Real-time ultrasonography (RTU) was used to measure the longissimus dorsi muscle (LM) volume in vivo and to predict the carcass composition of rabbits. For this, 63 New Zealand White × Californian rabbits with 2093±63 g live weight were used. Animals were scanned between the 6th and 7th lumbar vertebrae using an RTU equipment with a 7.5 MHz probe. Measurements of LM volume were obtianed both in vivo and on carcass. Regression equations were used for the prediction of carcass composition and LM volume using the LM volume measured obtained with RTU (LMVU) as independent variable. Carcass meat, bone and total dissectible fat weights represented 780, 164 and 56 g/kg of the reference carcass weight, respectively. Regression equations showed a strong relationship between LMVU and the correspondent volume in carcass. Furthermore, LMVU was also useful in predicting the amounts of carcass tissues. It is possible to predict LM volume in the carcass using the LM volume measured in vivo by RTU. The amount of carcass tissues can be predicted by the LM volume measured in vivo by RTU.

Três experimentos foram realizados para avaliar os efeitos de dietas formuladas com 53% de trigo ou centeio, suplementadas ou não com a enzima xilanase (0,06%), sobre a digestibilidade de nutrientes e a energia metabolizável das dietas e sobre o desempenho e desenvolvimento do trato digestivo de frangos de corte. Como testemunha foi usada uma dieta com 53% de milho. No primeiro experimento, as digestibilidades da matéria seca, matéria orgânica e gordura e energia metabolizável corrigida para o nitrogênio (EMAn) das dietas com centeio foram menores que daquelas com trigo (2.556 kcal/kg vs 2.842 kcal/kg) e menores no conjunto dessas dietas que na dieta com milho (2.684 kcal/kg vs 3.010 kcal/kg). A digestibilidade da matéria orgânica e a EMAn das dietas com centeio também foi inferior às da dieta com trigo. A suplementação com xilanases não afetou a utilização digestiva das dietas com centeio ou com trigo. No segundo experimento, nos frangos alimentados com as dietas com centeio, o menor ganho de peso e consumo de EMAn e a pior conversão alimentar ocorreram entre os 8 e os 35 dias de idade. A conversão alimentar foi de 2,17 para as dietas com centeio e 1,88 para a dieta com milho. A adição de xilanases às dietas com centeio ou trigo não melhorou a conversão alimentar. Nos frangos alimentados com as dietas com centeio durante 31 dias, o duodeno-jejuno e íleo foram maiores e o rendimento de carcaça menor que nos frangos alimentados com a dieta testemunha (71,6% vs 74,4%). As dietas com trigo não afetaram essas características. Os pesos do pâncreas e do fígado também não foram alterados pelas dietas.

Three trials with were conducted to evaluate the effects of diets with 53% rye (diet C) or 53% wheat (diet T) supplemented or not with xylanase enzymes (0.06%) on nutrient digestibility and metabolizable energy and the performance and development of the broiler chicken digestive tract. A diet with 53% corn was used as control. In trial 1, dry matter, organic matter and apparent fat digestibilities corrected for nitrogen (EMAn) were lower in rye diets than in wheat diets (2556 kcal/kg vs 2842 kcal/kg) and were lower in the set of these diets than in the control diet. The organic matter digestibility and EMAn in the rye were also lower than those of the wheat diets. Xylanase supplementation did not affect the digestive use of the rye or wheat diets. In trial 2, growing broiler chickens fed the rye diets showed the lowest weight gain and EMAn intake and the worst feed conversion ratio between 8 and 35 days of age. The feed conversion ratio was 2.17 with rye diets and 1.88 with the corn diet. Xylanase supplementation on rye or wheat based diets did not improve feed conversion. In trial 3, birds fed on rye diets for 31 days showed longer duodenum-jejunum and ileum and lower carcass yield than birds fed the control diet (71.6% vs 74.4%). The wheat based diets did not affect these parameters. Pancreas and liver weights were not affected by the feeds.