Banca de DEFESA: FRANCISCA FERNANDA DA SILVA ROBERTO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : FRANCISCA FERNANDA DA SILVA ROBERTO
DATA : 22/02/2018
HORA: 09:00
LOCAL: Sala POP, Centro de Convivência do Campus Central - UFRN.
TÍTULO:

Evaluation of naturally infected sheep by gastrointestinal nematodes under intermittent grazing on cultivars of Brachiaria brizantha

PALAVRAS-CHAVES:

coproculture, FAMACHA^©, Haemonchus sp., sheep, tropical pasture, Trichostrongylus sp.

PÁGINAS: 76
GRANDE ÁREA: Ciências Agrárias
ÁREA: Zootecnia
SUBÁREA: Produção Animal
RESUMO:

The objective of this study was to evaluate the response of naturally infected sheep by gastrointestinal nematodes under intermittent grazing conditions in different Brachiaria brizantha cultivars. The experiment was carried out in the Experimental Area of the Group of Forage Research, located at the Macaíba Campus of the Federal Universidade of Rio Grande do Norte. The experimental period was from 03/31/17 to 08/31/2017, which corresponded to two cycles of grazing. The animals were kept in a semi-intensive system with intermittent grazing and supplemented. We used 48 sheep, with no defined racial pattern, with a mean initial weight of 19.04 kg ± 0.96, randomly distributed in four pickets composed of Marandu, Xaraés, Piatã and Paiaguás. The experimental design was a randomized block design with 12 replicates in the animals and two blocks of the cultivars. The phenotypic variables evaluated weekly were egg counts per gram of faeces (EPG), coproculture, globular volume (VG), FAMACHA^©, weighing and body condition score (BCS). The recovery of infective larvae in the pasture and in the soil, were according to the exchange of the animals in the pre and post grazing pickets. The B. brizantha cultivars evaluated influenced the parasitic load of the animals, which were mixed and massive with values above 600 eggs/g independent of the grazed cultivar, with a significant difference in these values among the cultivars, varying from 635.71 (Xaraés) to 1422.2 (Marandu). Among the grazing cycles, there were differences in the EPG of the animals kept in the Marandu cultivar (999.1 and 1422.2), being greater in relation to the others. In the coproculture were found the following genera: Haemonchus sp., Trichostrongylus sp., Strongyloides sp., and Oesophagostomum sp. The Haemonchus sp. was the most prevalent genus (over 80%) in all cultivars and grazing cycles. In the first grazing cycle, there was difference in VG of the animals kept in the Piatã (25.96%) and Xaraés (22.51%) cultivars, and those maintained in the other cultivars showed intermediate values. As for FAMACHA, the animals remained more frequently in grades 1, 2 and 3, in order of importance in cycle 1, but in cycle 2, the concentration with more than 50% of the individuals was in grade 1. Regarding the weight of the animals , the group maintained in the Xaraés cultivar differed from the others (P <0.05), with lower mean values in both cycles (21.79 and 26.91 kg). The BCS of the animals was concentrated at 3 in the first grazing cycle and at 3, 3.5 and 4 in the second cycle. The cultivars Marandu and Paiaguás presented the highest averages of larvae in the pasture. The concentration of larvae was found in pre-grazing and in the lower portion. The first cycle of grazing obtained a higher count of larvae. It was possible to recover larvae of free and infecting life stages of the genera Haemonchus sp., Trichostrongylus sp. and Strongyloides sp. In soil samples from all cultivars, it was possible to recover larvae from the free-living and infecting stages of the genera Haemonchus sp. and Trichostrongylus sp. The cv. Marandu presented higher mean free-stage larvae (5.37) and Haemonchus sp. (0.53). In the first grazing cycle there was a higher count of nematodes in the soil samples when compared to the second, except for cv. Marandu. It can be concluded that B. Brizantha cultivars promote climatic conditions for the development and survival of the distinct life phases of the different gastrointestinal nematodes according to the morphological characteristics, influencing the parasitic load of the animals. However, all cultivars are recommended for grazing, since cultivars Piatã and Xaraés promote lower parasitic loads in the environment and in animals. And the cultivars Marandu and Paiaguás, even resulting in higher parasitic loads, gave better nutritional conditions to the animals without compromising the phenotypic variables.

MEMBROS DA BANCA:
Presidente - 986835 - GELSON DOS SANTOS DIFANTE
Interno - 1714262 - LILIAN GIOTTO ZAROS DE MEDEIROS
Externo ao Programa - 6349507 - MARIA DE FATIMA DE SOUZA
Externo à Instituição - LUIZ DA SILVA VIEIRA - EMBRAPA