Maria Angela Machado Fernandes

Produção de ovinos de corte em quatro sistemas de produção

The potential performance of lambs and ewes from the Suffolk breed in pasture of Tifton grass 85 (Cynodon spp.) and ryegrass (Lolium multiflorum) was evaluated in different production systems: lambs weaned with 60 days and kept in pasture; lambs with ewes and kept in pasture; lambs with ewes and kept in pasture with creep feeding; feedlot confined lambs with alfalfa hay + balanced ration. The treatments were applied when the lambs reached 60 days of age until slaughter time, at 32 kg, and were allocated in a completely randomized experimental design, with three replications. A continuous grazing system, with variable stocking rate, was used in pasture treatments. Important effect of the treatments on performance of the lambs was observed. Feedlot confined lambs showed higher daily weight and at lower age at slaughter time. Creep feeding supplementation at 1% LW, did not have effect in lambs with more than 60 days of age kept with the ewes in Tifton 85 grass pasture. The presence of the ewe in the pasture showed important and positive effect in the individual performance of lambs as compared to lambs weaned at 60 days of age.

Rentabilidade da produção de ovinos de corte em pastagem e em confinamento

Os objetivos neste trabalho foram analisar a viabilidade economica de sistemas de producao de cordeiros e identificar os componentes de maior influencia no custo de producao. O estudo foi realizado em duas etapas. Na etapa 1, realizou-se a comparacao de quatro sistemas de terminacao de cordeiros: 1) desmame aos 60 dias e terminacao em pasto; 2) cordeiro com mae em pasto; 3) cordeiro com mae em pasto e concentrado (1% PC/dia) em creep feeding; e 4) desmame aos 60 dias e confinamento. Na etapa 2, um modulo de 150 ovelhas em 9 ha de pasto cultivado nos sistemas em pastagem e 7 ha no confinamento foi proposto a partir do experimento para avaliacoes economicas, considerando a venda de cordeiro vivo terminado ou abate e venda de carne, alem da venda de matrizes. Foram realizados calculos de custo fixo (depreciacao), variavel (materiais, mao-de-obra, transporte, abate, juros, conservacao, despesas gerais) e total (fixo+variavel), lucratividade e rentabilidade, valor presente liquido, taxa interna de retorno e custo/beneficio. O maior custo total foi observado no confinamento e o menor, no sistema de cordeiro terminado com a mae em pasto. A margem liquida na venda de cordeiros foi negativa em todos os sistemas. A venda de carne apresentou margem liquida negativa apenas para terminacao em confinamento. A taxa interna de retorno para venda de carne foi: 1,4% no desmamado em pasto; 4,3% no de cordeiro com mae em pasto; 2,1% no creep feeding; e -2,3% no confinamento. Os componentes do custo operacional total com maior influencia sobre o custo de producao nos sistemas a pasto, em ordem decrescente, foram mao-de-obra e alimentacao; no confinamento, foram alimentacao e mao-de-obra. A venda da carne apresentou lucratividade maior que a venda de cordeiro vivo, com maior valor no sistema sem desmame terminado na pastagem.

Composição tecidual da carcaça e perfil de ácidos graxos da carne de cordeiros terminados a pasto ou em confinamento

The objective of this study was to evaluate tissue composition of loin and leg and fatty acids profile of the meat of lambs in four finishing systems: (1) lambs weaned around 40 days of age and kept in ryegrass pastures until slaughter; (2) lambs kept with their dams in the same pasture until slaughter; (3) same treatment of (2), but daily supplemented with 1% of the body weight in creep feeding; (4) lambs weaned at 40 days of age and confined, fed corn silage and concentrate ad libitum. It was used a complete random experimental design with four finishing systems and three replications. Lambs were slaughtered at body weight of 32 kg. Loins and right legs were used for determining tissue composition and the left loins were used for analyzing fatty acid profile. Length and maximal deep of the muscle, minimal and maximal thickness of backfat and loin eye area were measured on the left legs. Pasture finished weaned lambs showed lower fat deposition on the carcass and leg muscularity index. Muscle development and fat deposition on finished weaned lamb with or without supplementation were similar to the ones observed on feedlot finished weaned lambs. Lambs in creep feeding showed more fatty acids in the meat than pasture weaned lambs. Finishing systems influence tissue composition but they do not affect fatty acid profile in meat for human consumption.

Carcaças e componentes não-carcaça de cordeiros terminados em pasto de azevém recebendo suplementação concentrada

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.

Determination of Moxidectin in Serum by Liquid Chromatography-Tandem Mass Spectrometry and Its Application in Pharmacokinetic Study in Lambs

The widespread use of moxidectin (MOX), a parasiticide used in the sheep breeding, has induced the parasite resistance in Brazilian farms. As a consequence, the farmers often increase the dose and frequency of drug utilization, and disregards safety of meat or milk. In order to establish adequate therapeutic treatment it is necessary to know the pharmacokinetics of the drug in the animals body. Thus, high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed for the determination of MOX in serum lamb. Serum samples were treated with acetonitrile to precipitate proteins. A clean up by dispersive extraction in solid phase (SPE-d), using primary/secondary amine (PSA) and C18 sorbents, followed by freezing was performed. Method validation presented precision (coefficient of variation) and accuracy (recovery%) between 1.7-6.7 and 80.0-107.3%, respectively. The limit of quantification (LOQ) of the method was 2.0 ng mL-1 and a linear response was obtained over a range of 2.0 to 100 ng mL-1. This method was successfully applied to the determination of MOX in serum from suffolk lamb to evaluate the pharmacokinetic profile.

Método FAMACHA para detectar anemia clínica causada por Haemonchus contortus em cordeiros lactentes e ovelhas em lactação

The control of gastrointestinal parasites in small ruminants has traditionally involved the indiscriminate use of anthelmintic drugs that resulted in a high parasite selection pressure for anthelmintic resistance. Selective methods (ex.: FAMACHA/FMC and faecal egg count/EPG), which have good sensitivity to identify animals that need drug treatment, are important alternative methods for parasite control. The objective of this study was to determine the sensitivity and specificity of the FMC method to detect clinical anemia caused by Haemonchus contortus in two highly susceptible categories of Suffolk sheep; suckling lambs and lactating ewes. The ocular conjunctivae of 42 suckling lambs and 35 lactating ewes were evaluated using the FMC method at 14 days interval for five months. Hematocrit (Ht) served as the gold standard for anemia evaluation. To calculate the sensitivity and specificity of the FMC method, different criteria were adopted: animals classified as 4 and 5, or 3, 4 and 5, were considered to be anemic (positive test), and animals classified as 1, 2 and 3, or 1 and 2 were considered to be non-anemic (negative test). Three standard values of Ht (≤22%, ≤19% or ≤15%) were used to confirm anemia. Among the prevalent genera of helminths H. contortus (61.5%) and Ostertagia sp. (21.3%) were the most predominant species in the coproculture. For both categories, the inclusion of FMC 3 as a positive test increased the sensitivity but decreased the specificity of the method. When FMC 3 was included as anemic, the percentage of false negative was close to zero, but a greater number of treatments were applied to non-anemic animals (false positive). Most of the lambs (73%) and ewes (57%) remained in categories 1 or 2 throughout the trial. Only 5% of the lambs and 8% of the ewes were classified as the two major stages of anemia (4 and 5). The results indicate that the FMC is a safe method to be used in lambs and lactating ewes with clinical anemia from H. contortusinfection. For both categories, it was necessary to include FMC 3 as a positive condition to increase the sensitivity of the method and to reduce the risk of death of undiagnosed anemic animals (false negatives).

Performance, carcass traits and costs of Suffolk lambs finishing systems with early weaning and controlled suckling

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.

Composição tecidual e perfil de ácidos graxos do lombo de cordeiros terminados em pasto com níveis de suplementação concentrada

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%; 1% and 2% 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.

Moxidectin residues in lamb tissues: Development and validation of analytical method by UHPLC-MS/MS

The development and validation of a throughput method for the quantitation of moxidectin residues in lamb target tissues (muscle, kidney, liver and fat) was conducted using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). To achieve higher recovery of the analyte from the matrices, a modified QuEChERS method was used for sample preparation. The chromatographic separation was achieved using a Zorbax Eclipse Plus C18 RRHD column with a mobile phase comprising 5mM ammonium formate solution +0.1% formic acid (A) and acetonitrile +0.1% formic acid (B) in a linear gradient program. Method validation was performed based on the Commission Decision 2002/657/EC and VICH GL49. To quantify the analyte, matrix-matched analytical curves were constructed with spiked blank tissues, with a limit of quantitation of 5ngg-1 and limit of detection of 1.5ngg-1 for all matrices. The linearity, decision limit, detection capability accuracy, and inter- and intra-day repeatability of the method are reported. The method was successfully applied to incurred lamb tissue samples (muscle, liver, kidney and fat) in a concentration range from 5 to 200μgkg-1, which demonstrated its suitability for monitoring moxidectin residues in lamb tissues in health surveillance programs, as well as for pharmacokinetics and residue depletion studies.

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.