Fernando Paim Costa

Desempenho de novilhos F1s Angus-Nelore em pastagens de Brachiaria decumbens submetidos a diferentes regimes alimentares

O objetivo deste experimento foi avaliar as eficiencias biologica e economica de sistemas de alimentacao, durante os periodos criticos, como alternativa de reducao da idade de abate de bovinos recriados em pastagens de Brachiaria decumbens. Sessenta bezerros F1s Angus-Nelore desmamados foram distribuidos nos seguintes tratamentos: A) sem suplementacao; B) suplementacao somente no primeiro periodo seco; C) suplementacao apenas na segunda seca; D) suplementacao nos dois periodos secos; e E) suplementacao no primeiro periodo seco e confinamento no segundo. Os suplementos utilizados foram racoes comerciais fornecidas diariamente em quantidades equivalentes a 0,8 e 0,9% do peso vivo, nas primeira e segunda secas, respectivamente. O confinamento durou 100 dias e os novilhos receberam, ad libitum, uma racao contendo 40% de feno de Brachiaria decumbens e 60% de concentrado. O periodo experimental foi da desmama ate o abate (460 kg). Durante o primeiro periodo seco, os animais suplementados apresentaram maiores ganhos de peso diario (GPD) que os nao suplementados, 460 e 70 g, respectivamente. Durante o segundo periodo seco, os animais confinados apresentaram maiores GPD (1.285 g), seguidos dos suplementados em pasto (580 g), enquanto os nao suplementados perderam peso (-180 g). Houve aumento na capacidade de suporte dos pastos, onde os animais receberam suplementacao, em 24 e 30%, durante os primeiro e segundo periodos secos, respectivamente. Os animais que passaram por restricao alimentar no segundo periodo seco apresentaram ganho compensatorio, quando cessou a restricao, mas esse nao foi suficiente para que os animais atingissem pesos de abate a mesma idade dos suplementados. As idades de abate foram 30,1; 28,0; 26,6; 24,2; e 22,0 meses, respectivamente, para os tratamentos A, B, C, D e E. Tambem foi apresentada a avaliacao economica.

Desenvolvimento e desempenho reprodutivo de novilhas Nelore criadas a pasto nos cerrados do Centro-Oeste brasileiro

A model fitted to grazing females Nellore during the rearing periods of the Cerrado Region of Central Brazil was simulated and validated in this study. Body weight gain (BWG) was determined during three years as follows: 1) first dry season after weaning on Brachiaria brizantha (Hochst) Stapf., 2) rainfall season and 3) second dry season both on Panicum maximum Jacq. cv. Tanzânia and averaged 0.020, 0.550, and 0.172 kg, respectively. In the second rainfall season during the rearing period heifers grazed Brachiaria decumbens Stapf. At 24.33 months of age the heifers body weight (BW) averaged 299 kg while in the beginning of the mating season their age and BW averaged, respectively, 25.51 ± 0.99 months (CV = 3.50%) and 309.33 ± 19.19 kg (CV = 6.20%). On average, animals calved 326.71 ± 19.98 days (CV = 6.11) after the beginning of the mating season and 36.26 months of age. The mean pregnancy rate was 88.4%. The pregnant heifers were 25.58 ± 9.97 days older and 9.8 ± 7.04 kg heavier than those non-pregnant. The mean BW and body condition in the middle of the mating season were 360 ± 31.00 and 2.94 ± 0.60, before calving 436 ± 30.86 kg and 4.57 ± 0.40, and at weaning 369 ± 33.89 kg and 3.11 ± 0.64, respectively. The mean weaning rate was of 75.6%. Calves mean BW and age at weaning were of 158 ± 20.1 kg and 202 ± 16.6 days, respectively. Nellore heifers grazing Brachiaria decumbens Stapf. and bred at 24/26 months of age showed high production.

Trypanosomatid prevalence in Nezara viridula (L.), Euschistus heros (Fabricius) and Piezodorus guildinii (Westwood) (Heteroptera: Pentatomidae) populations in Northern Paraná, Brazil

The stink bug complex in soybeans has a great potential to cause damage, their control has been difficult due to high population densities at the end of the season. Studies related to entomopathogenic organisms in stink bugs are interesting for their possibilities to be used as biological control agents and because they could be an etiological agent in mass rearing. We determined the prevalence of trypanosomatids in the most important species of the stink bug complex in soybean, from Brazil, Nezara viridula (L.), Euschistus heros (Fabricius) and Piezodorus guildinii (Westwood). Insects were collected in soybean and on alternate hosts during the intercrop season. Hemolymph drops from each adult were mounted on slides and observed under microscope; stink bug numbers with and without flagellates were recorded. The flagellates found in P. guildinii or E. heros populations were smaller than that found in N. viridula. The higher prevalence of the trypanosomatids was observed on soybean reaching a peak of 30% of the sampled N. viridula specimens in January, 2001, and 44% prevalence in February, 2003. The maximum prevalences (16%) in P. guildinii were observed in January and February, 2003 and on July 27, 2003 with 20% of the specimens infected. Flagellates in the hemolymph of E. heros were less frequent (maximum prevalence of 8.7%), suggesting that this species is less susceptible than N. viridula and P. guildinii. Trypanosomatid prevalence was higher than that observed for entomopathogenic fungi, however they seem to be inefficient control agents in short term condition.