Evaluation of performance and carcass traits for a five-cohort All Heifer, No Cow beef production system demonstration herd.

The All Heifer, No Cow (AHNC) beef production system is an alternative to conventional cow/calf production that involves insemination of nulliparous heifers with sexed semen to produce female calves that are early weaned at 3 mo of age. Dams are finished on a high-concentrate diet and harvested before reaching 30 mo of age. Objectives of this research were to document reproductive, feedyard, calf, and carcass performance of an AHNC herd; evaluate effects of carcass maturity on carcass quality; and determine if performance of initial cohorts (i.e., cohorts 1 and 2) differed from sustaining cohorts (i.e., cohorts 3-5). A total of 272 heifers were enrolled in the AHNC system via five annual cohorts. The system was initiated with 51 yearling, Angus-based heifers, and a replicate set (n = 56) was started 12 mo after. Heifers in cohorts 3 (n = 53), 4 (n = 56), and 5 (n = 56) were primarily offspring of prior cohorts (i.e., cohort 3 heifers born to cohort 1 females), but some were purchased to maintain inventory. Angus replacement heifers were purchased in cohorts 3 (n = 26), 4 (n = 26), and 5 (n = 28). Mean (±standard deviation) pregnancy rate at 30 d after fixed-time artificial insemination (AI) with sexed semen was 50.8% ± 9.4%, and 140-d pregnancy rate was 93.0% ± 1.5%. With AHNC, 61.0% ± 6.5% of females replaced themselves with a heifer. During finishing, average daily gain (ADG) was 1.9 ± 0.4 kg • d-1 and dry matter intake (DMI) was 14.9 ± 1.9 kg • d-1. Hot carcass weight (HCW) was 367 ± 35 kg. The USDA grading system classified 20.5% of all carcasses (n = 220) as C maturity (A00 = 100, B00 = 200, etc.), 62.4% ± 29.1% of carcasses as USDA Choice. USDA yield grade (YG) was 2.6 ± 0.7. Based on cohorts 1 and 2, there were no differences (P = 0.96) in Warner-Bratzler shear force values between A and B maturity vs. C maturity carcasses. Across all cohorts, there were no differences in USDA YG, marbling score (MA), and lean maturity between A and B maturity vs. C maturity carcasses; there were differences in age (P < 0.001), bone maturity (P < 0.001), and overall maturity (P <0.001). A comparison of initial vs. sustaining cohorts showed that initial cohorts had lower (P < 0.001) DMI, heavier (P < 0.001) HCW, and more advanced (P < 0.05) bone maturity. However, there were no differences for 30- and 140-d pregnancy rates, ADG, USDA YG, and MA between initial and sustaining cohorts. The AHNC beef production system can effectively produce female calves and quality carcasses for harvest.

Trace mineral source influences ruminal distribution of copper and zinc and their binding strength to ruminal digesta1,2,3.

Eight crossbred steers (BW 719.0 ± 65.0 kg) with ruminal and duodenal cannulae were used to examine the effect of trace mineral (TM) source on digestibility; ruminal and duodenal solubility of Cu, Zn, and Mn; and in vitro release of Cu, Zn, and Mn from the solid fraction of ruminal digesta. Experiment 1 determined the effect of TM source on DM and NDF digestibility in steers fed a corn silage and steam-flaked corn-based diet. Treatments consisted of 10 mg Cu, 20 mg Mn, and 30 mg Zn/kg DM from either sulfate TM (STM) or hydroxy TM (HTM) sources. Following a 14-d adaptation period, total fecal output was collected for 5 d. Dry matter digestibility was not affected by treatment, but NDF digestibility tended (P < 0.09) to be greater in HTM vs. STM supplemented steers. In Exp. 2, steers were fed a diet without supplemental Cu, Zn, or Mn for 19 d. Steers were then administrated a pulse dose of STM or HTM (2× the National Research Council requirements for Cu, Mn, and Zn) via the rumen fistula. Ruminal and duodenal samples were obtained at 2-h intervals starting at -4 and ending at 24 h relative to dosing. Ruminal soluble Cu and Zn concentrations were affected by treatment, time, and treatment × time. Soluble concentrations and percent soluble Cu and Zn in ruminal digesta increased (P < 0.05) above 0-h values for 10 h following dosing with STM, but not HTM. Concentrations of Cu and Zn in ruminal solid digesta were also affected by treatment, time, and treatment × time. Steers dosed with STM had greater (P < 0.05) solid digesta Cu concentrations at 2 and 4 h but lesser (P < 0.05) concentrations from 6 to 20 h post-dosing than those receiving HTM. Ruminal solid digesta Zn concentrations were greater (P < 0.05) in HTM vs. STM-dosed steers from 6 through 24 h post-dosing. Distribution of Mn in ruminal digesta was affected by TM source, but to a lesser extent than Zn and Cu. Duodenal soluble TM concentrations were variable and not affected by treatment. Binding strength of TM to ruminal solid digesta was estimated at 0, 6, and 12 h post-dosing using dialysis against chelating agents. The percentage of Cu and Zn released from ruminal solid digesta by dialysis against Tris-EDTA was greater (P < 0.05) at 12 h post-dosing from steers receiving HTM vs. STM. Results indicate that Cu and Zn from HTM have low solubility in the rumen and appear to be less tightly bound to ruminal solid digesta than Cu and Zn from STM.

Sensor analysis and initial assessment of detectable first hoof contacts and last break-overs as unique signal fluctuations for equine gait analysis.

The objective of the control study was to assess 2 prominent fluctuations in a single optical signal as being either a true first hoof contact or a last break-over based on descriptive measures. The study builds on initial findings from a preliminary investigation of the embedded-optical-base system's (EOBS) capabilities in signal capturing and feasibility as potential alternative to existing gait technologies, such as piezoelectric (e.g., load cell) systems. Hoof contacts and break-overs were measured (0 to 1 au; arbitrary units) using a 2.4-m (length) × 0.9-m (width) platform containing 1 EOBS. Three mixed-breed horses (n = 3) were injected with saline or either 100 IU or 200 IU Botox (i.e., onabotulinumtoxinA) with a 2.5-mL final volume. Injections were made into the deep digital flexor muscle at the motor end plates, with electromyography and ultrasound guidance. Horses were observed for 3 time points (pre-, post-, and recovery test days) over the span of a 4-mo period. Signal fluctuations [i.e., amplitude of hoof impacts based on true first hoof contacts (ΔS TS) and true last break-overs (ΔS TL)] and kinematics [i.e., complete gait pass (CGP) time duration (T)] were recorded from each horse. Visual observations and video analysis were used for determining gait pattern categories. Individual horse measurements were analyzed for each trial, compared with video data and classified. Comparison of primary signal fluctuations (i.e., ΔS TS vs. ΔS TL; forelimb vs. hindlimb) exhibited significant differences between hoof contacts and break-overs (P < 0.05). Right and left forelimb hoof contacts and hindlimb break-overs were not significantly different (P = 0.966; 0.063 ± 0.135; Estimate ± SE; P = 0.606; 0.176 ± 0.142; Estimate ± SE, respectively). Additionally, treatment vs. saline forelimbs did not exhibit significant difference (P = 0.7407; -0.098 ± 0.279; Estimate ± SE). Overall, data showed that the EOBS can collect repeatable and unique primary signal fluctuations as prominent and different gait measurements providing evidence to further development and research of the sensing system.

Nitrous Oxide and Ammonia Emissions from Cattle Excreta on Shortgrass Steppe.

Grazing cattle redistribute nitrogen (N) consumed in forage through urine and feces patches. The high concentration of N in these patches often exceeds the uptake demands of the local plant community, thereby providing ideal conditions for losses of reactive N. However, knowledge on nitrous oxide (NO) and ammonia (NH) emissions from excretal patches on shortgrass steppe grassland is limited. We studied the effect of cattle urine (1002 kg N ha) and feces (1021 kg N ha) patches on NO and NH emissions in two sites with contrasting vegetation: (i) cool-season (C3) 'Bozoisky-Select' Russian wildrye [ (Fisch.) Nevski], pasture (C3Past) and (ii) C4-dominated native shortgrass steppe rangeland (C4SS). Nitrous oxide and NH were measured using semi-static and semi-open chambers, respectively. Cumulative NO emissions were 217 and 173% greater and cumulative volatile NH emissions were 339 and 157% greater on C3Past compared with C4SS from the urine and feces treatments, respectively. Nitrous oxide emission factors were 0.20 and 0.05% for urine and 0.07 and 0.03% for feces on C3Past and C4SS, respectively. Our findings suggest that using the IPCC Tier 1 default emission factor (2%, 95% CI = 0.7-6%) to estimate NO emissions from cattle excretal patches on shortgrass steppe grassland would result in a significant overestimation for these dryland systems. Ammonia emission factors were 35 and 10% for urine and 7 and 5% for feces on C3Past and C4SS, respectively. With the exception of the urine treatment on C3Past, observed NH emissions were consistent with the IPCC Tier 1 default assumption that 20% (95% CI = 5-50%) of excretal N is volatilized as NH+NO.

A comparison of supplemental calcium soap of palm fatty acids versus tallow in a corn-based finishing diet for feedlot steers.

Rumen bypass fat is commonly added to increase energy intake in dairy cattle. The objective of this study is to examine the addition of rumen bypass fat during finishing period on performance and carcass characteristics in grain fed steers. This study was conducted as a completely randomized block design with 126 cross-bred steer calves (initial BW 471.5 ± 7.5 kg) randomly assigned to pens with 9 steers/pen (n = 7 pens/treatment). Each pen was randomly assigned to one of two treatment groups; rumen bypass fat treatment (CCS, calcium soap of palm fatty acids) and control diet (CT, tallow). The diets were formulated to be isonitrogenous and isocaloric. Animals were fed twice daily at 110 % of the previous daily ad libitum intake. Blood from each sample was taken from the jugular vein. Muscle and adipose samples were collected from the longissimus dorsi regions. Feedlot performance and carcass characteristics were assessed. To examine adipogenic gene expression, quantitative real-time PCR was completed. Steers fed the CT had a greater level of performance for most of the parameters measured. The CT group had greater DMI (P < 0.05) and tended to have greater ADG (P < 0.10). Marbling score (P < 0.05) and quality grade (P < 0.05) were greater for steers fed the CT diet than those fed CCS. The longissimus muscle area tended to be greater (P < 0.10) in steers fed CT (87.60 cm(2)) than those fed CCS (84.88 cm(2)). The leptin mRNA expression was down-regulated (P < 0.05) in adipose tissue of steers fed a CCS when compared to those fed CT. These data suggest that calcium soap of palm fatty acids can be added to finishing diets without significant reduction in final body weight, although there may be modest reductions in marbling and quality scores.

The modern feedlot for finishing cattle.

The modern beef feedlot has evolved into a complex system that is very dependent upon technology. Modern feedlots are organized into departments, often including the office, cattle, yard, feed milling, and feed departments, that allow for improvements in production efficiency through the specialization of management and labor. Regardless of size, feedlots must succeed at the following tasks: cattle procurement, cattle receiving, cattle processing, daily cattle observations, health treatments, cattle marketing, feed procurement, feed commodity receiving, feed commodity storage, diet formulation, diet delivery, bunk management, and environmental management. Apart from cattle ownership, feedlots create most of their gross income from feed sales, yardage, inventory gain on flaked grain, and combinations of these sources. The future of the industry is filled with economic and political challenges, including high grain prices owing to competition from the ethanol industry, environmental regulations, excess feedlot capacity, and a diminishing labor pool owing to declining rural populations.

Community structures of fecal bacteria in cattle from different animal feeding operations.

The fecal microbiome of cattle plays a critical role not only in animal health and productivity but also in food safety, pathogen shedding, and the performance of fecal pollution detection methods. Unfortunately, most published molecular surveys fail to provide adequate detail about variability in the community structures of fecal bacteria within and across cattle populations. Using massively parallel pyrosequencing of a hypervariable region of the rRNA coding region, we profiled the fecal microbial communities of cattle from six different feeding operations where cattle were subjected to consistent management practices for a minimum of 90 days. We obtained a total of 633,877 high-quality sequences from the fecal samples of 30 adult beef cattle (5 individuals per operation). Sequence-based clustering and taxonomic analyses indicate less variability within a population than between populations. Overall, bacterial community composition correlated significantly with fecal starch concentrations, largely reflected in changes in the Bacteroidetes, Proteobacteria, and Firmicutes populations. In addition, network analysis demonstrated that annotated sequences clustered by management practice and fecal starch concentration, suggesting that the structures of bovine fecal bacterial communities can be dramatically different in different animal feeding operations, even at the phylum and family taxonomic levels, and that the feeding operation is a more important determinant of the cattle microbiome than is the geographic location of the feedlot.

Characterization and identification of hepatic mRNA related to copper metabolism and homeostasis in cattle.

Copper is an essential trace mineral required for growth and development. Copper homeostasis within the cell is mediated by the expression of the Cu transporter protein (CTR1), ATPase7A (ATP7A), ATPase7B (ATP7B), Cox17, and Cu chaperone for Cu-Zn superoxide dismutase (CCS) which helps to regulate Cu uptake, export, and intracellular compartmentalization in non-ruminants. Copper also serves as a cofactor of antioxidant, superoxide dismutase1 (SOD1). Liver tissue from eighteen Holstein bull calves (average BW 201 +/- 58.5 kg, 7.3 +/- 1.9 months) from a previous experiment were utilized to characterize and identify hepatic mRNA related to Cu metabolism and homeostasis in cattle. Hepatic Cu concentration was determined via flame atomic absorption, and total RNA was extracted using TRI reagent and purified using RNeasy. Hepatic Cu concentrations ranged from 86 to 801 mg of Cu/kg DM. Real-time polymerase chain reaction analysis revealed that CTR1, ATP7A, and ATP7B mRNA expressions were negatively correlated with hepatic Cu concentration, while CCS (P = 0.0887) and SOD1 had a tendency (P = 0.0733) to be negatively correlated to hepatic Cu concentration. These data indicate that higher than normal hepatic Cu concentration downregulates gene expression of CTR1, ATP7A, ATP7B, and Cox17, which are involved in bovine liver copper homeostasis.

Dietary supplementation of high levels of saturated and monounsaturated fatty acids to ewes during late gestation reduces thermogenesis in newborn lambs by depressing fatty acid oxidation in perirenal brown adipose tissue.

We hypothesized that dietary supplementation of (n-6) plus (n-3) PUFA during late gestation would increase uncoupling protein-1 (UCP1) gene expression and thereby increase thermogenic capacity of newborn lambs. Thirty twin-bearing ewes were fed rumen-protected fat (2, 4, or 8%) high in saturated and monounsaturated fatty acids (SMFA) or high in (n-6) and (n-3) PUFA. Lambs (n = 7-10 per ewe treatment group) were placed in a cold chamber at 0 degrees C for 2 h. Rectal temperature was higher at birth and increased more with cold exposure in lambs from ewes fed 2 or 4% supplemental fat than in lambs from ewes fed 8% SMFA (fat type x fat level interaction, P = 0.001). Cytochrome c oxidase activity was greatest in brown adipose tissue (BAT) lambs from ewes fed 2% SMFA or 4% PUFA (fat type x fat level interaction, P = 0.01). BAT of lambs from ewes fed 2 or 4% PUFA had nearly 7-fold more (P = 0.05) UCP1 mRNA than BAT of lambs from ewes fed 8% PUFA. UCP1 expression decreased by over 80% by 24 h of age. Supplementation of 8% fat tended to depress palmitate esterification into lipids (P = 0.07) and decreased palmitate oxidation (P = 0.003) in lamb BAT in vitro, especially in those lambs from ewes fed 8% SMFA. Thus, supplementing the diets of ewes with 8% SMFA depressed cold tolerance in newborn lambs, which was reflected in their decreased ability to oxidize fatty acids in vitro.