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Controversy has existed as to whether monensin will provide equal or differential benefits in a higher-energy, lower-roughage close-up diet versus a higher-roughage, lower-energy diet. Our objective was to determine the rumen effects of a controlled-energy, high-fiber diet balanced to meet but not greatly exceed energy requirements during the dry period or a traditional 2-group approach of higher-energy close-up diet. The effects of added monensin in each diet type were determined. Multiparous Holstein cows (n = 17) were fitted surgically with ruminal cannulas. During the first 4 wk of the dry period, all cows were fed a controlled-energy, high-fiber diet (CE) as a total mixed ration for ad libitum intake. During the last 3 wk before calving, half of the cows were switched to a higher-energy, close-up diet until calving (CU), whereas the other half continued to receive the CE diet. Within each dietary group, half of the cows received monensin (MON) supplementation in the diet (24.2 g/t of total dry matter) and half did not (CON). After calving, all cows received the same lactation diet containing monensin (15.4 g/t of dietary dry matter). At 14 d prepartum, dry matter intake was not different across treatments. The weight of rumen contents was greater for cows fed CE. Rumen liquid dilution rate, solids passage rate, pH, total volatile fatty acid (VFA) concentrations, molar proportions of acetate and propionate, and papillae length did not differ among diets. Butyrate percentage tended to be greater for cows fed CE. Postpartum, dry matter intake, mass of rumen contents, solids passage rate, pH, total VFA concentration, molar percentages of propionate and butyrate, and papillae length did not differ among treatments. Liquid dilution rate (16.6, 10.7, 16.0, and 18.2%/h for CE + CON, CE + MON, CU + CON, and CU + MON, respectively) was affected by a diet × monensin interaction. Cows on the CE + CON diet had a greater ruminal proportion of acetate than did cows fed CU + CON, whereas cows fed monensin on either diet were intermediate (diet × monensin interaction). Addition of MON to the CU diet decreased the proportion of propionate (diet × monensin interaction). Cows fed CE had greater mass of rumen contents before parturtition but the high inclusion of wheat straw in the CE diet did not negatively affect rumen papillae length. Monensin inclusion differentially affected liquid passage rate and VFA concentrations.

The objectives were to evaluate the effects of monensin and virginiamycin, alone or combined, on supplemented Nellore cattle grazing tropical grass during the rainy season. Two experiments were conducted simultaneously to evaluate intake, digestibility, CH4 emissions, blood parameters, performance, and carcass characteristics (Exp. 1), and ruminal fermentation and relative abundance of ruminal microorganisms (Exp. 2). Animals (n = 92 Exp. 1 and n = 12 Exp. 2) were distributed in a completely randomized design and allocated in twelve paddocks composed of Urochloa brizantha (A. Rich.) Stapf. cv. Xaraés. A protein-energetic supplementation of 3 g/kg of BW per day was provided to all animals. Supplements were: without additives (WA), monensin alone at 80 mg/kg of product (MN), virginiamycin alone at 150 mg/kg of product (VM), and monensin (80 mg/kg of product) combined with virginiamycin (150 mg/kg of product; MNVM). Treatments did not affect intakes of total dry matter (DM), supplement DM, and nutrients. However, the intakes of forage DM and crude protein decreased in cattle fed MNVM compared with animals fed WA, MN, and VM. Total volatile fatty acids increased in animals fed VM. Ruminal NH3-N decreased, and pH increased in animals fed MN, VM, and MNVM. Relative abundance of total F. succinogenes and S. ruminantium decreased and R. flavefaciens increased in animals fed MN and VM at d 118. Treatments had no effect on enteric CH4 emissions. The average daily gain (ADG) and total gain were greater in cattle fed MNVM than in cattle fed MN. Combination of monensin and virginiamycin altered the rumen microbial populations but did not decrease enteric CH4 emissions. However, it decreased forage dry matter intake without altering the ADG and total weight gain, leading to an increase in feed efficiency. Results from this study indicate an advantage in including feed additives combined in the diet of supplemented Nellore cattle grazing tropical grass during the rainy season.

The objective of the present study was to evaluate the potential of the dietary addition of neem (Azadirachta indica) leaf powder (NLP) when compared to monensin (MON) on ruminal fermentation, feed intake, digestibility, and performance of growing lambs. Eighteen Omani lambs (22.8 ± 2.18 kg of body weight (BW)) were equally divided into three groups (n = 6 lambs/group) for 90 days. Animals were fed an ad lib basal diet consisting of Rhodes grass (Chloris gayana) hay (600 g/kg) and a concentrated mixture (400 g/kg) offered twice daily. Experimental treatments were control (basal diet without supplements); MON (control plus 35 mg/kg DM as a positive control); and NLP (control plus 40 g/kg DM). Lambs fed NLP had reduced ruminal ammonia nitrogen concentrations, protozoal counts, total volatile fatty acid, and blood urea nitrogen concentrations compared to the control. Compared to MON, lambs fed NLP had increased ruminal acetate and decreased propionate proportions. Inclusion of NLP in the diet increased blood total protein, globulin, and liver enzyme concentrations in comparison with the control, which was similar to MON. The lamb’s final BW and average BW gain were also increased with the NLP relative to the control. Further, adding NLP to the diet increased the digestibility of crude protein compared to the control diet. In conclusion, adding NLP to the diet with 40 g/kg DM could be used as a promising phytogenic supplement for growing lambs with no detrimental effects on the ruminal fermentation profile, nutrient intake, or digestibility.

Objective Our objective was to evaluate subsequent feedlot performance and carcass characteristics of steers that previously grazed endophyte-infected fescue and received either a mineral only (MIN) supplement or a cumulative management (CM) strategy. Materials and Methods Grazing occurred in autumn and winter of 2018 and 2019 with feedlot finishing after grazing. Within year, 60 fall-weaned steers (282 ± 7.7 kg) were randomly assigned to either MIN (n = 3) or CM (n = 3) pastures. The CM strategy include a steroidal growth implant, monensin, and 1% BW (as-fed basis) of 1:1 corn gluten feed:soybean hull mix. During feedlot finishing, steers were penned to maintain pasture groups. Results and Discussion Steers receiving CM were heavier (P = 0.002) entering the feedlot and finished 40 d earlier than MIN (161 vs. 201 ± 5.7 d, P Implications and Applications A CM strategy increases weight of steers grazing toxic fescue. This additional weight can reduce the days required for feedlot finishing without influencing carcass characteristics. Improved grazing performance and fewer days for feedlot finishing may reduce environmental impact.

Our objectives were to evaluate the effects of prepartum monensin supplementation and dry-period nutritional strategy on the postpartum productive performance of cows fed monensin during lactation. A total of 102 Holstein cows were enrolled in the experiment (32 primiparous and 70 multiparous). The study was a completely randomized design, with randomization restricted to balance for parity, body condition score, and expected calving date. A 2 × 2 factorial arrangement of prepartum treatments was used; the variables of interest were prepartum feeding strategy [controlled-energy diet throughout the dry period (CE) vs. controlled-energy diet from dry-off to 22 d before expected parturition, followed by a moderate-energy close-up diet from d 21 before expected parturition through parturition (CU)] and prepartum monensin supplementation [0 g/t (control, CON) or 24.2 g/t (MON); Rumensin; Elanco Animal Health, Greenfield, IN]. Lactation diets before and after the dry period contained monensin at 15.4 g/t. During the close-up period, cows fed CU had greater DM and NEL intakes than cows fed CE. Calf BW at birth tended to be greater for cows fed CU than for those fed CE but was not affected by MON supplementation. Diet did not affect calving difficulty score, but cows supplemented with MON had an increased calving difficulty score. We found a tendency for a MON × parity interaction for colostral IgG concentration, such that multiparous MON cows tended to have lower IgG concentration than CON cows, but colostral IgG concentration for primiparous MON and CON cows did not differ. Postpartum milk yield did not differ between diets but tended to be greater for cows supplemented with MON. Milk fat and lactose content were greater for cows fed CU than for those fed CE, and lactose content and yield were increased for cows supplemented with MON. Solids-corrected and fat-corrected milk yields were increased by MON supplementation, but were not affected by diet. Overall means for postpartum DMI did not differ by diet or MON supplementation. The CU diet decreased the concentration of nonesterified fatty acids during the close-up period but increased it postpartum. Neither diet nor monensin affected β-hydroxybutyrate or liver composition. Overall, postpartum productive performance differed little between prepartum dietary strategies, but cows fed MON had greater energy-corrected milk production. In herds fed monensin during lactation, monensin should also be fed during the dry period.

Ninety crossbreed bulls (349.5 ± 8.25 kg initial weight) were used in an 87day trial to compare the effects of a blend of essential oils plus 25-hydroxy-Vit-D3 (EO + HyD) versus the combination of monensin with virginiamycin (MON + VM) on feedlot growth performance and carcass characteristics. Dietary treatments (nine replicates/treatment) were supplemented with 40 mg/kg diet dry matter of MON + VM (equal parts) or with 120.12 mg/kg diet dry matter of a combination of standardized mixture of essential oils (120 mg) plus 0.12 mg of 25-hydroxy-vitamin-D3 (EO + HyD). There were no treatment effects on dry matter intake (DMI, p = 0.63). However, the coefficient of variation in day-to-day DMI was greater for EO + HyD than for MON + VM (11.4% vs. 3.88%, p = 0.04). There were no treatment effects (p ≥ 0.17) on daily weight gain, gain-to-feed ratio, and estimated dietary net energy. Cattle supplemented with EO + HyD had greater Longissimus muscle area (7.9%, p < 0.01) and estimated retail yield (1.6%, p = 0.03), and tended to have heavier (1.7%, p = 0.10) carcass weight. Differences among treatments in dressing percentage, fat thickness, kidney–pelvic–heart fat, and marbling score were not appreciable (p > 0.10). It is concluded that growth performance response and dietary energetic are similar for finishing cattle supplemented with EO + HyD vs. MON + VM. However, compared with MON + VM, supplementation with EO + HyD during the finishing phase may improve carcass Longissimus area and carcass yield.

The suppressive effect of monensin as an ionophore-feed additive on enteric methane (CH4) emission and renewable methanogenesis were evaluated. To clarify the suppressive effect of monensin a respiratory trial with head cage was performed using Holstein-Friesian steers. Steers were offered high concentrate diets (80% concentrate and 20% hay) ad libitum with or without monensin, galacto-oligosaccharides (GOS) or L-cysteine. Steers that received monensin containing diet had significantly (p < 0.01) lower enteric CH4 emissions as well as those that received GOS containing diet (p < 0.05) compared to steers fed control diets. Thermophilic digesters at 55°C that received manure from steers fed on monensin diets had a delay in the initial CH4 production. Monensin is a strong inhibitor of enteric methanogenesis, but has a negative impact on biogas energy production at short retention times. Effects of the activity of coprophagous insects on CH4 and nitrous oxide (N2O) emissions from cattle dung pats were assessed in anaerobic in vitro continuous gas quantification system modified to aerobic quantification device. The CH4 emission from dungs with adults of Caccobius jessoensis Harold (dung beetle) and the larvae of the fly Neomyia cornicina (Fabricius) were compared with that from control dung without insect. The cumulative CH4 emission rate from dung with dung insects decreased at 42.2% in dung beetles and 77.8% in fly larvae compared to that from control dung without insects. However, the cumulative N2O emission rate increased 23.4% in dung beetles even though it reduced 88.6% in fly larvae compared to dung without coprophagous insects. It was suggested that the antibacterial efficacy of ionophores supplemented as a growth promoter still continued even in the digested slurry, consequently, possible environmental contamination with the antibiotics might be active to put the negative impact to land ecosystem involved in greenhouse gas mitigation when the digested slurry was applied to the fields as liquid manure.

This study was conducted to evaluate the growth performance and carcass characteristics of finishing steers fed diets containing different feed additives: control (CTL; no feed additives); monensin [26 mg/kg dry matter (DM); MON]; a blend of cinnamaldehyde, eugenol, and capsicum (120 mg of a commercial product/kg DM; XT), or the combination of monensin and the blend of cinnamaldehyde, eugenol, and capsicum (26 mg/kg DM and 120 mg of a commercial product/kg DM, respectively; MON + XT). A total of 860 steers [initial body weight (BW) = 334 kg] were fed the basal diet (7% alfalfa hay and 93% concentrate; DM basis) containing the treatments during 154 days. Feed additives did not affect final BW, DM intake, average daily gain, and feed efficiency of finishing steers (P ≥ 0.12). Dressing percentage was lower for MON + XT than MON and XT (P = 0.01). Feeding XT tended to increase the percentage of the carcass with a small marbling score compared to MON (P = 0.09). The proportion of carcass grading premium choice tended to be greater for steers fed MON compared to XT (P = 0.07). The feed additives evaluated herein did not affect the growth performance of finishing beef steers and had little effects on carcass characteristics.

Our objective was to evaluate the interaction of supplemental essential oils (EO) and monensin (MON) on performance and digestion. Two levels of EO (0 vs 0.011% Xtract®) and two levels of MON (0 vs 33 mg/kg) were evaluated in a 2 × 2 factorial arrangement. Treatment effects on 216-d growth performance were evaluated in 96 Holstein steers. Supplemental MON enhanced (P ≤ 0.05) ADG, DMI and gain efficiency. Without EO, MON improved (P

This study aimed to evaluate the associative effect of monensin and tannins on intake, feeding behaviour, digestibility, rumen kinetics, microbial protein synthesis and nitrogen balance. In a 2 × 4 factorial arrangement, 8 rumen cannulated Nellore cows were distributed in 2 contemporary 4 × 4 Latin squares and received 8 diets that differed in the level of tannins (0.00, 0.75, 1.50 and 2.25% DM) and presence of monensin. Monensin was daily administered to each cow in one square (about 32 mg/kg DM). No interaction between monensin and tannins was observed (p > .05). Tannins linearly reduced feed intake, but linearly increased daily eating time (p < .05), although these did not alter the number of meals. Monensin increased CP digestibility by 6% (p = .0387) while tannins linearly reduced digestibility of DM, CP, OM and TDN, whereas the reduction was quadratic for ADF and NDF. Tannins linearly reduced the rumen disappearance rate by linearly reducing both passage and digestion rates. Tannins also linearly reduced urinary urea, though neither additive affected microbial protein synthesis. Monensin reduced the proportion of N excreted in faeces, whereas tannins linearly increased faecal N and linearly reduced both urinary and retained N. Monensin and tannins have shown independent effects on feeding behaviour, feed intake, digestive parameters, microbial protein synthesis and N balance, but they did not improve nutrient usage, although monensin alone has shown to have potential to promote N utilisation. Tannins may play an important role in reducing the excretion of N in urine.Highlights Tannins reduce the efficiency of nutrient usage in cattle. Tannins change the pathway of the excretion of the feeding nitrogen. The emission of N2O from the urine may be reduced by the use of tannins in cattle feeding.

The objective of this study was to evaluate growth and performance of postweaning heifers supplemented with monensin (MON), sodium butyrate (SB), or the combination of MON and SB (MSB) compared with heifers not receiving these feed additives. Forty Holstein heifers [mean age 84.2 ± 1.2 d; body weight (BW) 99.8 ± 10.8 kg (mean ± SD)] were housed in a freestall barn, blocked by birth date, and randomly assigned to 1 of 4 treatments in a randomized complete block design. Treatments were (1) 100 g of soybean meal carrier (control; CON); (2) 0.75 g of SB/kg of BW + carrier (SB); (3) 1 mg of MON/kg of BW + carrier (MON); (4) 1 mg of MON/kg of BW + 0.75 g of SB/kg of BW (MSB). Data were analyzed using single degree of freedom contrasts evaluating CON versus additives (ADD), SB versus MON, and SB and MON versus MSB. Treatments were hand-mixed daily. Feed and orts were measured daily and frozen at -20°C. Orts samples were subsampled for dry matter (DM) determination, and total mixed ration samples were taken weekly and composited monthly for DM and nutrient analysis. Initial BW, heart and paunch girths, body length, blood samples, and fecal coccidia counts were measured before the start and weekly during the 12-wk trial. Blood samples were analyzed for glucose, plasma urea nitrogen (PUN), and ketone concentrations. Apparent total-tract nutrient digestibility was determined from d 21 to 27 and from d 63 to 69 using acid detergent insoluble ash as a marker. Daily dry matter intake (DMI) and metabolizable energy intake were increased in ADD compared with CON, and average BW, final BW, and heart girth tended to increase. Whereas MSB tended to be greater than SB and MON for heart girth, feed efficiency was greater with MON compared with SB. Compared with CON, ADD decreased coccidia counts. No effect of treatment on PUN was detected. Monensin and SB tended to have greater plasma glucose than MSB did. Average blood ketone concentrations were greater with ADD versus CON, in SB versus MON, and in MSB versus SB and MON. During the wk-3 digestibility phase, DMI tended to be greater in heifers fed SB versus MON, as well as in heifers fed MSB versus SB and MON. Digestibility of nutrients were similar, except that starch digestibility was increased in heifers fed MSB versus SB and MON. During the wk-9 digestibility phase, DMI and digestibility of nutrients were similar, except NDF, which tended to be greater in CON than in ADD. Overall, ADD resulted in positive growth and reduced coccidia compared with CON.

Objective Use of monensin during the stocker phase of production has been suggested as a possible cause of reduced response to monensin during finishing. Experiments were conducted to determine the carryover effects of monensin supplementation during the stocker phase and effects of feeding monensin during the finishing phase on performance and efficiency of beef steers. Materials and Methods Steers were fed hay or grazed cool-season annuals or bermudagrass in Arkansas before finishing in Canyon, Texas (blocks 1 and 2) or Stillwater, Oklahoma (block 3). Treatments were arranged as a 3 × 2 factorial with 3 monensin doses during the stocker phase (0, 882, or 1,764 g/t offered in a free-choice mineral) and 2 levels during finishing (0 or 37.5 mg/kg of diet DM). There were no block × treatment interactions (P ≥ 0.19) for performance or carcass measurements; therefore, data were pooled across blocks and finishing locations. Results and Discussion Stocker × finishing treatment interactions were not observed for finishing performance and efficiency data (P ≥ 0.50). There was no carryover effect on overall finishing performance or efficiency. Cattle consuming monensin during the finishing phase had decreased (P Implications and Applications Supplementation of monensin to stocker cattle before finishing did not affect subsequent finishing efficiency response to monensin during finishing. Providing monensin in finishing diets still decreases DMI and improves feed efficiency of finishing cattle.

Coccidiosis is a high-prevalence disease that annually entails huge costs for the poultry industry. Control of coccidiosis in poultry production is based on the use of coccidiostats and vaccines. However, along with the problem of drug resistance, there is a concern about food safety and drug residues in poultry products. The objective of this study was to evaluate the effect of sodium bisulfate (SBS) in comparison with monensin (M) and their combination (SBSM) effects on controlling coccidiosis in broilers. In a randomized design, 300 chickens (Ross 308) were divided into 5 treatments and 4 replications (15 birds per replicate). All birds, except the negative control (NC), were orally inoculated with 4 Eimeria species on 14 D of age. Treatments included were as follows: NC, an unsupplemented basal diet, nonchallenged; positive control, a basal diet unsupplemented, challenged with Eimeria spp; a basal diet supplemented with 5 g/kg of SBS; a basal diet supplemented with 1 g/kg of M; and a basal diet supplemented with 5 g/kg SBS and 1 g/kg M (SBSM). Oocyst shedding per gram (OPG) of the faecal sample from each experimental unit was counted on 5 to 14 D after inoculation. Two chicks from each experimental unit were euthanized to investigate intestinal lesions on day 5 after inoculation. The NC birds showed the highest BW gain and the lowest feed conversion ratio. The birds in the SBSM group had improved feed consumption compared with the M group in the prechallenge period (P < 0.05). All supplemented treatments resulted in a significant decrease in OPG. The M and SBSM treatments showed more efficacy than the SBS group (P < 0.05) in reducing OPG. There was a significant reduction in cecal lesions owing to supplementation with SBS, but the effect of SBS in the upper part of the intestine was lower than the M and SBSM groups (P < 0.05). Based on the results of this study, SBS has protective effects against coccidiosis in ceca, and the combination of M and SBS (SBSM) did not show any further improvement effect compared with M alone on the control of coccidiosis.

The amount of milk Canadian dairy farmers produce is limited to a production quota expressed in milk fat. Because milk economic value is primarily based on fat and protein, it can be advantageous to decrease the milk fat to protein ratio. Monensin sodium has been suggested to reduce milk fat proportion and outputs, but not milk protein. Publications using lactating dairy cows were utilized to assess predictability of production responses to monensin feeding based upon their base production characteristics and diet composition. Predicted animal output changes due to monensin had poor fits with low r2 (0.31–0.44) and unevenly distributed residuals. Further assessment revealed that cow characteristics, and diets, were not independent of monensin feeding level. Thus, the 43 comparisons were clustered into levels of 10–12, 14–18, or 20–24 mg kg−1 of diet dry matter (DM). Milk fat yield reductions due to monensin differed (P −1 DM), or tended to differ (P = 0.057; 20–24 mg kg−1 DM), from zero (i.e., no change). Monensin addition to total mixed rations of lactating dairy cows negatively impacted milk fat yield to a greater extent than milk protein.

Summary: This study assesses the efficacy of 2 different potentiated ionophores (monensin and narasin) and a chemical (nicarbazin, a shuttle) in program with narasin to control coccidiosis in challenged male broilers through the evaluation of performance and macroscopic lesions of internal organs. A total of 4,400 broiler chicks were housed in 44 floor pens of 100 birds each; birds of the first group were fed a narasin/nicarbazin (NN)–containing diet from 0 to 27 D of age followed by narasin diet until market age, and those of group 2 were fed a monensin/nicarbazin diet followed by narasin ration for the same trial periods. The coccidia challenge was performed at day 1 by the inclusion of a proven Eimeria-infected litter in the bedding of all floor pens followed by an oral challenge using a commercial cocci vaccine at 7 D of age with a concentration of 11 times the vaccine dose. Although results showed that NN and monensin/nicarbazin treatments both demonstrated efficacy at reducing coccidian lesions, NN significantly increased BW and reduced feed conversion ratio (P < 0.05) at 27 (1,405 vs. 1284 g and 1.458 vs. 1.566, respectively) and at 33 D of age (2,178 vs. 2,026 g and 1.549 vs. 1.642, respectively). Weight and weight percentages of the ready-to-cook carcass and carcass cutup parts were significantly improved by NN. Narasin/nicarbazin inclusion in diet for 0 to 27 D followed by narasin until market weight was a successful strategy because, in addition to preventing and controlling coccidiosis, it improved performance of broiler chickens.

Our previous work indicated that feeding oregano essential oil (OEO) in combination with monensin (MON) may not be mutually beneficial to dairy calf growth performance. To evaluate this observation further, a 240-d long-term growth experiment was conducted using 12 young growing Holstein bulls using a 2 × 2 factorial treatment arrangement. Main factors were OEO and MON arranged in 4 individual treatments: (1) ration fed without OEO or MON (control), (2) OEO fed at 26 mg/kg of dry matter (DM), (3) MON fed at 25 mg/kg of DM, and (4) OEO and MON fed in combination (OEO+MON). Holstein bulls were 70 d of age and similar in body weight (BW; 93.3 ± 4.54 kg) and individually fed for 240 d. The targeted feeding rates of OEO and MON were blended into 200 g of concentrate and top dressed each morning to a corn stalklage-based ration. Body weights, frame measurements, and blood samples were collected monthly. Interactions of OEO by MON were detected for BW, BW gain, average daily gain, and a trend for feed conversion. Bulls fed OEO or MON demonstrated greater final BW (368, 385, 381, and 358 kg for control, OEO, MON, and OEO+MON, respectively), and BW gains (278, 292, 285, and 265 kg) and average daily gain (1.16, 1.22, 1.19, 1.11 kg/d) were greatest for bulls fed OEO or MON compared with bulls fed OEO+MON; bulls fed the control were intermediate and similar to bulls fed MON. Intake of DM was greater for bulls fed OEO (6.55, 6.99, 6.60, and 6.42 kg/d) compared with bulls fed remaining treatments. Frame growth gain measurements for heart girth, abdominal girth, withers height, body length, and cannon bone circumference were similar for bulls fed all treatments. Serum triglyceride (0.23, 0.25, 0.28, and 0.24 mmol/L) concentrations were greater for bulls fed MON compared with bulls fed the control and OEO+MON, and bulls fed OEO were intermediate and similar. Cholesterol (2.06, 2.29, 2.20, and 2.07 mmol/L) concentrations were greater for bulls fed OEO compared with bulls fed the control and OEO+MON, and bulls fed MON were intermediate and similar. Serum antioxidant measurements were similar for bulls fed all treatments. Serum IgA, IgG, and IgM concentrations were similar for bulls fed all treatments. Feeding OEO or MON separately can improve growth performance of growing Holstein bulls. We do not know why the combination of OEO and MON is antagonistic to growth performance of Holstein bulls. However, these technologies should not be fed in combination to growing dairy cattle.

Objective Two experiments were conducted to evaluate conventional (tylosin, monensin, steroidal hormone growth implants, and β-adrenergic agonist) and nonconventional [direct-fed microbial (DFM), fibrolytic enzyme (ENZ), and flavoring agent (OLEO)] growth-enhancing technologies on the performance of finishing beef feedlot steers. Materials and Methods In Exp. 1, 384 crossbred beef steers (499 ± 28.6 kg of BW) were randomly assigned to 8 feedlot pens equipped with a system for measurement of individual feed intake. Steers were assigned to 1 of 8 diets with or without hormonal implants in a completely randomized 8 × 2 factorial treatment structure, with diet and implant as main factors (24 implanted steers and 24 nonimplanted steers per pen). The diet treatments were (1) nonmedicated diet (NMD); (2) NMD+DFM; (3) NMD+ENZ; (4) NMD+OLEO; (5) NMD+DFM+ENZ+OLEO; (6) medicated diet containing monensin, tylosin, and β-adrenergic agonist (CVD); (7) CVD+DFM+ENZ, and (8) CVD+DFM+ENZ+OLEO. In Exp. 2, 960 crossbred beef steers (426 ± 39.9 kg of BW) were randomly allocated to 1 of 4 treatments (12 pens per treatment): (1) natural (no antibiotics, ionophores, growth implants, or β-adrenergic agonists; NAT); (2) NAT+OLEO; (3) medicated diet containing ionophore and tylosin (CONV); and (4) CONV with hormonal implant and β-adrenergic agonist (CONV+HI/BA). Results and Discussion Improvement (P 0.10) in growth performance. Applications Eliminating conventional growth-enhancing technologies reduced feed efficiency and growth performance, consequently undermining the sustainability of beef production systems.

Objective The objective of this research was to determine the effect of differential monensin (Rumensin, Elanco Animal Health, Greenfield, IN) intake in a free-choice loose mineral on performance of grazing beef steers. Material and Methods Treatments consisted of offering ad libitum access to minerals (AMPT-A, ADM Animal Nutrition, Quincy, IL) supplying 0 (0M), 882 (800M), or 1,764 (1600M) g of monensin/t with targeted daily monensin intakes of 0, 100, or 200 mg of monensin per steer. Steer calves (n = 605, BW = 278 ± 27 kg) were fed hay with a hand-fed supplement (block 1); grazed wheat (Triticum aestivum) pasture (blocks 2, 3, and 6); or bermudagrass (Cynodon dactylon) pasture (blocks 4 and 5). There were no treatment × diet interactions (P ≥ 0.97); therefore, data were pooled across blocks for statistical analysis. Results and Discussion Steers offered 800M and 1600M had greater (P ≤ 0.02) final BW, ADG, and total BW gain compared with 0M steers fed mineral without monensin. Mineral intake decreased linearly (P Implications and Applications Monensin supplementation improved growth performance compared with an unmedicated control within the doses observed in this experiment and regardless of basal forage quality. Intake of a self-fed monensin-containing mineral can be decreased by at least 50% without affecting performance response to monensin of steers on forage-based diets.

Made available in DSpace on 2020-12-11T21:11:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Oligo Basics USA, LLC (Cary, NC) North Carolina Agricultural Foundation, Inc. (Raleigh, NC) USDA-NIFA Project Two experiments were conducted to evaluate the effects of functional oils containing cashew nutshell and castor oil on turkey performance and intestinal morphology. In experiment 1, 585 hatchlings were randomly placed in 15 replicate floor pens, (13 poults/pen) with recycled litter and provided feed and water ad libitum. Birds were randomly assigned to 3 dietary treatments from 1 to 12 wk: nonmedicated control, 0.15% functional oils, and 66-ppm monensin. From wk 13 to 20, each initial treatment group was further divided into 3 treatments-control (no additive), 0.15% of functional oils, or 20 ppm of virginiamycin to produce 9 different treatments, 5 replicate pens per treatment. Data on feed weights were collected weekly, and body weight bi-weekly. At termination (20 wk), birds were euthanized, and their meat was processed to determine mass of carcass sections and meat quality, while intestinal samples were collected for histology. In experiment 1, toms fed monensin or functional oils were 10.5 and 4.5% heavier (P < 0.05), respectively, than the controls at 12 wk. Birds fed monensin had a 4% improvement (P < 0.05) in feed conversion as compared to the other treatments. Neither virginiamycin nor the functional oils affected bird performance when fed from 13 to 20 wk. The jejunum villi surface area at 3 wk was most enhanced (P < 0.05) for the poults fed monensin. Supplementation with functional oils significantly reduced leg yield and thiobarbituric-acid reactive substances of white meat after 7 D of storage (P < 0.05). There were no effects on performance or carcass characteristics in experiment 2. While additional confirmatory studies are needed, functional oils in the diet of turkey toms may be a viable alternative to antibiotic growth promotants. NCSU, Prestage Dept Poultry Sci, Raleigh, NC 27695 USA Sao Paulo State Univ, Sao Paulo, SP, Brazil ARS, USDA, Market Qual & Handling Res Unit, Raleigh, NC 27695 USA Oligo Basics USA LLC, Cary, NC 27519 USA Sao Paulo State Univ, Sao Paulo, SP, Brazil USDA-NIFA Project: NC06343

Objective The objectives of this research were to determine the effects of medicated feed additives on performance, health, and coccidia infection in newly received calves classified as high risk for bovine respiratory disease infection. Materials and Methods Growing steers and bulls were received to evaluate the effects of supplying 20 mg/calf bambermycin or 0.77 mg/kg of BW monensin in receiving supplements (20% CP and 78% TDN) compared with a nonmedicated supplement. Fecal samples were collected from 6 steers/pen on d 0, 14, and 28 to evaluate coccidia infection. Water in the bambermycin pens was treated from d 14 to 19 with 10 mg/kg of BW amprolium. Steers remained on treatment for 56 to 84 d for block 1, 49 d for block 2, and 42 d for block 3, depending on availability of wheat forage for subsequent grazing. Results and Discussion There were no differences (P ≤ 0.36) in morbidity, mortality, or animals identified as chronically morbid. Monensin decreased coccidia (P ≤ 0.03) compared with control and bambermycin, which did not differ (P = 0.85). At the end of receiving, BW and ADG for control calves was less than (P ≤ 0.04) for calves receiving bambermycin and monensin. Implications and Applications Monensin or bambermycin can effectively improve BW gain of calves at high risk for bovine respiratory disease. Monensin provides superior control of natural infection of coccidia based on fecal oocyst counts compared with bambermycin. Neither medicated feed additive altered morbidity or mortality due to bovine respiratory disease or treatment response to bovine respiratory disease.

A clinical study was made into the abilities of nicarbazin and monensin and a nicarbazin + monensin combination to control Eimeria acervulina, E. maxima, and E. tenella in chickens. When included i...

Objective The objective was to assess activity of steers grazing tall fescue pastures varying in toxicity with and without a combination management practice including supplemental feed, ionophore, and a steroidal implant. Materials and Methods Activity of steers was monitored using IceQube (IceRobotics Ltd., Edinburgh, UK) accelerometers. Steers grazed 1 of 15 pastures differing in ergovaline (EV) in spring 2016. For 7 pastures, steers were offered mineral-only (MIN) management (MGMT). In the remaining pastures, steers received a cumulative (CM) MGMT strategy including 1% BW, 1:1 corn gluten feed:soybean hulls, 150 mg/head per day monensin, and a steroidal implant containing 40 mg of trenbolone acetate, 8 mg of estradiol, and 29 mg of tylosin tartrate. Physical activities—lying bouts, steps, and standing time—were reported in 2 periods: period 1 (27 d) and period 2 (26 d). Results and Discussion Period 1 lying bouts were not different for MGMT (P = 0.11) or EV (P = 0.26). Period 2 lying bouts exhibited a MGMT × EV interaction (P = 0.02). Time steers spent standing was not different between CM and MIN during period 1 (P = 0.79) but differed during period 2 (P Implications and Applications Behavioral changes due to EV and MGMT appeared more prevalent during period 2 when warmer weather and changing forage quality would be expected to worsen the effects of fescue toxins. The CM may elicit greater satiety or reduce heat stress. Strategies that improve productivity of cattle on toxic fescue may also improve welfare as expressed through physical activity changes.

Objective This study examined the effects of feeding essential oils, benzoic acid, or both, as a replacement for monensin and tylosin, on finishing cattle growth performance, carcass characteristics, meat quality, and sensory properties. Materials and Methods Crossbred steers (n = 68; BW = 539 ± 36 kg) were fed 1 of 5 dietary treatments: (1) control (CON; no antibiotics fed); (2) monensin and tylosin (M/T; monensin supplemented at 33 mg/kg on a DM basis; tylosin supplemented at 11 mg/kg on a DM basis); (3) essential oils (EO; supplemented at 1.0 g/steer per day); (4) benzoic acid (BA; supplemented at 0.5% on a DM basis); and (5) combination (COMBO; essential oils supplemented at 1.0 g/steer per day and benzoic acid supplemented at 0.5% on a DM basis). Steers were fed their designated diets for the last 98 d of the finishing period using an Insentec feeding system (Insentec B.V., Marknesse, the Netherlands). Results and Discussion A tendency for improved G:F (P = 0.07) was observed; specifically, M/T steers tended to have greater feed efficiency compared with CON, EO, and COMBO steers. Dietary treatment affected (P ≤ 0.05) lipid content in the longissimus thoracis and the following trained sensory attributes: tenderness, chewiness, juiciness, and beef flavor. Specifically, longissimus thoracis steaks from CON steers had less lipid content, whereas longissimus thoracis steaks from CON and COMBO steers were tougher, chewier, and less juicy compared with other treatments. Implications and Applications Results from this study suggest that growth performance was similar for steers supplemented with essential oils, benzoic acid, or both versus CON steers, and beef quality from alternative treatments was not compromised.

This study evaluated the inclusion of concentrate and monensin, salinomycin and flavomycin in sheep diets on intake, digestibility, in situ degradability, ruminal variables and nitrogen balance. Five sheep in a latin square received the treatments: HAY (hay only), CONT (hay + concentrate), MON (hay + concentrate + monensin), SALI (hay + concentrate + salinomycin), and FLAV (hay + concentrate + flavomycin). Hay was offered ad libitum , concentrate, 20 g kg -1 of body weight (BW), and additives, 0.75 mg kg -1 of BW. The treatments with the concentrate (CONT, MON, SALI and FLAV) showed increased ( P ≤0.05) on intake, digestibility, total VFA, propionate and butyrate proportions, N-NH 3 , and nitrogen balance, and decreased ( P ≤0.05) DM and NDF degradability, acetate proportion, acetate:propionate ratio, and rumen pH compared to the HAY. The comparison between the outcome effects from additives with the CONT showed that the acetate proportion and acetate:propionate ratio was only reduced by MON ( P ≤0.05). MON and SALI increased ( P ≤0.05) the propionate proportion. The proportion of butyrate was increased with the inclusion of FLAV and reduced with MON and SALI. Only MON reduced the production of N-NH 3 ( P ≤0.05). Other variables showed no effects from additives ( P >0.05) in relation to the CONT. The inclusion of the concentrate in sheep diets caused alterations on intake, digestibility, ruminal variables (VFA, pH, and N-NH 3 ) and nitrogen balance. However, the additives only altered the ruminal variables (VFA and N-NH 3 ) and the greatest effects were observed with MON.

Objective Two experiments evaluated the effects of supplemental monensin on growth and physiology of early-weaned beef calves grazing ryegrass (Exp. 1) or bahiagrass (Exp. 2). Materials and Methods Brangus calves were weaned at 3 mo of age, stratified by sex and BW, and randomly assigned into 1 of 8 pastures (2 steers and 2 heifers per pasture per year) of ryegrass (Exp. 1; n = 2 yr) or bahiagrass (Exp. 2; n = 1 yr) from d 0 to 84. Treatments were assigned to pastures (4 pastures per treatment per year) and consisted of concentrate supplementation at 1 or 2% of BW (DM basis) in Exp. 1 and 2, respectively, with or without 20 mg of monensin/kg of DMI. Results and Discussion Herbage nutritive value and allowance did not differ (P ≥ 0.23) between treatments in Exp. 1 and 2, but herbage mass tended (P = 0.10) to increase by 5% for monensin versus control calves in Exp. 1. Calf overall ADG increased (P ≤ 0.005), whereas fecal coccidia egg count on d 84 decreased (P ≤ 0.0004), for monensin versus control calves in Exp. 1 and 2. Monensin supplementation tended (P ≤ 0.08) to increase plasma insulin concentrations in Exp. 1 and 2 and increased (P ≤ 0.03) plasma IGF-1 concentrations on d 56 in Exp. 1 and plasma urea nitrogen concentrations on d 84 in Exp. 2. Implications and Applications Supplemental monensin led to subtle changes to physiological parameters associated with energy metabolism, reduced coccidiosis infestation, and promoted the growth performance of early-weaned calves grazing ryegrass and bahiagrass pastures.

Because of their antimicrobial properties, essential oils and their components have been suggested as alternatives to other antimicrobials (e.g., monensin) that are commonly fed to ruminants to improve nutrient utilization and enhance feed efficiency and milk performance. In this study, we evaluated the potential of oregano oil and its main component (carvacrol) as rumen modifiers. For this purpose, 8 ruminally cannulated lactating dairy cows (92 ± 11 d in milk, 36.5 ± 7.6 kg of milk yield, and 703 ± 74 kg of body weight) were used in a double 4 × 4 Latin square (28-d periods). Cows were fed 1 of the 4 following treatments: (1) control (CTL, no additive); (2) monensin [MON, 24 mg/kg of dry matter (DM)]; (3) oregano oil (ORE, 50 mg/kg of DM); and (4) carvacrol (CAR, 50 mg/kg of DM). Cows were fed (ad libitum intake) a total mixed ration consisting of 60% forages (corn silage and alfalfa silage) and 40% concentrates, on a DM basis. Feeding ORE and CAR had no effect on nutrient total-tract apparent digestibility, N utilization, rumen fermentation (i.e., pH, ammonia, volatile fatty acids), protozoa counts, or milk performance. Feeding MON increased the molar proportion of propionate and tended to increase total-tract apparent digestibility of crude protein. None of the feed additives evaluated affected enteric methane production (491 g/d, 21.1 g/kg of DM intake, 6.14% of gross energy intake on average). Milk fatty acid composition was not changed by ORE or CAR, but MON increased the proportion of trans-10 18:1, an intermediate of ruminal biohydrogenation. Thus, when included at 50 mg/kg of dietary dry matter, neither oregano oil nor carvacrol favorably altered rumen fermentation, improved nutrient utilization or milk performance, or mitigated enteric methane emissions in dairy cows.

Greenhouse gas emissions, such as enteric methane (CH4) from ruminant livestock, have been linked to global warming. Thus, easily applicable CH4 management strategies, including the inclusion of dietary additives, should be in place. The objectives of the current study were to: (i) compile a database of animal records that supplemented monensin and investigate the effect of monensin on CH4 emissions; (ii) identify the principal dietary, animal, and lactation performance input variables that predict enteric CH4 production (g/d) and yield (g/kg of dry matter intake DMI); (iii) develop empirical models that predict CH4 production and yield in dairy cattle; and (iv) evaluate the newly developed models and published models in the literature. A significant reduction in CH4 production and yield of 5.4% and 4.0%, respectively, was found with a monensin supplementation of ≤24 mg/kg DM. However, no robust models were developed from the monensin database because of inadequate observations under the current paper’s inclusion/exclusion criteria. Thus, further long-term in vivo studies of monensin supplementation at ≤24 mg/kg DMI in dairy cattle on CH4 emissions specifically beyond 21 days of feeding are reported to ensure the monensin effects on the enteric CH4 are needed. In order to explore CH4 predictions independent of monensin, additional studies were added to the database. Subsequently, dairy cattle CH4 production prediction models were developed using a database generated from 18 in vivo studies, which included 61 treatment means from the combined data of lactating and non-lactating cows (COM) with a subset of 48 treatment means for lactating cows (LAC database). A leave-one-out cross-validation of the derived models showed that a DMI-only predictor model had a similar root mean square prediction error as a percentage of the mean observed value (RMSPE, %) on the COM and LAC database of 14.7 and 14.1%, respectively, and it was the key predictor of CH4 production. All databases observed an improvement in prediction abilities in CH4 production with DMI in the models along with dietary forage proportion inclusion and the quadratic term of dietary forage proportion. For the COM database, the CH4 yield was best predicted by the dietary forage proportion only, while the LAC database was for dietary forage proportion, milk fat, and protein yields. The best newly developed models showed improved predictions of CH4 emission compared to other published equations. Our results indicate that the inclusion of dietary composition along with DMI can provide an improved CH4 production prediction in dairy cattle.

The effects of a blend of encapsulated organic acids with essential oils (EOA) as an alternative to antimicrobial growth promoter (AGP) on growth performance and gut health of Eimeria spp./Clostridium perfringens (C. perfringens) in chickens infected with necrotic enteritis (NE) broilers was investigated. A total of 432 male Arbor Acres broilers (1-day-old) were randomly distributed into 6 treatment groups, namely noninfected negative control (A); NE-infected positive control (D); NE-infected broiler chickens fed a basal diet supplemented with 250 mg/kg bacitracin methylene disalicylate (BMD) plus 90 mg/kg monensin; and NE-infected broiler chicken fed 200; 500; and 800 mg/kg EOA (E, F, G, and H group). Feeding EOA at 200 and 500 mg/kg considerably improved the feed conversion ratio, reduced gut lesions, serum fluorescein isothiocyanate dextran level, and C. perfringens load in the caecum and liver of the NE-infected broiler chickens. This feed was similar to AGP. Furthermore, the increased villous height-to-crypt depth ratio and goblet cells counts, upregulated claudin-1, glucagon-like peptide-2 (GLP-2), insulin-like growth factor-2 (IGF-2) mRNA gene expression, downregulated occludin, zonula occludens-1 (ZO-1), toll-like receptor (TLR-4), interleukin (IL-1β), interferon γ (IFN-γ), TNF receptor-associated factor 6 (TRAF-6), tumor necrosis factor superfamily member 15 (TNFSF15), and Toll-interacting protein (Tollip) genes expression in the jejunum were observed in the NE-infected broiler chickens that received EOA at 200 and 500 mg/kg compared with those of the single NE-challenged groups without EOA supplementations (P < 0.05). The 16S analysis revealed that EOA supplemented with 200 or 500 mg/kg enriched relative abundance of Lactobacillus, unclassified_Lachnospiraceae, and Enterococcus, and carbohydrate metabolic pathways but suppressed unclassified_Erysipelotrichacease and organismal systems involved in the immune system (P < 0.05). Feeding EOA could alleviate NE-induced gut impairment and growth depression and modulate cecal microbiota composition, which has potential as antimicrobial alternatives.

Ninety young crossbreed bulls (approximately 25% Zebu breeding with the remainder represented by continental and British breeds in various proportions, initial weight=228.04±7.06 kg) were used in a 84-day feeding trial to assess the effects of treatments in feedlot cattle fed transition diets during high ambient temperatures. Treatments consisted of a steam-flaked corn-based diets (average 1.95 Mcal ENm/kg) supplemented with: 1) 20 mg monensin/kg diet (MON, Rumensin, Elanco Animal Health, Indianapolis, IN], and 2) 100 mg of blend of essential oils /kg diet plus 0.1 mg 25-hydroxy-vitamin-D3/kg diet (EO+HyD; CRINA® Ruminants and HyD®, DSM Nutritional Products, Basel, Switzerland). Both dry matter intake (DMI) and climatic variables were measured daily and the temperature humidity index (THI) was estimated. Daily maximal THI remained over 80 during the whole trial (avg. THI = 82.67). Cattle supplemented with EO+HyD increased average daily gain in 8.7% (1.446 vs. 1.320 kg/day, P < 0.01), gain-to-fed ratio in 4.5% (0.199 vs. 0.190; P = 0.03), final weight in 10.05 kg (349.48 vs. 339.43; P = 0.04) and tended (P = 0.07) to shown greater dietary net energy (2.5%) and observed-to-expected dietary NE ratio (3%). Even when EO+HyD tended to increase (4.3%; P = 0.06) DM intake, intake pattern variation were not different (P = 0.38) between MON and EO+HyD (Figure 1). Then, difference in ADG and final BW between MON and EO+HyD was not only a reflection of difference in energy intake, was also caused by difference in efficiency of energy utilization during conditions of high ambient temperature (a reduction of 7% in the estimated increase of coefficient of maintenance by heat load). Results indicate that supplementation with a combination of essential oil blend plus 25-hydroxy-vitamin-D3 can have greater beneficial effects than supplemental monensin on daily weight gain, final weight and feed intake during initiation-transition phase of cattle raised under high ambient temperature.

The objective of this study was to evaluate diets containing monensin (MON) associated or not with virginiamycin (VM) or functional oil based on cashew nut shell and castor beans (FOcc) for beef cattle in feedlots on nutritional (intake and digestibility) and productive parameters. A total of 1410 non-castrated Nellore cattle were selected, with an average age of 18 months and with an initial mean body weight (BW) of 305 ± 41.52 kg. The diet showed a roughage to concentrate ratio of 23:77, with the supply of corn silage as a source of roughage. The following additive inclusions in the diet were evaluated: (1) MON: 27 mg MON/kg dry matter (DM); (2) MON + VM: 22 mg MON/kg DM + 19 mg VM/kg DM; and (3) MON + FOcc: 22 mg MON/kg DM + 500 mg FOcc/kg DM. Statistical analyses were obtained through a linear model using initial BW and days of feedlot as covariables and comparisons between treatments using mutually orthogonal linear contrasts with a 5% significance level. The association or not of MON with VM or FOcc does not affect any of the nutritional and productive parameters evaluated. Animals that receive diets with MON + VM have higher average daily gain and feed efficiency (FE) than those that receive MON + FOcc without showing differences in nutritional parameters. The supply of MON associated with VM or FOcc does not increase intake and productive performance and, consequently, efficiency of feedlot beef cattle. However, in the case of use associated with MON, the VM provides greater performance than FOcc without changing food intake.

Simple Summary The transition period is a challenging time, which combines a massive increase in nutrient requirements and leads to a negative energy balance. Therefore, disorders related to negative energy balance, such as ketosis, are more frequent. In addition, in this period, oxidative stress increases, favoring immune suppression functions and inflammation, which may lead to increased susceptibility to other diseases such as metritis and mastitis. Therefore, the combination of ionophores, such as monensin, that mitigate the accentuated negative energy balance; vitamin A, which plays an important role in supporting the immune system; and a high level of crude protein might improve immune parameters in dairy cows in the transition period. This study demonstrated that monensin and vitamin A supplementation and high crude protein levels enhanced some vitamin status and inflammatory markers when used during the late prepartum period. Abstract The objective of this study was to determine the effect of feeding different combinations of dietary vitamin A supplementation (0 or 110 IU/kg body weight), protein (10.3% or 12.2%), and an ionophore (monensin at 0 or 400 mg/day) on retinoid metabolism and immune function of dairy cows. Eighty multiparous Holstein dairy cows were studied from d −35 to +21 relative to expected parturition in a complete randomized block design with a 2 × 2 × 2 factorial arrangement of treatments. The significance of treatments was declared at p ≤ 0.05. Dairy cows receiving high crude protein (CP) diets with monensin had a greater retinol-binding protein serum concentration than cows receiving high CP diets without monensin (p = 0.04). Animals supplemented with vitamin A showed lower SCC (p = 0.04) and a higher thiobarbituric acid reactive substances concentration (p = 0.06) than cows non-supplemented. Moreover, cows receiving low crude protein diets had a greater haptoglobin concentration (p = 0.01). In addition, cows fed a high crude protein diet had a greater TNF-α expression in peripheral blood mononuclear cells (p = 0.04). Animals fed diets without monensin had a greater serum haptoglobin on day 3 postpartum than those fed monensin (p = 0.01). Moreover, dietary vitamin A increased serum 13-cis retinoic acid postpartum. We conclude that vitamin A, crude protein levels, and monensin fed during the close-up period affect milk somatic cell count, some vitamin statuses, and inflammatory markers during early lactation.

Previous research has shown that the brown seaweed Ascophyllum nodosum (ASCO) has antimicrobial and antioxidant properties and also increases milk I concentration. We aimed to investigate the effects of supplementing ASCO meal or monensin (MON) on ruminal fermentation, diversity and relative abundance of ruminal bacterial taxa, metabolism of I and As, and blood concentrations of thyroid hormones, antioxidant enzymes, and cortisol in lactating dairy cows. Five multiparous ruminally cannulated Jersey cows averaging (mean ± standard deviation) 102 ± 15 d in milk and 450 ± 33 kg of body weight at the beginning of the study were used in a Latin square design with 28-d periods (21 d for diet adaptation and 7 d for data and sample collection). Cows were fed ad libitum a basal diet containing (dry matter basis) 65% forage as haylage and corn silage and 35% concentrate and were randomly assigned to 1 of the following 5 dietary treatments: 0, 57, 113, or 170 g/d of ASCO meal, or 300 mg/d of MON. Supplements were placed directly into the rumen once daily after the morning feeding. Diets had no effect on ruminal pH and NH

Bu çalışmada, Urtica dioica, Matricaria chamomilla ve Vitex agnus-castus’un yüksek fenolik içerikli kuru ekstraktlarının normal koşullar ve asidoz koşulları altında rumen mikrobiyal fermentasyonu üzerine monensin ile karşılaştırmalı etkilerinin Rumen Similasyon Tekniği (RUSITEC) kullanılarak araştırılması amaçlanmıştır. Deneme grupları, negatif kontrol (katkı maddesi yok), pozitif kontrol (5 mg/gün monensin) ve U. dioica (500 mg/gün), M. chamomilla (500 mg/gün) ve V. agnus-castus (500 mg/gün) ekstraktlarından oluşmuştur. Bitki ekstraktları ve monensin ruminal pH’yi normal koşullar ve asidoz koşulları altında değiştirmemiştir. Deneme gruplarının toplam uçucu yağ asidi (UYA) ve propiyonat üretimi ile kuru madde sindirilebilirliği (KMS) üzerine etkilerinin koşuldan bağımsız olarak gerçekleştiği gözlenmiştir. Üç ekstrakt da monensin’e benzer şekilde toplam UYA üretimini arttırmıştır (P, The aim of this study wasto investigate the effects of dry extracts ofUrtica dioica, Matricaria chamomilla, and Vitex agnus-castuswith high phenolic contents on rumen microbial fermentation as compared with thoseof monensin, a common ionophoreantibiotic, using Rumen Simulation Technique (RUSITEC) under normal andacidosis conditions. The treatments were as follows: negative control (noadditive), positive control (5 mg/d monensin), and extracts of U. dioica (500mg/d), M. chamomilla (500 mg/d), and V. agnus-castus (500 mg/d). Neitherthe plant extracts nor monensin altered the ruminal pH under normal or acidosisconditions. All the treatments affected total volatile fatty acid (VFA) production,propionate production, and dry matter digestibility (DMD), regardless of the fermentation conditions.All threeextracts increased (P

During the transition period, dairy cows suffer from negative energy balance due to the upcoming insulin resistance as a major metabolic disturbance. We hypothesized that providing glucose precursors for transition dairy cows may reduce the insulin resistance. In this study, 24 multiparous Holstein dairy cows were enrolled 8 weeks prior to parturition and divided into 4 equal groups, including control (Ctrl), monensin (Mo), propylene glycol (PPG), and monensin plus propylene glycol (Mo + PPG). Cows from the Mo and PPG groups received 1 mg/kg body weight (BW) of monensin, daily. Cows from the PGG group received 150 g of propylene glycol, daily. Cows from the Mo + PPG group received 1 mg/kg BW of monensin and 150 g/head of propylene glycol daily and Ctrl cows received basal diet without any supplementations. Intravenous glucose tolerance test (ivGTT) was conducted weekly from 3 weeks before to 3 weeks after parturition to evaluate the insulin resistance phenomenon. Immediately after glucose administration, glucose and insulin increased significantly, and their alterations were significant during the study. Glucose and insulin were significantly higher in the Ctrl group than in the other groups, and their levels in different pre- and post-partum periods were significantly lower in the Mo + PPG group than in the other studied groups. The results of this study represented that the supplementary feeding with propionate precursors, such as monensin and propylene glycol, reduced the insulin resistance in dairy cows during the transition period. This effect is more explicit by propylene glycol than by monensin, and the combination of both reduces insulin resistance at higher rates. The use of these dietary supplements is likely to produce more propionates as the main precursor of glucose; therefore, it reduces the negative energy balance and subsequently decreases the insulin resistance. In this regard, to reduce insulin resistance, it is recommended that dairy cows during the transition period be fed with monensin and propylene glycol supplements.

This study was designed to assess the effects of Moringa oleifera (moringa) leaf ethanolic extract (MLEE), moringa root ethanolic extract (MREE), and ionophore antibiotic monensin on growth performance, hematological variables, blood plasma metabolites and antioxidant indicators, digestibility, and cecal fermentation of growing rabbits. A total of 96 growing rabbits weaned at 35 d of age were randomly assigned to 4 treatments with 12 male and 12 female rabbits/treatment. The first treatment was the control (no additives), the second treatment was a basal diet containing 10 mg monensin/kg dry matter (DM), and the third and fourth treatments were MLEE and MREE, respectively, at concentration of 250 mg/L drinking water. From 35 to 77 d of age, the rabbits were housed in groups (8 cages/treatment, 3 rabbits/cage), and growth performance variables including body weight (BW), feed consumption, BW gain, and feed conversion ratio were recorded. From 78 to 93 d of age, after the end of the growth performance trial, the rabbits were housed individually. At 87 d of age, blood samples were collected from 10 rabbits (5 males and 5 females) that were selected randomly to determine hematological variables and blood plasma metabolites and antioxidant indicators. From 87 to 93 d of age, 8 male rabbits/treatment were selected randomly to determine digestibility, N balance, and cecal fermentation activity. The major chemical compounds in MLEE were α-linolenic acid, glycerine, ascorbic acid, and diethyl phthalate, whereas ascorbic acid, S-phenylmercapturic acid, 2-myristynoyl pantetheine, and 8,11,14-docosatrienoic acid, methyl ester were major compounds in MREE. Both the MLEE and MREE treatments improved (P

The objectives of this study were to assess the effects of Saccharomyces cerevisiae fermentation products (SCFP; NaturSafe, SCFPns; and Original XPC, XPC; Diamond V) on growth performance, carcass traits, immune response, and antimicrobial resistance in beef steers fed high-grain diets. Ninety Angus steers (initial body weight [BW], 533 ± 9.8 kg) were assigned to a randomized complete design with 6 treatments (n = 15/treatment): 1) control, 2) low (12 g SCFPns·steer−1·d−1), 3) medium (15 g SCFPns·steer−1·d−1), 4) high SCFP (18 g SCFPns·steer−1·d−1), 5) encapsulated XPC (eXPC; 7 g XPC·steer−1·d−1 encapsulated with 9 g capsule material), and 6) antibiotics (ANT; 330 mg monensin + 110 mg tylosin·steer−1·d−1). Steers were fed ad libitum a diet containing 10% barley silage and 90% barley grain concentrate mix (dry matter basis) for 105 d. Increasing SCFPns tended (P < 0.09) to linearly increase feed efficiency. Average daily gain (ADG) tended (P < 0.10) to be greater in steers supplemented with eXPC than control. The SCFPns also tended (P < 0.10) to linearly increase marbling score. Proportion of severely abscessed livers tended (P < 0.10) to be lower in steers supplemented with medium and high SCFPns, eXPC, or ANT. A treatment × days on feed interaction were noticed (P < 0.01) for blood glucose, blood urea nitrogen (BUN), and acute phase proteins. The concentration of blood glucose responded quadratically (P < 0.05) on days 28 and 56, whereas BUN linearly (P < 0.01) increased on day 105 with increasing SCFPns dose. The SCFPns linearly increased haptoglobin (P < 0.03) and serum amyloid A (SAA;P < 0.05) concentrations on day 105, and lipopolysaccharide binding protein (LBP;P < 0.01) on days 56 and 105. The percentage of erythromycin-resistant and erythromycin + tetracycline-resistant enterococci was greater (P < 0.05) with ANT than control, SCFPns, and eXPC, whereas no difference was observed among control, SCFPns, and eXPC. No treatment effect was detected on the percentage of tetracycline-resistant enterococci. These results indicate that feeding SCFPns and eXPC was beneficial in improving ADG, feed efficiency and decreasing liver abscesses in a manner comparable to ANT. Unlike antibiotics, SCFPns or eXPC did not increase antimicrobial resistance. Both SCFPns and eXPC are potential alternatives to in-feed antibiotics.

The current study evaluated growth performance and digestion responses of finishing bulls fed diets containing 825 g/kg flint maize [dry matter (DM) basis] ground to medium (1.66 mm; MG) or coarse particle sizes (2.12 mm; CG), with added monensin (26 mg/kg; DM basis; MON) or a blend of essential oils (BEO) + exogenousα-amylase (AM; 90 mg/kg + 560 mg/kg commercial product, respectively, DM basis). In Expt 1, 256 Nellore bulls were blocked by initial body weight (BW) (360 ± 11.7 kg) and assigned to 48 pens in a 2 × 2 factorial arrangement of treatments. Effect of a maize particle size × feed additive interaction was not detected for final BW, DM intake (DMI), average daily gain (ADG) and feed efficiency. The DMI was greater for bulls fed BEO + AMv.MON. Final BW and ADG tended to be greater for bulls fed CG than MG maize. An interaction was detected for hot carcass weight which was 11 kg heavier for bulls fed BEO + AMv.MON in diets containing CG, but not MG particle size. In Expt 2, four ruminally cannulated Nellore steers were offered the same treatments as Expt 1, in a 4 × 4 Latin Square design. Intake of most nutrients was greater for steers fed CG than steers fed MG maize. In summary, feeding bulls CG maize increased growth performance and carcass characteristics compared with MG. The combination of BEO + AM resulted in heavier carcass weights compared with MON supplementation when included in diets containing CG maize.

It is commonplace that metabolizable energy (ME) is calculated from digestible energy (DE) as DE × 0.82. However, recent published literature suggests that the relationship between DE and ME is variable depending on the type of diet used, and is typically > 0.90 when high-concentrate diets are fed. Literature means were compiled from 23 respiration calorimetry studies where total fecal and urine collections were conducted and gaseous energy was measured. The relationship between experimentally observed and predicted ME (DE × 0.82) was evaluated using these previously reported treatment means. Additionally, a previously published linear regression equation for predicting ME from DE was also evaluated using a residual analysis. Published (Hales, K. E., A. P. Foote, T. M. Brown-Brandl, and H. C. Freetly. 2017. The effects of feeding increasing concentrations of corn oil on energy metabolism and nutrient balance in finishing beef steers. J. Anim. Sci. 95:939–948. doi:10.2527/jas.2016.0902 and Hemphill, C. N., T. A. Wickersham, J. E. Sawyer, T. M. Brown-Brandl, H. C. Freetly, and K. E. Hales. 2018. Effects of feeding monensin to bred heifers fed in a drylot on nutrient and energy balance. J. Anim. Sci. 96:1171–1180. doi:10.1093/jas/skx030) and unpublished data (K. E. Hales, unpublished data) were used to develop a new equation for estimating ME from DE (megacalories/kilogram [Mcal/kg] of DM; ME = −0.057 ± 0.022 DE2 + 1.3764 ± 0.1197 DE – 0.9483 ± 0.1605; r2 = 0.9671, root mean square error = 0.12; P < 0.01 for intercept, P < 0.01 for linear term, and P < 0.01 for quadratic term). To establish a maximum biological threshold for the conversion of DE to ME, individual animal data were used (n = 234) to regress the ME:DE on DE concentration (1.53 to 3.79 Mcal DE/kg). When using experimentally derived data and solving for the first derivative, the maximum biological threshold for the conversion of DE to ME was 3.65 Mcal DE/kg. Additionally, the quadratic regression (equation 1) was used to predict ME from a wide range of DE (1.8 to 4.6 Mcal/kg). The ME:DE ratio was then calculated by dividing predicted ME by DE. The maximum biological threshold for the conversion of DE to ME was estimated by solving for the first derivative and was 3.96 Mcal DE/kg. In conclusion, this review suggests that the relationship between DE and ME is not static, especially in high-concentrate diets. The equation presented here is an alternative that can be used for the calculation of ME from DE in current feedlot diets, but it is not recommended for use in high-forage diets. The maximization of ME in current diets, maximum biological threshold, occurs between 3.65 and 3.96 Mcal DE/kg in the diet, which based on these data is approximately 3.43 to 3.65 Mcal/kg of ME consumption.

Objective A microencapsulated blend of essential oils (EO) fed to feedlot cattle was evaluated against monensin (MON) or used in association with MON and compared against MON alone or MON + tylosin (TYL). Materials and Methods We used a randomized complete block design using weaned steers (n = 656; 254.4 ± 7.9 kg of initial BW) assigned to 32 pens (8 replicates per treatment) and fed for 208 d. The treatments were as follows: MON + TYL (33 mg and 11 mg/kg of DM, respectively); MON (33 mg/kg of DM); EO (150 mg/kg of DM); and MON + EO (33 mg and 150 mg/kg of DM, respectively). Results and Discussion Treatments were similar for final BW (P ≥ 0.24) and overall ADG (P ≥ 0.27). Overall DMI did not differ for MON versus EO (P ≥ 0.93); however, MON + EO had reduced overall DMI compared with MON (P = 0.03; 9.2 vs. 9.6 kg/d, respectively) or MON + TYL (P = 0.04; 9.2 vs. 9.6 kg/d, respectively). There was no effect (P ≥ 0.14) on overall G:F; however, adjusted overall G:F tended to be greater for MON + EO versus MON (P = 0.08; 0.187 vs. 0.182, respectively) and for MON + EO versus MON + TYL (P = 0.07; 0.187 vs. 0.183, respectively). Carcass characteristics were similar (P ≥ 0.11) for all treatments. Implications and Applications Steers receiving EO had similar performance and carcass characteristics compared with steers fed MON. The MON + EO tended to improve carcass-adjusted performance compared with MON. The replacement of TYL with EO when in combination with MON may result in additional improvement in feed efficiency without changes in liver abscesses.

Stocker operators generally graze cattle on California annual rangelands from November to May. The profit margins of these operators is low as cattle sell for less per unit at the end of the season when compared with the beginning. This creates a need for methods to economically increase weight gain, which can help to mitigate market volatility. The use of monensin is common in much of the United States but has not been researched in the unique winter annual rangelands of California. Likewise, research that formally documents weight gain from the correction of selenium deficiency on these rangelands is also lacking. Trials were conducted over 2 years to determine weight gain differences with treatments of salt only (control), salt with monensin, mineral supplement, and mineral supplement with monensin. All three treatments increased weight gain by 12%, 9%, and 15% over feeding straight salt, respectively. It appears that selenium deficiency correction and supplemental monensin should be considered economical weight gain improvement tools for yearling cattle grazing California annual rangeland.

Simple Summary The use of a controlled-release capsule of monensin for the prevention of ketosis in dairy cows, nowadays, has become widespread. In Europe, this is the only use of monensin permitted in dairy cows. Literature regarding the use of this molecule as a feed additive or controlled-release capsule is extensive, and results reported across studies vary with respect to the mode and dose of administration, target animals, and period of lactation. Therefore, the aim of this review was to summarize the literature observations regarding the use of monensin for the prevention of ketosis in dairy cows during the transition period. Abstract Since the approval by the European Medicines Agency in 2013 of a monensin controlled-release capsule (CRC) for the prevention of ketosis in dairy cows, there has been widespread use across Europe. In recent decades, several papers have investigated the effects of monensin used as a CRC or as a feed additive to improve cattle energy metabolism and improve feed efficiency. Since the CRC is the only form of monensin permitted in Europe in dairy cows, the objective of this review was to report and summarize observations from the literature on the effects of this treatment in transition cows. The peer-reviewed literature published from 1997 was scanned, and papers written in English were evaluated for eligibility. Only papers evaluating the use of monensin in dairy cows for the prevention of ketosis during the transition period were reviewed. In total, 42 papers met the required criteria and were included in this review. The major findings focused on cow metabolism and health, rumen fermentation and milk production and quality. Overall, the review of the existing literature confirmed that monensin delivered as a CRC during the transition period has effects of different magnitude compared to other forms, doses or durations of administration. Studies agree on the antiketotic effects of this treatment, showing evidence of an increased propionate production in the rumen, reduced blood β-hydroxybutyrate, and improved liver function in treated cows, mainly resulting in reduced incidence of peripartum disease. On the contrary, the effects of CRC on ammonia production and rumen microflora are less robust than those reported for other forms. Of importance for the European market is the well-documented absence of any negative impact on milk and cheese production and composition using the CRC treatment.

Two experiments were conducted to evaluate the effects of feed additives [monensin (MON); 30 mg/kg of dry matter (DM), and virginiamycin (VM); 25 mg/kg DM] and grain adaptation programs [adding roughage (ROU; sugarcane bagasse) or not (NO-ROU) during the 20-d adaptation period] on performance, carcass characteristics, and nutrient digestibility of Bos indicus cattle fed finishing diets containing 85% whole shelled corn and 15% of a pelleted protein-mineral-vitamin supplement. In Exp.1, 105 Nellore bulls [initial body weight (BW) = 368 ± 25 kg] were used in a complete randomized block design with a 2 × 2 factorial arrangement of treatments, consisting of two feed additives (MON and VM) associated with two adaptation programs (ROU or NO-ROU during the 20-d adaptation period). Effects of feed additives × adaptation programs were not detected (P ≥ 0.13). Feed additives did not affect dry matter intake (DMI), average daily gain (ADG), and feed efficiency (G:F) during the 20-d adaptation period (P ≥ 0.35). During the total feeding period (105 d), feeding MON decreased DMI (P ≤ 0.03) compared to VM. Adding sugarcane bagasse to finishing diets during the 20-d adaptation period (ROU) increased ADG (P = 0.05) and G:F (P = 0.03), and tended to increase BW (P = 0.09) compared to NO-ROU. In Exp. 2, 10 ruminally cannulated Nellore steers (BW = 268 ± 38 kg) were used in a completely randomized design to evaluate the effects of the two feed additives used in the Exp. 1 (MON and VM; 5 steers/treatment) on DMI, total apparent digestibility of nutrients, and ruminal fermentation characteristics. No differences in DMI, total tract apparent digestibility of nutrients, and ruminal fermentation characteristics were observed between MON and VM (P ≥ 0.32). An effect of sampling day (P < 0.001) was observed for ruminal pH, which was greater on day 0 compared to day 7, 14, and 21 of the experimental period (P ≤ 0.05). In summary, supplementing monensin and virginiamycin for finishing Nellore bulls fed whole shelled corn diets, resulted in similar growth performance and carcass characteristics. Including sugarcane bagasse to adapt finishing bulls to no-roughage diets containing whole shelled corn is an alternative to increase growth performance.

Lubabegron (LUB; Experior, Elanco, Greenfield, IN, USA) was approved by the U.S. Food and Drug Administration in 2018 and is indicated for the reduction of ammonia (NH3) gas emissions·kg−1 body weight (BW) and hot carcass weight (HCW) when fed to feedlot cattle during the final 14 to 91 d of the finishing period. LUB demonstrates antagonistic behavior at the β 1 and β 2 receptor subtypes and agonistic behavior at the β 3 receptor subtype in cattle and is classified by the Center for Veterinary Medicine as a “beta-adrenergic agonist/antagonist.” This report describes a randomized complete block study that evaluated LUB dose (0, 1.5, 3.5, and 5.5 mg·kg−1 dry matter) during the last 56 d of the feeding period on calculated NH3 gas emissions, live weight, carcass weight, and associated ratios in beef feedlot cattle. Carcass characteristics, mobility, and health were also evaluated. All cattle received monensin and tylosin throughout the study. Ammonia gas emissions were calculated using the equation developed by Brown et al. (Brown, M. S., N. A. Cole, S. Gruber, J. Kube, and J. S. Teeter. 2019. Modeling and prediction accuracy of ammonia gas emissions from feedlot cattle. App. Anim. Sci. 35:347–356). The reduction in calculated cumulative NH3 gas emissions with LUB ranged from 1.3% to 11.0% (85 to 708 g/hd). When NH3 gas emissions were expressed on a live weight (unshrunk) and carcass weight basis, calculated NH3 gas emissions decreased by 3.0% to 12.8% and 3.8% to 14.6%, respectively. Daily dry matter intake was 2.3% greater (Ptrt < 0.05) for steers that received LUB. Average daily gain was 13.7% greater (Ptrt < 0.05; 1.68 vs. 1.91 kg), while gain efficiency was 10.8% greater (Ptrt < 0.05; 0.167 vs. 0.185) for steers fed LUB. Animal mobility was scored in the pen approximately 1 wk prior to harvest, when cattle were loaded on trucks scheduled for harvest, and at antemortem inspection during lairage. No treatment differences (Ptrt ≥ 0.170) were observed at any time for the percent of cattle receiving mobility scores of 1 or 2 (normal or minor stiffness but moving with the normal cattle, respectively). Cattle mobility scored as a 1 or 2 equaled or exceeded 92% at all times. Final BW and HCW increased (Ptrt < 0.05) 11.6 to 15.7 kg and 11.3 to 17.1 kg, respectively, in cattle receiving LUB compared to cattle receiving monensin plus tylosin alone.

This study evaluated the growth, physiology, and coccidiosis infestation of suckling beef calves provided monensin and grazing limpograss (Exp. 1) or bahiagrass (Exp. 2) pastures. Treatments were randomly assigned to pastures (4 pastures/treatment; 3 cow-calf pairs/pasture in Exp. 1; 4 pastures/treatment; 10 cow-calf pairs/pair of pastures in Exp. 2) and comprised of supplementation of 0.40 kg/d of soybean meal added or not with monensin (20 mg/kg of total DM intake) for 112 and 78 days before weaning in Exp. 1 and 2, respectively. In Exp. 1, supplement DM disappearance tended (P = 0.10) to be less for calves supplemented with vs. without monensin, but treatment × day and treatment effects were not observed (P ≥ 0.18) for herbage mass (HM), herbage allowance (HA), cow body condition score (BCS), calf average daily gain (ADG), calf plasma data, and fecal coccidia egg count. In Exp. 2, forage nutritive value, HM and HA, and cow BCS did not differ (P ≥ 0.43) between treatments. Supplemental monensin did not impact (P ≥ 0.78) plasma concentrations of insulin-like growth factor 1 but increased (P ≤ 0.05) calf overall ADG and plasma concentrations on day 78 and reduced plasma concentrations of urea nitrogen (PUN) on day 78 and fecal coccidia egg count on day 78 compared to calves provided no monensin supplementation. Hence, monensin supplementation successfully improved growth performance of creep-fed suckling beef calves, when herbage mass was not a limiting factor and coccidiosis infestation occurred.

Made available in DSpace on 2021-06-25T10:26:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Additives used to improve feed efficiency of beef cattle on high-grain diets requires products that not only increase animal performance but also provide food safety for consumers. Since phytogenic additives such as essential oils (EO) are the main substitutes for monensin in the diet of cattle fed high-grain diets, this study aimed to evaluate, through meta-analysis, the effects of EO as an alternative to monensin in diets for beef cattle on feed intake, performance, carcass characteristics and ruminal fermentative parameters. Ten peer-reviewed publications with 27 treatment means were included in the data set. These effects were evaluated using random-effect models to examine the weighted mean differences (WMD) between EO treatment and control treatment (diets with monensin). Heterogeneity was explored by meta-regression and subgroup analysis. The substitution of EO for monensin did not affect methane production, ruminal pH values, average daily gain, feed efficiency or carcass weight. However, carcass dressing percentage (WMD = 0.38%; P = 0.03), ribeye area (WMD = 0.82 cm2; P < 0.0001) and subcutaneous fat thickness (WMD = 0.56 mm; P < 0.0001) values increased. Although the use of EO instead of monensin had no influence on the performance of beef cattle fed high-grain diets, the prevalence of hepatic abscesses increased 84.9% and the replacement of monensin by EO increased the risk ratio of hepatic abscess prevalence by 107%. Therefore, the use of EO in high-grain beef cattle diets was ineffective in protecting the liver against abscesses. Animal Unit of Digestive and Metabolic Studies Department of Animal Science School of Agricultural and Veterinary Sciences São Paulo State University (UNESP) Federal University of Piauí Department of Biological Safety German Federal Institute for Risk Assessment Federal University of Espírito Santo Department of Animal Science Animal Unit of Digestive and Metabolic Studies Department of Animal Science School of Agricultural and Veterinary Sciences São Paulo State University (UNESP)

Nutritional strategies that optimize immunity of feedlot cattle are warranted due to increasing regulations with the use of feed-grade antimicrobials. This study evaluated physiological, health, and performance responses of cattle receiving a synbiotic supplement (yeast-derived prebiotic + Bacillus subtilis probiotic), which replaced feed-grade antimicrobials or were fed in conjunction with monensin during the initial 45 days in the feedlot. Angus-influenced steers (n = 256) were acquired from an auction facility on day −2, and transported (800 km) to the feedlot. Shrunk BW was recorded upon arrival (day −1). Steers were allocated to 1 of 18 pens (day 0), and pens were assigned to receive (n = 6/treatment) a free-choice diet containing: (1) monensin and tylosin (RT; 360 mg/steer daily from Rumensin and 90 mg/steer daily from Tylan; Elanco Animal Health, Greenfield, IN, USA), (2) yeast-derived ingredient and B. subtilis probiotic (CC; 18 g/steer daily of Celmanax and 28 g/steer daily of Certillus; Church and Dwight Co., Inc., Princeton, NJ, USA), or (3) monensin in addition to yeast-derived and B. subtilis ingredients (RCC) as in RT and CC. Steers were assessed for bovine respiratory disease (BRD) and DMI daily. Steer BW was recorded on days 45 and 46, and averaged for final BW. Blood samples were collected on days 0, 7, 17, 31, and 45. Feed intake was greater (P ≤ 0.05) in CC vs. RCC and RT during the initial 3 weeks upon feedlot arrival. No treatment differences were noted (P ≥ 0.41) for average daily gain, BW, and feed efficiency. Incidence of BRD did not differ (P = 0.77) between treatments (average 80.1%). A greater proportion (P ≤ 0.03) of RT steers diagnosed with BRD required a second antimicrobial treatment compared with CC and RCC (57.3, 37.3, and 38.6%, respectively). Removal of steers from the trial due to severe morbidity + mortality was greater (P = 0.02) in RT vs. CC (22.4 and 7.0%), and did not differ (P ≥ 0.16) among RCC (12.9%) vs. RT and CC. Plasma glucose concentrations were greater (P ≤ 0.02) in CC vs. RCC and RT on day 7. Plasma concentrations of nonesterified fatty acids were greater (P ≤ 0.02) in RT and RCC vs. CC on day 7, and in RT vs. CC on day 17. Steers receiving the synbiotic supplement had improved response to BRD treatment, suggesting heightened immunocompetence from partially enhanced metabolism and the nutraceutical effects of B. subtilis and yeast compounds.

A 2-yr grazing experiment was conducted to evaluate efficacy of nitrogen (N) fertilization, interseeded legumes, and protein supplementation for N delivery to stocker cattle grazing annual ryegrass (Lolium multiflorum). Each year, 90 steers (initial BW, 241 ± 13 kg) were assigned to the following N-delivery methods, with or without monensin fed in a free-choice mineral supplement as a 5 × 2 factorial arrangement of treatments: ryegrass fertilized with 112 kg N/ha (NFERT); ryegrass interseeded with crimson clover (CC, Trifolium incarnatum); ryegrass interseeded with arrowleaf clover (AC, Trifolium vesiculosum); ryegrass plus distillers dried grains with solubles (DDGS) supplemented at 0.65% BW daily; and ryegrass plus whole cottonseed (WCS) supplemented at 0.65% BW daily. Pastures within the interseeded-clover and protein-supplementation treatments were fertilized with 56 kg N/ha at time of establishment. Steers were weighed every 28 d, and forage mass (FM, kg DM/ha) was measured concurrently using the destructive harvest/disk meter double-sampling method. Each of 30 0.81-ha paddocks was stocked initially with 3 “tester” steers, and stocking density (steers/ha) was adjusted using “put-and-take steers” based on changes in FM and steer BW in order to maintain a uniform forage allowance (FA) of 1 kg DM/kg steer BW. Grazing was discontinued on May 11, 2016 in Yr 1 and May 10, 2017 in Yr 2 following 140 and 84 d of grazing, respectively. Data were analyzed as a completely randomized design with repeated measures for which pasture (n = 3) was the experimental unit. Ionophore inclusion did not affect (P > 0.10) any variable measured. Mean FM differed (P < 0.0001) between years and among N-delivery methods (P < 0.10), and mean FA differed (P = 0.005) among N-delivery methods. Steer ADG differed among N-delivery methods (P = 0.02) and between years (P < 0.001), whereas total gain/ha differed (P < 0.0008) among N-delivery methods, but not between years (P = 0.78). Stocking density differed among N-delivery methods (P = 0.02) and between years (P < 0.0001), and grazing-days/ha differed between years (P < 0.0001) and among N-delivery methods (P = 0.001). Results indicate that supplementation with a high-protein by-product feed for cattle grazing annual ryegrass maintained ADG, total gain/ha and grazing-days/ha compared with N-fertilized annual ryegrass, and increased ADG, total gain/ha, and grazing-days over interseeded legumes.