RESUMOO objetivo deste estudo foi verificar a influência do colostro nos parâmetros bioquímicos séricos em cordeiros recém-nascidos. Foram colhidas amostras sanguíneas de 28 cordeiros, determinando-se os indicadores proteicos, energéticos, de função renal, bilirrubinas e as enzimas aspartato aminotransferase (AST), gamaglutamiltransferase (GGT) e creatina quinase (CK), nos momentos pré e pós-colostro. Os dados foram analisados comparando-se a variabilidade dos parâmetros entre os dois momentos. Houve elevação (P<0,001) das concentrações de proteínas totais, em resposta ao forte aumento (P<0,01) dos teores de globulinas totais e ao leve decréscimo (P<0,05) da concentração de albumina, após a ingestão colostral. Também foram observados maiores valores de bilirrubinas total e direta (P<0,001), e variação dos metabólitos renais, com elevação dos níveis de ureia (P<0,01) concomitante à redução dos valores de creatinina (P<0,001), no momento pós-colostro. Houve aumento (P<0,001) da glicemia, de colesterol total e triglicerídeos, bem como das atividades enzimáticas (P<0,001) de AST e GGT, entre os momentos avaliados. Conclui-se que a dinâmica do perfil bioquímico em cordeiros recém-nascidos sofre o efeito da ingestão de colostro e da adaptação das funções fisiológicas à vida extra-uterina. Os valores dos parâmetros variam marcadamente no período pós-natal, sendo recomendável a utilização de valores de referência próprios para esta fase. PALAVRAS-CHAVE: amamentação, bioquímica clínica, neonato, ovino, sangue. PRE AND POST-COLOSTRAL DYNAMICS OF BIOCHEMICAL PARAMETERS IN LAMBS ABSTRACTThis study aimed to verify the influence of colostrum in serum biochemical parameters in newborn lambs. Blood samples were taken of 28 lambs, determining the protein, energy and kidney function indicators, bilirrubins and the enzymes aspartate aminotransferase (AST), gammaglutamyl transferase (GGT) and creatine kinase (CK), in pre and post-colostrum moments. The data were analyzed comparing the variability of the parameters between the two moments. There was an elevation (P<0.001) in total protein concentrations, in response to substantial increase (P<0.01) in total globulin levels, and a slight decrease (P<0.05) in albumin concentration, after colostral intake. We also observed higher values of total and conjugated bilirubins (P<0.001), and variation of kidney metabolites, with an elevation of urea levels (P<0.01) concomitant to decrease of creatinine values (P<0.001) in the postcolostrum moment. There was an increase (P<0.001) in glycemia, total cholesterol and triglycerides, as well as of

The objective of this study was to evaluate the carcass and meat traits, and the non-carcass components of crossbred Dorper lambs fed diets with increasing levels of urea (0.0, 0.5, 1.0, and 1.5% of dry matter – DM). The experimental design was completely randomized with four treatments (urea inclusion levels) and six replicates per treatment. Lambs were fed ad libitum for 56 days and slaughtered at 37.9 ± 5.1 kg of body weight (BW). The weight and yield of carcass before and after cooling were not influenced by urea levels, with average values of 16.9 kg and 44.6% for cold carcass weight and yield. Urea levels did not affect the morphometric measurements, the fat deposition on the carcass, the weight of carcass cuts and the weight of non-carcass components. There was a quadratic effect of urea levels on the loin yield, which may achieve maximum value of 11.31% with the inclusion of 0.84% DM urea in the feed. The pH and the color coordinates L* (brightness), a* (red intensity) and C* (saturation) of the meat also showed quadratic response to the urea levels, where in the minimum value of 5.53 for pH, maximum value of 48.67 for L* and minimum values of 14.04 and 16.21 for a* and C* may be obtained by including 0.53 to 0.70% DM urea in the ration. The inclusion of 0.84% DM urea in the ration is recommended to obtain maximum yield of loin and meat with attractive characteristics to the consumer, which is characterized by high red intensity and brightness. If consumers have preference for lamb meat with a more intense red color, the inclusion of 1.5% DM urea should be considered in the ration formulation.

-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.

Feed intake and efficiency, animal performance, and protein and energy metabolism were studied in lambs that were fed on increasing levels of urea (0.0, 0.5, 1.0, and 1.5% of dry matter [DM]). A completely randomized design was used, with four treatments (urea levels) and six replicates. The lambs were fed ad libitum for 56 days until they reached an average body weight of 35 kg. The rations were composed of 34% Tifton 85 hay (Cynodon spp.) and 66% concentrate. Crude protein (CP) constituted 17% of the diet on a dry matter basis, and total digestible nutrients (TDN) accounted for 65%, on average. The dry matter intake (DMI) and crude protein intake (CPI) were not influenced by the urea levels in the diet, presenting average values of 1.175 and 0.206 kg animal -1 day -1 , respectively. The average daily gain (ADG), feed conversion ratio (FCR) and gross feed efficiency (GFE) were also not influenced by urea levels (0.225 kg day -1 , 5.33 kg DM kg gain -1 and 0.195 kg gain kg DM -1 , respectively). Except for urea and glucose concentrations, blood parameters did not change with increasing urea in the diets. The mean values for total protein, albumin, globulin and creatinine in the serum were 7.11 g dL -1 , 3.36 g dL -1 , 3.75 g dL -1 and 0.91 mg dL -1 , respectively. Serum urea decreased linearly and serum glucose increased linearly with urea levels in the diet. The addition of 1.5% of urea to the diets did not change feed intake and efficiency or animal performance, and did not cause metabolic disorders in feedlot lambs in the finishing phase. Key words: Blood. Finishing. Glucose. Nitrogen. Sheep. ResumoAvaliou-se o consumo de alimento, o desempenho animal, a eficiência alimentar, e o metabolismo proteico e energético de cordeiros alimentados com rações contendo níveis crescentes de ureia (0,0; 0,5; 1,0; 1,5% da matéria seca -MS). O delineamento foi inteiramente casualizado com quatro tratamentos (níveis de inclusão de ureia) e seis repetições por tratamento. Os cordeiros foram alimentados à vontade por 56 dias até atingirem peso corporal (PC) médio de 35 kg. As rações foram compostas por 34% de feno de Tifton 85 (Cynodon spp.) e 66% de concentrado, com 17% de proteína bruta (PB) e 65% de nutrientes digestíveis totais (NDT), em média, com base na matéria seca (MS). O consumo de matéria seca (CMS) e de proteína bruta (CPB) não foram influenciados pelos níveis de inclusão de ureia na ração, apresentando valores médios de 1,175 e 0,206 kg animal -1 dia -1 . O ganho médio diário (GMD), a e 0,91 mg dL -1 . A ureia sérica apresentou resposta linear decrescente, enquanto a glicose sérica de apresentou resposta linear crescente ao aumento da inclusão de ureia. A inclusão de até 1,5% de ureia na MS em rações isoproteicas não afeta o consumo de alimento, o desempenho e a eficiência alimentar, e não causa prejuízos metabólicos em cordeiros confinados na fase de terminação. Palavras-chave: Glicose. Nitrogênio. Ovinos. Sangue. Terminação.

-The influence of early weaning and concentrate supplementation strategies on sward characteristics, forage chemical composition and lamb productivity were evaluated in four production systems on Tifton-85 pasture: suckling lambs not supplemented until slaughter; suckling lambs supplemented with concentrate in creep feeding until slaughter; early-weaned lambs not supplemented until slaughter; and early-weaned lambs supplemented with concentrate until slaughter. Structural, morphological and productive characteristics of pasture were measured. The forage was chemically analyzed to estimate its composition. Lambs average daily gain and productivity were calculated. Sward height, forage and morphological components mass were lower in systems without weaning. Forage production was higher in systems with supplementation. Higher levels of neutral and acid detergent fiber were observed in forage ingested by lambs in creep feeding and by weaned and unsupplemented lambs. Average daily gain was higher for lambs in creep feeding (275 g/d) and lower for the weaned and unsupplemented animals (57 g/d). Productivity was higher for weaned and supplemented lambs (21 kg lamb body weight, BW gain/ha/d). Lower productivity was observed in systems without supplementation (5 kg lamb BW gain/ha/d on average). Ewes modify the sward conditions improving the pasture characteristics and the quality of forage produced. Changes in sward conditions affect the chemical composition of forage ingested by lambs. Early weaning may be an alternative to maximize pasture utilization in small areas. Concentrate supplementation may increase lamb performance and productivity in grazing systems. If the objective is to improve lamb individual performance, creep feeding should be used.

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RESUMO.O objetivo deste estudo foi avaliar o comportamento ingestivo de cordeiros em pastagem de Tifton-85 (Cynodon spp.) em três sistemas de produção: cordeiros desmamados aos 60 dias de idade e mantidos em pastagem; cordeiros mantidos com suas mães em pastagem; e cordeiros mantidos com suas mães em pastagem e suplementados em creep feeding. O delineamento foi em blocos ao acaso com três repetições, utilizando quatro cordeiros-teste por repetição. Na pastagem, avaliou-se a altura, a massa, a composição morfológica e bromatológica da forragem. Na avaliação do comportamento ingestivo registrou-se, do nascer ao pôr do sol, o tempo despendido nas atividades de pastejo, ruminação, ócio, amamentação e alimentação no creep feeding. Avaliou-se, também, a taxa de bocados ao pastejo. Os cordeiros permaneceram maior tempo em pastejo, e os suplementados despenderam menor (p < 0,05) tempo nessa atividade. Cordeiros não-suplementados apresentaram maior (p < 0,05) tempo de pastejo e menores (p < 0,05) tempos de ruminação e ócio pela manhã. A suplementação em creep feeding alterou (p < 0,05) a distribuição das atividades de pastejo e ruminação, indicando efeito substitutivo de forragem pelo concentrado. Concluiu-se que os sistemas de produção influenciaram o comportamento ingestivo dos cordeiros, não tendo alterado a taxa de bocados destes. Palavras-chave: creep feeding, desmame, pastejo, ruminação, taxa de bocado, Cynodon spp.ABSTRACT. Intake behavior of lambs in three production systems on Tifton 85 pasture. The objective of this study was to evaluate the intake behavior of lambs on Tifton 85 pasture (Cynodon spp.) in three production systems: sixty-days-old weaned lambs kept on pasture; lambs kept with their mother on pasture; lambs kept with their mother on pasture in creep feeding. Systems were allocated in a completely randomized blocks design with three replicates and four lambs per replicate. Pasture sward surface height, forage dry matter, and morphological and nutritional characters were assessed. Intake behavior was observed from dawn to dusk. The study assessed the time animals spent in the following activities: grazing, ruminating, idling, suckling, and staying in creep feeding. Bite rate was also evaluated. Lambs spent most of their time grazing, but the supplemented ones spent less time (p < 0.05) in this activity. Non supplemented lambs spent more time grazing (p < 0.05) and less time (p < 0.05) ruminating and idling in the morning than in the afternoon. Supplementation in creep feeding altered (p < 0.05) distribution of grazing and rumination, indicating a substitutive effect of pasture by concentrate. Sheep production systems affected the intake behavior of lambs, but did not affect the bite rate.

ResumoNo Brasil, a produção animal a pasto é privilegiada pelas extensas áreas de pastagens disponíveis e pelos baixos custos de produção comparada a outros sistemas alimentares. Entretanto, as pastagens nativas com ausência de manejo adequado podem apresentar severas deficiências nutricionais, e as pastagens cultivadas, manejadas erroneamente, tendem à degradação. O uso de leguminosas forrageiras tem potenciais benefícios ao ambiente pastoril, como incorporação de nitrogênio ao sistema, aumento da capacidade de suporte e qualidade de pastagens quando em consórcio com gramíneas, além