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Serum prolactin (PRL) and testosterone concentrations, body weight, body composition, semen quality, and semen freezing potential for bulls grazing the toxic tall fescue (Lolium arundinaceum [Schreb.] Darbysh. = Schedonorous arundinaceum [Schreb.] Dumort.) cultivar Kentucky 31 (E+) compared with a novel endophyte cultivar lacking ergot alkaloids (E-) were evaluated. Angus bulls were allotted to treatment (Day 0) and grazed E+ or E- for 155 days. Treatment-by-day interaction was significant (P < 0.05) for serum PRL concentrations with E+treated bulls exhibiting reduced PRL values compared with E- control bulls, but no differences were observed for serum testosterone concentrations (P > 0.05). Further, bulls on the E+ treatment exhibited decreased total gain, average daily gain, and body weight by Day 140 (P < 0.05) compared with the E- bulls. Rump muscle depth was lower because the treatment in bulls grazing E+ compared with E- (P < 0.05) and intramuscular fat in the E- bulls compared with the E+ group was higher by Day 155 (P < 0.05). Analysis of ejaculates showed significant treatment × day effects for sperm concentration with lower values observed for bulls on the E+ treatment (P < 0.05). The percent normal morphology was reduced in ejaculates from E+ bulls compared with E- bulls (P < 0.05), and the difference was due to an increase in abnormal sperm present in the E+ ejaculates from Day 84 to 140 (P < 0.05). In addition, spermatozoa motility and progressive motility were decreased on thawing in semen samples from E+ bulls compared with E- bulls (P < 0.05)., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Angus-cross steers (n = 60) were used to assess the effect of forage species [alfalfa (AL; Medicago sativa L.), bermudagrass (BG; Cynodon dactylon), chicory (CH; Cichorium intybus L.), cowpea (CO; Vigna unguiculata L.), and pearl millet (PM; Pennisetum glaucum (L. R Br.)] in replicated 2-ha paddocks for finishing on cattle performance, carcass quality, and meat quality in a 2-yr study. Steers were blocked by BW and assigned randomly to finishing-forage treatments before the start of the experiment. Steers grazing AL and CH had greater (P < 0.05) ADG than those grazing for BG, CO, and PM, whereas AL produced more (P < 0.05) gain/ha than CH, CO, and PM. Days steers spent grazing were longest (P < 0.05) for PM and shortest (P < 0.05) for CO. Steers grazing BG and CO produced heavier (P < 0.05) HCW than steers grazing BG and PM. Dressing percentage was greatest (P < 0.05) in steers grazing CO, and grazing AL resulted in greater (P < 0.05) dressing percentages than grazing BG, CH, and PM. Grazing AL and CH produced carcasses with more (P < 0.05) fat at the 12th rib than steers grazing warm-season grasses (BG and PM). Marbling scores tended to be greater (P = 0.06) for CO, but carcasses from steers grazing CO received greater (P < 0.05) quality grades than AL and CH. Trans-11 vaccenic (C18:1 trans-11; TVA) acid concentration in the LM was greater (P < 0.05) for BG than CH, CO, and AL. Conjugated linoleic acid, cis-9 trans-11 isomer, concentration was greatest (P < 0.05) for BG and PM than AL, CH, and CO. Grazing CH and PM increased (P < 0.05) the ratio of omega-6 to omega-3 fatty acids in the LM compared with AL, BG, and CO. Grazing legumes (AL and CO) resulted in lower (P < 0.05) Warner-Bratzler shear force values than other forage species. Consumers rated steaks from steers finished on AL and CO pastures greatest (P < 0.05) and steaks from steers finished on BG and CH least (P < 0.05) for overall palatability. Consumer preference was greatest (P < 0.05) for steaks from steers finished on AL and least (P < 0.05) for steaks from steers finished on BG and CH. Finishing steers on AL and CH during summer increased steer performance (> 1 kg/d). Finishing on legumes (AL and CO) increased dressing percentage, reduced Warner-Bratzler shear force values, and increased consumers preference, whereas finishing on grasses (BG and PM) enhanced anticarcinogenic fatty acid concentrations.

Cattle use of riparian areas may lead to stream water contamination with nutrients, pathogens, and sediments. Providing alternative water away from the stream may reduce the amount of time cattle spend near streams and therefore reduce contamination. We conducted this study to 1) evaluate the effect of providing water troughs outside of the riparian zones on the amount of time cattle spend in riparian zones, and 2) evaluate if environmental factors such as temperature and humidity affect the impact of water trough availability on the amount of time cattle spend within riparian and nonriparian locations. Global positioning system (GPS) collars were used to document cow locations every 5 min in 2 mixed tall fescue/common bermuda-grass pastures of the Georgia Piedmont in the United States. We found that when the temperature and humidity index (THI) ranged between 62 and 72, providing cattle with water troughs outside of riparian zones tended to decrease time cattle spent in riparian zones by 63% (52 min x d(-1); P = 0.11). When THI ranged between 72 and 84, nonriparian water availability did not have a significant impact on the amount of time cattle spent in the riparian zone or in riparian shade. These results suggest that water troughs placed away from unfenced streams may improve water quality by reducing the amount of time cattle spend in riparian zones when environmental conditions as evaluated by THI are not stressful.

Cow and calf performance was determined in a 2-yr, 2 x 2 factorial, grazing experiment using Coastal or Tifton 85 (T85) replicated Bermudagrass pastures (4 pastures each; each pasture 4.86 ha), without or with aeschynomene creep-grazing paddocks (n = 4, 0.202 ha each, planted in May of each year, 13.44 kg/ha). On June 10, 2004, and June 8, 2005, 96 winter-calving beef "tester" cows and their calves were grouped by cow breed (9 Angus and 3 Polled Hereford/group), initial cow BW (592.9 +/- 70.1 kg, 2-yr mean), age of dam, calf breed (Angus, Polled Hereford, or Angus x Polled Hereford), calf sex, initial calf age (117 +/- 20.1 d, 2-yr mean), and initial calf BW (161.3 +/- 30.4 kg) and were randomly assigned to pastures. Additional cow-calf pairs and open cows were added as the forage increased during the season. Forage mass was similar for all treatment pastures (P > 0.70; 2-yr mean, 6,939 vs. 6,628 kg/ha, Coastal vs. T85; 6,664 vs. 6,896 kg/ha, no creep grazing vs. creep grazing). Main effect interactions did not occur for performance variables (P > 0.10; 2-yr means), and year affected only the initial and final BW of the calves and cows. The 91-d tester calf ADG was greater for calves grazing T85 than Coastal (0.94 vs. 0.79 kg; P < 0.01), and for calves creep grazing aeschynomene compared with calves without creep grazing (0.90 vs. 0.82 kg; P < 0.03). Calf 205-d adjusted weaning weights were increased for calves grazing T85 compared with Coastal (252.9 vs. 240.3 kg; P < 0.01) and for calves with access to creep grazing (249.9 vs. 243.3 kg; P < 0.05). The IVDMD of esophageal masticate from pastures had a forage x creep grazing interaction (P < 0.05; Coastal, no creep grazing = 57.4%; Coastal, creep grazing = 52.1%; T85, no creep grazing = 59.1%; T85, creep grazing = 60.0%), and IVDMD was greater (P < 0.05) for T85 than for Coastal pastures. Cows were milked in August 2004, and in June and August 2005, with variable milk yields on treatments, but increased milk protein (P < 0.05) for cows grazing T85 compared with Coastal pastures in August each year, contributing to increased calf gains on T85 pastures. These results complement previous research with T85 and indicate increased forage quality and performance of cattle grazing T85 pastures. Calf gains on T85 pastures and for calves on creep-grazed aeschynomene paddocks were high enough to influence the efficiency of cow-calf operations.

Eighteen Angus steers (438 +/- 4 kg of BW) were supplemented with varying levels of corn oil (0 g/kg of BW, none; 0.75 g/kg of BW, MED; or 1.5 g/kg of BW, HI) on rotationally stocked, endophyte-free tall fescue to determine the effect of supplemental oil level on in vivo digestibility, intake, performance, and carcass traits. Pelleted cottonseed hulls were used as a carrier for the oil supplements, and all supplements were offered to steers using Calan gate feeders for individual intake determination. On d 49, each steer was dosed with a controlled-release capsule containing chromium sesquioxide, and fecal samples were obtained 12 d later over a 7-d period to estimate fecal output that, with forage, supplement, and fecal indigestible NDF concentration, was used to estimate DMI and in vivo total diet digestibility. Steers were slaughtered at the end of the 116-d grazing period, and carcass data were collected at 24 h postmortem. Total fatty acid intake linearly increased with corn oil supplementation, and forage DMI, total DMI, and total DE intake were linearly decreased (P < 0.01). The decrease in total DMI was reflected in forage substitution rates greater (P < or = 0.01) than 1, with a trend (P = 0.09) for a greater substitution rate in HI than in MED. In vivo DM, OM, and NDF digestibility were linearly decreased (P < 0.01) by corn oil supplementation. Average daily gain and final BW tended (P = 0.09) to increase linearly in response to oil level. Oil conversion (0.36 kg of BW gain/kg of corn oil) was greater (P < or = 0.05) than zero and did not differ (P = 0.15) between MED and HI. Dressing percent (P = 0.09), carcass weight (P = 0.01), and carcass backfat thickness (P = 0.01) increased linearly with oil supplementation. No treatment effect was observed for carcass LM area, KPH percentage, marbling score, or yield grade (P > 0.10). Oil supplementation to grazing steers linearly reduced forage DMI intake; however, animal performance was maintained and tended to be greater for oil-supplemented cattle. Oil supplementation increased carcass fat thickness and weight without altering other carcass quality parameters.

Three Angus steers (410 kg) cannulated in the proximal duodenum were used in a replicated 3 x 3 Latin square to evaluate the effects of dietary lipid level and oil source on ruminal biohydrogenation and conjugated linoleic acid (CLA) outflow. Dietary treatments included: 1) typical corn (TC; 79.2% typical corn), 2) high-oil corn (HOC; 79.2% high-oil corn), and 3) the TC diet with corn oil added to supply an amount of lipid equal to the HOC diet (OIL; 76.9% TC + 2.4% corn oil). Duodenal samples were collected for 4 d following 10-d diet adaptation periods. Data were analyzed with animal, square, period, and treatment in the model and planned, nonorthogonal contrasts were used to test the effects of dietary lipid content (TC vs HOC and OIL) and oil source (HOC vs OIL) on ruminal biohydrogenation. Intake and duodenal flow of total long-chain fatty acids were increased (P < 0.05) by over 63% for diets containing more lipid regardless of oil source. Apparent ruminal dry matter and long chain fatty acid digestibilities were not altered (P > 0.05) by dietary lipid level or oil source. Ruminal biohydrogenation of total and individual 18-carbon unsaturated fatty acids was greater (P < 0.05) for diets with higher lipid content. Biohydrogenation of oleic acid was greater (P < 0.05) for HOC than OIL, but biohydrogenation of linoleic acid was lower (P < 0.05) for HOC than OIL. Duodenal flows of palmitic, stearic, oleic, linoleic, and arachidic acids were more than 30% greater (P < 0.05) for diets containing more lipid. Flow of all trans-octadecenoic acids was greater (P < 0.05) for diets containing more lipid. Corn oil addition increased (P < 0.05) the flow of trans-10 octadecenoic acid and the trans-10, cis-12 isomer of CLA by threefold compared to feeding high-oil corn. Feeding high-oil corn or adding corn oil to typical corn rations increased intake, biohydrogenation, and duodenal flow of unsaturated long-chain fatty acids. Compared with high-oil corn diets, addition of corn oil increased duodenal flow of trans-10, trans-12 and cis-12 isomers of octadecenoic acid and the trans-10, cis-12 isomer of CLA. The amount of cis-9, trans-11 isomer of conjugated linoleic acid flowing to the duodenum was less than 260 mg/d, a value over 20 times lower than flow of trans-11 vaccenic acid indicating the importance of tissue desaturation for enhanced conjugated linoleic acid content of beef.

A study involving a 2 x 2 x 2 factorial arrangement of treatments was conducted to evaluate effects of hybrid (Pioneer 3335 and 3489), maturity (half milkline and blacklayer), and mechanical processing (field chopper with and without on-board rollers engaged) on intake and digestibility of corn silage. Forty Angus steers (322 +/- 5.2 kg BW) were assigned to the eight silage treatments (five steers per treatment) and individually fed using electronic gates. Diets consisted of 60% corn silage and 40% chopped alfalfa hay (DM basis). Following a 5-d adaptation period, intake was measured for 7 d and subsequently fecal samples were collected for 5 d. Chromic oxide (5 g/d) was fed beginning 7 d before fecal sample collection and digestibility was determined by the ratio of Cr in the feed and feces. Steers were reallocated to treatments and these procedures were repeated, providing 10 observations per treatment. In addition, all silages were ruminally incubated in six mature cows for 0, 8, 16, 24, 48, and 96 h to determine extent and rate of DM, starch, NDF, and ADF disappearance. Processing increased DMI of hybrid 3489 but did not affect DMI of hybrid 3335 (hybrid x processing; P < 0.06). Total tract digestibility of DM, starch, NDF, and ADF decreased (P < 0.01) as plant maturity increased. Maturity tended to decrease starch digestibility more for hybrid 3489 than for hybrid 3335 (hybrid x maturity; P < 0.10). Processing increased (P < 0.01) starch digestibility but decreased (P < 0.01) NDF and ADF digestibility, resulting in no processing effect on DM digestibility. There was a numerical trend for processing to increase starch digestibility more for latethan for early-maturity corn silage (maturity x processing; P = 0.11). Processing increased in situ rates of DM and starch disappearance and maturity decreased in situ disappearance rates of starch and fiber. These data indicate that hybrid, maturity, and processing all affect corn silage digestibility. Mechanical processing of corn silage increased starch digestibility, which may have been associated with the observed decreased fiber digestibility.

Sixty crossbred beef steers (initial BW = 412 kg) were used in a 83-d finishing study to determine the effect of feeding dry rolled high-oil corn on performance and total-tract digestibility of finishing diets. Steers were allotted by weight to the following dietary treatments: 1) control corn (C; 82% normal corn, 12% triticale silage), 2) high-oil corn (HO; 82% high-oil corn, 12% silage), and 3) high-oil corn formulated to be isocaloric to C (ISO; 74% high-oil corn, 20% silage). Total lipid content was 4.9% (DM basis) for normal corn and 7.0% for high-oil corn. Steers were individually fed using electronic gates. Quantity of feed offered and refused was recorded daily. Fecal samples were collected on d 63 to 66 of the trial to determine digestibility. Chromic oxide was fed as an indigestible marker for 7 d before fecal collection began. Planned contrasts of HO vs C and ISO vs C were used to assess treatment differences. Dry matter intake was greater for steers fed C vs HO (P < 0.01) or C vs ISO (P < 0.01), but daily gain and feed efficiency were not affected (P > 0.05) by treatments. Digestibility of DM, OM, starch, and GE was greater (P < 0.05) for the HO diet than the C diet, but lipid digestibility did not differ among treatments (P > 0.05). The combined effect of greater GE content and digestibility resulted in greater (P < 0.01) DE content for the HO than for the C diet. Calculated DE of the corn was 8.3% greater (3.74 Mcal/kg; P < 0.01) for the HO diet and 6.5% greater (3.67 Mcal/kg; P < 0.01) for the ISO diet than the corn in the C diet (3.25 Mcal/kg). Dry matter and GE digestibility did not differ (P > 0.05) between the C and ISO diets. Steers consuming ISO had greater (P < 0.05) starch digestibility than steers fed the C diet. Although HO had higher DE, DE intake was similar (P > 0.05) for HO and C due to lower DMI for HO. These results indicate that available energy is greater from high-oil corn than from typical corn, but depressed voluntary feed intake prevented performance improvements and resulted in equal energy intakes between high-oil corn and typical corn diets.

The predominant cool-season forage in the southeastern United States is the tall fescue cultivar Kentucky 31 (KY31). Kentucky 31 possesses an endophyte (Epichloë coenophiala), which produces a family of toxins called ergot alkaloids. These toxins negatively affect the physiology of animals on consumption and result in the syndrome known as fescue toxicosis. Currently, the United States annually produces approximately 11.4 billion kg of beef, of which 25% originates in the southeastern region of the United States where forage systems frequently are tall fescue based. Cattle within this forage system exhibit reduced gains and reproductive performance. The result is a reduction in the nation's beef supply with annual revenue losses recently estimated at approximately US$1 billion. Our hypothesis is that exposure to these ergot alkaloids in conjunction with limited availability of nutrients decreases bull semen quality and fertility. Although the literature is clear that these toxins affect BW, body temperature, blood flow, hair growth, and female reproduction in cattle, their effect on bull reproduction and the mechanisms through which the toxins act are not well defined. Six studies published from 2004 to 2015 assessed bull growth, body composition, and semen quality of young beef bulls exposed to ergot alkaloids. If semen quality or fertility is altered, the mechanisms involved may be either direct effects of ergot alkaloids through neurotransmitter receptors or indirect effects such as inhibiting the release of prolactin (PRL). The possible effects of ergot alkaloids or PRL require establishing the presence or absence of dopamine, adrenergic, serotonin, or PRL receptors in the testis, epididymis, and sperm cell of the bull. The objective of this review is to relate our findings to the few previous studies conducted that evaluated the impact of fescue toxicosis on bull reproduction and to propose possible mechanisms of action for lowered semen quality. [ABSTRACT FROM AUTHOR]

Eight paddocks (0.8 ha/paddock) were utilized near Eatonton, GA to determine the effects of tall fescue endophyte strain and white clover presence on urinary ergot alkaloid excretion and animal performance. Jesup tall fescue infected with a toxic endophyte or a nonergot alkaloid-producing endophyte (AR542; aka "MaxQ") was planted in four paddocks respectively. Two paddocks of each endophyte type were also over-seeded with Durana white clover. Each paddock was grazed with a minimum of two tester steers (mean initial wt 311 kg) in spring of 2003 - 2005. Animal gain, botanical composition, forage availability, and urine alkaloid concentration was monitored at 28 d intervals. Paddocks were grazed for 125, 56, and 113 d in 2003, 2004, and 2005. Put-and-take grazing was utilized to maintain similar forage availability. Data were analyzed as a completely randomized design with a 2X2 factorial arrangement of treatments. Paddock was the experimental unit. Endophyte type and clover were main effects. Drought in 2004 shortened the grazing season and decreased (P<0.01) gain/ha by approximately 50% for all treatments. Daily gain of cattle grazing toxic endophyte was similar (P=0.30) to AR542 in 2003, but was lower (P<0.05) in 2004 and 2005. Cattle grazing toxic endophyte had decreased gain/ha (P<0.01) and increased urine alkaloid concentration (P<0.01) regardless of year. White clover decreased carrying capacity (P<0.01) but improved ADG (P<0.01) and gain/ha (P<0.01). No endophyte x clover interaction was detected for ADG (P = 0.38). Cattle grazing white clover and toxic tall fescue had intermediate (P<0.05) urine alkaloid concentrations compared to toxic fescue without clover or all nontoxic tall fescue treatments. The lack of a significant clover x endophyte type interaction for average daily gain suggests that the alkaloid dilution observed in this study was inadequate to completely offset tall fescue toxicosis and improved animal performance from clover was associated with increased nutrient density. [ABSTRACT FROM AUTHOR]