A meta-analysis of zilpaterol and ractopamine effects on feedlot performance, carcass traits and shear strength of meat in cattle

Resting and activated bovine neutrophils and eosinophils differ in their responses to adrenergic agonists

Polymorphonuclear cells (PMN) provide a rapid response to infection and tissue damage and stress can modify these critical innate immune defences. The study of adrenergic receptor (AR) expression and function in bovine PMNs is limited but both neutrophils and eosinophils express numerous AR genes but differ significantly in their expression of individual AR genes. A flow cytometric technique was developed to differentiate between bovine neutrophils and eosinophils so both neutrophil and eosinophil responses to adrenergic agonists could be analysed. Neutrophils and eosinophils displayed significantly different changes in CD11b, L-selectin, and CD44 expression when activated by bovine serum opsonized zymosan and recombinant bovine interferon gamma. The responses of activated and resting neutrophils and eosinophils were then compared following stimulation with endogenous adrenergic agonists, epinephrine (E) norepinephrine (NE), and synthetic agonists targeting α1-, α2-, or β-ARs. Both resting and activated neutrophils and eosinophils displayed differences in iROS, CD44, and L-selectin expression following stimulation with E and NE. Resting neutrophils displayed pro-inflammatory responses to both E and NE, while resting eosinophils displayed a pro-inflammatory response to only NE. No single synthetic adrenergic agonist fully recapitulated responses observed with either E or NE and responses to adrenergic agonists were dose-dependent. In conclusion, bovine eosinophils and neutrophils responded to multiple adrenergic agonists by altering expression of proteins involved in immune surveillance and pro-inflammatory responses. Significant differences in neutrophil and eosinophil responses to adrenergic agonists are consistent with their differences in AR gene expression. This highlights the importance of analysing separately these two PMN subpopulations when investigating the effects of either endogenous or synthetic AR agonists.

Impact of Humectants on Physicochemical and Functional Properties of Jerky: A Meta-Analysis

This study aimed to determine the effects of humectants on moisture content, water activity, tenderness, color, microbiological analysis, protein denaturation, and oxidation of jerky. A thorough search for papers published in scientific journals that examined the impacts of humectants on jerky was carried out using Web of Science, Google Scholar, PubMed, and Science Direct. Only 14 studies matched inclusion requirements. They were used in the meta-analysis to synthesise quantitative findings. In the current investigation, jerky produced with beef, poultry, goat, or pork was used. The standardised mean difference (SMD) between treatments with humectants and controls was examined to investigate the effects of humectants using random-effects models. Heterogeneity was investigated using meta-regression. A subgroup analysis was carried out for significant factors. Results revealed that the addition of humectants had no significant impact on water activity, pH, fat, ash, CIE L*, or CIE a* (p>0.05). However, humectant addition significantly increased moisture (SMD=1.28, p<0.05), CIE b* (SMD=1.67, p<0.05), and overall acceptability (SMD=1.73, p<0.05). It significantly decreased metmyoglobin (SMD=-0.96, p<0.05), shear force (SMD=-0.84, p<0.05), and protein (SMD=-1.61, p<0.05). However, it was difficult to get a firm conclusion about how humectants affected the myofibrillar fragmentation index, total plate count, and 2-thiobarbituric acid-reactive substances because there were fewer than ten studies. To sum up, the proper use of humectants in jerky demands careful attention to both type and quantity, needing a delicate balancing act with other contributing factors.

Vitamins and Trace Minerals in Ruminants: Confinement Feedlot

Trace minerals and vitamins are essential for optimizing feedlot cattle growth, health, and carcass characteristics. Understanding factors that influence trace mineral and vitamin absorption and metabolism is important when formulating feedlot cattle diets. Current feedlot industry supplementation practices typically exceed published trace mineral requirements by a factor of 2 to 4. Therefore, the intent of this review is to briefly discuss the functions of trace minerals and vitamins that are typically supplemented in feedlot diets and to examine the impact of dose of trace mineral or vitamin on growth performance, health, and carcass characteristics of feedlot cattle.

Meta-Regression Analysis of Relationships between Fibre Type and Meat Quality in Beef and Pork-Focus on Pork

This meta-regression analysis was conducted to identify the relationship between fibretype cross-sectional area (CSA) and frequency (%) and meat quality traits, especially tenderness (sensory and Warner-Bratzler Shear Force, WBSF). Literature searches were conducted using specific keywords which resulted in 32 peer-reviewed manuscripts that contained averages and correlation coefficients for fibre type (frequency and CSA) and quality traits of longissimus muscle for beef and pork (7 and 25 studies respectively). Correlations were analysed in meta-regression using R-Studio and linear regression was also conducted. For the combined beef and pork analysis, only pH, WBSF, and drip loss were associated with fibre type frequency and CSA (p < 0.05 for all). Limiting the analysis to pork, the key results were frequency of type I fibres were associated with decreased drip loss, increased cook loss, decreased lightness (L*) and increased sensory tenderness whereas frequency of type IIb fibres were associated with increased drip loss (p < 0.05 for all). In addition, the CSA of type I and IIb fibres was associated with colour traits lightness and redness (p < 0.05 for all). Future research should focus on fibre type across breeds and muscles to further understand the impacts of fibre type frequency and CSA on quality.

Effects of Supplementation with Bee Pollen and Propolis on Growth Performance and Serum Metabolites of Rabbits: A Meta-Analysis

The objective of this study was to evaluate the effects of bee pollen (BP) and propolis (PRO) supplementation on rabbits' productive performance and serum metabolites through a meta-analysis. Sixteen peer-reviewed publications were included in the data set. The rabbit strains used in the studies included in the data set were New Zealand White, V-line, Rex, and V-line crosses. Weighted mean differences (WMD) between treatments supplemented with BP or PRO and control treatments were used to assess the magnitude of the effect. BP supplementation decreased (p < 0.001) daily feed intake (DFI) and feed conversion ratio (FCR); however, increased (p < 0.001) average daily gain (ADG) and hot carcass yield (HCY). PRO supplementation reduced DFI (p = 0.041) and FCR (p < 0.001), and increased ADG (p < 0.001) and HCY (p = 0.005). In blood serum, BP supplementation increased total antioxidant capacity (TAC; p = 0.002) and decreased serum creatinine concentration (p = 0.049). Likewise, decreased serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and malondialdehyde (MDA) were detected in response to BP supplementation (p < 0.05). PRO supplementation increased the TAC in blood serum (p = 0.018); however, decreased serum concentrations of AST, ALT, and MDA were observed (p < 0.05). In conclusion, BP or PRO supplementation can be used as a natural growth promoter in rabbits, and both can also improve rabbits' antioxidant status. However, BP or PRO supplementation does not affect rabbits' renal or hepatic health status.

Meta-analysis of flavonoids use into beef and dairy cattle diet: Performance, antioxidant status, ruminal fermentation, meat quality, and milk composition

The objective of this study was to evaluate the effects of dietary supplementation with flavonoids (FLAs) on animal performance, diet digestibility, antioxidant status in blood serum, rumen parameters, meat quality, and milk composition in beef and dairy cattle through a meta-analysis. Thirty-six peer-reviewed publications were included in the data set. The weighted mean differences (WMD) between the FLAs treatments and the control treatment were used to assess the effect size. Dietary supplementation with FLAs decreased feed conversion ratio (WMD = -0.340 kg/kg; p = 0.050) and increased (p < 0.05) dry matter intake (WMD = 0.191 kg/d), dry matter digestibility (WMD = 15.283 g/kg of DM), and daily weight gain (WMD = 0.061 kg/d). In blood serum, FLAs supplementation decreased the serum concentration of malondialdehyde (WMD = -0.779 nmol/mL; p < 0.001) and increased (p < 0.01) the serum concentration of superoxide dismutase (WMD = 8.516 U/mL), glutathione peroxidase (WMD = 12.400 U/mL) and total antioxidant capacity (WMD = 0.771 U/mL). A higher ruminal propionate concentration (WMD = 0.926 mol/100 mol; p = 008) was observed in response to FLAs supplementation. In meat, the dietary inclusion of FLAs decreased (p < 0.05) shear force (WMD = -1.018 kgf/cm²), malondialdehyde content (WMD = -0.080 mg/kg of meat), and yellowness (WMD = -0.460). Supplementation with FLAs decreased milk somatic cell count (WMD = -0.251 × 103 cells/mL; p < 0.001) and increased (p < 0.01) milk production (WMD = 1.348 kg/d), milk protein content (WMD = 0.080/100 g) and milk fat content (WMD = 0.142/100 g). In conclusion, dietary supplementation with FLAs improves animal performance and nutrient digestibility in cattle. In addition, FLAs improve the antioxidant status in blood serum and the quality of meat and milk.

Ractopamine and age alter oxygen use and nitrogen metabolism in tissues of beef steers

The objective was to quantify the effects of age and ractopamine (RAC) on whole body oxygen consumption and Leu flux, and oxygen flux and metabolism of nitrogenous compounds by the portal-drained viscera (PDV), liver, and hindquarters (HQ) of steers. Multicatheterized steers were fed a high energy diet every 2 h in 12 equal portions. Five younger steers (body weight, [BW] = 223 ± 10.1 kg) were 6 mo old and five older steers (BW = 464 ± 16.3 kg) were 14 mo old. Treatments were control (Cont) or 80 mg RAC per kg diet in a crossover design. Nitrogen (N) balance was measured on day 9 to 13. Whole body oxygen consumption and net flux were measured on day 11 and day 13, and net flux of N variables, Phe and Leu kinetics were measured on day 13. Whole body oxygen consumption increased (P < 0.05) in response to RAC in older but not younger steers. Retained N was greater (P = 0.009) for younger than older steers and increased (P = 0.010) with RAC in both ages of steers. Nitrogen retained as a percentage of N apparently absorbed increased (P < 0.05) in the older steers but not the younger steers in response to RAC. Oxygen uptake was greater (P < 0.05) in PDV, liver, and total splanchnic tissues in the younger steers and there was no response to RAC. In contrast, oxygen uptake in HQ increased (P < 0.05) with RAC in the older but not the younger steers. Concentration and net PDV release of α-amino N (AAN) were not affected by age or RAC. Uptake of AAN by liver decreased with RAC (P = 0.001). Splanchnic release of AAN was greater in younger steers (P = 0.020) and increased (P = 0.024) in response to RAC. For HQ tissues, uptake (P = 0.005) and extraction (P = 0.005) of AAN were lesser in older than younger steers and both increased (P = 0.001) in response to RAC. Based on Phe kinetics in HQ, RAC increased (P < 0.05) protein synthesis in older steers but not in younger steers. In contrast, protein breakdown decreased (P < 0.05) in response to RAC in younger steers. In response to RAC, protein degradation was less (P < 0.05) in younger than older steers. Based on Leu kinetics, whole body protein synthesis was greater in the younger steers (P = 0.022) but not altered in response to RAC. Ractopamine enhanced lean tissue growth by increasing supply of AAN to peripheral tissues and altering protein metabolism in HQ. These metabolic responses are consistent with established responses to RAC in production situations.

Direct and indirect nutritional factors that determine reproductive performance of heifer and primiparous cows

Pregnancy rate is a major determinant of population dynamics of wild ungulates and of productivity of livestock systems. Allocation of feeding resources, including stocking rates, prior to and during the breeding season is a crucial determinant of this vital rate. Thus, quantification of effects and interaction among multiple factors that affect pregnancy rate is essential for management and conservation of pasture-based systems. Pregnancy rate of 2982 heifers and primiparous cows was studied as a function of animal category, average daily gain during the breeding season, stocking rate, pasture type and body weight at the beginning of the breeding season. Data were obtained from 43 experiments conducted in commercial ranches and research stations in the Pampas region between 1976 and 2015. Stocking rate ranged from 200 to 464 kg live weight ha-1, which brackets values for most of the grazinglands in similar regions. Age at breeding was 14-36 months (24.6±7.5 months); initial breeding weights were 129-506 kg and 194-570 kg for heifers and primiparous cows. Pregnancy rate was modeled with an apriori set of explanatory variables where proximate variables (breed, body weight at start of breeding, weight gain during breeding and category) were included first and subsequently modeled as functions of other variables (pasture type, supplementation and stocking rate). This modeling approach allowed detection of direct and indirect effects (through nutrition and body weight) of factors that affect pregnancy rate. Bos taurus breeds (N = 1058) had higher pregnancy rate than B. Taurus x B. indicus crossbreed (N = 1924) females. Pregnancy rate of heifers and primiparous cows grazing in natural grasslands decreased with increasing stocking rate, but no effect of stocking rate was detected in cultivated and improved pastures. Pregnancy rate increased with increasing average daily gain during the breeding season. Use of cultivated or improved natural pastures promotes higher pregnancy rate, as well as allows an increase in stocking rate at the regional level. Body weight at the start of the breeding season is the primary determinant of pregnancy rates in heifer and primiparous cows.

Organocatalytic Asymmetric Synthesis of Bridged Tetrahydrobenzo[b]azepines/oxepines

The asymmetric synthesis of bridged tetrahydrobenzo[b]azepine and oxepine derivatives through chiral Brønsted acid catalyzed asymmetric aza-Piancatelli rearrangement/Michael addition sequence has been developed. The reaction proceeds under mild reaction conditions to afford the final bridged cyclic products in good yields with excellent enantio- and diastereoselectivities.

Ractopamine at the Center of Decades-Long Scientific and Legal Disputes: A Lesson on Benefits, Safety Issues, and Conflicts

Ractopamine (RAC) is a synthetic phenethanolamine, β–adrenergic agonist used as a feed additive to develop leanness and increase feed conversion efficiency in different farm animals. While RAC has been authorized as a feed additive for pigs and cattle in a limited number of countries, a great majority of jurisdictions, including the European Union (EU), China, Russia, and Taiwan, have banned its use on safety grounds. RAC has been under long scientific and political discussion as a controversial antibiotic as a feed additive. Here, we will present significant information on RAC regarding its application, detection methods, conflicts, and legal divisions that play a major role in controversial deadlock and why this issue warrants the attention of scientists, agriculturists, environmentalists, and health advocates. In this review, we highlight the potential toxicities of RAC on aquatic animals to emphasize scientific evidence and reports on the potentially harmful effects of RAC on the aquatic environment and human health.

Short Communication: Beta-adrenergic agonists alter oxidative phosphorylation in primary myoblasts

Beta-adrenergic agonists (β-AAs) are widely used supplements in beef and pork production to improve feed efficiency and increase lean muscle mass, yet little is known about the molecular mechanism by which β-AAs achieve this outcome. Our objective was to identify the influence of ractopamine HCl and zilpaterol HCl on mitochondrial respiratory activity in muscle satellite cells isolated from crossbred beef steers (N = 5), crossbred barrows (N = 2), Yorkshire-cross gilts (N = 3), and commercial weather lambs (N = 5). Real-time measurements of oxygen consumption rates (OCRs) were recorded using extracellular flux analyses with a Seahorse XFe24 analyzer. After basal OCR measurements were recorded, zilpaterol HCl, ractopamine HCl, or no β-AA was injected into the assay plate in three technical replicates for each cell isolate. Then, oligomycin, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone, and rotenone were injected into the assay plate sequentially, each inducing a different cellular state. This allowed for the measurement of OCR at these states and for the calculation of the following measures of mitochondrial function: basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, adenosine triphosphate (ATP)-linked respiration, and spare respiratory capacity. Incubation of bovine cells with either zilpaterol HCl or ractopamine HCl increased maximal respiration (P = 0.046) and spare respiratory capacity (P = 0.035) compared with non-supplemented counterparts. No difference (P > 0.05) was observed between zilpaterol HCl and ractopamine HCl for maximal respiration and spare respiratory capacity in bovine cell isolates. No measures of mitochondrial function (basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, ATP-linked respiration, and spare respiratory capacity) were altered by β-AA treatment in ovine or porcine cells. These findings indicate that β-AAs in cattle may improve the efficiency of oxidative metabolism in muscle satellite cells by modifying mitochondrial respiratory activity. The lack of response by ovine and porcine cells to β-AA incubation also demonstrates differing physiological responses to β-AA across species, which helps to explain the variation in its effectiveness as a growth supplement.

Environmental performance of commercial beef production systems utilizing conventional productivity-enhancing technologies

The objective of this study was to evaluate the effects of using conventional productivity-enhancing technologies (PETs) with or without other natural PETs on the growth performance, carcass traits and environmental impacts of feedlot cattle. A total of 768 cross-bred yearling steers (499 ± 28.6 kg; n = 384) and heifers (390 ± 34.9 kg; n = 384) were offered a barley grain-based basal diet and divided into implanted or non-implanted groups. Steers were then allocated to diets that contained either: (i) no additive (control); natural feed additives including (ii) fibrolytic enzymes (Enz), (iii) essential oil (Oleo), (iv) direct fed microbial (DFM), (v) DFM + Enz + Oleo combination; conventional feed additives including (vi) Conv (monensin, tylosin, and beta-adrenergic agonists [βAA]); or Conv with the natural feed additives including (vii) Conv + DFM + Enz; (viii) Conv + DFM + Enz + Oleo. Heifers received one of the first three dietary treatments or the following: (iv) probiotic (Citr); (v) Oleo + Citr; (vi) Melengesterol acetate (MGA) + Oleo + βAA; (vii) Conv (monensin, tylosine, βAA, and MGA); or (viii) Conv + Oleo (ConvOleo). Data were used to estimate greenhouse gas (GHG) and ammonia (NH3) emissions, as well as land and water use. Implant and Conv-treated cattle exhibited improvements in growth and carcass traits as compared to the other treatments (P &lt; 0.05). Improvements in the performance of Conv-cattle illustrated that replacing conventional feed additives with natural feed additives would increase both the land and water required to satisfy the feed demand of steers and heifers by 7.9% and 10.5%, respectively. Further, GHG emission intensity for steers and heifers increased by 5.8% and 6.7%, and NH3 emission intensity by 4.3% and 6.7%, respectively. Eliminating the use of implants in cattle increased both land and water use by 14.6% and 19.5%, GHG emission intensity by 10.5% and 15.8%, and NH3 emission intensity by 3.4% and 11.0% for heifers and steers, respectively. These results demonstrate that use of conventional PETs increased animal performance while reducing environmental impacts of beef production. Restricting use would increase the environmental footprint of beef produced for both domestic and international markets.

A Meta-Analysis of Essential Oils Use for Beef Cattle Feed: Rumen Fermentation, Blood Metabolites, Meat Quality, Performance and, Environmental and Economic Impact

The objective of this study was to see how dietary supplementation with essential oils (EOs) affected rumen fermentation, blood metabolites, growth performance and meat quality of beef cattle through a meta-analysis. In addition, a simulation analysis was conducted to evaluate the effects of EOs on the economic and environmental impact of beef production. Data were extracted from 34 peer-reviewed studies and analyzed using random-effects statistical models to assess the weighted mean difference (WMD) between control and EOs treatments. Dietary supplementation of EOs increased (p < 0.01) dry matter intake (WMD = 0.209 kg/d), final body weight (WMD = 12.843 kg), daily weight gain (WMD = 0.087 kg/d), feed efficiency (WMD = 0.004 kg/kg), hot carcass weight (WMD = 5.45 kg), and Longissimus dorsi muscle area (WMD = 3.48 cm2). Lower (p < 0.05) ruminal concentration of ammonia nitrogen (WMD = −1.18 mg/dL), acetate (WMD = −4.37 mol/100 mol) and total protozoa (WMD = −2.17 × 105/mL), and higher concentration of propionate (WMD = 0.878 mol/100 mol, p < 0.001) were observed in response to EOs supplementation. Serum urea concentration (WMD = −1.35 mg/dL, p = 0.026) and haptoglobin (WMD = −39.67 μg/mL, p = 0.031) were lower in cattle supplemented with EOs. In meat, EOs supplementation reduced (p < 0.001) cooking loss (WMD = −61.765 g/kg), shear force (WMD = −0.211 kgf/cm2), and malondialdehyde content (WMD = −0.040 mg/kg), but did not affect pH, color (L* a* and b*), or chemical composition (p > 0.05). Simulation analysis showed that EOs increased economic income by 1.44% and reduced the environmental footprint by 0.83%. In conclusion, dietary supplementation of EOs improves productive performance and rumen fermentation, while increasing the economic profitability and reducing the environmental impact of beef cattle. In addition, supplementation with EOs improves beef tenderness and oxidative stability.

Effects of increasing supplemental zinc in beef feedlot steers administered a steroidal implant and beta agonist

Ninety-two Angus-crossbred steers (424 ± 28.3 kg initial body weight) were used in a 98-d study to assess the effects of increasing Zn supplementation on cattle performance, liver and plasma trace mineral concentrations, blood metabolites, and carcass characteristics. All steers were implanted with a Component TE-200 (200 mg trenbolone acetate + 20 mg estradiol; Elanco Animal Health, Greenfield, IN) on d 0 and fed 300 mg‧steer⁻¹‧d⁻¹ of ractopamine hydrochloride (Zoetis, Parsippany, NJ) from d 70 to 98. Cattle were fed via GrowSafe bunks (GrowSafe Systems Ltd., Airdrie, AB, Canada), and steer served as the experimental unit (n = 22 or 23 steers/treatment). Supplemental Zn was administered through the diet at 0, 100, 150, or 180 mg Zn/kg on a dry matter basis from ZnSO₄ (Zn0, Zn100, Zn150, or Zn180, respectively). Cattle were weighed on d −1, 0, 9/10, 20, 41, 59, 69, 70, 78/79, 97, and 98. Blood was collected on d 0, 9/10, 69, 78/79, and 97, and liver biopsies on d 9/10 and 78/79 (n = 12 steers/treatment). Data were analyzed as a complete randomized design. Contrast statements were formed to test the linear, quadratic, and cubic effects of Zn supplementation and test Zn0 vs. Zn supplementation. Day 10 and 70 body weight (BW) and d 0 to 10 and 0 to 70 average daily gain were linearly increased with Zn supplementation (P ≤ 0.05), and greater for Zn supplemented steers (P ≤ 0.03). No effects of Zn supplementation were observed on final BW, dressing percentage, ribeye area, 12th rib fat, or marbling (P ≥ 0.11). Hot carcass weight tended to be 7 kg greater for Zn supplemented steers than Zn0 (P = 0.07), and yield grade linearly increased with increasing Zn supplementation (P = 0.02). Day 10 liver Mn concentrations tended to quadratically decrease (P = 0.08) with increasing Zn supplementation, though d 79 liver Mn concentrations and arginase activity were not influenced by Zn (P ≥ 0.28). Day 10 liver arginase activity tended to be (r = 0.27; P = 0.07) and d 10 serum urea nitrogen was correlated with d 10 liver Mn (r = 0.55; P < 0.0001). Zinc supplementation linearly increased d 10 liver Zn and d 10, 69, 79, and 97 plasma Zn concentrations (P ≤ 0.05). A cubic effect of Zn was observed on d 79 liver Zn (P = 0.01) with lesser liver Zn in Zn0 and Zn150 steers. These data suggest increasing dietary Zn improves growth directly following the administration of a steroidal implant and that steroidal implants and beta agonists differ in their effects on protein metabolism.

Transcriptome analyses indicate that heat stress-induced inflammation in white adipose tissue and oxidative stress in skeletal muscle is partially moderated by zilpaterol supplementation in beef cattle

Heat stress (HS) triggers oxidative stress, systemic inflammation, and disrupts growth efficiency of livestock. β-adrenergic agonists supplemented to ruminant livestock improve growth performance, increase skeletal muscle mass, and decrease carcass fat. The objective of this study was to understand the independent and interacting effects of HS and zilpaterol hydrochloride (ZH) supplementation on the transcriptome of subcutaneous white adipose tissue and the longissimus dorsi muscle in steers. Twenty-four Red Angus-based steers were assigned to thermoneutral (TN; Temperature Humidity Index [THI] = 68) or HS (THI = 73-85) conditions and were not supplemented or supplemented with ZH (8.33 mg/kg/d) for 21 d in a 2 × 2 factorial. Steers in the TN condition were pair-fed to the average daily feed intake of HS steers. RNA was isolated from adipose tissue and skeletal muscle samples collected via biopsy on 3, 10, and 21 d and sequenced using 3' Tag-Seq to an achieved average depth of 3.6 million reads/sample. Transcripts, mapped to ARS-UCD1.2, were quantified. Differential expression (DE) analyses were performed in DESeq2 with a significance threshold for false discovery rate of 0.05. In adipose, 4 loci (MISP3, APOL6, SLC25A4, and S100A12) were DE due to ZH on day 3, and 2 (RRAD, ALB) were DE due to the interaction of HS and ZH on day 10 (Padj < 0.05). In muscle, 40 loci (including TENM4 and OAZ1) were DE due to ZH on day 10, and 6 loci (HIF1A, LOC101903734, PDZD9, HNRNPU, MTUS1, and TMCO6) were DE due to environment on day 21 (Padj < 0.05). To explore biological pathways altered by environment, supplement, and their interaction, loci with DE (Praw < 0.05) were evaluated in Ingenuity Pathway Analysis. In adipose, 509 pathways were predicted to be altered (P < 0.01): 202 due to HS, 126 due to ZH, and 181 due to the interaction; these included inflammatory pathways predicted to be upregulated due to HS but downregulated due to the interaction of HS and ZH. In muscle, 113 pathways were predicted to be altered (P < 0.01): 23 due to HS, 66 due to ZH, and 24 due to the interaction of HS and ZH. Loci and pathway data in muscle suggest HS induced oxidative stress and that the stress response was moderated by ZH. Metabolic pathways were predicted to be altered due to HS, ZH, and their interaction in both tissues. These data provide evidence that HS and ZH interact to alter expression of genes in metabolic and immune function pathways and that ZH moderates some adverse effects of HS.

Effect of trenbolone acetate, melengestrol acetate, and ractopamine hydrochloride on the growth performance of beef cattle

The effect of trenbolone acetate + estradiol (TBA) implants, melengestrol acetate (MGA), and ractopamine hydrochloride + TBA (RAC + TBA) on growth performance and carcass characteristics in beef cattle (n = 680; 279 ± 10.1 kg) fed barley grain/corn silage was examined in a 4 yr study (four pens per treatment per year; 262 ± 8 d feeding period). In the first 2 yr, treatments were (1) control heifers (H-CON; no growth promoters), (2) TBA-implanted heifers (H-TBA), (3) MGA heifers (H-MGA), (4) control steers (S-CON; no growth promoters), and (5) TBA-implanted steers (S-TBA). A sixth treatment (6) RAC + TBA steers (RAC + TBA) was included in years 3 and 4. Overall dry matter intake (DMI) of heifers was increased (P < 0.001) by TBA but not MGA. Compared with H-CONs, H-TBA had greater average daily gain (ADG) (P < 0.001), gain to feed ratio (G/F) (P < 0.001), and carcass weight (P < 0.001), whereas S-TBA had increased ADG (P < 0.001), G/F (P< 0.001), and carcass weight (P < 0.001) compared with S-CON. Compared with H-CON, H-MGA had increased (P < 0.01) ADG, G/F, and carcass weight. The RAC + TBA had increased (P < 0.01) ADG and carcass weight (3.2%) but not G/F or DMI compared with S-TBA. This 4 yr study showed a consistent positive impact of growth-enhancing technologies on the performance of Canadian feedlot cattle.

Effect of tannins from tropical plants on methane production from ruminants: A systematic review

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A negative relationship was observed between the level of tannin inclusion and CH₄ emission.

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The effect of CH₄ mitigation is increasing as the level of tannin inclusion is higher.

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Sub-group analysis revealed differences of tannins supplementation response according to CH₄ emission measurements techniques.

Methane (CH₄) is a greenhouse gas generated during the feed fermentation processes in the rumen. However, numerous studies have been conducted to determine the capacity of plant secondary metabolites to enhance ruminal fermentation and decrease CH₄ production, especially those plants rich in tannins. This review conducted a descriptive analysis and meta-analysis of the use of tannin-rich plants in tropical regions to mitigate CH₄ production from livestock. The aim of this study was to analyse the effect of tannins supplementation in tropical plants on CH₄ production in ruminants using a meta-analytic approach and the effect on microbial population. Sources of heterogeneity were explored using a meta-regression analysis. Final database was integrated by a total of 14 trials. The ‘meta’ package in R statistical software was used to conduct the meta-analyses. The covariates defined a priori in the current meta-regression were inclusion level, species (sheep, beef cattle, dairy cattle, and cross-bred heifers) and plant. Results showed that supplementation with tropical plants with tannin contents have the greatest effects on CH₄ mitigation . A negative relationship was observed between the level of inclusion and CH₄ emission (−0.09), which means that the effect of CH₄ mitigation is increasing as the level of tannin inclusion is higher. Therefore, less CH₄ production will be obtained when supplementing tropical plants in the diet with a high dose of tannins.

Growth Performance, Meat Quality and Antioxidant Status of Sheep Supplemented with Tannins: A Meta-Analysis

The objective of this study was to evaluate the effects of dietary supplementation with tannins (TANs) on productive performance, carcass characteristics, meat quality, oxidative stability, and blood serum antioxidant capacity of sheep through a meta-analysis. Using Scopus, Web of Science, ScienceDirect, and PubMed databases, a systematic search was performed for studies published in scientific journals that investigated the effects of TANs supplementation on the variables of interest. Only studies with weaned or older sheep were included. The data analyzed were extracted from 53 peer-reviewed publications. The sheep included in the present study were between 2 and 6 months old, and between 12 and 31 kg of body weight. The effects of TANs were analyzed using random-effects statistical models to examine the standardized mean difference (SMD) between treatments with TANs and control (no TANs). Heterogeneity was explored by meta-regression and a subgroup analysis was performed for covariates that were significant. Supplementation with TANs did not affect dry matter intake, pH, color (L* and b*), Warner-Bratzler shear force, cooking loss and meat chemical composition (p > 0.05). Supplementation with TANs increased daily weight gain (SMD = 0.274, p < 0.05), total antioxidant capacity (SMD = 1.120, p < 0.001), glutathione peroxidase enzyme activity (SMD = 0.801, p < 0.001) and catalase (SMD = 0.848, p < 0.001), and decreased malondialdehyde (MDA) concentration in blood serum (SMD = -0.535, p < 0.05). Supplementation with TANs decreased feed conversion rate (SMD = -0.246, p < 0.05), and the concentration of MDA (SMD = -2.020, p < 0.001) and metmyoglobin (SMD = -0.482, p < 0.05) in meat. However, meat redness (SMD = 0.365), hot carcass yield (SMD = 0.234), cold carcass yield (SMD = 0.510), backfat thickness (SMD = 0.565) and the Longissimus dorsi muscle area (SMD = 0.413) increased in response to TANs supplementation (p < 0.05). In conclusion, the addition of tannins in sheep diets improves productive performance, antioxidant status in blood serum, oxidative stability of meat and some other characteristics related to meat and carcass quality.

Recent Advances in the Development of Catalytic Methods that Construct Medium-ring Lactams, Partially Saturated Benzazepines and their Derivatives

Recent catalytic methods to construct medium-sized lactams and partially saturated benzazepines and their derivatives are surveyed. The review is divided into the following sections: 1 Introduction 2 Non-Transition Metal Catalyzed Reactions 2.1 Beckmann Rearrangement 2.2 Non-Beckmann Rearrangement Reactions 2.3 Multi-component reactions 3 Transition Metal-Catalyzed Reactions 3.1 Au-catalyzed reactions to access medium-sized N-heterocycles 3.2 Reactions involving a metal η³-complex catalytic intermediate 3.3 Transition metal-catalyzed reactions of strained cycloalkanes 4 Conclusions.

Meat tenderness: advances in biology, biochemistry, molecular mechanisms and new technologies

Meat tenderness is an important quality trait critical to consumer acceptance, and determines satisfaction, repeat purchase and willingness-to-pay premium prices. Recent advances in tenderness research from a variety of perspectives are presented. Our understanding of molecular factors influencing tenderization are discussed in relation to glycolysis, calcium release, protease activation, apoptosis and heat shock proteins, the use of proteomic analysis for monitoring changes, proteomic biomarkers and oxidative/nitrosative stress. Each of these structural, metabolic and molecular determinants of meat tenderness are then discussed in greater detail in relation to animal variation, postmortem influences, and changes during cooking, with a focus on recent advances. Innovations in postmortem technologies and enzymes for meat tenderization are discussed including their potential commercial application. Continued success of the meat industry relies on ongoing advances in our understanding, and in industry innovation. The recent advances in fundamental and applied research on meat tenderness in relation to the various sectors of the supply chain will enable such innovation.

Comparison of beta-ligands used in cattle production: structures, safety, and biological effects

Technologies that increase the efficiency and sustainability of food animal production to provide meat for a growing population are necessary and must be used in a manner consistent with good veterinary practices, approved labeled use, and environmental stewardship. Compounds that bind to beta-adrenergic receptors (β-AR), termed beta-adrenergic receptor ligands (β-ligands), are one such technology and have been in use globally for many years. Though all β-ligands share some similarities in structure and function, the significance of their structural and pharmacological differences is sometimes overlooked. Structural variations in these molecules can affect absorption, distribution, metabolism, and excretion as well as cause substantial differences in biological and metabolic effects. Several β-ligands are available for use specifically in cattle production. Ractopamine and zilpaterol are beta-adrenergic agonists approved to increase weight gain, feed efficiency, and carcass leanness in cattle. They both bind to and activate β1- and β2-AR. Lubabegron is a newly developed selective beta-adrenergic modulator with unique structural and functional features. Lubabegron displays antagonistic behavior at the β1- and β2-AR but agonistic behavior at the β3-AR. Lubabegron is approved for use in cattle to reduce ammonia emissions per unit of live or carcass weight. Additionally, lubabegron can withstand prolonged use as the β3-AR lacks structural features needed for desensitization. Due to these unique features of lubabegron, this new β-ligand provides an additional option in cattle production. The individual properties of each β-ligand should be considered when making risk management decisions, as unique properties result in varying human food safety profiles that can determine appropriate safe β-ligand use.

Modular Entry to Functionalized Tetrahydrobenzo[b]azepines via the Palladium/Norbornene Cooperative Catalysis Enabled by a C7-Modified Norbornene

Tetrahydrobenzo[b]azepines (THBAs) are commonly found in many bioactive compounds; however, the modular preparation of functionalized THBAs remains challenging to date. Here, we report a straightforward method to synthesize THBAs directly from simple aryl iodides via palladium/norbornene (Pd/NBE) cooperative catalysis. Capitalizing on an olefin-tethered electrophilic amine reagent, an ortho amination followed by 7-exo-trig Heck cyclization furnishes the seven-membered heterocycle. To overcome the difficulty with ortho-unsubstituted aryl iodide substrates, we discovered a unique C7-bromo-substituted NBE (N1) to offer the desired reactivity and selectivity. In addition to THBAs, synthesis of other benzo-seven-membered ring compounds can also be promoted by N1. Combined experimental and computational studies show that the C7-bromo group in N1 plays an important and versatile role in this catalysis, including promoting β-carbon elimination, suppressing benzocyclobutene formation, and stabilizing reaction intermediates. The mechanistic insights gained could guide future catalyst design. The synthetic utility has been demonstrated in a streamlined synthesis of tolvaptan and forming diverse pharmaceutically relevant THBA derivatives. Finally, a complementary and general catalytic condition to access C6-substituted THBAs from ortho-substituted aryl iodides has also been developed.

Effects of Dietary Tannins’ Supplementation on Growth Performance, Rumen Fermentation, and Enteric Methane Emissions in Beef Cattle: A Meta-Analysis

The environmental sustainability of beef production is a significant concern within the food production system. Tannins (TANs) can be used to minimize the environmental impact of ruminant production because they can improve ruminal fermentation and ruminants’ lifetime performances and mitigate methane (CH4) emissions. The objective of this study was to evaluate the effects of dietary supplementation with TANs as sustainable natural alternative to reduce the environmental impact on growth performance, rumen fermentation, enteric CH4 emissions, and nitrogen (N) use efficiency of beef cattle through a meta-analysis. A comprehensive search of studies published in scientific journals that investigated the effects of TANs’ supplementation on the variables of interest was performed using the Scopus, Web of Science, and PubMed databases. The data analyzed were extracted from 32 peer-reviewed publications. The effects of TANs were assessed using random-effects statistical models to examine the standardized mean difference (SMD) between TANs’ treatments and control (non-TANs). The heterogeneity was explored by meta-regression and subgroup analysis was performed for the covariates that were significant. TANs’ supplementation did not affect weight gain, feed consumption, feed efficiency, or N use efficiency (p > 0.05). However, it reduced the concentration of ammonia nitrogen in rumen (SMD = −0.508, p < 0.001), CH4 emissions per day (SMD = −0.474, p < 0.01) and per unit dry matter intake (SMD = −0.408, p < 0.01), urinary N excretion (SMD = −0.338, p < 0.05), and dry matter digestibility (SMD = −0.589, p < 0.001). Ruminal propionate (SMD = 0.250) and butyrate (SMD = 0.198) concentrations and fecal N excretion (SMD = 0.860) improved in response to TANs’ supplementation (p < 0.05). In conclusion, it is possible to use TANs as a CH4 mitigation strategy without affecting cattle growth rate. In addition, the shift from urinary to fecal N may be beneficial for environment preservation, as urinary N induces more harmful emissions than fecal N. Therefore, the addition of tannins in the diet of beef cattle could be used as a sustainable natural alternative to reduce the environmental impact of beef production.

Effect of ractopamine hydrochloride on environmental gas emissions, growth performance, and carcass characteristics in feedlot steers

With a growing global population and increased environmental concerns around animal agriculture, it is essential to humanely maximize animal performance and reduce environmental emissions. This study aims to determine the efficacy of feeding ractopamine hydrochloride (RAC), an orally active, β 1-adrenergic agonist (β1AA), to feedlot steers in the last 42 d of finishing to reduce ammonia (NH3) emissions and improve animal performance. A randomized complete block design was used to allocate 112 Angus and crossbred Angus steers (initial body weight [BW] = 566.0 ± 10.4 kg) to 8 cattle pen enclosures. Pens (n = 4 per treatment, 14 steers per pen, and 56 steers per treatment) were randomly assigned to one of two treatments: 1) CON; finishing ration containing no RAC, 2) RAC; finishing ration containing 27.3 g/907 kg dry matter (DM) basis RAC. Steers were weighed on day -1 and 0 before treatment and day 14, 28, and 42 during treatment. Treatment rations were mixed and delivered daily by masked personnel. Measured emissions included NH3, nitrous oxide (N2O), methane (CH4), hydrogen sulfide (H2S), and carbon dioxide (CO2). The primary response variables assessed were emissions standardized by live weight (LW) and hot carcass weight (HCW). Steers were harvested on day 43 and carcass data were collected on day 43 and 44. Steers fed RAC reduced NH3 emissions by 17.21% from day 0 to 28 (P = 0.032) and tended to reduce NH3 from day 0 to 42 by 11.07% (P = 0.070) vs. CON. When standardized for LW, NH3 was reduced by 23.88% from day 0 to 14 (P = 0.018), 17.80% from day 0 to 28 (P = 0.006), and 12.50% for day 0 to 42 (P = 0.027) in steers fed RAC vs. CON. Steers fed RAC had 14.05% (P = 0.013) lower cumulative NH3 emissions when standardized by HCW vs. CON. Feeding RAC to Steers reduced H2S by 29.49% from day 0 to 14 (P = 0.009) and tended to reduce H2S over day 0 to 28 by 11.14% (P = 0.086) vs. CON. When H2S emissions were standardized for LW, RAC fed steers had a 28.81% reduction from day 0 to 14 (P = 0.008) vs. CON. From day 0 to 42 the RAC fed steers tended to have a 0.24 kg/d greater average daily gain (ADG) (P = 0.066) and tended to eat 4.27% less (P = 0.069) on a DM basis vs. CON. The RAC fed steers had a 19.95% greater gain to feed ratio (G:F) compared to CON (P = 0.012). Steers fed RAC had an average of 12.52 kg greater HCW (P = 0.006) and an increase of 1.93 percentage units in dressing percent (DP) (P = 0.004) vs. CON. Ractopamine is an effective medicated feed additive for reducing NH3 and improving end product performance through HCW yields.

Effects of voluntary removal of ractopamine hydrochloride (Optaflexx) on live performance and carcass characteristics of beef steers

There is a lack of consistency across the globe in how countries establish tissue ractopamine residue limits and which residue limits are applied to various tissues, particularly for edible noncarcass tissues. Therefore, some U.S. beef slaughter organizations have recommended a 48-h voluntary removal of ractopamine before slaughter to meet residue requirements of specific export countries and maintain international trade. Our objective was to assess the impact of voluntary removal of ractopamine hydrochloride (Optaflexx; Elanco, Greenfield, IN) up to 8 d before slaughter on growth performance and carcass characteristics. Crossbred beef steers (60 pens of 10 animals/pen) with an initial shrunk body weight (BW) of 611.8 ± 10 kg SEM were fed one of six treatments over 42 d. Treatments included a control that did not receive ractopamine, on-label use of ractopamine (0-d withdrawal), and 2, 4, 6, or 8 d of voluntary removal of ractopamine from feed before slaughter. The start of ractopamine feeding (30.1 mg/kg of diet dry matter for 32 d) was staggered, so that blocks could be slaughtered on the same day. Dry matter intake was decreased by 0.5 kg/d when ractopamine was fed with a 0-d withdrawal (P = 0.04) compared with the control, but was not altered (P = 0.56) as the duration of ractopamine removal increased from 0 to 8 d. Final BW, total BW gain, and average daily BW gain were increased by feeding ractopamine with a 0-d withdrawal (P = 0.09) compared with the control, but these variables decreased in a linear manner (P = 0.10) as the duration of removal increased from 0 to 8 d. Gain efficiency was improved by 15% (P < 0.01) by feeding ractopamine with a 0-d withdrawal compared with the control, and gain efficiency decreased linearly (P = 0.06) as the duration of ractopamine removal increased. Approximately 2/3 of the increase in gain efficiency remained after 8 d of removal. Hot carcass weight was increased by 6 kg (P = 0.02) by feeding ractopamine with a 0-d withdrawal compared to the control. Measured carcass characteristics were not altered by ractopamine feeding or by removal before slaughter (P ≥ 0.24). The consequences of voluntary removal of ractopamine up to 8 d before slaughter were a linear decrease in live BW gain (0.64 kg/d), poorer gain efficiency, and numerically lighter carcass weight.

Influence of ractopamine hydrochloride supplementation on pancreatic digestive enzyme activity in finishing steers

Sixty-nine finishing steers were randomly assigned to one of two treatment groups: supplementation to provide 0 or 267 mg·d−1 of ractopamine hydrochloride (RAC) for 42 d. Twelve steers were slaughtered for tissue and blood collection. Final body weight (BW) tended to be greater with RAC supplementation. Ractopamine hydrochloride supplementation decreased liver mass as a percentage of BW. Pancreatic protein concentration, digestive enzyme activities, serum glucose, and insulin concentrations were not influenced by RAC supplementation. Ractopamine hydrochloride supplementation decreased the pancreatic:α-amylase:trypsin and serum urea nitrogen concentrations. These data suggest that RAC may influence pancreatic exocrine function in cattle.

Rumination time as an early predictor of metritis and subclinical ketosis in dairy cows at the beginning of lactation: Systematic review-meta-analysis

Daily rumination time (RT; min/d) is recognized as an important tool for assessing the health of dairy cows, which may depend on the disease, lactation stage and individual cows. Using a systematic review-meta-analysis, this study evaluated whether the variation in RT is effective for early detection of metritis and subclinical ketosis (SCK) in dairy cows in the pre and post-partum periods (from three weeks before to three weeks after calving). The research was carried out in four electronic databases - Scopus, Science Direct, Pubmed and Web of Science. The main inclusion criteria were original research; evaluation of RT in dairy cows; and use of RT for early identification of metritis and/or SCK in post-partum dairy cows. A random effect meta-analysis (MA) was conducted for each disease (metritis and SCK) separately, with the RT means of healthy and sick groups, measured in the pre and post-partum. The effect size used was the mean difference (MD).Twenty-two trials from six studies were included in the MA, involving 1494 dairy cows. For metritis, four trials from three studies in the pre-partum period were considered as well as five trials from four studies in the post-partum. For SCK, six trials from four studies pre-partum and seven trials from five studies in the post-partum period were taken into consideration. The heterogeneity between studies for metritis was null (I² = 0%) and low (I² = 5.7 %) in the pre-partum and in the post-partum, respectively. The MD of RT between healthy cows and those with metritis was different in the pre (MD =0.411 min/d; P < 0.001) and in the post-partum (MD =0.279 min/d; P < 0.001). In SCK, heterogeneity was high in the pre (I² = 69 %) and in the post-partum (I² = 58.1 %), and the MD of RT was similar between healthy and sick cows (P> 0.05). In a meta-regression, RT from primiparous cows showed a lower predicted value for MD (0.48 min. d; P < 0.05) compared to multiparous cows, and the increment in each unit of milk production decreased the predicted MD value by 0.08 min. d (P < 0.001). Our MA demonstrates that RT is a good predictor for early detection of metritis in pre and post-partum; however, it is not an adequate predictor for SCK. Further investigations using more frequent blood sampling and the same threshold values for BHB are required to assess the adequacy of rumination time to predict SCK.

Zinc supplementation improves growth performance in small ruminants: a systematic review and meta-regression analysis

Appropriate supplementation of trace minerals is fundamental to enhance the metabolic status of growing animals and promote an adequate expression of genetic potential. Zinc (Zn) is an essential mineral fundamental in many biological processes that are related to growth, energy balance and immunity. The aim of the present study was to analyse the effect of Zn supplementation on growth parameters in small ruminants by using a meta-analytic approach. Sources of heterogeneity were explored using a meta-regression analysis. The final database was integrated from a total of 53 trials. Only indexed articles that provided an effect size measure, variability measure, sample size and randomisation of the procedure were considered. The dependent variables considered for the study were average daily gain (ADG), dry-matter intake (DMI), feed conversion ratio (FCR), final bodyweight, and glucose blood concentration. The exploratory variables included species (sheep and goat), breed, production level, Zn source and dosage. The ‘meta’ package in R statistical software was used to conduct the meta-analyses. For response variables that showed substantial heterogeneity (I2 &gt; 50%), mixed-effect models (meta-regression analysis) were constructed to explore the sources of heterogeneity using the ‘Metafor’ package. DMI was higher in animals supplemented with Zn (&gt;21.08 g/day, P = 0.0001). Breed, species, production level, and dosage reduced heterogeneity of DMI response from I2 = 84.8 to I2 = 48.1%. Zn-supplemented animals showed higher ADG (17.39 g/day, P = 0.001), which was affected by species, breed dosage and Zn-source. Zn supplementation improved feed efficiency, with lower values of FCR (–1.56 g/g, P &lt; 0.0001). There was a positive relationship between the dosage and effect size in all outcome variables (P &lt; 0.05). Zn-proteinate showed the best response in both species to ADG, FCR and final body weight. Our findings of the systematic review concluded that dietary Zn supplementation improves growth performance in small ruminants and their level of response is influenced mainly by species, production level, and Zn-source and dosage.

Effect of selenium supplementation on productive performance and antioxidant status of broilers under heat stress: a meta-analysis and a meta-regression

Heat stress and a high metabolic rate of broilers increase the production of reactive oxygen species, which must be removed by antioxidants to prevent oxidative stress. Selenium (Se) is a potent antioxidant as it is a structural part of glutathione peroxidase (GPx). Dietary supplementation of Se can help reduce the oxidative stress caused by heat-stress conditions. The aim was to evaluate the effect of Se supplementation on the performance and antioxidant status of broilers under heat stress, by using a meta-analysis approach, and to quantify the contribution to heterogeneity of the explanatory variables through a meta-regression procedure. A database of 74 trials was created from 56 published studies that met the following inclusion criteria: papers that reported a measure of effect size, sample size, measure of variability and random procedure. The response variables were GPx and malondialdehyde concentrations, DM intake, average daily gain, and feed conversion rate. Broiler line, Se source, and dosage, heat-stress level, days of experimentation, sample source (blood, liver or meat) and basal Se concentration were considered to be explanatory variables. All statistical analyses were performed in R software, by using the ‘meta’ and ‘Metafor’ packages for meta-analysis and meta-regression respectively. High concentrations of GPx were found in Se-supplemented broilers (&gt;1.76; P = 0.001), in comparison to control groups. However, when the random model was applied to GPx studies, it showed high heterogeneity (I2 = 95.4%), which was reduced (I2 = 61.5) when heat-stress temperature, Se source and its dosage and tissue sample were included as covariates in the meta-regression analysis. The highest standard mean difference of GPx was founded in studies that reported supplementation with inorganic Se sources (2.92), in comparison to supplementation with organic and nano-Se sources (1.66 and 1.44 respectively). The standard mean differences of malondialdehyde and feed conversion rate were significantly lower (&lt;0.66 and &lt;0.11 respectively) in supplemented broilers. Heterogeneity of all variables decreased when the explanatory variables were included in the mixed-regression model. Our findings confirmed that Se supplementation improves the broiler’s antioxidant status and productive performance. However, the response level was affected by dosage and source of Se and the level of heat stress.

Cattle and carcass performance, and life cycle assessment of production systems utilizing additive combinations of growth promotant technologies

The objective of this study was to determine the impact of beef production systems utilizing additive combinations of growth promotant technologies on animal and carcass performance and environmental outcomes. Crossbred steer calves (n =120) were stratified by birth date, birth weight, and dam age and assigned randomly to one of four treatments: 1) no technology (NT; control), 2) antibiotic treated (ANT; NT plus therapeutic antibiotics and monensin and tylosin), 3) implant treated (IMP; ANT plus a series of 3 implants, and 4) beta-agonist treated (BA; IMP plus ractopamine-HCl for the last 30 d prior to harvest). Weaned steers were fed in confinement (dry lot) and finished in an individual feeding system to collect performance data. At harvest, standard carcass measures were collected and the United States Department of Agriculture (USDA) Yield Grade and Quality Grade were determined. Information from the cow-calf, growing, and finishing phases were used to simulate production systems using the USDA Integrated Farm System Model, which included a partial life cycle assessment of cattle production for greenhouse gas (GHG) emissions, fossil energy use, water use, and reactive N loss. Body weight in suckling, growing, and finishing phases as well as hot carcass weight was greater (P < 0.05) for steers that received implants (IMP and BA) than non-implanted steers (NT and ANT). The average daily gain was greater (P < 0.05) for steers that received implants (IMP and BA) than non-implanted steers during the suckling and finishing phases, but no difference (P = 0.232) was detected during the growing phase. Dry matter intake and gain:feed were greater (P < 0.05) for steers that received implants than non-implanted steers during the finishing phase. Steers that received implants responded (P < 0.05) with a larger loin muscle area, less kidney pelvic and heart fat, advanced carcass maturity, reduced marbling scores, and a greater percentage of carcasses in the lower third of the USDA Choice grade. This was offset by a lower percentage of USDA Prime grading carcasses compared with steers receiving no implants. Treatments did not influence (P > 0.05) USDA Yield grade. The life cycle assessment revealed that IMP and BA treatments reduced GHG emissions, energy use, water use, and reactive nitrogen loss compared to NT and ANT. These data indicate that growth promoting technologies increase carcass yield while concomitantly reducing carcass quality and environmental impacts.

A Meta-Analysis of the Effectiveness of High, Medium, and Low Voltage Electrical Stimulation on the Meat Quality of Small Ruminants

The current study is a meta-analysis of the effects of electrical stimulation (ES, n = 28 papers) with different voltages combined with different ageing periods (0–3, 4–7, and 8–14 days) on the meat quality of small ruminants. A comprehensive search for published studies on meat quality of small ruminants investigating the application of low, medium, and high voltage electrical stimulation, was performed using Google Scholar, ScienceDirect, PubMed, and Scopus databases. Forest plots, funnel plots, and other statistical tools and tests were used in the study to analyze the results. Electrical stimulation significantly reduced ultimate pH (p < 0.001), Warner–Bratzler shear force (WBSF) (p < 0.001), cooking loss (p < 0.05), and purge loss (p < 0.001). In addition, sarcomere length (p < 0.01), myofibrillar-fragmentation index (MFI) (p < 0.001), and color (L*, a*, b*) (p < 0.001) showed higher values in meat subjected to ES as compared with the control group. In conclusion, the meta-analysis revealed statistical proof of beneficial effects of ES on meat quality of small ruminants in terms of ultimate pH, tenderness, enhanced proteolysis, and higher colorimetric values.

The influence of dietary energy and zinc source and concentration on performance, trace mineral status, and gene expression of beef steers

The objective of this study was to determine the effects of increased supplemental Zn from differing sources on growth performance of steers fed diets differing in net energy. Angus steers (n = 72, 324 ± 2.1 kg) with Genemax gain scores of 3, 4, or 5 were blocked by BW and stratified by Genemax gain score into 12 pens of 6 steers each for 158 d. Pens were randomly assigned to 1 of 3 Zn treatments (ZNTRT): 1) control (no supplemental Zn, analyzed 33 mg Zn/kg DM; CON); 2) inorganic Zn (CON + 120 mg supplemental Zn/kg DM as ZnSO₄ for entire trial; INZN); or 3) 120 mg supplemental Zn/kg DM as Zn-amino acid complex (Availa-Zn; Zinpro, Eden Prairie, MN) for first 60 d, then a blend of ZnSO₄ and Zn-AA complex (CON + 60 mg supplemental Zn/kg DM as ZnSO₄ + 60 mg supplemental Zn/kg DM as Zn-amino acid complex) for the remainder of the trial (ZNBLD). Two dietary energy strategies (ENERGY) were formulated to reach ADG rates of 1) 1.6 kg/d (LE) or 2) 2.0 kg/d (HE) utilizing a 3 × 2 factorial arrangement (12 steers/treatment). All steers were fed LE for a 60 d growing period, then pens were randomly assigned to ENERGY treatments fed the remaining 91 d. Day 60 BW tended to be greater (P = 0.07) in steers receiving supplemental Zn vs. CON. Liver Cu was decreased in Zn supplemented steers vs. CON (P = 0.02). Liver Zn concentrations on d 56 did not differ for Zn vs. CON (P = 0.22) nor were there differences due to Zn source (P = 0.98). There were or tended to be ZNTRT × ENERGY effects for d 67-90 ADG and G:F (P ≤ 0.01), and d 122 BW and d 90-122 G:F (P ≤ 0.10) driven by improved performance for ZNBLD-HE over ZNBLD-LE, while ENERGY within CON and INZN did not differ. Day 90-122 ADG, overall ADG and overall G:F was greater (P ≤ 0.02) and d 67-90 G:F tended to be greater (P = 0.10) for HE vs. LE. No ZNTRT × ENERGY or ZNTRT effects were detected for HCW, REA, BF, KPH, MS, or YG (P ≥ 0.37) while HE increased HCW, BF, MS, and YG compared with LE (P ≤ 0.05). In the liver, ZNTRT affected d 97 MT1A expression (P = 0.03) where INZN was greater than ZNBLD or CON (P ≤ 0.02), while ZIP14 was unaffected due to ZNTRT, ENERGY, or the interaction (P ≥ 0.39). Supplying supplemental Zn as ZNBLD during the transition period appeared to improve performance measures, but no final performance advantages were noted due to increased supplemental Zn, regardless of source. Additionally, differences in liver MT1A expression may indicate differing post-absorptive metabolism between Zn sources.

An assessment of the impacts of litter treatments on the litter quality and broiler performance: A systematic review and meta-analysis

Objective

The choice of the most suitable litter treatment should be based on scientific evidence. This systematic review assessed the effectiveness of litter treatments on ammonia concentration, pH, moisture and pathogenic microbiota of the litter and their effects on body weight, feed intake, feed conversion and mortality of broilers.

Methods

The systematic literature search was conducted using PubMed (Medline), Google Scholar, ScienceDirect and Scielo databases to retrieve articles published from January 1998 to august 2019. Means, standard deviations and sample sizes were extracted from each study. The response variables were analyzed using the mean difference (MD) or standardized mean difference (SMD), (litter treatment minus control group). All variables were analyzed using random effects meta-analyses.

Results

Subgroup meta-analysis revealed that acidifiers reduce pH (P<0.001), moisture (P = 0.002) ammonia (P = 0.011) and pathogenic microbiota (P <0.001) of the litter and improves the weight gain (P = 0.019) and decreases the mortality rate of broilers (P<0.001) when compared with controls. Gypsum had a positive effect on ammonia reduction (P = 0.012) and improved feed conversion (P = 0.023). Alkalizing agents raise the pH (P = 0.035), worsen feed conversion (P<0.001), increase the mortality rate (P <0.001), decrease the moisture content (P<0.001) and reduce the pathogenic microbiota of the litter (P<0.001) once compared to controls. Superphosphate and adsorbents reduce, respectively, pH (P<0.001) and moisture (P = 0.007) of the litter compared to control groups.

Conclusion

None of the litter treatments influenced the feed intake of broilers. Meta-analyses of the selected studies showed positive and significant effects of the litter treatments on broiler performance and litter quality when compared with controls. Alkalizing was associated with worse feed conversion and high mortality of broilers.

A Meta-Analysis of the Effects of Slow-Release Urea Supplementation on the Performance of Beef Cattle

Slow-release urea (SRU) is a coated non-protein nitrogen (NPN) source for ruminant nutrition. This study applied a meta-analytic technique to quantify the effect of a commercial SRU (Optigen^®, Alltech Inc., Nicholasville, KY, USA) on the performance of beef cattle. Data were extracted from 17 experiments and analysed using the random-effects model to estimate the effect size of SRU on dry matter intake (DMI), crude protein intake (CPI), live weight gain (LWG) and feed efficiency (FE) of growing and finishing beef cattle. There was no effect of feeding SRU on the overall DMI and CPI of beef cattle. Dietary inclusion of SRU improved the overall LWG (+92 g/d/head) and FE (+12 g LWG/kg DMI/head) of beef cattle. Notably, SRU supplementation in growing cattle exhibited a better improvement on LWG (130 vs. 60 g/d/head) and FE (18 vs. 8 g LWG/kg DMI/head) compared with finishing cattle. Moreover, SRU showed consistent improvements on the LWG and FE of beef cattle under several study factors. Simulation analysis indicated that positive effects of SRU on LWG and FE improved profitability through reduction in feed cost and reduced the emission intensity of beef production. These results indicate that SRU is a sustainable NPN solution in beef cattle production.

Effects of various ractopamine hydrochloride withdrawal periods on performance, health, and carcass characteristics in yearling steers

Ractopamine hydrochloride (RAC) is a β-adrenergic agonist approved for feeding during the last 28 to 42 d prior to cattle slaughter to improve feedlot performance and carcass characteristics. Three thousand crossbred yearling steers (527 ± 2.4 kg; AVG ± SD) were used in two periods to evaluate the effects of various RAC withdrawal times on feedlot performance, health, and carcass characteristics. In Period 1, 6 blocks of 30 pens totaling 1,500 steers were utilized, which was repeated for Period 2. In a randomized complete block design, cattle were assigned to 1 of 5 treatments consisting of 1) No RAC fed (CON), 2) 12-h RAC withdrawal (12-hRAC), 3) 2-d RAC withdrawal (2-dRAC), 4) 4-d RAC withdrawal (4-dRAC), and 5) 7-d RAC withdrawal (7-dRAC). Cattle were fed for a total of 62 d, and applicable treatments were supplemented with 30.0 ppm (dry matter basis) of RAC (average dose = 322 mg per steer per day) for 33 d at the end of the feeding period, corresponding to their respective withdrawal times. Initial body weight (BW) displayed a quadratic curve, with 2-dRAC and 4-dRAC withdrawal periods having the greatest BW. Accordingly, dry matter intake (DMI) responded quadratically (P = 0.034), with 2-dRAC and 4-dRAC treatments demonstrating the greatest DMI. No significant treatment differences (P ≥ 0.641) were observed in final live BW, average daily gain (ADG), or feed efficiency. Alternatively, when using a common dressing percentage to calculate live BW, cattle on RAC treatments exhibited 7.6 kg additional live BW (P < 0.001) compared to CON cattle. Furthermore, carcass-adjusted ADG and feed efficiency did not differ (P > 0.10) between RAC treatments but were improved compared to the CON treatment (P ≤ 0.002). Hot carcass weight (HCW) was on average 4.9 kg greater (P < 0.001) for RAC treatments vs. CON, and no differences were detected (P > 0.10) among RAC treatments. Within RAC treatments, carcass cutability responded quadratically (P ≤ 0.005) to withdrawal period, with the 2-dRAC and 4-dRAC treatments containing more Yield Grade 4 and 5 and fewer Yield Grade 1 and 2 carcasses than the other RAC treatments. On the basis of the results of this experiment, feeding RAC improves dressing percentage, HCW, and carcass-adjusted BW, ADG, and feed efficiency. Furthermore, extending the RAC withdrawal period to 7 d does not have a significant impact on cattle performance or health and has minimal effects on carcass characteristics.

The effect of litter materials on broiler performance: a systematic review and meta-analysis

1. Divergence in outcomes from studies on the effects of litter materials on body weight, feed intake, feed conversion and mortality in broilers has led to a need for a meta-analysis to quantify their effects.2. A systematic search of published quantitative research relating to wood shavings and alternative bedding litters was conducted using databases.3. Means, standard deviations and sample sizes were extracted from each study. The response variables were analysed using the standardised mean difference (SMD, control treatment minus alternative litters).4. The literature demonstrated that alternative materials have no impact on feed intake in broilers, compared to wood shavings (SMD = 0.064, 95% CI = -0.101-0.229, P = 0.44).5. There was a positive overall effect of wood shavings on body weight (SMD = 0.253, 95% CI = 0.073-0.433, P = 0.006), feed conversion (SMD = -0.169, 95% CI = -0.327 - -0.012, P = 0.03) and mortality (SMD = -1.069, 95% CI = -1.983 - -0.155, P = 0.02) of broilers, compared to other litter types.6. Subgroup meta-analysis revealed that straw, when used as an alternative litter material to wood shavings, may be responsible for lower body weight (SMD = 0.654, 95% CI = 0.162-1.146, P = 0.009), worse feed conversion (SMD = -0.487, 95% CI = -0.828 - -0.145, P = 0.005) and higher mortality rates of broilers (SMD = -3.25, 95% CI = -5.681 - -0.819, P = 0.009). Rice husks impaired body weight compared to wood shavings (SMD = 0.535, 95% CI = 0.065-1.004, P = 0.02).7. It was concluded that different litter types do not affect the broilers' feed intake. Conversely, broilers kept on straw showed lower body weights, worse feed conversion and higher mortality rates, in comparison to wood shavings. Rice husks decreased body weight compared to wood shavings.

Effects of ractopamine hydrochloride supplementation on feeding behavior, growth performance, and carcass characteristics of finishing steers. Transl Anim Sci 2019;3:1143-1152. [PMID: 32704878 PMCID: PMC7200486 DOI: 10.1093/tas/txz114]

Ractopamine hydrochloride (RAC) is a β-adrenergic agonist that functions as a repartitioning agent to improve muscling in feedlot cattle. Many studies have investigated the effects of RAC on growth performance and carcass characteristics; however, there is minimal information about the influence of RAC on feeding behavior. Sixty-nine steers (body weight [BW] = 364 ± 3.9 kg) predominately of Angus and Simmental breeding were subjected to a 126-d (n = 46) or 154-d (n = 23) feeding period and randomly assigned to one of two treatment groups: supplementation to provide 0 (CON; n = 34) or 267 ± 4.9 mg/d of RAC (n = 35). Ractopamine was provided as Optaflexx 45 at 0.024% of the diet (dry matter [DM] basis; Elanco Animal Health, Greenfield, IN). Dietary treatments were fed the final 42 d in the feed yard (treatment period). Feeding behavior and growth performance were measured using radio frequency identification tags and the Insentec feeding system. Following the final day of treatment, steers were slaughtered and carcass measurements were recorded. Data were analyzed using MIXED models in SAS. There were no differences in BW, average daily gain (ADG), DM intake (DMI), gain:feed ratio (G:F), or feeding behavior during the pretreatment period (P > 0.44). Ractopamine supplementation increased G:F during the treatment period (P = 0.02) and during the total period (P = 0.03) and tended to increase ADG during the treatment and total period (P ≤ 0.08). DMI was not affected during the treatment or total period (P > 0.67). Eating time per visit, per meal, and per day were decreased (P < 0.02) in steers supplemented with RAC during the treatment period. DMI per minute was increased (P = 0.02) in steers supplemented with RAC. Hot carcass weight, dressing percentage, and 12th rib fat were not influenced by RAC supplementation. Ractopamine supplementation decreased marbling (P = 0.008) and kidney, pelvic, and heart percentage (P = 0.04) and increased longissimus muscle area (P = 0.01). These data demonstrate that RAC supplementation for 42 d improves feed efficiency, increases the rate of DMI without altering DMI, and increases muscling in finishing cattle.

Recent advances to improve nitrogen efficiency of grain-finishing cattle in North American and Australian feedlots

Formulating diets conservatively for minimum crude-protein (CP) requirements and overfeeding nitrogen (N) is commonplace in grain finishing rations in USA, Canada and Australia. Overfeeding N is considered to be a low-cost and low-risk (to cattle production and health) strategy and is becoming more commonplace in the US with the use of high-N ethanol by-products in finishing diets. However, loss of N from feedlot manure in the form of volatilised ammonia and nitrous oxide, and nitrate contamination of water are of significant environmental concern. Thus, there is a need to improve N-use efficiency of beef cattle production and reduce losses of N to the environment. The most effective approach is to lower N intake of animals through precision feeding, and the application of the metabolisable protein system, including its recent updates to estimation of N supply and recycling. Precision feeding of protein needs to account for variations in the production system, e.g. grain type, liveweight, maturity, use of hormonal growth promotants and β agonists. Opportunities to reduce total N fed to finishing cattle include oscillating supply of dietary CP and reducing supply of CP to better meet cattle requirements (phase feeding).

Dehorning and welfare indicators in beef cattle: a meta-analysis

Dehorning is a common practice in cattle farming. Researchers suggest that pain during dehorning can be mitigated, although there is no conclusive evidence about the best technique and the best manner of pain relief. A systematic review-meta-analysis was performed to clarify the effect of dehorning on welfare indicators (cortisol concentration or average daily gain or vocalisation) in beef cattle up to 12 months of age. Five electronic databases were systematically searched, as well as conference proceedings and experts were contacted electronically. Pre-defined protocols were applied during all steps of the systematic review process. A random effect meta-analysis was conducted for each indicator separately with the mean of the control and treated groups. Four publications reporting seven studies and 69 trials were included in the MA involving 287 cattle. Heterogeneity between studies was observed for cortisol (I2 = 50.5%), average daily gain (I2 = 70.5%), and vocalisation (I2 = 91.9%). When comparing the non-dehorned group with amputation dehorning, the cortisol concentration was lower 30 min (P &lt; 0.0001) and 120 min (P = 0.023) after procedure (0.767 nmol/L and 0.680 nmol/L, respectively). Local anaesthesia did not show a reduction in cortisol concentration at 30 min after dehorning by amputation. Non-dehorned animals had a tendency to decrease the number of vocalisation (P = 0.081; MD = 0.929) compared with the group dehorned by amputation. These results suggest that dehorning is a painful experience and that local anaesthesia did not alleviate short-term pain following dehorning. Further investigation into pain relief is required to improve confident decision making under practical conditions.

Association of body weight gain with muscle, fat, and liver expression levels of growth hormone receptor, insulin-like growth factor I, and beta-adrenergic receptor mRNAs in steers

The physiological basis of feed efficiency is unclear. Administration of GH or beta-adrenergic agonists improves feed efficiency in various animals. The objective of this study was to test the hypothesis that more efficient cattle have greater expression of GH receptor (GHR) or beta-adrenergic receptor (ADRB) mRNA in skeletal muscle, fat, and liver, the major target tissues of GH and beta-adrenergic agonists. Fifty Angus steers were fed a finishing diet for 75 d to determine residual feed intake (RFI). Carcass measures, skeletal muscle, subcutaneous fat, and liver samples were collected from the top 10 high-RFI steers and top 10 low-RFI steers at slaughter. Abundances of GHR, insulin-like growth factor I (IGF1), IGF1 receptor (IGF1R), beta-1 adrenergic receptor (ADRB1), ADRB2, and ADRB3 mRNAs were quantified by real-time reverse transcription-PCR. Low-RFI steers consumed 11% less dry matter intake than high-RFI steers (P = 0.004). Low- and high-RFI steers, however, did not differ in ADG or other growth or carcass measures. Low-RFI steers had a tendency to have smaller birth weights than high-RFI steers (P = 0.089). The expression levels of GHR, IGF1, IGF1R, ADRB1, ADRB2, and ADRB3 mRNAs in muscle, fat, and liver were neither different (P > 0.1) between high- and low-RFI steers nor correlated (P > 0.1) with RFI. These results do not support our original hypothesis. However, the expression levels of GHR, IGF1, and IGF1R mRNAs in muscle and fat were positively correlated with ADG (r = 0.52 to 0.65, P = 0.002 to 0.02), whereas the expression levels of GHR mRNA (r = -0.50, P = 0.03) and IGF1 mRNA (r = -0.47, P = 0.04) in the liver were negatively correlated with ADG. These results suggest that the GHR, IGF1, and IGF1R mRNA expression levels in the muscle and fat have a positive effect, whereas the GHR and IGF1 mRNA expression levels in the liver have a negative effect on postweaning body weight gain in cattle.