Frequent and inappropriate use of all classes of antiparasitic drugs in small ruminants has led to failures in their effectiveness, culminating in a global problem of anthelmintic resistance. Brazil stands out as one of the world's leaders in publications about anthelmintic resistance, and for having the most numerous reports of this resistance in small ruminants in the Americas. These studies have involved mainly the fecal egg count reduction test (FECRT) and its correlation with field management practices. In vivo effectiveness testing is conducted in areas where livestock is of greater economic significance, e.g., in the South (sheep) and Northeast (goats), or is important for research and economic centers, such as the Southeast (sheep). The most widely studied species is sheep, for which the widest range of drugs is also evaluated. Despite significant advances achieved in molecular research, laboratory analyses should include knowledge about the reality in the field so that they can become feasible for the producer. Moreover, molecular studies can be underpinned by the analysis of field studies, such as the maintenance of antiparasitic effectiveness over time and the mechanisms involved in this process.Keywords: Small ruminants, anthelmintic resistance, sheep, goat, gastrointestinal nematodes. ResumoO uso frequente e inapropriado de todas as classes de antiparasitários em pequenos ruminantes levou a falhas de eficácia, culminando na problemática global de resistência anti-helmíntica. O Brasil destaca-se como sendo um dos pioneiros nas publicações com resistência anti-helmíntica no mundo e por ter o maior número de relatos em pequenos ruminantes na América. Essas pesquisas envolvem principalmente o teste da redução da contagem de ovos nas fezes (TRCOF) e sua correlação com as práticas de manejo utilizadas no campo. Os estudos de testes de eficácia in vivo localizam-se em áreas onde há maior importância dos rebanhos como nas Regiões Sul (ovinos) e Nordeste (caprinos), ou com importância em polos de pesquisa e econômicos, como a região Sudeste (ovinos). Ovina é a espécie mais estudada e com maior gama de drogas avaliadas. Mesmo com grande avanço em pesquisas moleculares, as análises laboratoriais devem envolver o conhecimento da realidade do campo para que possam se tornar viáveis ao produtor. Além disso, a análise dos estudos de campo pode nortear estudos moleculares como, por exemplo, a manutenção da eficácia das drogas ao longo dos anos e os mecanismos envolvidos em tal processo.

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-This study was designed to investigate the effect of early weaning and concentrate supplementation on performance and metabolic profile of lambs in four production systems on pasture: suckling lambs not supplemented until slaughter; suckling lambs supplemented with concentrate in creep feeding until slaughter; early weaned lambs not supplemented until slaughter; early weaned lambs supplemented with concentrate until slaughter. Performance was assessed by average daily gain (ADG) and body condition score (BCS) measurements. Concentrate supplementation has similar response to suckling on the performance and metabolic profile of animals, and may be considered an efficient strategy to improve the nutritional status of early weaned lambs.

Lambs are the most susceptible category for parasite infections; therefore, the choice of the production system can influence nutritional status and reduce parasite infections. The present study aimed to evaluate the endoparasites and nutritional status of meat lambs in seven production systems. In the feedlot, they were (S1) early weaned lambs in feedlot and (S2) unweaned lambs in feedlot with controlled suckling. On pasture, they were (S3) early weaned lambs on pasture without supplementation, (S4) early weaned lambs on pasture with concentrate supplementation post-weaning, (S5) unweaned and unsupplemented lambs on pasture, (S6) unweaned lambs on pasture with concentrate supplementation and creep-feeding and (S7) unweaned lambs on pasture with free access to creep-grazing on white clover (Trifolium repens). Suffolk lambs (n = 132) were evaluated from 45 to 101 days of age, at 14-day intervals (0, 14, 28, 42 and 56 days). Parasite faecal egg count (FEC), FAMACHA score (FMC), average daily weight-gain and body condition score (BCS) were evaluated. The animals were treated with anthelmintics when they had FMC 3, 4 or 5 and/or FEC above 700. BCS and FEC (r = –0.361) and BCS and FMC variables (r = –0.313) were negatively correlated (P ≤ 0.01). FEC was lower in feedlot and in creep-feeding animals than in the other systems after the second evaluation (28 days). The weaned feedlot-lamb and controlled-suckling systems presented the best performance. On pasture, the animals in creep-feeding and creep-grazing had the best performance. Weaned and unsupplemented lambs on pasture had the lowest daily weight-gain (63 g/day) and the highest FMC scores (43% of animals) and the lowest BCS (mean 1.5). The endoparasite and nutritional statuses of the lambs were strongly correlated and were influenced by the production system, mainly when the ewes were present and the lambs received supplementation on pasture.

The aim here is to present data on the efficacy of anthelmintics in sheep flocks in Rio de Janeiro, Brazil, and to discuss the interpretation of the fecal egg count reduction test (FECRT) for each nematode genus. Fecal eggs counts and pre- and post-treatment coprocultures were performed, the former to evaluate the efficacy of and the latter to determine the overall parasite prevalence. An additional efficacy test was performed at Farm # 1 a year after the initial test. Severe anthelmintic resistance was found for the flocks, with no FECRT sensitivity at any of the 22 farms evaluated. However, an analysis of the infective larvae showed that some drugs were effective against certain parasitic genera; i.e., levamisole was more effective against Haemonchus spp. and moxidectin against Trichostrongylus spp. In the additional FECRT performed at Farm # 1, moxidectin and nitroxynil were ineffective separately, but when applied in combination they were highly effective due to their efficacy against Haemonchus (nitroxynil) and Trichostrongylus (moxidectin), respectively. The use of the FECRT targeting the parasitic nematode species prevalent on farms may make it possible to choose more effective anthelmintics.

RESUMO Desempenho, características de carcaça e custos da terminação de cordeiros Suffolk em sistemas com desmame precoce e amamentação controladaO objetivo deste trabalho foi avaliar o desempenho, as características de carcaça e os custos da terminação de cordeiros Suffolk em três sistemas: (1) cordeiros desmamados com 22 kg de peso corporal (PC) e mantidos em pastagem com suplementação concentrada até o abate; (2) cordeiros desmamados com 22 kg de PC e confinados até o abate; (3) cordeiros mantidos em amamentação controlada após atingirem 22 kg de PC e confinados com alimentação em creep feeding até o abate. Os valores de ganho médio diário (GMD) foram 224 g/dia para os cordeiros desmamados e suplementados em pastagem; 386 g/dia para os cordeiros desmamados e confinados, e 481 g/dia para os cordeiros mantidos em amamentação controlada. O peso de corpo vazio e a deposição de gordura visceral foram maiores em The performance, carcass traits and finishing costs of Suffolk lambs were evaluated in three systems: (1) lambs weaned with 22 kg of body weight (BW) and supplemented with concentrate on pasture until slaughter; (2) lambs weaned with 22 kg BW and fed in feedlot until slaughter; (3) lambs maintained in controlled nursing after 22 kg BW and creep fed in feedlot until slaughter. Average daily gain (ADG) was 224 g/d for lambs weaned and supplemented with concentrate on pasture, 386 g/d for lambs weaned in feedlot and 481 g/d for lambs under controlled nursing. Empty body weight and visceral fat deposition were highest in lambs from feedlot systems. Carcass weights and carcass yields were highest for lambs in controlled nursing. Finishing total costs were highest in controlled nursing and lowest in the system with weaning in feedlot. High concentrate diet associated with controlled nursing in feedlot allowed lambs to reach the growth potential and carcasses with higher weights, higher yields and higher fat content. After weaning, lambs in feedlot fed with high concentrate diet had higher weight gain than lambs supplemented with concentrate on pasture. Carcasses produced under these two systems presented the same characteristics. The system with weaning in feedlot showed the lowest cost per kg carcass.

Ruminants Full-length research article Can the strategies for endoparasite control affect the productivity of lamb production systems on pastures? ABSTRACT-The objective of this study was to evaluate the productivity and carcass traits of unweaned Suffolk lambs finished on pasture and subjected to three strategies for endoparasite control: prophylactic treatment of all animals every 28 days; treatment of animals with a cut off number of nematode fecal egg count (FEC) ≥ 700; and treatment of animals using the FAMACHA scores ≥ 3. Average daily weight gain (ADG) and FEC were evaluated every 14 days for 112 days. Body condition scores and carcass characteristics were assessed before and after slaughter, respectively. Animal productivity was calculated based on animal stocking rate, ADG, and weight variation per area. Animal productivity, pasture, and carcass characteristics did not differ among strategies of parasite control. Parasite control strategies did not affect the productivity of lambs on pasture or carcass characteristics. Thus, the use of selective treatments can be considered advantageous due to decreased selection pressure for resistant parasite populations and lower use of drugs.

Meat composition is an important aspect on INTRODUÇÃOA produção de carne caminha em direção à diversificação e oferta de produtos de melhor qualidade. Isso se deve ao estreitamento do mercado e ao fato de os consumidores estarem mais conscientes em relação à própria saúde, considerando os aspectos sanitários dos produtos e, especialmente, fatores como a presença de elevado teor de gordura neles. Esses são alguns dos fatores que têm estimulado a indústria da carne e os pesquisadores da ciência a procurarem soluções para diminuir o teor de ácidos graxos saturados e aumentar o de ácidos graxos poliinsaturados.