The Professional Animal Scientist最新文献

{"title":"Use of extensive winter feeding systems for backgrounding beef calves and the effect on finishing","authors":"S. McMillan ,&nbsp;G.B. Penner ,&nbsp;J.J. McKinnon ,&nbsp;K. Larson ,&nbsp;F. Añez-Osuna ,&nbsp;D. Damiran ,&nbsp;H.A. (Bart) Lardner","doi":"10.15232/pas.2017-01614","DOIUrl":"10.15232/pas.2017-01614","url":null,"abstract":"<div><p>The introduction of low heat unit corn varieties in western Canada has led to questions on how this crop might fit into an extensive backgrounding program. Therefore, a 3-yr study was conducted to evaluate the effects of grazing standing whole-plant corn (<span><em>Zea mays</em></span> L. ‘Pioneer P7443R’) or swathed whole-plant barley (<span><em>Hordeum vulgare</em></span><span> ‘Ranger’) compared with barley hay fed in drylot pens on beef steer performance during backgrounding and feedlot<span> phases. The effect of backgrounding system was also assessed during finishing when steers were fed diets based on barley grain or corn grain. Each yr, 120 Angus steers (BW = 250.5</span></span> <!-->±<!--> <!-->1.8 kg) were allocated to 1 of 3 replicated (n = 2) backgrounding systems: (1) field grazing swathed whole-plant barley (BSG; 11.2% CP, 60.6% TDN); (2) field grazing standing whole-plant corn (CG; 8.7% CP, 64.6% TDN); or (3) drylot (DL) bunk feeding of processed barley hay (10.9% CP, 57.2% TDN) for an average 78 d (42 to 95 d) trial. All calves received 2.5 kg/d of a range pellet supplement (16% CP, 78% TDN). Treatment groups were similar (<em>P</em> &gt; 0.05) in final BW (295.8<!--> <!-->±<!--> <!-->5.0 kg), ADG (0.59<!--> <!-->±<!--> <!-->0.03 kg/d), and G:F ratio (0.187<!--> <!-->±<!--> <!-->0.03 kg/kg). The cost of gain of DL, BSG, and CG steers was CAN$6.32, CAN$3.14, and CAN$2.96/kg, respectively. Following backgrounding, each replicate group of steers was subdivided and placed in a feedlot for finishing on either a barley- (12.2% CP, 75.4% TDN) or corn grain–based (11.3% CP, 74.7% TDN) diet for an average of 120 d. There were no backgrounding system, finishing, or backgrounding system × finishing interaction effects (<em>P</em><span> &gt; 0.05) for feedlot DMI, ADG, G:F, or carcass characteristics. Study results suggest that grazing either swathed barley or whole-plant corn for 65 d during backgrounding can reduce (</span><em>P</em> = 0.05) costs by CAN$60 and CAN$70/steer, respectively, compared with feeding steers barley hay in a drylot.</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"34 1","pages":"Pages 19-31"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01614","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89630329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Case Study: The effects of photoperiod on feeding behavior of lactating dairy cows in tie-stalls","authors":"K. Macmillan,&nbsp;O.S. Espinoza,&nbsp;M. Oba","doi":"10.15232/pas.2017-01674","DOIUrl":"10.15232/pas.2017-01674","url":null,"abstract":"<div><p>To determine the effects of photoperiod management on behavior of dairy cows, 30 lactating cows were subjected to a long-day (16 h/d light) or short-day photoperiod (8 h/d light). Feeding behavior was observed and feed refusals were collected before and after a 21-d adaptation to photoperiod treatment. Feeding behavior data were summarized for 4 daily time periods based on light schedule, and no effect of light treatment was observed for DMI, lying time, or overall feeding behavior. However, in time period 4 (1600 to 1900 h), the long-day treatment decreased lying time (28.3 vs. 37.7 min/h) and tended to increase eating time (17.5 vs. 9.03 min/h). There was also a tendency for the long-day treatment to reduce daily feed sorting. Providing supplementary light may reduce sorting and increase distribution of eating activities throughout the day, and the change in feeding pattern may be affected by the time of day the supplementary light is provided.</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"34 1","pages":"Pages 103-107"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01674","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81786981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term effect of organic trace minerals on growth, reproductive performance, and first lactation in dairy heifers","authors":"F. Pino ,&nbsp;N.L. Urrutia ,&nbsp;S.L. Gelsinger ,&nbsp;A.M. Gehman ,&nbsp;A.J. Heinrichs PAS","doi":"10.15232/pas.2017-01680","DOIUrl":"10.15232/pas.2017-01680","url":null,"abstract":"<div><p><span>The effect of trace mineral nutrition in utero and during growth and first lactation was evaluated using 64 multiparous dry cows supplemented with organic (OTM) or inorganic trace minerals (ITM) for 60 d before calving. At calving each calf was alternately assigned to OTM or ITM, to obtain 32 calves in each treatment. Calves received OTM or ITM treatments in colostrum<span> (from treatment mothers), milk replacer<span>, and starter, and then as heifers they received treatment in a TMR until 100 DIM. Growth, reproductive, and lactation performances until 100 DIM were evaluated. Age at calving was compared by treatment. Body weight, hip height, withers height, and heart girth were not affected by the trace mineral form received before calving (</span></span></span><em>P</em> &gt; 0.05) except near calving, when these traits were affected by some heifers leaving the study as they calved. Heifers fed OTM tended to calve earlier than those supplemented with ITM (<em>P</em> = 0.07). Overall milk yield until 100 DIM was greater in OTM supplemented heifers (<em>P</em><span><span> = 0.09); however, trace mineral form did not affect milk quality. Overall, in the long term, OTM appeared to improve age at calving and early-lactation milk production of </span>dairy heifers, which may affect their future productive life.</span></p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"34 1","pages":"Pages 51-58"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01680","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90751884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ruminal degradation and intestinal digestibility of camelina meal and carinata meal compared with other protein sources","authors":"R.D. Lawrence,&nbsp;J.L. Anderson","doi":"10.15232/pas.2017-01647","DOIUrl":"10.15232/pas.2017-01647","url":null,"abstract":"<div><p><span>Production of reneweable feedstocks for biodiesel<span><span> have drawn attention to alternative oilseed crops. Our objective was to determine DM and CP ruminal degradability and intestinal digestibility of camelina meal (CAM) and carinata meal (CAR), compared with </span>canola meal<span> (CAN), linseed meal<span><span> (LIN), soybean meal (SBM), and distillers dried grains with solubles (DDGS) as controls. In situ degradability measurements were done using 3 multiparous, mid-late lactation ruminally cannulated </span>Holstein cows. Sample bags were ruminally incubated in duplicate for each cow and feedstuff for 0, 2, 4, 8, and 12 h and in triplicate for 24 and 48 h. Eight bags of each feed were incubated at 12 h for use of the residues in determination of in vitro intestinal digestibility. Ruminal particulate passage rate averaged 6.0%/h. Rate of DM degradation was greatest (</span></span></span></span><em>P</em> &lt; 0.05) for CAM and LIN and least for DDGS, whereas CAR and SBM were similar. Ruminally degradable DM was greatest (<em>P</em> &lt; 0.01) in CAM, CAR, and SBM. The CAM and CAR had the greatest (<em>P</em><span> &lt; 0.05) RDP and least RUP. Intestinal digestible protein was similar (</span><em>P</em> &gt; 0.05) for LIN, CAM, and CAR, which was greater (<em>P</em> &lt; 0.05) than CAN and DDGS. Intestinally absorbable digestible protein was least for CAM and CAR (<em>P</em> &lt; 0.01) compared with the other feeds. Total digestible protein was similar (<em>P</em> &gt; 0.05) for CAM and CAR compared with SBM and LIN. Results indicate that CAM and CAR are highly degradable and comparable to SBM and LIN for protein utilization.</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"34 1","pages":"Pages 10-18"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01647","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83710030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Injectable trace-mineral supplementation improves sperm motility and morphology of young beef bulls1","authors":"G.W. Preedy,&nbsp;S.L. Hill,&nbsp;J.S. Stevenson,&nbsp;R.L. Weaber,&nbsp;K.C. Olson PAS","doi":"10.15232/pas.2017-01667","DOIUrl":"10.15232/pas.2017-01667","url":null,"abstract":"<div><p><span><span><span>This experiment evaluated effects of supplemental s.c. trace-mineral injections on growth and breeding soundness of bull calves. Weaned bulls (n = 488; initial BW = 308 ± 45 kg, initial age = 203 ± 17 d) of 2 breeds (Angus and Charolais) and originating from 13 ranches in the Great Plains were transported to a common confinement facility and assigned randomly to 2 treatments: (1) s.c. injections of trace mineral (TM) containing 15 mg/mL Cu, 5 mg/mL Se, 10 mg/mL Mn, and 60 mg/mL Zn or (2) s.c. injections of physiological saline (control). Treatments were administered at arrival (d −2 or −1; 1 mL per 45 kg of BW) and on d 90 ± 1 (1 mL per 68 kg of BW). On d 0, bulls were stratified by treatment, breed, and ranch of origin and assigned randomly to 8 pens in which they were fed a growing diet for 225 d. The diet was formulated to promote a 1.5-kg ADG at a DMI of 2.6% of BW and to meet or exceed NRC (2000) requirements for Ca, Co, Cu, I, Mg, Mn, Na, P, K, Se, and Zn. Initial BW were measured and </span>pretreatment blood plasma samples were collected on d −2 or −1. Breeding soundness examinations (BSE) were conducted and BW were measured at 10 and 12 mo of age (d 90 ± 1 and d 150 ± 1, respectively). Scrotal circumference was measured and semen samples were collected via </span>electro-ejaculation<span>. Motility and morphology of sperm were evaluated via light microscopy. Scrotal circumference, BW, and ADG did not differ (</span></span><em>P</em> ≥ 0.16) between treatments at any time. Proportions of control- and TM-treated bulls achieving minimal satisfactory BSE classifications did not differ at 10 mo of age (<em>P</em> = 0.98; 50 ± 3.8% for both TM and control) or at 12 mo of age (<em>P</em> = 0.43; 89 and 86 ± 2.2% for TM and control, respectively). Conversely, improved (<em>P</em><span> = 0.05) sperm motility was detected in TM-treated bulls compared with control-treated bulls at 12 mo of age; moreover, TM-treated bulls had greater (</span><em>P</em> ≤ 0.05) improvements in sperm morphology and motility between 10 and 12 mo of age than control-treated bulls. Among bulls that failed BSE at 10 mo of age, more TM-treated bulls tended (<em>P</em> = 0.10) to pass BSE at 12 mo of age than control-treated bulls (98 and 94 ± 1.6% for TM and control, respectively). Under the conditions of this experiment, sperm motility and morphology at 12 mo of age were improved in bulls treated with injectable TM at 7 and 10 mo of age compared with bulls treated with saline.</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"34 1","pages":"Pages 1-9"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01667","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79312187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superdosing phytase fed to mature boars improves semen concentration and reproductive efficiency","authors":"K.R. Stewart ,&nbsp;C.L. Bradley ,&nbsp;P. Wilcock ,&nbsp;F. Domingues ,&nbsp;M. Kleve-Feld ,&nbsp;J. Hundley ,&nbsp;F.A. Cabezón","doi":"10.15232/pas.2017-01646","DOIUrl":"10.15232/pas.2017-01646","url":null,"abstract":"<div><p><span>The purpose of this project was to evaluate the effects of superdosing phytase<span> fed to boars on sperm production, semen quality, and serum mineral concentrations. Thirty boars (9 to 12 mo of age, PIC 280) were enrolled in the study and were fed 2.5 kg/d of a commercial corn–soybean meal diet containing 500 phytase units/kg modified </span></span><em>Escherichia coli</em> phytase to release 0.15% available phosphorus and 0.16% Ca. The boars were blocked by age and randomly assigned to receive 1 of 2 top-dresses at 0.5 kg/d: (1) control (corn only) or (2) superdosed (corn plus 5,000 phytase units/kg <em>E. coli</em> phytase to equate to 3,000 phytase units/kg in the overall diet). Semen was collected weekly from all 30 boars for 12 wk and motility, mobility, and morphology evaluated at the time of collection. Monthly semen samples were shipped to Purdue University for additional assessment of motility, morphology, viability, and DNA denaturation. Serum mineral concentrations were determined on wk 1, 6, and 12. The concentration of sperm in the ejaculate was greater in the superdosed boars (<em>P</em> = 0.03), resulting in a tendency for an additional 3 doses (2.8 billion cells/dose) extended per ejaculate (<em>P</em> = 0.10) from a 13% increase in semen output. Some significant variations in motility, mobility, and morphology were found, but all semen samples fresh and stored were considered acceptable at industry standards for use in breeding doses. Serum minerals were reduced in boars fed superdosed levels of phytase, possibly due to a shift of minerals being used for reproduction.</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"34 1","pages":"Pages 95-102"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01646","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85704200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of magnetized water on productive traits of laying chickens","authors":"K. El-Sabrout,&nbsp;M. Hanafy","doi":"10.15232/pas.2017-01656","DOIUrl":"10.15232/pas.2017-01656","url":null,"abstract":"<div><p><span><span>This study examined the effect of using magnetized water on productive traits of Lohmann Brown hens during the egg production period (1 mo). A total of 400 hens were randomly distributed into 2 treatment groups with 10 replicates for each group. Hens were kept in 4 lines of 400 cages with the same environmental conditions. The first group (control) of hens in 2 lines of cages were provided tap water, and the second group (in 2 lines of cages) was provided magnetized water. The physical and chemical properties of water were determined using a pH meter, ion chromatography, and a </span>spectrophotometer. Data of egg yield, egg weight, eggshell thickness, eggshell weight, and mortality rate were recorded. Blood calcium and phosphorus concentrations (mg/dL) were also evaluated in hens at the end of the experiment. Compared with tap water (control), the magnetized water was more (</span><em>P</em> &lt; 0.05) alkaline and had greater (<em>P</em> &lt; 0.05) concentrations of salinity, total hardness, Na⁺, K⁻, Ca²⁺, Mg²⁺, Cl⁻, and HCO₃⁻. The results of egg yield and egg weight generally exhibited no significant (<em>P</em> &lt; 0.05) differences between the 2 groups. Also, there was no significant (<em>P</em> &lt; 0.05) effect of treatment on mortality rate. However, the magnetized water group had significantly (<em>P</em> &lt; 0.05) thicker and heavier eggshells compared with hens receiving tap water. The concentrations of calcium and phosphorus in blood were greater (<em>P</em> &lt; 0.05) for hens in the magnetized water group compared with hens in the control group. In the conditions of this experiment, magnetized water enhanced eggshell quality by increasing eggshell thickness and weight.</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"33 6","pages":"Pages 739-742"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01656","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79103308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of increased dietary sugar on dairy cow performance as influenced by diet nutrient components and level of milk production","authors":"M.B. de Ondarza ,&nbsp;S.M. Emanuele PAS ,&nbsp;C.J. Sniffen","doi":"10.15232/pas.2017-01648","DOIUrl":"10.15232/pas.2017-01648","url":null,"abstract":"<div><p>Interactions among diet nutrient parameters can influence dairy cattle response to added dietary sugar. With the objective to evaluate the effect of dietary sugar, 2 data sets with dietary information and production responses were compiled from published research that tested the effect of additional dietary sugar on dairy cattle performance. The first data set included 24 scientific papers (97 observations) with dietary forage NDF content ranging from 14.61 to 38.48% of diet DM. To evaluate the effect of dietary sugar in diets with a more narrow range in dietary forage NDF (17.37 to 29.51% of diet DM), the second data set omitted 3 of the scientific papers in the first data set, resulting in 85 observations. Mixed model linear regression analysis included treatment category [control, 1.5–3%, 3–5%, vs. 5–7% added dietary sugar (% of diet DM)], DIM category within treatment, control milk yield category within treatment, and several continuous nutrient variables. In cows producing &gt;33 kg of milk/d, added dietary sugar had a greater response (2.14 kg of 3.5% FCM/d; <em>P</em><span> &lt; 0.0001) than in cows producing &lt;33 kg of milk (0.77 kg of 3.5% FCM/d). Additional dietary sugar did not affect milk fat or protein percentage (</span><em>P</em> &gt; 0.15). Nutrient variables with a positive effect on 3.5% FCM yield included added starch and protein B₂ (insoluble in boiling neutral detergent but soluble in boiling acid detergent solution). Nonlinear statistical analysis predicted the optimal total dietary sugar to be 6.75% of diet DM. To optimize 3.5% FCM yield response when feeding additional dietary sugars, a low to moderate starch diet should be fed (22 to 27% of diet DM) in combination with a moderate to high soluble fiber content (6.0 to 8.5% of diet DM).</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"33 6","pages":"Pages 700-707"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01648","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82033276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Case Study: Recovery from ergot alkaloid-induced vasoconstriction for steers conditioned to grazing seedhead-suppressed and unsuppressed pastures of toxic endophyte-infected tall fescue1","authors":"J.A. Williamson ,&nbsp;G.E. Aiken PAS","doi":"10.15232/pas.2017-01655","DOIUrl":"https://doi.org/10.15232/pas.2017-01655","url":null,"abstract":"<div><p><span>Chemical seedhead suppression of toxic endophyte–infected (E+) tall fescue (</span><span><em>Lolium</em><em> arundinaceum</em></span><span><span><span>) can enhance steer performance and mitigate the adverse effects of ergot alkaloids on cattle physiology; however, it is not known if seedhead suppression can mitigate alkaloid-induced vasoconstriction and improve postgraze performance. A 2-yr experiment was conducted with </span>Angus<span> crossbred steers using a pasture phase to precondition steers to grazing seedhead-suppressed E+ tall fescue; unsuppressed E+ fescue; or a </span></span>bermudagrass (</span><em>Cynodon dactylon</em><span>), white clover (</span><em>Trifolium repens</em><span>), and Kentucky bluegrass (</span><em>Poa pratensis</em><span>) control. A pen phase followed to monitor luminal areas of the caudal artery for assessing alkaloid-induced vasoconstriction and BW to compare the E+ treatments with the nontoxic treatment. During the pen phase, luminal areas of caudal arteries in steers preconditioned on suppressed E+ were comparable (</span><em>P</em> &gt; 0.10) with those for nontoxic preconditioning on and after 28 and 13 d on the nontoxic diets (DNTD) in the first and second years, respectively. Caudal arteries in steers preconditioned on unsuppressed E+ were constricted compared (<em>P</em> &gt; 0.10) with the nontoxic preconditioned steers over all DNTD and from 0 to 34 DNTD in the first and second years, respectively. Body weights of steers preconditioned on suppressed pastures were similar (<em>P</em> &gt; 0.10) to the nontoxic steers, except for 0 and 8 DNTD in the first year and 6 DNTD in the second year. Body weights for steers on unsuppressed pastures were less (<em>P</em> &lt; 0.10) than those of nontoxic steers over all DNTD in each year. Results indicated that chemical seedhead suppression of E+ fescue can relieve alkaloid-induced vasoconstriction and improve postgraze performance.</p></div>","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"33 6","pages":"Pages 756-763"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15232/pas.2017-01655","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92053088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CASE STUDY: Recovery from ergot alkaloid-induced vasoconstriction for steers conditioned to grazing seedhead-suppressed and unsuppressed pastures of toxic endophyte-infected tall fescue","authors":"J. Williamson, G. Aiken","doi":"10.15232/PAS.2017-01655","DOIUrl":"https://doi.org/10.15232/PAS.2017-01655","url":null,"abstract":"ABSTRACT Chemical seedhead suppression of toxic endophyte–infected (E+) tall fescue (Lolium arundinaceum) can enhance steer performance and mitigate the adverse effects of ergot alkaloids on cattle physiology; however, it is not known if seedhead suppression can mitigate alkaloid-induced vasoconstriction and improve postgraze performance. A 2-yr experiment was conducted with Angus crossbred steers using a pasture phase to precondition steers to grazing seedhead-suppressed E+ tall fescue; unsuppressed E+ fescue; or a bermudagrass (Cynodon dactylon), white clover (Trifolium repens), and Kentucky bluegrass (Poa pratensis) control. A pen phase followed to monitor luminal areas of the caudal artery for assessing alkaloid-induced vasoconstriction and BW to compare the E+ treatments with the nontoxic treatment. During the pen phase, luminal areas of caudal arteries in steers preconditioned on suppressed E+ were comparable (P > 0.10) with those for nontoxic preconditioning on and after 28 and 13 d on the nontoxic diets (DNTD) in the first and second years, respectively. Caudal arteries in steers preconditioned on unsuppressed E+ were constricted compared (P > 0.10) with the nontoxic preconditioned steers over all DNTD and from 0 to 34 DNTD in the first and second years, respectively. Body weights of steers preconditioned on suppressed pastures were similar (P > 0.10) to the nontoxic steers, except for 0 and 8 DNTD in the first year and 6 DNTD in the second year. Body weights for steers on unsuppressed pastures were less (P","PeriodicalId":22841,"journal":{"name":"The Professional Animal Scientist","volume":"116 1","pages":"756-763"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76879930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}