Corrigendum: Comparative microbiome analysis of beef cattle, the feedyard environment, and airborne particulate matter as a function of probiotic and antibiotic use, and change in pen environment.

[This corrects the article DOI: 10.3389/fmicb.2024.1348171.].

Comparative microbiome analysis of beef cattle, the feedyard environment, and airborne particulate matter as a function of probiotic and antibiotic use, and change in pen environment.

Introduction: Intensive beef cattle production systems are frequently implicated as a source of bacteria that can be transferred to nearby humans and animals via effluent water, manure used as fertilizer, or airborne particulate matter. It is crucial to understand microbial population dynamics due to manure pack desiccation, antibiotic usage, and antibiotic alternatives within beef cattle and their associated feedyard environment. Understanding how bacterial communities change in the presence of antibiotics can also improve management practices for reducing the spread of foodborne bacteria. Methods: In this study, we aimed to compare the microbiomes within cattle feces, the feedyard environment and artificially produced airborne particulate matter as a function of pen change and treatment with tylosin or probiotics. We utilized 16S rRNA sequencing to compare bacterial communities among sample types, study days, and treatment groups. Results: Bacterial community diversity varied as a function of sampling day and pen change (old or new) within fecal and manure pack samples. Manure pack samples from old pens and new pens contained diverse communities of bacteria on days 0 and 84; however, by day 119 of the study these taxonomic differences were less evident. Particulate matter samples exhibited significant differences in community diversity and predominant bacterial taxa compared to the manure pack they originated from. Treatment with tylosin did not meaningfully impact bacterial communities among fecal, environmental, or particulate matter samples; however, minor differences in bacterial community structure were observed in feces from cattle treated with probiotics. Discussion: This study was the first to characterize and compare microbial communities within feces, manure pack, and airborne particulate matter from the same location and as a function of tylosin and probiotic treatment, and pen change. Although fecal and environmental samples are commonly used in research studies and other monitoring programs to infer public health risk of bacteria and antimicrobial resistance determinants from feedyard environments, our study suggests that these samples may not be appropriate to infer public health risk associated with airborne particulate matter.

Effect of feeding method on nutrient utilization and cow performance in limit-fed cow-calf systems.

Delivery of limit-fed, complete rations requires significant capital investment, and creates logistical challenges for producers. Deconstruction and separate delivery of roughage and concentrate portions of diets may decrease feeding cost. Two experiments were conducted to evaluate the potential of separately limit-feeding roughage and concentrate. In Experiment 1, 4 ruminally cannulated steers (371 ± 12 kg bodyweight) were used in a 4 × 4 Latin square to evaluate the effects of time of concentrate delivery in deconstructed diets. Intake was restricted to 80% of predicted NEm requirements of a diet consisting of wheat straw (35%), cracked corn (29%), and distillers' grains (27%) formulated to contain 1.58 Mcal NEm/kg. Treatments were: concentrate fed 2 h prior to wheat straw (-2S), concentrate and wheat straw fed as total mixed ration (TMR), concentrate fed 2 h after wheat straw (+2S), and concentrate fed 12 h after wheat straw (+12S). In Experiment 2, 95 mid- to late-gestation cows (503 ± 151 kg) were used in a 112-d trial to evaluate feeding system on cow performance. Cows were assigned to 1 of 12 pens. Treatments were limit-fed the complete diet from Experiment 1 (TMR), fed roughage and concentrate portions of the deconstructed TMR 12 h apart (SEP), and ad libitum bermudagrass hay (HAY). Bodyweight (BW), BCS, and back fat measures were collected every 28 d. In Experiment 1, treatment did not affect DM or OM digestion (P ≥ 0.88), rate of particulate passage (P ≥ 0.55), or ruminal DM fill (P ≥ 0.19). Fill averaged 3.8 kg DM. Nadir of ruminal pH occurred 4-8 h after concentrate was delivered, but mean ruminal pH was not different among treatments (P = 0.22) ranging from 6.4 to 6.6 for +2S and 12S, respectively. In Experiment 2, treatment did not affect final BW (518 kg; P = 0.72) or final BCS (5.6; P = 0.67), but limit-fed strategies tended (P = 0.06) to have greater final RE (137.1, 98.9, and -14.6 Mcal for TMR, SEP, and HAY, respectively). Delivering forage and concentrate separately did not change digestion, and timing of concentrate delivery had only minor effects on ruminal fermentation. Limit-feeding a TMR or separate delivery of roughage and concentrate sustained cow performance compared to ad libitum hay consumption.

Maternal nutrient restriction alters endocrine pancreas development in fetal heifers.

Maternal nutrient restriction during pregnancy alters fetal programming, which modifies the growth and health of the offspring in postnatal life. In cattle, nutrient restriction during pregnancy can be a result of environmental or economic factors, but little is known about how it alters the physiology of the fetus and affects future reproductive or growth efficiency. This study used female monozygotic twins, produced through in vitro fertilization and embryo splitting, to determine the effect of moderate maternal nutrient restriction on fetal development. Recipient Angus cross heifers pregnant with one twin were fed a diet meeting 100% National Research Council (NRC) total energy requirements (n = 4; control), whereas recipient heifers pregnant with the second twin were fed at 70% of NRC total energy requirements (n = 4; restricted) from gestational day (GD) 158 to GD 265 in Calan gate feeders. Recipient heifers were killed at GD 265. Change in maternal metabolic body weight was greater from zero in restricted heifers than controls (P < 0.05); restricted heifers lost weight during the nutrient restriction period. There was no difference in last rib back fat or rib eye area between groups (P > 0.10). There was no difference in fetal weight, uterine weight, or total placentome weight between groups (P > 0.10). The pancreas weight was reduced in restricted fetuses compared with control fetuses (P < 0.01), but there were no other differences in fetal organ weights (P > 0.10). Plasma insulin concentrations were reduced in restricted fetuses compared with controls (P < 0.01), but there was no effect of maternal diet on plasma glucose or glucagon concentrations in the fetus (P > 0.10). Histological analyses of the fetal pancreas revealed no differences in endocrine cell number or localization. Results indicate that a modest late gestation nutritional restriction impairs development of the fetal pancreas in the cow. Additional research will be needed to determine if these developmental changes lead to altered glucose and insulin homeostasis in the adult.

Shedding and characterization of gastrointestinal nematodes of growing beef heifers in Central Texas.

Gastrointestinal nematodes (GIN) do not detrimentally affect cattle to the extent of small ruminants. However, they are developing resistance to drugs used to treat them. Genetic strategies to control the nematodes and/or their detrimental effects could be a sustainable alternative to treatment with drugs. An essential first step in development of such a strategy is characterization of nematode populations in commonly used breed types of cattle in local conditions. Fecal egg counts (FEC) were obtained every two months on a cohort of 53 crossbred Nellore-Angus heifers grazing Central Texas pastures from an average heifer age of 3 months to approximately 2 years of age. For 10 of those 12 sets of samples, coprocultures were set up to characterize gastrointestinal nematode species present. Heifers were ½ Nellore ½ Angus (n = 18) or ¾ Angus » Nellore (n = 35). They were born in the spring of 2014 to cows that were from 3-5 years old. They were maintained as a group throughout weaning, postweaning, exposure to bulls as yearlings, and as pregnant cows through the birth of their first calves. An interaction of breed group with sampling time (P < 0.0001) highlighted favorable FEC of » Nellore heifers as compared to ½ Nellore in all but two sampling times. Fecal egg count means were, in general, higher for heifers of both groups in sampling times up to one year of age. Season effects on FEC may be important, but the effect of age may have obscured their detection. There were few significant correlation coefficients for FEC traits with a variety of production traits of these females. Average FEC residuals were positively correlated (r = 0.28 and 0.41; P < 0.05) with winter coat shedding score evaluated at approximately 17 and 24 months of age. Residual correlations of average FEC with calf weaning weight and incidence of shedding with calf age at weaning (r> 0.3) may be indicative of the increased susceptibility of females that lactate heavily or longer to internal parasite infection. Proportions of GIN genera by sampling day differed from χ 2 expectation (P < 0.0001). Cooperia and Haemonchus species were detected in large proportions in sampling dates that corresponded to heifers less than one year of age. Ostertagia and Trichostrongylus species predominated in sampling dates after heifers reached one year of age.

Shedding and characterization of gastrointestinal nematodes of growing beef heifers in Central Texas.

Gastrointestinal nematodes (GIN) do not detrimentally affect cattle to the extent of small ruminants. However, they are developing resistance to drugs used to treat them. Genetic strategies to control the nematodes and/or their detrimental effects could be a sustainable alternative to treatment with drugs. An essential first step in development of such a strategy is characterization of nematode populations in commonly used breed types of cattle in local conditions. Fecal egg counts (FEC) were obtained every two months on a cohort of 53 crossbred Nellore-Angus heifers grazing Central Texas pastures from an average heifer age of 3 months to approximately 2 years of age. For 10 of those 12 sets of samples, coprocultures were set up to characterize gastrointestinal nematode species present. Heifers were ½ Nellore ½ Angus (n = 18) or ¾ Angus » Nellore (n = 35). They were born in the spring of 2014 to cows that were from 3-5 years old. They were maintained as a group throughout weaning, postweaning, exposure to bulls as yearlings, and as pregnant cows through the birth of their first calves. An interaction of breed group with sampling time (P < 0.0001) highlighted favorable FEC of » Nellore heifers as compared to ½ Nellore in all but two sampling times. Fecal egg count means were, in general, higher for heifers of both groups in sampling times up to one year of age. Season effects on FEC may be important, but the effect of age may have obscured their detection. There were few significant correlation coefficients for FEC traits with a variety of production traits of these females. Average FEC residuals were positively correlated (r = 0.28 and 0.41; P < 0.05) with winter coat shedding score evaluated at approximately 17 and 24 months of age. Residual correlations of average FEC with calf weaning weight and incidence of shedding with calf age at weaning (r> 0.3) may be indicative of the increased susceptibility of females that lactate heavily or longer to internal parasite infection. Proportions of GIN genera by sampling day differed from χ2 expectation (P < 0.0001). Cooperia and Haemonchus species were detected in large proportions in sampling dates that corresponded to heifers less than one year of age. Ostertagia and Trichostrongylus species predominated in sampling dates after heifers reached one year of age.

Macrolide-susceptible probiotic Enterococcus faecium ST296 exhibits faecal-environmental-oral microbial community cycling among beef cattle in feedlots.

Enterococci are included in the United States National Antimicrobial Resistance Monitoring System to track antibiotic resistance among commensal Gram-positive enteric bacteria, largely due to their high abundance in food animals and in retail meat. In the U.S. cattle industry, macrolides are used to prevent and control liver abscesses, which cause significant economic losses. Previous studies have suggested that feeding tylosin and the intensity of the pen environment, both expand and sustain respectively the prevalence of multidrug resistance among enterococci in feedlot cattle. This has led to research into alternative feed supplements and improved stewardship practices. In a randomized controlled trial, we measured the impact of a probiotic and an altered pen environment on antimicrobial resistance among faecal Enterococcus spp. in cattle fed tylosin. Supplementing cattle with an Enterococcus faecium and Saccharomyces cerevisiae-based probiotic yielded the isolation of E. faecium of the probiotic sequence type (ST296) from faecal and environmental samples in treatment groups, as well as from cattle and the manure pack in nearby pens. Of importance, the probiotic strain also was found in a desiccated and milled manure pack sample taken 120 days after the initial trial ended. Phylogenetic and SNP analyses revealed clonal survival and spread compatible with faecal-environmental-oral recycling of the probiotic strain within and among cattle and pens. The increase in prevalence of the ST296 strain occurred concomitant with a decrease in ST240, the dominant sequence type associated with ermB and tet(M) resistance genes in this trial. SIGNIFICANCE AND IMPACT OF THE STUDY: We demonstrate that a macrolide-susceptible probiotic Enterococcus faecium ST296 strain fed to beef cattle becomes fully embedded in the microbial community cycling of bacteria via faecal-environmental-oral transmission within and among feedlot pens. An initial investment in feeding the probiotic is thereby leveraged into expanding numbers of susceptible bacteria in cattle and their environment, even among those cattle fed tylosin.

Comparison of Salmonella Prevalence Rates in Bovine Lymph Nodes across Feeding Stages.

Peripheral lymph nodes (LNs) located in the fatty tissues of beef carcasses have been shown to harbor Salmonella and, thus, potentially contaminate ground beef. Salmonella prevalence within LNs is known to differ among feedlots. Two South Texas feeding operations (identified as locations A and B) known to harbor salmonellae in the feedlot environment, while historically producing cattle with opposing rates (one "high" and one "low") of Salmonella prevalence in LNs, were used in this study. To determine whether this difference was due to cattle source or factors associated with different stages of feeding, weanling steers of common and known origin were followed through normal feeding stages at both operations. Eighty Angus-sired beef steers were harvested at each of four feeding stages: 1, postweaning; 2, background or stocker; 3, 60 days on feed; and 4, 120 days on feed. Left and right subiliac and superficial cervical LNs ( n = 304) were collected from each carcass, and similar node types were pooled by animal ( n = 152). Results showed a difference ( P < 0.05) in prevalence of Salmonella in bovine lymph nodes between location A and location B and among feeding stages in location B. Salmonella was not isolated from any feeding stage 1 (postweaning) or location A LN samples. Within location B, there was an increase in Salmonella prevalence as cattle moved into later stages of feeding: at 22.2% (4 of 18), 77.8% (14 of 18), and 94.4% (17 of 18) for feeding stages 2, 3, and 4, respectively. Although the reasons for the differences seen between feeding operations and for increased Salmonella prevalence in LNs at later feeding stages remain unexplained, these results indicate that factors other than cattle source are likely influencing Salmonella prevalence in LNs.

Glucose and acetate metabolism in bovine intramuscular and subcutaneous adipose tissues from steers infused with glucose, propionate, or acetate.

We hypothesized that abomasal infusion of glucose would promote de novo fatty acid biosynthesis from glucose in vitro in bovine intramuscular (i.m.) and subcutaneous (s.c.) adipose tissues to a greater extent than ruminal infusion of acetate, propionate, or glucose. Angus crossbred steers (n = 24), 22 mo of age, were fitted with ruminal cannulas, and steers were adapted to another corn/sorghum finishing diet over a 2-wk period while recovering from the placement of the cannulas. After the adaptation period, the steers were fed the second finishing diet at 130% of their voluntary intake and were infused with isocaloric amounts (3.76 Mcal/d) of glucose, propionate, or acetate for 35 d. Glucose was infused either into the rumen or into the abomasum, whereas propionate and acetate were infused into the rumen. Acetate infusion decreased DM and DE intakes (P < 0.05). The 5th to 8th longissimus muscle section was removed immediately and transported to the laboratory within 10 min post-exsanguination in 38 °C, oxygenated Krebs Henseleit buffer containing 5 mM glucose and 5 mM acetate. Intramuscular and s.c. adipose tissues were dissected from the muscle and incubated in vitro in 5 mM glucose plus 5 mM acetate (containing [U-14C]glucose or [1-14C]acetate). Lipid content was lower (P = 0.04) in i.m. adipose tissue of the acetate-infused steers than in the other treatment groups, and i.m. adipocytes from acetate-infused steers were smaller (P = 0.01) than those from propionate-infused steers. The rate of incorporation of acetate into glyceride-fatty acids (GFA) in i.m. and s.c. adipose tissues was greater (P < 0.03) in steers receiving ruminal or abomasal infusions of glucose than in adipose tissues from steers infused with acetate. The greatest rates of GFA synthesis were observed in s.c. adipose tissue from steers infused ruminally with propionate or abomasally infused with glucose (P < 0.001). In i.m. and s.c. adipose tissues, the proportion of acetyl units from acetate incorporated into GFA was greater in steers receiving glucose infusion in the rumen or abomasum than in steers receiving acetate or propionate infusion (P < 0.05). Contrary to our hypothesis, abomasal glucose infusion did not promote greater fatty acid biosynthesis from glucose in i.m. adipose tissue than ruminal glucose infusion. However, glucose infusion caused the greatest production of acetyl units from acetate in i.m. and s.c. adipose tissues.

Effect of monensin withdrawal on intake, digestion, and ruminal fermentation parameters by Bos taurus indicus and Bos taurus taurus steers consuming bermudagrass hay.

Effects of monensin withdrawal and cattle subspecies on the utilization of bermudagrass hay (14.3% CP, 72.3% NDF, and 36.9% ADF) were evaluated using ruminally cannulated steers (5 [BI] and 5 [BT]). Subspecies were concurrently subjected to a 2-period, 2-treatment crossover design. Treatments consisted of either 0 mg·steer·d-1 monensin with no previous monensin feeding (CON) or withdrawal from 200 mg·steer·d-1 monensin (MON) fed individually in 0.91 kg dried distillers' grains with solubles for 42 d. Withdrawal was evaluated for a 28-d period. Ruminal fluid was collected 2 h after feeding on d 0, 1, 4, 7, 14, and 21 after withdrawal for determination of pH, VFA, ruminal NH-N (RAN), rate of NH production, and CH production rate. Hay, ort, and fecal grab samples were collected d 23 through 28 after withdrawal for determination of intake and digestion. No subspecies × monensin, subspecies × day, or subspecies × monensin × day interactions were observed ( ≥ 0.11). An effect of day after monensin withdrawal was observed ( < 0.01) for total VFA concentration, with an increase following withdrawal followed by a decrease and then stabilization. Monensin × day after monensin withdrawal interactions ( ≤ 0.01) were observed for the acetate:propionate (A:P) ratio and molar percent of acetate and propionate. There was a decrease in molar percent of propionate between d 1 and 4 from 19.1 to 18.0; however, it remained greater ( ≤ 0.10) for MON than CON through d 7. Withdrawal increased molar percent of acetate from 68.3 to 69.8 between d 0 and 4 for MON steers. The A:P ratio was less ( ≤ 0.01) on d 0 for MON than for CON (3.4 vs. 4.0), but by d 4, it increased to 3.8 and was not different ( = 0.14) from CON. By d 14, no differences ( ≥ 0.88) remained for acetate, propionate, or the A:P ratio. After monensin withdrawal, monensin reduced ( < 0.01) RAN by 12.3% (2.09 vs. 1.83 m for CON and MON, respectively). Monensin withdrawal and cattle subspecies had no effect ( ≥ 0.23) on rate of NH production or CH production rate. Monensin withdrawal had no effect ( ≥ 0.45) on intake or digestibility parameters. Greater forage OM intake ( = 0.09; 21.2 vs. 19.2 g/kg BW) and OM digestibility ( < 0.01; 72.4 vs. 63.0%) resulted in greater ( < 0.01) total digestible OM intake (16.8 vs. 13.2 g/kg BW) in BT steers than in BI steers. These results suggest that BT steers are better able to utilize bermudagrass hay than BI steers. Upon monensin withdrawal, steers previously fed monensin continue to have a reduced A:P ratio for at least 7 d.

Association of udder traits with single nucleotide polymorphisms in crossbred Bos indicus-Bos taurus cows.

The size, support, and health of udders limit the productive life of beef cows, especially those with background, because, in general, such cows have a reputation for problems with udders. Genomic association studies of bovine udder traits have been conducted in dairy cattle and recently in Continental European beef breeds but not in cows with background. The objective of this study was to determine associations of SNP and udder support scores, teat length, and teat diameter in half (Nellore), half (Angus) cows. Udders of cows ( = 295) born from 2003 to 2007 were evaluated for udder support and teat length and diameter ( = 1,746 records) from 2005 through 2014. These included a subjective score representing udder support (values of 1 indicated poorly supported, pendulous udders and values of 9 indicated very well-supported udders) and lengths and diameters of individual teats in the 4 udder quarters as well as the average. Cows were in full-sibling or half-sibling families. Residuals for each trait were produced from repeated records models with cow age category nested within birth year of cows. Those residuals were averaged to become the dependent variables for genomewide association analyses. Regression analyses of those dependent variables included genotypic values as explanatory variables for 34,980 SNP from a commercially available array and included the genomic relationship matrix. Fifteen SNP loci on BTA 5 were associated (false discovery rate controlled at 0.05) with udder support score. One of those was also detected as associated with average teat diameter. Three of those 15 SNP were located within genes, including one each in (), (), and (). These are notable for their functional role in some aspect of mammary gland formation or health. Other candidate genes for these traits in the vicinity of the SNP loci include () and (). Because these were detected in Nellore-Angus crossbred cows, which typically have very well-formed udders with excellent support across their productive lives, similar efforts in other breeds should be completed, because that may facilitate further refinement of genomic regions responsible for variation in udder traits important in multiple breeds.

Effect of monensin inclusion on intake, digestion, and ruminal fermentation parameters by Bos taurus indicus and Bos taurus taurus steers consuming bermudagrass hay.

Effects of monensin inclusion and cattle subspecies on utilization of bermudagrass hay (13.7% CP, 77.3% NDF, and 38.8% ADF) were evaluated using ruminally cannulated steers (5 [BI] and 5 [BT]; 398 kg BW). Subspecies were concurrently subjected to a 2-period, 2-treatment crossover design. Treatments were 0 (CON) or 200 mg·steer·d monensin (MON) in 0.91 kg dried distillers' grains with solubles. Periods were 70 d in length: 20 d of adaptation, 22 d of sample collection, and 28 d for withdrawal of treatment. Steers were group housed during adaptation and moved to individual covered pens for sampling. Hay, ort, and fecal grab samples were collected d 21 through 25 for determination of intake and digestion. Ruminal fluid was collected with a suction strainer 0, 2, 4, 8, and 12 h after feeding on d 42 for pH, VFA, and ruminal NH-N (RAN) analysis. Additionally, at h 2, ruminal fluid and contents were collected for determination of rate of NH production and CH production rate. No subspecies × monensin interactions were observed ( ≥ 0.12). Monensin had no effect ( ≥ 0.16) on intake or digestibility parameters. No subspecies effect ( ≥ 0.11) was observed for forage OM intake, total OM intake, or OM digestion. Total digestible OM intake tended to be greater ( = 0.06) for BT steers than for BI steers (14.0 vs. 12.2 g/kg BW). There was an effect of hour after feeding ( ≤ 0.01) on pH, total VFA, acetate:propionate ratio, and molar percent acetate and propionate. Total VFA concentration was greater ( = 0.01) in CON steers than in MON steers (66.5 vs. 62.0 m). Monensin decreased molar percent acetate ( = 0.02) from 72.5 to 71.2% and increased molar percent propionate ( < 0.01) from 16.9 to 18.7%, resulting in a reduced ( < 0.01) acetate:propionate ratio (from 4.34 to 3.85). Although not significantly ( = 0.19), monensin numerically reduced the CH production rate by 15.8%. Greater ( = 0.07) CH production rate tended to be observed in BI steers than in BT steers (21.4 vs. 16.6 µmol CH·mL·h, respectively). Monensin had no effect ( ≥ 0.32) on pH, RAN, or rate of NH production. A subspecies × hour after feeding interaction was observed for RAN, with BT having greater RAN at h 0 and 4, whereas BI had greater RAN at h 2, 8, and 12. Overall, monensin decreased the acetate:propionate ratio and total VFA concentration but had no effect on forage utilization. steers consumed less digestible OM and had a greater CH production rate compared with BT steers, suggesting BT were better able to utilize the available forage resource than BI.

Effect of source and level of protein supplementation on rice straw utilization by Brahman steers.

Seven ruminally cannulated Brahman steers were used in a 7 × 4 incomplete block design to determine the effects of cottonseed meal (CSM; 43.9% CP, 82.9% RDP) or dried distillers' grains (DDG; 27.5% CP, 43.6% RDP) supplementation on rice straw utilization (47 g/kg CP and 681 g/kg NDF). Treatments consisted of a negative control receiving no supplement (control) and 3 levels (60, 120, and 180 mg N/kg BW) of either CSM or DDG. Periods were 14 d with 8 d for adaptation and 6 d for data collection. Steers had ad libitum access to rice straw and were fed supplements daily. Increased supplementation resulted in a linear increase ( ≤ 0.06) in forage OM intake from 13.5 g/kg BW by controls to 15.5 and 16.1 g/kg BW for 180 mg N/kg BW of DDG and CSM, respectively. No differences between sources were observed ( = 0.84). Total digestible OM intake was increased by supplementation (linear, < 0.01) from 6.9 g/kg BW (control) to 10.0 and 11.2 g/kg BW for 180 mg N/kg BW of CSM and DDG, respectively. A greater response was observed for DDG ( = 0.05) due to greater provision of supplement (g DM/d) to achieve isonitrogenous treatment levels. Total tract OM digestion tended to increase with DDG supplementation (linear, = 0.08) but not CSM supplementation ( = 0.19). Both supplements did not affect NDF digestion ( > 0.40) or calculated forage NDF digestibility ( > 0.40). Ruminal ammonia concentrations peaked 4 h after supplementation/feeding with the greatest concentration (4.0 m) observed for 180 mg N/kg BW of CSM and the lowest concentration at 4 h observed in the control (0.8 m). Provision of CSM resulted in a linear increase ( < 0.01) in average ruminal ammonia, in contrast to the quadratic response ( = 0.02) observed with DDG supplementation. Total VFA production linearly increased for both CSM and DDG supplementation ( = 0.09 and = 0.01, respectively). Protein supplements containing high and low levels of RDP were effective at improving intake and utilization of rice straw by Brahman steers.

Impact of exercise on productivity, behavior, and immune functioning of weaned Bos indicus-cross calves housed in drylots.

The effects of 2 exercise regimes on cattle productivity, immune function, and behavior were evaluated against a control ( = 4 pens/treatment) using weaned -cross calves ( = 203) housed in drylots (16-18 calves/single sex pens). Three treatments were applied 3 times per week for 4 wk: 1) programmatic exercise (PRO), in which cattle and a stockperson walked in the alleyway behind their home pen for 20 min; 2) free exercise (FREE), in which cattle were moved into the drovers alley for 60 min, not exercised by a stockperson, and were allowed free access to their home pen and alleyway; and 3) control (CON), in which calves were removed from their home pen only for routine husbandry. Behavior observations were conducted on d -2 and -1 relative to treatment implementation (d 0) and on d 5, 6, 12, 13, 19, 20, 26, and 27. Instantaneous scan sampling was used to create behavioral profiles for cattle (posture: stand, lie, and walk; and behavior: feed, drink, and ruminate). Focal observations recorded the incidence of social behaviors (allogrooming, social play, and agonistic interactions) and animal-environment interactions (AEI; fencepost licking, rock eating, tongue rolling, and cross-suckling). Body weights, exit velocities, and antibody titers to a bovine viral diarrhea virus type 1b vaccine were measured on d -10, 10, and 28. A linear mixed model (PROC MIXED) was used to evaluate the impact of exercise treatment, sex, time, and their interactions on cattle behavior, health, and productivity. Statistical differences were not observed ( = 0.11) for overall ADG among cattle receiving FREE (1.00 kg ± 0.04) PRO (0.85 kg ± 0.04), or CON (0.86 kg ± 0.05) exercise treatments. Allogrooming ( = 0.05), lying ( < 0. 01), AEI ( < 0.01), rumination ( < 0.01), and agonistic interactions ( < 0.01) increased over time. Comfort-related behaviors (e.g., lying, rumination) increased over the evaluation period, suggesting that calves became acclimated to the environment. Exercise did not alter behaviors or vaccine response and did not reduce the performance of production-critical (e.g., feeding, resting, ruminating) behaviors.

Antibody titers to vaccination are not predictive of level of protection against a BVDV type 1b challenge in Bos indicus - Bos taurus steers.

Subclinical illness associated with infection is thought to reduce performance and increase production costs in feedlot cattle, but underlying components remain largely unidentified. Vaccination is frequently used in feedlot settings but producers lack metrics that evaluate the effectiveness of vaccination programs. The goal of this study was to determine if levels of serum neutralizing antibody titers were predictive of levels of vaccine protection in a commercial setting. During this four-year study, Angus-Nellore steers housed in a production feedlot setting were assigned to 1 of 3 vaccine treatments: killed vaccine (kV), modified live virus (MLV) vaccine, or no vaccine (control), and were challenged with a noncytopathic 1b field strain of bovine viral diarrhea virus. Rectal temperature and levels of circulating lymphocytes and platelets were monitored following challenge. While no animals were diagnosed as clinically ill with respiratory disease, indicators of disease (pyrexia, lymphopenia, and thrombocytopenia) were observed. The MLV treatment elicited higher antibody titers to the vaccination than the kV, and calves in the MLV treatment had higher mean titers at challenge. The year that elicited the highest antibody response to the vaccination and the year with the lowest frequency of phenotypic responses to the challenge were not concurrent. The MLV treatment had the highest proportion, 34.68%, of animals that were protected against the challenge regardless of the pre-challenge antibody titer and had the fewest number of lymphopenia cases in response to the challenge. Both vaccine treatments mitigated thrombocytopenia when compared to the control treatment, and the MLV treatment reduced lymphopenia; however, these symptoms were not completely eliminated in vaccinated animals. Pyrexia was present in 40.11% of the animals, but no difference in the frequency of cases between treatments was observed. Pre-challenge vaccination response was not indicative of the level of protection nor was anamnestic antibody response correlated with health status.

The influence of taste in willingness-to-pay valuations of sirloin steaks from postextraction algal residue-fed cattle.

Consumer preferences and willingness-to-pay (WTP) for beef sirloin steaks with differing production, physical, and credence attributes related to the use of postextraction algal residue (PEAR), a novel feed ingredient, were estimated. Ninety-six consumers participated in a sensory tasting panel before completing a choice set survey; 127 consumers completed only the choice set survey without sampling products. Steaks from grain- and PEAR-fed steers had similar Warner-Bratzler shear force (WBSF) scores (1.89 kg and 2.01 kg, respectively; = 0.77) and had lower WBSF scores than steaks from grass-fed steers (3.37 kg; < 0.05). Eicosapentaenoic acid (20:5) was not different among steaks from grain- and PEAR-fed steers ( = 0.39) but was greater compared with steaks from grass-fed cattle ( ≤ 0.03). Panelists in the sensory portion of the study evaluated beef samples for like/dislike of overall sample, overall flavor, beefy flavor, and juiciness. Panelist rating of overall like, overall flavor like, and beefy flavor like were not different between the PEAR- and grain-fed treatments ( > 0.26). Panelists rated the juiciness like/dislike of steaks from PEAR-fed cattle the highest ( < 0.01) among the 3 samples. Sensory tasting of the products was observed to alter the preferences of consumers. Consumers who completed only the survey negatively perceived beef from PEAR-fed cattle compared with beef from grain-fed cattle, with a WTP discount of -US$1.17/kg. However, with sensory tasting, the WTP for beef from PEAR-fed cattle was not discounted relative to beef from grain-fed cattle ( = 0.21). The nontasting consumers had much higher stated WTP values for credence attributes. Factors that influence the eating experience (tenderness and quality grade) dominated as the most important attributes on WTP among the tasting group. The use of no hormones and no antibiotics in production had a premium of $2.34/kg among the nontasting group, but with tasting, the premium was $1.19/kg. If PEAR-fed beef came to market, there would be no need to differentiate it from grain-fed beef unless retailers wanted to market it as a differentiated product. If it were marketed as a differentiated product, retailers would need to hold promotional tastings to change consumer's preconceived notions about the product.

Crossbred steer temperament as yearlings and whole genome association of steer temperament as yearlings and calf temperament post-weaning.

cattle often have the reputation for a poor or dangerous temperament. Identification of genomic regions that associate with temperament of such cattle may be useful for genetic improvement strategies. The objectives of this study were to evaluate subjective temperament scores (1 to 9; higher scores indicated more unfavorable temperament) for aggressiveness, nervousness, flightiness, gregariousness, and overall temperament of one-half steers in feedlot conditions at 1 yr of age and compare those scores of those steers when evaluated approximately 1 mo postweaning, and conduct whole genome association analyses using SNP markers and the temperament traits of those steers at 1 yr of age and for temperament traits of all calves at weaning. Contemporary groups ( < 0.001) were steers born in the same year and season, and fed in the same feedlot pen. Aggressiveness of steers at 1 yr of age was not associated with aggressiveness at weaning (linear regression coefficient did not differ from 0; = 0.96), but regressions of all other yearling scores of steers on the scores at weaning were positive (coefficients ranged from 0.26 ± 0.04 to 0.32 ± 0.04; < 0.001). Estimates of Pearson correlation coefficients (using unadjusted values and residual values) of the different traits measured at 1 yr of age were large ( > 0.63; < 0.008) except for aggressiveness with nervousness, flightiness, or gregariousness, which did not differ from 0 ( > 0.1). Five SNP on BTA 1, 24, and 29 had suggestive associations (0.17 < [adjusted for FDR] < 0.24) with aggressiveness, nervousness, or flightiness at evaluation postweaning and 13 SNP on 11 chromosomes had suggestive associations (0.07 < [adjusted for FDR] < 0.24) with aggressiveness, nervousness, flightiness, or overall temperament score of steers at 1 yr of age. Genes close to these loci with roles in neural systems of various organisms included synaptotagmin 4 (BTA 24), FAT atypical cadhedrin 3 (BTA 29), tubulin tyrosine ligase-like 1 (BTA 5), spermatogenesis associated 17 (BTA 16), stanniocalcin 2 (BTA 20), and GABA receptor γ 3 (BTA 21).

Effect of postextraction algal residue supplementation on the ruminal microbiome of steers consuming low-quality forage.

Cattle consuming low-quality forages (LQF) require protein supplementation to increase forage utilization via ruminal fermentation. Biofuel production from algal biomass results in large quantities of postextraction algal residue (PEAR), which has the potential to elicit LQF utilization responses similar to cottonseed meal (CSM); however, its effect on ruminal bacterial communities is unknown. Five ruminally and duodenally cannulated Angus steers in a 5 × 5 Latin square had ad libitum access to oat straw diets. Treatments were infused ruminally and consisted of an unsupplemented control; PEAR at 50, 100, and 150 mg N/kg BW; and CSM at 100 mg N/kg BW. Ruminal samples were collected 4 h after supplementation on d 14 of each period and separated into solid and liquid fractions. Each sample was extracted for genomic DNA, PCR amplified for the V4 to V6 region of the 16S rRNA, sequenced on the 454 Roche pyrosequencing platform, and analyzed using the QIIME pipeline. Weighted UniFrac analysis and Morisita-Horn index demonstrated different community composition between liquid and solid fractions. Measures of richness including observed operational taxonomic units (OTU) and abundance coverage estimator metric decreased with greater PEAR provision (P ≤ 0.09). There were 42 core microbiome OTU observed in all solid fraction samples while the liquid fraction samples contained 30 core OTU. Bacteroidetes was the predominant phylum followed by Firmicutes in both fractions, which together characterized more than 90% of sequences. Relative abundance of Firmicutes increased with PEAR supplementation in the liquid fraction (linear, P = 0.02). Among Firmicutes, Lachnospiraceae, Ruminococcaceae, and Clostridiaceae families increased in the liquid fraction with greater PEAR supplementation (linear, P ≤ 0.03). Prevotella represented over 25% of sequences in all treatments, and relative abundance decreased in the solid fraction with increasing PEAR provision (linear, P = 0.01). Fibrobacter and Treponema decreased in the liquid fraction with increasing PEAR (linear, P < 0.10). Results suggest PEAR supplementation increased forage utilization by increasing members of Firmicutes within the liquid fraction of the rumen microbiome.

Effect of increasing amounts of postextraction algal residue on straw utilization in steers.

Algal biomass has been identified as a third-generation biofuel. Significant quantities of the coproduct postextraction algal residue (PEAR) remain after lipid extraction. After extraction, PEAR is concentrated in protein (17.9% CP on a DM basis and 32.5% CP on an ash-free basis), suggesting it may be an alternative to cottonseed meal (CSM) as a protein supplement. Our objectives were to determine the optimal level of PEAR supplementation to steers consuming straw and to compare the effects of PEAR supplementation on straw utilization and N metabolism with an isonitrogenous level of CSM. Five steers (198.2 ± 6.1 kg of BW), in a 5 × 5 Latin square, had ad libitum access to oat straw (80% NDF and 4.5% CP on a DM basis). Treatments were infused ruminally once daily and included no supplemental protein (CON); PEAR at 50, 100, and 150 mg N/kg BW; and CSM at 100 mg N/kg BW. Provision of PEAR increased total digestible OM intake (TDOMI) quadratically (P = 0.01) from 0.9 (CON) to 1.6 kg/d (100 mg N/kg BW of PEAR). Organic matter digestibility (OMD) increased quadratically (P < 0.01) with supplementation and was maximized (55% OMD) at 50 mg N/kg BW of PEAR. At isonitrogenous levels of PEAR and CSM, TDOMI was similar (P = 0.13) as was OMD (P = 0.50). Negative N balance was observed for all treatments except PEAR provided at 100 or 150 mg of N/kg BW. Nitrogen balance was quadratic (P < 0.01) with the greatest retention (1.84 g N/d) occurring at 100 mg N/kg BW of PEAR. There were no differences (P ≥ 0.22) between isonitrogenous PEAR and CSM supplementation in measurements of ruminal ammonia or VFA concentrations. Straw utilization was maximized when PEAR was provided at 100 mg N/kg BW. Our observations suggest cattle provided PEAR utilize straw in a manner similar to those supplemented CSM, indicating PEAR has potential to substitute for CSM as a protein supplement in forage-based operations.

Genetic evaluation of aspects of temperament in Nellore-Angus calves.

The objective of this work was to estimate heritability of each of 5 subjectively measured aspects of temperament of cattle and the genetic correlations of pairs of those traits. From 2003 to 2013, Nellore-Angus F2 and F3 calves (n = 1,816) were evaluated for aspects of temperament at an average 259 d of age, which was approximately 2 mo after weaning. Calves were separated from a group and subjectively scored from 1 (calm, good temperament) to 9 (wild, poor temperament) for aggressiveness (willingness to hit an evaluator), nervousness, flightiness, gregariousness (willingness to separate from the group), and a distinct overall score by 4 evaluators. Data were analyzed using threshold and linear models with additive genetic random effects. Two-trait animal models (nonthreshold) included the additive genetic covariance for pairs of traits and were used to estimate additive genetic correlations. Contemporary groups (n = 104) represented calves penned together for evaluation on given evaluation days. Heifers had greater (worse) means for all traits than steers (P < 0.05). The regression of score on age in days was included in final models for flightiness (P = 0.05; -0.006 ± 0.003) and gregariousness (P = 0.025; -0.007 ± 0.003). Estimates of heritability were large (0.51, 0.4, 0.45, 0.49, and 0.47 for aggressiveness, nervousness, flightiness, gregariousness, and overall temperament, respectively; SE = 0.07 for each). The ability to use this methodology to distinctly separate different aspects of calf temperament appeared to be limited, as estimates of additive genetic correlations were near unity for all pairs of traits; estimates of phenotypic correlation ranged from 0.88 ± 0.01 to 0.99 ± 0.002 for pairs of traits. Distinct subsequent analyses indicated a significant negative relationship of 4 of the various temperament scores with weight at weaning (regression coefficients ranged from -0.008 ± 0.002 for nervousness, flightiness, and gregariousness to -0.003 ± 0.002 for aggressiveness). In subsequent analyses, the regression of temperament trait on sequence of evaluation within a pen was highly significant and solutions ranged from 0.05 ± 0.007 for aggressiveness to 0.08 ± 0.007 for all other traits. The apparent large additive genetic variance for any one of these traits may be useful in identification of genes responsible for differences in cattle temperament.