Feedlot Placement Research Articles

Auction market placement and a rest stop during transportation affect the respiratory bacterial microbiota of beef cattle.

Bovine respiratory disease (BRD) is a significant health problem in beef cattle production, resulting in considerable economic losses due to mortalities, cost of treatment, and reduced feed efficiency. The onset of BRD is multifactorial, with numerous stressors being implicated, including transportation from farms to feedlots. In relation to animal welfare, regulations or practices may require mandatory rest times during transportation. Despite this, there is limited information on how transportation and rest stops affect the respiratory microbiota. This study evaluated the effect of cattle source (ranch-direct or auction market-derived) and rest stop duration (0 or 8 h of rest) on the upper respiratory tract microbiota and its relationship to stress response indicators (blood cortisol and haptoglobin) of recently weaned cattle transported for 36 h. The community structure of bacteria was altered by feedlot placement. When cattle were off-loaded for a rest, several key bacterial genera associated with BRD (Mannheimia, Histophilus, Pasteurella) were increased for most sampling times after feedlot placement for the ranch-direct cattle group, compared to animals given no rest stop. Similarly, more sampling time points had elevated levels of BRD-associated genera when auction market cattle were compared to ranch-direct. When evaluated across time and treatments several genera including Mannheimia, Moraxella, Streptococcus and Corynebacterium were positively correlated with blood cortisol concentrations. This is the first study to assess the effect of rest during transportation and cattle source on the respiratory microbiota in weaned beef calves. The results suggest that rest stops and auction market placement may be risk factors for BRD, based solely on increased abundance of BRD-associated genera in the upper respiratory tract. However, it was not possible to link these microbiota to disease outcome, due to low incidence of BRD in the study populations. Larger scale studies are needed to further define how transportation variables impact cattle health.

Comparison of pathogenic bacteria in the upper and lower respiratory tracts of cattle either directly transported to a feedlot or co-mingled at auction markets prior to feedlot placement.

Bacterial bronchopneumonia (BP) has been associated with purchasing cattle through auction markets. However, whether auction markets are a source of BP-associated bacterial pathogens is unknown. This study evaluated prevalence, antimicrobial susceptibility, and genetic relatedness (using pulsed-field gel electrophoresis, PFGE) of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni isolated from cattle either transported to an auction market prior to feedlot placement (AUC), or directly to a feedlot from a farm (RANC). Two groups of cattle were enrolled (N = 30 per group) from two separate farms with 15 animals from an individual farm designated as AUC or RANC. Deep nasal swab (DNS) and trans-tracheal aspirates (TTA) were collected on day 0 at weaning (T0) and on day 2 at on-arrival processing at the feedlot (T1). The DNS were also collected on day 9 (T2) and day 30 (T3) after arrival at the feedlot. In both TTA and DNS, prevalence of bacteria did not differ between AUC and RANC groups (P > 0.05). None of the bacteria isolated at T0 were resistant to antimicrobials and diversity of all bacteria was greatest at T0 and T1. In Group 1 cattle, 100% of P. multocida isolated at T2 and T3 were multi-drug resistant. These isolates were highly related (>90%) according to PFGE, with most being clones. Though limited in size, results for animals evaluated in this study suggested that auction markets were not a major source of resistant BP pathogens, however, horizontal transmission of a multi-resistant strain of P. multocida occurred in a feedlot. Spread of resistant P. multocida was likely due to the selective pressures imposed by feedlot antimicrobial use and encoded resistance by the bacteria.

Temporal Changes in the Faecal Microbiota of Beef Cattle on Feedlot Placement.

Simple SummaryMicroorganisms inhabiting the gut influence the health and productivity of livestock. Studies in ruminants including beef cattle show that ruminal microorganisms can help convert poor-quality or indigestible feed into nutrients, thereby influencing economically important traits like feed conversion efficiency and meat quality (e.g., marbling), and also interact with receptors on intestinal epithelial cells to regulate a variety of physiological processes including immune responses. Studies have also shown that the proportions of different groups of microorganisms in the gut are influenced by exposure to stress. In beef cattle, given that most cattle are finished on feedlots, induction into feedlots can expose cattle to stress due to transportation, change in diet and change in the handling and management of animals. Therefore, the primary objective of this study was to characterise how gut microorganisms change over time when cattle are inducted into feedlots. The results indicate that there are significant changes in the profiles of gut microorganisms in cattle that are visible soon after feedlot placement. These changes primarily include a reduced diversity of microorganisms within the gut of individual cattle and increased differences in the types of microorganisms that inhabit the gut of different cattle.The microbial communities that inhabit the intestinal tract play an important role in modulating health and productivity. Environmental stressors can impact microbial communities, which can significantly influence host physiology. Cattle are subjected to several environmental stressors when placed on feedlots, such as transportation stress, exposure to feedlot environments and change in diet and management. Exposure to these stressors could influence host gut microbiota, which in turn, could potentially influence host health and performance. The aim of the current study was to characterise the temporal changes that occur in intestinal microbiota as a consequence of feedlot placement by profiling 16s rRNA sequences in rectal faecal samples. When faecal microbiome profiles were compared in terms of relative abundances and alpha diversity metrics, the results showed significant, observable changes in profiles 2 days post-feedlot induction. Furthermore, beta-diversity analysis indicated that the phylogenetic similarity between samples significantly decreased on day 2 (PERMANOVA, p < 0.001). These trends were suggestive of a short-term reduction in microbial diversity coupled with decreased similarity between animals. These changes warrant further investigation and could provide opportunities for improved performance, health and even welfare of feedlot cattle in future.

Effect of placement weight and days on feed on feedlot cattle performance and carcass traits

One hundred and thirty six Angus steers were used to evaluate the effects of feedlot placement weight (PW; weight of the animal at the time of its placement into the feedlot) and days on feed (DOF) on feed efficiency, carcass transfer (CT), and carcass traits. The 2 × 4 factorial experiment included PW (Light (LT), 310 kg BW; or Heavy (HV), 415 kg BW) and DOF (54, 83, 111, or 145 d) before slaughtering. At d 0, four steers selected at random from each PW group were slaughtered to determine initial hot carcass weight (HCW). The rest of the steers were allocated in pens (4 pens/treatment; 4 steers/pen) with ad libitum access to feed and drinking water. No PW × DOF interactions were detected for any response variables (P > 0.05). Heavy steers showed greater (P < 0.001) daily dry matter intake (DMI) than LT steers. Daily DMI did not change (P = 0.11) across DOF. Average daily gain (ADG) and daily carcass weight gain (CWG) were not affected (P > 0.05) by PW. Although ADG showed a quadratic (P = 0.003) response across DOF, CWG was higher (P < 0.05) for steers fed 83 d or longer. This resulted in a linear increase (P < 0.001) in CT (ratio of CWG to ADG, expressed as a percentage) during the 145 feeding period. Feed efficiency (DMI: ADG and DMI: CWG ratios) was better (P < 0.001) for LT than HV steers. The ratio DMI: ADG was higher (P < 0.05) for 145 DOF steers, whereas the ratio DMI: CWG tended (P = 0.08) to be better for 111 DOF. Heavy steers showed greater (P < 0.05) final live weight, HCW, ribeye area, subcutaneous fat thickness, and marbling score than LT steers. Final weight and HCW increased linearly (P < 0.001) with DOF. Subcutaneous fat thickness was higher (P < 0.05) for steers fed 111 d or longer. Marbling score and LM total lipid increased linearly (P < 0.001) with DOF. Longissimus muscle pH and color (a*, b*), and subcutaneous fat color (L*, a*, b*) were not affected (P > 0.05) by treatments. Warner Bratzler shear force did not differ (P = 0.16) between PW but was affected (P = 0.005) by DOF. However, all steaks showed a WBS value below 4.0 kg. Regardless of treatment, WBS decreased (P < 0.001) as postmortem aging days increased. Overall, HV steers produced larger carcasses that had greater fat deposition, and similar tenderness than LT steers. Feeding up to 111 days, regardless PW, could improve animal performance and CT, and produce large carcasses with acceptable levels of subcutaneous fat thickness and palatable beef.

Evaluation of the Nasopharyngeal Microbiota in Beef Cattle Transported to a Feedlot, With a Focus on Lactic Acid-Producing Bacteria.

The nasopharyngeal (NP) microbiota is important in defining respiratory health in feedlot cattle, with certain NP commensals potentially protecting against bovine respiratory disease (BRD) pathogens. In the present study, we evaluated longitudinal changes in the NP microbiota with a focus on lactic acid-producing bacteria (LAB) and their linkage with BRD-associated bacteria in steers (n = 13) that were first transported to an auction market, and then to a feedlot. Deep nasopharyngeal swabs were collected at the farm before transportation to the auction market (day 0), at feedlot placement (day 2), and 5 (day 7) and 12 (day 14) days after feedlot placement. Swabs were processed for the assessment of the NP microbiota using 16S rRNA gene sequencing, and for the detection of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni by culturing. Possible associations among the top 15 most relatively abundant bacterial genera were predicted using a stepwise-selected generalized linear mixed model. Correlations between LAB and BRD-associated Pasteurellaceae families were also assessed. In addition, antimicrobial activity of selected LAB isolates against M. haemolytica was evaluated in vitro. A noticeable shift was observed in the NP microbial community structure, and in the relative abundance of LAB families as a result of auction market exposure, transport and feedlot placement. Varying degrees of positive or negative associations between the 15 most relatively abundant genera were observed. Many of the LAB families were inversely correlated with the BRD-associated Pasteurellaceae family as the cattle were transported to the auction market and then to the feedlot. Nearly all steers were culture-negative for M. haemolytica and H. somni, and P. multocida became less prevalent after feedlot placement. Isolates from the Lactobacillaceae, Streptococcaceae, and Enterococcaceae families inhibited the growth of M. haemolytica. The results of this study indicated that the NP microbiota became more diverse with an increase in microbial richness following transport to an auction market and feedlot. This study provides evidence of potential cooperation and exclusion taking place in the respiratory microbial community of cattle which may be useful for developing microbial-based strategies to mitigate BRD.

Antibiotic treatment in feedlot cattle: a longitudinal study of the effect of oxytetracycline and tulathromycin on the fecal and nasopharyngeal microbiota

BackgroundBeef cattle in North America frequently receive an antibiotic injection after feedlot placement to control and manage bovine respiratory disease. The potential collateral effect of these antibiotics on the bovine microbiome is largely unknown. Therefore, we determined the longitudinal impact of two commonly administered veterinary antibiotics, oxytetracycline and tulathromycin, on the fecal and nasopharyngeal (NP) microbiota of beef cattle that were transported to a feedlot. We also report the effect these antibiotics have on several antibiotic resistance determinants in both the fecal and NP microbiome.ResultsOxytetracycline and tulathromycin perturbation of the bovine fecal and NP microbiota was greatest at days 2 and 5. Although the NP microbiota of the tulathromycin-treated cattle had recovered by day 12, the NP microbiota of the oxytetracycline-treated group remained altered through day 34. Overall, the NP microbiota appeared to be more sensitive to antibiotic treatment than the fecal microbiota. Members of the bacterial Microbacteriaceae family were most notably affected by antibiotic administration in the NP microbiota. Both antibiotics protected against Pasteurella spp. in the nasopharynx at days 2 and 5. Despite very similar diets at both locations, the largest shift in the fecal and NP microbiota occurred after transport to the feedlot (P < 0.05). Antibiotic resistance determinants in the NP microbiome were also affected more strongly by antibiotic treatment than those in the fecal microbiome. Oxytetracycline increased the proportion of erm(X), sul2, tet(H), tet(M), and tet(W) in NP samples and tet(M) and tet(W) in fecal samples, at day 12 (P < 0.05). The effect of tulathromycin on the relative abundance of resistance genes in the NP microbiome was greatest at day 34 as erm(X), sul2, and tet(M) were enriched (P < 0.05).ConclusionsAdministration of a single injection of oxytetracycline and tulathromycin resulted in significant changes in the NP and fecal microbiota during the first 5 days after treatment. Antibiotic treatment also increased the relative abundance of several antibiotic resistance determinants in the fecal and NP microbiome at either day 12 or 34.

Injectable antimicrobials in commercial feedlot cattle and their effect on the nasopharyngeal microbiota and antimicrobial resistance

Beef cattle in North America that are deemed to be at high risk of developing bovine respiratory disease (BRD) are frequently administered a metaphylactic antibiotic injection to control the disease. Cattle may also receive in-feed antimicrobials to prevent specific diseases and ionophores to improve growth and feed efficiency. Presently, attempts to evaluate the effects that these medications have on antibiotic resistance in the bovine nasopharyngeal microbiota have been focused on culturable bacteria that are associated with BRD. Therefore, we assessed the effects of injectable antibiotics on the nasopharyngeal microbiota of commercial feedlot cattle in Alberta, Canada, through the first 60 d on feed. Although all cattle in the study were also receiving in-feed chlortetracycline and monensin, the administration of a single injection of either oxytetracycline or tulathromycin at feedlot placement altered the nasopharyngeal microbiota in comparison with the cattle receiving only in-feed antibiotics. Oxytetracycline significantly (P < 0.05) reduced the relative abundance of Mannheimia spp. from feedlot entry to exit (≥60 d) and both oxytetracycline and tulathromycin treated cattle had a significantly lower relative abundance of Mycoplasma spp. at feedlot exit compared with the in-feed antibiotic only group. The proportion of the tetracycline resistance gene tet(H) was significantly increased following oxytetracycline injection (P < 0.05). Oxytetracycline also reduced both the number of OTUs and the Shannon diversity index in the nasopharyngeal microbiota (P < 0.05). These results demonstrate that in feedlot cattle receiving subtherapeutic in-feed antimicrobials, the administration of a single injection of either oxytetracycline or tulathromycin resulted in measurable changes to the nasopharyngeal microbiota during the first 60 d following feedlot placement.

The nasopharyngeal microbiota of beef cattle before and after transport to a feedlot

BackgroundThe nasopharyngeal (NP) microbiota plays an important role in bovine health, comprising a rich and diverse microbial community. The nasopharynx is also the niche for potentially pathogenic agents which are associated with bovine respiratory disease (BRD), a serious and costly illness in feedlot cattle. We used 14 beef heifers from a closed and disease-free herd to assess the dynamics of the NP microbiota of cattle that are transported to a feedlot. Cattle were sampled prior to transport to the feedlot (day 0) and at days 2, 7, and 14.ResultsThe structure of the NP microbiota changed significantly over the course of the study, with the largest shift occurring between day 0 (prior to transport) and day 2 (P < 0.001). Phylogenetic diversity and richness increased following feedlot placement (day 2; P < 0.05). The genera Pasteurella, Bacillus, and Proteus were enriched at day 0, Streptococcus and Acinetobacter at day 2, Bifidobacterium at day 7, and Mycoplasma at day 14. The functional potential of the NP microbiota was assessed using PICRUSt, revealing that replication and repair, as well as translation pathways, were more relatively abundant in day 14 samples. These differences were driven mostly by Mycoplasma. Although eight cattle were culture-positive for the BRD-associated bacterium Pasteurella multocida at one or more sampling times, none were culture-positive for Mannheimia haemolytica or Histophilus somni.ConclusionsThis study investigated the effect that feedlot placement has on the NP microbiota of beef cattle over a 14-d period. Within two days of transport to the feedlot, the NP microbiota changed significantly, increasing in both phylogenetic diversity and richness. These results demonstrate that there is an abrupt shift in the NP microbiota of cattle after transportation to a feedlot. This may have importance for understanding why cattle are most susceptible to BRD after feedlot placement.

Effects of number of viral respiratory disease vaccinations during preconditioning on health, performance, and carcass merit of ranch-direct beef calves during receiving and finishing

Angus × Hereford calves (n = 430; initial BW = 230 ± 32 kg) were stratified by sex, age, and BW and assigned randomly to receive 0, 1, 2, or 3 doses of modified-live respiratory disease (BRD) vaccine before feedlot placement (0X, 1X, 2X, or 3X, respectively). Calves from 2 sources were weaned 29 d before feedlot placement and placed in a weaning facility at each ranch of origin. Initial BRD vaccination occurred at weaning, and calves were revaccinated according to treatment assignments at 14-d intervals. There were no differences (P = 0.49) in the incidence of morbidity during the 29-d weaning period among treatments (11.6, 5.2, 7.4, and 5.3% incidence for 0X, 1X, 2X, and 3X, respectively). Calf ADG, DMI, and G:F during weaning were not different (P ≥ 0.56) among treatments. Calf BW and ADG were similar (P ≥ 0.54) among treatments at 27 d after receiving and 55 d after receiving. Degree of BRD vaccination had no effect (P ≥ 0.59) on DMI or G:F during receiving. Incidence of morbidity was not different (P = 0.66) among treatments during receiving. Finishing ADG, DMI, G:F, days on feed, and final BW were not different (P ≥ 0.62) among treatments. Likewise, marbling score, USDA YG, LM area, and KPH were not different (P ≥ 0.07) among treatments. Vaccination regimens did not affect (P ≥ 0.70) incidence of liver abscesses or lung lesions. Vaccination for BRD before feedlot placement did not affect receiving performance, finishing performance, or carcass characteristics of calves preconditioned on the ranch of origin.

Effects of weaning-period length on growth and health of preconditioned, spring-born beef calves originating from the Great Plains. II. Early weaning

Angus × Hereford calves (n = 409; initial BW = 163 ± 31 kg) were weaned early (~ 130 d of age) and assigned randomly to treatments that corresponded to a length of time (d) between separation from their dam and transport to a feedlot: 0 (i.e., nonweaned), 15, 30, 45, or 60 d. Weaning date varied by treatment; transport occurred on a common date and at a common age (160 ± 19 d) for all treatments. Calves were vaccinated against common diseases 14 d before maternal separation and again on the day of maternal separation. Calves were transported < 20 km to a ranch-of-origin weaning facility following separation from dams and penned according to treatment. Calves were fed a complete diet (16.9% CP, 1.21 Mcal of NEg/kg) ad libitum. On a common date, all calves were transported 4 h to a commercial auction market and held for 14 h. They were transported subsequently 1 h to a feedlot. Calf BW at transport was not different between weaned and nonweaned calves (P = 0.13) but decreased linearly (P = 0.01) as the length of the ranch-of-origin weaning period increased. Pre-transport morbidity increased linearly (P = 0.05) as length of the weaning period increased. Calves not weaned before feedlot placement tended to have lesser (P = 0.08) ADG during receiving than weaned calves; moreover, ADG increased linearly (P = 0.02) as length of the ranch-of-origin weaning period increased. There were no treatment differences (P ≥ 0.24) in morbidity during receiving. In addition, finishing ADG, days on feed, slaughter BW, and carcass characteristics were not different (P ≥ 0.11) between weaned and nonweaned calves. Cow BCS change from 60 d before to 60 d after transport of calves increased linearly (P = 0.01) as weaning-period length increased. Cows with calves assigned to the 0-d pretransport weaning treatment had lesser (P = 0.03) pregnancy rates than cows with calves weaned before transport; moreover, pregnancy rate increased linearly (P = 0.03) with successively earlier weaning dates. Under the conditions of this experiment, ranch-of-origin weaning periods ≥ 15 d improved ADG of early-weaned calves during feedlot receiving but had minimal effects on health, finishing performance, or carcass characteristics.

Comparison of Two Weaning Dates and Two Finishing Systems on Feedlot Performance, Carcass Characteristics, and Enterprise Profitability of Fall-born Steers

ABSTRACT In a 3-yr study, 139 fall-born steers (Angus and Angus x Charolais; BW = 287 ± 31 kg in mid-April) were allotted to 1 of 4 treatments in a 2 x 2 factorial arrangement. Weaning date treatments were 1) mid-April at 212 ± 12 d of age (normal weaning; NW) and 2) mid-July at 300 ± 15 d of age (late weaning). Finishing system treatments were feedlot placement in 1) July, with a mean calf age of 310 ± 14 d (calf-fed; CF), and 2) October, with a mean calf age of 394 ± 15 d (yearling-fed; YF). Steers assigned to the NW treatment were returned to native tall grass prairie rangeland after weaning each year. Steers assigned to the YF treatment grazed abundant native tall grass prairie pasture for an additional 84-d period. The number of days on feed was greater (P 0.05) for time of weaning were detected, nor were there any interactions (P > 0.05) between weaning and finishing system. Yearling-fed steers were heavier (34 kg; P 0.05) were detected for any carcass traits measured. System economic analysis showed no differences in break-even selling price or system profitability.

Phase Feeding Strategies To Meet Metabolizable Amino Acid Requirements of Calf-Fed Holstein Steers

ABSTRACT One hundred eight Holstein steer calves (114 ± 8 kg) were used to evaluate effects of phase feeding metabolizable amino acids (MAA) on growth performance and carcass characteristics. Three feeding strategies were evaluated: 1) control, single-phase feeding (steers were fed a single urea-based growing-finishing diet that meets the average MAA requirements for the overall feeding period); 2) 2-phase feeding (steers were fed a diet formulated to meet the average MAA requirements for the first 112 d on feed, and thereafter finished on the control urea-based diet); and 3) 3-phase feeding (2 diets were formulated to meet average MAA requirements during the first and second 56-d feedlot feeding periods, and thereafter cattle were finished on the control urea-based diet). Two-phase feeding and 3-phase feeding management strategies produced similar (P > 0.20) growth performance. Multiple-phase feeding increased ADG (18%, P 0.20) on growth performance; however, multiple-phase feeding increased overall (351-d) ADG (6.3%, P 0.20) of 3-phase vs. 2-phase feeding strategies on carcass characteristics. Multiple-phase feeding increased hot carcass weight (5.2%, P g was similar (96%) to that expected for the 2- and 3-phase programs during the first 112 d, but was only 83% of expected for the single-phase program. It was concluded that a 2-phase feeding program was needed to improve overall ADG, G:F, and energetic efficiency of calf-fed (placed in the feedlot as lightweight calf) Holstein steers compared with a conventional single-phase system. At a minimum, a 2-phase system would need to separately consider MAA requirements from feedlot placement to 280 kg BW (phase 1) and from 280 kg BW to harvest (phase 2). Methionine, Lys, and His appear to be the first limiting amino acids during the first feeding phase. During the second phase (280 kg to harvest), supply of all MAA acids will exceed requirements, even where urea is the sole source of supplemental N. Maximizing growth rate during the first feeding phase may enhance carcass dressing percent and LM area.

Effects of early weaning on performance of cow/calf pairs (2004)

Commercial cow/calf pairs (Angus based, n=103) were used to determine the effect of calf weaning age on cow body weight and body condition score (scale=1 to 9) and calf performance in terms of subcutaneous fat and marbling deposition. Only cows with male progeny (steers, n=52; bulls, n=51) were used in this study. Treatments were: 1) early-weaned bulls, 2) early-weaned steers, 3) traditionally weaned bulls, and 4) traditionally weaned steers. Cow/calf pairs grazed pastures at four different locations. Calving began February 1, 2003, and ended in early April. In the early-weaned treatment group, calves were weaned June 25, with an average age of 115 days. In the late-weaned treatment group, calves were weaned October 6, with an average age of 218 days. The data indicate that the cows in the early-weaned treatment group gained 121 lb more weight (P<0.0001), had 0.13 inches more external backfat (P<0.0001), and had an average body condition score 1.2 greater (P<.0001) than their late-weaned counterparts. All steer calves were implanted before they entered the feedlot. Early weaning and subsequent feedlot placement produced heavier calves at approximately nine months of age. Ultrasound technology indicated that early-weaned calves had greater backfat and marbling scores 26 days after feedlot placement than did traditionally weaned calves. However, the early-weaned bulls had less backfat at a similar average weight to their steer contemporaries.

Effect of age at feedlot entry on performance and carcass characteristics of bulls and steers1

Seventy Angus × Simmental calves (BW = 166.3 ± 4.2 kg) were used in a 3 × 2 factorial arrangement to determine the effect of age at feedlot entry and castration on growth, performance, and carcass characteristics. At 82 d of age, steers were castrated. Calves were placed in the feedlot at 111 (early-weaned), 202, or 371 (yearling) d of age. Steers were implanted with Synovex-S followed 93 d later with Revalor-S. Calves were harvested on an individual basis when fat thickness was estimated to be 1.27 cm. During the feedlot phase, yearlings gained faster (P < 0.01) than calves placed in the feedlot at 202 or 111 d of age (1.88, 1.68, and 1.62 kg/d, respectively); however, from 111 d of age until harvest, ADG was greatest for early-weaned calves, intermediate for cattle placed in the feedlot at 202 d of age, and lowest for yearlings (1.62, 1.47, and 1.21 kg/d, respectively; P < 0.01). Early-weaned calves spent the most days in the feedlot, followed by calves placed in the feedlot at 202 d of age; yearlings spent the fewest days in the feedlot (221, 190, and 163 d, respectively; P < 0.01). Total DMI when in the feedlot was similar (P = 0.22) among age groups; however, daily DMI was lowest for early-weaned calves, intermediate for calves placed in the feedlot at 202 d of age, and the highest for yearlings (7.1, 8.1, 10.5 kg/d, respectively; P < 0.01). Early-weaned calves were the most efficient, followed by calves placed in the feedlot at 202 d of age; yearlings were the least efficient (227, 207, 180 g gain/kg feed, respectively; P < 0.01). Weight at harvest (682, 582, 517 kg, respectively; P < 0.01) and hot carcass weight (413, 358, 314 kg, respectively; P < 0.01) were greatest for yearlings, intermediate for cattle placed in the feedlot at 202 d of age, and lowest for early-weaned calves. Early-weaned calves had the smallest longissimus area, followed by calves placed in the feedlot at 202 d of age; yearlings had the largest longissimus area (77, 86, 88 cm2, respectively; P < 0.01). Calves placed in the feedlot at 111 and 202 d of age had lower yield grades (3.2, 3.1, 3.5, respectively; P < 0.04), and produced fewer select carcasses than yearlings (25, 13, 48%, respectively; P < 0.01). Bulls and implanted steers both had an ADG of 1.7 kg/d when in the feedlot; however, bulls had a greater (P < 0.09) hot carcass weight (370 vs 354 kg) and a larger (P < 0.01) longissimus area (85.8 vs 81.3 cm2) than steers. Earlier feedlot placement resulted in greater quality grades but lower carcass weights.

Predicting the Value of Feeder Cattle Placed into an Accelerated Finishing Program Under Dynamic Market Conditions

Data from 769 steer calves that were fed as part of the South Dakota Retained Ownership Demonstration program were used for this study. At feedlot placement, initial weight, hip height, fat thickness, age, sire breed, and dam breed were recorded. Calves that were creep fed, vaccinated, and weaned prior to feedlot arrival were identified. Initial pay weight, initial fat thickness, prefeedlot arrival vaccination, Hereford, Angus, or Simmental sires, and intermediate or high milk dams accounted for only 17.16% of the variation in fall calf value as determined by feedlot gain and carcass merit. When using multiple regression techniques to predict value, including year, average daily gain, dressing percentage, and quality grade improved R2 to .8275. Initial variables accounted for only 8.22% of the variation in gain, 14.28% of the variation in dressing percentage, and 16.36% of the variation in percentage choice. Initial variables evaluated in this study are of limited value in predicting feeder calf value under dynamic market conditions.

Economic Analysis of Grazing and Subsequent Feeding of Steers from Three Fescue Pasture Alternatives

Cattle grazing tall fescue (Festuca arundinacea Schreb.) infected with the endophytic fungus, Acremonium coenophialum, typically experience toxicity symptoms, resulting in poor animal performance. However, potential exists for compensatory gains during subsequent finishing. This study provides an economic analysis of three grazing alternatives along with subsequent feedlot performance. The pasture alternatives were endophyte-infected »Kentucky 31« tall fescue (IF); IF interseeded with ladino clover (Trifolium repens L., IFL); and endophyte-free »Missouri 96« tall fescue (MO). Three years of agronomic data from pastures and animal performance data from steers (Bos taurus) were collected

Seasonal performance of finishing heifers (1991)

This study examined the impact of date of feedlot placement on feed conversion, daily gain, and death loss. Results indicated that heifers placed on feed from September to December required more feed per pound of gain, had lower daily gains and higher death loss, and generally exhibited more variation in feeding performance than heifers placed during the rest of the year. Cattle feeders should take these performance variations into account when developing budgets and calculating breakeven sale prices for heifers.

Bermudagrass, Tall Fescue, and Orchardgrass Pasture Combinations with Clover or N Fertilization for Grazing Steers. I. Forage Growth and Consumption, and Animal Performance1,2

AbstractInformation on pasture productivity and forage quality of various adapted species and combinations that support rapid animal gains is needed for successfully backgrounding yearling steers in the humid southeastern USA prior to feedlot placement. To evaluate productivity and quality of pasture combinations for growing beef steers, a grazing experiment was conducted near Memphis, Tenn., in 1975 to 1977 on a Typic Hapludalf. The 1.2 ha pastures were Midland (Cynodon dactylon (L.) Pers.) + (Trifolium repens L.) clover, Midland + N, 1/3 Midland + N plus 2/3 fescue (Festuca arundinacea Schreb.) + N in separate pastures, Midland overseeded with fescue + N, common (C. dactylon var. dactylon) + N, fescue + clover, and orchardgrass (Dactylis glomerata L.) + clover (OG + clo). Nitrogen was applied at 224 kg ha−1 y−1 on bermudagrass and at 67 kg ha−1 y−1 on fescue. Pastures were grazed using a modified put−and−take system maintaining orchardgrass at 7 to 14 cm high and the other grasses at 5 to 8 cm. Forage growth and consumption were determined by the cage−and−strip method. Yearling steers weighing 230 kg in the spring grazed 123 to 150 days; they were weighed at 21−day intervals and visual estimates of species composition were made at that time. Forage yield was 8.3 t/ha for Midland + fescue and ranged between 4.0 and 5.7 t/ha for the other treatments. Estimated forage consumption was 80% or more of the forage growth. Forage crude protein (122 to 152 g/kg) was sufficient for meeting the minimum requirements for growing 250− to 300−kg steers. Stocking rates were between 4 and 6 steers/ha. Average daily gains were about 475 to 575 g for all treatments, except for OG + clo (825 g/day). Pasture productivity ranged between 520 animal grazing days/ha for OG + clo to 1190 for Midland + fescue. The productivity of the other pastures was between 730 and 880 grazing days/ha. Daily forage dry matter (DM) intake was 5 to 7 kg/steer. Steers grazing OG + clo, fescue + clover, and Midland + N pastures had feed efficiencies of about 9 kg DM/kg gain; steers on the other treatments required 11 to 13 kg DM/ kg gain. Beef production was 321, 339, 375, 400, 416, 424, and 593 kg/ha for fescue + clover, common + N, 1/3 Midland − 2/3 fescue, Midland + clover, OG + clo, Midland + N, and Midland + fescue, respectively.