Reproductive performance of European-breed ewes in different seasons of the year under mid-latitude.

The study evaluated the reproductive performance of Ile de France, Texel, Suffolk and crossbred ewes in different seasons, considering season of mating, age, body condition score and breed. The herd was located at geographic coordinates -25.66114429 S, -49.27262198 W, in Fazenda Rio Grande, Paraná State, southern Brazil, in a semi-intensive system. 643 mating were evaluated, under natural oestrous conditions in 10 consecutive breeding seasons (2015-2019), under a body condition score between 2.5 and 3.5 in 93.9%. Data were analysed using Chi-square tests, binary logistic regression, ANOVA and t-test. Considering the breeds and crossbred animals, a pregnancy rate (PR) of 83% (winter), 91% (autumn) and 89% (summer) with no differences between them was obtained, except for 77% PR in spring (p < .05). Ile de France and crossbred ewes showed similar PR in all four seasons. Suffolk ewes showed similar fertility rates in summer, autumn and winter, but reduced in spring (p < .05); Texel ewes showed lower PR in summer and spring compared to autumn and winter (p < .05). The twin PR (TPR) in autumn, winter and spring showed no differences, except for summer (p < .05). Age did not influence the PR of ewes <2 years, 2-8 years and >8 years in the seasons, except in summer. It was concluded that the reproduction of European ewes breeds under medium latitude, combined with the use of constant management and feeding conditions, resulted in a fertility rate above 77% in all seasons, resulting in constant production of lambs.

Resistance of gastrointestinal nematodes to anthelmintics in sheep (Ovis aries)

O teste de redução da contagem de ovos de helmintos por grama de fezes (FECRT) foi usado para testar a eficiência dos antihelmínticos em 42 propriedades produtoras de ovinos, em cinco diferentes regiões no Estado do Paraná, Brasil. O estudo foi realizado entre Julho 1996 a Julho de 2000. Foram avaliados animais com infecção natural. Cinco drogas foram usadas só ou em combinação (benzimidazole, imidazothiazole, ivermectin, milbemicina e closantel). Resultados mostraram que a prevalência de resistência foi alta para todos os antihelmínticos avaliados: 88.1% para benzimidazoles (oxfendazole), 78.6% para ivermectin, 56.4% para closantel, 38.7% para closantel + oxfendazole, 38% para levamisole, e 23.6% para moxidectin. Havia resistência múltipla em todas fazendas estudadas. Na identificação das larvas de helmintos recuperadas das culturas de fezes após o tratamento verificou-se que maioria pertenciam a Haemonchus sp. e Trichostrongylus sp. O fracasso das drogas existentes no mercado em combater a verminose é considerado um assunto importante. No presente artigo algumas sugestões são discutidas para melhorar a situação, elas incluem uma mudança de atitude em relação ao uso indiscriminado de antihelmínticos.