Desempenho nutricional de bovinos em pastejo durante o período de transição seca-águas recebendo suplementação proteica

This experiment aimed to evaluate the effects of different amounts of a protein supplement on intake, digestibility, and metabolic characteristics of nitrogen utilization in cattle during the dry-to-rainy transition period. Five Nellore bulls fitted with rumen cannulae, averaging 273 kg of body weight (BW), were used. The animals grazed five signal grass paddocks (0.34 ha). The experiment was carried out according to a 5 × 5. Latin square design. The treatments consisted of five different amounts of offered supplement: 0, 1.25, 2.5, 5.0, and 10.0 g/kg BW. The supplement was composed by soybean meal, corn grain, urea and ammonium sulphate in order to present 340 g of crude protein (CP) per kg as fed. The or- ganic matter (OM), CP, and digested OM intakes increased linearly (p<0.01) as the amount of supplement increased. Despite this, there was no effect of supplement amounts (p>0.10) on pasture intake. The total and ruminal digestibility of OM and CP were linearly increased (p<0.01) as supplement amount increased. The increase in the supplement amount increased linearly (p<0.01) the nitrogen balance in the rumen and animal body, and the production of microbial nitrogen in the rumen. Protein supplementation for grazing cattle during dry-to-rainy transition season does not affect pasture intake. Despite this, the supplementation increases the nitrogen balance and the efficiency of nitrogen utilization. This seems to be caused by an improvement on the nitrogen status in the animal metabolism.Objetivou-se avaliar os efeitos do fornecimento de quantidades crescentes de suplemento proteico durante o período de transição seca-águas sobre o consumo, a digestibilidade e sobre aspectos do metabolismo de compostos nitrogenados em bovinos. Foram utilizados cinco novilhos Nelore com peso corporal (PC) inicial de 273 kg, fistulados no rúmen e mantidos individualmente em piquetes de capim-braquiária com 0,34 ha. O experimento foi estruturado em delineamento em quadrado latino 5 × 5. Os tratamentos foram definidos de maneira a suplementar os animais em 0; 1,25; 2,5; 5,0 e 10,0 g de suplemento por kg de PC. O suplemento foi composto por farelo de soja, milho, ureia e sulfato de amônio de forma a apresentar 340 g de proteína bruta (PB)/kg de matéria natural. Verificou-se que os consumos de matéria orgânica (MO), PB e MO digerida foram incrementados linearmente (p<0,01) com o aumento no fornecimento de suplemento. Contudo, nenhum efeito foi veri- ficado (p>0,10) sobre o consumo de pasto. A digestibilidade total e ruminal da MO e PB foi incrementada linearmente (p<0,10) à medida que se ampliou a quantidade de suple- mento fornecida. O aumento na quantidade de suplemento ampliou linearmente (p<0,01) o balanço de compostos nitrogenados no organismo do animal e no ambiente ruminal e a produção de compostos nitrogenados microbianos no rúmen. A suplementação proteica para bovinos manejados em pastagens durante o período de transição seca-águas não afeta o consumo voluntário de pasto. Observa-se, contudo, ampliação no balanço de compostos nitrogenados e na eficiência de uso do nitrogênio como reflexo de melhorias do status de nitrogênio no organismo animal

Levels of supplementation for grazing pregnant beef cows during the dry season

The objective of this study was to evaluate the effect of different levels of multiple supplement supply on the nutritional characteristics and productive performance of pregnant cows grazing on Brachiaria decumbens Stapf. during the dry season. The experimental area was composed of four 3.0 ha paddocks with availability of potentially digestible dry matter of 2,582 kg/ha. Twenty-eight crossbred pregnant cows with predominance of Zebu breed at body weight of 446±12 kg were utilized in a completely randomized experimental design. Treatments consisted of mineral supplement (control treatment) and supply of multiple supplement at 0.5, 1.0 and 1.5 kg/animal/day with 300 g crude protein (CP)/kg of dry matter (DM). There was quadratic effect of multiple supplementation levels on daily weight gain and a linear increase for final body condition score. The intakes of DM, organic matter (OM) and total digestible nutrients presented no effect with levels of multiple supplement. The coefficients of apparent digestibility of DM and OM had cubic effect with multiple supplementation levels. There was no effect of levels of multiple supplementation on the microbial nitrogen flow and efficiency, but the microbial nitrogen flow in relation to nitrogen intake showed decreasing linear profile. The supply of 1.0 kg of multiple supplement optimizes the performance of grazing cows during the dry season

The relictual population of the purple clam Amiantis Purpurata (l.) in northern Patagonia (Argentina): the history of a warm-temperate-water neogene survivor

The purple clam Amiantis purpurata (Lamarck) is a warm-temperate species inhabiting shallow water along the coast from Espiritu Santo (Brazil) to northern Patagonia. It is one of the few survivors of the middle–late Miocene faunal turnover which was characterized by the appearance of new taxa, most of them living now along the Argentinean coast. In order to study the biogeographic history of A. purpurata, a detailed review of its records was carried out. The oldest record of this species is from late Miocene rocks in Uruguay, and it appears that A. purpurata survived because its wide thermal tolerance range allowed larvae to migrate southwards from Uruguay, settling on the southern coast of Buenos Aires Province and San Matías Gulf. The characteristics of this gulf would have favored the development and settlement of the larvae, thus giving rise to the most abundant southern population during the Pleistocene. At the end of the Pleistocene, A. purpurata also survived the Last Glacial Maximum. During the Holocene, the population of A. purpurata in San Matías Gulf became isolated, but also represented the most abundant southern population of this species. During its brief Neogene history, Amiantis purpurata followed main global, regional and local events; thus it can be considered as an environmental indicator for this period.La almeja púrpura Amiantis purpurata (Lamarck) es una especie de aguas templado-cálidas que habita en aguas poco profundas desde Espíritu Santo (Brasil) hasta el norte de Patagonia. Es uno de los pocos sobrevivientes del intercambio faunístico del Mioceno medio–tardío, que se caracterizó por la aparición de nuevos taxa, la mayoría de ellos vivientes en la actualidad a lo largo de la costa argentina. Con el fin de reconstruir su historia biogeográfica, se llevó a cabo una revisión detallada de los registros. El registro más antiguo de A. purpurata proviene del Mioceno tardío en Uruguay, y sobrevivió debido a su amplia tolerancia térmica lo que habría permitido que las larvas migren desde Uruguay hacia el sur, donde se establecieron en la costa sur de la Provincia de Buenos Aires y en el Golfo San Matías. Además, las características de este golfo han impulsado el desarrollo y asentamiento de las larvas, lo que daría lugar a la población más abundante situada más al sur durante el Pleistoceno. Al final del Pleistoceno, A. purpurata también sobrevivió al Último Máximo Glacial y, una vez en el Holoceno, la población de A. purpurata del Golfo San Matías quedó aislada, lo que representa la población más abundante y austral de esta especie. A lo largo de su breve historia geológica durante el Neógeno, Amiantis purpurata acompañó a los principales acontecimientos ocurridos a escala global, regional y local; por lo tanto, esta especie puede ser considerada como un indicador ambiental para este período.Fil: Bayer, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Gordillo, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones En Ciencias de la Tierra; ArgentinaFil: Morsán, Enrique . Instituto de Biología Marina y Pesquera Almirante Storni; Argentin