Excessive dietary protein may affect MP use because of energetic costs of excreting excess N. Amino acids also may influence post-ruminal digestion. Therefore, two experiments were designed to evaluate the effects of MP intake and post-ruminal flow of AA on growth performance and pancreatic digestive enzymes. In experiment 1, treatments supplied different amounts of MP intake to cattle and the effects on growth performance and feeding behavior were evaluated. In experiment 2, duodenal infusion of glutamate or casein was examined and the effects on pancreatic enzymes were measured. Experiment 1 suggests that feeding steers 906 g MP/d in finishing diets supplied enough MP for the greatest growth performance and carcass characteristics. Interestingly, MP intake caused different responses on feeding behavior with greater effects on steers fed 626 and 1444 g MP/d. In experiment 2, casein infusion increased α-amylase activity but not trypsin activity. Glutamate did not influence pancreatic digestive enzymes.

Experiments were conducted to investigate effects of endophyte (Acremonium coenophialum Morgan-Jones and Gams) infection of tall fescue (Festuca arundinacea Schreb.) on grazing cattle and subsequent feedlot performance, serum minerals and prolactin, intake, digestibility, bite size, and biting rate. Grazing animal performance was measured April to October, 1989 and 1990, at two locations in VA. Effects of grazing low (<5%) and high (>70%) endophyte infected tall fescue, with and without white clover (Trifolium repens L.), were studied with yearling steers. At each location, two replicates were used with a stocking rate of .3 ha/steer (116 steers/yr). At the end of grazing, all animals were finished on a high corn silage diet and slaughtered. Daily gains of steers grazing low endophyte-infected pastures were higher (P<.01) than for those grazing high endophyte-infected pastures. Cattle grazing high endophyte-infected tall fescue with clover at Glade Spring gained at the same rate as those grazing the low endophyte-infected tall fescue without clover during Summer, 1989. During 1990, cattle at Glade Spring had higher (P<.05) daily gains than did those at Blackstone. Rectal temperatures were .5 to 1 °C higher (P<.05) for steers grazing infected pastures by June of each year at both locations. Prolactin concentrations were lower (P<.01) in cattle grazing endophyte-infected fescue within 28 d of initiation of grazing at both locations. Visual evaluation indicated that steers grazing high-endophyte pastures had rough hair coats compared to those grazing low endophyte pastures (P<.01), showing evidence of tall fescue toxicosis. Serum mineral analyses indicated no consistent influence of the endophyte. During feedlot finishing, there were no detrimental effects from previously grazing endophyte-infected tall fescue on animal performance. Forage DM yield, and CP in 1990, and IVDMD in 1989 and 1990 from Glade Spring were higher (P<.05) compared to Blackstone. Forage from Blackstone was typically higher in NDF, ADF, and lignin compared to Glade Spring. Forage from Glade Spring was higher in Ca, Mg, P, and Cu, compared to Blackstone. Diet selection, digestibility, biting size, and biting rate were measured with esophageally-fistulated steers grazing low (<5%) and high (>70%) endophyte-infected tall fescue, with and without white clover. Bite size was smaller (P<.05) in July compared to May, corresponding to decreased quantity of forage available. Bite size and biting rate were not affected by endophyte infection or inclusion of clover. In vitro DM digestibility was higher (P<.05) for high endophyte-infected tall fescue in July. Animals consumed a higher percentage of clover than was available in the sward. Intake and digestibility were estimated using 48 experimental animals and four esophageally-fistulated steers. Chromic oxide sustained-release boluses and forage IVDMD were used to estimate intake. The chromic oxide boluses were determined to be reliable for predicting intake of steers during a 21 d trial involving total fecal collection. Intake was higher (P<.01) in cattle grazing low endophyte-infected tall fescue compared to animals grazing high endophyte-infected fescue. Twenty-one Angus steers (256 kg) were used to compare the effect of 0 and 40% endophyte-infected tall fescue and orchardgrass hay on DM intake, daily gain, body temperature, serum minerals, and prolactin concentrations during an 8 wk study. Quality of the diets was low, as indicated by low CP (8.1 to 10.3%), and IVDMD (41.3 to 47.1%). Daily DM intake and daily gain were higher (P<.05) for animals consuming the noninfected tall fescue compared to animals fed the other hays. Body temperature and serum prolactin were not affected by diet. These data suggest that other factors, besides endophyte infection, are important in the etiology of tall fescue toxicosis. Some of the decreased performance of steers grazing endophyte-infected tall fescue was related to lower intake. Additional research is needed to evaluate higher levels of clover to possibly ameliorate some of the problems of tall fescue toxicosis. / Ph. D.

No description available.

Orientador: Alexandre Secorun Borges / Banca: Márcio Rubens Graaf Kuchembuck / Banca: Ivan Roque de Barros Filho / Resumo: O presente trabalho teve como objetivo determinar os elementos minerais no soro sangüíneo (magnésio, cobre, selênio, zinco, fósforo, cálcio, potássio, ferro) e no tecido hepático (cobalto, cobre, selênio, manganês, molibdênio e zinco) em seis diferentes momentos durante um período de dezesseis meses e verificar se houve variação entre eles. Foram utilizadas 25 novilhas mestiças Nelore, com idade média de 18 meses, que permaneceram durante todo o tempo do experimento no mesmo pasto de Brachiaria brizantha. Os animais ainda receberam mistura mineral comercial em cocho coberto e água à vontade e foram submetidos à coleta de fragmentos hepáticos e sangue para obtenção de soro. Análises da pastagem também foram realizadas nos mesmos momentos em que foram colhidas as amostras de soro e fígado (exceto em fevereiro 2003). A água e o sal mineral também foram analisadas. Os níveis médios dos elementos no tecido hepático foram, respectivamente para as seis diferentes colheitas: Co 0,27;0,27; 0,23;0,21; 0,23 e 0,24 ppm; Mn 9,07; 8,55; 8,67; 8,40; 7,90 e 7,25 ppm; Mo 4,18; 3,85; 3,68; 3,32; 3,54; 3,19 ppm; Zn 113,4; 101,94; 97,91; 92,46; 88,29 e 81,74 ppm; Cu 40,76; 36,33; 24,50; 24,70; 77,75 e 128,03 ppm e Se 0,86; 1,09; 0,72; 1,21; 0,91 e 0,75 ppm. Destes, os níveis de Co, Mn, Mo, Se e Zn foram considerados adequados para bovinos. Os níveis médios dos elementos no soro foram, para as quatro diferentes colheitas: Ca 118,72; 129,36; 125,19; 112,90; 96,76; 85,37 mg/L; P 109,28; 106,30; 117,03; 103,39; 115,78 e 107,75 mg/L; Mg 19,75; 23,62; 26,54; 20,96; 20,80 e 23,12 mg/L; K 139,64; 134,85; 114,19; 131,65; 130,57 e 116,60 mg/L; Cu 0,52; 0,73; 0,41; 0,59; 0,60 e 0,73 mg/L; Zn 1,19; 1,87; 1,38; 1,13;1,28 e 1,37 mg/L; Fe 2,52; 3,44; 2,21; 3,08; 3,00 e 2,89 mg/L e Se 1,19; 1,87; 0,19; 0,44, 0,40 e 0,51 mg/L...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of the present work was to determinate the mineral levels in beef cattle blood serum (magnesium, copper, selenium, zinc, phosphorus, calcium, potassium, iron) and liver (cobalt, copper, selenium, manganese, molibdenium and zinc) at six different moments throughout sixteen months, to verify the occurrence of variation among them. Twenty-five half-breed nelore heifers, all of them about 18 months old, stayed during the experiment in the same Brachiaria brizantha pasture. They also received commercial mineral mixture in appropriate feeders and free acess to water. Pasture were also analised at the same moments we did for serum and liver (except february 2003). Water and mineral mixture were analised as well. The average levels of the elements in the liver, respectively for the six different moments: Co 0.27,0.27, 0.23, 0.21, 0.23 and 0.24 ppm; Mn 9.07, 8.55, 8.67, 8.40, 7.90 and 7.25 ppm; Mo 4.18, 3.85, 3.68, 3.32, 3.54, 3.19 ppm; Zn 113.4, 101.94, 97.91, 92.46, 88.29 and 81.74 ppm; Cu 40.76, 36.33, 24.50, 24.70, 77.75 and 128.03 ppm and Se 0.86, 1.09, 0.72, 1.21, 0.91 and 0.75 ppm. The levels of Co, Mn, Mo, Se and Zn were considered appropriate for cattle. The average levels of the elements in the serum were, for the six different moments: Ca 118.72, 129.36, 125.19, 112.90, 96.76, 85.37 mg/L; P 109.28, 106.30, 117.03, 103.39, 115.78 and 107.75 mg/L; Mg 19.75, 23.62, 26.54, 20.96, 20.80 and 23.12 mg/L; K 139.64, 134.85, 114.19, 131.65, 130.57 and 116.60 mg/L; Cu 0.52, 0.73, 0.41, 0.59, 0.60 and 0,73 mg/L; Fe 2,52; 3,44; 2,21; 3,08; 3,00 and 2,89 mg/L; Se 1.19, 1.87, 0.19, 0.44, 0.40 and 0.51 mg/L and Zn 1.19, 1.87, 1.38, 1.13,1.28 and 1.37 mg/L. In the serum, Ca, P, Mg, Zn, Fe and Se levels were considered appropriate for beef cattle. There was correlation between the hepatic and serum levels of Cu...(Complete abstract, click electronic address below) / Mestre

In KwaZulu-Natal the production of beef in summer from veld is a common enterprise. Many techniques are available to optimise the productivity of this enterprise, from improving the quality of the grazing resource (planted pastures) to improving the diet of animals using nutritional supplements. To gain an insight into the production potential and financial returns possible from such improvements a trial was established at the Ukulinga Research Farm during two consecutive summer growing seasons (1997-1998 and 1998-1999). The aim was to determine the optimum beef production system for the area from both veld and kikuyu pastures. To evaluate the benefits of supplying supplementary nutrition, four alternate feed supplements, namely: 1) a Standard commercially available molasses-based protein/mineral/energy supplement; 2) a Brewers grain based protein/mineral/energy supplement, and two supplements consisting of the Brewers grain ration with either; 3) Avoparcin (an additive that improves dietary energy) or 4) Bentonite (an additive that increases the bypass of protein) were compared. As stocking rate has been shown to influence the quality of the diet consumed, the kikuyu pasture was grazed at both the recommended (1.92 LSD ha¯¹) and half the recommended stocking rate for the region. In addition, a commercial hormonal implant was applied to half of the cattle in each treatment. Grazing was monitored using the falling plate disc meter to measure pasture bulk density and laboratory analyses of herbage grab samples for digestibility and crude protein percentage. Cattle were weighed on a weekly basis and their condition was scored prior to slaughter. All enterprise costs and returns were recorded to facilitate financial analyses of the five treatments. Low rainfall and high midsummer temperatures had a detrimental effect on the productivity of the grazing and hence it was difficult to optimise production in either season. In the first season, a midsummer drought decreased the quality and quantity of both veld and kikuyu, limiting mass gain during the latter part of the season. A delay in the onset of rain at the start of the second season limited the available grazing season to 121 days as opposed to 154 days, though fodder production during the season was not limited. Trends in herbage production (quality and quantity) from veld showed moderate quality (Crude protein 7.02%; digestibility 50.2%) with an average available herbage of 1670 kg DM ha¯¹. As anticipated, kikuyu had higher quality (Crude protein 10.84%; digestibility 53.5%) and available herbage (2730 kg DM ha¯¹). These results were similar to regional benchmarks. The variable rainfall highlighted both the drought tolerance of veld and the minimum water requirements of kikuyu pastures. Lighter stocking rates tended to reduce the negative impact of moisture stress on Kikuyu pastures. The best method of producing beef (averaged over two seasons) was from heavily stocked Kikuyu pastures using the Standard supplement (1107.63 kg livemass ha¯¹). Cattle grazing veld and utilising the Avoparcin supplement produced beef at a rate of 95.96 kg ha¯¹. In comparison, the unsupplemented cattle grazing Kikuyu produced 834.87 kg ha¯¹, whilst veld grazing produced 64.43 kg ha¯¹. Hormonal implants significantly (P≤0.05) improved beef production from all sources of grazing. A lack of rain limited grazing time, causing all the cattle to be marketed whilst too lean - this negatively affected live mass gain and, hence, net financial. Although improved biological production is desirable, it is important to ensure that these gains are financially sustainable. Within the trial environment, implanted cattle fed the Standard supplement and grazing Kikuyu pastures at a high stocking rate provided the highest average gross margin of R 859.59 ha¯¹. Changing to this production system from unsupplemented veld improved expected profit by R 632.58 ha¯¹ (averaged over both seasons). Further financial analyses indicated that beef purchase price had the greatest influence on the added profit from switching from the control treatment. From a scientific standpoint these data are conclusive but it is important to remember that consumer pressure and concerns can often limit the introduction of production improvements. Such is the case with both hormonal implants and antibiotic feed additives (Avoparcin) although considering the impact of such limitations is speculative and beyond the scope of this trial. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Three experiments compared ruminal, physiological, and performance responses of beef steers consuming hay ad libitum and receiving grain-based supplements with (CAM) or without (CO) inclusion of camelina meal. In Exp. 1, 9 steers fitted with ruminal cannulas received CAM (2.04 kg of DM/d) or CO (2.20 kg of DM/d). Steers receiving CAM had reduced (P = 0.01) total DMI and tended to have reduced (P = 0.10) forage DMI compared to CO. No treatment effects were detected (P ≥ 0.35) for ruminal hay degradability parameters. In Exp. 2, 14 steers receiving CAM (1.52 kg of DM/d) or CO (1.65 kg of DM/d) were assigned to corticotropin-releasing hormone (CRH; 0.1 μg/kg of BW) and thyrotropin-releasing hormone (TRH; 0.33 μg/kg of BW) challenges. Steers receiving CAM had greater (P < 0.05) serum concentrations of PUFA compared to CO prior to challenges. Upon CRH infusion, mean plasma ceruloplasmin concentrations increased at a lesser rate in CAM compared with CO (P < 0.01). Upon TRH infusion, no treatment effects were detected (P ≥ 0.55) for serum TSH, T₃, and T₄. In Exp. 3, 60 steers were allocated to 20 drylot pens. Pens were randomly assigned to receive CAM (2.04 kg of DM/steer daily) or CO (2.20 kg of DM/steer daily) during preconditioning (PC; d -28 to 0). On the morning of d 0, steers were transported for 24 h. Upon arrival from transport on d 1, pens were randomly assigned to receive, in a 2 x 2 factorial arrangement, CAM or CO during feedlot receiving (FR; d 1 to 29). During PC, CAM had reduced (P < 0.01) forage and total DMI, and tended to have reduced (P = 0.10) ADG compared to CO. Plasma linolenic acid concentrations increased during PC for CAM, but not for CO (P = 0.02). Steers that received CAM during FR had greater (P < 0.05) mean plasma concentrations of PUFA, and reduced mean rectal temperature and concentrations of haptoglobin and ceruloplasmin during FR compared to CO. Therefore, camelina supplementation reduced forage and total DMI, did not alter thyroid gland function, increased PUFA concentrations in blood, and attenuated the acute-phase protein reaction elicited by neuroendocrine stress responses. In conclusion, camelina meal is a feasible ingredient to reduce stress-induced inflammatory reactions and potentially promote cattle welfare and productivity in beef operations. / Graduation date: 2012

Perennial ryegrass (PRG, Lolium perenne) is a hardy cool-season grass that is infected with the endophytic fungus Neotyphodium lolii, which enables the plant to be insect repellant and drought resistant, lowering the use of insecticides and fertilizers. However, this fungus produces the compound lolitrem B (LB, m/z 686.4) which causes the tremorgenic neurotoxicity syndrome 'ryegrass staggers' in livestock consuming forage which contains <2000 ppb LB. Ergovaline (EV, m/z 534) is a vasoconstrictor normally associated with tall fescue (Festuca arudinacea), but has also been found in endophyte-infected PRG. Past research has shown a strong linear correlation between levels of LB and EV in PRG. The purpose of this study was to examine the linear relationship between EV and LB in feces and determine common metabolites. To accomplish this, four groups of steers (n=6/group) consumed endophyte- infected PRG over 70 days consumed the following averages of LB and EV: group I 2254ppb LB/633 ppb EV; group II 1554ppb LB/ 373ppb EV, group III 1011ppb LB/259ppb EV, and group IV 246ppb LB/<100ppb EV. Group I in week 4 was inadvertently given a washout period at which time the steers consumed the amount of LB and EV given to group IV (control). Both feed and feces samples were extracted using difference solid phase extraction methods and quantified by HPLC-fluorescence for LB and EV. Concentrations of EV and LB obtained through HPLC-fluorescence in both PRG and feces showed a linear relationship. Additional screening for metabolites was conducted LC-MS/MS and showed possible oxidation and reduction metabolites for both toxins. / Graduation date: 2013

Made available in DSpace on 2014-06-11T19:23:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01-26Bitstream added on 2014-06-13T20:11:42Z : No. of bitstreams: 1 mouraesilva_fc_me_botfmvz.pdf: 536732 bytes, checksum: b483c8eb0344fa45e6c29e1db8477c14 (MD5) / Fundação para o Desenvolvimento da UNESP (FUNDUNESP) / O presente trabalho teve como objetivo determinar os elementos minerais no soro sangüíneo (magnésio, cobre, selênio, zinco, fósforo, cálcio, potássio, ferro) e no tecido hepático (cobalto, cobre, selênio, manganês, molibdênio e zinco) em seis diferentes momentos durante um período de dezesseis meses e verificar se houve variação entre eles. Foram utilizadas 25 novilhas mestiças Nelore, com idade média de 18 meses, que permaneceram durante todo o tempo do experimento no mesmo pasto de Brachiaria brizantha. Os animais ainda receberam mistura mineral comercial em cocho coberto e água à vontade e foram submetidos à coleta de fragmentos hepáticos e sangue para obtenção de soro. Análises da pastagem também foram realizadas nos mesmos momentos em que foram colhidas as amostras de soro e fígado (exceto em fevereiro 2003). A água e o sal mineral também foram analisadas. Os níveis médios dos elementos no tecido hepático foram, respectivamente para as seis diferentes colheitas: Co 0,27;0,27; 0,23;0,21; 0,23 e 0,24 ppm; Mn 9,07; 8,55; 8,67; 8,40; 7,90 e 7,25 ppm; Mo 4,18; 3,85; 3,68; 3,32; 3,54; 3,19 ppm; Zn 113,4; 101,94; 97,91; 92,46; 88,29 e 81,74 ppm; Cu 40,76; 36,33; 24,50; 24,70; 77,75 e 128,03 ppm e Se 0,86; 1,09; 0,72; 1,21; 0,91 e 0,75 ppm. Destes, os níveis de Co, Mn, Mo, Se e Zn foram considerados adequados para bovinos. Os níveis médios dos elementos no soro foram, para as quatro diferentes colheitas: Ca 118,72; 129,36; 125,19; 112,90; 96,76; 85,37 mg/L; P 109,28; 106,30; 117,03; 103,39; 115,78 e 107,75 mg/L; Mg 19,75; 23,62; 26,54; 20,96; 20,80 e 23,12 mg/L; K 139,64; 134,85; 114,19; 131,65; 130,57 e 116,60 mg/L; Cu 0,52; 0,73; 0,41; 0,59; 0,60 e 0,73 mg/L; Zn 1,19; 1,87; 1,38; 1,13;1,28 e 1,37 mg/L; Fe 2,52; 3,44; 2,21; 3,08; 3,00 e 2,89 mg/L e Se 1,19; 1,87; 0,19; 0,44, 0,40 e 0,51 mg/L... / The objective of the present work was to determinate the mineral levels in beef cattle blood serum (magnesium, copper, selenium, zinc, phosphorus, calcium, potassium, iron) and liver (cobalt, copper, selenium, manganese, molibdenium and zinc) at six different moments throughout sixteen months, to verify the occurrence of variation among them. Twenty-five half-breed nelore heifers, all of them about 18 months old, stayed during the experiment in the same Brachiaria brizantha pasture. They also received commercial mineral mixture in appropriate feeders and free acess to water. Pasture were also analised at the same moments we did for serum and liver (except february 2003). Water and mineral mixture were analised as well. The average levels of the elements in the liver, respectively for the six different moments: Co 0.27,0.27, 0.23, 0.21, 0.23 and 0.24 ppm; Mn 9.07, 8.55, 8.67, 8.40, 7.90 and 7.25 ppm; Mo 4.18, 3.85, 3.68, 3.32, 3.54, 3.19 ppm; Zn 113.4, 101.94, 97.91, 92.46, 88.29 and 81.74 ppm; Cu 40.76, 36.33, 24.50, 24.70, 77.75 and 128.03 ppm and Se 0.86, 1.09, 0.72, 1.21, 0.91 and 0.75 ppm. The levels of Co, Mn, Mo, Se and Zn were considered appropriate for cattle. The average levels of the elements in the serum were, for the six different moments: Ca 118.72, 129.36, 125.19, 112.90, 96.76, 85.37 mg/L; P 109.28, 106.30, 117.03, 103.39, 115.78 and 107.75 mg/L; Mg 19.75, 23.62, 26.54, 20.96, 20.80 and 23.12 mg/L; K 139.64, 134.85, 114.19, 131.65, 130.57 and 116.60 mg/L; Cu 0.52, 0.73, 0.41, 0.59, 0.60 and 0,73 mg/L; Fe 2,52; 3,44; 2,21; 3,08; 3,00 and 2,89 mg/L; Se 1.19, 1.87, 0.19, 0.44, 0.40 and 0.51 mg/L and Zn 1.19, 1.87, 1.38, 1.13,1.28 and 1.37 mg/L. In the serum, Ca, P, Mg, Zn, Fe and Se levels were considered appropriate for beef cattle. There was correlation between the hepatic and serum levels of Cu...(Complete abstract, click electronic address below)

Made available in DSpace on 2015-03-26T13:55:24Z (GMT). No. of bitstreams: 1 texto completo.pdf: 520868 bytes, checksum: 2d8a7216ec49d2191fe503c2a550a5bb (MD5) Previous issue date: 2014-02-21 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The present work was conducted aiming to evaluate the effects of feed restriction during post-weaning growing phase on animal performance, carcass traits and meat quality of Nellore feedlot finished with high-grain diet. To better discussing, the data were divided into two chapters; the first is about animal performance and carcass traits, while the second chapter is about meat quality. 39 young bulls with 8.5 ±0.2 months old and initial body weight of 230.4 ±5.6 kg, were used in this trial. At the beginning, five animals were slaughtered as reference group and the thirty-five remaining were allocated in one of the treatments, that were: low gain in growing phase and high gain in finishing (LH), medium gain in growing phase and high in finishing (MH) and high gain in both phases (HH). At the end of growing phase 5 LH, 6 MH and 6 HH animals were slaughtered and the remaining started the finishing phase and were slaughtered in the end of this phase. The intakes of dry mater (DM) and all nutrients did not differ (P>0.05) among the treatments when expressed as kg/d. However when DM and NDFap were expressed in g.kg BW-1.d- , were higher (P<0.05) for MH and LH than HH. The LH animals showed in the finishing phase greater (P<0.05) daily gain of body weight (BW) and empty body weight (EBW), greater carcass gain, greater carcass protein gain and greater carcass water gain than MH and HH. The LH and MH gain of non-carcass components was greater (P<0.05) than HH. The LH treatment had greater (P<0.05) feed efficiency and better carcass feed conversion than MH and HH. The BW and the EBW at the end of finishing phase were greatest for the HH animals, lowest for the LH and intermediate for MH that did not differ than HH and LH. The carcass weight and carcass dressing percentage were higher (P<0.05) for HH than others treatments. The HH treatment had greater (P<0.05) fat thickness. About the beef quality, at the end of growing phase significant difference (P>0.05) was observed for the final sarcomere length, with the highest average value to HH treatment, the lowest to LH and intermediate for MH that did not differ from the others two treatments. At the end of growing phase, the LH treatment showed a lower (P<0.05) redness (a*) than MH and HH treatments, that did not differ among themselves. At the end of growing phase, was found significant difference (P<0.05) for the beef yellowness (b*), the HH treatment had the highest average value, the LH treatment had the lowest and the MH had intermediate value, which did not differ from the others. At the end of finishing phase did not significant differences (P>0.05) were observed among the treatments for all evaluated beef traits. It is concluded that young Nellore cattle previously submitted to qualitative and quantitative food restriction, have higher daily gains of body components and are more efficient to convert food to carcass. Young Nellore cattle when previously submitted to qualitative restriction, exhibit complete catch up during finishing phase, without exhibit compensatory gain. Previously restricted animals have greater relative intakes of DM and fiber, higher gain of non-carcass components, lower transference from live weight gain to carcass gain, lower carcass dressing percentage and produce lighter and leaner carcasses. About the beef quality, it is concluded that dietary restriction post- weaning does not affect the beef quality after a long finishing phase. The evidences suggest that in the chilling conditions of this trial, the carcasses should be a minimum of 3.6 mm back fat thickness to prevent negative impacts of cold shortening on final sarcomere length and consequently on meat tenderness. / O presente trabalho foi desenvolvido com o objetivo de avaliar o efeito da restrição alimentar na fase de crescimento, após o desmame, sobre o desempenho produtivo e as características da carcaça e da carne produzida por tourinhos Nelore terminados em confinamento com dieta de alto grão. Os dados foram apresentados em dois capítulos, sendo no primeiro descrito o desempenho produtivo e as características de carcaça, enquanto o segundo capítulo abordou as características qualitativas da carne. Foram utilizados 39 machos não castrados Nelore, com idade média inicial de 8,5 ±0,2 meses e peso corporal médio de 230,4 ±5,6kg, que foram confinados. Inicialmente, foram abatidos cinco animais para determinar a composição corporal inicial, os demais foram distribuídos nos tratamentos, que consistiram de baixo ganho na fase de crescimento e alto na terminação (BA, n=10), médio ganho na fase de crescimento e alto na terminação (MA, n=12) e alto ganho em ambas as fases (AA, n=12). Ao final da fase de crescimento cinco animais do tratamento BA e seis dos MA e AA foram abatidos. Os demais permaneceram no experimento sendo abatidos ao final da fase de terminação. O consumo em kg/d de MS e dos nutrientes na terminação não diferiram (P>0,05) entre os tratamentos. O consumo de MS e FDNcp, quando expressos em g.kg BW-1.d-1, não diferiram (P>0,05) entre os tratamentos MA e BA, que foram maiores que o AA. O tratamento BA apresentou maiores (P<0,05) ganhos médios diários de peso vivo (PV), peso de corpo vazio (PCVZ), de carcaça e de proteína e água na carcaça em relação aos tratamentos MA e AA que não diferiram (P>0,05) entre si. O ganho de componentes não carcaça foi menor para o tratamento AA em relação aos demais e não diferiu (P>0,05) entre os tratamentos BA e MA. O tratamento BA apresentou maior eficiência alimentar e melhor conversão alimentar de carcaça que os demais tratamentos. O PV e o PCVZ ao final da fase de terminação foi maior (P<0,05) para o tratamento AA, menor para o BA e intermediário para o MA que não diferiu (P>0,05) dos demais tratamentos. Os valores de peso de carcaça e rendimento de carcaça foram maiores para o tratamento AA em relação aos demais. Os animais do tratamento AA apresentou maior (P<0,05) espessura de gordura subcutânea. Ao final da fase de crescimento, foi observada diferença significativa (P>0,05) para o comprimento final do sarcômero, sendo o valor médio maior para o tratamento AA, menor para o BA e intermediário para o MA que não diferiu dos outros dois tratamentos. Ao final da fase de crescimento foi observado também, um menor (P<0,05) valor de intensidade de vermelho (a*) para os animais do tratamento BA em relação aos tratamento MA e AA, que não diferiram entre si. No abate ao final da fase de crescimento, foi encontrado diferença significativa (P<0,05) para o valor de intensidade de amarelo (b*) da carne, sendo o maior valor médio obtido para o tratamento AA, o menor para o BA e valor intermediário foi obtido para o tratamento MA, que não diferiu dos demais. Não foram observadas diferenças significativas (P>0,05) para as demais características avaliadas nos bifes obtidos ao final da fase de crescimento. Não foi observada nenhuma diferença significativa (P>0,05) entre os valores médios dos tratamentos para as características qualitativas avaliadas nos bifes obtidos ao final da fase de terminação. Conclui-se então que, animais Nelore jovens submetidos à restrição alimentar quali e quantitativa prévia, apresentam maiores ganhos diários dos componentes corporais. Quando submetidos previamente à uma moderada restrição qualitativa, compensam na fase de terminação todo o peso que deixaram de ganhar durante a restrição, sem no entanto aumentarem expressivamente o seu ganho médio diário. Animais previamente restritos, apresentam maior consumo relativo de MS e de fibra, maior ganho de componentes não constituintes da carcaça, menor transferência do ganho de peso vivo para a carcaça, menor rendimento de carcaça e produzem carcaças mais leves e mais magras. Apesar dos animais em crescimento compensatório terem apresentado melhor conversão alimentar de carcaça na fase de terminação, considerando o período total do experimento, os animais em crescimento contínuo são mais eficientes na conversão de alimento em carcaça. Quanto às características qualitativas da carne, pode-se concluir que a restrição alimentar após o desmame não afeta as características qualitativas da carne quando os animais passam por longo período de terminação. Os resultados obtidos sugerem que, em condição de resfriamento da carcaça similar à do presente trabalho, as carcaças devem ter um mínimo de 3,6 mm de espessura de gordura subcutânea para prevenir impactos negativos do cold shortening sobre o comprimento final do sarcômero e consequentemente sobre a maciez da carne.

CAPES / O trabalho foi desenvolvido na Fazenda Modelo do Instituto Agronômico do Paraná (IAPAR) no município de Ponta Grossa, entre o período de Junho de 2011 a Março de 2012. Com o objetivo de avaliar os sistemas de desmame precoce e da amamentação controlada sobre o desempenho de vacas e bezerros durante o período reprodutivo, foram utilizadas 161 vacas mestiças Purunã e seus respectivos bezerros, distribuídos em três grupos: Desmame precoce (DP), foi realizado através do desmame dos bezerros com média de 75 dias de idade; o grupo Amamentação Controlada (AC), as vacas foram separadas de seus bezerros e colocadas a amamentar apenas uma vez ao dia durante o período da estação de monta; o terceiro grupo era do Desmame convencional (DC), em que as vacas mantiveram seus bezerros em aleitamento durante todo do tempo, sem alguma interferência no manejo durante todo o período de avaliação. As vacas de todos os grupos pariram em condição corporal acima de 3,3 pontos (escala de 1 a 5), não apresentando diferença na taxa de prenhez, sendo 90% para as vacas do DC; 96% para as vacas da AC e 97% para as vacas do DP. Quando em boas condições ao parto a utilização do desmame precoce e da amamentação controlada não trazem benefícios produtivos, podendo o desmame precoce provocar queda na eficiência reprodutiva do plantel de cria devido ao peso do bezerro ser 19,6% menor em relação ao desmame convencional. Os bezerros submetidos ao DP apresentaram menor (P<0,05) ganho de peso diário (0,56 kg) durante o período experimental em relação ao grupo AC e DC (0,95 kg e 0,88 kg, respectivamente) os quais não diferiram entre si (P<0,05). O manejo da amamentação controlada não provoca efeito no desempenho dos bezerros, podendo ser desmamados com peso similar aos bezerros mantidos ao pé da vaca. A categoria das vacas (Jovens, Adultas e Velhas) não apresentou interação com o sistema de desmame. Observou-se que Vacas jovens, são mais leves (P<0,05) ao parto e ao desmame de seus bezerros (383,89 e 399,40 kg, respectivamente) em relação às vacas adultas (444,07 e 451,92 kg) e velhas (452,35 e 470,49 kg). Desta forma as Novilhas acasaladas aos dois anos paridas em boas condições nutricionais apresentam a mesma eficiência reprodutiva que vacas adultas (47,64 e 48,35 kg de bezerro ao desmame/100 kg de vaca, respectivamente), ao passo que vacas velhas apresentam a menor eficiência reprodutiva no plantel de cria (42,99 kg de bezerro/100kg de vaca). O menor peso ao desmame de bezerros filhos de vacas primíparas e velhas é devido ao menor peso desde o nascimento até os 150 dias de idade, não havendo diferença no desempenho a partir deste período. / The study was developed at Fazenda Modelo an Experimental Estation belonged to the Insituto Agronômico do Paraná (IAPAR) in the city of Ponta Grossa, Pr, in the period from June 2011 to March 2012. Aiming to evaluate the systems of early weaning and controlled nursing about the performance of cows and calves during the breeding season, 161 crossbred Purunã cows and their calves were used and the were divided into three groups: Early weaning (DP), which was fulfilled weaning of calves with the average age of 75 days; the group of controlled nursing (AC), the cows were separated from their calves and placed to breastfeed only once a day during the breeding season; and the third group was the conventional weaning (DC), which the cows kept their calves together during the whole time without any interference in the management, with definitive weaning at seven months. Cows from all groups calved in body condition score above 3.7 points (scale from 1 to 5), with no significant difference in the pregnancy rate, 90% for cows in DC, 96% for cows for AC and 97% for cows of early Weaning. When in good condition at calving the use of early weaning or controlled nursing do not bring productive benefitis, early weaning can cause decline in reproductive efficiency of the breeding herd because of the weight of the calf to be 19.6% lower compared to conventional weaning. Calves subjected to the DP showed a lower overage (P <0.05) daily weight gain (0.56 kg) during the experimental period compared to the group at the AC and DC (0.95 kg and 0.88 kg, respectively) which did not differ from each other (P <0.05). The management of controlled nursing causes no effect on the performance of calves, that can be weaned with similar weight to calves maintained together the cow. As the cow category (Young, Adult and Old) showed no interaction with the system weaning, they were discussed independently. It was observed that young cows are lighter (P <0.05) at calving and weaning of their calves (383.89 and 399.40 kg, respectively) compared to mature cows (444.07 and 451.92 kg) and old (452.35 and 470.49 kg). Therefore, the Heifers bred at two years old, that calve in good nutritional conditions have the same reproductive efficiency that adult cows (47.64 and 48.35 kg of weaning calf to 100 kg/cow, respectively), while the old cows show lower reproductive efficiency in a breeding herd (42.99 kg of calf per 100kg/cow). The lower weaning weight of calves born from primiparous and old is because of the lower weight and performance since the birth to 150 days of age, with no difference in performance after this period.