Invited Review: Limitations to current mineral requirement systems for cattle and potential improvements.

The mineral requirements or recommendations generated by various NASEM committees are used by many ration formulation programs. The current NASEM dairy requirement system uses the factorial approach (requirements for maintenance, lactation, gestation, and growth) for most minerals but when data or equations were not available to estimate factorial requirements the committee used available data to estimate adequate intake values. The current beef NASEM uses the factorial method for Ca and P and recommendations for the other minerals. The factorial method works well for Ca and P because adequate data are available to estimate absorption coefficients (AC) and maintenance requirements. In addition, feeding Ca and P above requirements have few if any positive effects. For many other minerals the factorial method is problematic. Estimating both the maintenance requirement and AC can be extremely difficult and inaccuracies in those values have a major impact on accuracy of total dietary requirements. Some minerals have positive effects on health, production and reproduction when fed above factorially determined requirements. For those minerals response models rather than or in addition to requirement models are more appropriate. The AC is in the denominator of the factorial equation and converts absorbed requirements into dietary requirements. The AC for trace minerals is small, often <0.1, and small changes in a low AC can have substantial effects on dietary requirements. Although accurate AC are essential for the factorial method to work, woefully few data are available on the true absorption of trace minerals. Because of antagonism to absorption (e.g., negative effect of S on absorption of Cu, Mn, Se, and Zn) equations will be needed to estimate AC under different dietary conditions but current data is inaccurate to generate equations. The systems currently used will almost always prevent clinical mineral deficiencies, but because of uncertainties, most nutritionists formulate diets to exceed and often far exceed established recommendations. This leads to increased costs, potential antagonism, and increased manure excretion of environmentally important minerals. More accurate systems for estimating mineral requirements will optimize animal performance and health while keeping costs in check and reduce environmental damage.

Effects of physical preparation of diets and inclusion rate of modified wet distillers grains with solubles on production and rumen measurements of lactating dairy cows.

Our objective was to determine if methods for preparing total mixed ration [TMR; horizontal paddle mixer with knives (PK) vs. vertical auger (VA) mixer] would alter the physical form of the TMR and affect utilization of diets with increasing amounts of modified wet distillers grains with solubles (MWDGS). Holstein cows (n = 24 with 12 ruminally cannulated; 144 d in milk ± 31 d at start) were used in a split-plot design with mixer type as the whole plot and MWDGS concentrations as subplots in a replicated 3 × 3 Latin square arrangement with 35-d periods. Inclusion rates of MWDGS were 10, 20, and 30% of dietary dry matter, primarily replacing corn, soybean meal, soyhulls, and whole cottonseed. Feed dry matter intake (DMI) was less for PK (23.8 kg/d) than for VA (25.7 kg/d), but was unaffected by MWDGS concentration. Milk production did not differ by concentration of MWDGS or by interaction of MWDGS × mixer. Milk fat percentage declined with increasing MWDGS but the interaction between mixer and MWDGS showed that decreases were larger with VA mixing. Cows fed the diet containing 30% MWDGS mixed with PK averaged 3.45% (1.24 kg/d) milk fat, whereas cows fed the same diet mixed with VA averaged 2.81% (1.10 kg/d) fat. Concentrations of trans-10,cis-12 C18:2 in milk fat likely explain the differences observed in milk fat yield; the concentration of trans-10,cis-12 C18:2 increased as MWDGS was increased and the MWDGS × mixer interaction showed that VA had greater concentrations. Greater mean particle size and increased variation in particle size with VA may partially explain differences in milk fat via increased sorting that allowed for an altered rumen environment and favored alternative biohydrogenation pathways. Feed conversion efficiency (FCE; energy-corrected milk/DMI) decreased linearly as MWDGS increased, but FCE tended to be maintained when higher MWDGS diets were mixed using PK rather than VA. Ruminal pH and ammonia concentration decreased linearly as MWDGS increased. The PK mixer resulted in greater FCE when higher amounts of MWDGS were fed, primarily because milk fat content and yield were not as depressed and DMI was lower at similar milk yields.

The effect of trace mineral source and concentration on ruminal digestion and mineral solubility.

The objective of this experiment was to compare the effect of sources of sulfate trace mineral (STM) and hydroxy trace mineral (HTM) at different inclusions on digestibility of dry matter (DM) and neutral detergent fiber and solubility of Cu, Mn, and Zn in the rumen and abomasum of cattle. Five ruminally cannulated steers were used in a 5×5 Latin square design and individually fed a corn silage-based diet on an ad libitum basis. The 5 dietary treatments were as follows: control: no supplemental Cu, Mn, or Zn, analyzed to contain 7.4mg of Cu, 30.8mg of Mn, and 32.1mg of Zn per kilogram of diet DM (CON); low sulfate: 5mg of Cu/kg of DM supplemented from CuSO4, 15mg of Mn/kg of DM from MnSO4, and 30mg of Zn/kg of DM from ZnSO4; low HTM: 5mg of Cu/kg of DM supplemented from basic copper chloride (IntelliBond C; Micronutrients Inc., Indianapolis, IN), 15mg of Mn/kg of DM from manganese hydroxychloride (IntelliBond M; Micronutrients Inc.), and 30mg of Zn/kg of DM from zinc hydroxychloride (IntelliBond Z; Micronutrients Inc.); high sulfate: 25mg of Cu/kg of DM supplemented from CuSO4, 60mg of Mn/kg of DM from MnSO4, and 120mg of Zn/kg of DM from ZnSO4; and high HTM: 25mg of Cu/kg of DM supplemented from basic copper chloride, 60mg of Mn/kg of DM from manganese hydroxychloride, and 120mg of Zn/kg of DM from zinc hydroxychloride. Periods lasted for 12d, with 10d of diet adaptation. Dacron bags containing the CON total mixed ration were inserted on d 11 at 0h and were removed at 6, 12, 24, and 36h after insertion. Dry matter and neutral detergent fiber disappearances and rumen and simulated abomasal trace mineral solubilities were evaluated. Dietary treatment did not affect DM intake. Dry matter disappearance was lesser in supplemental TM treatments and greater in CON than the STM treatments, although the CON and HTM treatments did not differ. Neutral detergent fiber disappearance was not affected by treatment. Ruminally soluble Cu and Mn concentrations were least in CON and were lesser in HTM-containing treatments compared with STM treatments. However, in the abomasum, solubilities of Cu and Mn were similar across trace mineral sources. Ruminal and simulated abomasal soluble Zn was greater in the HTM treatments than in CON and STM, driven by the greater solubility of the high HTM treatment. Under the conditions of this study, supplementing trace minerals as STM decreased DM digestibility, whereas HTM did not affect DM digestibility. Additionally, Cu and Mn from HTM sources were relatively insoluble in the rumen but had similar solubility as STM at the pH found in the abomasum, suggesting that these minerals should be available for absorption in the intestine.

A Novel Whole Tissue Explant Model of Hidradenitis Suppurativa.

Hidradenitis Suppurativa (HS) is a relatively common and highly morbid inflammatory skin disease. Due to our relatively limited understanding of HS's pathogenesis, there are currently insufficient treatment options available, and many patients' medical needs are not being met. This is partly due to a scarcity of ex vivo human assays and animal models that accurately recapitulate the disease. To address this deficit, we have developed a whole-tissue explant model of HS to examine its pathogenic mechanisms and the efficacy of potential treatments within intact human tissue. We measured cytokine protein and RNA within whole tissue maintained in an agar-media solution, finding that IL-6 and IL-8 concentrations trended upwards in both HS explants and healthy controls, while IL-17A, IL-1ß, and TNF-α exhibited increases in HS tissue alone. We also show that the explants were responsive to treatment with both dexamethasone and IL-2. Not only do our results show that this model effectively delivers treatments throughout the explants, but they also elucidate which cytokines are related to the explant process regardless of tissue state and which are related to HS tissue specifically, laying the groundwork for future implementations of this model.

Long-distance transit alters liver and skeletal muscle physiology of beef cattle.

Transportation of cattle is necessary but negatively impacts animal health and production efficiency. To gain a better understanding of the physiological responses to long-distance road transit, 36 crossbred beef steers (324 ±â€¯36 kg) were randomly assigned to treatments (n = 12 steers/treatment): no transit and ad libitum access to feed and water (CON), no transit but deprived of feed and water for 18 h (DEPR), or road transit and no access to feed or water for 18 h (1 790 km; TRANS). Blood, liver, and muscle (longissimus dorsi) samples were collected pre- and post-treatment for analysis of blood metabolites, blood leukocyte profiles, blood markers of oxidative stress, and tissue antioxidant enzyme activity. Additionally, discovery-based metabolomics and proteomics analyses were performed on tissue samples collected immediately post-treatment (d 1). Data (except for omics) were analyzed using ProcMixed of SAS 9.4 with the fixed effect of treatment and steer as the experimental unit. Omics data were analyzed using MetaboAnalyst; metabolites and proteins of interest were identified based on a fold change threshold of 1.20 and t-test P-value of 0.10. On d 1, percent of pretreatment BW and DM intake were least for TRANS steers (P ≤ 0.06). Percent of pretreatment BW remained lesser for TRANS steers on d 8 (P = 0.05). Serum haptoglobin was greatest for TRANS steers immediately post-treatment (P = 0.02). Additionally, TRANS steers exhibited the greatest increase in the neutrophil to lymphocyte ratio and serum non-esterified fatty acids during the treatment period (P < 0.01), indicating TRANS steers experienced a more robust inflammatory and neuroendocrine response. Immediately post-treatment, liver superoxide dismutase activity tended to be greatest for both DEPR and TRANS (P = 0.07) while muscle superoxide dismutase activity was only greatest for TRANS (P = 0.02), suggesting TRANS steers may have experienced more oxidative stress due to the additional physical effort required to stand and maintain balance during transit. The abundance of several proteins (alpha-2-HS-glycoprotein) and metabolites (lactate, citrate, tri-hydroxybutyric acid, and leucine) associated with energy metabolism were altered in the liver and muscle of TRANS. The differential responses for DEPR versus TRANS steers indicate muscle plays an important role in how cattle respond to and recover from transportation stress.

High dietary iron reduces transporters involved in iron and manganese metabolism and increases intestinal permeability in calves.

A 56-d experiment was designed to examine the effect of high dietary Fe on metal transporters involved in Fe and Mn metabolism. Fourteen weaned Holstein calves were stratified by weight and randomly assigned to 1 of 2 treatments: 1) no supplemental Fe (normal Fe) or 2) 750mg of supplemental Fe/kg of dry matter (high Fe). Jugular blood was collected on d 0, 35, and 56. At the end of the trial, 6 calves per treatment were humanely killed and duodenal scrapings, liver, and heart were collected for analysis. Additionally, proximal duodenum was mounted on Ussing chambers to assess intestinal barrier integrity. Calves receiving high dietary Fe displayed decreased transepithelial resistance and increased apical-to-basolateral flux of radiolabeled mannitol, suggesting that high Fe created increased intestinal permeability. Feeding calves a diet high in Fe decreased average daily gain, dry matter intake, and feed efficiency. Hemoglobin and serum Fe concentrations did not differ due to dietary treatment. High dietary Fe increased concentrations of Fe in the liver, but did not affect heart or duodenal Fe concentrations. Duodenal Mn concentrations were lowered by feeding a high Fe diet, but liver and heart Mn concentrations were not affected. As determined by real-time reverse transcription PCR, relative hepatic expression of the gene that encodes the Fe regulatory hormone hepcidin was 5-fold greater in calves fed high dietary Fe. Hepcidin is released in response to increased Fe status and binds to the Fe export protein ferroportin causing ferroportin to be degraded, thereby reducing dietary Fe absorption. Confirmation of this result was achieved through Western blotting of duodenal protein, which revealed that ferroportin was decreased in calves fed high dietary Fe. Duodenal protein expression of divalent metal transporter 1 (DMT1), a Fe import protein that can also transport Mn, tended to be reduced by high dietary Fe. Transcript levels of several genes involved in Fe metabolism in liver and duodenum were unchanged by treatment. In summary, feeding calves a diet high in Fe induced a signal cascade (hepcidin) designed to reduce absorption of Fe (via reduced protein expression of ferroportin and DMT1) in a manner similar to that reported in rodents. Additionally, reduced levels of DMT1 protein appeared to decrease duodenal Mn, suggesting that Mn may also be a substrate for DMT1 in cattle.

Pre-transit vitamin C injection improves post-transit performance of beef steers.

Although cattle can synthesize vitamin C (VC) endogenously, stress may increase VC requirements above the biosynthetic threshold and warrant supplementation. This study investigated the effects of a VC injection delivered before or after a long-distance transit event on blood parameters and feedlot performance of beef steers. Fifty-two days prior to trial initiation, 90 newly weaned, Angus-based steers from a single source were transported to Ames, IA, USA. On day 0, 72 steers (356 ± 17 kg) were blocked by BW and randomly assigned to intramuscular injection treatments (24 steers/treatment): saline injection pre- and post-transit (CON), VC (Vet One, Boise, ID, USA; 5 g sodium ascorbate/steer) injection pre-transit and saline injection post-transit (PRE) or saline injection pre-transit and VC injection post-transit (POST). Following pre-transit treatment injections, steers were transported on a commercial livestock trailer for approximately 18 h (1675 km). Post-transit (day 1), steers were sorted into pens with one GrowSafe bunk/pen (4 pens/treatment; 6 steers/pen). Steers were weighed on day 0, 1, 7, 30, 31, 56 and 57. Blood was collected from 3 steers/pen on day 0, 1, 2 and 7; liver biopsies were performed on the same 3 steers/pen on day 2. Data were analyzed as a randomized complete block design (experimental unit = steer; fixed effects = treatment and block) and blood parameters were analyzed as repeated measures. A pre-transit VC injection improved steer average daily gain from day 7 to 31 (P = 0.05) and overall (day 1 to 57; P = 0.02), resulting in greater BW for PRE-steers on day 30/31 (P = 0.03) and a tendency for greater final BW (day 56/57; P = 0.07). Steers that received VC pre- or post-transit had greater DM intake from day 31 to 57 (P = 0.01) and overall (P = 0.02) v. CON-steers. Plasma ascorbate concentrations were greatest for PRE-steers on day 1 and POST-steers on day 2 (treatment × day; P < 0.01). No interaction or treatment effects were observed for other blood parameters (P ≥ 0.21). Plasma ferric-reducing antioxidant potential and malondialdehyde concentrations decreased post-transit (day; P < 0.01), while serum non-esterified fatty acids and haptoglobin concentrations increased post-transit (day; P < 0.01). In general, blood parameters returned to pre-transit values by day 7. Pre-transit administration of injectable VC to beef steers mitigated the decline in plasma ascorbate concentrations and resulted in superior feedlot performance compared to post-transit administration.

Bioaccessibility of iron from soil is increased by silage fermentation.

High dietary Fe can negatively affect absorption of other minerals and cause tissue damage through the production of free radicals. Cattle are often exposed to high dietary Fe, and soil ingestion may represent a major dietary source of Fe. Iron in soil is often found in the ferric form bound in insoluble complexes; however, exposure to an acidic environment similar to that occurring during silage fermentation may cause this Fe to be reduced to the more soluble ferrous form. To test this theory, a 2 x 2 x 3 factorial arrangement examining time, level, and type of soil addition to greenchop was used. Factors included 2 times of soil addition (before or after ensiling), 2 levels of soil inclusion (1 and 5% contamination, wet basis) and 3 types of soil (Cecil clay loam, 3.4% Fe; Georgeville silt loam, 4.3% Fe; and Dyke clay loam, 6.9% Fe). In addition, greenchop with no soil added was ensiled to serve as a control. Fresh corn greenchop was mixed with the appropriate type and level of soil and tightly packed in experimental silos. Fermentation was allowed to proceed for 90 d before silos were opened and silage was freeze-dried and ground. To simulate contamination after ensiling, each soil type was added to control silage at the 2 levels of inclusion. Addition of soil to greenchop before ensiling resulted in greater amounts of water soluble Fe compared with soil addition after ensiling, suggesting that Fe-soil binding properties were altered by ensiling. To test the potential bioaccessibility of Fe during ruminant digestion, an enzymatic in vitro system was modified to simulate ruminal, abomasal, and intestinal digestion. The presence of soil, regardless of time of addition, type, or inclusion level, resulted in greater soluble or bioaccessible Fe concentrations after all 3 phases when compared with control silage. Ensiling further increased soluble Fe concentrations after each phase when compared with silage contaminated with soil after ensiling. In addition, dialyzable Fe concentration (15,000 Da molecular weight cut off) following intestinal phase simulation was greater due to ensiling. Iron that becomes soluble during the intestinal phase may be available to the animal for absorption, and ensiling resulted in increased concentrations of potentially bioavailable Fe. These results suggest that soil contamination of harvested feeds before ensiling may represent a major source of bioavailable Fe in the diets of cattle.

Aerobic scope for activity in age 0 year Atlantic cod Gadus morhua.

Key components of swimming metabolism: standard metabolism (R(s)), active metabolism (R(a)) and absolute aerobic scope for activity (R(a)-R(s)) were determined for small age 0 year Atlantic cod Gadus morhua. Gadus morhua juveniles grew from 0.50 to 2.89 g wet body mass (M(WB)) over the experimental period of 100 days, and growth rates (G) ranged from 1.4 to 2.9% day(-1), which decreased with increasing size. Metabolic rates were recorded by measuring changes in oxygen consumption over time at different activity levels using modified Brett-type respirometers designed to accommodate the small size and short swimming endurance of small fishes. Power performance relationships were established between oxygen consumption and swimming speed measurements were repeated for individual fish as each fish grew. Mass-specific standard metabolic rates (RsMWB-1) were calculated from the power performance relationships by extrapolating to zero swimming speed and decreased from 7.00 to 5.77 micromol O(2) g(-1) h(-1), mass-specific active metabolic rates (RaMWB-1) were calculated from extrapolation to maximum swimming speed (U(max)) and decreased from 26.18 to 14.35 micromol O(2) g(-1) h(-1) and mass-specific absolute scope for activity was calculated as the difference between active and standard metabolism (RaMWB-1-RsMWB-1) and decreased from 26.18 to 14.35 micromol O(2) g(-1) h(-1) as M(WB) increased. Small fish with low R(s) had bigger aerobic scopes but, as expected, R(s) was higher in smaller fish than larger fish. The measurements and results from this study are unique as R(s), R(a) and absolute aerobic scopes have not been previously determined for small age 0 year G. morhua.

Effect of post-ethanol extraction sorghum silage as a forage source in growing and finishing diets on steer performance, carcass characteristics, and nutrient digestibility.

Two experiments evaluated the use of post-ethanol extraction sorghum silage as an alternative forage source in feedlot diets. Seventy-two crossbred steers (397 kg [SD 23]) were used to evaluate growth and carcass characteristics. Steers were blocked by BW into pens of 6 steers and randomly assigned to growing diets containing 40% (DM basis) sorghum silage (SS; 57.6% NDF) or grass hay (CON; 63.3% NDF) for 56 d ( = 6 pens per treatment). Within each treatment, steers transitioned to dry-rolled corn-based finishing diets (fed for 56 d) containing 6% effective NDF contributed by the forage source, resulting in forage inclusions of 16% for SS and 13.1% for CON, where forage replaced corn. A subsample of steers ( = 12 per treatment) housed in pens equipped with GrowSafe bunks were used for determination of growing phase diet total tract digestibility. From d 28 to 42, steers received titanium dioxide at approximately 10 g∙steer∙d, and fecal samples were collected on d 41 and 42. Fecal and total mixed ration samples were dried and ground for analysis of DM, OM, NDF, ADF, CP, ether extract (EE), and starch. Data were analyzed with the MIXED procedure of SAS, with fixed effects of treatment and block for performance and carcass data or treatment for digestibility data; significance was determined at ≤ 0.05 and tendencies at ≤ 0.10. Growing phase DMI and ADG did not differ due to treatment ( ≥ 0.19); however, SS-fed steers had improved G:F compared with CON-fed steers ( = 0.04). Finishing period ADG and G:F did not differ ( ≥ 0.15) between treatments, despite SS-fed steers having lesser ( = 0.008) DMI than CON-fed steers. No differences in DMI, ADG, or G:F over the whole trial were noted between treatments ( ≥ 0.12) nor were any carcass traits affected ( ≥ 0.23). During the digestibility assessment period, DMI was less ( = 0.003) in SS-fed steers. Growing phase total tract apparent digestibility of DM and starch did not differ ( ≥ 0.19) due to treatment; however, OM digestibility tended to be greater ( = 0.09) in SS-fed steers. Steers fed SS had greater ( ≤ 0.03) digestibility of EE, CP, NDF, and hemicellulose than CON-fed steers. However, CON-fed steers had greater ( < 0.0001) ADF digestibility than SS-fed steers. These data suggest that postextraction sorghum silage can be effectively used in feedlot diets as an alternative forage source.

Effect of trace mineral source on mineral status and performance of beef steers fed low- or high-sulfur diets.

A 2 × 2 factorial assessed the effect of trace mineral (TM) sources fed within low- or high-S diets on the mineral status and performance of cattle. Angus crossbred steers ( = 48; 6/pen) were blocked by BW (316 ± 16.6 kg), assigned to low-S (0.27%; LS) or high-S (0.54%; HS; added as CaSO) diets, and supplemented TM at 10 mg Cu, 30 mg Zn, and 20 mg Mn/kg DM from hydroxy (HYD; IntelliBond; Micronutrients USA LLC, Indianapolis, IN) or inorganic (sulfates; ING) sources ( = 12 steers/treatment). Steers were fed corn silage and corn-based diets via GrowSafe bunks in the growing period (GP; 84 d) and finishing period (FP; 77 d), respectively. Plasma and liver were collected at trial initiation and end of GP and FP for mineral concentrations. End of GP and FP red blood cell lysate superoxide dismutase (SOD) and Mn-SOD activity and liver glutathione concentrations were measured. Data were used as a 2 × 2 factorial using Proc Mixed of SAS (SAS Inst. Inc., Cary, NC) with initial plasma and liver status analyzed as covariates. High S decreased ( < 0.01) liver Cu and tended ( ≤ 0.10) to decrease plasma Cu concentrations. Liver Cu concentrations were lower in HYD than ING in the FP ( < 0.01). High S decreased ( = 0.04) GP plasma Zn concentrations and tended to decrease ( = 0.10) GP liver Zn. There were GP ( = 0.05) and FP ( = 0.02) S × TM effects for liver Mn concentrations where GP LS-HYD was greater than all other treatments, whereas FP LS-HYD was lower than HS-HYD and LS-ING and FP HS-ING was less than LS-ING. Glutathione, SOD, and Mn-SOD were not different ( ≥ 0.13) in the GP, but S × TM tended to affect FP Mn-SOD ( = 0.10), where LS-HYD tended to be lower than LS-ING. Oxidized glutathione in FP tended to be lower ( = 0.06) for HYD than ING. In the GP, there were S × TM effects on performance where LS-HYD had greater ADG and G:F ( ≤ 0.05) than HS-HYD, whereas LS and HS-ING were intermediate. For FP performance S × TM effects were noted where LS-HYD and HS-ING tended ( = 0.10) to gain more than HS-HYD and HS-HYD had lower G:F ( = 0.04) than HS-ING. There were no effects of S × TM on final BW, DMI, or ADG ( ≥ 0.11); however, HS-HYD had lower G:F than other treatments overall ( = 0.05). High S decreased back fat and yield grade ( = 0.03), and rib eye area was smaller for HYD than ING ( = 0.02). In this study HS decreased markers of Cu and Zn status, and differential effects of HYD vs. ING minerals were noted across dietary phases, although all steers maintained adequate TM status.

Influence of feed efficiency classification and growing and finishing diet type on meat tenderness attributes of beef steers.

Enhancing feed efficiency (FE) in cattle continues to be an important goal in the beef industry. Previous research suggests improving FE may alter calpain system activity, potentially having negative effects on meat tenderness. The objective of this study was to assess the potential influence of beef cattle FE on postmortem meat tenderness. During the growing phase, 181 crossbred steers were fed for 76 d at the University of Missouri on a whole shell corn-based diet (MU-Corn; = 90) or a roughage-based diet (MU-Rough; = 91). Within diet, steers were classified for FE based on residual feed intake (RFI) calculations. Within each growing phase diet, the 12 most feed efficient (HFE; average RFI -3.33 ± 0.77) and 12 least feed efficient (LFE; average RFI 2.90 ± 0.94) steers (48 steers total) were selected and shipped to Iowa State University for the finishing phase. Steers were fed in pens with GrowSafe bunks and equally assigned to a cracked corn-based finishing diet (ISU-Corn) or a byproduct-based finishing diet (ISU-Byp) for the 87-d finishing phase. After a 24-h chill, rib sections were collected from all carcasses and aged for 2 or 14 d prior to analysis of calpastatin activity and calpain 1 autolysis (d 2), troponin-T degradation (d 2 and 14), proximate composition (d 2), and Warner-Bratzler shear force (WBSF; d 14). Data were analyzed as a 2 × 2 × 2 factorial, with steer or steak as the experimental unit ( = 6 per treatment combination). There were no 3- or 2-way interactions ( ≥ 0.12) noted for any data, with the exception of steak lipid content, which tended ( = 0.08) to be affected by FE × Iowa State University diet. Steaks from LFE steers had greater lipid content compared with steaks from HFE steers within ISU-Byp, with no differences due to FE within ISU-Corn. Growing diet did not affect calpastatin activity, calpain 1 autolysis, or troponin T degradation ( ≥ 0.12); however, MU-Rough had greater WBSF than MU-Corn ( = 0.05). Day-2 calpastatin activity tended ( = 0.10) to be greater in steaks from HFE vs. LFE steers, although no differences due to FE classification were observed for calpain 1 protein, troponin-T degradation, or WBSF ( ≥ 0.13). Finishing diet did not affect calpastatin activity, calpain 1 autolysis, d-2 troponin-T degradation, or WBSF ( ≥ 0.24); however, d-14 troponin-T degradation was greater in ISU-Corn than in ISU-Byp ( = 0.005). In this study, using phenotypic extremes for FE revealed a tendency for greater calpastatin activity only in highly feed-efficient steers; however, these data indicate that high-fiber diets may negatively impact meat tenderness, and further work is needed to clarify the influence of diet type on parameters of meat tenderness.

Immunometabolic parameters in overweight dogs during weight loss with or without an exercise program.

The influence of physical activity on metabolic health in overweight dogs is unknown. This study was conducted to evaluate biomarkers of immunometabolic health in relation to changes in physical activity and adiposity. Client-owned overweight dogs participated in a 12-wk intervention based on caloric restriction combined with a training program (fitness and diet [FD] group, n = 8), or caloric restriction alone (diet-only [DO] group, n = 8). Physical activity was monitored by accelerometry. All dogs were fed the same diet and achieved similar weight loss. Fasting blood samples were collected before and after 6- and 12-wk intervention. Insulin resistance was evaluated from plasma insulin and C-peptide as well as homeostasis model assessment. Inflammation and dyslipidemia were evaluated from circulating leptin, adiponectin, C-reactive protein (CRP), monocyte chemoattractant factor-1 (MCP-1), interleukin-8 (IL-8), and cholesterol. Accelerometer counts in both groups were high compared with previous reports of physical activity in overweight dogs. No difference in blood parameters was evident between groups, evaluated by linear mixed-effects model (P > 0.05). Within the groups, the following changes were significant by t-test (P < 0.05): leptin decreased in both groups. Within the FD group, IL-8, MCP-1, and CRP decreased at 6 wk and IL-8 and cholesterol at 12 wk. Within the DO group, C-peptide and HOMA decreased at 6 wk and C-peptide at 12 wk. We conclude that, for both groups, weight loss resulted in minor indications of improved immunometabolic health, whereas this level of physical activity did not add further benefits.

Feeding a low manganese diet to heifers during gestation impairs fetal growth and development.

A study was conducted to examine the effects of low dietary Mn on growth performance of pregnant heifers and fetal development of their offspring. Twenty pregnant Angus (n = 9) and Simmental (n = 11) heifers averaging 17 mo of age and 447.6 kg of initial body weight were used in the 267-d study. Heifers were selected from a previous study examining the effects of supplemental Mn on growth and reproductive performance of heifers. Ten pregnant heifers per treatment from the control (analyzed at 15.8 mg of Mn/kg of DM) and supplemental Mn (50 mg/kg of DM) treatments were randomly selected at the conclusion of the previous study to continue on their respective dietary treatments through gestation and early lactation. Serum cholesterol for the 267-d period was not affected by treatment. Whole-blood Mn concentration of heifers on d 267 was not affected by treatment. Whole-blood Mn concentration at birth was lower in calves born to control heifers than in those born to supplemented heifers. Calves born to control heifers weighed less at birth than those born to heifers receiving supplemental Mn. Calves born to control heifers suffered from varying signs of Mn deficiency, including superior brachygnathism, unsteadiness, disproportionate dwarfism, and swollen joints. Results suggest that feeding gestating heifers a diet containing 16.6 mg of Mn/kg of DM is not adequate for proper fetal development. Supplementation of 50 mg of Mn/kg of DM to the control diet was sufficient to overcome any signs of Mn deficiency in calves.

Functionally deficient differentiation of HL-60 promyelocytic leukemia cells induced by phorbol myristate acetate.

The human promyelocytic leukemia cell line HL-60 undergoes terminal myeloid differentiation in vitro in response to a wide variety of chemicals. The tumor promoter phorbol myristate acetate induces these cells to develop macrophage-like morphology, adherence, and enzymatic characteristics. The present study confirms those observations and further documents the induction, by 16 nM phorbol myristate acetate, of 5'-nucleotidase activity, another human macrophage marker enzyme. However, more importantly, functional studies show that phorbol myristate acetate-induced HL-60 cells fail to increase above base line uninduced levels of hexose monophosphate shunt activity, superoxide generation, nitroblue tetrazolium reduction, bacterial ingestion, or complement secretion. These cells therefore possess some macrophage-like properties but do not meet several important functional criteria of macrophage identity.

Effects of increased inclusion of algae meal on finishing steer performance and carcass characteristics.

The deoiled residue from the production of heterotrophic microalgae can be combined with soyhulls to form a novel feedstuff called algae meal (ALG). To determine the effects of replacing corn in a finishing diet with ALG on growth, mineral status, carcass characteristics, and longissimus thoracis fatty acid profile, crossbred steers (168) were blocked by BW (432 ± 30.8 kg) into pens of 6 steers (7 pens per treatment). Pens received 1 of 4 diets: a corn-based control (CON), 14% ALG, 28% ALG (ALG28), and 42% ALG (ALG42). Corn was replaced by ALG on a DM basis. Steer BW were taken on d 0, 1, 28, 56, 74, 101, and 102, and steers were harvested on d 103. Pen was the experimental unit and DMI, ADG, and G:F data were analyzed as repeated measures. Two steers per pen were selected for sampling of blood and liver (d -1 and 96) and collection of rib steaks at harvest. There was a treatment by × time effect ( = 0.10) for overall DMI, where DMI linearly increased ( ≤ 0.008) across all time periods except Day 28 through, 56 when DMI was not different between ALG28 and ALG42. There was a treatment by time effect for ADG ( < 0.01), with ADG linearly decreasing ( ≤ 0.03) in the first and third month, not differing ( = 0.95) in the second month, and linearly increasing ( < 0.01) in the fourth month as ALG increased in the diet. Final BW and HCW did not differ ( ≥ 0.50) between CON- and ALG-fed cattle. There was a treatment × time effect for G:F ( < 0.01), with G:F linearly decreasing ( ≤ 0.01) in the first 3 mo as ALG increased in the diet, whereas G:F linearly increased ( < 0.01) in the fourth month. Based on steer performance, calculated dietary NEg linearly decreased ( < 0.01) as ALG increased in the diet. Yield grade linearly decreased ( = 0.02) and there was a tendency for dressing percent and 12th-rib back fat to linearly decrease ( ≤ 0.10) as ALG increased in the diet. Plasma Cu, Fe, and Mg concentrations were not different ( ≥ 0.31) in CON vs. ALG cattle; however, plasma Zn concentrations linearly increased ( = 0.03) as ALG increased in the diet. Total lipid, SFA, MUFA, and PUFA concentrations in the longissimus thoracis did not differ ( ≥ 0.13) between CON- and ALG-fed cattle. Interestingly, the atherogenic index linearly decreased ( < 0.01) as ALG increased in the diet. Algae meal may have a lesser energy value than corn; however, a minimal effect on carcass performance suggests ALG may serve as a potential replacement for corn in feedlot diets.

The effects of increasing supplementation of zinc-amino acid complex on growth performance, carcass characteristics, and inflammatory response of beef cattle fed ractopamine hydrochloride.

Forty-two Angus crossbred steers (380 ± 5.3 kg) were enrolled in a finishing study to evaluate the influence of a supplemental Zn amino-acid complex (ZnAA; Availa-Zn) on performance and carcass characteristics of finishing steers in combination with ractopamine hydrochloride (RAC). Steers were stratified by BW into 7 pens of 6 steers each, and individual feed intake was measured. Steers were assigned to 1 of 4 treatments for 86 d (pre-RAC period): a dry-rolled corn-based diet supplemented with 60 mg Zn/kg DM from ZnSO and no supplemental ZnAA (CON; analyzed 88 mg Zn/kg DM; = 6) or CON diet supplemented with 30 (Zn30; = 12), 60 (Zn60; = 12), or 90 (Zn90; = 11) mg Zn/kg DM from ZnAA. Day 86 BW and G:F displayed a quadratic tendency ( = 0.09) with Zn60 steers being greater than the other treatments. Plasma cyclic adenosine monophosphate tended to linearly increase with increasing ZnAA ( = 0.10). On d 88, 6 of 12 steers (one of the 2 pens) receiving supplemental ZnAA was randomly selected to be supplemented with RAC at 300 mg∙steer∙d for the final 28 d of the experiment (RAC period). This created 7 final treatments: CON: no supplemental ZnAA, no RAC ( = 5); Zn30: Zn30, no RAC ( = 5); Zn30R: Zn30 + RAC ( = 6); Zn60: Zn60, no RAC ( = 6); Zn60R: Zn60 + RAC ( = 6); Zn90: Zn90, no RAC ( = 5); and Zn90R: Zn90 + RAC ( = 6). During the RAC period, as supplemental ZnAA increased within RAC-supplemented treatments, there was a linear increase in final BW, ADG, and G:F ( < 0.05). However, there was no effect of supplemental ZnAA on BW, ADG, or G:F during this period in non-RAC fed steers ( ≥ 0.44). Day 111 plasma Cu was increased, plasma Fe decreased, and leukocyte counts and serum interleukin-8 concentrations were greater ( < 0.05) in RAC-fed steers suggesting that RAC may elicit a mild inflammatory response. There was a tendency for increasing Zn supplementation to decrease plasma haptoglobin within RAC-fed steers ( = 0.07), suggesting that Zn may alter the inflammatory response. Overall, Zn60 improved growth performance during the pre-RAC period. Zinc supplemented as ZnAA appears to improve growth in combination with RAC supplementation, suggesting that Zn may enhance or support the biological function of RAC. Additionally, these results indicate that feeding RAC impacts trace mineral status, and potentially causes a non-specific inflammatory response, but further research is required to define this response.

Relationship between antioxidant capacity, oxidative stress, and feed efficiency in beef steers.

Feed efficiency (FE) can vary between individuals but sources of variation are not well characterized. Oxidative stress is among the biological mechanisms believed to contribute to variation. The objective of this study was to evaluate the relationship between FE, antioxidant activity, and oxidative stress in feedlot steers representing phenotypic extremes for FE. Crossbred beef steers ( = 181) fed 70-d growing phase (GP) whole-shell corn-based (G-Corn) or rye baleage and soybean hull-based (G-Rough) diets in GrowSafe bunks at the University of Missouri were shipped to Iowa State University where the 12 most feed efficient (HFE) and 12 least feed efficient (LFE) steers from each diet (n = 48; 467 kg [SD 51]) were selected for evaluation. Steers received diets similar to GP diets, and 3 d after arrival, blood was sampled to evaluate antioxidant activity and oxidative stress markers for the GP following transit. Steers were transitioned to finishing phase (FP) cracked corn-based (F-Corn) or dried distillers' grains and soybean hull-based (F-Byp) diets, and on FP d 97, blood samples for the FP were collected. Data for the GP were analyzed as a 2 × 2 factorial, and data for the FP were analyzed as a 2 × 2 × 2 factorial using PROC MIXED of SAS. No GP diet × FP diet, FP diet × FE group, or 3-way interactions were noted ( ≥ 0.11) for FP measures. Steers fed the G-Rough diet had greater ( = 0.04) GP plasma protein carbonyl concentrations. During the GP, HFE steers had greater ( ≤ 0.04) protein carbonyl and ratio of oxidized:reduced blood lysate glutathione concentrations than LFE steers. There were GP diet × FE group interactions ( ≤ 0.03) during the GP and FP. During the GP, total blood lysate superoxide dismutase (SOD) activity was greater ( ≤ 0.03) in G-Rough/LFE steers than in G-Rough/HFE and G-Corn/LFE steers; G-Corn/HFE steers were intermediate. The G-Rough/LFE steers had greater ( < 0.04) glutathione peroxidase (GPX) activity than other groups and greater ( = 0.03) plasma malondialdehyde concentrations than G-Corn/LFE steers. During the FP, the G-Rough/LFE steers had greater ( ≤ 0.04) GPX activity than G-Rough/HFE and G-Corn/LFE steers; G-Corn/HFE steers were intermediate. The F-Byp diet had greater ( < 0.01) protein carbonyl than the F-Corn diet, and no other FP diet effects were noted ( ≥ 0.3) for any FP measures. The GP diet and FE groups had stronger relationships with antioxidant activity and oxidative stress markers measured for the GP than for the FP. Overall, antioxidant activity may play a role in FE as LFE steers, driven largely by G-Rough/LFE steers, had greater SOD activity and GPX activity than HFE steers, potentially using a greater proportion of energy otherwise available for tissue accretion.

The influence of supplemental Zn-amino acid complex and ractopamine hydrochloride feeding duration on growth performance and carcass characteristics of finishing beef cattle.

Previous research indicates that finishing steer ADG and G:F increases linearly with increasing dietary Zn-amino acid complex (ZnAA) supplementation in cattle fed ractopamine hydrochloride (RAC). The objective of this study was to determine the influence of supplemental Zn-amino acid complex on growth performance and carcass characteristics of finishing steers fed RAC for 0, 28, or 42 d prior to harvest. This study was organized as 2 groups (GRP) of steers fed concurrently, for 91 (GRP 1) or 84 d (GRP 2). A total of 324 steers (463 ± 23.4 kg) were fed a corn-based finishing diet supplemented with 60 mg Zn/kg diet DM (as ZnSO). Steers were blocked by weight to pens of 6 steers, and assigned to receive either 0 (CON) or 60 mg supplemental Zn/kg DM from ZnAA ( = 27 pens per treatment). Receiving ZnAA for 49 (GRP 1) or 42 d (GRP 2) prior to start of RAC feeding had no impact on growth of steers ≥ 0.19). Forty-two d prior to harvest, pens were equally assigned within CON or ZnAA treatments to receive RAC at 300 mg∙steer∙d for 0 (NoRAC), 28 (28RAC), or 42 d (42RAC) prior to harvest, creating 6 final treatments ( = 9 pens per treatment). All steers within a GRP were harvested on the same day. Pen was the experimental unit, and the statistical model included the fixed effects of ZnAA, RAC, and block nested within GRP, and the random effect of pen. Ractopamine hydrochloride supplementation increased carcass-adjusted ADG, final BW, HCW, and ribeye area ( ≤ 0.007). There was an effect of ZnAA within 28RAC and 42RAC where carcass-adjusted ADG ( ≤ 0.10), and final BW and HCW ( ≤ 0.05) were greater in ZnAA supplemented vs. CON steers, and 28RAC steers supplemented with ZnAA had improved overall carcass-adjusted G:F relative to CON steers ( = 0.04). However, when steers did not receive RAC there was no effect of ZnAA on final BW, ADG, or HCW ( ≥ 0.78). Additionally, ZnAA supplementation had no effect on the difference in performance between steers supplemented with RAC for 28 vs. 42 d ( 0.21). In conclusion, under the conditions of this study supplemental ZnAA did not prevent the diminished response to RAC as days on RAC increased from 28 to 42. However, there appears to be a synergistic effect of ZnAA on RAC-induced cattle growth, as supplementing 60 mg Zn/kg DM from ZnAA to cattle fed RAC improved overall growth and HCW.

Influence of feed efficiency classification on diet digestibility and growth performance of beef steers.

The diet digestibility and feed efficiency (FE) relationship is not well characterized in cattle. The study objective was to determine effects of growing phase FE and diet as well as finishing phase diet on diet digestibility and finishing phase FE. Two groups, totaling 373 crossbred steers, were fed for 70 d at the University of Missouri for the growing phase and then shipped to Iowa State University (ISU) for finishing. GrowSafe feed bunks were used during both the growing and the finishing phases. Steers were fed either growing phase whole shell corn (G-Corn) or growing phase roughage-based (G-Rough) diets. Within each group, the 12 greatest and 12 least feed efficient steers from each growing diet ( = 96 total; 48 steers/group; 488 ± 5 kg) were selected for further evaluation. At ISU, steers were fed an average of 10 g TiO/steer daily in receiving phase diets similar to growing diets for 15 d, with fecal grab samples collected on d 14 and 15 to determine diet DM digestibility during receiving (GDMdig). For finishing, steers were transitioned to byproduct-based diets (F-Byp) or corn-based diets (F-Corn) with 12 steers per growing-finishing diet combination per group. Optaflexx (200 mg/d) was fed for 28 d before harvest, and the TiO protocol was repeated immediately before introducing Optaflexx to determine diet DM digestibility during finishing (FDMdig). Data from the 2 groups (96 steers) were pooled, and steers were ranked by growing phase G:F and then classified as the 24 greatest feed efficient (HFE) or 24 least feed efficient (LFE) steers from each growing diet. Data were analyzed using PROC MIXED of SAS with group applied as a fixed effect. There was a positive correlation between GDMdig and FDMdig for steers fed nutritionally similar diets during both feeding phases, G-Rough/F-Byp steers ( = 0.68, < 0.01) and G-Corn/F-Corn steers ( = 0.49, = 0.02), but a negative correlation for G:F between phases in G-Rough/F-Corn steers ( = -0.57, < 0.01). Finishing G:F was greater in HFE steers versus LFE steers ( = 0.04), but there was no difference ( ≥ 0.5) in GDMdig or FDMdig due to FE classification. There was a positive correlation for DM digestibility between feeding phases when steers were grown and finished on similar diets. Overall, FE was repeatable but was negatively correlated between phases when steers were roughage grown and corn finished, reinforcing the idea that cattle should be FE tested using diet types similar to the production environment of interest.