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Since nutritional requirements are increased at the end of gestation to meet the demands of the pregnant uterus, pregnant beef cows are susceptible to mobilization of body reserves (mainly fat and amino acids (AAs)) and to alter the metabolism of nutrients in the liver and muscle to support such demands. The objective of this study was to evaluate the effect of CP supplementation on maternal nutrient metabolism in the late gestation of beef cows grazing a low-quality pasture. Forty-three pregnant Nellore cows gestating male fetuses (average age = 6 years; average weight = 544 kg) at 193 ± 30 (mean ± SD) days (d) of gestation were divided into eight groups (experimental units, with four to five cows each). Treatments were (1) control (CON, n = 4): pasture-based (PB) diet without CP supplementation and (2) supplemented (SUP, n = 4): PB diet daily supplemented with 2 g/kg of BW of a 43.5% CP supplement. Liver and skeletal muscle biopsies were performed at 265 days of gestation and samples were collected for mRNA expression. On day 280 of gestation, blood samples were collected to assess plasma levels of AA. The CON-fed cows tended to have greater (P = 0.057) total circulating AA than SUP-fed cows. The circulating glycogenic AA was greater (P = 0.035) in CON than in SUP cows. CON cows was greater for histidine (P = 0.015), methionine (P = 0.007) and alanine (P = 0.036) than SUP cows. The CON- and SUP-fed showed no differences for gluconeogenesis, fatty acid transport and signaling axis markers in the liver. The mRNA expression of markers for skeletal muscle synthesis, p7056k (P = 0.060) and GSK3B (P = 0.096), tended to be greater in cows from CON than SUP group. No differences were found for mRNA expression of markers for skeletal muscle degradation. We conclude that CP supplementation to CP-restricted late-pregnant beef cows reduces the maternal tissue mobilization and changes the profile of plasma circulating AA and the mRNA expression of markers for the synthesis of skeletal muscle tissue.

Para avaliar a substituição do feno Tifton 85 pelo caroço de algodão como fonte de fibra na dieta foram utilizados 24 bezerros da raça Holandesa, distribuídos em dois grupos. O grupo-feno recebeu feno e concentrado separados, fornecidos à vontade, e o grupo- algodão recebeu caroço de algodão incorporado ao concentrado (13,5%), à vontade. O consumo de alimentos, o peso, as alturas da cernelha e do íleo, as circunferências torácica e abdominal, a concentração de glicose sangüínea, as concentrações de acetato, propionato e butirato, o pH do fluido ruminal e os pesos dos compartimentos do estômago foram mensurados. O consumo de alimentos, o desenvolvimento ponderal dos animais, as concentrações de acetato, propionato e butirato, o pH do fluido ruminal, as concentrações de glicose sangüíneas e o peso dos compartimentos do estômago foram semelhantes entre os tratamentos (P>0,05). À necropsia, não foram observadas alterações sugestivas de intoxicação por gossipol. Concluiu-se que o caroço de algodão substituiu, sem prejuízos, o feno como fonte de fibra na dieta de bezerros.Twenty-four Holstein calves divided into two groups were used to evaluate Tifton 85 hay or whole cotton seed as fiber source in their diets. One group received Tifton 85 hay and concentrate ad libitum (hay group) and the other received ad libitum (cotton group) only concentrate with whole cotton seed incorporated (13,5%). Feed intake; weight; whither and ileum heights; thoracic and abdominal circumferences; acetate, propionate and butyric concentrations; pH of ruminal content; blood glucose; and rumen, reticulum, omasum and abomasum weights were measured. Feed intake; animal performance; acetate, propionate and butyric concentrations; pH of ruminal content; blood glucose and weight of stomach compartments did not differ between the groups (P>0.05). No clinical evidence of gossypol intoxication was observed. It was concluded that whole cotton seed replaced hay as fiber source in the diets of calves.

Utilizaram-se 42 bezerros da raça Holandesa para avaliação do consumo de mistura mineral (MM), até os 60 dias. Os animais foram distribuídos em três grupos conforme o sucedâneo fornecido: grupo soro/leite + MM (SLMM); grupo soro + MM (SMM); e grupo soja/leite + MM (SOMM). Os animais receberam concentrado, feno, MM e água à vontade. A avaliação do ganho de peso foi feita semanalmente. A concentração de glicose plasmática foi medida aos 7, 14 e 21 dias de vida, antes do fornecimento da dieta, e às 3, 6 e 9 horas após a primeira refeição. Realizaram-se hemogramas semanais para avaliações clínicas. Aos 30 e aos 60 dias, colheram-se sangue e urina de cinco animais de cada grupo, os quais foram sacrificados para obtenção de fragmentos do fígado, para análises de minerais. Os animais do grupo SMM apresentaram menores consumos de concentrado e matéria seca total (MST) entre a sexta e oitava semanas (PForty-two Holstein calves were used to evaluate the mineral supplement (MS) intake up to 60-day-old. The calves were divided into three groups, according to the milk replacer: whey/milk + MS (WMMS); whey + MS (WMS) and soy/milk + MS (SMMS). Commercial calf starter, hay, MS and water were offered "ad libitum", and the intake was measured daily. Body weight was monitored once a week and blood glucose levels were quantified on 14, 21 and 28-day-old and also before the supply of the diets, 3, 6 and 9 hours after feeding. Blood samples were collected weekly for blood count. On 30 and 60-day-old, five calves of each group had blood and urine samples collected for serum copper determination. After then, the animals were slaughtered and liver fragments were analyzed for minerals contents. It was found that between the sixth and eighth weeks, the calves from WMS group decreased the intake (P

Quinze bezerros da raça Holandesa, desaleitados aos 30 dias de idade, foram utilizados para avaliar os efeitos da inclusão de fontes protéicas alternativas, em substituição às proteínas do leite integral, na formulação de sucedâneos do leite. Os animais foram divididos em três grupos: o grupo controle (C) - recebeu leite em pó integral reconstituído; o grupo sucedâneo SL (soro/leite) recebeu 41,6% da proteína bruta (PB) vinda do concentrado protéico de soro (CPS), 23,1% do soro de leite e 35,3% do leite em pó integral; e o grupo sucedâneo S (soro) recebeu 68% da PB vinda do CPS e 32% do soro de leite. O consumo de concentrado, feno, sal mineral e água foi mensurado diariamente, enquanto o ganho de peso foi avaliado semanalmente. Não houve diferença (P>0,05) para o consumo de concentrado, sal mineral e água entre os grupos, nos períodos avaliados. O consumo de feno e o ganho de peso foram inferiores nos animais do grupo S (PThe effects of alternative protein sources replacing whole milk proteins in milk replacer formulation were evaluated. Fifteen Holstein calves, weaned at 30 days of age, were used to evaluate the intake of concentrate, hay, mineral salt and water, and live weight gain. Animals were divided in three experimental groups: control group (C) - fed whole milk; milk replacer WM group (whey/milk) - fed on 41.6% of crude protein (CP) provided by whey protein concentrate (WPC), 23.1% by whey and 35.3% by whole milk; and milk replacer W group (whey) - fed on 68% of CP provided by WPC and 32% by whey. Starter, hay, mineral and water intakes were daily measured, whereas live weight was weekly recorded. Starter, mineral and water intakes were not different (P>0.05) among the experimental groups. Hay intake and live weight gain were lower (P