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Nutritional alternatives to strengthen animal immunocompetence are critical for welfare and productivity in livestock systems, such as beef cattle operations. This experiment evaluated physiological and innate immunity effects of supplementing an immunomodulatory feed ingredient (Omnigen-AF; Phibro Animal Health, Teaneck, NJ, USA) to beef heifers administered bacterial lipopolysaccharide (LPS). In total, 8 non-pregnant, non-lactating nulliparous Angus×Hereford heifers (676±4 days of age) were ranked by BW (473±8 kg), and assigned to crossover design containing two periods of 34 days each. Heifers were housed in individual pens and had ad libitum access to meadow foxtail (Alopecurus pratensis L.) hay, water and a granulated commercial vitamin+mineral mix. Within each period, heifers received (as-fed basis) 227 g/day of dried distillers grains including (OMN) or not (CON) 56 g of Omnigen-AF for 34 days. On day 28 of each period (0800 h), heifers received an intravenous bolus dose (0.5 μg/kg of BW, diluted in 5 ml of 0.9% sterile saline) of bacterial LPS (Escherichia coli 0111:B4). Hay DM intake was recorded daily from day 0 to 34. Blood was collected at −1, 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 24, 48, 72, 96, 120 and 144 h relative to LPS administration. Heifer intravaginal temperature was recorded every 10 min from −0.5 to 10 h relative to LPS administration. No treatment effect was detected (P =0.35) for hay DM intake during the experiment. No treatment effects were detected (P ⩾0.64) for intravaginal temperature and plasma concentrations of tumor necrosis- α , cortisol and haptoglobin, which increased (time effect, P <0.01) for OMN and CON heifers and peaked at 4.5, 2, 4 and 48 h, respectively, after LPS administration. No treatment effects were detected (P ⩾0.35) for whole blood mRNA expression of chemokine ligand 5 , tumor necrosis-α , cyclooxygenase 2 and interleukin 8 , which also increased (time effect, P <0.01) for OMN and CON heifers and peaked at 0.5, 1.5, 2 and 2.5 h, respectively, after LPS administration. Whole blood mRNA expression of interleukin 8 receptor and L-selectin were also similar (P ⩾0.61) between OMN and CON heifers, and decreased (time effect, P <0.01) for both treatments reaching nadir levels at 1 and 2.5 h, respectively, after LPS administration. Collectively, OMN supplementation did not modulate the physiological and innate immunity responses of beef heifers to bacterial LPS administration. [ABSTRACT FROM AUTHOR]

With increased regulations regarding the use of feed-grade antimicrobials in livestock systems, alternative strategies to enhance growth and immunity of feedlot cattle are warranted. Hence, this experiment compared performance, health and physiological responses of cattle supplemented with feed-grade antibiotics or alternative feed ingredients during the initial 60 days in the feedlot. Angus×Hereford calves (63 steers+42 heifers) originating from two cow–calf ranches were weaned on day −3, obtained from an auction yard on day −2 and road-transported (800 km; 12 h) to the feedlot. Upon arrival on day −1, shrunk BW was recorded. On day 0, calves were ranked by sex, source and shrunk BW, and allocated to one of 21 pens. Pens were assigned to receive (7 pens/treatment) a free-choice total mixed ration containing: (1) lasalocid (360 mg/calf daily of Bovatec; Zoetis, Florham Park, NJ, USA)+chlortetracycline (350 mg/calf of Aureomycin at cycles of 5-day inclusion and 2-day removal from diet; Zoetis) from days 0 to 32, and monensin only (360 mg/calf daily of Rumensin; Elanco Animal Health, Greenfield, IN, USA) from days 33 to 60 (PC), (2) sodium saccharin-based sweetener (Sucram at 0.04 g/kg of diet dry matter; Pancosma SA; Geneva, Switzerland)+plant extracts containing eugenol, cinnamaldehyde and capsicum (800 mg/calf daily of XTRACT Ruminants 7065; Pancosma SA) from days 0 to 32 and XTRACT only (800 mg/calf daily) from days 33 to 60 (EG) or (3) no supplemental ingredients (CON; days 0 to 60). Calves were assessed for bovine respiratory disease (BRD) signs and dry matter intake was recorded from each pen daily. Calves were vaccinated against BRD pathogens on days 0 and 22. Shrunk BW was recorded on day 61, and blood samples collected on days 0, 6, 11, 22, 33, 43 and 60. Calf ADG was greater (P =0.04) in PC v. EG and tended (P =0.09) to be greater in PC v. CON. Feed efficiency also tended (P =0.09) to be greater in PC v. CON, although main treatment effect for this response was not significant (P =0.23). Mean serum titers against bovine respiratory syncytial virus were greater in EG v. PC (P =0.04) and CON (tendency; P =0.08). Collectively, the inclusion of alternative feed ingredients prevented the decrease in feed efficiency when chlortetracycline and ionophores were not added to the initial feedlot diet, and improved antibody response to vaccination against the bovine respiratory syncytial virus in newly weaned cattle. [ABSTRACT FROM AUTHOR]

This experiment evaluated the impacts of supplementing a yeast-derived product (Celmanax; Church & Dwight Co., Inc., Princeton, NJ, USA) on productive and health responses of beef steers, and was divided into a preconditioning (days 4 to 30) and feedlot receiving phase (days 31 to 69). In all, 84 Angus × Hereford steers were weaned on day 0 (BW=245±2 kg; age=186±2 days), and maintained in a single group from days 0 to 3. On day 4, steers were allocated according to weaning BW and age to a 21-pen drylot (4 steers/pen). Pens were randomly assigned to ( n =7 pens/treatment): (1) no Celmanax supplementation during the study, (2) Celmanax supplementation (14 g/steer daily; as-fed) from days 14 to 69 or (3) Celmanax supplementation (14 g/steer daily; as-fed) from days 31 to 69. Steers had free-choice access to grass-alfalfa hay, and were also offered a corn-based concentrate beginning on day 14. Celmanax was mixed daily with the concentrate. On day 30, steers were road-transported for 1500 km (24 h). On day 31, steers returned to their original pens for the 38-day feedlot receiving. Shrunk BW was recorded on days 4, 31 and 70. Feed intake was evaluated daily (days 14 to 69). Steers were observed daily (days 4 to 69) for bovine respiratory disease (BRD) signs. Blood samples were collected on days 14, 30, 31, 33, 35, 40, 45, 54 and 69, and analyzed for plasma cortisol, haptoglobin, IGF-I, and serum fatty acids. Preconditioning results were analyzed by comparing pens that received (CELM) or not (CONPC) Celmanax during the preconditioning phase. Feedlot receiving results were analyzed by comparing pens that received Celmanax from days 14 to 69 (CELPREC), days 31 to 69 (CELRECV) or no Celmanax supplementation (CON). During preconditioning, BRD incidence was less ( P =0.03) in CELM v. CONPC. During feedlot receiving, average daily gain (ADG) ( P =0.07) and feed efficiency ( P =0.08) tended to be greater in CELPREC and CELRECV v. CON, whereas dry matter intake was similar ( P ⩾0.29) among treatments. No other treatment effects were detected ( P ⩾0.20). Collectively, Celmanax supplementation reduced BRD incidence during the 30-day preconditioning. Moreover, supplementing Celmanax tended to improve ADG and feed efficiency during the 38-day feedlot receiving, independently of whether supplementation began during preconditioning or after feedlot entry. These results suggest that Celmanax supplementation benefits preconditioning health and feedlot receiving performance in beef cattle. [ABSTRACT FROM AUTHOR]

In all, 60 Angus×Hereford heifers were ranked by age and BW (210±2 days and 220±2 kg) on day 0, and assigned to: (a) one of three drylot pens (10×14 m pens; 10 heifers/pen) resulting in a stocking density of 14 m2/heifer (HIDENS; n=3), or (b) one of three pastures (25 ha pastures; 10 heifers/pasture), resulting in a stocking density of 25 000 m2/heifer (LOWDENS; n=3). Pastures were harvested for hay before the beginning of this experiment, and negligible forage was available for grazing to LOWDENS heifers during the experiment (days 0 to 182). All heifers received the same limited-fed diet, which averaged (dry matter basis) 4.0 kg/heifer daily of hay and 3.0 kg/heifer daily of a corn-based concentrate. Heifer shrunk BW was recorded after 16 h of feed and water withdrawal on days −3 and 183 for BW gain calculation. On day 0, heifers were fitted with a pedometer behind their right shoulder. Each week, pedometer results were recorded and blood samples were collected for puberty evaluation via plasma progesterone. Plasma samples collected on days 0, 28, 56, 84, 112, 140, 161 and 182 were also analyzed for cortisol concentrations. On days 0, 49, 98, 147 and 182, hair samples were collected from the tail switch for analysis of hair cortisol concentrations. On days 28, 102 and 175, blood samples were collected for whole blood RNA isolation and analysis of heat shock protein (HSP) 70 and HSP72 mRNA expression. Heifers from LOWDENS had more (P<0.01) steps/week compared with HIDENS. No treatment effects were detected (P=0.82) for heifer BW gain. Plasma cortisol concentrations were greater (P⩽0.05) in LOWDENS compared with HIDENS heifers on days 84, 140, 161 and 182 (treatment×day interaction; P<0.01). Hair cortisol concentrations were greater (P<0.01) in HIDENS compared with LOWDENS heifers beginning on day 98 (treatment×day interaction; P<0.01). Heifers from LOWDENS had greater (P=0.04) mean mRNA expression of HSP72, and tended (P=0.09) to have greater mean mRNA expression of HSP70 compared with HIDENS. Heifers from HIDENS experienced delayed puberty attainment and had less (P<0.01) proportion of pubertal heifers on day 182 compared with LOWDENS (treatment×day interaction; P<0.01). In summary, HIDENS altered heifer stress-related and physiological responses, and delayed puberty attainment compared with LOWDENS. [ABSTRACT FROM PUBLISHER]

This experiment evaluated production and health parameters among cattle offered concentrates containing inorganic or organic complexed sources of supplemental Cu, Co, Mn and Zn during a 45-day preconditioning period. In total, 90 Angus×Hereford calves were weaned at 7 months (day −1), sorted by sex, weaning BW and age (261±2 kg; 224±2 days), and allocated to 18 drylot pens (one heifer and four steers per pen) on day 0; thus, all pens had equivalent initial BW and age. Pens were randomly assigned to receive a corn-based preconditioning concentrate containing: (1) Cu, Co, Mn and Zn sulfate sources (INR), (2) Cu, Mn, Co and Zn complexed organic source (AAC) or (3) no Cu, Co, Mn and Zn supplementation (CON). From day 0 to 45, cattle received concentrate treatments (2.7 kg/animal daily, as-fed basis) and had free-choice access to orchardgrass (Dactylis glomerata L.), long-stem hay and water. The INR and AAC treatments were formulated to provide the same daily amount of Co, Cu, Mn and Zn at a 50-, 16-, 8- and ninefold increase, respectively, compared with the CON treatment. On day 46, cattle were transported to a commercial feedlot, maintained as a single pen, and offered a free-choice receiving diet until day 103. Calf full BW was recorded on days −1 and 0, 45 and 46, and 102 and 103 for average daily gain (ADG) calculation. Liver biopsy was performed on days 0 (used as covariate), 22 and 45. Cattle were vaccinated against respiratory pathogens on days 15, 29 and 46. Blood samples were collected on days 15, 29, 45, 47, 49, 53 and 60. During preconditioning, mean liver concentrations of Co, Zn and Cu were greater (P⩽0.03) in AAC and INR compared with CON. No treatment effects were detected (P⩾0.17) for preconditioning feed intake, ADG or feed efficiency. No treatment effects were detected (P⩾0.48) for plasma concentrations of antibodies against Mannheimia haemolytica, bovine viral diarrhea types 1 and 2 viruses. Plasma haptoglobin concentrations were similar among treatments (P=0.98). Mean plasma cortisol concentration was greater (P⩽0.04) in CON compared with INR and AAC. No treatment effects were detected (P⩾0.37) for cattle ADG during feedlot receiving. Hence, INR and AAC increased liver concentrations of Co, Zn and Cu through preconditioning, but did not impact cattle performance and immunity responses during preconditioning and feedlot receiving. [ABSTRACT FROM PUBLISHER]

This experiment compared physiological and innate immunity responses in healthy beef heifers receiving a lipopolysaccharide (LPS) challenge and supplemented (OMN) or not (CON) with an immunomodulatory feed ingredient (Omnigen-AF; Phibro Animal Health, Teaneck, NJ). Eight Angus × Hereford non-pregnant, non-lactating, 2-yr old heifers were ranked by BW (473 ± 8 kg; recorded for 3 consecutive days prior to experiment) and assigned to a 2 × 2 Latin square design containing 2 period of 35 d each (d 0 to 34). Heifers were housed in individual pens and had free-choice access to meadow foxtail (Alopecurus pratensis L.) hay (59% TDN, 10.9% CP; DM basis), water and a commercial vitamin + mineral mix. Within each period, heifers received (as-fed basis) 227 g/d of dried distiller's grains (as-fed basis) including (OMN) or not (CON) 56 g of Omnigen-AF. On d 28 of each period (0800 h), heifers received an i.v. bolus dose (0.5 μg/kg of BW, diluted in 5 mL of 0.9% sterile saline) of bacterial LPS (Escherichia coli 0111:B4). Heifer DMI was recorded daily from d 0 to 34. Heifer intravaginal temperature was recorded every 10 min from d 28 to 34. Blood was collected every 30 min from -1 to 4 h, and at 5, 6, 24, 48, 72, 96, 120 and 144 h relative to LPS administration. No treatment effects were detected (P ≥ 0.29) for hay and total DMI. No treatment effects were detected (P ≥ 0.35) for vaginal temperature and plasma concentrations of cortisol, insulin, haptoglobin, and tumor necrosis-α, as well as mRNA expression of chemokine ligand 5, cyclooxygenase 2, interleukin 8, and tumor necrosis-α. All these variables increased (time effect, P < 0.01) for OMN and CON heifers and peaked at 4.5, 4, 2.5, 48, 2.5, 0.5, 2, 2.5, and 1.5 h, respectively, after LPS administration. Yet, peak plasma haptoglobin was greater (P < 0.01) in CON vs. OMN heifers (1.14 vs. 0.80 mg/mL, SEM = 0.07; respectively). Plasma glucose concentrations and mRNA expression of interleukin 8 receptor and L-selectin were also similar (P ≥ 0.61) between OMN and CON heifers, and decreased (time effect, P < 0.01) for both treatments reaching nadir levels at 3.5, 1, and 2.5 h after LPS administration. Collectively, OMN supplementation did not have a substantial impact on physiological and innate immunity responses in healthy beef heifers receiving a LPS challenge. [ABSTRACT FROM AUTHOR]

This experiment compared ovarian, uterine and conceptus factors associated with pregnancy establishment in Bos indicus beef cows according to estrus expression during a timed-AI protocol. One hundred lactating multiparous Nelore cows received a 2 mg injection of estradiol benzoate and an intravaginal progesterone (P4) releasing device on d -11, a 12.5 mg injection of PGF2α on d -4, P4 device removal in addition to 0.6 mg injection of estradiol cypionate and 300 IU injection of eCG on d -2, and timed-AI on d 0. All cows were inseminated by the same technician with semen from a single bull. An estrus detection patch was attached to the tailhed of each cow on d -2, and estrus expression was defined as removal of > 50% of the rub-off coating from the patch on d 0. Overall, 39 cows expressed estrus (EST), 55 did not express estrus (NOEST), and 6 cows lost their patch and were removed from the experiment. Transrectal ultrasonography was performed to verify ovulation and corpus luteum (CL) volume immediately before AI (d 0), on d 7 and 15. After ultrasonography on d 15, 60 cows (29 EST and 31 NOEST) diagnosed without the presence of a CL on d 0, but with a CL greater than 0.38 cm3 in volume on d 7 and 15, were assigned to conceptus collection via transcervical flushing with PBS followed by endometrial biopsy in the uterine horn ipsilateral to the CL. Blood samples were collected for whole blood RNA extraction (d 20) and pregnancy status was verified by transrectal ultrasonography (d 30) in cows not assigned to conceptus collection. Diameter of dominant follicle on d 0 was greater in EST vs. NOEST (13.8 vs. 12.4 mm; SEM = 0.4). Conceptus length and mRNA expression of prostaglandin E synthase and interferon-tau were greater (P ≤ 0.04) in EST vs. NOEST (2.74 vs. 0.98 cm, SEM = 0.59; 22.24 vs. 3.98 fold effect, SEM = 5.62; 8.17 vs. 2.78 fold effect, SEM = 1.72; respectively). Moreover, EST cows diagnosed as pregnant on d 30 had greater (P < 0.01) blood mRNA expression of myxovirus resistance 2 on d 20 compared with NOEST cohorts (57.5 vs. 27.1 fold effect; SEM = 5.05). Hence, estrus expression near the time of AI enhanced pregnancy establishment factors in B. indicus cows, including conceptus growth and mRNA expression of interferon-tau, as well as blood mRNA expression of a interferon-stimulated gene. [ABSTRACT FROM AUTHOR]

This experiment compared performance, health, and physiological responses of cattle supplemented with feed grade antibiotics or alternative feed additives during a 60-d receiving period. Newly-weaned Angus × Hereford calves (63 steers + 42 heifers) originating from 2 cow-calf ranches were obtained from an auction yard on d -2 and road-transported (800 km; 12-h) to a receiving yard. Upon arrival on d -1, shrunk BW was recorded and calves were grouped with free-choice hay, mineral supplement, and water. On d 0, calves were ranked by sex, source, and shrunk BW, and allocated to 1 of 21 pens. Pens were assigned to receive (7 pens/treatment) a free-choice total mixed ration containing: 1) lasalocid (360 mg/calf daily of Bovatec; Zoetis, Florham Park, NJ) + chlortetracycline (350 mg/calf of Aureomycin at cycles of 5-d inclusion and 2-d removal from diet; Zoetis) from d 0 to 31, and monensin only (360 mg/calf daily of Rumensin; Elanco Animal Health, Greenfield, IN) from d 32 to 60 (PC), 2) sodium saccharin-based sweetener (Sucram at 0.04 g/kg of diet DM; Pancosma SA; Geneva, Switzerland) + blend of natural oils eugenol, cinnamaldehyde, and capsicum (800 mg/calf daily of XTRACT Ruminants 7065; Pancosma SA) from d 0 to 31, and XTRACT only (800 mg/calf daily) from d 32 to 60 (EG), or 3) no supplemental ingredients (CON). Feed DMI was recorded from each pen, calves assessed for bovine respiratory disease (BRD) signs daily, and vaccinated against BRD pathogens on d 0 and 22. Final shrunk BW was recorded on d 61, and blood samples collected on d 0, 6, 11, 22, 32, 43, and 60. Calf ADG was greater (P = 0.04) in PC vs. EG and tended (P = 0.09) to be greater in PC vs. CON (1.59, 1.47, and 1.49 kg/d, respectively; SEM = 0.04), whereas G:F tended (P = 0.09) to be greater in PC vs. CON. Mean serum titers against bovine respiratory syncytial virus were greater in EG vs. PC (P = 0.04) and CON (tendency; P = 0.08). No further treatment differences were detected (P ≥ 0.23), including final BW, DMI, BRD incidence (66 ± 4%), plasma concentrations of cortisol, haptoglobin, and IGF-I, and serum titers against other BRD pathogens. Collectively, inclusion of alternative feed additives prevented the decrease in G:F when chlortetracycline and ionophores were removed from a receiving diet, and enhanced calf antibody response to vaccination against bovine respiratory syncytial virus. [ABSTRACT FROM AUTHOR]

Two experiments investigated the effects of supplementing Ca salts of soybean oil (CSSO) during early gestation on reproductive function and pregnancy rates to timed-AI in B. taurus beef cows. In Exp. 1, 771 lactating multiparous Angus cows were divided into 22 groups of approximately 35 cows/group, and timed-AI on d 0. After AI, groups were randomly assigned to receive (as-fed basis) 200 g/cow daily of a corn-based supplement and: 1) 100 g/cow daily of CSSO (n = 11; Essentiom; Church and Dwight Co., Inc., Princeton, NJ) or 2) 100 g/cow daily of prilled SFA (CON, n = 11; EnergyBooster; Milk Specialties, Eden Prairie, MN). Groups were maintained in individual pastures with free-choice access to forage, and offered treatments from d 0 to 21. Pregnancy status was determined on d 30 via transrectal ultrasonography. Cows receiving CSSO had greater (P = 0.01) pregnancy rates to timed-AI compared with CON cows (60.2 vs. 51.7%; SEM = 4.2). In Exp. 2, 90 lactating multiparous Angus cows housed in 18 drylot pens (5 cows/pen) were assigned to the same timed-AI program and treatments from Exp. 1 (9 pens/ treatment), receiving 20 kg/d (DM basis) of grass-alfalfa hay. Transrectal ultrasonography was performed to verify ovulation and corpus luteum (CL) volume immediately prior to AI, d 7, and 15. Within each treatment, 22 cows diagnosed without the presence of a CL on d 0, but with a CL greater than 0.38 cm3 on d 7 and 15, were assigned to conceptus collection via transcervical flushing with saline followed by endometrial biopsy on d 15. Both procedures were performed in the uterine horn ipsilateral to the CL. Blood samples were collected for whole blood RNA extraction (d 20) and pregnancy diagnosis (d 30; BioPRYN; Gold Standard Labs, Bowling Green, KY). Conceptus from cows receiving CSSO had greater (P ≤ 0.05) mRNA expression of interferon-tau vs. conceptus from CON cows (21.3 vs. 12.1 fold effect; SEM = 3.4). Within cows diagnosed as pregnant on d 30, blood mRNA expression of interferon-stimulated gene 15 and 20,50-oligoadenylate synthetase on d 20 were greater in CSSO vs. CON cows (43.1 vs. 29.8 fold effect, SEM = 4.6; 26.8 vs. 18.3 fold effect, SEM = 2.7; respectively). Hence, post-AI CSSO supplementation to beef cows increased pregnancy rates to timed-AI compared with non-supplemented cows, which can be attributed to increased mRNA expression of interferon-tau by the conceptus when CSSO is supplemented during early gestation. [ABSTRACT FROM AUTHOR]

This study compared vaginal temperature, physiologic, and productive parameters in lactating dairy cows supplemented or not with Omnigen-AF (Phibro Animal Health, Teaneck, NJ) during the summer months in a tropical environment. Thirty-two lactating, primiparous (n = 16) and multiparous (n = 16) pregnant Holstein x Gir cows were ranked by parity, days in milk, body weight, and body condition score (BCS), and assigned to receive (SUPP; n = 16) or not (CON; n = 16) Omnigen-AF (Phibro Animal Health, Teaneck, NJ) at 56 g/cow daily (as-fed basis). During the experimental period (d -6 to 56), cows were maintained in a single drylot pen with ad libitum access to water and a total mixed ration, and milked twice daily. Cows received Omnigen-AF mixed with 200 g of corn (as-fed basis) after the daily morning milking through self-locking head gates, whereas CON cows concurrently received 56 g of kaolin mixed with 200 g of corn. For feed intake evaluation, cows from both treatments were randomly divided in 4 groups of 8 cows each, and allocated to 8 individual feeding stations for 3 d. Intake was evaluated 4 times per group from d 1 to 56. From d -6 to 0, d 15 to 28, and d 43 to 56, cow vaginal temperature was recorded hourly. Environmental temperature-humidity index (THI) was also recorded hourly from d 15 to 28 and d 43 to 56. Cows were evaluated for body weight and BCS on d -6 and 56, individual milk production was recorded daily from d -6 to 56, and milk samples were collected on d -6, 0, 7, 14, 21, 28, 35, 42, 49, and 56 for analyses of somatic cell count and milk components. Blood samples were collected on d -6, -3, 0, 9, 15, 18, 21, 24, 27, 36, 45, 48, 51, 54, and 56. Results from samples or observations collected from d -6 to 0 were included as an independent covariate in each respective analysis. Environmental THI was 74.2 ± 0.5 and cows were exposed to THI >68 for 633 h within a total of 672 h of evaluation. Cows assigned to CON had greater vaginal temperature on d 28, 43, 45, and from d 48 to 55 (by 0.38 to 0.52%), as well as greater mean somatic cell count (by 97%) and serum haptoglobin concentrations (by 89%) compared with SUPP cows. Cows assigned to SUPP had greater mean dry matter intake (by 7%), BCS on d 56 (by 11%), and mean serum insulin concentrations (by 35%) compared with CON cows. Hence, SUPP ameliorated hyperthermia, improved nutritional status, and modulated systemic and mammary gland immune parameters in lactating dairy cows exposed to heat stress conditions. [ABSTRACT FROM AUTHOR]

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., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Embryonic mortality (EM) is a major factor limiting reproductive efficiency in cattle, and despite negative connotations related to reproductive performance, prostaglandin F 2α (PGF 2α ) is capable of being released by the uterus by Day 30 of gestation. Therefore, the objective was to evaluate differences in PGF 2α release after an oxytocin challenge between cows with high circulating concentrations of pregnancy-associated glycoproteins (PAGs) vs low PAG because of the association of increased PAG concentrations with pregnancy success. At Day 30 of gestation, pregnant cows were divided into oxytocin treatment (OT; n = 13) and control (CON; n = 12) groups. Treatment cows were further subdivided by circulating PAG concentration (high PAG, n = 7; and low PAG, n = 6). Blood samples were collected every 30 min beginning 1 h before oxytocin administration and continuing for 4 h. Prostaglandin F 2α metabolite (PGFM), progesterone, estradiol-17β (E2), and PAG concentrations were quantified. The peak concentration of PGFM occurred 2 h after oxytocin injection in treatment animals and returned to baseline levels by 4 h. No correlations were observed between PAG and PGFM, progesterone, or E2 concentrations (P > 0.05). There was no difference in initial or final PGFM concentrations between groups (P > 0.05). Progesterone and E2 concentrations decreased in cows after treatment of oxytocin (P < 0.05); however, only progesterone returned to basal concentrations by the end of the sampling period. In summary, cows with high vs low PAG concentrations at Day 30 of gestation have a similar PGFM response to oxytocin challenge., (Copyright © 2020 Elsevier Inc. All rights reserved.)