Infectious Bovine Rhinotracheitis Virus Antibody Responses to Vaccines Used in Combination

The objective of this experimentation was to determine if circulating antibody titers to parainfluenza type-3 (PI-3) and infectious bovine rhinotracheitis (IBR) viruses could be enhanced by a combination of vaccines. The vaccines utilized were a modified live virus vaccine administered by the intranasal route and an inactivated virus vaccine injected intramuscularly. Virus neutralization tests were conducted on sera obtained at intervals before and following vaccination. Unfortunately, the calves were apparently exposed naturally to PI-3 virus, and the responses to that virus were inconclusive. However, antibody responses to IBR virus were dramatically enhanced by the combination of the two vaccines.

Antibody Responses of Young Calves to Inactivated Viral Vaccines

Three commercial inactivated virus vaccines were evaluated for immunogenicity in young calves with residual maternal antibodies. Groups of 30 calves were administered each of the vaccines at the start of the experimentation and were administered a second dose 32 days later. Serum was obtained from these calves and 30 calves in a nonvaccinated control group prior to vaccination and at 32, 61, 99 and 125 days thereafter. Antibody responses to viruses in two of the vaccines were extremely limited. The third vaccine overcame suppression by maternal antibodies and elicited responses clearly differentiated from antibody levels in the control group of calves.

The Effects of Low Dose Irradiation and Storage Time on Aroma of Fresh Beef Patties in Anaerobic Packaging

The effects of electron beam irradiation, anaerobic packaging, and storage times on the aroma of raw ground beef patties were investigated. Patties were coarse ground at three days postmortem, and then fine ground and packaged at three, six, and nine days postmortem. Patties were irradiated immediately after packaging, or three days after packaging at 2 kGy, and then stored at 2.5 °C ñ1.5 °C for four days. Non-irradiated controls were held under similar conditions. After four days of storage for each postmortem time (three, six, and nine days), sensory aroma evaluations were performed on all samples. Irradiated and non-irradiated patties with the shortest postmortem storage times had the most desirable aroma scores. Controls had significantly (p £ .05) more desirable aroma scores than irradiated patties.

Experiences with Grid Marketing - Summary of Chariton Valley Beef Sales for Year 2000

Producers in the Chariton Valley Beef organization have marketed more than 10,000 head of cattle into grid markets over the past three years. Data from 134 lots were summarized, with 3,791 head of cattle marketed into four grid markets. Producers averaged $26.05 per head premiums. Premiums and discounts ranged from a positive $79.01 to a negative $40.44 on tots delivered.

Pasture Weaning at the McNay Memorial Research and Demonstration Farm: A Progress Report

In September 1995, 225 spring-born calves were weaned on pasture at the McNay Memorial Research and Demonstration Farm to explore procedures necessary to conduct a successful pasture-weaning program. In the two to three week post-weaning period, average daily gains (ADG) for the two groups weaned that year were 1.06 and 3.06 pounds; there were no health problems. In 1996, a research trial utilizing 242 spring-born calves was conducted to compare pastureweaned and feedlot-weaned calves. Half of the calves were weaned on pasture for three weeks and then placed in a feedlot for three more weeks. The other half of the calves were weaned directly into the feedlot for the six week post-weaning period. ADGs during the three week post-weaning period were 1.24 and 2.42 for the pastureweaned and feedlot-weaned calves. For the entire six week trial, ADGs were 1.83 and 2.40 for the pastureweaned and feedlot-weaned calves. There was no sickness in either weaning treatment during the six week trial. Initial experience indicates pasture-weaning is a feasible method of getting calves through a stressful procedure.

Critical Control Points for Profitability in the Cow-Calf Enterprise

Financial, economic, and biological data collected from cow-calf producers who participated in the Illinois and Iowa Standardized Performance Analysis (SPA) programs were used in this study. Data used were collected for the 1996 through 1999 calendar years, with each herd within year representing one observation. This resulted in a final database of 225 observations (117 from Iowa and 108 from Illinois) from commercial herds with a range in size from 20 to 373 cows. Two analyses were conducted, one utilizing financial cost of production data, the other economic cost of production data. Each observation was analyzed as the difference from the mean for that given year. The independent variable utilized in both the financial and economic models as an indicator of profit was return to unpaid labor and management per cow (RLM). Used as dependent variables were the five factors that make up total annual cow cost: feed cost, operating cost, depreciation cost, capital charge, and hired labor, all on an annual cost per cow basis. In the economic analysis, family labor was also included. Production factors evaluated as dependent variables in both models were calf weight, calf price, cull weight, cull price, weaning percentage, and calving distribution. Herd size and investment were also analyzed. All financial factors analyzed were significantly correlated to RLM (P < .10) except cull weight, and cull price. All economic factors analyzed were significantly correlated to RLM (P < .10) except calf weight, cull weight and cull price. Results of the financial prediction equation indicate that there are eight measurements capable of explaining over 82 percent of the farm-to-farm variation in RLM. Feed cost is the overriding factor driving RLM in both the financial and economic stepwise regression analyses. In both analyses over 50 percent of the herd-to-herd variation in RLM could be explained by feed cost. Financial feed cost is correlated (P < .001) to operating cost, depreciation cost, and investment. Economic feed cost is correlated (P < .001) with investment and operating cost, as well as capital charge. Operating cost, depreciation, and capital charge were all negatively correlated (P < .10) to herd size, and positively correlated (P < .01) to feed cost in both analyses. Operating costs were positively correlated with capital charge and investment (P < .01) in both analyses. In the financial regression model, depreciation cost was the second critical factor explaining almost 9 percent of the herd-to-herd variation in RLM followed by operating cost (5 percent). Calf weight had a greater impact than calf price on RLM in both the financial and economic regression models. Calf weight was the fourth indicator of RLM in the financial model and was similar in magnitude to operating cost. Investment was not a significant variable in either regression model; however, it was highly correlated to a number of the significant cost variables including feed cost, depreciation cost, and operating cost (P < .001, financial; P < .10, economic). Cost factors were far more influential in driving RLM than production, reproduction, or producer controlled marketing factors. Of these cost factors, feed cost had by far the largest impact. As producers focus attention on factors that affect the profitability of the operation, feed cost is the most critical control point because it was responsible for over 50 percent of the herd-to-herd variation in profit.

Integration of Year-round Forage Management Systems for Spring-calving and Fall-calving Beef Cows (A Progress Report)

Animal production, hay production and feeding, winter forage composition changes, and summer pasture yields and nutrient composition of a year-round grazing system for spring-calving and fall-calving cows were compared to those of a conventional, minimal land system. Cows in the year-round and minimal land systems grazed forage from smooth bromegrassorchardgrass-birdsfoot trefoil (SB-O-T) pastures at 1.67 and 3.33 acres, respectively, per cow in the summer. During the summer, SB-O-T pastures in the year-round grazing system also were grazed by stockers at 1.67 stockers per acre, and spring-calving and fall-calving cows grazed smooth bromegrass–red clover (SB-RC) and endophyte-free tall fescue–red clover (TF-RC) at 2.5 acres per cow for approximately 45 days in midsummer. In the year-round grazing system, spring-calving cows grazed corn crop residues at 2.5 acres per cow and stockpiled SB-RC pastures at 2.5 acres per cow; fallcalving cows grazed stockpiled TF-RC pastures at 2.5 acres per cow during winter. In the minimal land system, in winter, cows were maintained in a drylot on first-cutting hay harvested from 62.5–75% of the pasture acres during summer. Hay was fed to maintain a body condition score of 5 on a 9-point scale for springcalving cows in both systems and a body condition score of 3 for fall-calving cows in the year-round system. Over 3 years, mean body weights of fall-calving cows in the year-round system did not differ from the body weights of spring-calving cows in either system, but fall-calving cows had higher (P < .05) body condition scores compared to spring-calving cows in either system. There were no differences among all groups of cows in body condition score changes over the winter grazing season (P > .05). During the summer grazing season, fall-calving cows in the year- round system and springcalving cows in the minimal land system gained more body condition and more weight (P < .05) than springcalving cows in the year-round grazing system. Fall calves in the year-round system had higher birth weights, lower weaning weights, and lower average preweaning daily gains compared to either group of spring calves (P < .05). However, there were no significant differences for birth weights, weaning weights, or average pre-weaning daily gains between spring calves in either system over the 3-year experiment (P > .05). The amount of total growing animal production (calves and stockers) per acre for each system did not differ in any year (P > .05). Over the 3-year experiment, 1.9 ton more hay was fed per cow and 1 ton more hay was fed per cow–calf pair in the minimal land system compared to the year-round grazing system (P < .05).

Effects of Pasture Conditions in Spring on Seasonal Forage Productivity

Fifteen beef cow-calf producers in southern Iowa were selected based on locality, management level, historical date of grazing initiation and desire to participate in the project. In 1997 and 1998, all producers kept records of production and economic data using the Integrated Resource Management-Standardized Performance Analysis (IRM-SPA) records program. At the initiation of grazing on each farm in 1997 and 1998, Julian date, degree-days, cumulative precipitation, and soil moisture, phosphorus, and potassium concentrations were determined. Also determined were pH, temperature, and load-bearing capacity; and forage mass, sward height, morphology and dry matter concentration. Over the grazing season, forage production, measured both by cumulative mass and sward height, forage in vitro digestible dry matter concentration, and crude protein concentration were determined monthly. In the fall of 1996 the primary species in pastures on farms used in this project were cool-season grasses, which composed 76% of the live forage whereas legumes and weeds composed 8.3 and 15.3%, respectively. The average number of paddocks was 4.1, reflecting a low intensity rotational stocking system on most farms. The average dates of grazing initiation were May 5 and April 29 in 1997 and 1998, respectively, with standard deviations of 14.8 and 14.1 days. Because the average soil moisture of 23% was dry and did not differ between years, it seems that most producers delayed the initiation of grazing to avoid muddy conditions by initiating grazing at a nearly equal soil moisture. However, Julian date, degree-days, soil temperature and morphology index at grazing initiation were negatively related to seasonal forage production, measured as mass or sward height, in 1998. And forage mass and height at grazing initiation were negatively related to seasonal forage production, measured as sward height, in 1997. Moreover, the concentrations of digestible dry matter at the initiation of and during the grazing season and the concentrations of crude protein during the grazing season were lower than desired for optimal animal performance. Because the mean seasonal digestible dry matter concentration was negatively related to initial forage mass in 1997 and mean seasonal crude proteins concentrations were negatively related to the Julian date, degree-days, and morphology indeces in both years, it seems that delaying the initiation of grazing until pasture soils are not muddy, is limiting the quality as well as the quantity of pasture forage. In 1997, forage production and digestibility were positively related to the soil phosphorus concentration. Soil potassium concentration was positively related to forage digestibility in 1997 and forage production and crude protein concentration in 1998. Increasing the number of paddocks increased forage production, measured as sward height, in 1997, and forage digestible dry matter concentration in 1998. Increasing yields or the concentrations of digestible dry matter or crude protein of pasture forage reduced the costs of purchased feed per cow.

A 13-Year Summary of the ISU Beef Cow Business Record

A 13-year summary of the Iowa State University Extension Service’s Beef Cow Business Record (BCBR) was compiled to show the trends in cost, profit, and production for beef-cow enterprises in Iowa. During these 13 years, 966 yearly records were summarized on herds with an average size of 74.6 cows. Each year-end summary sorts the producers with profits in the top and the bottom thirds of the group so that differences can be analyzed. The average cost to maintain a beef cow from 1982 to 1994 was $370.80. Cost components included in this average total were: feed and pasture, $177.10; operating, $45.40; depreciation, taxes, and insurance, $19.70; labor, $44.90; and capital, $83.70. Producers sorted into the top one-third profit group had 13-year average total cow costs of $309.80, but the bottom onethird profit group averaged $437.10. Economic returns per cow for these same 13 years were: return to capital, labor, and management, $139.50; return to labor and management, $56.20; and net profit, $20.20. Top-profit producers had an average net profit of $126.20 per cow, whereas the least profitable group had an average loss of $107.40. Of this $233.60 difference, $127.30 was due to production cost, and the remaining $106.30 was caused by gross return differences. The average number of pounds of beef produced per cow from 1984 through 1994 was 567. This production was achieved with 2.5 acres of pasture, 3.9 acres of cornstalk grazing, and 4,675 pounds of stored feed per cow unit. Top-profit producers used 673 pounds of stored feed per hundredweight of production, but the least profitable producers used 1,015 pounds. Top-profit producers produced 74 pounds more per cow while using 1,313 pounds less stored feed.

A Historical Review of the 4-H Beef of Merit Carcass Contest at the Iowa State Fair

A total of 1,033 head of steers competing in the Iowa State Fair Beef of Merit class from 1975 through 2000 were summarized. Those grading low Choice and higher averaged 55.4 percent, and the average yield grade was 2.44. Due to rule changes over time the quality grade and cutability shifted. In recent years with the emphasis placed on acceptable quality grade and carcass weight, the BOM cattle have improved dramatically in the percent grading Prime and upper Choice. However, with this change has been a reduction in the percent of cattle making yield grade 1 and 2. Growth rate increased through the late 1980s, but has remained static since that time.

Standardized Performance Analysis (SPA) Summary for 1999-2000 Veterinary Medicine Students

Nine Iowa State University veterinary medical students completed SPA records on herds from Iowa, North Dakota and South Dakota. The Iowa herds were included in the SPA summary for Iowa, but the six North and South Dakota herds were summarized separately. These six herds had an average herd size of 371 cows and had a financial return to capital, labor and management of $175 per cow. Total financial cost per cow averaged $286 for these herds with a range of $211 to $388. Feed utilized averaged 4,442 pounds of dry matter per cow and the average pounds of calf produced per exposed female was 506 pounds.

An Economic Comparison of Rotational Grazing Systems to Eight Crop Alternatives and the CRP Option for Highly Erodible Land in Southwest Iowa

Economic comparisons of income on highly erodible land (HEL) in Adams County were made utilizing five years of grazing data collected from a 13- paddock intensive-rotational grazing system and a four-paddock rotational-grazing system and four years of data collected from an 18-paddock intensive-rotational grazing system, all at the Adams County CRP Research and Demonstration Farm near Corning. Net income from the average grazing weight-gain of Angus-sired calves nursing crossbred cows was compared to the net income from grazing yearling steers, to the net income of eight NRCS-recommended crop rotations, and to the Conservation Reserve Program (CRP) option. Results of these comparisons show the 13-paddock intensive rotational grazing system with cow-calf pairs to be the most profitable alternative, with a net return of $19.86 per acre per year. The second most profitable alternative is the CRP option, with a net return of $13.09 per acre, and the third most profitable option is the fourpaddock rotation with cows and calves with a net return of $12.53 per acre. An 18-paddock system returned a net income of $2.47 per acre per year with cows and calves in 1993, but lost an average of $107.69 per acre each year in 1994 and 1995 with yearling steers. Each year, the steers were purchased high and sold low, contributing to the large loss per acre. The following recommended crop rotations all show net losses on these 9-14 % slope, Adair-Shelby Complex soils (ApD3): continuous corn; corn-soybean rotation; corn-soybean rotation with a farm program deficiency payment; corn-corn-corn-oats-meadow-meadow rotation with grass headlands; continuous corn to “T” with grass headlands and buffer strips; continuous corn to “T” with grass headlands, buffer strips, and a deficiency payment; corn-corn-oats-meadow rotation to “T”; and corn-soybeans-oats-meadow-meadow-meadow-meadow rotation to “T”. Per-acre yield assumptions of 90 bushels for corn, 30 bushels for soybeans, 45 bushels for oats, and four tons for alfalfa were used, with per-bushel prices of $2.40 on corn, $5.50 on soybeans, and $1.50 on oats. Alfalfa hay was priced at $40.00 per ton and grass hay at $33.33 per ton. The calf weight-gain in the cow/ calf systems was valued at $.90 per pound. All crop expenses except land costs were calculated from ISU publication Fm 1712, “Estimated Costs of Crop Production in Iowa - 1995.” Land costs were determined by using an opportunity cost and actual property tax figures for the land at the grazing site. In preparation for the end of the CRP beginning in 1996, further economic comparisons will be made after additional grazing seasons and data collection. This project is an interagency cooperative effort sponsored by the Southern Iowa Forage and Livestock Committee which has special permission from the USDA Farm Service Agency (FSA) to use CRP land for research and demonstration.

A Survey of Forage Quality Following a Flood Year: 1994

A team of extension livestock specialists and county extension workers collected 362 forage samples from cooperating producers in 55 Iowa Counties. Summaries of the three forage types showed normal feed analysis for energy and protein. Micro minerals were also analyzed with 11% of samples being below National Research Council 1984 selenium and zinc requirements for beef.

Pasture Conditions at the Initiation of Grazing to Optimize Forage Productivity: A Progress Report

To determine environmental, soil, and sward effects at the initiation of cattle grazing in the spring on seasonal (forage accumulated during the grazing season) and cumulative (seasonal + initial forage mass) forage accumulation (FA), 15 commercial cow-calf producers from southern Iowa were selected by historical initial grazing date. At grazing initiation, twelve .25-m2 samples were hand-clipped from each pasture and sward heights (SH) measured with a falling plane meter (4.8 kg/m2) to determine initial forage mass. At each location, soil temperature and load bearing capacity (LBC) were measured and a soil sample was collected to measure pH and moisture, P, and K concentrations. Cumulative degree-days (base=3.85°C) and precipitation at grazing initiation were calculated from NOAA records. At the beginning of each month, at least three grazing exclosures were placed on each grazed pasture to determine monthly FA. SH in each exclosure was recorded, and a .25-m2 forage sample was hand-clipped proximate to each exclosure. At the end of each month, SH was recorded and .25-m2 hand-clipped forage samples from inside exclosures were obtained. In linear regressions, cumulative and seasonal SH increased with greater soil P (r2=.5049 and .5417), soil K (r2=.4675 and .4397), and initial forage mass (r2=.1984 and .2801). Seasonal SH increased with earlier initial grazing dates (r2=.1996) and less accumulated degree-days (r2=.2364). Cumulative and seasonal FA increased with earlier initial grazing dates (r2=.2106 and .3744), lower soil temperatures (r2=.2617 and.2874), and greater soil P (r2=.3489 and .2598). Cumulative FA increased with greater soil K (r2=.4675). In quadratic regressions, cumulative and seasonal SH were correlated to soil P (r2=.6310 and .5310) and soil K (r2=.5095 and.4401). Cumulative and seasonal FA were correlated to degree days (r2=.3630 and.4013) and initial grazing date (r2=.3425 and .4088). Cumulative FA was correlated to soil P (r2=.3539), and seasonal FA was correlated to soil moisture (r2=.3688).