ABSTRACT. This study evaluated the influence of the quantitative traits measured by real-time ultrasound (adjusted longissimus muscle area [AdjLMA], adjusted rump fat thickness [AdjRFT], and adjusted marbling [AdjMAR]) as well as age at first breeding [AFB] and adjusted weight [AdjWeight], on the probability of occurrence of early pregnancy (EP) in 55 Nellore heifers, and also performed an economic analysis. All calves received supplementation in creep-feeding (ad libitum), and at weaning (average age= 210 ± 30 days; average weight= 241 ± 33 kg) until first breeding by artificial insemination (May to November) all heifers were managed in the same group (two paddocks of 25 ha each evenly covered with Urochloa Marandu Grass) and received protein-energy supplementation (1% of average BW per animal/day). The quantitative variables were collected immediately after timed artificial insemination (average age= 392 ± 27 days; average weight= 431.90 kg), and the pregnancy diagnosis was completed at 30 days following insemination. For economic analysis, two systems were compared (age at first breeding at 13 and 24 months). The greater adjusted weight on the first breeding increased the probability of occurrence of early pregnancy, while the greater adjusted longissimus muscle area reduced. In addition, intensive meat production systems provide greater economic return throughout cow-calf operation.

Resumo Objetivou-se avaliar a qualidade espermática do sêmen de touros suplementados com selênio (Se) na dieta. Foram utilizados 16 touros Brangus, igualmente distribuídos em grupo controle (GC) e grupo Se (GSe − 0,1mg de Se/kg de MS de dieta). O experimento teve duração de 75 dias, e os animais foram suplementados por 60 dias. Foram realizadas quatro coletas de sêmen durante o período (0, 30, 60 e 75 dias) por animal. As amostras foram avaliadas quanto a motilidade e vigor espermáticos, integridade e funcionalidade da membrana plasmática (teste de expansão hiposmótico - HIPO) e viabilidade espermática e reação acrossomal (coloração tripla - TRI). Após avaliação, estas foram diluídas em meio Tris-gema com 5% de glicerol, envasadas (40x106 espermatozoides/palheta), resfriadas, congeladas e armazenadas em nitrogênio líquido até a análise. Após descongelação, foram submetidas às mesmas avaliações descritas para o sêmen fresco. Não houve interferência da suplementação com Se nas variáveis vigor espermático, HIPO e TRI do sêmen fresco e descongelado. Porém, constatou-se queda na motilidade espermática do GSe comparativamente ao GC no sêmen fresco (P=0,0035) e descongelado (P=0,0067) após 60 dias de suplementação. Portanto, a suplementação de Se na dieta não foi efetiva na promoção de melhorias dos parâmetros espermáticos de touros Brangus.

Abstract The aim of the present study was to evaluate sperm quality of bulls supplemented with selenium (Se) in the diet. Sixteen Brangus bulls were randomly divided in two groups: control (GC) and Se (GSe - 0.1mg Se/kg dietary DM). The experiment lasted 75 days and the animals were supplemented for 60 days. Four semen collections (0, 30, 60 and 75 days) per animal, were performed during the experimental period. Sperm motility and vigor, plasma membrane integrity and functionality (hyposmotic swelling test - HOST) and sperm viability and acrosome reaction (triple staining -TRI) were assessed. After immediate analysis, samples were diluted in Tris-egg yolk extender with 5% glycerol, packed (40x106 spermatozoa / straw), chilled, frozen and stored in liquid nitrogen until analysis. After thawing, sperm motility and vigor, HOST and TRI were performed. No significance was noticed on sperm vigor, HOST and TRI of fresh and post-thawed semen after dietary selenium supplementation. However, sperm motility decreased in GSe compared to GC in fresh (P = 0.0035) and post- thawed (P = 0.0067) semen samples after 60 days of supplementation. Therefore, dietary selenium supplementation was ineffective to improve semen parameters of fresh and post-thawed semen of Brangus bulls.

RESUMO Preparações de enzimas exógenas (atividade fibrolítica (FIB); 0,0; 0,6; 1,2; 1,8 e 2,4 mg/ml do volume de líquido incubado; atividade amilolítica (AMZ); 0,0; 0,05; 0,10; 0,15 e 0,20 mg/ml do volume de líquido incubado; atividade proteolítica (PRO); 0,0; 0,05; 0,10; 0,15 e 0,20 mg/ml do volume de líquido incubado) incubado in vitro. Os efeitos de fermentação foram avaliados com base na produção de gás acumulado, parâmetros cinéticos e, perfil de fermentação usando a técnica de fermentação in vitro. O líquido ruminal foi obtido de dois ovinos Santa Inês canulados no rúmen, alimentados com dieta relação volumoso:concentrado de 20:80. A produção de gás acumulada foi durante 96 h de incubação, mensurados em 18 tempos diferentes. Após a incubação foi avaliado pH, digestibilidade da material seca (DMS), digestibilidade da material orgânica (DMO), energia metabolizável (EM), fator de partição (FP96), rendimento de gás (RG24), ácidos graxos de cadeia curta (AGCC), e produção de proteína microbiana (PPM). O incremento de doses linear de FIB diminuiu (P<0,05) o lag time sem afetar outros parâmetros cinéticos. No entanto, adição de FIB aumentou a produção de gás acumulado, resultando em incremento na DMS, DMO, EM, RG24 e AGCC. A adição de AMZ diminuiu linearmente (P<0,05) lag time e incrementou (P<0,05) produção de gás nos tempos iniciais de incubação sem alterar o perfil de fermentação. A inclusão de PRO não afetou (P>0,05) os parâmetros avaliados. As adições de preparações enzimáticas exógenas com atividades fibrolíticas alteram fermentação ruminal in vitro de dieta de alta níveis de concentrado.

SUMMARY Exogenous enzyme preparations (fibrolytic activity (FIB), 0, 0.6, 1.2, 1.8, and 2.4 mg/ml liquid volume incubated; amylolytic activity (AMZ), 0, 0.05, 0.10, 0.15, and 0.20 mg/ml liquid volume incubated; proteolytic activity (PRO), 0, 0.05, 0.10, 0.15, and 0.20 mg/ml liquid volume incubated) were incubated in vitro. Their fermentation effects were assessed based on accumulated gas production, kinetic parameters, and fermentation profile using the technique of gas fermentation. Ruminal liquid was obtained from two rumen cannulated Santa Inês sheep, fed a diet with roughage-to-concentrate ratio of 20:80. Accumulated gas production was during 96 h of incubation, measured at 18 different times. After incubation, pH, dry matter degradability (DMD), organic matter in vitro digestibility (OMD), metabolisable energy (ME), partitioning factor (PF96), gas yield (GY24), short chain fatty acids (SCFA), and microbial protein production (MCP) were evaluated. Increasing FIB dose linearly decreased (P<0.05) lag time without affecting others kinetic parameters. However, FIB increased the accumulated gas production, resulting in improved DMD, OMD, ME, GY24 and SCFA. The addition of AMZ decreased linearly (P<0.05) lag time and increased (P<0.05) gas production on initial times of incubation without altering the fermentation profile. The inclusion of PRO did not affect (P>0.05) the evaluated parameters. The addition of these exogenous enzyme preparations with fibrolytic activity altered ruminal fermentation in vitro of diets containing high levels of concentrates.

RESUMO Objetivou-se avaliar oito combinações entre três enzimas exógenas fibrolíticas (FIB), amilolíticas (AMZ), e proteolíticas (PRO), sobre a produção acumulada de gás (PG), parâmetros cinéticos e perfil da fermentação simulando dietas de dois sistemas de produção através da técnica de produção de gás in vitro. No experimento 1, o líquido ruminal foi obtido de dois ovinos da raça Santa Inês, canulados no rúmen, mantidos em confinamento, alimentados com dieta com relação volumoso:concentrado 20:80. No experimento 2, o líquido ruminal foi obtido de dois ovinos da raça Santa Inês, canulados no rúmen, mantidos no pasto (Brachiaria brizantha cv. Marandu). A produção de gás acumulada foi obtida em 96 h de incubação, mensurada em 18 horários. Ao final da incubação determinaramse o pH, degradabilidade da matéria seca, digestibilidade in vitro da matéria orgânica, desaparecimento da fibra insolúvel de detergente neutro, energia metabolizável, fator de partição, rendimento de gás, ácidos graxos de cadeia curta, produção de biomassa de proteína microbiana. A fermentação in vitro simulando dietas de confinamento, determinou-se que a participação de enzimas fibrolíticas aumentou PG, e melhorou as características dos parâmetros cinéticos e perfil da fermentação, independente da combinação ou/não com outras enzimas. A fermentação in vitro simulando dietas de forragem, a participação de enzimas fibrolíticas aumentou PG, com melhorias nos parâmetros cinéticos e perfil da fermentação, com ou sem a combinação de outras enzimas. A inclusão apenas de enzimas fibrolíticas tem o maior potencial de otimizar a utilização de dieta de confinamento como também em forragens na alimentação de ruminantes.

SUMMARY This study evaluated the effects of eight combinations of three exogenous enzymes with fibrolytic activity (FIB), amylolytic activity (AMZ), and proteolytic activity (PRO) on the accumulated gas production (PG) and kinetic parameters in simulated fermentations in two diet production systems using the in vitro gas production technique. In experiment 1, ruminal fluid was obtained from two Santa Ines sheep, cannulated in the rumen, kept in a feedlot and fed a diet containing a roughage:concentrate ratio of 20:80. In experiment 2, the ruminal fluid was obtained from two Santa Ines sheep, cannulated in the rumen, and kept on pasture (Brachiaria brizantha cv. Marandu). The accumulated gas production was measured during a 96-hour incubation, measured at 18 different time points. After incubation, the pH, dry matter degradability, organic matter in vitro digestibility, digestibility of neutral detergent insoluble fiber, metabolizable energy, partitioning factor, gas yield, short chain fatty acids and microbial protein production were determined. In the in vitro fermentation using the feedlot diet, the increased use of fibrolytic enzymes increased PG and improved the profile characteristics and kinetic parameters of the fermentation, regardless of the combination with other enzymes. In the in vitro fermentation using the forage diet, increased fibrolytic enzymes also increased PG, with improvements in the kinetic parameters and the profile of the fermentation, independent of the use of the other enzymes. The addition only of fibrolytic enzymes has major potential to optimize the use of feedlot diets as well of forage in ruminant feed.

ABSTRACT The objective of this study was to evaluate the effects of different lipid sources in diets for lactating cows on milk yield and composition, conjugated linoleic acid (CLA) content, and fatty acid profile in the milk fat. Five primiparous Holstein cows were distributed in a 5 × 5 Latin square design. Treatments were: control (no lipid addition) and four other diets containing different lipids sources - ground raw soybean, cottonseed, soybean oil, and calcium salts of soybean fatty acids (CSSFA). The greater milk yield (kg/day) and milk lactose (g/kg) and solids non-fat (g/kg) contents were obtained with the animals fed diets with CSSFA. Regarding the fatty acid profile in the milk fat, the diets with CSSFA and ground raw soybeans produced the greatest concentrations of polyunsaturated fatty acids and C182. Supplementation with CSSFA provided a greater production (g/day) of CLA, resulting in almost twice the values shown by the other treatments. The use of different lipid sources does not affect the milk total solids (protein, fat, and lactose) and CSSFA has a positive influence on the fatty acid profile of the milk fat and amount of CLA produced. Additionally, milk yield is not affected by this supplement.

RESUMO Objetivou-se avaliar o efeito de níveis crescentes de glicerina bruta em suplementos múltiplos, sobre consumo, digestibilidade dos nutrientes, pH, nitrogênio amoniacal ruminal e glicose sérica. Foram utilizados cinco novilhos, Nelore (peso inicial de 480 kg ± 15), em pastejo de forragem tropical, em delineamento experimental Quadrado Latino 5X5. Os tratamentos utilizados foram controle (apenas suplementação mineral) e quatro níveis de glicerina bruta (0, 80, 160, 240 g/kg de suplemento). Não houve influencia do tipo de suplementação (P>0,05) para pH no tempo zero ou quatro horas após a suplementação. Os animais suplementados com níveis de glicerina bruta apresentaram maior N-NH3 (P>0,05) quatro horas após a suplementação, e o consumo de pasto não foi afetado (P>0,05), com incremento no consumo de matéria seca total (P<0,05), devido o aumento da digestibilidade da matéria orgânica (P<0,05). Os suplementos concentrados fornecidos na quantidade de 4 kg por animal a inclusão de glicerina bruta (240 g/kg de suplemento) não altera o consumo de pasto, suplemento e matéria orgânica digerida.

SUMMARY We evaluated the effects of increasing levels of crude glycerin in multiple supplements for grazing beef cattle on intake, nutrient digestibility, pH, ruminal ammoniacal nitrogen, and serum glucose. Five Nellore steers (initial BW of 480 kg [SD 15]), grazing a tropical pasture, were used in a 5 × 5 Latin square design. The treatments used were control (no supplementation; only a mineral mixture ad libitum) and four levels of crude glycerin (0, 80, 160, 240 g/kg of supplements). Supplementation type had no impact (P > 0.05) on pH at 0 and 4 h after supplementation. Animals supplemented with different levels of crude glycerin showed higher N-NH3 values (P < 0.05) at 4 h after supplementation. Crude glycerin supplementation did not reduce pasture intake (P > 0.05), increasing dry matter intake (P > 0.05) due to increased organic matter digestibility (P > 0.05). Supplementation of 4 kg/animal with crude glycerin (240 g/kg supplement) did not reduce pasture intake and organic matter digestibility.

RESUMO O trabalho teve como objetivo avaliar a integridade da membrana plasmática e qualidade seminal de touros suplementados com tocoferol. Foram utilizados 16 touros com idade média de 24 meses e peso médio de 462,2kg, em dois tratamentos: grupo controle (GC) e grupo suplementado com tocoferol (GE- 400 UI de tocoferol/ animal/dia) adicionados ao suplemento concentrado. Os grupos foram mantidos em pastejo com suplementação de 4,5kg/ animal/ dia de concentrado. A suplementação com tocoferol foi fornecida por 60 dias. Foram realizadas 4 coletas de sêmen, sendo: nos dias 0, 30, 60 e 15 dias após o término da suplementação. O sêmen foi coletado por eletroejaculação, aferiu-se as características físicas e morfológicas. Para avaliar a integridade de membrana utilizou-se o teste hiposmótico, coloração eosina/ nigrosina, coloração Pope e trypan blue. Os dados foram analisados através da ANOVA e do teste SNK com um nível de significância de 5%. Foi encontrado efeito da suplementação para vigor (p=0,0183) (GC=2,71±0,095 e GE=2,23±0,16). Não foram encontradas diferenças (p>0,05) para as demais variáveis: volume, motilidade, concentração, morfologia, integridade acrossomal, viabilidade espermática e integridade de membrana. Com os resultados obtidos, nas condições experimentais do presente trabalho, conclui-se que a suplementação oral com tocoferol de 400UI/dia não apresenta melhoria sobre a qualidade seminal nem a integridade da membrana espermática de touros.

SUMMARY This study had objective to evaluate the integrity of the plasma membrane and semen quality of bulls supplemented with tocopherol. Bulls were used 16 with an average age of 24 months and average weight of 462.2 kg in two treatments: control group (CG) and group supplemented with tocopherol (GE-400 IU of tocoferol/animal / day) added to the concentrate supplement. The groups were kept in pasture supplemented with 4.5 kg / animal / day concentrate. Tocopherol supplementation was provided for 60 days. 4 semen samples were carried out: on days 0 , 30, 60 and 15 days after the end of supplementation. Semen was collected by electroejaculation , it has measured up the physical and morphological sperm characteristics. To assess the integrity of membrane used the hyposmotic test, eosin / nigrosine, Pope and trypan blue. The experiment was conducted in a completely randomized design with repeated measurements over time. Data were analyzed using ANOVA and SNK test with a 5% significance level with assistance from the SAS statistical program. It found effect of supplementation force (p = 0.0183) (CG = 2.71 ± 0.095 and GE = 2.23 ± 0.16) ;. There were no differences (p> 0.05) for the other variables: motility, concentration, morphology, acrosome integrity, sperm viability and membrane integrity. With the results obtained in the experimental conditions of this study, it is concluded that oral supplementation with tocopherol 400 IU / day showed no improvement over the seminal quality or integrity of the sperm membrane Bulls.

The objective of this study was to evaluate the performance of F1 (Holstein × Zebu) cows in lactation according to different levels of substitution of soybean meal for a protein equivalent non-protein nitrogen originated from slow-release urea (SRU). Eight F1 (Holstein × Zebu) cows in the first third of lactation, with an average milk yield of 12.7 kg (±3.1 kg)/day and a live weight of 552 kg (±30 kg), were used. The experimental design was composed of two simultaneous 4 × 4 Latin squares, with the following treatments: 100% soybean meal and 0% SRU; 66% soybean meal and 34% SRU; 34% soybean meal and 66% SRU; and 0% soybean meal and 100% SRU. Sorghum silage, used as roughage, was supplied together with the concentrate. Feed intake and digestibility as well as milk yield and milk composition were measured. The obtained data were subjected to analysis of variance, adopting a 5% probability level. No intake variable showed significant differences among the treatments, and the mean values for the intakes of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) were 18.35 2.62 and 5.85 kg/day, respectively. The results for apparent digestibility also did not show differences among treatments, with DM, CP and NDF averaging 58.16, 58.64 and 36.21%, respectively. Milk yield and composition were similar among the treatments. The average 4%-fat-corrected milk yield was 13.39 kg/animal day. Intake, digestibility and milk yield and composition variables are not changed according to the substitution of the soy protein for slow-release urea. Thus, for average-milk-yield crossbred.animals, this substitution depends on economic variables only.

<p>Quarenta e nove novilhos machos foram distribuídos em delineamento casualizado, sendo que inicialmente foram efetuadas sete repetições por tratamento e, ao final do experimento, foram abatidos quatro animais por tratamento. Os tratamentos foram; CONT: Dieta controle; FBC120: Fosfato Bicálcico 120:1 de relação P: F; MBC60: Fosfato monobicálcico 60:1 de relação P:F; FBC30: Fosfato Bicálcico 30:1 de relação P:F; SFT30: Super Fosfato Triplo 30:1 de relação P:F; FBC10: Fosfato Bicálcico 10:1 de relação P:F; CAR10: Concentrado de Rocha 10:1 de relação P:F. A fosfatase alcalina (FA) dos animais aos 650 dias de confinamento, os quais consumiram dieta CAR10, foi maior dos que a FA naqueles que consumiram SFT30 e FBC10 e FBC120. A FA dos animais que consumiram CAR10 foi maior, aos 866 dias, do que àquela observada nos tratamentos com SFT30 e FBC120. O teor de cinza foi maior na dieta FBC10 e as dietas CAR10 e FBC120 representaram o menor valor. O teor de flúor no osso foi maior nos animais da dieta FBC10 em relação àqueles das dietas CAR10, sendo que as dietas FBC120 e MBC60 obtiveram menores teores. A área dos canais de Havers e a relação Havers/área do Osteon foram maiores na dieta FBC30, sendo que o respectivo menor valor foi FBC10. A presença de dentes mosqueados foi superior nos animais tratados com FBC10 e CAR10. Concluiu-se que o alto teor de flúor na dieta aumenta a deposição de flúor nos ossos, o que afeta negativamente nos parâmetros histológicos de dentes e ossos de bovinos de corte.</p>

<p>Forty-nine male calves were allotted in a randomized design, being that initially were performed seven replicates per treatment. At the end of the experiment were slaughtered four animals per treatment. The treatments were designed as following: CONT: control diet; DC120: Dicalcium Phosphate 120:1 ratio P: F; MDCP60: Monodicalcium Phosphate 60:1 ratio P: F; DC30: Dicalcium Phosphate 30:1 ratio P: F; TSP30: Triple Superphosphate 30:1 ratio P: F; DC10: Dicalcium Phosphate 10:1 ratio P: F; PRC10: phosphate rock concentrate of 10:1 of relation P: F. Alkaline phosphatase (ALP) of animals who consumed PRC10 diet was greater than the ALP of animals that consumed TSP30, DC10 and DC120. This result was obtained with animals with 650 days of confinement. The ALP of the animals that consumed PRC10 was greater at 866 days than in the animals consuming TSP30 and DC120 diets. The ash content was greater in the DC10 diet and the diets CAR10 and DC120 achieved the lowest value. The fluorine content in bone was higher in diet DC10, while the diets DC120, PRC10 and MDCP60 obtained the lower values. The area of Haversian canals and the relation Havers/Osteon area were higher in the diet DC30 and the lowest value was encountered in DC10. The mottled teeth were more intensely observed in the treatments DC10 and PRC10. It was concluded that high fluorine content in the diet increases the deposition of fluorine in bones, which negatively affects in the histological parameters of teeth and bones of beef cattle.</p>

The objective was to evaluate intake and digestibility of nutrients, as well as milk production and composition of the milk from F1 Holstein × Gyr cows kept on pasture, supplemented with sugarcane and concentrate (28% CP). Five cows with 150±14 lactation days and average milk production of 7.1±2.1 kg/day were distributed in a 5 × 5 Latin square design. The treatments were: soybean meal-based concentrate; soy bean-based concentrate; ground soybean-based concentrate; roasted soybean-based concentrate; and ground, roasted soybean-based concentrate. Dry matter (DM), organic matter, crude protein (CP), neutral detergent fiber (NDF), total carbohydrates and total digestible nutrients intakes were not affected by the diet, but ether extract intake was higher for the animals fed soy bean-based diets than those fed soybean meal. The digestibility of DM, NDF and CP did not differ. The corrected milk yield differed between treatments; animals on the treatment with soy bean-based concentrate had the lowest production in relation to the others, which did not differ from each other. There was no difference between treatments for milk composition. Thus, soybean meal can be replaced by ground soy beans or roasted soy beans (ground or whole) in diets for low-yield cows reared on Brachiaria decumbens pastures with no harm to milkproduction or composition. Therefore, the use of these alternative raw materials is recommended whenever their inclusion represents lower feeding costs.

The objective of this study was to present some factors affecting feed efficiency in dairy goats. To develop our work, individual and average data from performance experiments with lactating goats were used. The following variables were evaluated: gross feed efficiency, adjusted feed efficiency, dry matter intake, milk-yield, 3.5% fat-corrected milk yield, dry matter digestibility, dietary neutral detergent fiber content, different roughage-to-concentrate ratios and body weight. The statistical analyses involved the application of descriptive and dispersion measures besides Pearson's correlation coefficient and linear regression analysis. The analyzed variables were highly correlated with feed efficiency. The feed efficiency of lactating goats was affected by the milk fat correction, dry matter digestibility, dietary fiber content, proportion of roughage in the diet and body weight. Among these factors, standardization of the milk fat appeared to be the most efficient in correcting the feed efficiency in lactating goats. Correction of some of these factors implies greater precision in the measurement of feed efficiency.

The objective of this study was to evaluate the processing of millet grain provided at two supplementation frequencies for grazing beef cattle during the dry season on nutritional parameters. Five rumen-cannulated crossbred steers, with 24 to 26 months of age and average body weight of 428.6±26.06 kg, were assigned to a Latin square design (5 × 5) in a 2 × 2 + 1 factorial arrangement, as follows: two forms of millet grain (whole grains - or ground; WG - GG), two strategies of concentrate supplementation (daily distribution - 7X; or three times a week - 3X) and a control treatment (mineral mixture - MM). Animals were kept in five paddocks of 0.24 ha each with Marandu grass pastures. Concentrate supplements were supplied at 2.00 and 4.66 kg/animal/day for treatments 7X and 3X, respectively. The concentrate supplementation enhanced the intake of total dry matter (DM) and organic matter (OM) and nutrients compared with mineral supplementation. No differences were found between dry matter intake and forage organic matter intake. The values of digestibility coefficients of DM, OM, ether extract, total carbohydrates and non-fiber carbohydrates were increased by concentrate supplementation. Regarding concentrations of rumen ammonia nitrogen, the interactions among time × treatment × day and day × treatment had effects on the measurements of ruminal pH. Plasma urea nitrogen, urinary urea excretion and urinary urea N excretion differed only between MM treatment and the others, with no interference of grain physical form and supplementation frequency on those variables. The millet grain processing does not alter forage intake, but improves digestibility. Daily supplementation increases digestibility of dry matter and neutral detergent fiber.

The objective of this study was to evaluate the effect of five nitrogen doses on the productive and quality characteristics and the use efficiency of Brachiaria brizanthacv. Marandu grass. The treatments consisted of four doses of nitrogen (0, 60, 120, 180 and 240 kg ha-1), distributed through a completely randomized design with four replicates. Samples of the material were collected to analyze productivity variables, concentrations of neutral detergent fiber, crude protein and neutral detergent insoluble nitrogen, and in vitro dry matter digestibility. The nitrogen use efficiency, recovery of the applied nitrogen (RAN) and agronomic efficiency of the applied nitrogen (AE) were calculated. Dry mass production increased by 1,624.67 (kg/ha) as the nitrogen doses were increased. The doses of nitrogen affected the concentrations of neutral detergent fiber (from 294.6 to 381.4 g.kg-1, in the leaf), crude protein (from 86.1 to 99.6 g.kg-1, in the leaf) and neutral detergent insoluble protein (from 402.9 to 396.2 g.kg-1 CP, in the leaf). Nitrogen use efficiency increased, whereas RAN and AE were not affected by the nitrogen doses. Nitrogen fertilization promotes improvement in productivity and chemical composition of Marandu grass, also improving the efficiency with which the grass utilizes the nitrogen.

The objective of this study was to evaluate the effects of total digestible nutrient (TDN) levels in supplements on rumen pH, ruminal ammonia nitrogen concentration, intake and digestibility, nitrogen balance and microbial efficiency in beef cattle grazing on Marandu grass during the rainy season. The supplements comprised a mineral mixture, ground corn grain, soybean hulls, roasted soybeans and urea:ammonium sulfate. The mineral mix (MM) and supplements were supplied at 800, 1,600 and 2,400 g/animal/day, contained 500, 1,000 and 1,500 g of TDN, respectively, and were termed S500, S1000 and S1500. Supplemental crude protein (CP) was fixed at 300g animal/day for all supplementing strategies. Four crossbred rumen-fistulated steers, with an average weight of 512kg, were utilized. The animals were distributed in a 4×4 Latin square in four paddocks of 0.25 ha. The rumen nitrogen concentration was increased by 63% after four hours of supplementation. Supplements with increased TDN levels did not alter the total dry matter and forage intakes, although the TDN levels linearly increased the non-fibrous carbohydrates intake. Additionally, most supplements did not alter the digestibility of the diet nutrients.The nitrogen balance was similar in all treatments. However, supplements with the highest TDN levels linearly improved the microbial efficiency of finishing beef cattle that were pasture-grazed during the rainy season. Supplements with in creasing TDN levels improve the microbial efficiency during the rainy season.

O objetivo deste trabalho foi avaliar o efeito da substituição parcial do milho por fontes energéticas alternativas, em suplementos concentrados para bovinos de corte mantidos em pasto de Urochloa brizantha cultivar Marandu, durante o período das águas, no consumo e na digestibilidade aparente total dos alimentos. Foram utilizados cinco bovinos Nelore com peso médio corporal inicial de 367,8±4,31 kg. Utilizou-se o delineamento experimental quadrado latino 5x5, com cinco animais e cinco tratamentos. Foram avaliados: suplementos concentrados isoproteicos, com 30% de proteína bruta, formulados à base de grãos de milho, de milheto e de sorgo, e casca de soja; e um suplemento mineral (controle). Não foram observadas diferenças significativas no consumo de matéria seca (MS) total e de matéria orgânica (MO) entre os animais que receberam suplementação mineral e os que receberam suplementação concentrada; no entanto, estes últimos apresentaram menor (12,28%) consumo de MS de pasto. A suplementação concentrada aumentou o coeficiente de digestibilidade aparente total da MS, da MO, da proteína bruta e dos carboidratos não fibrosos que não foram influenciados pelas fontes de energia. Os grãos de milheto e de sorgo e a casca de soja podem ser utilizados em substituição parcial ao milho, na formulação de suplementos concentrados, sem prejudicar o consumo e a digestibilidade dos nutrientes da dieta.

The objective of this work was to evaluate the effect of the partial replacement of corn by alternative energy sources in concentrate supplements for beef cattle kept on Urochloa brizantha cultivar Marandu pasture, during the rainy season, on feed intake and total apparent digestibility. Five Nellore cattle with initial average body weight of 367.8±4.31 kg were used. The experimental design was a 5x5 Latin square, with five animals and five treatments. The following were evaluated: isoproteic concentrate supplements, at 30% crude protein, formulated with corn, millet, and sorghum grains, and soybean hulls; and a mineral supplement (control). No significant differences were observed in total dry matter (DM) and organic matter (OM) intake between the animals fed mineral supplementation and those receiving concentrate supplementation; however, the latter showed the lowest (12.28%) pasture DM intake. Concentrate supplementation increased the coefficient of total apparent digestibility of DM, OM, crude protein, and of non-fiber carbohydrates that were not affected by the energy sources. Millet and sorghum grains, and soybean hulls can be used to partially replace corn in the formulation of concentrate supplements without affecting intake and digestibility of dietary nutrients.