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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 compared performance and physiological responses of the offspring from cows supplemented with Ca salts of PUFA or SFA + MUFA during late gestation. Ninety-six multiparous, nonlactating, pregnant Angus × Hereford cows were ranked by BW, BCS, and age and divided into 24 groups of 4 cows/group at the end of their second trimester of gestation (d -7). Cows conceived during the same estrus synchronization + AI protocol, with semen from a single sire; hence, gestation length was 195 d for all cows at the beginning of the experiment (d 0). Groups were randomly assigned to receive (DM basis) 405 g/cow daily of soybean meal in addition to 1) 190 g/cow daily of Ca salts of PUFA based on eicosapentaenoic, docosahexaenoic, and linoleic acids or 2) 190 g/cow daily of Ca salts of SFA + MUFA based on palmitic and oleic acids (CON). Groups were maintained in 2 pastures (6 groups of each treatment/pasture) and received daily 10.1 kg/cow (DM basis) of grass-alfalfa hay. Groups were segregated into 1 of 12 drylot pens (6 by 18 m) and individually offered treatments 3 times/wk from d 0 until calving. Cow BW and BCS were recorded, and blood samples were collected on d -7 of the experiment and also within 12 h after calving. Calf BW was also recorded within 12 h of calving. Calves were weaned on d 280 of the experiment, preconditioned for 45 d (d 280 to 325), transferred to a growing lot on d 325, and moved to a finishing lot on d 445, where they remained until slaughter. At calving, PUFA-supplemented cows had a greater (P < 0.01) proportion (as % of total plasma fatty acids) of PUFA, including linoleic, linolenic, arachidonic, docosapentaenoic, and docosahexaenoic acids. At weaning, calves from CON-supplemented cows were older (P = 0.03), although no treatment differences were detected (P = 0.82) for calf weaning BW. During both growing and finishing phases, ADG was greater (P ≤ 0.06) in calves from PUFA-supplemented cows. Upon slaughter, HCW and marbling were also greater (P ≤ 0.05) in calves from PUFA-supplemented cows. Collectively, these results indicate that supplementing eicosapentaenoic, docosahexaenoic, and linoleic acids to late-gestating beef cows stimulated programming effects on postnatal offspring growth and carcass quality. Therefore, supplementing late-gestating beef cows with Ca salts of PUFA appears to optimize offspring productivity in beef production systems. [ABSTRACT FROM AUTHOR]

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]

One hundred eight Angus × Hereford steers, originating from 7 cow-calf were obtained from an auction yard on d -2 and transported by road (800 km; 12 h) to an experimental feedlot facility. Upon arrival on d -1, shrunk BW was recorded and steers were grouped with free-choice access to grass hay, mineral supplement, and water. On d 0, steers were ranked by source and shrunk BW and assigned to 1 of 18 pens (6 steers/pen). Pens were allocated to 1) no immunomodulatory ingredient supplementation during feedlot receiving (CON), 2) supplementation with OmniGen-AF (OMN; 22 g/steer daily, as-fed basis; Phibro Animal Health Corp., Teaneck, NJ) from d 0 to 30, or 3) 2 oral capsules of Stocker Immune Primer on d 0 + 15 g/steer daily (as-fed basis) of Stocker Preconditioned Premix (Ramaekers Nutrition, Santa Cruz, CA) from d 7 to 30 (IPF). From d 0 to 80, steers had free-choice access to grass hay and water and received a corn-based concentrate. Feed DMI was recorded from each pen, and steers were assessed for bovine respiratory disease (BRD) signs daily. Steers were vaccinated against BRD pathogens on d 0 and 21. Final shrunk BW was recorded on d 81, and blood samples were collected on d 0, 3, 7, 10, 14, 21, 31, 42, 56, and 73. Steer ADG and final BW were greater (P = 0.05) in CON steers than in OMN and IPF steers (1.23, 0.76, and 1.06 kg/d [SEM 0.06], respectively, and 320, 282, and 307 kg [SEM 4], respectively) and (P < 0.01) in IPF steers than in OMN steers. No treatment effects were detected (P = 0.76) for BRD incidence (66 ± 4%) and DMI, whereas G:F was greater (P < 0.01) in OMN steers than in CON steers. Mean plasma cortisol concentration was greater (P = 0.01) in CON steers than in OMN and IPF steers. Plasma haptoglobin concentrations tended (P = 0.10) to be greater in CON steers than in IPF steers on d 3, were greater (P = 0.04) in IPF steers than in CON steers on d 7, and tended (P = 0.10) to be less in OMN steers than in IPF and CON steers on d 21. Blood mRNA expression of interleukin 8 was greater (P = 0.05) in OMN and IPF steers than in CON steers on d 3 and in OMN steers than in CON and IPF steers on d 14. Blood mRNA expression of tumor necrosis-a was greater (P = 0.05) in OMN and IPF steers than in CON steers on d 10. Plasma IGF-I concentrations, serum antibody titers to BRD pathogens, and blood mRNA expression of chemokine ligand 5, cyclooxygenase 2, interleukin 8 receptor, and L-selectin did not differ (P = 0.21) among treatments. Collectively, the immunomodulatory feed ingredients evaluated herein impacted adrenocortical and innate immune responses but failed to mitigate BRD incidence and improve performance of receiving cattle. [ABSTRACT FROM AUTHOR]

This experiment compared DMI, ruminal forage degradability, and liquid parameters as well as physiological responses in beef cattle receiving a lipopolysaccharide (LPS) challenge or not. Eight ruminally cannulated Angus x Hereford steers (485 ± 16 kg BW) were housed in individual pens on d -7, ranked by BW, and allocated to 1 of 2 treatments administered on d 0: 1) an intravenous (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) or 2) a 5-mL i.v. injection of 0.9% sterile saline (CON). Steers had free-choice access to mixed alfalfa-grass hay, water, and a commercial vitamin + mineral mix during the experiment (d -7 to 6). Hay DMI was evaluated daily from d -5 to 6. Immediately prior to treatment administration (h 0), polyester bags containing 4 g of ground dietary hay (DM basis) were immersed into the rumen of each steer and incubated for 0, 4, 8, 12, 24, 36, and 48 h for DM and NDF degradability evaluation. Steers were also intraruminally pulse-dosed with 5 g of Co-EDTA immediately prior to treatment administration, and rumen fluid samples were collected at 0, 2, 4, 6, 8, 12, 16, and 24 h for ruminal liquid volume and dilution rate calculations. Blood was collected every 2 h from -2 to 8 h, every 4 h from 8 to 16 h, every 12 h from 24 to 72 h, and every 24 h from 96 to 144 h relative to treatment administration. Values obtained before treatment administration were used as a covariate within each respective analysis. Steers receiving LPS had less (P ≤ 0.03) DMI on d 0 and 1 compared with CON steers. Steers receiving LPS had reduced (P ≤ 0.05) rumen liquid volume and dilution rate as well as ruminal disappearance rate and effective degradability of DM and NDF compared with CON steers. Steers receiving LPS had greater (P ≤ 0.05) plasma tumor necrosis factor α at 2 h, greater plasma haptoglobin from 24 to 72 h, greater plasma cortisol from 12 to 16 h, greater serum NEFA from 6 to 48 h, greater plasma insulin and glucose at 2 h, reduced plasma glucose from 4 to 12 h, greater plasma cholecystokinin at 16 h, and greater plasma leptin concentrations at 8, 12, 16, 36, 48, and 60 h after treatment administration compared with CON steers. Hence, LPS administration transiently reduced DMI in steers via physiological reactions that modulate gastrointestinal motility and satiety centers in the central nervous system, in addition to potential host-microbiome endocrine interactions that impaired ruminal hay DM and NDF degradability. [ABSTRACT FROM AUTHOR]

This experiment compared mRNA expression of brain-blood biomarkers associated with stress-related psychological disorders, including post-traumatic stress disorder (PTSD), in beef cows from wolf-naive and wolf-experienced origins that were subjected to a simulated wolf encounter. Multiparous, non-pregnant, non-lactating Angus-crossbred cows from the Eastern Oregon Agricultural Research Center (Burns, OR; CON; n = 10) and from a commercial operation near Council, ID (WLF; n = 10) were used. To date, gray wolves are not present around Burns, OR, and thus CON were naive to wolves. Conversely, wolves are present around Council, ID, and WLF cows were selected from a herd that had experienced multiple wolf-predation episodes from 2008 to 2015. After a 60-d commingling and adaptation period, CON and WLF cows were allocated to groups A or B (d -1; 5 CON and 5 WLF cows in each group). On d 0, cows from group A were sampled for blood and immediately slaughtered, and samples were analyzed to evaluate inherent differences between CON and WLF cows. On d 1, cows from group B were exposed in pairs (1 CON and 1 WLF cow) to experimental procedures. Cows were sampled for blood, moved to 2 adjacent drylot pens (1 WLF and 1 CON cow/pen) and subjected to a simulated wolf encounter event for 20 min. The encounter consisted of (1) cotton plugs saturated with wolf urine attached to the drylot fence, (2) reproduction of wolf howls, and (3) three leashed dogs that were walked along the fence perimeter. Thereafter, another blood sample was collected and cows were slaughtered. Upon slaughter, the brain was removed and dissected for collection of the hypothalamus, and one longitudinal slice of the medial pre-frontal cortex, amygdala, and Cornu Ammonis (1 region of the hippocampus from both hemispheres). Within cows from group A, expression of c-Fos proto-oncogene in hippocampus and amygdala were greater (P < 0.01) in WLF vs. CON cows. Within cows from group B, expression of hippocampal brain-derived neurotrophic factor mRNA and expression of c-Fos proto-oncogene mRNA in hippocampus and amygdala were less (P ≤ 0.04) in WLF vs. CON cows. These are key biological markers known to be downregulated during stress-related psychological disorders elicited by fear, particularly PTSD. Hence, cows originated from a wolf-experienced herd presented biological evidence suggesting a psychological disorder, such as PTSD, after the simulated wolf encounter when compared with cows originated from a wolf-naive herd. [ABSTRACT FROM AUTHOR]

This experiment evaluated the effects of temperament on physiological, productive, and reproductive responses in Bos indicus beef cows. A total of 953 lactating, multiparous, non-pregnant Nelore cows (age = 99 ± 2 mo; days post-partum = 51.4 ± 0.3 d; BCS = 5.34 ± 0.04; BW = 430 ± 2 kg) were allocated into 8 groups of approximately 120 cows each. Groups were assigned to an estrus synchronization + timed- AI protocol at the beginning of the breeding season. Concurrently with AI, blood samples were collected, hair samples were clipped from the tail switch, and cow temperament was evaluated via chute score and exit velocity. Individual exit score was calculated within each group by dividing exit velocity into quintiles and assigning cows with a score from 1 to 5 (1 = slowest; 5 = fastest cow). Temperament scores were calculated by averaging cow chute score and exit score, and used to define cow temperament ( ≤ 3 = adequate, n = 726; ADQ; > 3 = excitable, n = 227; EXC). Cows not pregnant to AI were assigned to a second timed-AI protocol (n = 184 ADQ and 72 EXC) or exposed (n = 269 ADQ and 90 EXC) to bulls for 60 d. Pregnancy status was verified 30 d after each AI and 45 d after the breeding season via transrectal ultrasound. Cow age, BW, BCS, and d post-partum at the beginning of the breeding season were similar (P ≥ 0.27) between ADQ and EXC cows. At first timed-AI, EXC had greater (P < 0.01) serum cortisol but similar (P ≥ 0.87) serum haptoglobin and hair cortisol concentrations compared with ADQ cows (49.1 vs. 39.1 ng/mL of serum cortisol, SEM = 1.0). Pregnancy rate to first timed-AI tended (P = 0.09) to be less in EXC vs. ADQ cows (41.0 vs. 47.3%; SEM = 3.6), whereas no treatment differences were detected (P ≥ 0.23) for subsequent pregnancy outcomes. Calving rate was less (P = 0.04) in EXC vs. ADQ cows (68.3 vs. 74.8%; SEM = 2.2), which can be attributed to the greater (P = 0.05) pregnancy loss detected in EXC cows (9.9 vs. 5.9%; SEM = 1.4). Weaning rate tended (P = 0.09) to be less, whereas calf weaning BW and age were less (P ≤ 0.05) in EXC vs. ADQ cows (63.9 vs. 69.4%, SEM = 2.4; 209 vs. 212 d, SEM = 1; 204 vs. 210 kg, SEM = 2). Hence, kg of calf weaned/cow exposed to breeding was reduced (P = 0.04) in EXC vs. ADQ cows (130 vs. 146 kg, SEM = 5). In summary, B. indicus cows with excitable temperament had reduced reproductive performance and overall productivity compared to cohorts with adequate temperament when exposed to timed-AI + natural breeding. [ABSTRACT FROM AUTHOR]

The purpose of this review is to emphasize rangeland and landscape attributes that effect animal grazing behavior while highlighting successful approaches that have utilized this knowledge to devise supplementation strategies that improve the sustainability of grazing systems through modification of grazing behavior and pasture distribution, irrespective of animal nutrient requirements. Consequently, supplementation strategies are no longer formulated with the sole objective of addressing animal nutrient requirements. One of the principle drivers for this change in management philosophy is rangelands have become valued for many ecological services beyond forage for livestock. The threat of litigation and/or legal mandates that require land managers to consider the ecological, social, and economic impact of management decisions has increased scrutiny of livestock grazing. This has resulted in a significant body of research evaluating the ability of supplementation strategies to maintain or improve rangeland health and ecological function in a way that is economically viable. Herein, we will review the use of supplementation practices to alter livestock grazing location and control invasive species. Also, we will discuss the use of complimentary forages to bridge periods of inadequate forage quality. Rangeland-based livestock producers utilizing extensive landscapes will continue to face management challenges including changes in public land policy, anthropogenic development, climatic variability, invasive weeds, wildfire, water quality, and threatened and endangered species concerns. As an industry and a discipline we must continue to improve or ability to manage for “designed” landscapes that improve the economics of livestock production while maintaining or enhancing rangeland health and ecological function, thereby improving the long-term sustainability of grazing systems. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to compare hormonal, uterine, and conceptus factors associated with pregnancy establishment in Bos indicus beef cows supplemented or not with Ca salts of soybean oil (CSSO) for 21 d beginning after timed AI. One hundred lactating multiparous Nelore cows were allocated to 20 groups of 5 cows/group and timed inseminated on d 0 of the experiment. After AI, groups were randomly assigned to receive (as-fed basis) 100 g of protein–mineral mix + 100 g of ground corn per cow per day, in addition to 1) 100 g/cow daily of CSSO (n = 10) or 2) 100 g/cow daily of kaolin (CON; rumen-inert indigestible substance; n = 10). Groups were maintained in 4 Panicum maximum pastures (5 groups from the same treatment within each pasture) with ad libitum access to forage. Groups were segregated daily and individually offered treatments from d 0 to 21. Blood samples were collected and transrectal ultrasonography was performed to verify ovulation and corpus luteum (CL) volume immediately before AI (d 0) and on d 7 and 15. After ultrasonography on d 15, 60 cows (30 cows/treatment and 3 cows/group) 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. Additional 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. Cows receiving CSSO had greater (P ≤ 0.04) mean plasma linoleic acid concentration, plasma linoleic:linolenic acid ratio, plasma progesterone (P4) concentration, and CL volume during the experiment compared with CON cows. Moreover, CSSO supplementation increased (P ≤ 0.04) length and mRNA expression of prostaglandin E synthase and interferon-tau by the conceptus as well as blood mRNA expression of interferon-stimulated genes on d 20 in gestating cows. No treatment differences were detected (P ≥ 0.30) for endometrial mRNA expression of prostaglandin E synthase and cyclooxygenase-2. In summary, post-AI CSSO supplementation to B. indicus beef cows increased plasma concentration of linoleic acid and enhanced pregnancy establishment factors, which included CL development and plasma P4 concentration, conceptus growth, and mRNA expression of interferon-tau as well as blood mRNA expression of interferon-stimulated genes. [ABSTRACT FROM AUTHOR]

Ninety Angus × Hereford calves were ranked by sex, BW, and age and assigned to 1 of 3 vaccination schemes against the bovine respiratory disease complex: 1) vaccination at weaning (d 0) and a booster at feedlot entry (d 30; CON; n = 30), 2) vaccination 15 d before weaning (d -15) and a booster 15 d before feedlot entry (d 15; EARLY; n = 30), and 3) vaccination 15 d after weaning (d 15) and a booster 15 d after feedlot entry (d 45; DELAYED; n = 30). From d -15 to 7, calves were maintained as a single group on pasture. On d 8, calves were placed into 1 of 18 drylot pens (6 pens/treatment; 5 calves/pen) and fed alfalfa-triticale hay. On d 29, calves were transported 1,440 km in a livestock trailer and unloaded on d 30 at the same feed yard with the same pen arrangement used prior to transport. From d 30 to 75, calves were fed a receiving diet based on alfalfa–triticale hay + corn-based concentrate. Calf BW was recorded on 2 consecutive days (d -15, -14, 0, 1, 28, 29, 75, and 76). Blood samples were collected on d -15, 0, 15, 30, 45, 60, and 75. The EARLY calves had less (P ≤ 0.09) ADG before weaning (d -15 to -1); however, they had greater (P ≤ 0.01) ADG during feedlot receiving (d 30 to 75) compared with calves with the other treatments. During preconditioning (d 0 to 29), CON calves had greater (P ≤ 0.04) DMI compared with EARLY and DELAYED calves. During feedlot receiving, no treatment differences were detected (P ≥ 0.17) for hay or concentrate DMI, G:F, and morbidity and mortality rates. There were no treatment effects on calf BW at weaning and at the end of the preconditioning or receiving periods (P ≥ 0.65). Plasma concentrations of antibodies against Mannheimia haemolytica were greater (P ≤ 0.05) in EARLY calves than in CON and DELAYED calves on d 0, greater (P ≤ 0.04) for CON calves than for EARLY and DELAYED calves on d 15, greater (P ≤ 0.02) in DELAYED and EARLY calves than in CON calves on d 30, and greater (P = 0.03) in EARLY calves than in CON calves on d 75. Plasma concentrations of antibodies against bovine viral diarrhea viruses were greater (P ≤ 0.04) in EARLY calves than in CON and DELAYED calves on d 15 and greater for EARLY and CON calves than for DELAYED calves on d 30 and 45. Collectively, EARLY calves had greater plasma concentrations of antibodies against the evaluated pathogens at feedlot entry and increased ADG during receiving compared with their CON and DELAYED cohorts. Hence, anticipating initial and booster vaccinations against respiratory pathogens to provide both doses prior to feedlot entry appears to be a valid strategy to enhance cattle health and performance during feedlot receiving. [ABSTRACT FROM AUTHOR]

Eighty-four multiparous, nonlactating, pregnant Angus ? Hereford cows were ranked by pregnancy type (56 AI and 28 natural service), BW, and BCS and allocated to 21 drylot pens at the end of their second trimester of gestation (d 0). Pens were assigned to receive forage-based diets containing 1) sulfate sources of Cu, Co, Mn, and Zn (INR); 2) an organic complexed source of Cu, Mn, Co, and Zn (AAC; Availa 4; Zinpro Corporation, Eden Prairie, MN); or 3) no supplemental Cu, Co, Mn, and Zn (CON). Diets were offered from d 0 until calving and formulated to meet requirements for energy, protein, macrominerals, Se, I, and vitamins. The INR and AAC diets provided the same daily amount of Cu, Co, Mn, and Zn. Cow BW and BCS were recorded and liver samples were collected on d -10 and 2 wk (d 75) before the calving season. Within 3 h after calving, calf BW was recorded, liver samples were collected, and the expelled placenta was retrieved (n = 47 placentas). Calves were weaned on d 283 of the experiment, preconditioned for 45 d (d 283 to 328), transferred to a growing lot on d 328, and moved to a finishing lot on d 440 where they remained until slaughter. Liver Co, Cu, and Zn concentrations on d 75 were greater (P = 0.05) for INR and AAC cows compared with CON cows, whereas INR cows had reduced (P = 0.04) liver Co but greater (P = 0.03) liver Cu compared with AAC cows. In placental cotyledons, Co concentrations were greater (P = 0.05) in AAC and INR cows compared with CON cows, whereas Cu concentrations were increased (P = 0.05) only in AAC cows compared with CON cows. Calves from INR and AAC cows had greater (P < 0.01) liver Co concentrations at birth compared with calves from CON cows. Liver Cu and Zn concentrations at birth were greater (P = 0.05) in calves from AAC cows compared with cohorts from CON cows. Weaning BW was greater (P = 0.05) in calves from AAC cows compared with cohorts from CON cows, and this difference was maintained until slaughter. In the growing lot, calves from AAC cows had reduced (P < 0.01) incidence of bovine respiratory disease compared with CON and INR cohorts. Collectively, these results suggest that feeding the AAC diet to late-gestating beef cows stimulated programming effects on postnatal offspring growth and health compared with the CON diet. Therefore, supplementing late-gestating beef cows with an organic complexed source of Co, Cu, Zn, and Mn instead of no supplementation appears to optimize offspring productivity in beef production systems. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to evaluate temperament, physiological, and reproductive variables in Bos indicus beef cows assigned to an estrus synchronization + timed AI protocol including eCG administration, 48-h temporary calf weaning (TCW), or TCW + meloxicam administration. A total of 943 lactating, multiparous, nonpregnant Nelore cows, allocated into 8 groups of approximately 120 cows each, were assigned to the experiment. Groups were maintained in individual pastures and assigned to the following estrus synchronization + timed AI protocol: a 2-mg injection of estradiol benzoate and an intravaginal progesteronereleasing device (CIDR) on d 0, a 12.5-mg injection of PGF2α on d 7, CIDR removal in addition to a 0.6- mg injection of estradiol cypionate on d 9, and timed AI on d 11. Within each group, cows were randomly assigned on d 9 to 1) TCW from d 9 to 11 (TCW-CON; n = 317), 2) no TCW and a 300-IU injection of eCG on d 9 (NOTCW; n = 311), and 3) TCW-CON in addition to meloxicam administration (intramuscular; 0.5 mg/kg BW) on d 9 (TCW-MEL; n = 315). Cow BW and BCS were assessed on d 0. On d 9 and 11, blood samples were collected, and cow temperament was evaluated via chute score and exit velocity. Pregnancy status was verified 30 d after timed AI via transrectal ultrasonography. No treatment differences were detected (P ≥ 0.23) for cow age, days postpartum, BW, and BCS on d 0 of the estrus synchronization + timed AI protocol. No treatment effects were detected (P ≥ 0.41) for any of the temperament variables evaluated. A treatment × day interaction was detected (P = 0.02) for serum cortisol concentrations, which were similar (P = 0.55) between treatments on d 9 but greater (P ≤ 0.05) in TCW-CON and TCW-MEL compared with NOTCW cows on d 11. No treatment effects were detected (P = 0.90) for serum haptoglobin concentrations, which decreased from d 9 to 11 in all treatments (day effect; P < 0.01). No treatment differences were detected (P = 0.84) for pregnancy rates to timed AI. In summary, TCW during estrus synchronization did not impact temperament or serum haptoglobin concentrations in B. indicus beef cows but increased serum cortisol concentrations compared with cows not assigned to TCW, although such an outcome was not sufficient to impact pregnancy rates to timed AI. Moreover, administration of meloxicam did not alleviate the TCW-induced increase in serum cortisol concentrations and failed to benefit pregnancy rates to timed AI in B. indicus beef cows. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of oral meloxicam administration on metabolic, inflammatory, and acute-phase responses of beef cattle receiving a lipopolysaccharide (LPS) challenge (Exp. 1; d -1 to 6) or vaccinated against respiratory pathogens (Exp. 2; d 7 to 21). Twenty-one Angus steers (n = 11) and heifers (n = 10) were housed in individual pens on d -15 and were offered free-choice water, mineral-vitamin mix, and hay until d 21. In Exp. 1, cattle were ranked on d -1 by sex and BW and assigned to 1) oral meloxicam administration (1 mg/kg BW daily) from day -1 to 6 (MEL8), 2) oral meloxicam administration (1 mg/kg BW) on d 0 and oral lactose monohydrate administration (1 mg/kg BW) on d -1 and from d 1 to 6 (MEL1), or 3) oral lactose monohydrate administration (1 mg/ kg BW daily) from d -1 to 6 (CON). On d 0, cattle received an intravenous LPS bolus (0.5 µg/kg BW) concurrently with treatment administration. Rectal temperature (RTEMP) was assessed, and blood samples were collected at -2, 0, 2, 4, 6, 8, 12, 16, 24, 36, 48, 60, 72, 96, 120, and 144 h relative to LPS administration. No treatment effects were detected (P ≥ 0.36) for RTEMP, concentrations of serum tumor necrosis factor α (TNFα), plasma haptoglobin, cortisol, insulin, and leptin, as well as blood mRNA expression of TNFα and cyclooxygenase-2, although all variables increased (P < 0.01) across treatments after LPS administration. In Exp. 2, cattle received the same treatments that they were assigned to in Exp. 1 from d 7 to d 13 and were vaccinated against respiratory pathogens concurrently with treatment administration on d 8. Blood samples were collected, and RTEMP was assessed as in Exp. 1 in addition to 168, 240, and 336 h relative to vaccination. No treatment effects were detected (P ≥ 0.26) for RTEMP, the same plasma and serum variables evaluated in Exp. 1, and serum concentrations of antibodies against Mannheimia haemolytica or serum titers against bovine respiratory syncytial virus, bovine herpesvirus-1, bovine viral diarrhea virus-1, and parainfluenza-3 virus. All variables increased (P < 0.01) across treatments after vaccination, except for serum TNFα and titers against bovine viral diarrhea virus-1 (P ≥ 0.40). Collectively, this study found no evidence that oral meloxicam administration, at the doses and intervals utilized herein, mitigated the metabolic, inflammatory, and acute-phase reactions elicited by LPS administration or vaccination against respiratory pathogens. [ABSTRACT FROM AUTHOR]

This experiment compared growth, physiological, and reproductive responses of beef heifers with (MI) or without (CON) access to a creep-feeder, as a manner to stimulate metabolic imprinting while nursing their dams. On day 0, 60 Angus×Hereford heifers were ranked by BW and age (140±3 kg and 68±3 days), and assigned to pairs so all ranking criteria were similar between heifers within each pair. On day 1, pairs were randomly assigned to MI (n=15) or CON (n=15). From day 1 to 51, MI pairs and their dams were allocated to 15 drylot pens where heifers had ad libitum access to a corn-based supplement through a creep-feeder. The CON pairs and their dams were maintained in an adjacent single drylot pen. From day 52 to 111, treatments were managed as a single group on a semiarid range pasture. On day 111, heifers were weaned and allocated to two pastures (one pasture/treatment), receiving hay and a corn-based concentrate until day 326. Heifer BW was recorded before and at the end of the creep-feeding period (day 1 to 51), and on days 112 and 326. On days 0, 51, 111, 187, 261, and 325, jugular blood was collected and real-time ultrasonography for longissimus muscle depth and backfat thickness assessment was performed. Blood was also collected every 10 days from days 113 to 323 for puberty evaluation via plasma progesterone. Liver and subcutaneous fat biopsies were performed on days 51, 111, 261 and 325. Average daily gain was greater (P<0.01) for MI than CON from day 1 to 51, tended (P=0.09) to be greater for CON than MI from day 112 to 326, while BW on day 326 was similar between treatments. On day 51, MI had greater (P⩽0.01) plasma IGF-I and glucose concentrations, as well as mRNA expression of hepatic pyruvate carboxylase and adipose fatty acid synthase than CON. On days 261 and 325, plasma insulin concentrations were greater (P⩽0.03) in CON than MI. Mean mRNA expression of hepatic IGF-I and adipose peroxisome proliferator-activated receptor gamma were greater (P⩽0.05) in MI than CON. No treatment effects were detected for puberty attainment rate. In conclusion, supplementing nursing heifers via creep-feeding for 50 days altered physiological and biochemical variables suggestive of a metabolic imprinting effect, but did not hasten their puberty attainment. [ABSTRACT FROM PUBLISHER]

The objective of this study was to evaluate intake, metabolic, inflammatory, and acute-phase responses in beef heifers vaccinated against pathogens that cause bovine respiratory disease (BRD). Eighteen weaned Angus heifers (initial BW 257 ± 3 kg; initial age 245 ± 2 d) were ranked by BW and allocated to 2 groups, which were assigned to 2 experiments of 7 d and the following treatments on d 1 of each experiment: 1) revaccinated against infectious bovine rhinotracheitis virus, parainfluenza-3 virus, bovine respiratory syncytial virus, bovine viral diarrhea Types 1 and 2 viruses, and Mannheimia haemolytica (VAC; 2 mL [s.c.]) and 2) receiving a 2-mL s.c. injection of 0.9% sterile saline (CON). The group receiving VAC in Exp. 1 was assigned to CON in Exp. 2 and vice versa. Heifers were weaned 21 d before Exp. 1, when they all received the first dose of the aforementioned vaccine. Heifers were maintained in individual pens and offered free-choice mixed alfalfa-grass hay and 3.5 kg/d (DM basis) of a corn-based supplement throughout the study. During Exp. 1, hay and concentrate intake were evaluated daily. During Exp. 2, blood samples were collected before (-2 and 0 h) and at 2, 4, 6, 8, 12, 16, 24, 36, 48, 60, 72, 96, 120, 144, and 168 h after treatment administration. In Exp. 1, treatment ? day interactions were detected (P < 0.01) for forage intake and total DMI; these parameters were reduced (P = 0.05) in VAC heifers compared with CON heifers on d 1 and 2 by an average of 1.7 and 0.8 kg (DM basis), respectively. In Exp. 2, mean serum tumor necrosis factor a (TNFa) concentration was greater (P = 0.05) in VAC heifers compared with CON heifers and treatment ? hour interactions were detected for all plasma variables (P = 0.02), whereas a similar tendency was detected (P = 0.09) for blood TNFa mRNA expression. Haptoglobin concentrations were greater (P = 0.05) in VAC heifers compared with CON heifers from 16 to 120 h. Blood TNFa mRNA expression was greater (P = 0.05) in VAC heifers compared with CON heifers at 12 h. Cortisol concentrations were greater (P = 0.05) in VAC heifers compared with CON heifers from 2 to 16 h. Insulin concentration was greater (P = 0.02) in VAC heifers compared with CON heifers at 2 h. Leptin concentrations were greater (P = 0.05) in VAC heifers compared with CON heifers from 6 to 16 h. In conclusion, vaccinating beef heifers against BRD pathogens decreased forage intake and total DMI during the 2 d following vaccination in Exp. 1, which can be associated with transient metabolic, inflammatory, and acute-phase responses elicited by vaccination in Exp. 2. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to determine if frequency of protein supplementation impacts physiological responses associated with reproduction in beef cows. Fourteen nonpregnant, nonlactating beef cows were ranked by age and BW and allocated to 3 groups. Groups were assigned to a 3 × 3 Latin square design, containing 3 periods of 21 d and the following treatments: 1) soybean meal supplementation daily (D), 2) soybean meal supplementation 3 times/week (3WK), and 3) soybean meal supplementation once/week (1WK). Within each period, cows were assigned to an estrus synchronization protocol: 100 μg of GnRH + controlled internal drug release device (CIDR) containing 1.38 g of progesterone (P4) on d 1, 25 mg of PGF2α on d 8, and CIDR removal + 100 μg of GnRH on d 11. Grassseed straw was offered for ad libitum consumption. Soybean meal was individually supplemented at a daily rate of 1 kg/cow (as-fed basis). Moreover, 3WK was supplemented on d 0, 2, 4, 7, 9, 11, 14, 16, and 18 whereas 1WK was supplemented on d 4, 11, and 18. Blood samples were collected from 0 (before) to 72 h after supplementation on d 11 and 18 and analyzed for plasma urea-N (PUN). Samples collected from 0 to 12 h were also analyzed for plasma glucose, insulin, and P4 (d 18 only). Uterine flushing fluid was collected concurrently with blood sampling at 28 h for pH evaluation. Liver biopsies were performed concurrently with blood sampling at 0, 4, and 28 h and analyzed for mRNA expression of carbamoyl phosphate synthetase I (CPS-I; h 28) and CYP2C19 and CYP3A4 (h 0 and 4 on d 18). Plasma urea-N concentrations were greater (P < 0.01) for 1WK vs. 3WK from 20 to 72 h and greater (P < 0.01) for 1WK vs. D from 16 to 48 h and at 72 h after supplementation (treatment × hour interaction, P < 0.01). Moreover, PUN concentrations peaked at 28 h after supplementation for 3WK and 1WK (P < 0.01) and were greater (P < 0.01) at this time for 1WK vs. 3WK and D and for 3WK vs. D. Expression of CPS-I was greater (P < 0.01) for 1WK vs. D and 3WK. Uterine flushing pH tended (P ≤ 0.10) to be greater for 1WK vs. 3WK and D. No treatment effects were detected (P ≥ 0.15) on expression of CYP2C19 and CYP3A4, plasma glucose, and P4 concentrations, whereas plasma insulin concentrations were greater (P ≤ 0.03) in D and 3WK vs. 1WK. Hence, decreasing frequency of protein supplementation did not reduce uterine flushing pH or plasma P4 concentrations, which are known to impact reproduction in beef cows. [ABSTRACT FROM AUTHOR]

This experiment evaluated the effects of meloxicam administration on physiological and performance responses of transported cattle during feedlot receiving. Eighty-four Angus x Hereford steers were ranked by BW on d -10 and assigned to 21 dry lot pens. From d -10 to 0, pens were fed alfalfa-grass hay ad libitum and 2.4 kg/steer daily (DM basis) of a corn-based concentrate. On d 0, pens were randomly assigned to 1 ) transport for 1,440 km in a livestock trailer and oral administration of meloxicam (1 mg/kg of BW) at loading (d 0), unloading (d 1 ), and daily from d 2 to 7 of feedlot receiving (MEL; n = 7); 2) the same transportation and treatment schedule of MEL but oral administration of lactose monohydrate (1 mg/kg of BW) instead of meloxicam (TRANS; n = 7); or 3) no transport and oral administration of lactose monohydrate ( 1 mg/kg of BW) concurrently with treatment administration to MEL and TRANS (CON; n = 7). Upon arrival (d 1), MEL and TRANS steers returned to their pens for a 21-d feedlot receiving with the same diet offered from d -10 to 0. Treatments were administered to steers via oral drench on d 0 and 1 or mixed daily with the concentrate from d 2 to 7. Full BW was recorded before (d -2, -1, and 0) treatment application and at the end of experiment (d 20, 21, and 22) for ADG calculation. Daily DMI was recorded from d 1 to 21. Blood samples were collected on d 0, 1, 3, 5, 7, 10, 14, and 21. During the initial 7 d of feedlot receiving, hay and total DMI were reduced (P ≤ 0.03) in TRANS vs. CON and MEL and similar between CON and MEL (P > 0.26), whereas concentrate DMI did not differ (P = 0.16) among treatments. Mean ADG was reduced (P ≤ 0.03) in TRANS vs. MEL and CON but similar {P = 0.82) between MEL and CON. Moreover, TRANS had reduced G:F vs. CON (P = 0.01 ) and MEL (P= 0.05), whereas G:F was similar (P = 0.39) between CON and MEL. Serum NEFA concentrations were greater (P <0.01) for TRANS and MEL vs. CON on d 1. Plasma haptoglobin concentrations were greater (P ≤ 0.03) for TRANS vs. CON and MEL on d 5 and greater (P≤ 0.03) for CON vs. TRANS on d 10. Plasma ceruloplasmin concentrations were greater (P ≤ 0.04) for TRANS vs. CON on d 3, 5, 7, 10, and 14, greater (P ≤ 0.03) for TRANS vs. MEL on d 5 and 7, and also greater (P = 0.05) for MEL vs. CON on d 3. In conclusion, meloxicam administration to feeder steers modulated the haptoglobin and ceruloplasmin responses and prevented the performance losses caused by long-distance transportation. [ABSTRACT FROM AUTHOR]

This experiment evaluated the influence of supplement composition on performance, reproductive, and metabolic responses of Angus x Hereford heifers consuming a low-quality cool-season forage (8.7% CP and 57% TDN). Sixty heifers (initial age = 226 ± 3 d) were allocated into 15 drylot pens (4 heifers/pen and 5 pens/treatment) and assigned to 1) supplementation with soybean meal (PROT), 2) supplementation with a mixture of cracked com, soybean meal, and urea (68:22:10 ratio, DM basis; ENER), or 3) no supplementation (CON). Heifers were offered meadow foxtail (Alopecurus pratensis L.) hay for ad libitum consumption during the experiment (d-10 to 160). Beginning on d 0, PROT and ENER were provided daily at a rate of 1.30 and 1.40 kg of DM/heifer to ensure that PROT and ENER intakes were isocaloric and isonitrogenous. Hay and total DMI were recorded for 5 consecutive days during each month of the experiment. Blood was collected every 10 d for analysis of plasma progesterone to evaluate puberty attainment. Blood samples collected on d-10, 60, 120, and 150 were also analyzed for plasma concentrations of plasma urea N (PUN), glucose, insulin, IGF-I, NEFA, and leptin. Liver samples were collected on d 100 from 2 heifers/pen and analyzed for mRNA expression of genes associated with nutritional metabolism. No treatment effect was detected (P = 0.33) on forage DMI. Total DMI, ADG, and mean concentrations of glucose, insulin, and IGF-I as well as hepatic mRNA expression of IGF-I and IGFBP-3 were greater (P ≤ 0.02) for PROT and ENER compared with CON and similar between PROT and ENER (P ≥ 0.13). Mean PUN concentrations were also greater (P <0.01) for PROT and ENER compared with CON, whereas PROT heifers had greater (P <0.01) PUN compared with ENER. Plasma leptin concentrations were similar between ENER and PROT (P ≥ 0.19) and greater (P ≤ 0.03) for ENER and PROT compared with CON on d 120 and 150 (treatment x day interaction, P = 0.03). Hepatic mRNA expression of mitochondrial phosphoenolpyruvate carboxykinase was greater (P = 0.05) in PROT compared with CON and ENER and similar between CON and ENER (P = 0.98). The proportion of heifers pubertal on d 160 was greater (P <0.01) in ENER compared with PROT and CON and similar between PROT and CON (P = 0.38). In conclusion, beef heifers consuming a low-quality cool-season forage had a similar increase in DMI, growth, and overall metabolic status if offered supplements based on soybean meal or com at 0.5% of BW. [ABSTRACT FROM AUTHOR]

Two experiments evaluated the influence of supplement composition on ruminai forage disappearance, perfomiance, and physiological responses of Angus x Hereford cattle consuming a low-quality cool-season for-age (8.7% CP and 57% TDN). In Exp. 1, 6 rumen-fistulated steers housed in individual pens were assigned to an incomplete 3 x 2 Latin square design containing 2 periods of 11 d each and the following treatments: 1) supplementation with soybean meal (PROT), 2) supplementation with a mixture of cracked corn, soybean meal, and urea (68:22:10 ratio, DM basis; ENER), or 3) no supplementation (CON). Steers were offered meadow foxtail (Alopecurus praten- sis L.) hay for ad libitum consumption. Treatments were provided daily at 0.50 and 0.54% of shrunk BW/steer for PROT and ENER, respectively, to ensure that PROT and ENER intakes were isocaloric and isonitrogenous. No treatment effects were detected on rumen disappearance parameters of forage DM (P ≥ 0.33) and NDF (P ≥ 0.66). In Exp. 2, 35 pregnant heifers were ranked by initial BW on d -7 of the study, allocated into 12 feedlot pens (4 pens/ treatment), and assigned to the same treatments and forage intake regimen as in Exp. 1 for 19 d. Treatments were fed once daily at 1.77 and 1.92 kg of DM/heifer for PROT and ENER, respectively, to achieve the same treatment intake as percent of initial BW used in Exp. 1 (0.50 and 0.54% for PROT and ENER, respectively). No treatment effects (P = 0.17) were detected on forage DMI. Total DMI was greater (P < 0.01) for PROT and ENER compared with CON and similar between PROT and ENER (P = 0.36). Accordingly, ADG was greater (P = 0.01) for PROT compared with CON, tended to be greater for ENER compared with CON (P = 0.08), and was similar between ENER and PROT (P = 0.28). Heifers receiving PROT and ENER had greater mean concentrations of plasma glucose (P = 0.03), insulin (P ≤ 0.09), IGF-I (P ≤ 0.04), and progesterone (P = 0.01) compared to CON, whereas ENER and PROT had similar concentrations of these variables (P ≥ 0.15). A treatment x hour interaction was detected (P < 0.01) for plasma urea N (PUN), given that PUN concentrations increased after supplementation for ENER and PROT (time effect, P < 0.01) but did not change for CON (time effect, P = 0.62). In conclusion, beef cattle consuming low-quality cool-season forages had similar ruminai forage disappearance and intake, performance, and physiological status if offered supplements based on soybean meal or com at 0.5% of BW. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to compare fatty acid (FA) concentrations in plasma and reproductive tissues as well as hormones and expression of genes associated with pregnancy establishment in beef cows supplemented or not with Ca salts of soybean oil (CSSO) beginning after timed AI. Ninety nonlactating muciparous Nelore (Bos indicus) cows were timed inseminated on d 0 of the experiment and divided into 18 groups of 5 cows/group. Groups were randomly assigned to receive (as-fed basis) 100 g of a protein-mineral mix plus 100 g of ground corn per cow daily in addition to 1) 100 g/cow daily of CSSO (n = 9) or 2) 100 g/cow daily of kaolin (CON; rumeninert indigestible substance; n = 9). All groups were maintained in a single Brachiaria brizanta pasture (24 ha) with ad libitum access to forage and water. However, groups were segregated daily and offered treatments individually at the working facility during the experimental period (d 0 to 18). Blood samples were collected and transrectal ultrasonography was performed to verify ovulation and estimate corpus luteum (CL) volume immediately before AI (d 0) and on d 7 and 18 of the experiment. On d 19,36 cows (18 cows/ treatment; 2 cows/group) 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 18 were slaughtered for collection of conceptus, uterine luminal flushing, and tissue samples from the CL and endometrium. Cows receiving CSSO had greater concentrations of linoleic and other ω-6 FA in plasma (P < 0.01), endometrium (P ⩽ 0.05), CL (P ⩽ 0.05), and conceptus (P ⩽ 0.08) compared to CON. On d 7 of the experiment, CSSO-supplemented cows had greater plasma progesterone concentrations (P < 0.01) and CL volume (P = 0.02) compared to CON, whereas no treatment effects were detected (P ⩾ 0.15) for these parameters on d 18 (treatment × day interaction; P < 0.01). Cows receiving CSSO tended (P = 0.09) to have greater concentrations of interferon-tau in the uterine flushing media compared with CON. However, no treatment effects were detected for mRNA expression genes associated with pregnancy establishment in endometrial, CL, and conceptus samples (P ⩾ 0.12). In summary, supplementing beef cows with 100 g of CSSO beginning after AI favored incorporation of ω-6 FA into their circulation, reproductive tissues, and conceptus, without impacting expression of genes associated with pregnancy establishment on d 19 of gestation. [ABSTRACT FROM AUTHOR]

This experiment evaluated temperament, vaginal temperature, and plasma Cortisol in beef cows from wolf-na'ive and wolf-experienced origins that were subjected to a simulated wolf encounter. Multiparous, pregnant, nonlactating Angus-crossbreed cows from the Eastern Oregon Agricultural Research Center located near Burns, OR (CON; n = 50), and from a commercial operation near Council, ID (WLF; n = 50), were used. To date, grey wolves are not present around Burns, OR, and thus CON were naïve to wolves. Conversely, wolves are present around Council, ID, and WLF cows were selected from a herd that had experienced multiple confirmed wolf-predation episodes from 2008 to 2012. Following a 50-d commingling and adaptation period, CON and WLF cows were ranked by temperament, BW, and BCS and allocated to 5 groups (d 0; 10 CON and 10 WLF cows/group). Groups were individually subjected to the experimental procedures on d 2 (« = 3) and d 3 (n = 2). Before the simulated wolf encounter, cow temperament was assessed and blood samples and vaginal temperatures (using intravaginal data loggers) were collected (presimulation assessments). Cows were then sorted by origin, moved to 2 adjacent drylot pens (10 WLF and 10 CON cows/pen), and subjected to a simulated wolf encounter event for 20 min, which consisted of 1 ) cotton plugs saturated with wolf urine attached to the drylot fence, 2) continuous reproduction of wolf howls, and 3) 3 leashed dogs that were walked along the fence perimeter. Thereafter, WLF and CON cows were commingled and returned to the handling facility for postsimulation assessments, which were conducted immediately after exposure to wolf-urine-saturated cotton plugs, wolf howl reproduction, and 20-s exposure to the 3 dogs while being restrained in a squeeze chute. Chute score, temperament score, and plasma Cortisol concentration increased (P ≤ 0.01) from pre- to postsimulation assessment in WLF but did not change in CON cows (P ≥ 0.19). Exit velocity decreased (P = 0.01) from pre- to postsimulation assessment in CON but did not change (P = 0.79) in WLF cows. In addition, WLF cows had a greater (P = 0.03) increase in temperature from pre- to postsimulation assessments compared with CON cows. In conclusion, the simulated wolf encounter increased excitability and fear-related physiological stress responses in cows that originated from a wolf-experienced herd but not in cows that originated from a wolf-naïve herd. [ABSTRACT FROM AUTHOR]

Angus x Hereford steers (n = 42) and heif-ers (n = 21) were ranked by gender and BW on d 0 of the experiment and randomly assigned to 1 of 3 treatments: 1 ) no transport and full access to feed and water (CON); 2) continuous road transport for 1,290 km (TRANS), or 3) road transport for 1,290 km, with rest stops every 430 km (STOP; total of 2 rest stops). Treatments were applied from d 0 to 1 of the experiment. Cattle from TRANS and STOP treatments were transported in sepa-rate commercial livestock trailers, within a single 2.1 x 7.2 m compartment, but through the exact same route. During each rest stop, STOP cattle were unloaded and offered mixed alfalfa-grass hay and water for ad libitum consumption for 2 h. Upon arrival of STOP and TRANS on d 1, cattle were ranked by sex and BW within each treatment and assigned to 21 feedlot pens (7 pens/treat-ment; 2 steers and 1 heifer/pen). Full BW was recorded before (d -1 and 0) treatment application and at the end of experiment (d 28 and 29). Total DMI was evaluat-ed daily from d 1 to 28. Blood samples were collected on d 0 (before loading of TRANS and STOP cattle), 1 (immediately after unloading of TRANS and STOP cat-tle), 4, 7, 10, 14, 21, and 28. Body weight shrink from d 0 to d 1 was reduced (P < 0.01) in CON compared to TRANS and STOP, and reduced in STOP compared to TRANS. Mean ADG was greater (P < 0.05) in CON compared to TRANS and STOP, but similar (P = 0.68) between TRANS and STOP. No treatment effects were detected (P >0.18) on hay, concentrate, and total DMI. Mean G:F was greater (P = 0.05) in CON compared to STOP, tended to be greater (P = 0.08) in CON compared to TRANS, and similar (P = 0.85) between TRANS and STOP. Plasma Cortisol concentrations were greater (P < 0.04) in TRANS compared to CON and STOP on d 1, and greater (P = 0.04) in TRANS compared to CON on d 4. Serum NEFA concentrations were greater (P < 0.01) in TRANS compared to CON and STOP on d 1, and greater (P < 0.05) in TRANS compared to CON on d 4 and 7. Mean plasma ceruloplasmin concentra-tions were similar (P = 0.19) among treatments. Plasma haptoglobin concentrations were greater (P < 0.04) in TRANS compared to CON and STOP on d 1, and in STOP compared to CON on d 1. In conclusion, inclu-sion of rest stops during a 1,290-km transport prevented the increase in circulating Cortisol and alleviated the NEFA and haptoglobin response elicited by transport, but did not improve feedlot receiving performance of transported cattle. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the effects of flunixin meglumine administration on physiologi-cal and performance responses of transported cattle during feedlot receiving. Forty-five Angus x Hereford steers were ranked by BW on d 0 and assigned to 1 of 3 treatments: 1) transport for 1,280 1cm in a commercial livestock trailer and administration of flunixin meglumine (1.1 mg/kg BW; intravenous) at loading (d 0) and unload-ing (d 1 ; FM), 2) transport for 1,280 km in a commercial livestock trailer and administration of 0.9% saline (0.022 mL/kg BW; intravenous) at loading (d 0) and unloading (d 1 ; TRANS), or 3) no transport and administration of 0.9% saline (0.022 mL/kg BW; intravenous) concur-rently with loading (d 0) and unloading (d 1) of FM and TRANS cohorts (CON). Upon arrival and processing for treatment administration on d 1, steers within each treat-ment were ranked by BW and assigned to 15 feedlot pens (5 pens/treatment, 3 steers/pen). Full BW was recorded before (d -1 and 0) treatment application and at the end of experiment (d 28 and 29) for ADG calculation. Total DMI was evaluated daily from d 1 to 28. Blood samples were collected on d 0 (before treatment administration), 1 (after unloading but before treatment administration), 4,7, 10,14,21, and 28. Body weight shrink from d 0 to 1 was less (P < 0.01 ) in CON vs. FM and TRANS but simi-lar (P = 0.94) between TRANS and FM. Mean ADG was greater (P < 0.04) in CON vs. FM and TRANS but similar (P = 0.69) between TRANS and FM. No treatment effects were detected on DMI, but CON had greater G:F vs. TRANS (P = 0.08) and FM (P = 0.02), whereas G:F was similar (P = 0.68) between TRANS and FM. Mean plas-ma Cortisol concentrations tended (P < 0.09) to be greater in TRANS vs. FM and CON but was similar (P = 0.87) between CON and FM. Plasma NEFA concentrations were greater (P < 0.02) for TRANS and FM vs. CON on d 1 and greater (P < 0.04) for FM vs. TRANS and CON on d 4. Plasma ceruloplasmin concentrations were greater (P ≤ 0.03) for TRANS vs. CON on d 1, 4, and 7, greater (P ≤ 0.05) for TRANS vs. FM on d 4 and 7, and greater (P ≤ 0.04) for FM vs. CON on d 1 and 4. Plasma hapto-globin concentrations were greater (P ≤0.01) for TRANS vs. CON and FM on d 1 and 4 and greater (P ≤ 0.05) for FM vs. CON on d 1 and 4. In conclusion, flunixin meglumine reduced the Cortisol and acute-phase protein responses elicited by road transport but did not improve receiving performance of feeder cattle. [ABSTRACT FROM AUTHOR]

A 2-yr study utilizing 120 mature, crossbred (Angus x Herford) cows/year, evaluated the influence of cow BCS and dried distillers grains with solubles (DDGS) supplementation during late gestation on cow performance and productivity of subsequent offspring. Treatments were arranged as a 2 x 2 facto-rial in a randomized complete block design with 2 BCS and with or without DDGS supplementation. Cows were nutritionally managed to enter the last trimester of gestation with a BCS of approximately 4 (LBCS) or 6 (HBCS) and were thereafter managed in a single herd (initial BCS were 4.4 and 5.7 for LBCS and HBCS treatments, respectively). During the last trimester, 12.7 kg/cow of low quality meadow hay (6.4% CP; DM basis) was provided each day. Supplemented cows were gathered and sorted into pens (12 pens; 5 cows/pen; 6 pens/BCS) every Monday, Wednesday, and Friday, and received the equivalent of 0.9 kg/cow daily of DDGS (31% CP; DM basis; supplement was consumed within 30 min on each supplementation day). Calf birth weight was greater for HBCS compared to LBCS (P = 0.001) and for supplemented compared to nonsupplemented cows (P = 0.04). Cow weight at weaning was greater for HBCS compared with LBCS (P < 0.001); however, no differences were noted because of supplementation (P = 0.16). Weaning weight was greater for the offspring of supplemented compared to nonsupplemented cows (P = 0.02). There were no differences in postweaning calf performance (growing lot and feedlot) or carcass char-acteristics (P > 0.05) due to treatments. Nevertheless, HBCS cows had approximately 10% more live calves at birth and at weaning (P < 0.01) compared to LBCS cows. Consequently, the total weaned calf weight per cow was 26 kg greater for HBCS compared with LBCS (P = 0.004). Pregnancy rate was greater (P = 0.05) for HBCS than LBCS cows (92% vs. 79%, respectively) but not affected by supplementation (P = 0.94). This research demonstrates the potential consequences of not maintaining cows in adequate BCS at calving. Also, though it appears that supplementation of beef cows with DDGS during late gestation has a positive effect on weaning weight, there was no apparent develop-mental programming effect on feedlot performance and carcass characteristics of calves. [ABSTRACT FROM AUTHOR]

This experiment compared growth, body composition, plasma IGF-I and leptin, and reproductive development of beef heifers receiving or not recombinant bovine ST (BST) beginning after weaning until the first breeding season. Fifty Angus x Hereford heifers (initial BW = 219 ± 2 kg; initial age = 208 ± 2 d), weaned at approximately 6 mo of age, were assigned to the experiment (d 0 to 210). On d 0, heifers were ranked by initial BW and age and assigned to 1) treatment with BST or 2) saline control. Heifers assigned to the BST treatment received subcutaneous (s.c.) injections containing 250 mg of sometribove zinc whereas control heifers received a 5-mL s.c. injection of 0.9% saline every 14 d. Treatments were initiated on d 14 and last administered on d 196. Heifers were maintained on separate pastures harvested for hay the previous summer according to treatment and received grass and alfalfa hay at a rate to provide a daily amount of 7.0 and 1.0 kg of DM per heifer, respectively. Heifer shrunk BW was collected on d 1 and 211 for heifer ADG calculation. Blood samples were collected weekly from d 0 to 210 for determination of plasma progesterone to estimate puberty attainment as well as plasma concentrations of IGF-I and leptin in selected samples. On d 0, 63, 133, and 189, heifers were evaluated for intramuscular marbling, LM depth, and backfat thickness via real-time ultrasonography. No treatment effects were detected (P = 0.27) for heifer ADG (0.49 vs. 0.51 kg/d for control and BST heifers, respectively; SEM = 0.02). Mean backfat thickness was lesser (P < 0.01) in BST heifers compared with control cohorts (3.56 vs. 3.92 mm, respectively; SEM = 0.08). Heifers receiving BST had greater plasma IGF-I concentrations compared with control cohorts 7 d after treatment administration (treatment x day interaction; P < 0.01). Mean plasma leptin concentrations were lesser (P = 0.05) in BST heifers compared with control cohorts (1.82 vs. 2.03 ng/mL, respectively; SEM = 0.07). Onset of puberty was hastened in BST heifers compared with control cohorts (treatment x day interaction; P = 0.04). In summary, a greater proportion of BST heifers reached puberty during the experiment compared with control cohorts, despite lesser plasma leptin concentrations, backfat thickness, and similar ADG. Hence, circulating IGF-I was positively associated with hastened puberty attainment independently of growth rate, circulating leptin concentrations, and body fat content of replacement beef heifers. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the effects of 24-h road transport or 24-h feed and water deprivation on acute-phase and performance responses of feeder cattle. Angus * Hereford steers (n = 30) and heifers (n = 15) were ranked by gender and BW (217 ± 3 kg initial BW; 185 ± 2 d initial age) and randomly assigned to 15 pens on d -12 of the experiment (3 animals/pen; 2 steers and 1 heifer). Cattle were fed alfalfa-grass hay ad libitum and 2.3 kg/animal daily (DM basis) of a corn-based concentrate throughout the experiment (d -12 to 28). On d 0, pens were randomly assigned to 1 of 3 treatments: 1) transport for 24 h in a livestock trailer for 1,200 km (TRANS), 2) no transport but feed and water deprivation for 24 h (REST), or 3) no transport and full access to feed and water (CON). Treatments were concurrently applied from d 0 to d 1. Total DMI was evaluated daily from d -12 to d 28. Full BW was recorded before treatment application (d -1 and 0) and at the end of experiment (d 28 and 29). Blood samples were collected on d 0, 1, 4, 7, 10, 14, 21, and 28. Mean ADG was greater (P < 0.01) in CON vs. TRANS and REST cattle but similar {P = 0.46) between TRANS and REST cattle (1.27, 0.91, and 0.97 kg/d, respectively; SEM = 0.05). No treatment effects were detected for DMI (P > 0.25), but CON had greater G:F vs. TRANS (P <0.01) and REST cattle (P = 0.08) whereas G:F was similar (P = 0.21) between TRANS and REST cattle. Plasma Cortisol concentrations were greater (P < 0.05) in REST vs. CON and TRANS cattle on d 1,7, 14, and 28 and also greater (P = 0.02) in TRANS vs. CON cattle on d 1. Serum NEFA concentrations were greater (P < 0.01) in REST and TRANS vs. CON cattle on d 1 and greater (P < 0.01) in REST vs. TRANS cattle on d 1. Plasma ceruloplasmin concentrations were greater (P = 0.04) in TRANS vs. CON cattle on d 1, greater (P = 0.05) in REST vs. CON on d 4, and greater (P < 0.05) in REST vs. TRANS and CON on d 14. Plasma haptoglobin concentrations were greater (P < 0.01) in TRANS vs. CON and REST cattle on d 1 and greater (P < 0.05) for REST vs. TRANS and CON cattle on d 7. In conclusion, 24-h transport and 24-h nutrient deprivation elicited acute-phase protein reactions and similarly reduced feedlot receiving performance of feeder cattle. These results suggest that feed and water deprivation are major contributors to the acute-phase response and reduced feedlot receiving performance detected in feeder cattle transported for long distances. [ABSTRACT FROM AUTHOR]

Two experiments evaluated the effects of temperament and acclimation to handling on performance of Angus x Hereford feeder cattle reared in extensive rangeland systems until weaning. In Exp. 1, 200 calves (n = 97 for yr 1; n = 103 for yr 2) were evaluated for temperament at weaning (average age ± SE = 152 ± 1 d) by chute score and exit velocity. Chute score was assessed on a 5-point scale according to behavior during chute restraining. Exit score was calculated by dividing exit velocity into quintiles and assigning calves a score from 1 (slowest) to 5 (fastest). A temperament score was calculated for each calf by averaging chute and exit scores. Calf temperament was classified according to temperament score as adequate (<3) or excitable (>3). After weaning, calves were assigned to a 40-d preconditioning followed by growing (139 d) and finishing (117 d) phases until slaughter. Weaning BW was decreased (P = 0.04) in excitable calves compared with adequate calves. No differences were detected (P >0.21) for ADG during preconditioning, growing, and finishing phases; hence, excitable calves tended (P = 0.09) to have decreased HCW compared with adequate calves. In Exp. 2, 60 steers (initial age ± SE = 198 ± 2 d) were weighed and evaluated for temperament score 35 d after weaning (d-29). On d-28, steers were ranked by these variables and assigned to receive an acclimation treatment or not (control). Acclimated steers were processed through a handling facility twice weekly for 4 wk (d -28 to -1) whereas control steers remained undisturbed on pasture. On d 0, all steers were transported for 24 h and returned to the research facility (d 1). On arrival, steers were ranked by BW within treatment and randomly assigned to 20 feedlot pens for a 28-d feedlot receiving period. Acclimated steers had decreased temperament score and plasma Cortisol compared with controls on d 0 (P = 0.02). During feedlot receiving, acclimated steers had decreased ADG (P <0.01) and G:F (P = 0.03) and tended to have decreased DMI (P = 0.07) compared with controls. Acclimated steers had greater plasma haptoglobin on d 4 (P = 0.04) and greater ceruloplasmin from d 0 to 10 (P < 0.04) and tended to have greater Cortisol on d 1 {P = 0.08) than controls. In conclusion, temperament affects productivity of beef operations based on Bos taurus feeder cattle reared in extensive rangeland systems until weaning whereas acclimation to handling ameliorated cattle temperament but did not benefit feedlot receiving performance. [ABSTRACT FROM AUTHOR]

Three experiments compared ruminal, physiological, and performance responses of beef steers consuming hay ad libitum and receiving grain-based sup-plements without (control) or with (CAM) the inclusion of camelina meal. In Exp. 1, 9 steers fitted with ruminal cannulas received CAM (2.04 kg of DM/d; n = 5) or con-trol (2.20 kg of DM/d; n = 4). Steers receiving CAM had reduced (P = 0.01) total DMI and tended to have reduced (P = 0.10) forage DMI compared with control. No treat-ment effects were detected (P > 0.35) for ruminal hay degradability parameters. In Exp. 2, 14 steers fed CAM (1.52 kg of DM/d; n = 7) or control (1.65 kg of DM/d; n = 7) were assigned to a corticotropin-releasing hormone (CRH; 0.1 pg/kg of BW) and a thyrotropin-releasing hormone (TRH; 0.33 pg/kg of BW) challenge. Steers fed CAM had greater (P < 0.05) serum concentrations of PUFA compared with control before challenges. Upon CRH infusion, plasma haptoglobin concentrations tend-ed (P = 0.10) to be reduced and ceruloplasmin concentra-tions increased at a lesser rate in CAM steers compared with control (treatment x time; P < 0.01). Upon TRH infusion, no treatment effects were detected (P > 0.55) for serum thyrotropin-stimulating hormone, triiodothyro-nine, and thyroxine. In Exp. 3,60 steers were allocated to 20 pens. Pens were assigned randomly to receive CAM (2.04 kg of DM/steer daily; n = 10) or control (2.20 kg of DM/steer daily; n = 10) during preconditioning (PC; d -28 to 0). On d 0, steers were transported for 24 h. Upon arrival, pens were assigned randomly to receive CAM or control during feedlot receiving (FR; d 1 to 29). During PC, CAM steers had reduced (P <0.01) forage and total DMI, and tended to have reduced (P = 0.10) ADG com-pared with control. Plasma linolenic acid concentrations increased during PC for CAM steers, but not for control (treatment x day; P = 0.02). During FR, steers fed CAM during PC had reduced (P <0.01) forage and total DMI, but tended (P = 0.10) to have greater G:F compared with control. Steers fed CAM during FR had greater (P < 0.05) plasma concentrations of PUFA, and reduced rectal temperature and concentrations of haptoglobin and ceru-loplasmin during FR compared with control. In summa-ry, CAM supplementation to steers impaired forage and total DMI, did not alter thyroid gland function, increased circulating concentrations of PUFA, and lessened the acute-phase protein reaction elicited by neuroendocrine stress responses. [ABSTRACT FROM AUTHOR]

Two experiments evaluated the effects of temperament and acclimation to handling on reproduc-tive performance of Bos taurus beef females. In Exp. 1, 433 muciparous, lactating Angus x Hereford cows were sampled for blood and evaluated for temperament before the breeding season. Cow temperament was assessed by chute score and exit velocity. Chute score was assessed on a 5-point scale according to behavioral responses during chute restraining. Exit score was calculated by dividing exit velocity into quintiles and assigning cows with a score from 1 to 5 (1 = slowest, 5 = fastest cows). Temperament score was calculated by averaging chute and exit scores. Cows were classified for temperament type according to temperament score (< 3 = adequate, ≤ 3 = aggressive). Plasma Cortisol concentrations were greater (P <0.01) in cows with aggressive vs. adequate temperament. Cows with aggressive temperament had reduced (P ≤0.05) pregnancy and calving rate and tended to have reduced (P = 0.09) weaning rate compared with cows with adequate temperament. Hence, kilogram of calf bom per cow was reduced (P = 0.05) and kilogram of calf weaned per cow tended to be reduced (P=0.08) in aggressive cows. In Exp. 2, 88 Angus x Hereford heifers (initial age = 206 ± 2 d) were weighed (d 0 and 10) and evaluated for temperament score (d 10). On d 11, heifers were ranked by these variables and assigned to receive or not (control) an acclimation treatment. Acclimated heif-ers were processed through a handling facility 3 times weekly for 4 wk (d 11 to 39; Mondays, Wednesdays, and Fridays), whereas control heifers remained undisturbed on pasture. Heifer puberty status, evaluated via plasma progesterone concentrations, was assessed on d 0 and 10, d 40 and 50, 70 and 80, 100 and 110, 130 and 140, 160 and 170, and 190 and 200. Blood samples collected on d 10 and 40 were also analyzed for plasma concentra-tions of Cortisol and haptoglobin. Temperament score was assessed again on d 40 and d 200. Acclimated heif-ers had reduced (P = 0.01) concentrations of Cortisol and haptoglobin on d 40 and reduced (P = 0.02) exit veloc-ity on d 200 compared with control heifers. Puberty was hastened in acclimated heifers compared with control (P = 0.01). Results from this study indicate that B. taurus beef cows with aggressive temperament have impaired reproductive performance compared with cohorts with adequate temperament, whereas acclimation to human handling after weaning hastens reproductive develop-ment of replacement heifers. [ABSTRACT FROM AUTHOR]

Three experiments were conducted to evaluate plasma concentrations of glucose, insulin, IGF-I, and progesterone (P4) in pubertal beef heifers receiv-ing exogenous glucose, insulin, or sometribove zinc. All heifers used had no luteal P4 synthesis but received a controlled internal drug-releasing device containing 1.38 g of P4 to estimate treatment effects on hepatic P4 degradation. In Exp. 1, 8 pubertal, nulliparous Angus x Hereford heifers (initial BW = 442 ± 14 kg; initial age = 656 ± 7 d) were randomly assigned to receive, in a crossover design containing 2 periods of 10 h, intrave-nous (i.v.) infusions (10 mL) of insulin (1 pg/kg of BW; INS) or saline (0.9%; SAL). Treatments were adminis-tered via jugular venipuncture in 7 applications (0.15 pg insulin/kg BW per application) 45 min apart (from 0 to 270 min). Blood samples were collected immediately before each infusion as well as at -120, -60, 330, 390, and 450 min relative to the first infusion. Heifers receiv-ing INS had greater (P < 0.01) plasma insulin, reduced (P < 0.04) plasma glucose and IGF-I, and similar (P = 0.62) plasma P4 concentrations compared with SAL heifers. In Exp. 2, the same heifers were assigned to receive, in a similar experimental design as Exp. 1, i.v. infusions (10 mL) of 1) insulin (1 pg/kg BW) and glucose (0.5 g/kg BW; INS+G) or 2) SAL. Heifers receiving INS+G had greater (P < 0.02) plasma insulin, glucose, and P4 but reduced (P = 0.01) plasma IGF-I concentrations com-pared with SAL heifers. In Exp. 3, the same heifers were assigned to receive, in a crossover design containing 2 periods of 14 d, subcutaneous (s.c.) injections of 1) 250 mg of sometribove zinc (BST) or 2) SAL. Blood samples were collected 3 h apart (0900, 1200, 1500, and 1800 h) from heifers on d 6, 8, and 10 relative to treatment administration (d 1). Heifers receiving BST had greater (P <0.01) plasma glucose and IGF-I and similar (P > 0.67) plasma insulin and P4 concentrations compared with SAL heifers. Results from this series of experiments suggested that concun-ent increases in glucose and insu-lin are required to reduce hepatic catabolism and increase plasma concentrations of P4 in bovine females. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare performance, physiological, and reproductive responses of beef heifers consuming forages differing in nutritional quality and offered a low-starch energy supplement at 2 different frequencies. Forty-eight Brahman x British heifers (initial age = 294 ± 3 d) were allocated into 1 of 16 drylot pens (3 heifers/pen) which were randomly assigned to receive, in a 2 x 2 factorial arrangement of treatments: 1) low-quality hay [LQ; stargrass {Cynodon nlemfuensis) with 8% CP and 81 % NDF, DM basis] and daily supplementation (S7); 2) LQ and supplementation 3 times weekly (S3); 3) medium-quality hay [MQ; bermudagrass (C dactylon) with 12% CP and 74% NDF, DM basis] and S7; and 4) MQ and S3. Throughout the study (d 0 to 120), hay was offered in amounts to ensure ad libitum access, and a supplement based on soybean hulls and wheat middlings was offered at weekly rates of 15.8 and 7.9 kg/heifer (DM basis) for LQ and MQ, respectively. Forage and total DMI were evaluated daily, from d 20 to 26, d 34 to 40, and d 48 to 54. Blood samples were collected weekly for determination of plasma progesterone to evaluate puberty attainment. Blood samples were also collected daily, from d 13 to 16, d 27 to 30, d 41 to 44, and d 55 to 58 for determination of plasma urea nitrogen (PUN), glucose, insulin, IGF-I, and NEFA. On d 60, heifers were reallocated by treatment into 4 paddocks and exposed to Angus bulls (1:12 bulhheifer ratio) until d 120. Date of conception was estimated retrospectively by subtracting gestation length (286 d) from the calving date. Heifers receiving S7 had similar (P = 0.52) ADG compared with S3 heifers (0.27 vs. 0.25 kg/d). Heifers provided S7 had less daily variation in hay DMI and plasma concentrations of glucose, NEFA, and IGF-I compared with S3 cohorts (supplementation frequency x day interaction; P < 0.01). Similarly, heifers offered MQ and LQ and receiving S7 had less daily variation in total DMI, energy and protein intake, and plasma concentrations of PUN compared with heifers offered MQ and LQ and receiving S3 (hay quality x supplementation frequency x day interaction; P < 0.01). Attainment of puberty and pregnancy were hastened in S7 heifers compared with S3 heifers (supplementation frequency x week interaction; P < 0.02). Therefore, reproductive development of beef replacement heifers consuming diets based on low- and medium-quality forages are enhanced when low-starch energy supplements are offered daily instead of 3 times weekly. [ABSTRACT FROM AUTHOR]

The objective was to compare the acute-phase response of steers receiving different doses of bovine corticotropin-releasing hormone (CRH). Fourteen weaned Angus steers (BW = 191 ±2.1 kg, age = 167 ± 4.7 d) fitted with an indwelling jugular catheter and a rectal temperature (RT) monitoring device were assigned to receive 1 of 3 treatments (intravenous infusion): 1) 0.1 &mgr;g of CRH/kg of BW (CRH1; n = 5), 2) 0.5 ug of CRH/kg of BW (CRH5; n = 5), and 3) 10 mL of saline (0.9%; n = 4). Blood samples were collected via catheters, relative to treatment infusion (0 h), hourly from -2 to 0 h and 4 to 8 h and every 30 min from 0 to 4 h. Rectal temperatures were recorded every 30 min from -2 to 8 h. Blood samples were also collected via jugular venipuncture and rectal temperatures assessed using a digital thermometer every 6 h from 12 to 72 h and every 24 h from 96 to 168 h. All plasma samples collected during the study were analyzed for concentrations of haptoglobin. All plasma samples collected from -2 to 8 h were analyzed for Cortisol concentrations. Serum samples collected hourly from -2 to 8 h were analyzed for concentrations of NEFA, IL-6, tumor necrosis factor (TNF)-&agr;, and interferon-&ggr;. Cortisol peaked at 0.5 h for CRH1 steers but returned to baseline concentrations at 1 h relative to infusion (time effect; P < 0.01). In CRH5 steers, Cortisol peaked at 0.5 h and returned to baseline concentrations 3.5 h relative to infusion (time effect; P < 0.01). Cortisol concentrations did not change after treatment infusion for saline steers (time effect; P = 0.42). In CRH1 steers, NEFA concentrations peaked 5 h after treatment infusion (time effect; P = 0.01). Conversely, serum NEFA concentrations did not change for CRH5 and saline steers after treatment infusion (time effect; P > 0.37). Mean serum TNF-&agr; concentrations in CRH1 steers after treatment infusion were greater compared with saline (P = 0.02), tended to be greater (P = 0.08) compared with CRH5, and were similar (P = 0.40) between CRH5 and saline steers. Mean RT in CRH1 steers after treatment infusion were greater (P < 0.04) compared with saline and CRH5 and similar (P = 0.50) between CRH5 and saline steers. Haptoglobin increased and peaked 72 h after treatment infusion for CRH1 steers (time effect; P = 0.01) but did not change for CRH5 and saline steers (time effect; P > 0.45). In conclusion, the bovine acute-phase response stimulated by CRH infusion is dependent on the CRH dose and the subsequent response in circulating Cortisol. [ABSTRACT FROM AUTHOR]

An in situ study (Exp. 1) using 4 ruminally cannulated steers (343 ± 11 kg BW) in a completely randomized design was used to compare ruminal degradation characteristics of low-quality cool-season (C3; Kentucky bluegrass straw; Poa pratensis; 6.3% CP; DM basis) and warm-season (C4; tallgrass prairie; 5.7% CP; DM basis) forage. Four ruminally cannulated steers (252 ± 8 kg BW; Exp. 2) and 4 wethers (38 ± 1 kg BW; Exp. 3) were used in two, 2 × 2 factorial design experiments to determine the influence of supplemental CP (CPSupp; soybean meal; 0.09 and 0.19% BW, CP basis, for steers and lambs respectively) on nutrient intake and digestion of C3 and C4 forages. Steers and wethers were allotted to separate 4 × 4 Latin squares that ran simultaneously with 20-d periods. In Exp. 1, C3 had greater A fractions (fraction of total pool disappearing at a rate too rapid to measure) and effective degradability of DM and NDF compared with C4 (P < 0.01). Also, C3 had a greater (P < 0.01) A fraction and effective degradability of N while the C fraction (fraction of total pool unavailable in the rumen) was less (P < 0.01) compared with C4. Consequently, rumen degradable protein accounted for 84.7% of total CP in C3 as compared to 66% for C4 (P < 0.01). In Exp. 2, a CPSupp × forage interaction (P < 0.01) was noted for forage and total DMI, with CPSupp increasing intake of C4 by 47%, and C3 forage by only 7%. Dry matter digestibility responded similarly with a CPSupp × forage interaction (P = 0.05; CPSupp increased digestibility 21% with C4 and 9% with C3 forage). Also, CPSupp × forage interactions were noted for ruminal liquid retention time (P = 0.02; CPSupp decreased retention 3.6 h with C4 and only 0.6 h with C3 forage) and particulate passage rate (P = 0.02; CPSupp increased passage 46% with C4 and 10% with C3 forage). As in Exp. 2, a CPSupp × forage interaction (P = 0.01; CPSupp increased digestibility 18% with C4 and 7% with C3 forage) was observed with DM digestibility in Exp. 3. In contrast, only N balance (P < 0.01) and N digestibility (P < 0.01) were affected by CPSupp. These data suggest that intake and digestion of low-quality C3 and C4 forages by ruminants are not similar and, more importantly, the physiological response of ruminants to protein supplementation of low-quality forage is dependent on forage type. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to compare ruminal, physiological, and performance responses of forage-fed cattle consuming grain-based supplements without (NF) or with the inclusion (10%; DM basis) of a rumen-protected PUFA (PF) or SFA source (SF). Supplements were offered and consumed at 0.6% of BW/animal daily (DM basis). In Exp. 1, DMI and ruminal in situ forage degradability were evaluated in 3 Angus × Hereford cows fitted with ruminal cannulas and allocated to a 3 x 3 Latin square design. Within each experimental period, hay was offered in amounts to ensure ad libitum access from d 1 to 13, DMI was recorded from d 8 to 13, and cows were limited to receive 90% of their average hay DMI (d 1 to 13) from d 14 to d 21. On d 16, polyester bags containing 4 g of ground hay (DM basis) were incubated within the rumen of each cow for 0, 4, 8, 12, 24, 36, 48, 72, and 96 h. Hay and total DMI were reduced (P < 0.05) in PF cows compared with SF and NF cows. No treatment effects were detected (P > 0.48) for ruminal disappearance rate and effective ruminal degradability of hay DM and NDF. In Exp. 2, preconditioning DMI, ADG, carcass traits, and plasma concentrations of cortisol, FA, acute-phase proteins, and pro-inflammatory cytokines were assessed in 72 Angus × Hereford steers receiving supplement treatments during a 28-d preconditioning period. All steers were transported to a commercial growing lot after preconditioning (d 1), and later moved to an adjacent commercial finishing yard (d 144) where they remained until slaughter. No treatment effects were detected (P = 0.52) for preconditioning ADG and G:F, but DMI tended (P = 0.09) to be reduced in PF steers compared with NF and SF. Plasma PUFA concentrations were greater in PF steers compared with NF and SF (P = 0.01). Following transportation, concentration of tumor necrosis factor-a increased for NF, did not change for SF, but decreased for PF steers (treatment × day interaction, P < 0.01). Steers fed PF had greater (P = 0.02) ADG compared with NF steers during the growing phase. Carcass yield grade and marbling were greater (P < 0.05) for PF compared with NF steers. In conclusion, PUFA supplementation did not impact ruminal forage degradability, but impaired DMI in beef cows. Further, PUFA supplementation to steers during preconditioning reduced plasma concentrations of TNF-a following transportation, and benefited growing lot ADG and carcass marbling. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate plasma concentrations of cortisol, acutephase proteins, and proinflammatory cytokines in beef steers after an intravenous corticotrophin-release hormone (CRH) infusion. Six weaned, halter-trained Angus steers (BW = 163 ± 7.0 kg; age = 203 ± 5.8 d) were fitted with indwelling jugular catheters on d -1 of the study and assigned to receive intravenously 0.1 μg of bovine CRH/kg of BW on d 0 of the study. Blood samples were collected every hour via jugular catheters from -1 to 8 h, and every 6 h via jugular venipuncture from 12 to 72 h relative to CRH infusion (0 h). Steer rectal temperature was assessed concurrently with each blood collection. Samples collected from -1 to 8 h relative to CRH infusion were analyzed for plasma concentrations of IL-1β and IL-6, tumor necrosis factor-α, interferon-γ, cortisol, ceruloplasmin, and haptoglobin, whereas samples collected from 12 to 72 h were analyzed for plasma concentrations of ceruloplasmin and haptoglobin only. Plasma cortisol concentrations were greater (P < 0.01) at 1, 2, and 3 h compared with prechallenge values (2.8, 2.3, 13.9, 8.2, and 5.7 ng/mL for -1, 0, 1, 2, and 3 h, respectively; SEM = 0.6). Mean postchallenge IL-6 concentrations were greater (P = 0.04) compared with mean prechallenge values (1.49 vs. 1.34 log pg/mL; SEM = 0.05), whereas IL-6 concentrations at 6 h were greater (P ≤ 0.05) compared with prechallenge values (1.36, 1.33, and 1.61 log pg/mL at -1, 0, and 6 h, respectively; SEM = 0.09). Rectal temperatures were greater (P < 0.01) at 2 and 8 h compared with prechallenge values (38.9, 39.0, 39.3, and 39.5°C at -1, 0, 2, and 8 h, respectively; SEM = 0.07). Plasma ceruloplasmin concentrations were greater (P = 0.03) at 54 h (29.6, 31.5, and 35.2 mg/dL at -1, 0, and 54 h, respectively; SEM = 1.7), whereas plasma haptoglobin concentrations were greater (P < 0.05) at 54, 66, and 72 h compared with prechallenge values (3.3, 2.8, 4.3, 4.6, and 4.1 absorbance at 450 nm × 100 at -1, 0, 54, 66, and 72 h, respectively; SEM = 0.24). In conclusion, intravenous CRH infusion at 0.1 μg/kg of BW increased circulating concentrations of cortisol and stimulated the acute-phase response in halter-trained beef steers. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to evaluate the influence of a yeast-derived cell wall preparation (YCW) on forage intake and digestibility, ruminal fermentation characteristics, serum prolactin and prolactin stores, and milk production in beef cattle consuming high-alkaloid tall fescue straw. In Exp. 1, 16 ruminally cannulated Angus × Hereford steers (200 ± 6 kg of BW) were blocked by BW and within block were assigned to I of 4 treatments containing YCW at 0, 20, 40, or 60 g/d. Tall fescue straw (579 μg of ergovaline/kg of DM) was provided at 120% of the previous 5-d average intake, with soybean meal used as a CP supplement. In the 29-d digestion study, total DM, OM, and NDF intakes and DM, OM, and NDF digestibilities were not affected by YCW supplementation (P > 0.13). Linear decreases in ruminal indigestible ADF outflow (P = 0.10) and liquid dilution rate (P = 0.03) were noted as YCW increased. Weekly serum prolactin was not affected by treatment (P > 0.50), but prolactin stores increased linearly as YCW increased (P = 0.05). In Exp. 2, 60 Angus × Hereford cows (517 ± 5 kg of BW; approximately 200 d of gestation) were stratified by BCS (5.0 ± 0.1) and randomly assigned to the same 4 YCW treatments as in Exp. 1 (447 μg of ergovaline/kg of DM, high-alkaloid straw), but with the addition of a low-alkaloid straw (149 μg of ergovaline/kg of DM; no YCW supplementation) as a control. Cows were provided ad libitum access to straw, and diets were supplemented with soybean meal daily. One cow was removed from the 40 g/d treatment because of clinical signs of fescue foot. No differences (P > 0.20) were observed in pre- or postcalving BCS change or postcalving BW change. Control cows gained more BW (P = 0.02) precalving compared with cows given 0 g/d of YCW. A linear increase (P = 0.04) in milk production at 60 d postpartum was observed as YCW increased. Serum prolactin postcalving and the change from initial to postcalving increased linearly (P = 0.02 and P = 0.06, respectively) with increasing YCW supplementation. In addition, postcalving serum prolactin was less for 0 g/d of YCW compared with the control (P = 0.003) and 20 g/d of YCW (P = 0.04). The YCW seemed to alleviate the prolactin depression normally associated with fescue toxicosis and therefore has the potential to be used successfully with other management practices when feeding or grazing high-alkaloid tall fescue. [ABSTRACT FROM AUTHOR]

The objectives of this research were to determine the influence of protein supplementation frequency on cow performance, grazing time, distance traveled, maximum distance from water, cow distribution, DMI, DM digestibility, harvest efficiency, percent- age of supplementation events frequented, and CV for supplement intake for cows grazing low-quality forage. One hundred twenty pregnant (60 ± 45 d) Angus × Hereford cows (467 ± 4 kg BW) were used in a 3 × 3 Latin square design for one 84-d period in each of three consecutive years. Cows were stratified by age, BCS, and BW and assigned randomly to one of three 810- ha pastures. Treatments included an unsupplemented control (CON) and supplementation every day (D; 0.91 kg, DM basis) or once every 6 d (GD; 5.46 kg, DM basis) with cottonseed meal (CSM; 43% CP, DM basis). Four cows from each treatment (each year) were fitted with global positioning system collars to estimate grazing time, distance traveled, maximum distance from water, cow distribution, and percentage of supplementation events frequented. Collared cows were dosed with intraruminal n-alkane controlled-release devices on d 28 for estimation of DMI, DM digestibility, and harvest efficiency. Additionally, Cr2O3 was incorporated into CSM on d 36 at 3% of DM for use as a digesta flow marker to estimate the CV for supplement intake. Cow BW and BCS change were greater (P ⩽ 0.03) for supplemented treatments compared with CON. No BW or BCS differences (P ⩾ 0.14) were noted between D and 6D. Grazing time was greater (P = 0.04) for CON compared with supplemented treatments, with no difference (P = 0.26) due to supplementation frequency. Distance traveled, maximum distance from water, cow distribution, DMI, DM digestibility, and harvest efficiency were not affected (P ⩾ 0.16) by protein supplementation or supplementation frequency. The percentage of supplementation events frequented and the CV for supplement intake were not affected (P ⩾ 0.58) by supplementation frequency. Results suggest that providing protein daily or once every 6 d to cows grazing low-quality forage increases BW and BCS gain, while decreasing grazing time. Additionally, protein supplementation and supplementation frequency may have little to no effect on cow distribution, DMI, and harvest efficiency in the northern Great Basin. [ABSTRACT FROM AUTHOR]

Two experiments were conducted to determine the influence of supplemental nonprotein N (NPN) provided daily (D) or every other day (2D) on ruminant performance and N efficiency. Treatments included an unsupplemented control (CON) and a urea (28.7% CP) or biuret (28.6% CP) supplement provided D or 2D at 0700. In Exp. 1, five weathers (39 ± 1 kg BW) were used in an incomplete 5 × 4 Latin square with four 24-d periods to determine the influence of supplemental NPN source and supplementation frequency (SF) on the efficiency of N use in lambs consuming low-quality grass straw (4% CP). The amount of CP supplied by each supplement was approximately 0.10% of BW/d (averaged over a 2-d period). In Exp. 2, 80 Angus × Hereford cows (540 ± 8 kg BW) in the last third of gestation were used to determine the effect of NPN source and SF on cow performance. The NFN treatments were formulated to provide 90% of the estimated degradable intake protein requirement. The supplemented treatments received the same amount of supplemental N over a 2-d period; therefore, the 2D treatments received double the quantity of supplemental N on their respective supplementation day than the D treatments. In Exp. 1, total DM, OM, and N intake; DM, OM, and N digestibility; N balance; and digested N retained were greater (P < 0.03) for supplemented than for CON weathers, with no difference (P > 0.05) between NPN sources or SF. Plasma urea-N (PUN) was increased with N supplementation compared with CON (P < 0.01), and urea treatments had greater PUN than biuret (P < 0.01). In addition, PUN was greater (P = 0.02) for D than for 2D treatments. In Exp. 2, pre- and postcalving (within 14 d and 24 h after calving, respectively) cow weight and body condition score change were more positive (P < 0.05) for supplemented groups than for CON. These results suggest that supplements containing urea or biuret as the primary source of supplemental N can be effectively used by lambs and cows consuming low-quality forage, even when provided every other day. [ABSTRACT FROM AUTHOR]

Five ruminally and duodenally cannulated steers (491 ± 21 kg BW) were used in an incomplete 5 × 4 Latin square with four 24-d periods to determine the influence of supplemental nonprotein N (NPN) source and supplementation frequency (SF) on the dynamics of ruminal fermentation in steers consuming low-quality grass straw (4% CP). Treatments (TRT) included an unsupplemented control (CON) and a urea or biuret supplement that were placed directly into the rumen at 0700 dally (D) or every other day (2D). The NPN treatments were formulated to provide 90% of the estimated degradable intake protein requirement; therefore, the urea and biuret treatments received the same amount of supplemental N over a 2-d period. Daily TRT were supplemented with CP at 0.04% of BW/d, whereas the 2D TRT were supplemented at 0.08% of BW every other day. Forage was provided at 120% of the previous 5-d average intake in two equal portions at 0715 and 1900. Ruminal fluid was collected 0, 3, 6, 9, 12, and 24 h after supplementation on a day of and a day before supplementation for all TRT. Ruminal NH3-N increased (P < 0.04) with CP supplementation on the day all supplements were provided and on the day on which only daily supplements were provided compared with the CON. However, an NPN source × SF interaction (P = 0.03) on the day all supplements were provided indicated that NH3-N increased at a greater rate for urea as SF decreased compared with biuret. Ruminal NHa-N on the day only daily supplements were provided was greater (P = 0.02) for D compared with 2D. On the day all supplements were provided, D increased (P = 0.05) ruminal indigestible acid detergent fiber passage rate and ruminal fluid volume compared with 2D. These results suggest that urea or biuret can be used effectively as a supplemental N source by steers consuming low-quality forage without adversely affecting ruminal fermentation, even when provided every other day. [ABSTRACT FROM AUTHOR]

Five steers (491 ± 21 kg BW) were used in an incomplete 5 × 4 Latin square with four 24-d periods to determine the influence of supplemental nonprotein N (NPN) source and supplementation frequency (SF) on nutrient intake and site of digestion in steers consuming low-quality grass straw (4% CP). Treatments (TRT) included an unsupplemented control and a urea- or biuret-containing supplement placed directly into the rumen daily (D) or every other day (2D) at 0700. The NPN treatments were formulated to provide 90% of the estimated degradable intake protein requirement. Daily TRT were supplemented CP at 0.04% of BW/d, whereas the 2D TRT were supplemented at 0.08% of BW every other day. Therefore, all supplemented TRT received the same quantity of supplemental CP over a 2-d period. Forage OM intake was not affected (P > 0.05) by NPN supplementation, NPN source, or SF; however, total OM and N intake were increased (P < 0.01) with CP supplementation. Duodenal flow of N was greater (P = 0.04) with CP supplementation compared with the control. In addition, duodenal bacterial N flow was increased with CP supplementation (P = 0.04) and for biuret compared with urea (P < 0.01). Bacterial efficiency (g bacterial N/kg OM truly digested in the rumen) was greater (P = 0.05) for biuret than for urea. Apparent total-tract N digestibility was increased with NPN supplementation (P < 0.01) but not affected by NPN source or SF. These results suggest that urea or biuret can be used effectively as a supplemental N source by steers consuming low-quality forage. [ABSTRACT FROM AUTHOR]

Presents a study which evaluated the effect of small intestinal carbohydrate on sodium-glucose cotransport in brush border membrane vesicles prepared from different equidistant sites along the small intestine in cattle. Details on brush-border membrane preparation; Overview of sodium-glucose cotransport activity and kinetics; Changes in alkaline phosphatase and maltase activities in the intestine.

Presents information on an experiment which evaluated the effect of the ionophore laidlomycin propionate on steer performance and ruminal nitrogen metabolism. Ruminal characteristics; Experimental procedure; Results and discussion.

Presents information on a study which evaluated the effect of supplemental poultry by-product meal (PBM) on the duodenal flow and small intestinal disappearance of amino acids in steer calves consuming a corn silage- and cottonseed hull-based diet. Materials and methods used on the study; Results and discussions.

Presents information on a study that evaluated poultry by-product meal (PBM) as a supplemental nitrogen (N) source for ruminants. Comparison of the solubility, degradation rate and ruminal escape of PBM N with blood meal (BM), corn gluten meal (CGM) and soybean meal (SBM); Methodology used in the study; Statistical analysis; Discussion on the results of the study; Implications of the data gathered.

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 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]