Effects of Stocking Density on Steer Performance and Carcass Characteristics in Bedded Hoop Barns

Use of bedded hoop barns for feeding cattle has grown in part due to increased regulations regarding open feedlot runoff. In 2010, ISU estimated almost 700 hoop barns in Iowa used for beef cattle and more than 80% were used for cattle feeding. Work in Iowa also has documented that cattle confined in a bedded hoop barn perform similarly to cattle fed in an open feedlot with shelter. The work was done with a stocking density of 50 sq ft per steer in the bedded hoop barn. A hoop barn is a more expensive facility system compared with open lot configurations. Fixed costs per steer (facilities) are partially determined by stocking density. The objective of this study was to determine the effects of increased stocking density on performance and carcass characteristics of steers fed in bedded hoop and bedded open front facilities. The trials were conducted in 2008 to 2011 at the ISU Armstrong Research Farm, Lewis, IA. The hoop barn was stocked with 40, 45 and 50 head per pen resulting in 50, 45 and 40 sq ft per steer, respectively. There was one stocking density per housing type per trial. The diet fed was 45.0% dry corn, 14.8% ground hay, 36.8% modified distillers grains and 3.4% supplement on an as-fed basis. The total diet was approximately 69% dry matter. Cattle growth rate (ADG), feed intake (DMI), feed efficiency (F/G) and mean mud score did not differ based on stocking density (P\u3e0.05). However, the cattle given more square feet numerically had greater feed intake and were more efficient (about 4-5%) than the more densely stocked cattle. This study may not have had enough replications to detect statistically significant differences. Also the mean carcass characteristics (fat cover, rib eye area, marbling score, quality grade and yield grade) did not differ by stocking density (P\u3e0.05). When comparing seasons only, steers fed in summer tended to have heavier market liveweight, heavier carcass weight, required less feed per liveweight and less marbling compared with steers fed in winter (P≤0.10). Also, the summer-fed steers grew faster and gained more liveweight than the winter-fed steers (P\u3c0.005). These results suggest that this study may not have reached the maximum stocking density for feeding beef cattle in a bedded hoop barn. In other words, market cattle can probably be stocked at less square footage per steer than the 40 sq ft per steer used in this study. Observations of farmers with hoop barns suggest that 37 or 35 sq ft per steer may be feasible. Several factors may affect stocking density including genetics or frame size of the cattle and may interact with season. Also, it should be noted that as the density of cattle increases, more management is required, i.e., more bedding, more bunk space, more waterer space and observing individual cattle for health issues becomes more difficult

Gene doctoring: a method for recombineering in laboratory and pathogenic Escherichia coli strains

Background: Homologous recombination mediated by the lambda-Red genes is a common method for making chromosomal modifications in Escherichia coli. Several protocols have been developed that differ in the mechanisms by which DNA, carrying regions homologous to the chromosome, are delivered into the cell. A common technique is to electroporate linear DNA fragments into cells. Alternatively, DNA fragments are generated in vivo by digestion of a donor plasmid with a nuclease that does not cleave the host genome. In both cases the lambda-Red gene products recombine homologous regions carried on the linear DNA fragments with the chromosome. We have successfully used both techniques to generate chromosomal mutations in E. coli K-12 strains. However, we have had limited success with these lambda-Red based recombination techniques in pathogenic E. coli strains, which has led us to develop an enhanced protocol for recombineering in such strains. \ud \ud Results: Our goal was to develop a high-throughput recombineering system, primarily for the coupling of genes to epitope tags, which could also be used for deletion of genes in both pathogenic and K-12 E. coli strains. To that end we have designed a series of donor plasmids for use with the lambda-Red recombination system, which when cleaved in vivo by the I-SceI meganuclease generate a discrete linear DNA fragment, allowing for C-terminal tagging of chromosomal genes with a 6xHis, 3xFLAG, 4xProteinA or GFP tag or for the deletion of chromosomal regions. We have enhanced existing protocols and technologies by inclusion of a cassette conferring kanamycin resistance and, crucially, by including the sacB gene on the donor plasmid, so that all but true recombinants are counter-selected on kanamycin and sucrose containing media, thus eliminating the need for extensive screening. This method has the added advantage of limiting the exposure of cells to the potential damaging effects of the lambda-Red system, which can lead to unwanted secondary alterations to the chromosome. \ud \ud Conclusion: We have developed a counter-selective recombineering technique for epitope tagging or for deleting genes in E. coli. We have demonstrated the versatility of the technique by modifying the chromosome of the enterohaemorrhagic O157:H7 (EHEC), uropathogenic CFT073 (UPEC), enteroaggregative O42 (EAEC) and enterotoxigenic H10407 (ETEC) E. coli strains as well as in K-12 laboratory strains

Nutrient Retention Performance of a Crushed Limestone Floor Surface in a Bedded Hoop Barn with Confined Beef Cattle

Bedded confinement systems with partial concrete floors are increasingly being adopted by beef cattle feeders. The objective of this study was to determine the extent that manure nutrients moved into the soil below the geotextile fabric and packed limestone screenings floor of a bedded hoop barn used for beef cattle feeding at the ISU Armstrong Research and Demonstration Farm. Soil samples were taken (shallow and deep) before construction in 2004 and in 2008 after 7 groups of cattle were fed. Although single samples before and after animal feeding cannot provide conclusive evidence of moisture or nutrient migration, comparison of the sample results confirm a trend consistent with slow migration of manure nutrients into the soil profile. Phosphorus, calcium and magnesium did not show consistent or major trends with time. Organic matter showed a consistent increasing trend in both shallow and deep samples. Shallow sampling showed a marked increase only in nitrate-nitrogen, from 1.51 ppm to 11.47 ppm. These results are consistent with measurable, but very slow migration of moisture and nutrients into the soil profile. Additional soil tests over time and performance of an infiltration ring study may give more conclusive answers in the future

Feasibility of Bedded Hoop Barns for Market Beef Cattle in Iowa: Cattle Performance, Bedding Use, and Environment

The objective was to document a bedded hoop barn for feeding market beef cattle. A comparison between a bedded hoop barn (15.2 × 36.6 m) and an open-front feedlot building (11.0 × 61.0 m) was conducted in southwest Iowa. The hoop barn was oriented north-south on a ridge with no windbreak. In summer, temperature was relatively consistent between the structures and ambient conditions, although the north end of the hoop barn had a slightly elevated dew point temperature. A summer temperature-humidity index showed that the hoop barn had fewer hours in alert category than either open front or ambient conditions. In winter, a cold stress index showed that the open-front barn provided the most shelter for the cattle with 92% of the hours classified as no impact, compared with the hoop barn at 77% and ambient at 51%. Both ends of the hoop barn were open, except for piled big round bales for a windbreak during winter. Growth, feed-to-gain, and dry matter intake for the cattle were similar between housing systems. Quality and yield grades were similar. Mud scores may be less for cattle from the bedded hoop barn compared with the open-front feedlot where mud was possible. Labor usage was similar for the hoop barn and the open-front feedlot. Labor occurred throughout the feeding period for the hoop barn because manure cleaning occurred weekly. Bedded hoop barns offer a viable alternative for feeding beef cattle and may reduce feedlot runoff

The Effects of Bedding Pack Clean-out in Hoop Barns for Feedlot Cattle

Bedded hoop barns have become popular for feeding beef cattle. The cattle are kept in the hoop barn, which is bedded to form a manure pack. ISU work has shown that the cattle perform well. However, producers question how to manage the pack and when to clean out. The objective of this study was to compare three clean-out strategies (none, once, and twice) for beef cattle fed in hoop barns

Beef Cattle Feeding in a Deep-Bedded Hoop Barn: Year Two

A three-year study evaluating the performance of yearling steers in a deep-bedded hoop barn has completed the second year. A 50 × 120 foot hoop barn was constructed at the ISU Armstrong Research Farm in the late fall of 2004. The comparison feedlot is an outside lot with shelter that includes a drive-through feed alley. Two groups of yearling steers were fed each year. The summer/fall groups were put on test in August and marketed in November. The winter/spring groups were put on test in December and marketed in two drafts in April/May. Overall the cattle performed similarly with similar carcass data for both housing systems. The information presented is for two years of a three-year study. The cattle had a lower mud score in the hoop barn, particularly for the winter/spring feeding periods. As expected the deep-bedded hoop system used more bedding than the semi-confinement lots. The bedded hoop barn required about 5 to 6 lb of cornstalk bedding per head per day that the steers were on feed

Effects of Stocking Density on Steer Performance and Carcass Characteristics in Bedded Hoop and Open Front Confinement Facilities: Progress Report

Interest in feeding cattle in bedded confinement facilities has grown in part due to increased regulations regarding open feedlot runoff. Work in Iowa has documented that cattle confined in a bedded hoop barn perform similarly to cattle fed in an open feedlot with shelter. The work was done with a stocking density of 50 sq ft per steer in the bedded hoop barn. A hoop barn is a more expensive facility system compared with open lot configurations. Fixed costs (facilities) are partially determined by stocking density. The objective of this study was to determine the effects of increased stocking density on performance and carcass characteristics of steers fed in bedded hoop and bedded open front facilities. The trials were conducted in 2008 and 2009 at the ISU Armstrong Research Farm, Lewis, IA. The hoop barn was stocked with 40, 45, and 50 head per pen resulting in 50, 45, and 40 sq ft per steer, respectively. In the open front cattle feeding facility, pens were constructed to confine the cattle on concrete with bedding. Again the stocking density was 50, 45, and 40 sq ft per steer. In all trials, there was one stocking density per housing type per trial. The diet fed was 45.0% dry corn, 14.8% ground hay, 36.8% modified distillers grains, and 3.4% supplement on an as fed basis. The total diet was approximately 69% dry matter. Because the project is on going, no statistical analysis was performed. However, the cattle performance and carcass characteristics seemed to be similar across all facilities and stocking densities. There may be a trend for slightly less average daily gain for the highest stocking densities (6% less in the hoop and 3% less in the open front). Bunk space may be a factor in cattle performance as well as density. However, without more replications and statistical analysis, no conclusions can be made at this time

Beef Cattle Feeding in a Deep-Bedded Hoop Barn: Year One

A three-year study evaluating the performance of yearling steers in a deep-bedded hoop barn has completed the first year. A 50 × 120 foot hoop barn was constructed at the ISU Armstrong Research Farm in the late fall of 2004. The comparison feedlot is an outside lot with shelter that includes a drive-through feed alley. For the first year of the three-year study, two groups of yearling steers were fed. The first group (Group 1) was put on test August 5, 2005 and marketed on November 15, 2005 for a summer/fall feeding period. The second group (Group 2) was put on test December 21, 2005 and marketed in two drafts on April 4, 2006 and May 10, 2006 for a winter/spring feeding period. Overall the cattle performed similarly with similar carcass data for both housing systems. The information presented is the first year of a three-year study. The cattle had a lower mud score in the hoop barn, particularly for the winter/spring feeding period. As expected the deep-bedded hoop system used more bedding than the semi-confinement lots. The bedded hoop barn required about 5 to 6 lb of cornstalk bedding per head per day that the steers were on feed

Beef Cattle Feeding in a Deep Bedded Hoop Barn: A Preliminary Study

A deep bedded hoop confinement building was constructed at the ISU Armstrong Research Farm in Southwest Iowa in 2004. The building consists of three pens. Shortly after the completion of construction a preliminary study was initiated to compare performance, carcass characteristics, and bedding and labor use to that of a conventional semi-confinement system. The cattle used in this study were steer and heifer calves from the ISU McNay Research Farm. Performance and carcass measurements appeared similar comparing the two systems. However, the hoop building cattle used more bedding and appeared to have lower mud scores. Labor use may have favored the hoop building compared to the conventional system. In 2005, a three year study was initiated to compare the systems with yearling steers. Two turns of yearling cattle will be fed each year, one in summer and one in winter