Oregon State University's Steer-a-Year program: integrating classroom learning and hands-on experience.

The Steer-a-Year course is designed to provide classroom and hands-on experience, industry-student interaction, and student group problem-solving opportunities. It is a cooperative agreement between the Department of Animal Sciences and the Oregon Cattlemen's and Cattlewomen's Associations. Steers are donated to the program by beef producers, fed a high concentrate ration to a target BW and condition, and marketed as either carcass or retail beef. After feed and management expenses are deducted, the Department of Animal Sciences retains one-half of the profit to be used for beef facilities improvements, and the other half is distributed to the donor's choice of either the Oregon Cattlemen's or Cattlewomen's Association. Approximately 30 steers have been donated to the program annually each of the past eight years. The donor receives updates regarding steer performance during the feeding period and carcass data following harvest of the animal. Students and instructors feed and manage the steers. The instructor uses classroom time to provide information to enable students to make informed management decisions. Officers are elected from within the class each term. Student officers are responsible for ensuring that cattle are managed and fed appropriately, and they lead the class in writing and sending producer updates. An evolving facet of the program is processing and marketing. Steers are sold locally through the Clark Meat Science Center. Students are encouraged to participate in a separate course in which they process the steers into retail product. In this manner, students can be involved in procurement, management, processing, and marketing. The course is challenging for the instructor since it requires management of lecture material, cattle health and feeding, producer and employee rapport, and student participation to ensure annual success of the program in terms of student learning and public relations. The course is very well received by students, most of whom have labeled it as a great learning experience.

Responses of the bovine infundibulum to noradrenaline during the oestrous cycle.

An experiment was conducted to investigate the responses of the bovine infundibulum to noradrenaline in vitro. Twelve beef heifers were killed and examined in equal numbers during pro-oestrus and dioestrus (day 12 of the oestrous cycle). A jugular blood sample was collected from each heifer immediately before killing, and the sera were subsequently analysed by radioimmunoassay for progesterone and oestradiol. A strip of each infundibulum (ipsilateral and contralateral to the ovary bearing the largest follicle or functional corpus luteum) was placed into a tissue bath and sequentially exposed to increasing concentrations of noradrenaline (0.4, 0.8 and 1.6 micrograms ml-1). Changes in frequency and amplitude of isometric contractions and tissue tone were recorded. Infundibula ipsilateral to ovaries bearing the largest follicle in pro-oestrous heifers responded to all concentrations of noradrenaline with greater frequency of contractions than did either contralateral infundibula or both ipsilateral and contralateral infundibula of dioestrous animals (stage of cycle x tissue location interaction, P < 0.01). Changes in the amplitude of contractions induced by noradrenaline did not differ between stages of the cycle studied or the location of the infundibulum within the animal. Mean tone of ipsilateral and contralateral infundibula of pro-oestrous and dioestrous animals increased linearly with exposure to all concentrations of noradrenaline tested (P < 0.05). However, the response of infundibula of dioestrous animals was greater than that of infundibula of pro-oestrous heifers (P < or = 0.06). These data demonstrate that the bovine infundibulum is responsive to noradrenaline, and suggest that responses to this neurotransmitter may be governed by concentrations of oestrogen and progesterone to which the infundibulum is exposed.

Safety, efficacy, and effects on copper metabolism of intrareticularly placed selenium boluses in beef heifer calves.

Intrareticularly placed sustained-release selenium boluses were administered to 1 group of selenium-deficient heifer calves (n = 16), and a second group (n = 16) was left as nontreated controls. Age range for all calves was 83 to 156 days. These boluses release 3 mg of selenium each day, as sodium selenite. Measurements of blood selenium concentration, plasma copper concentration, hepatic copper concentration, and body weight were made over a 188-day study. The treated group of calves had significantly higher mean blood selenium concentration at posttreatment days 68 (P < 0.0001), 112 (P < 0.0001), and 188 (P < 0.005) than did the control group. Mean blood selenium concentration in the treated calves was > 0.10 micrograms/ml for 188 days. These boluses were observed to be clinically safe; signs of selenium toxicosis were not detected and untoward effects were not seen in the selenium-treated calves. There were no differences between control and treatment groups with respect to mean hepatic copper concentration or mean plasma copper concentration. There were no observed differences between the control and treatment groups with respect to weight gain during the study.

Comparison of whole, raw soybeans, extruded soybeans, or soybean meal and barley on digestive characteristics and performance of weaned beef steers consuming mature grass hay.

Two experiments were conducted to compare whole, raw soybeans (WSB), extruded soybeans (ESB), and soybean meal+barley (SBM+BAR) as supplemental protein sources for growing beef steers consuming low-quality, mature grass hay (6.5% CP). In Exp. 1, a 23-d digestion study, four ruminally cannulated steers were assigned to the following treatments in a 4 x 4 Latin square design: 1) control, no supplement; 2) 1.5 kg.animal-1.d-1 of WSB; 3) 1.36 kg.animal-1.d-1 of ESB; and 4) 1.48 kg.animal-1.d-1 of 62%:38% SBM+BAR. Apparent DM digestibility was increased by supplementation (P < .10), but NDF digestibility was not changed (P > .10). No differences in digestibility were observed among supplement treatments (P > .10). In situ rate and extent of supplement CP disappearance in Dacron bags did not differ among supplements (P > .10), but extent of DM disappearance was greater for WSB than for ESB (P < .10). In situ rate of forage NDF disappearance was decreased by protein supplementation (P = .10). In Exp. 2, 40 Polled Hereford and Red Angus x Simmental weanling steer calves were stratified by weight (average BW, 250 kg) and allotted randomly to one of two replications of the four treatments used in Exp. 1 (eight pens, five animals per pen). Forage DMI was not affected by treatment (P > .10). Average daily gain and feed efficiency were increased by supplementation (P < .05). Supplement source had no effect on intake or ADG (P > .10), but ESB tended to exhibit better feed efficiency than WSB (P = .10). In conclusion, WSB and ESB seem to be as effective as SBM+BAR protein supplements for growing beef cattle. In addition, WSB and ESB, at the levels used in these experiments, can be incorporated into diets for cattle consuming low-quality roughage without deleterious effects on fiber digestion or subsequent performance.

The correlation between serum selenium and blood selenium in cattle.

The selenium (Se) concentration of paired blood and serum samples from cattle was determined by 2 methods: 1) atomic absorption spectroscopy using hydride generation (HG-AAS), and 2) inductively coupled argon plasma emission spectroscopy using hydride generation (ICP). Samples from 327 cattle were analyzed by HG-AAS, and samples from 344 cattle were analyzed by ICP. The data were examined by linear regression analysis, and the technique of inverse prediction was utilized to determine prediction intervals for estimating blood Se concentration from known serum Se concentration. The correlation coefficients, by simple linear regression of serum Se on blood Se, were 0.79 (r2 = 0.62) and 0.88 (r2 = 0.77) for the HG-AAS data and the ICP data, respectively. For the HG-AAS data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. For the ICP data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. The prediction intervals were quite wide, and the accuracy of estimating blood Se from a known serum Se was not useful for diagnostic purposes. The use of serum Se concentration to assess nutritional status of cattle with respect to Se does not appear to be appropriate.

Safety and efficacy of two sustained-release intrareticular selenium supplements and the associated placental and colostral transfer of selenium in beef cattle.

One hundred fifty Se-deficient, pregnant, crossbred beef cows were assigned to 1 of 4 treatment groups: group A, Se-deficient control; group B, 1 Se bolus at 0 and 119 days; group C, 1 Se bolus at 0 days; and group D, 2 Se pellets at 0 days. The Se bolus is an osmotic pump designed to release 3 mg of Se/d into the reticulorumen. The Se pellets weight approximately 30 g and contain 10% elemental Se, which is liberated in the reticulorumen. The Se bolus is designed to provide Se supplementation for 120 days and the Se pellets provide supplementation for up to 18 months. Cattle were maintained on Se-deficient pasture or forages prepared from these pastures for the duration of the experiment. Blood samples were collected from cows prior to treatment (time 0) and at 28, 52, 119, and 220 days thereafter and analyzed for blood Se (BSe) concentration. Body weights were recorded at each sampling time. Blood Se concentration of cows from all supplemented groups were significantly (P less than 0.01) higher than control values at all sample dates after treatments began. By the end of the 220-day study, treatment group-B cattle had significantly (P less than 0.01) higher BSe concentrations than any other group. Body weights of treatment groups fluctuated throughout the study, but did not differ (P greater than 0.05) between groups. One cow and 6 calves born to cows during the experimental period died. Necropsy of 5 calves provided no evidence linking these deaths to treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Crossbreeding among British and continental European dual-purpose breeds in the coastal Pacific Northwest.

From 1979 through 1987, British breed and crossbred cows were mated to Simmental, Pinzgauer or Tarentaise bulls or to Hereford-Angus crossbred bulls. Beginning in 1982, continental European crossbred females also entered the herd, to be mated for first calving to Hereford-Angus or Angus bulls and as cows to continental European or Hereford-Angus bulls. In progeny of British breed and crossbred cows, dam breed effects on birth and weaning weight were not important, but continental European crossbred calves were heavier than British crossbred contemporaries at birth and weaning. Pinzgauer- and Simmental-sired calves were heavier at birth than Tarentaise crosses, but calves sired by each of the continental breeds had similar weaning weights. Maternal heterosis was greater than direct heterosis effects on weaning weight (8% vs 5%), but only direct heterosis (13%) influenced birth weight. Within progeny of continental European crossbred cows, calves with a Tarentaise maternal grandsire were lighter at birth, with no significant difference among other maternal grandsire breeds. Maternal breed effects on weaning weight were not significant. Nevertheless, in contemporary years, continental European crossbred cows reared calves that were 10% heavier than calves reared by British crossbred cows. Pacific Northwestern cattle producers could achieve substantial increases in weaning weight from introducing inheritance from continental European dual-purpose breeds into cow herds and calf crops of British ancestry.

Efficacy of the morantel sustained release trilaminate matrix against gastrointestinal nematodes in beef calves.

The effectiveness of the morantel sustained release trilaminate (MSRT) in controlling gastrointestinal nematodes through a grazing season was evaluated using 60 yearling beef stocker calves randomly divided into 2 groups of 30 animals each. In April 1985, the calves comprising the treatment group each received an MSRT designed to release morantel tartrate continuously for 90 days while those of the control group remained unmedicated. All animals were weighed and samples of rectal feces were taken at 14-day intervals, beginning on Day 0, until trial termination (Day 168). At trial termination, 10 control and 10 treated calves were necropsied for recovery of gastrointestinal nematodes. Three sets of parasite-naïve tracer calves were utilized to evaluate the initial, interim and final levels of pasture contamination by nematode larvae. Overall, the use of the MSRT resulted in a 75.5% reduction (P less than 0.001) in output of nematode eggs from the principals, an 81.8% reduction (P less than 0.001) in numbers of gastrointestinal nematodes in principals (at trial termination), and a 96.9% reduction (P less than 0.05) of pasture larval nematode contamination (as indirectly indicated by parasite burdens in tracer calves). The mean weight advantage of treated calves was 16.6 kg per head (P less than 0.001).

Anthelmintic efficacy of netobimin against naturally acquired gastrointestinal nematodes in yearling heifers.

The efficacy of netobimin (Coded SCH 32481, Schering Corporation) in removing naturally acquired gastrointestinal nematode infections was evaluated in 10 treated and 10 untreated (control) yearling beef heifers. The anthelmintic was administered as an oral drench at a dose level of 7.5 mg kg-1 body weight. Fecal egg per gram (EPG) counts were reduced with netobimin by 98% (P less than or equal to 0.01) at both 1 and 2 weeks post-treatment (PT). The compound was highly effective in removing Oesophagostomum radiatum (100% at P less than or equal to 0.01), Cooperia spp. (97.66% at P less than or equal to 0.01) and Nematodirus helvetianus (100%, although not significant), but was ineffective against immature Ostertagia ostertagi (3.19%) and only moderately effective against adult forms (66.14% at P less than or equal to 0.05). The low efficacy against adult O. ostertagi was partially attributed to the maturation of fourth-stage larvae, not removed by the 7.5 mg kg-1 treatment, during the 14-day treatment-slaughter interval. Efficacy against Trichuris spp. could not be evaluated due to low levels and unequal numbers of worms recovered in the groups. The overall efficacy against adult species, excluding Trichuris spp., was 67.40% (P less than or equal to 0.05). No adverse reactions or signs of toxicosis were observed in heifers treated with netobimin.

Effect of lasalocid on fall-calving beef cows.

The effects of lasalocid on fall-calving beef cows were examined in a 196-d trial that began October 12, 1983. Forty-two crossbred cow-calf pairs were stratified to six groups by breed, calving date and sex of calf. Three replications of each of two treatments, 0 and 200 mg lasalocid X head-1 X d-1, were used. The cows were fed a combination of haylage and grass hay ad libitum. The cow-calf pairs were allowed access to pasture at all times, except during the breeding season. At this time they were kept in confinement to facilitate heat detection and artificial insemination. Cow weight changes and body condition (0 = very thin, 9 = very fat) were unaffected (P greater than .10) by feeding lasalocid to the cows. Twelve-hour milk production per cow, percent fat and percent protein were each determined three times during the trial. A slight increase in milk yield was observed in treated cows (P greater than .10). Percent milk fat and protein were also unaffected by treatment (P greater than .10). Lasalocid supplementation of cows did not affect calf gain or 205-d adjusted weaning weight (P greater than .10). Average days open was evaluated for the cows. There were no differences between treatments for actual average days open (P greater than .10). No detrimental effects were observed in long-term feeding of lasalocid to fall-calving beef cows.