Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] is an important forage crop in the United States and covers over 14 million ha. The presence of Neotyphodium coenophialum, an endophytic fungus in tall fescue, is associated with several disorders in grazing livestock, but also increased persistence of tall fescue. These disorders, commonly called fescue toxicosis, are responsible for large economic losses in the beef cattle industry each year. This research examined the effect of three fescue types [endophyte-infected Kentucky 31 tall fescue (E+), endophyte-free Kentucky 31 tall fescue (E-), non-ergot alkaloid-producing endophyte Q4508-AR542 tall fescue (Q)], and Lakota prairie grass (L; Bromus catharticus Vahl.) on animal response, alkaloid appearance, DMI, and copper status. Ergovaline (EV) is the most abundant ergot alkaloid in tall fescue and has previously been considered the causative toxin in fescue toxicosis. More recently it is simpler ergot alkaloids, such as lysergic acid amide (LSA) have been implicated. The objective of the first project was to evaluate animal performance and alkaloid (EV and LSA) appearance in forage and ruminal fluid of steers grazing E-, Q, E+, and L. Average daily gains were greater (P < 0.05) on E-, Q and L compared to E+, and there was a trend (P = 0.11) for gains on E- to be higher than with Q. The seasonal appearance of LSA in ruminal fluid was similar to the seasonal pattern of alkaloids in E+ forage. Ergovaline was not detectable in ruminal fluid of steers grazing E+. Alkaloids were not detectable in forage or ruminal fluid of steers grazing E-, Q, or L. The appearance of LSA in ruminal fluid of steers grazing E+ suggests that this alkaloid may contribute to fescue toxicosis. Low DMI of animals grazing E+ tall fescue is considered a key factor in decreased animal performance compared to other fescue types. The objective of the second project was to evaluate DMI of steers grazing E-, E+, Q, and L pastures using the alkane technique. Dry matter intake of steers grazing E- was greater (P < 0.001) than Q, E+, and L and DMI of steers grazing Q and E+ were similar (P > 0.10) in 2004. In 2005, DMI did not differ (P = 0.23) among fescue types. These results suggest that decreased DMI effects ADG of steers grazing E+ compared to those grazing E-, and lower DMI of Q suggests that the fescue variety Q4508 may not be the optimal variety for the incorporation on non-ergot alkaloid-producing endophytes. Reactive oxygen metabolites such as superoxide (O₂⁻) are produced by both endogenous and exogenous sources and an accumulation of these compounds can result in oxidative stress. Copper/zinc superoxide dismutase (SOD) is a Cu-based antioxidant metalloprotein that acts as a defense against oxidative stress by the scavenging of O₂⁻. <i>Neotyphodium</i>-infected tall fescue is typically lower in Cu which could potentially increase oxidative stress of animals grazing this forage. Therefore the objective of the third project was to investigate the Cu and SOD status of steers grazing E-, E+, Q, and L forages. Copper levels of all forages were below the dietary requirement (10μg Cu/g DM) of growing cattle. In 2004, steers grazing E+ exhibited lower (P <0.05) liver Cu compared to E- and Cu intake was lower (P < 0.001). Cu/Zn SOD enzymatic activity and mRNA relative expression did not differ (P > 0.10) among treatments. Copper intake of steers grazing E+ tall fescue was sufficient to maintain, but not replenish liver Cu, and SOD status did not appear compromised by grazing E+ at these Cu levels. / Ph. D.

Master of Science / Department of Animal Sciences and Industry / John A. Unruh / Forty-eight Brahman-cross male calves were fed to 26 mo of age and used to determine carcass cutability and meat quality characteristics of four muscles from intact bulls and steers castrated at 3, 7, or 12 mo of age grown under tropical pasture conditions. Longissimus lumborum (LL), Psoas major (PM), Gluteus medius (GM), and Semitendinosus (ST) steaks were aged for 2, 7, 14, or 28 d for Warner Bratzler shear force (WBSF) analysis. Live weight, carcass traits, and total subprimal yields were not affected by male sex condition. For PM, GM, and ST steaks, WBSF values were similar for steaks from intact bulls and steers castrated at all ages. For both PM and GM muscles, steaks aged for 28 d had the lowest (most tender) WBSF values and steaks aged for 2 d had the highest WBSF values. For the ST, WBSF values were highest for steaks aged 2 d. A treatment × aging interaction was detected for LL WBSF values. At 14 d of aging, LL steaks from steers castrated at 3 mo tended to have lower WBSF values than those from intact bulls. At 28 d of aging, steaks from steers had lower WBSF values than steaks from intact bulls and steaks from steers castrated at 3 mo tended to have lower WBSF values than steaks from steers castrated at 12 mo. For LL steaks from steers castrated at 3, 7 or12 mo, WBSF values linearly decreased with increased days of aging. Although all sensory panel data collected were not statistically different, LL steaks from steers castrated at 3 mo tended to have higher (more tender) scores for overall tenderness than steaks from intact bull. This study indicates that castration at 3 mo would be the recommended production practice as it provided the greatest improvement of LL tenderness over intact bulls with no differences in carcass traits or subprimal yields. The degree of improvement in tenderness due to aging is muscle dependent.

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Made available in DSpace on 2014-06-11T19:29:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-11-30Bitstream added on 2014-06-13T18:59:17Z : No. of bitstreams: 1 soutello_rvg_me_ilha.pdf: 132892 bytes, checksum: c6cef071d108accbe4359581e690ee32 (MD5) / Analisou-se os efeitos do tratamento anti-helmíntico estratégico e da suplementação protéica no ganho de peso de novilhos, do desmame até o abate. Foram utilizados 40 animais, com 8-9 meses de idade, 20 da raça Guzerá e 20 mestiços (Nelore - Angus), pesando em média 211,8 Kg. Esses animais foram distribuídos em quatro lotes, conforme o peso e permaneceram em quatro piquetes de aproximadamente 10 hectares cada, formado por Brachiaria decumbens. Dois lotes, grupos 1 e 2, receberam suplementação protéica comercial com 50 % de proteína bruta durante a seca e com 15 % durante as águas, fornecido ad libitum, e dois receberam somente mistura mineral, grupos 3 e 4 (controle). Dos lotes que receberam suplementação, apenas um foi tratado com endectocida Moxidectin 1% (grupo 1), o mesmo ocorrendo para os que receberam a mistura mineral (grupo 3). A cada 28 dias, os animais foram pesados e suas fezes colhidas para a contagem de ovos por grama de fezes (OPG) e coprocultura, e a cada 14 dias foi feito contagem de carrapatos de um lado do animal. O ganho de peso dos animais dos grupos um, dois, três e quatro foram de: 0,453 Kg, 0,320 Kg, 0,339 Kg e 0,231 Kg, por dia, respectivamente. Observou-se uma diferença significativa de peso entre os animais suplementados e tratados (grupo 1) em relação aos animais apenas tratados (grupo 3) e apenas suplementados (grupo 2), que por sua vez também foram significativamente diferentes dos animais que não receberam tratamento nem suplementação (grupo 4). A média de OPG nos grupos um, dois, três e quatro foi de: 19,82; 275,98; 31,34 e 254,55 respectivamente, com diferença significativa entre os animais tratados com anti-helmíntico (grupos 1 e 3) e os não tratados (grupos 2 e 4). As contagens médias de carrapatos nos grupos um, dois, três e quatro foram de: 1,2; 7,7; 0,8 e 9,3 respectivamente, com diferença... . / The effect of strategic anthelmintic treatment and protein suplementation was evaluated in steers using the weight gain as a parameter, during the period from weans to slawghtery. Forty animals were used, with 8-9 months of age, 20 of Guzera breed (Bos indicus) and 20 Nelore - Angus, weighing 211.8 kg in average. These animals were distributed in four groups and remained in four paddoks of 10 hectares each, formed by Brachiaria decumbens. Two groups had received commercial protein suplement with 50% of crude protein during the dry period and with 15% of crude protein, during the wet period, supplied ad libitum (groups 1 and 2) and the others two received only mineral mixture; groups 3 and 4 (control group). From those animals that received protein suplement, only one was treated with anthelmintic 1% Moxidectin (group 1), the same occurring for those animals that received mineral mixture (group 3). At 28 days of intervals the animals were weighed and theirs fecal samples were collected for nematode egg counts (EPG) and larval cultures, and at 14 days of intervals ticks were counted on a half of animal. The weight gain in group 1, 2, 3 and 4 was: 0.453 kg, 0.320 kg, 0.339 kg and 0,231 kg per day, respectively. Statistical significace of weight gain occurred between the animals supplemented and medicated (group 1) in relation to the animals that were only medicated (group 3) or betweem the groups that were only supplemented (group 2), and no medicated and suplemented (group 4). The average of EPG in groups 1, 2, 3 and 4 was of: 19.82; 275.98; 31.34 and 254.55 respectively, with significant difference in the animals medicated with anthelmintic (groups 1 and 3) and no medicated (groups 2 and 4). The tick counts in groups 1, 2, 3 and 4 was of: 1,2; 7,7; 0,8 e 9,3 respectively, with significant difference in the animals medicated (groups 1 and 3) and no... (Complete abstract, click electronic address below).

Orientador: Maria Conceição Zocoller Seno / Banca: Bruno Soerensen Cardoso / Banca: Wilma Aparecida Starke Buzetti / Resumo: Analisou-se os efeitos do tratamento anti-helmíntico estratégico e da suplementação protéica no ganho de peso de novilhos, do desmame até o abate. Foram utilizados 40 animais, com 8-9 meses de idade, 20 da raça Guzerá e 20 mestiços (Nelore - Angus), pesando em média 211,8 Kg. Esses animais foram distribuídos em quatro lotes, conforme o peso e permaneceram em quatro piquetes de aproximadamente 10 hectares cada, formado por Brachiaria decumbens. Dois lotes, grupos 1 e 2, receberam suplementação protéica comercial com 50 % de proteína bruta durante a seca e com 15 % durante as águas, fornecido "ad libitum", e dois receberam somente mistura mineral, grupos 3 e 4 (controle). Dos lotes que receberam suplementação, apenas um foi tratado com endectocida Moxidectin 1% (grupo 1), o mesmo ocorrendo para os que receberam a mistura mineral (grupo 3). A cada 28 dias, os animais foram pesados e suas fezes colhidas para a contagem de ovos por grama de fezes (OPG) e coprocultura, e a cada 14 dias foi feito contagem de carrapatos de um lado do animal. O ganho de peso dos animais dos grupos um, dois, três e quatro foram de: 0,453 Kg, 0,320 Kg, 0,339 Kg e 0,231 Kg, por dia, respectivamente. Observou-se uma diferença significativa de peso entre os animais suplementados e tratados (grupo 1) em relação aos animais apenas tratados (grupo 3) e apenas suplementados (grupo 2), que por sua vez também foram significativamente diferentes dos animais que não receberam tratamento nem suplementação (grupo 4). A média de OPG nos grupos um, dois, três e quatro foi de: 19,82; 275,98; 31,34 e 254,55 respectivamente, com diferença significativa entre os animais tratados com anti-helmíntico (grupos 1 e 3) e os não tratados (grupos 2 e 4). As contagens médias de carrapatos nos grupos um, dois, três e quatro foram de: 1,2; 7,7; 0,8 e 9,3 respectivamente, com diferença... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The effect of strategic anthelmintic treatment and protein suplementation was evaluated in steers using the weight gain as a parameter, during the period from weans to slawghtery. Forty animals were used, with 8-9 months of age, 20 of Guzera breed (Bos indicus) and 20 Nelore - Angus, weighing 211.8 kg in average. These animals were distributed in four groups and remained in four paddoks of 10 hectares each, formed by Brachiaria decumbens. Two groups had received commercial protein suplement with 50% of crude protein during the dry period and with 15% of crude protein, during the wet period, supplied "ad libitum" (groups 1 and 2) and the others two received only mineral mixture; groups 3 and 4 (control group). From those animals that received protein suplement, only one was treated with anthelmintic 1% Moxidectin (group 1), the same occurring for those animals that received mineral mixture (group 3). At 28 days of intervals the animals were weighed and theirs fecal samples were collected for nematode egg counts (EPG) and larval cultures, and at 14 days of intervals ticks were counted on a half of animal. The weight gain in group 1, 2, 3 and 4 was: 0.453 kg, 0.320 kg, 0.339 kg and 0,231 kg per day, respectively. Statistical significace of weight gain occurred between the animals supplemented and medicated (group 1) in relation to the animals that were only medicated (group 3) or betweem the groups that were only supplemented (group 2), and no medicated and suplemented (group 4). The average of EPG in groups 1, 2, 3 and 4 was of: 19.82; 275.98; 31.34 and 254.55 respectively, with significant difference in the animals medicated with anthelmintic (groups 1 and 3) and no medicated (groups 2 and 4). The tick counts in groups 1, 2, 3 and 4 was of: 1,2; 7,7; 0,8 e 9,3 respectively, with significant difference in the animals medicated (groups 1 and 3) and no... (Complete abstract, click electronic address below). / Mestre

Rumen acidosis is a common problem under feedlot conditions where cattle change from a roughage-based to a high concentrate-based diet. It is associated with an imbalance between lactic acid producing and lactic acid utilizing bacteria. Megasphaera eldenii is an important lactic acid utilizing bacteria which can now be produced for commercial use and supplemented for the prevention of lactic acid build up in the rumen and subsequent acidosis. The adaptation period is required in order for numbers of lactate utilizers such as M. elsdenii to increase to levels effective against subsequent build up of lactic acid. The purpose of this trial is to identify the effects of a strain, NCIMB 41125 (MeCH4), of Megasphaera elsdenii on the adaptation period of feedlot cattle on diets formulated for high starch levels. MeCH4 was isolated from the rumen of cattle adapted to high starch diets. By converting lactic acid in the rumen to volatile fatty acids (VFA’s) such as butyrate, M. elsdenii should be able to at least reduce the adaptation phase, if not totally eliminate the need for it without effects on intake patterns, feed conversion rates, health and carcass yield. . If results are positive, this strain of M. eldenii will have great economic implications to all feedlot farmers. There may be one major conclusion to be drawn from this trail and this was the fact that a decrease in adaptation days to reach the high concentrate grower diet had no statistically significant influence on key performance parameters relevant to the feedlot industry However, possibly the most attractive implication of these results is the lower need for roughage and therefore the implications tied in with the buying in and storage thereof. / Dissertation (MSc)--University of Pretoria, 2010. / Animal and Wildlife Sciences / unrestricted

The current National Academies of Sciences, Engineering and Medicine (NASEM) dry matter intake (DMI) prediction models are inadequate for DMI prediction of beef cattle in the Northern Great Plains. Four studies were conducted to account for additional variation in DMI and average daily gain (ADG) caused by weather variables. Experiment 1 and 2 had 13,895 steer-weeks observations, experiment 3 had 13,739 steer-weeks observations, and experiment 4 had 2,161 cow-weeks observations, respectively. Experiment 1 examined the influence of ambient temperature and solar radiation on DMI of beef steers. In experiment 2, 3, and 4, we examined the influence of ambient temperature, range of temperature, dew point, solar radiation, wind speed and their lags (two-week lag and monthly lag) on DMI of beef steers, ADG of beef steers, and DMI of beef cows, respectively. After adjusting for week of the year, linear and quadratic relationships of predictor variables on response variables were evaluated. In experiment 1 and 2, body weight (BW) had both linear and quadratic relationship with DMI of steers. In experiment 3 and 4, BW had a linear relationship with ADG of steers and DMI of cows, respectively. Week of the year, BW, and dietary energy density (NEm) were accounted for in the base model in experiment 1, 2 and 4 while in experiment 3, DMI was also accounted for. For the models, stepwise regression procedure was utilized. In experiment 1, ambient temperature and solar radiation interacted (P = 0.0001) and accounted for additional variation in DMI of beef steers. In experiment 2, weather variables and their interactions (P = 0.0001) accounted for additional variation in DMI of beef steers. In experiment 3, weather variables (P = 0.0001) accounted for additional variation in ADG of beef steers. In experiment 4, wind speed interacted (P <0.001) with ambient temperature and range of temperature which all accounted for additional variation in DMI of beef cows. These studies show that weather variables interact and cause variation in DMI and ADG in beef cattle. This has helped in better understanding the relationship between weather variables with DMI and ADG. This will improve the accuracy of DMI and ADG prediction equations and help beef cattle producers in managing their feed resources more efficiently.

A series of three experiments were conducted to evaluate different methods of estimating forage mass of tall fescue pastures, and dry matter intake and digestibility in beef steers under indoor and grazing conditions. Forage mass was estimated with the herbage cutting method (HCM) and three indirect methods; the pasture capacitance meter (PCM), the plate meter (PPM), and the visual estimation (VE). The coefficients of determination from the calibration equations were 0.686, 0.751, and 0.862 for the PCM, PPM, and VE, respectively. There were differences in forage mass estimates due to sampling method, sampling date, and their interaction. The second experiment was a digestion trial conducted with confined animals to determine the recovery rate of chromic oxide and alkanes from controlled release capsules and to evaluate the accuracy of the concurrent estimations of intake and digestibility. No difference was found in the recovery rate of either alkanes or chromic oxide during the 7 d of the collection period. Likewise, actual fecal output, dry matter intake, and digestibility were not different from the estimated values. However, estimated values had to be adjusted for the respective recovery rate. The third experiment was conducted under grazing conditions to evaluate the chromic oxide controlled release capsule technique in estimating intake and digestibilty. In this trial, although the recovery rate of the marker was extremely high (avg. = 1.89), the actual and estimated values of dry matter fecal output, intake, and digestibility were not different. Again the recovery rate had to be used as a correction factor. / Ph. D.

Previous research on grazing behavior has shown that ruminants will select a mixed diet. The use of adjacent monocultures is an essential tool for determining dietary preference of forages. Much of the work to date has been conducted with white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.). Partial preference for white clover over ryegrass has been reported consistently and partial preference for legumes is thought to occur regardless of the legume and grass species being evaluated. Two forage species, tall fescue (Festuca arundinacea Schreb. or Lolium arundinaceum (Schreb.) S.J. Darbyshire) and alfalfa (Medicago sativa subsp. sativa L.), which had not been evaluated together previously as adjacent monocultures were grazed by beef steers in the present set of experiments. Steers exhibited a partial preference for alfalfa of 61 to 65% when given a choice of grazing alfalfa or tall fescue as adjacent monocultures, regardless of the ground area proportion of the two forages offered. Steers grazing tall fescue monocultures spent more time ruminating (P = 0.02) and tended to graze less time (P = 0.06) than steers in adjacent monoculture treatments. Time spent idling, number of prehensions and mastications, and bite rate were similar (P > 0.05) among treatments. Steers grazing tall fescue monocultures spent less time standing, more time lying, were less active and took fewer steps (P ≤ 0.05) than steers in adjacent monoculture treatments. Grazing behavior was examined when alfalfa had not been in the previous diet of the steers. Cattle without previous experience grazing alfalfa spent 78% of the time grazing alfalfa, whereas after having experience grazing it they spent a lower (P = 0.04) proportion of their time grazing alfalfa (72%). Overall proportion of the day spent grazing both forages was lower (P = 0.0001) when alfalfa was novel (40%), compared to when steers were experienced grazing both forages (46%). Proportion of the day spent idling was greater (P < 0.0001) when alfalfa was novel (35%), compared to when both forages were familiar to the steers (26%). Previous research has reported that ruminants exhibit a diurnal pattern of preference by decreasing the proportion of white clover consumed from morning to late afternoon while increasing the proportion of perennial ryegrass in the diet. This is thought to be a strategy to increase fiber intake before nightfall or as a response to higher carbohydrate levels in grass in the afternoon. In the present study, proportion of grazing time in alfalfa was higher (P = 0.02) in the afternoon (76.8 %) than in the morning (72.1 %). While fiber concentration was higher in the tall fescue, carbohydrate concentrations were similar. Steers were not attempting to increase fiber intake in the afternoon in the present study. Dry matter intake of steers grazing adjacent monocultures of alfalfa and tall fescue was estimated with n-alkanes. Diet composition was estimated using n-alkanes and long chain alcohols (LCOH) in several different combinations. The use of LCOH added additional characterization of the forages, but diet composition estimates were not different (P ≥ 0.22) than when estimated using four different n-alkanes. Laboratory analysis costs may be reduced if n-alkanes alone can adequately characterize the forages being consumed, depending on the forage species in question. Meteorological conditions impacted DMI with intake being less in hotter conditions. Steers had similar partial preferences for alfalfa over tall fescue (P = 0.13, 79% and 70% alfalfa in yr 1 and 2, respectively) even though total DMI differed between years (P = 0.002, 9.4 kg d-1 and 4.5 kg d-1 in yr 1 and 2, respectively). Lower DMI in yr 2 was attributed to hotter air temperatures. When animals are consuming two different forages as adjacent monocultures such as in the current experiments, it is important to determine the proportion of each forage in the diet before calculating DMI using odd chain n-alkanes of the forage along with a dose even chained n-alkane. Dry matter intake can be overestimated if the proportion of the forages consumed is not estimated and accounted for in the equation. This would apply to other studies utilizing mixed swards or any diet containing multiple components that differ in concentration of the n-alkane being used for DMI estimation. Analysis of n-alkane concentration should be performed on each item in the diet and the proportion of each item in the diet estimated so that the right value can be used in the calculation. Differences in marker concentrations between years also indicate the importance of analyzing those concentrations in the feed or forage at the time of fecal collection and not using values reported from previous research. / Ph. D.

Endophyte infected Tall fescue (Festuca arundinacea Schreb.) is the most dominant grass used for pasture in the Southeastern U.S. As a result, fescue toxicosis is a major concern. Producers need alternative forages for grazing cattle that do not have this negative aspect. The objective of this experiment was to determine the grazing behavior of cattle grazing Lakota (L) prairie grass (Bromus catharticus Vahl.), endophyte infected (E+), endophyte free (E-), and novel endophyte (Q) tall fescues. Angus-crossbred steers (279±8 kg) steers wore electronic behavior data recorders in four sampling periods, and direct visual appraisals of behavior were taken in five sampling periods during the months of May to September, 2004. Overall, during the visual appraisal phase steers grazing L spent most time (P<0.05) grazing while E+ spent the least time grazing. Overall, steers grazing E+ spent more time (P<0.05) idling than those on L, E-, or Q. Steers grazing E+ spent more time (P<0.05) standing than steers grazing Q. Steers grazing Q and E- spent more time (P<0.05) lying than those grazing E+. During the data recorder phase there were no significant differences between treatments for time spent grazing. Steers grazing E+ spent less time (P<0.05) lying and ruminating than steers grazing Q or L. Conversely, time spent standing and idling for steers grazing E+ was higher (P<0.05) than for steers grazing Q or L. These results indicate that L, E-, and Q may offer benefits to producers due to more time spent in productive activities during summer months. / Master of Science