Moxidectin residues in tissues of lambs submitted to three endoparasite control programs.

The indiscriminate and continuous use of anthelmintic drugs has promoted the selection of resistant parasites population, the presence of drug residues in food products, and heavy environmental contamination. The aim of the present study was to determine the presence of antiparasitic drug residues in 42-days old lamb serum and tissues, submitted to three endoparasite control programs: preventive treatment (PT) using moxidectin (MOX) at every 28days; selective treatment (FEC) using MOX when fecal egg count was greater than or equal to 700; and selective treatment (FMC), using MOX when FAMACHA/FMC score was 3 and above. For this purpose, MOX residues were quantified in serum, muscle, fat, liver and kidney. Lambs were slaughtered when reaching 30kg of body weight, and after a 28-day MOX withdrawal period. Before slaughter, blood was collected to determine the concentration of MOX in serum. Tissues and organ samples were collected at slaughter. The quantitation of MOX residues was performed using liquid chromatography tandem mass spectrometry (LC-MS/MS). From the 756 tissue samples analyzed, only one sample of fat from the PT group showed residue levels (586.3µg/kg) above the maximum residue limit (MRL) of 500µg/kg. No treated lambs presented traces of MOX residues in fat and liver, suggesting possible environmental contamination. In conclusion, all weaned lambs, produced in continuous grazing and subjected to gastrointestinal parasite control programs via selective (FEC and FMC) or preventive (PT) treatment, displayed a low risk (<1%) of MOX residues above the MRL in muscle, fat, kidney, and liver.

Gene silencing of Dim-1, a member of the disorganized muscle family, in Haemonchus contortus.

RNA interference has been widely used in parasites. In Haemonchus contortus, reproducible silencing has been reported; however, in this species an altered phenotype has been observed for only a few genes silenced by RNA interference. The aim of this work was to evaluate the effect of silencing Dim-1, a member of the disorganized muscle family on third stage larvae (L3) of H. contortus. Effective silencing of Dim-1 in L3 led to reduced L3 migration and slowed larval development from L3 to early L4. To our knowledge, this is the first report to demonstrate Dim-1 silencing affecting phenotypic characteristics of this parasite.

Duddingtonia flagrans in the control of gastrointestinal nematodes of horses.

Horses can harbor a large amount of parasites that may cause serious clinical signs even death. The aim of this study was to evaluate the predatory activity of the fungus Duddingtonia flagrans against infective larvae (L3) of gastrointestinal nematodes of horses in fecal culture. The experimental design was completely randomized with three treated groups (G1, G2 and G3) and one control (CG), using eight animals/group. The treated animals received G1: 1.5 × 10(5); G2: 3 × 10(5) and G3: 6 × 10(5) chlamydospores of D. flagrans/kg body weight during 21 days. The fungi preparation was given at every other three-day interval. Faecal samples were collected during 30 days, on the same interval, to perform the fecal egg counts (EPG) and fecal culture for each horse. All groups demonstrated similar results for the EPG (P > 0.05) counts. D. flagrans significantly reduced (P < 0.05) the number of infective larvae after 72 h-interval between treatments. The G2 and G3 promoted higher results (P < 0.05) of L3 reduction compared to the CG. The biological control with the predacious fungi D. flagrans is still a promising free-living parasite regulator alternative to be use in livestock.

Carcaças e componentes não-carcaça de cordeiros terminados em pasto de azevém recebendo suplementação concentrada / Carcasses and non carcasses components of lambs on Italian ryegrass receiving concentrate supplementation

O trabalho foi desenvolvido com o objetivo de avaliar a resposta das características objetivas e subjetivas das carcaças e dos não componentes da carcaça de cordeiros desmamados precocemente e terminados em pasto de azevém anual ao fornecimento crescente de suplemento concentrado (sem suplementação; 0,9%; 1,8% do peso corporal e ad libitum) na dieta. Os cordeiros foram abatidos ao atingirem 32kg de peso corporal e medidas corporais foram tomadas antes do abate. Após o abate, registraram-se os pesos da carcaça quente, do conteúdo digestivo e dos não-componentes da carcaça. As carcaças permaneceram por 24 horas em câmara fria a 5°C, obtendo-se o peso da carcaça fria. Obtiveram-se os rendimentos e as medidas objetivas e subjetivas das carcaças e, por cálculos, as compacidades de perna e carcaça. Os dados foram submetidos às análises de regressão e de correlação simples. A suplementação concentrada apresentou efeito linear positivo (P<0,05) sobre pesos e rendimentos de carcaça quente e fria, compacidade de perna e de carcaça, estado de engorduramento e conformação das carcaças. A oferta crescente de suplementação concentrada aos cordeiros jovens desmamados e terminados em pasto de azevém promoveu a obtenção de carcaças maiores e com rendimento superior, com melhor conformação e estado de engorduramento, podendo resultar em melhores oportunidades de comercialização e de preços pagos ao produtor.

The study was performed to evaluate the subjective and objective measurements of the carcasses and non-carcasses components of weaned lambs grazing on Italian ryegrass pasture fed with different levels of concentrate supplementation (without supplementation, 0,9%, 1,8% of body weight and ad libitum). Lambs were slaughtered at 32kg of live weight. After slaughtering, hot carcass, digestive content and weight of non-carcass components were recorded. Weight of cold carcasses was assessed after the refrigeration for 24h at 5°C. Weight, yield and carcasses measurements were taken and then the leg and carcass compactness were calculated. Data were subjected to regression and simple correlation analysis. The concentrate supplementation levels had a positive linear effect on the weights and yields of hot and cold carcass and leg and carcasses compactness. Supplementation of weaned lambs grazing on annual ryegrass enabled to get carcasses of better conformation and fat covering. These effects may result in better price opportunities and marketing for farmers.

Composição tecidual e perfil de ácidos graxos do lombo de cordeiros terminados em pasto com níveis de suplementação concentrada / Tissue composition and fatty acids profile of lambs loin finishing on pasture with concentrate supplementation

A composição tecidual da carne é característica importante na avaliação da qualidade sensorial e nutricional do produto. O presente trabalho avaliou a composição tecidual e o perfil de ácidos graxos do lombo de cordeiros desmamados aos 42 dias de idade média e terminados em pasto de azevém com níveis diários de suplementação concentrada (0, 1 e 2 por cento do PV e ad libitum). O delineamento experimental foi de blocos ao acaso com três repetições. Os cordeiros foram abatidos ao atingirem 32kg de peso vivo. O lombo direito foi utilizado para determinação da composição tecidual e o esquerdo para análise de perfil de ácidos graxos. As análises de variância e de regressão foram realizadas com auxílio do programa SAS (2001). A suplementação concentrada de cordeiros terminados em pasto não teve efeito (P>0,05) sobre o desenvolvimento muscular e ósseo; no entanto, promoveu acréscimo linear na deposição de gordura intermuscular e total. Os níveis de suplementação estudados não tiveram efeito (P>0,05) sobre a quantidade e o percentual de cada ácido graxo da carne dos cordeiros. A suplementação concentrada de cordeiros desmamados em pasto de azevém aumentou a deposição de gordura na carcaça sem afetar a qualidade da carne para o consumo humano, considerando-se o perfil de ácidos graxos.

Meat composition is an important aspect on evaluation of sensory and nutritional quality of the product. This work had the objective of evaluating tissue composition and fatty acids profile of loin lambs weaned at 42 days of mean age and finished on ryegrass pasture with levels (0 percent; 1 percent and 2 percent of BW; ad libitum) of daily concentrate supplementation. The experiment was allocated in randomized blocks design with three replications. Lambs were slaughtered when individual live weight reached 32kg. Tissue composition was determined in right loin and left loin was used for fatty acids profile analyses. Analysis of variance and regression were performed by using SAS (2001). The concentrate supplementation of lambs finished on pasture did not affect (P>0.05) muscle and bone development, however, promoted linear increase on intermuscular and total fat. Levels of supplementation did not affect (P>0.05) the amount and percentage of each fatty acids in lambs meat. The concentrate supplementation of weaned lambs finished on ryegrass pastures increased fat covering on carcass without changing meat quality to human feeding considering fatty acids profile.