The objective of this study was to evaluate the reduction of crude protein diets on nitrogen balance, urinary pH and blood parameters of starter pigs. The average initial weight of the animals was 18.5 ± 0.73 kg. Two digestibility experiments were conducted, one in environmental conditions of stress (28.77 ˚ C) and another in thermal comfort condition (18.13 ˚ C). In both experiments, the animals were distributed in randomized blocks with four decreasing levels of crude protein (20.5, 19.4, 18.3 and 17.2%) and four replications, totaling 16 experimental units in each experiment, each represented by an animal, totaling 32 animals. The methodology used was the total collection of feces and urine was collected and filtered daily. To assess blood parameters, samples were obtained by jugular vein puncture. The parameters evaluated were ingested nitrogen, excreted O objetivo deste trabalho foi avaliar a redução da proteína bruta em rações sobre o balanço de nitrogênio, pH urinário e parâmetros sanguíneos de suínos na fase inicial. O peso médio inicial dos animais foi de 18,5 ± 0,73kg. Foram realizados dois experimentos de digestibilidade, sendo um em condições de ambiente de estresse (28,77˚C) e outro conforto térmico (18,13˚C). Em ambos os experimentos os animais foram distribuídos em um delineamento experimental de blocos ao acaso com quatro níveis de proteína bruta (20,5; 19,4; 18,3 e 17,2%) e quatro repetições, totalizando 16 unidades experimentais em cada experimento, sendo cada uma representada por um animal, totalizando 32 animais. A metodologia utilizada foi a coleta total de fezes, e a urina coletada e filtrada diariamente. Para avaliar os parâmetros sanguíneos, as amostras foram obtidas mediante punção na veia jugular. Os parâmetros avaliados foram nitrogênio ingerido, excretado nas fezes e na urina, absorvido, retido, retido/absorvido, excreção total, utilização líquida de proteína, pH da urina, colesterol, triglicerídeos, glicose, uréia e creatinina no plasma sanguíneo. Conclui-se que a redução do nível de proteína da dieta, de 20,5 a 17,2%; é uma alternativa eficiente para reduzir a quantidade de nitrogênio excretado pelos suínos em condição de estresse térmico. Para condição de conforto térmico os suínos apresentaram maiores concentrações de creatinina e colesterol plasmático. ResumoPalavras-chave: Aminoácidos. Ambiente térmico. Metabolismo de nitrogênio.

The objective of this study was to evaluate the growth performance of two crossbreed genetic groups, ½ Nelore ½ Angus and ¼ Nelore ¼ Angus ½ Guzera, which originate from the rotational crosses of Nellore cows with Angus bulls and ½ Nellore ½ Angus cows with Guzera bulls, respectively. The growth performance was evaluated at the end of the yearling and feedlot stages, and carcass characteristics were evaluated after the slaughter. A completely randomized trial design was used, with 12 cows in each group. The yearling stage lasted 270 days, and the cattle were fed with pasture of Brachiaria brizantha 'Marandu' with 2.0 UA ha -1 and a forage allowance of 2.5 kg of dry matter (DM) per 100 kg of live weight (LW), during this stage the animals, with an average age of 365 ± 10 days, received protein and energy supplementation ad libitum. After the yearling stage, the cows were confined until they reached the age of 22-24 months and received 6.0 kg DM of sugar cane + urea and 4.0 kg DM of concentrate, with 150 g kg -1 of crude protein (CP), daily during 90 days. The daily average weight gain (DAWG) during the yearling stage was higher for the ½ Nelore ½ Angus group. The ¼ Nelore ¼ Angus ½ Guzera group reached higher slaughter weight because they had higher DAWG during the feedlot stage (1.022 vs. 728 g dia -1 ). No significant difference (P>0.05) was found between the groups when the hot carcass weights were compared. The ½ Nelore ½ Angus group reached a higher carcass weight percentage (53 vs. 50 %) and subcutaneous fat thickness (4.3 vs. 4.0 mm).

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ObjectiveEvaluate the partial replacement of soybean meal with different protein sources in piglet feed during the nursery phase in terms of digestibility of feed, nitrogen balance, growth performance and blood parameters.MethodsExperiment I involved 24 crossbred entire male pigs with an initial body weight (BW) of 18.28±0.7 kg and used a randomized complete block design consisting of 3 treatments (fish meal, FM; soybean protein concentrate, SPC; and soybean meal, SBM) and 8 replicates, with 1 pig per experimental unit. Experiment II involved 1,843 crossbred male and female pigs with an initial BW of 6.79±0.90 kg and was based on a completely randomized design with a 2×3 factorial arrangement (2 sexes and 3 protein sources) and 13 replicates.ResultsThe results of Exp. I indicate effects (p<0.05) of dietary protein sources on digestible protein (FM, 17.84%; SPC, 16.72%, and SBM, 18.13%) and on total nitrogen excretion (TNE, g/kg BW0.75/d) in which pigs fed with SBM-based feed had TNE values that were 5.36% and 3.72% greater than SPC and FM, respectively. In the Exp. II, there was difference (p<0.01) between sexes in the pre-starter I and starter phases, and total period in average daily feed intake (ADFI), which were greater in females, and between the protein sources, ADFI, final weight and daily weight gain. For urea in the pre-starter II and starter phases and glucose in the pre-starter II phase, there was a difference (p<0.05) between protein sources and between sexes, in starter phase in urea concentrations (females: 57.11 mg/dL and males: 50.60 mg/dL).ConclusionThe use of SBM as only protein source influences larger TNE (g/kg BW0.75/d), reduces the growth performance of piglets and increases plasma urea concentrations in pre-starter II phase.

Two experiments were carried out to determine the nutritional value of a dehydrated cassava co-product (DCC) and its effects on the performance and blood variables of piglets fed with different levels of DCC. In experiment I, a digestibility assay was performed and 30 whole-male crossbred piglets with initial body weight of 18.00 ± 0.673 kg were housed individually in metabolism cages and distributed in a completely randomized experimental design with 5 treatments, 6 replicates and one animal per experimental unit. A reference diet was formulated to meet the category nutritional requirements and the different levels of DCC replacement (6, 12, 18 and 24%) were used to replace the reference diet and composed the treatments. In experiment II, 120 piglets (60 whole males and 60 females) were used, with initial body weight of 13.05 ± 1.59 kg, distributed in a randomized complete block design with 5 treatments, 6 replicates and 4 animals per experimental unit. Treatments consisted of five feeds with increasing inclusion levels (0, 3, 6, 9 and 12%) of the DCC. The feed based on corn and soybean meal were formulated to meet the recommended levels in starting piglets feeding. The data were submitted for statistical analysis and, when presenting significant difference, the averages were compared by the Dunnet's test at 10 % significance. In the digestibility assay, the values of DCC's digestive energy and metabolizable energy of 3,022 and 2,984 kcal kg -1 in natural matter, respectively, were found. There was no significant effect (p > 0.10) of inclusion levels of DCC on the final weight and daily gain of weight however we observed a quadratic effect (p < 0.10) of the DCC levels on daily feed intake and feed conversion. For the analysis of blood parameters, the results showed that there was no effect (p > 0.10) of DCC levels on glucose and blood urea in the different treatments. The use of the dehydrated cassava co-product can be an energetic alternative to piglets in starting phase and can be used up to 12 %. Key words: Alternative food. Nutrition. Swine production. ResumoDois experimentos foram conduzidos, objetivando-se determinar o valor nutricional do Coproduto Desidratado de Mandioca (CDM) e seus efeitos no desempenho e nas variáveis sanguíneas de leitões alimentados com diferentes níveis do CDM. No experimento I, realizou-se um ensaio de digestibilidade e foram utilizados 30 leitões híbridos, machos inteiros, com peso vivo inicial de 18,00 ± 0,673 kg, alojados individualmente em gaiolas de metabolismo, e distribuídos em um delineamento experimental inteiramente casualizado, com 5 tratamentos, 6 repetições e um animal por unidade experimental. Uma ração referência foi formulada para atender as exigências nutricionais da categoria e diferentes níveis de substituição do CDM (6, 12, 18 e 24%) foram utilizados para substituir a ração referência, compondo os tratamentos. No experimento II, foram utilizados 120 leitões (60 machos inteiros e 60 fêmeas), com peso vivo inicial de 13,05 ± 1,59 kg, distribuídos em um ...