ABSTRACT We aimed to verify whether age influences the biochemical profile of healthy lambs during the first four months of life by characterizing the dynamics of its parameters and verifying whether there are differences between the profiles of growing animals and the reference values established for adults. Blood samples of 34 ½ White Dorper × ½ Suffolk female lambs were collected at 30, 60, 90, and 120 days of age, and the serum concentrations of total proteins, total globulins, albumin, urea, creatinine, bilirubins (total, conjugated, and unconjugated), total cholesterol, triglycerides, glucose, gamma-glutamyltransferase, aspartate aminotransferase, and creatine kinase were determined. Descriptive statistics of these parameters were performed to compare them with the reference intervals used for adult sheep. Age influenced the dynamics of all the biochemical parameters between 30 and 120 days of age. Moreover, except for the total, conjugated and unconjugated bilirubins, total cholesterol, and aspartate aminotransferase means, the values of the lambs differed from the reference intervals established for adults. In conclusion, there is an influence of age on biochemical parameters in healthy female lambs in the first four months of life, and often the biochemical parameters of young animals differ from those of adults. Therefore, the interpretation of tests performed on growing animals should be made based on specific reference intervals for this age group.

ABSTRACT The objective of this study was to develop a model for calculation and analysis of production costs of lamb and, from that, to elaborate a production cost index. Panel meetings were held in five regions of the state of São Paulo, Brazil, to define technical features of representative properties of lamb production, taken as a basis for the preparation of the cost calculation model. Then the model for production cost calculation was built. The third step consisted of monitoring prices of inputs used, calculating production costs along the studied period, and generating the cost index, by the Laspeyres model. Lastly, questionnaires were applied to sheep producers, to validate the cost index. The model for production cost calculation was planned to be of easy utilization by farmers, and simultaneously faithful to the theoretical principles. The adopted scheme of cost allocation followed the classification of "variable", "fixed operating", and "income of factors". We generated cost indexes for each of the five studied regions, which were then aggregated in a state index, by weighting regional indexes by flock size. More than 97% of the answers to the validation questionnaires were positive, so we considered that the index reached a high level of approval. The application of Economic Theory is essential for the development of cost calculation models. The developed model has potential to generate important information that can help producers to make decisions. It can work in many contexts, and it can even be adapted to other livestock species. The production cost index for lamb was approved and can collaborate with the organization of the sheep agroindustrial system.

Objetivou-se analisar os custos e a rentabilidade de sistemas de produção de ovinos em pastagem sob três estratégias de suplementação de cordeiros lactentes: (1) creep grazing de trevo branco; (2) creep feeding; e (3) sem suplementação. Utilizaram-se dois métodos de análise financeira: análise anual (de curto prazo) e de fluxo de caixa (de longo prazo). Os custos foram segmentados em variáveis, fixos, operacionais e totais. O fator de produção que exerceu maior influência no custo variável da produção foi a alimentação, e no custo total foi o custo de oportunidade do capital imobilizado. O sistema com creep grazing não apresentou resultados econômico-financeiros superiores aos com creep feeding.

The objective was to analyze production costs and profitability of grazing sheep productions systems under three strategies of lamb's supplementation: (1) white clover on creep grazing; (2) creep feeding; and (3) not supplemented. Two methods of financial analyses where used: annual (short term) and cash flow (long term). Costs were classified into variable, fixed, operational and total. Results showed that feeding and opportunity cost over investment was the most important production factors at variable and total costs, respectively. System with creep grazing supplementation did not show greater economic financial results over creep feeding supplementation system.