Identificação citogenética de quatro gerações de búfalos mestiços mantidos em um programa de conservação na ilha de Marajó/Brazil

The domestic buffaloes were divided in two groups: the river buffalo, which has chromosome number 2n=50 and the swamp buffalo, 2n=48. The crosses between these animals result in F1 specimens with 2n=49 which are viable and fertile. In Brazil the Baio type and the Carabao breed buffalo are found in small number and maintained in genetic conservation programs that aim to keep these groups separated, this way conserving their genetic heritage in situ as well as ex situ. The objective of this study was to evaluate cytogenetically buffaloes from Carabao breed, Baio type and its F1, F2, F3 and F4 crossbreeds kept in a genetic conservation program. The metaphases were obtained from blood culture of 50 animals Carabao breed, 45 Baio type and 10 animals belonging to the crossbreed progeny. The Baio type presented 2n=50 and the Carabao breed 2n=48. In the progeny were observed specimens with chromosome number 2n=48 or 2n=49 with morphological variations in the first pair of chromosomes. The diploid number 2n=49 confirms crossbreeding of the animals from the conservation program. Thus, the exclusion of these animals from the original herds is highly recommended in order to keep separate genotypes for each genetic group.Os búfalos domésticos são divididos em dois grupos: os búfalos de rio, com número diploide 2n= 50 e os búfalos de pântano, 2n= 48. O cruzamento F1 entre estes resultam em animais com 2n= 49, que são viáveis e férteis. No Brasil os búfalos do tipo Baio e da raça Carabao são mantidos em um programa de conservação genética que visa manter esses grupos separados, conservando seu patrimônio genético in situ e ex situ. O objetivo deste estudo foi avaliar citogeneticamente búfalos da raça Carabao, tipo Baio e suas crusas F1, F2, F3 e F4 mantidos em um programa de conservação genética. As metáfases foram obtidas a partir de cultura de linfócitos de 50 animais da raça Carabao, 45 do tipo Baio e 10 descendentes de uma fêmea mestiça. Os animais do tipo Baio apresentaram 2n= 50, os da raça Carabao 2n= 48. Para os descendentes foram observados 2n= 48 e 2n= 49, com variações morfológicas no primeiro par. O número diplóides 2n= 49 confirma a presença de animais cruzados no programa de conservação. Assim, a exclusão destes animais e seus descendentes é altamente recomendada dos rebanhos originais a fim de manter os genótipos separados para cada grupo genético

Reforestation feasibility in area formerly used for cattle rasing in the state of Rondônia, Northwest Brazilian Amazon

Little knowledge on initial behavior of native tree species in recovering landscapes in the Amazon is a current concern for expanding reforestation in the region. Thus, the aim of this study was to evaluate the establishment of native tree species that could be used for reforestation in area previously covered by a pasture of brachiaria grass (Brachiaria brizantha) destined for intensive cattle rasing in the State of Rondônia. For this, there were performed previous diagnostic of landscape changes and the election of tree species based on the ecological group information. Some of the critical macronutrients for plant growth were supplied in the holes to alleviate nutrient deficiencies. In addition, growth and survival parameters were taken to evaluate the initial behavior of species. Six native tree species planted with different combinations (10mx10m, 5mx5m and 3mx3m) had survival rate and growth (total height, girth stem and crown projection area) measured in different intervals: 6-month, 12-month and 24-month after planting. All the species presented survival rate over 90% at 24 months and comparable growth indices to other native species under similar situation and in the region. Overall, Schizolobium amazonicum (bandarra), the non-identified legume tree 1 (acácia grande) and Colubrina glandulosa (sóbrasil) averaged over 90% the highest girth stem growth all over the area. S. amazonicum and the non-identified legume tree 1 (acácia grande) presented the best results for height and canopy area growth parameters, respectively. The combination among native tree species from initial successional ecological groups and fertilizer was favorable to promote reforestation in the conditions of the study area in Rondônia