2, 60 crossbred steers grazing fall-regrowth smooth bromegrass were offered a mineral mixture of trace-mineralized salt and dicalcium phosphate (3:1 ratio) with 0 or 10% dried molasses and 0 or 5.58 mg/g MT. Steer gains were similar (P>.10) across treatments, but fecal egg counts were reduced (P

Growth, carcass, and meat quality traits of crossbred intact males and zeranol-implant steers were evaluated. Young bulls grew more rapidly (P

Eighty-eight spring calving and 58 fall calving Hereford and Hereford × Angus cows were wIntered on dormant native tallgrass range to study the value of wheat middlings (WM) as a source of supplemental CP and energy. Supplements consisted of soybean meal (SBM, 40010 CP), SBM and WM (32% CP), WM and SBM (24% CP), and WM (16% CP). Each supplement was individually fed and provided .36 kg CP daily from November 5 to December 9, and .54 kg CP from December 10 to May 4 for spring calving cows. Fall calving cows were fed .36 kg CP daily from November 29 to December 9 and .54 kg from December 10 to March 15. Precalving weight changes for spring calving cows increased linearly (P

Eighty-four spring calving Hereford and Hereford x Angus cows in trial 1 and 96 in trial 2 were grazed on dormant native tallgrass pastures and were Individually fed supplements to evaluate the value of wheat middlings. In trial 1, wheat middlings (WM) were compared to soybean meal (SBM) and isonitrogenous cornlS8M mixtures (16% CP, CIS). Supplements were fed 6 dlwk from November 4 to April 21. Treatments were two levels of CP (.21 or .54 kg) from SBM, WM, or CIS in a 2 by 3 factorial arrangement. Precalving and total winter cow weight changes were improved for WM and CIS compared to SBM when fed .54 kg CP bUlt not the .21 kg CP level. Precalving and winter cow weight and condition changes were similar for WM and CIS at both levels of CP. Pregnancy rates tended (P Trial 2 was conducted to detlermine the amount of WM needed for cows to perform as well as when fed 1.36 kg SBM. Cows were supplemented with 1.36 kg SBM or 2.27,2.84, and 3.41 kg of WM .daily to provide .55, .34, .44, and .55 k,g CP, respectively. Supplements were fed 6 dlwk from November 1 to April 18. Cow weight changes from November 1 to calving increased linearly (P

One hundred twenty crossbred yearling heifers were used to compare a combination of MGA and prostaglandin F 2 α (PGF 2 α) as an estrous synchronization program to a conventional Al program. Heifers were stratified by estrous status (prepuberal or postpuberal) and assigned to receive MGA for 14 d followed by an injection of PGF 2 α 16 d post-MGA feeding (TRT) or to an untreated control group (CON). Puberty was determined by the detection of behavioral estrus or the presence of a palpable corpus luteum arid an increased level of serum progesterone. All heifers were observed for behavioral estrus and bred by Al during a 30-d breeding season. A higher percentage ( P P >.10) for the two groups. A higher percentage ( P 2 α injection (60%) compared with the CON group (5%) during the same time period. A higher percentage ( P 2 α was effective in estrous synchronization.

The feeding of antibiotics or ionophores in free-choice mineral mixtures was evaluated in four studies with stockers (heifers and steers) grazing native range. In trial 1, heifers with access to lasalocid in a free-choice mineral mixture consumed more mineral ( P P P >.05) in daily gain and in ruminal propionic acid. Both groups gained more ( P P P

Two hundred crossbred yearling heifers were used in a 3 x 2 factorial experiment to compare the effectiveness of two estrous synchronization programs (MGA-prostaglandin F 2 α and Syncro-mate-B) with a control group utilizing two types of breeding programs (Al or natural service). Heifers were stratified by estrous status (prepuberal or post-puberal) to one of six treatments. The MGA treatment group received MGA for 14 d followed by an injection of prostaglandin F 2 α (PGF 2 α), 16 d after the last day of MGA feeding. The Syncro-mate-B (SMB) group received the standard 9-d procedure. A third group served as the controls. One-half of the heifers in each of the three treatment groups were bred by Al and the other half by natural service. Yearling bulls were used in a ratio of 1 to 20 females and were rotated among treatment groups at 12-h intervals during the synchronization period. Estrous response rates did not differ ( P >.05) between the MGA and SMB treatment groups for either the Al or natural service heifers. No differences ( P >.05) were found in pregnancy rates during the first 6 d of breeding between MGA and SMB groups whether bred by Al (56 vs. 59%) or natural service (67 vs. 74%). First-service conception rates did not differ ( P >.05) between treatments whether bred by Al or natural service. A higher percentage of the prepuberal heifers exhibited estrus following SMB treatment (100%) compared with controls (38%). Pregnancy rates in 6 and 30 d were slightly higher ( P >.05) in heifers bred by natural service compared with Al. These data indicate both treatments were effective in inducing and synchronizing estrus, and natural service is a viable alternative to Al in synchronization programs.

Data from steers and heifers fed in commercial feedlots in the Texas Panhandle trade area were analyzed to establish an industry baseline for the possible influences of sex, season of year, year, and geographic location (north or south of the Canadian River) upon cattle performance. Number of days steers and heifers were fed was influenced ( P P P P P P P P P

Endophyte-infected fescue hay (EIFH) was harvested during May from a pasture from a 100% Acremonium coenophialum infection. The effects of feeding treatments 1) EIFH, 2) EIFH with lasalocid, 3) ammoniated EIFH, 4) EIFH with acetylsalicylic acid (ASA), 5) EIFH with selenium-zinc-vitamin E (SeZnE), and 6) EIFH with thiabendazole (TBZ) on gain, body temperature, hay consumption, and feed efficiency were evaluated for a 56-d period during September and October. Forty-eight Hereford x Angus steers averaging 207 kg were selected for tendency to elevate body temperature when given access to 100% endophyte-infected fescue pasture. Steers were fed individually and hay was offered at a rate of 2.4% of shrunk body weight, which was adjusted after 28 d. Feed consumption was recorded daily and individual body temperatures were taken twice weekly. Steers were supplemented daily with .9 kg of ground shelled corn containing the specified treatment compound. A mineral mixture was provided free choice. Steers fed the ammoniated EIFH gained more ( P P

Crossbred steers (266 kg avg BW) were allotted to groups and provided either a control mineral mixture or one containing 2.5% zinc methionine while grazing late-spring burned native grass pastures in early summer to determine whether zinc methionine would reduce the incidence of footrot. Four pastures were provided per treatment per year, and the treatments were rotated in each year of a 3-yr study. The steers were weighed individually in early morning at the start of the trial in April and again at the end in late July or early August. The pastures were grazed an average of 93 d. The mineral mixtures were fed in open wooden boxes, and intake was recorded weekly. The steers were checked once each week for signs of footrot. The steers receiving zinc methionine gained faster (1.27 vs 1.23 kg; P < .06) and had a lower incidence of footrot (2.45 vs 5.38%; P < .06) than the control group. However, the difference in gain between steers with footrot and nonaffected steers did not account for the total difference in gain. Zinc methionine at 2.5% of the mineral mixture improved steer gains and reduced the incidences of footrot.

Clenbuterol is a highly specific, long-acting (four to eight hours) beta-two sympathomimetic which causes bronchodilation and tocolysis (myometrial paralysis). The tocolytic effect was explored as a means to control parturition and reduce dystocia. Forty-six heifers were injected i.m. with either Clenbuterol or saline placebo in a randomly controlled experiment. Animals were treated when a cervical dilation of five centimeters or more was detected by vaginal examination. Length of first, second and third stages of parturition, ease of parturition, maternal pelvic area and calf viability were compared between treatment groups. Treatment with Clenbuterol increased (P

Summary Corn gluten feed was evaluated as a supplement for beef cows grazing native range in winter and heifers grazing the same pastures in summer. In 1985 and 1986, 72 mature Hereford cows bred to calve in March and April were divided into four treatments. Treatments and daily feed levels (kg/head) from November to January 30 were: negative control, .5 soybean meal (NC); positive control, .9 soybean meal (SBMI); 1.4 kg/d of 1:2 ratio of soybean meal and corn gluten feed (SBM/CGF); and 2.0 corn gluten feed (CGF). Supplementation began in mid-November and ended as each cow calved. On d 75 (January 30) of the trial, supplement levels were adjusted based on weight changes of negative and positive control cows. All supplement levels were increased by 50% in 1985, and reduced by 33% in 1986. Supplements were prorated and individually fed 6 d per wk. Ruminal pH was lowered (P ◄ .01) at 4 h after feeding CGF supplement. Ruminal ammonia was higher (P ◄ .01) at 4 h after feeding SBM. At both 1 and 4 h after feeding supplements, the proportion of acetate was decreased (P ◄ .01) but propionate and butyrate were increased (P ◄ .01) in cows fed CGF. NC cows lost more weight and body condition (P ◄ .01) than SBM cows, while SBM/CGF and CGF cows maintained body weight and condition similar to cows receiving SBM. Forty-three Hereford and Hereford × Angus heifers in 1985 and 48 in 1986 were similarly fed 5 d each wk from July 16 to October 8 at daily rates of 0, .55, .86, and 1.27 kg/head for NC, SBM, SBM/CGF, and CGF treatments respectively. Heifers receiving SBM gained more weight P ◄ .01) than unsupplemented NC heifers while heifers fed SBM/CGF and CGF gained more weight (P ◄ .01) than heifers fed SBM. Corn gluten feed is an effective energy and protein supplement for beef cows consuming winter native range and for heifers grazing mid- to late-summer range. Utilization of CGF as a supplement is improved when SBM provides one-half of supplemental protein.