ABSTRACT: In Brazil, urea is the most used nitrogen (N) fertilizer to improve forage production. However, their excessive use can cause environmental impacts through N losses, such as ammonia (NH3) volatilization. Therefore, the current study adjusted and estimated the NH3 volatilization from urea applied on tropical pastures in three rainfall conditions using mathematical models. Data were collected from Marandu grass (Brachiaria brizantha) fertilized with 50 kg N ha-1 during wet, intermediate, and dry conditions. Ammonia volatilization was measured in five semi-open chambers for 21 days. The linear, quadratic, exponential, Gompertz, Groot, and Richards models were tested for fitting and estimating the NH3 volatilization. The Gompertz, Groot, and Richards models generated predictions similar to the observed data, with a high determination coefficient, indicating a better fit of these equations to data, with precision and accuracy. However, the Groot model was selected due to the lowest root mean square error of prediction (0.29 % total N lost as NH3). The greatest N loss as NH3 volatilization occurred in the wet, followed by intermediate and dry conditions (20.2, 17.0, and 11.3 % total N lost as NH3, respectively). Therefore, nitrogen losses as NH3 volatilization after application of 50 kg N ha-1, as urea source, are altered according to the weather conditions, reaching 20% of N added in the wet rainfall period. The Groot model is recommended for fitting and estimating the NH3 volatilization from urea applied on Marandu grass pastures in the wet and dry rainfall conditions.

RESUMO: No Brasil, a ureia é o fertilizante nitrogenado mais utilizado para melhorar a produção de forragem. No entanto, seu uso excessivo pode causar impactos ambientais por meio de perdas de nitrogênio (N), como a volatilização da amônia (NH3). Portanto, o objetivo do presente estudo foi ajustar a volatilização de NH3 da ureia aplicada em pastos tropicais em três condições de chuva utilizando modelos matemáticos. Dados foram coletados de pastos de capim-marandu (Brachiaria brizantha) adubado com 50 kg N ha-1 em condições úmidas, intermediárias e secas. A volatilização da NH3 foi medida em cinco câmaras semiabertas durante 21 dias. Os modelos, linear, quadrático, exponencial, Gompertz, Groot e Richards foram testados para ajuste e estimativa da volatilização do NH3. Os modelos de Gompertz, Groot e Richards geraram predições semelhantes aos dados observados, com alto coeficiente de determinação, indicando um melhor ajuste dessas equações aos dados, com acurácia e precisão. No entanto, o modelo Groot foi selecionado devido ao menor erro quadrático médio das predições (0,29% de N total perdido como NH3). A maior volatilização de NH3 ocorreu em condições climáticas úmida, seguido por intermediária e seca (20,2; 17,0 e 11,3% de N total perdido como NH3, respectivamente). Portanto, as perdas de N como volatilização de NH3 após a aplicação de 50 kg N ha-1, como fonte de ureia, são alteradas de acordo com as condições climáticas, atingindo a 20% do N adicionado nas condições úmidas. O modelo Groot é recomendado para ajuste e estimativa da volatilização de NH3 da ureia aplicada em pastos de capim Marandu em condições úmidas e secas.

Resumen El pasto Panicum maximum cv. BRS Tamani es una planta forrajera híbrida de alta calidad, de tamaño pequeño y con intensa actividad de macollaje. Este estudio se llevó a cabo para examinar el potencial del pasto Panicum maximum cv. BRS Tamani en diferentes edades de rebrote (49, 63, 77 y 91 días) para la producción de heno, en el período lluvioso. El experimento se realizó en la Escuela Agrícola de la Universidad Federal de Mato Grosso do Sul-Brasil, entre octubre de 2015 y abril de 2016. Los tratamientos correspondieron a cuatro edades de rebrote, con cuatro repeticiones, distribuidas en parcelas de 9 m2. Las edades de rebrote influyeron en las características morfogenéticas del pasto, excepto por la senescencia de la hoja y la longitud final de la hoja. Los rendimientos de materia verde (9.6-17.6 t ha-1) y seca (2.6-5.9 t ha-1), el rendimiento de heno (3.4-6.9 t ha-1) y las proporciones de tallo (91.6-455.9 g kg-1) y material senescente (34.8-98.4 g kg-1) aumentaron con las edades de rebrote, mientras que la proporción de hojas (837.7-402.1 g kg-1) y la relación hoja:tallo (15.9-0.9) disminuyeron (P<0.05). Los contenidos de materia seca (881.7-852.8 g kg-1) y de proteína (81.2-47.6 g kg-1) del heno disminuyeron con las mayores edades de rebrote; sin embargo, los contenidos de fibra detergente neutro (746.5-759.2 g kg-1), fibra detergente ácido (519.8-567.7 g kg-1) y lignina (74.3-86.4 g kg-1) aumentaron a medida que lo hicieron las edades de rebrote. La digestibilidad de los nutrientes disminuyó con las edades de rebrote (P<0.05). Panicum maximum cv. BRS Tamani tiene el potencial de producir heno ha-1, mejor valor nutritivo y una alta proporción de hojas en el intervalo de rebrote de 49 a 63 días.

Abstract The grass Panicum maximum cv. BRS Tamani is a hybrid high-quality, small-sized forage plant with intense tillering activity. This study was carried out to examine the potential of the grass Panicum maximum cv. BRS Tamani at different regrowth ages (49, 63, 77, and 91 d) for hay production, in the rainy period. The experiment was conducted at the Farm School of the Federal University of Mato Grosso do Sul-Brazil, between October 2015 and April 2016. The treatments corresponded to four regrowth ages, with four replicates, distributed into 9 m2 plots. Regrowth ages influenced the morphogenetic characteristics of the grass, except for leaf senescence and final leaf length. Green (9.6-17.6 t ha-1) and dry-matter (2.6-5.9 t ha-1) yields, hay yield (3.4-6.9 t ha-1), and proportions of stem (91.6-455.9 g kg-1) and senescent material (34.8-98.4 g kg-1) increased with the regrowth ages, while the proportion of leaves (837.7-402.1 g kg-1) and the leaf: stem ratio (15.9-0.9) decreased (P<0.05). The dry matter (881.7-852.8 g kg-1) and protein contents (81.2-47.6 g kg-1) of the hay decreased with the higher regrowth ages; however, the neutral detergent fibre (746.5-759.2 g kg-1) acid detergent fibre (519.8-567.7 g kg-1) and lignin (74.3-86.4 g kg-1) contents rose as the regrowth ages did. Nutrient digestibility decreased with the regrowth ages (P<0.05). Panicum maximum cv. BRS Tamani has the potential to produce of hay ha-1, better nutritive value and a high proportion of leaves in the regrowth interval of 49 to 63 d.

Abstract Sheep production systems face numerous challenges, which make decision-making a process fraught with risks and uncertainties. Modelling is a helpful tool in this respect, as it allows decision-makers to evaluate the behaviour of variables and their interrelationships, in addition to using previous or related information to predict results and simulate different scenarios. The advent of prediction models has made it possible to monitor the weight of an animal and determine the best time for its sale. Additionally, it allows producers to estimate the weights of the carcass and major marketable cuts before slaughter. All this information is directly associated with the profitability and success of the production activity. Therefore, in view of the different applications of mathematical models in production systems, this literature review examines concepts in modelling studies and the importance of using prediction models in meat sheep production. Furthermore, it addresses the practical application of modelling studies in predicting dry matter intake and carcass traits of meat sheep through correlated variables.

Resumen Los sistemas de producción ovina se enfrentan a numerosos desafíos, que hacen de la toma de decisiones un proceso lleno de riesgos e incertidumbres. En este sentido, la modelación es una herramienta útil, ya que permite a los tomadores de decisiones evaluar el comportamiento de las variables y sus interrelaciones, además de utilizar información previa o relacionada para predecir resultados y simular diferentes escenarios. El advenimiento de los modelos de predicción ha permitido monitorear el peso de un animal y determinar el mejor momento para su venta. Además, permite a los productores estimar los pesos de la canal y los principales cortes comercializables antes del sacrificio. Toda esta información está directamente asociada a la rentabilidad y el éxito de la actividad productiva. Por lo tanto, en vista de las diferentes aplicaciones de los modelos matemáticos en los sistemas de producción, esta revisión de la literatura examina los conceptos en los estudios de modelación y la importancia de utilizar modelos de predicción en la producción de ovinos de carne. Además, aborda la aplicación práctica de los estudios de modelación en la predicción de la ingesta de materia seca y los rasgos de la canal de ovinos de carne a través de variables correlacionadas.

ABSTRACT The effects of diets containing oilseeds were measured to evaluate the productive and economic parameters in the finishing of young, feedlot Nellore bulls. Twenty-four young Nellore bulls were used, with an initial body weight (BW) of 311.46±0.37 kg and 24 months of age, distributed into individual stalls ( 4 × 20 m) in a completely randomized design, totaling four treatments with six repetitions per treatment. Four diets (control, based on corn and soybean meal, and three diets containing cottonseed, soybean, and sunflower) were evaluated. Feed and orts were measured daily to calculate intake and costs. The dry matter intake of the control group was higher than soybean (10.64 kg/day), cotton (9.88 kg/day), and sunflower (9.30 kg/day) treatments, respectively. The cottonseed treatment showed the highest average neutral detergent fiber intake. There was a dietary effect of diets on average daily gain, total weight gain, and final weight. The soybean treatment showed the highest performance, total gain (232.55 kg), and final weight (544.38 kg). Oilseed intake can modify the fatty acids profile in the meat, decreasing its saturated fatty acid content. Whole soybean seed favors performance, improves feed efficiency, fatty acid profile, and fat distribution in the carcass, and can reduce production costs.

ABSTRACT The objective was to examine the effect of two short-term protein-energy supplementation (STPES) strategies at the rearing phase on the performance of Nellore calves grazing on Mombaça or Marandu grasses. The experiment used 72 calves (7-mo old, 229±3.0 kg body weight [BW]) allotted in a completely randomized block design to four treatments in a 2 × 2 factorial arrangement: two forage cultivars (Panicum maximum cv. Mombaça vs. Brachiaria brizantha cv. Marandu) and two STPES (WEAN – STPES immediately after weaning vs. TRAN – STPES in the transition of dry-rainy). The WEAN animals received 1 kg day−1 (n = 36) of a protein-energy supplement, whereas TRAN animals were subjected to STPES at 2 g/kg BW day−1 (n = 36), both for 53 days. Every 28 days, calves were weighed to measure performance, and pastures were sampled to evaluate productive and structural traits. Growth performance was analyzed considering a completely randomized block design with a 2 × 2 arrangement of treatment, whereas forage responses included repeated measures. Marandu had a higher forage mass (3,586 kg) than Mombaça (2,890 kg), but there was no difference in forage mass in each cultivar between preconditioning periods. The nutritional composition of Marandu and Mombaça cultivars did not differ and had similar results of in vitro fermentation variables. Stocking rate was higher for WEAN, in the Mombaça pastures. The STPES at weaning on Marandu provided greater gains per area. When applied in the period following the weaning and coinciding with the dry season, the STPES improves the performance of newly weaned calves kept on Marandu and Mombaça grasses.

Abstract This study was carried out to evaluate the time for the establishment of tropical forage grasses in the “Cerrado” biome, based on morphogenetic and structural traits. Three Brachiaria brizantha (Syn. Urochloa brizantha) cultivars (Paiaguás, Ipyporã and Marandu) and two Panicum maximum (Syn. Megathyrsus maximus) cultivars (Quênia and Tamani) were distributed in a randomized-block design with four replicates. Morphogenetic and structural traits of the pasture were assessed from d 35 to d 65 after sowing, at seven-day interval. Canopy height rose linearly with the establishment period, in all cultivars. In the Megathyrsus cultivars, tiller density decreased as the experimental period progressed, whereas the number of tillers in the Urochloa cultivars increased. The cultivars Ipyporã and Marandu had the highest leaf appearance rates. The lowest leaf elongation rates occurred in the cultivars Paiaguás, Ipyporã and Tamani, and the highest elongation rates in cv. Quênia. As a result, cv. Quênia showed the highest values of final leaf length (64.9 cm) and leaf blade mass (3,352.9 kg DM ha-1). The higher senescence rate of cv. Tamani (2.1 cm tiller-1 d-1) resulted in the highest percentage of dead material (1,815.5 kg ha-1) being found in the herbage mass of this cultivar. Cultivars Paiaguás, Marandu and Tamani were established at 44 d, whereas cv. Quênia and Ipyporã were established at 51 and 58 d after sowing, respectively, in the Brazilian Cerrado.

Resumen Este estudio se llevó a cabo para evaluar el tiempo para el establecimiento de gramíneas forrajeras tropicales en el bioma del “Cerrado”, con base en rasgos morfogenéticos y estructurales. Se distribuyeron tres cultivares (Paiaguás, Ipyporã y Marandu) de Brachiaria brizantha (Sin. Urochloa brizantha) y dos cultivares (Quênia y Tamani) de Panicum maximum (Sin. Megathyrsus maximus) en un diseño de bloques al azar con cuatro repeticiones. Los rasgos morfogenéticos y estructurales del pasto se evaluaron desde el día 35 hasta el día 65 después de la siembra, a intervalos de siete días. La altura del dosel aumentó linealmente con el período de establecimiento, en todos los cultivares. En los cultivares de Megathyrsus, la densidad de macollos disminuyó a medida que avanzaba el período experimental, mientras que el número de macollos en los cultivares de Urochloa aumentó. Los cultivares Ipyporã y Marandu tuvieron las tasas más altas de aparición foliar. Las tasas de elongación foliar más bajas se presentaron en los cultivares Paiaguás, Ipyporã y Tamani, y las tasas de elongación más altas en el cv. Quênia. Como resultado, el cv. Quênia mostró los valores más altos de longitud foliar final (64.9 cm) y masa de lámina foliar (3,352.9 kg MS ha-1). La mayor tasa de senescencia del cv. Tamani (2.1 cm macollo-1 d-1) dio como resultado que el mayor porcentaje de material muerto (1,815.5 kg ha-1) se encontrara en la masa de forraje de este cultivar. Los cultivares Paiaguás, Marandu y Tamani se establecieron a los 44 d, mientras que los cv. Quênia e Ipyporã se establecieron a los 51 y 58 días después de la siembra, respectivamente, en el Cerrado brasileño.

RESUMO: O objetivo foi avaliar os efeitos das doses anuais de 100 e 200 kg ha-1 de nitrogênio (N) sobre as características morfogênicas e estruturais do capim-ipyporã, em lotação intermitente durante as estações do ano. O delineamento experimental foi em blocos ao acaso, com dois tratamentos e três repetições de área. Os pastos de capim-ipyporã foram submetidos ao pastejo por bovinos de corte. Foram avaliadas as características morfogênicas e estruturais do dossel forrageiro por meio da técnica de perfilhos marcados. Também foi avaliado o acúmulo de forragem e a densidade populacional de perfilhos (DPP). Foi observada interação significativa (P < 0,05) das doses de N e estações do ano para o período de descanso (PD), duração de vida das folhas (DVF), filocrono, taxa de alongamento de colmos (TAlC) e comprimento final das folhas (CFF). Durante o inverno, o PD foi menor (40 vs 50 dias) nos pastos adubados com 200 kg ha-1 de N. Em contra partida, no inverno, os pastos adubados com 100 kg ha-1 de N apresentaram maiores valores para DVF, filocrono e TAlC, e menores para o CFF. Não foi observado efeito isolado de doses de N (P > 0,05) para as taxas de acúmulo de forragem; de aparecimento, alongamento e de senescência de folhas, relação folha:colmo e para a DPP. No entanto, o efeito das estações foi significativo para estas variáveis, com os maiores valores observados durante a primavera e verão. O uso de 200 kg ha-1 de N para pastos de capim-ipyporã promove redução da estacionalidade de produção da forrageira.

ABSTRACT: This study examined the effects of annual nitrogen (N) rates of 100 and 200 kg ha-1 on the morphogenetic and structural traits of Ipyporã grass (Brachiaria brizantha × Brachiaria ruziziensis) under intermittent grazing during the seasons of the year. The experiment was laid out in a randomized-block design with two treatments and three area replicates. Ipyporã grass pastures were grazed by beef cattle. Morphogenetic and structural traits of the forage canopy were evaluated using the marked-tiller technique. Forage accumulation and tiller density (TD) were also evaluated. Significant interaction effects (P < 0.05) between N rates and seasons were observed for the rest period, leaf lifespan (LLS), phyllochron, stem elongation rate (SER) and final leaf length (FLL). During winter, the rest period was shorter (40 vs. 50 days) in the pastures fertilized with 200 kg ha-1 N. Conversely, in winter, the pastures fertilized with 100 kg ha-1 N showed higher LLS, SER and phyllochron values, but lower FLL values. There was no isolated effect of N rates (P > 0.05) on forage accumulation rate; leaf appearance, elongation or senescence rates; leaf:stem ratio; or TD. However, the effect of seasons was significant for these variables, with the highest values occurring during spring and summer. The use of 200 kg ha-1 N in Ipyporã grass pastures reduces the seasonality of forage production.

ABSTRACT. The present study aimed to evaluate the residual effects of the application of biofertilizer and mineral fertilizer on sward structure and morphological components of Panicum maximum cv. Massai. The experimental design comprised randomized blocks with six treatments consisting of increasing doses of swine biofertilizer (0, 10, 20, 30 and 40 Mg ha-1) and mineral fertilization (150 kg N ha-1, 33 kg P ha-1), with four replicates. The variables analyzed were pasture height, light interception, leaf area index, forage mass and morphological components. Plant height responded linearly and positively to biofertilizer levels in the three evaluations. The highest averages for light interception (51.63%) and leaf area index (1.64) were observed for the 240 days (40 Mg ha-1). Dry leaf mass was influenced by the increase in biofertilizer dose, with increments of 39.68%, 25.07% and 44.66% for the 240, 300 and 360 days, respectively, when compared to the control treatment. Mineral fertilization promoted lower mass of dead material and lower leaf area index but did not differ from biofertilizer for the other variables. The residual effect of swine biofertilizer was greater than that of mineral fertilization, with a minimum use of 20 Mg ha-1 a practical agronomic recommendation.

Abstract We hypothesize that lambs fed diets with different lipids sources from oilseeds would similar performance but fatty acids profile of meat superior to those fed with conventional diets. We evaluated the effects of inclusion of oilseeds on the ingestive behaviour, performance, carcass trait and meat quality in feedlot lambs. Three isonitrogenous (18.31% crude protein) diets were evaluated, where one diet was the standard (control), and the others two diets contained soybean and cottonseed. Fifteen Texel lambs, weighting 28.5 ± 1.65 kg were distributed in a completely randomized design by 56 days. Animals fed soybean diet demonstrated greater final body weight when compared to animals fed cottonseed diet and standard diet. The inclusion of cottonseed provided lower average daily gain and total weight gain. Ingestive behaviour of the animals fed diets with grains resulted in greater rumination time. Lambs fed cottonseed diet spent greater time during rumination and presented greater number of chews/day. The hot carcass and cold carcass weight presented lower values in animals fed cottonseeds diet. There was no significant difference in meat for marbling, maturity, fat texture and shear force. Meat from animals fed soybean diet had highest fat content. There was a diet effect for fatty acids composition in the meat. Meat of lambs treated with soybean have greater amounts for fatty acids mostly the unsaturated ones, related to the decrease in cholesterol levels, and lower risk of cardiovascular diseases, thus, lambs fed soybean enrich meat produced with fatty acids that benefit human health.

RESUMO: Este trabalho teve como objetivo avaliar o efeito da calagem (com e sem) e do biocarvão (com e sem) sobre o crescimento e a produção de forragem do sorgo forrageiro cv. BRS Ponta Negra e nas propriedades químicas do Neossolo Quartzarênico no ambiente Semiárido. O delineamento experimental foi em blocos casualizados, com tratamentos em esquema fatorial 2x2, correspondendo a aplicação ou não do calcário (0 e 2,5 t ha-1) e do biocarvão (0 e 12,5 t ha-1). O biochar era produzido a partir de galhos de caju. O experimento foi conduzido em parcelas de 16 m² onde foi cultivada a cultivar de sorgo forrageiro BRS Ponta Negra. Foram avaliadas as características químicas do solo, os atributos de produção e as características estruturais da cultivar de sorgo estudada. Não houve interação entre os fatores. O uso do biochar aumentou o pH e os teores de Ca e P no solo e contribuiu para o aumento da massa da panícula (2,51 t ha-1 de MS). A aplicação de calcário afetou o teor de Ca no solo, assim a dose de 2,5 t ha-1 resultou em maiores valores de diâmetro do colmo (15,25 mm), massa da panícula e massa do colmo (2,63 e 7,50 t ha-1 de MS, respectivamente). Portanto, esses resultados permitem traçar estrategias de uso do calcário e biochar para produção forrageira em ambientes semiáridos com solos arenosos. Pois, esses materias melhoram alguns atributos quimicos do solo e a produção do sorgo forrageiro. Vale ressaltar que as condições edofoclimáticas podem alterar os padrões de resposta observados nesta pesquisa. Portanto, a pesquisa em outras regiões é essencial.

ABSTRACT: This research evaluated the effect of liming (with and without) and biochar (with and without) on sorghum cv. BRS Ponta Negra growth and Arenosol chemical properties in the Semiarid environment. The experimental design was in randomized blocks, with treatments in a 2x2 factorial scheme, corresponding to the application or not of lime (0 and 2.5 t ha-1) and biochar (0 and 12.5 t ha-1). Biochar was produced from cashew branches. The experiment was conducted in 16 m² plots where the forage sorghum cultivar BRS Ponta Negra was cultivated. The soil chemical characteristics, the production attributes, and the structural characteristics of the sorghum cultivar studied were evaluated. There was no interaction between factors. The use of biochar increased the pH and Ca and P contents in the soil and contributed to increasing the panicle mass (2.51 t ha-1 of DM). Lime application affected the soil Ca content as the dose of 2.5 t ha-1 resulted in higher values of culm diameter (15.25 mm), panicle mass, and culm mass (2.63 and 7.50 t ha-1 of DM, respectively). Therefore, these results allowed to outline strategies for the use of limestone and biochar for forage production in semiarid environments in sandy soils. Because, these materials improve some chemical attributes of the soil and the production of forage sorghum. It is noteworthy that edophoclimatic conditions can change the response patterns observed in this research. Therefore, research in other regions is essential.

Abstract Thirty-two Santa Inês male lambs, not castrated, were distributed in a randomized block design to evaluate the effects of different tropical forage cultivars (two Panicum maximum (Syn. Megathyrsus maximus): Aruana and Massai, and two Brachiaria brizantha (Syn. Urochloa brizantha) Marandu and Piatã) on carcass characteristics, quality, physical composition, and meat chemistry. The data were subjected to an analysis of variance, and the means compared using the Tukey test at 5% significance. There was no effect of cultivars on body weight, slaughter weight, and biometric measurements of the carcass. The Aruana and Piatã cultivars provided higher weights of hot and cold carcasses when compared to the Massai and the Marandu had no significant differences compared to the others. The animals kept in the pasture of the Aruana cultivar showed higher shank yields. However, forage cultivars did not affect the ribeye area or subcutaneous fat thickness. There was also no effect of cultivar on pH, temperature, cooking losses, cooling losses, and meat shear strength. The cultivars did not change the quality and composition of the meat. However, the Aruana, Piatã, and Marandu cultivars were the ones that provided higher carcass weights and ham yields.

Abstract Our hypothesis was that different sources of unsaturated fatty acids from oilseeds (sunflower, soybeans, and cottonseed) could alter milk yield, fatty acid profile, and the amount of unsaturated fatty acids yielded in milk. It aimed to evaluate the effects of lipid sources on yield and composition and fatty acids in milk of primiparous Girolando cows. Five cows in lactation (35 ± 8 days), with 410 ± 7.15 kg BW were randomly distributed in a 5 x 5 Latin square. Five experimental diets, namely a control diet without an additional source of lipid and four diets with different lipid sources: cottonseed, sunflower seed, whole soybean, or soybean oil, as lipid source, to reach 70 g/kg of ethereal extract dry matter basis were used. Cottonseed and soybean oil addition reduced daily yield by 15 and 22%. Oilseed can alter fatty acid profile in milk. Whole soybean provided greater daily milk and fatty acids yields.

ABSTRACT This study examined the effect of different supplementation strategies for ewes in the last third of gestation, kept on a deferred Brachiaria brizantha cv. Marandu pasture, on their performance and the growth curve of their lambs. A total of 54 ewes, of no defined breed, with an average weight of 41.10±3.10 kg, were used in a completely randomized design, divided into three groups (18 ewes per treatment). In total, 61 lambs were born, 28 females and 33 males, with 3.70±0.55 and 3.68±0.69 kg birth weight, respectively. Treatments were as follows: multiple mixture ad libitum, concentrate supplement at 0.4% live weight (LW), and concentrate supplement at 0.8% LW. Average daily weight gain (ADG, g/animal/day) and total weight gain (TWG, kg/animal) were evaluated in ewes and lambs. Reproductive efficiency indices were measured in the ewes and biometric variables in the lambs. The ADG and TWG of ewes in the last third of gestation were higher in animals supplemented at 0.8% LW. Reproductive efficiency results were superior in ewes supplemented at 0.4% LW. The effect of ewe supplementation on lamb growth curve as estimated by the Gompertz model did not reveal differences between the curves of lambs born to ewes that received supplementation at 0.4 and 0.8% LW. However, supplementing ewes with a multiple mixture induced a reduction in the growth curve parameters of their lambs. The use of concentrated supplementation, at levels of 0.4 and 0.8% of LW, provides greater productive and reproductive performance for ewes and lambs.

Resumen Este trabajo tuvo como objetivo evaluar los efectos de tres dosis de nitrógeno (N) en las características morfogénicas y estructurales, la masa (MR) y la distribución de las raíces en el perfil del suelo, y la resistencia del suelo a la penetración de las pasturas de guinea Mombasa manejados con pastoreo rotacional. El diseño experimental utilizó bloques al azar con tres dosis de N (100, 200 y 300 kg ha-1) y tres repeticiones. El criterio para interrumpir el rebrote de los pastos fue la altura de 80 a 90 cm del dosel (90-95 % de intercepción de luz por el dosel). Los animales fueron retirados de los potreros cuando el dosel alcanzó el 50 % de la altura prepastoreo. Se evaluó la masa y acumulación del forraje, las características morfogénicas y estructurales del dosel, la MR y distribución en el perfil del suelo, y la resistencia del suelo a la penetración. En pastos fertilizados con 200 y 300 kg ha-1 de N, se observó la mayor aparición foliar (0.090 hojas macollo-1 día-1 y 0.081 hojas macollo-1 día-1), tasas de alargamiento (2.82 y 2.61 cm macollo-1 d-1) y mayor acumulación diaria de forraje (113.8 y 106.6 kg ha-1d-1). El uso de 300 kg ha-1 de N promovió una mayor resistencia del suelo a la penetración a 10 cm de profundidad en el pospastoreo (3.3 MPa). No se observó ningún efecto de las dosis de N en la MR (P>0.05). Por lo tanto, el control de la altura antes y después del pastoreo de los animales en los potreros ayudó a mantener la estructura del pasto y evitar el proceso de compactación del suelo. De acuerdo con los resultados, se concluye que 200 y 300 kg ha-1 de fertilización con N es una estrategia para intensificar los pastos.

Abstract This work aimed to evaluate the effects of three nitrogen (N) doses on the morphogenic and structural characteristics, root mass (RM) and distribution in the soil profile, and penetration soil resistance of Mombasa guineagrass pastures managed with rotational stocking. The experimental design used randomized blocks with three N doses (100, 200, and 300 kg ha-1) and three replicates. The criterion for interrupting the pastures’ regrowth was the height of 80 to 90 cm of the canopy (90-95 % of light interception by the canopy). The animals were removed from the paddocks when the canopy reached 50 % of the pre-grazing height. Forage mass and accumulation, canopy morphogenic and structural characteristics, RM and distribution in the soil profile, and soil resistance to penetration were evaluated. In pastures fertilized with 200 and 300 kg ha-1 of N, the highest leaf appearance (0.090 and 0.081 leaves-1 tiller-1 d-1), elongation rates (2.82 and 2.61 cm tiller-1 d-1) and highest daily forage accumulation (113.8 and 106.6 kg ha-1d-1) were observed. Using 300 kg ha-1 of N promoted greater soil resistance to penetration at 10 cm of depth in the post-grazing (3.3 MPa). No effect of N doses was observed for RM (P>0.05). The pre- and post-grazing height control of animals in the paddocks therefore helped to maintain the pasture structure and avoid the soil compaction process. According to the results, it is concluded that 200 and 300 kg ha-1 of N fertilization is a strategy for intensifying pastures.

Resumen Se planteó la hipótesis de que es posible que el inóculo de diferentes especies de rumiantes con capacidades digestivas diferentes que se alimentan de un determinado forraje puede mostrar diferentes utilizaciones de alimento en comparación con otras especies de rumiantes. Se evaluaron cinco gramíneas Brachiaria: B. decumbens cv. Basilisk, B. decumbens acceso D70, B. humidicola cv. Tupi, B. humidicola cv. Común, y B. ruziziensis acceso R124, en dos edades de rebrote (21 y 42 d). Se analizó la producción, el contenido bromatológico, la digestibilidad de materia seca in vitro (DMSiv) y la digestibilidad de la fibra detergente neutro in vitro (DFDNiv) utilizando inóculos bovinos u ovinos. El experimento utilizó un diseño factorial de 5 × 2 × 2 y encontró efectos significativos para la variedad de gramínea y la edad de rebrote. Además, se encontraron interacciones significativas de gramínea × edad en la materia seca, la proteína cruda, la fibra detergente neutro y la fibra detergente ácido de la muestra total y lamina de la hoja. Hubo un efecto significativo de la variedad de gramínea y la edad de la gramínea en la masa del forraje, la relación lámina de la hoja/tallo, lámina de la hoja, tallo, material senescente y crecimiento. En los ensayos de la digestibilidad in vitro, el origen del inóculo mostró un efecto significativo en algunas variedades. Debido a las diferencias en los ensayos in vitro, se recomendó el uso de inóculos específicos de las especies para las evaluaciones de alimentos según el animal al que se destina. Asimismo, B. decumbens cv. Basilisk presentó la mejor digestibilidad in vitro (DMSiv y DFDNiv) en inóculo bovino, mientras que B. humidicola cv. Tupi tuvo mejor digestibilidad in vitro (DMSiv y DFDNiv) en inóculo ovino.

Abstract It was hypothesized that it is possible that inoculum from different ruminant species with different digestive abilities feeding from a certain forage may show different feed utilizations comparing to other ruminant species. Five Brachiaria grasses were evaluated: B. decumbens cv. Basilisk, B. decumbens access D70, B. humidicola cv. Tupi, B. humidicola cv. Common, and B. ruziziensis access R124, at two regrowth ages (21 and 42 d). Production, bromatological content, in vitro dry matter digestibility (ivDMD) and in vitro neutral detergent fiber digestibility (ivNDFD) were analyzed using bovine or ovine inoculums. The experiment used a 5 × 2 × 2 factorial design and found significant effects for grass variety and regrowth age. In addition, significant interactions from grass × age on dry matter, crude protein, neutral detergent fiber and acid detergent fiber of total sample and leaf blade were found. There were significant effect of grass variety and grass age on forage mass, leaf blade/stem ratio, leaf blade, stem, senescent material and growth. In vitro digestibility assays of inoculum source showed significant effect in some varieties. Due to differences in in vitro assays, it was recommended the use of species-specific inoculums for feed evaluations according to the animal it is intended for. Also, B. decumbens cv. Basilisk presented the best in vitro digestibility (ivDMD and ivNDFD) in bovine inoculum, whereas B. humidicola cv. Tupi had better in vitro digestibility (ivDMD and ivNDFD) in ovine inoculum.