Effects of vitamin B6 and tryptophan on pork quality and amount of lean meat in gilts of 70–100 kg bodyweight

Supplementary tryptophan in pig diets has shown improvement in carcass traits and pork quality by reducing the animals' response to stress at slaughter. Vitamin B6 could enhance this response since it acts as an enzymatic cofactor of many tryptophan pathways. The present experiment was designed to evaluate dietary vitamin B6 supplementation and tryptophan levels on carcass traits, organ weights, abdominal fat, and pork quality of 70–100 kg gilts. Sixty-four crossbred gilts (initial bodyweight (BW) 70.52 ± 2.95 kg) were distributed in a 2 x 4 factorial scheme, consisting of two supplementary vitamin B6 levels (1 and 5 mg kg-1) and four dietary standardized ileal digestible (SID) tryptophan (Trp) levels (0.140%, 0.167%, 0.194%, and 0.221%). No significant interactions between the dietary SID Trp levels and B6 supplementation were observed on these variables. Vitamin B6 supplementation (5 mg kg-1) showed a minor reduction in meat pH measured 24 hours after slaughter and resulted in a ham yield higher than B6 basal level (1 mg kg-1). The lean meat yield increased linearly as the SID Trp levels increased in the diet. These findings suggested that vitamin B6 supplementation enhanced the pork quality and the increasing levels of SID tryptophan enhanced the lean meat yield of 70–100 kg gilts.Keywords: Carcass yield, meat colour, organ weigh

Partial replacement of DL-Methionine and methionine hydroxy analogue with betaine in diets for broiler chickens

The study evaluated the effects on the growth performance and carcass characteristics of broiler chickens of DL-Methionine (DL-Met) and methionine hydroxy analogue (MHA) supplementation and their partial replacement with betaine (Bet). Two experiments were performed from day 1 to 21 and from day 22 to 42. Broiler chickens were assigned to six treatments, in a completely randomized design and a 2 × 2 + 2 factorial arrangement, consisting of two Met sources (DL-Met and MHA), with or without Bet, and two negative controls. The six treatments consisted of i) NC-DLM: negative control for DL-Met with 7% reduction in DL-Met; ii) NC-MHA: negative control for MHA with 7% reduction of MHA, iii) DLM100: without Bet, supplemented exclusively with DL-Met reaching 100% of requirements, iv) MHA100: without Bet supplemented exclusively with MHA reaching 100% of requirements, v) DLM93+Bet: DL-Met at 93% of recommended level plus betaine; vi) MHA93+Bet: MHA at 93% of recommended level plus betaine. Growth from day 1 to 21 was not altered by methionine source or betaine supplementation. However, the negative controls had numerically less weight gain and feed conversion ratio (FCR) . Between days and 42 there were no effects on growth. Betaine could partially replace methionine without altering the growth of broiler chickens. In addition, the partial replacement of DL-Met with betaine increased body crude protein content. However, its use increased body fat content regardless of methionine source

Nitrogen balance of barrows (15-30 kg) fed low protein and different digestible isoleucine levels

Foram utilizados vinte suínos mestiços, ma- chos castrados, com peso vivo inicial médio de 22,26 ± 1,79 kg; distribuídos individualmente em gaiolas de metabolismo, em um delineamento ex- perimental de blocos ao acaso, com cinco tratamentos (0,45; 0,52; 0,59; 0,66; 0,73 % de isoleucina digestível) e quatro repetições. As dietas foram formuladas à base de milho e farelo de soja, com baixa proteína bruta (14,15 %), e diferentes níveis de isoleucina digestível. As die- tas foram umedecidas e fornecidas duas vezes ao dia (7 e 19 h) para reduzir perdas e facilitar a ingestão. O período experimental teve duração de 12 dias, sendo 7 dias para adaptação às gaiolas metabólicas e rações experimentais e 5 dias de coleta total de fezes e urina. Posteriormente, foi determinado o teor de matéria seca das fezes e o teor de nitrogênio (N) das fezes e urina, bem como o nitrogênio da uréia plasmática. Foram, então, calculados o consumo de N, excreção de N (fezes e urina), N absorvido, N retido, N absorvido/N retido, N retido/N consumido, N retido/N absorvido e excreção total de N. Obteve-se significância (p<0,05) apenas para o nitrogênio ingerido (g/kg PV 0,75 /dia), em que o modelo linear apresentou aumento nos valores de N ingerido à medida que aumentaram os níveis de isoleucina digestível nas rações.Twenty crossbred castrated barrows, averaging 22.26 ± 1.79 kg of body weight, were used. The animals were individually alloted in metabolic cages, in a randomized blocks design, with five treatments (0.45, 0.52, 0.59, 0.66 and 0.73 % of digestible isoleucine) and four replicates. The diets were based on corn and soybean meal with low crude protein (14.15 %) and different levels of digestible isoleucine. The diets were humidified and supplied twice a day (7 am and 7 pm) to reduce losses and facilitate ingestion. The experimental period lasted 12 days, being 7 days for adaptation to metabolic cages and experimen- tal diets and 5 days for total feces and urine collection. Feces were analyzed for dry matter and nitrogen (N), whereas urine samples were analyzed for N. The plasma urea nitrogen was also determined. Then, the N intake, N excretion (feces and urine), N absorbed, N retention, N retention/N intake, N retention/N absorbed and total N excretion were determined. Only N intake (g/kg BW 0.75 /day) was influenced (p<0.05) by digestible isoleucine levels, showing a linear increase on N intake as digestible isoleucine levels increased in the diets

Determinação dos valores energéticos e aminoacídicos da silagem de grãos úmidos de milho para frangos de corte

To determine the energy values of high moisture corn silage (SGUM), 120 Cobb Slow male broilers from 21 to 31 days old, with an initial average weight of 765.0 ± 1.7 g, were used, distributed in a completely randomized design, with five treatments (reference ration-RR and replacement levels of SGUM 10, 20, 30 and 40%), in six replicates of four birds each. The experimental period lasted for ten days, five for adaptation and five for collection. The method of analysis was the total excreta collection for the subsequent analysis of its apparent metabolizable energy (EMA) and nitrogen corrected EMA (EMAn) of SGUM. To determine the amino acid values, the technique of forced feeding was applied in 12 cecectomized Leghorn roosters, with an average weight of 1912.10 ± 133.73 g. Six animals received SGUM and the other six were fasted. At the end of the excreta collection period, the essential amino acid profile was determined, as well as, the true digestibility coefficients and the true digestible content of amino acids in the feed. SGUM presented average values of EMA and EMAn of 2283 and 2272 kcal/kg, respectively, and the energy values were negatively affected by the inclusion levels of SGUM. Cystine presented the lowest digestibility coefficient, whereas leucine and glutamine showed the highests digestible amino acids values.Para a determinação dos valores energéticos da silagem de grãos úmidos de milho (SGUM), foram utilizados 120 frangos de corte machos, linhagem Cobb Slow, de 21 a 31 dias de idade, com peso médio inicial de 765,0 ± 1,7 g, distribuídos em um delineamento inteiramente casualizado, com cinco tratamentos (ração referência-RR e níveis de substituição da SGUM de 10, 20, 30 e 40 %), seis repetições e quatro aves por unidade experimental. O período experimental teve duração de dez dias, sendo cinco de adaptação e cinco de coleta. O método de análise foi o de coleta total de excretas, para posterior análises de energia metabolizável aparente (EMA) e EMA corrigida pelo balanço de nitrogênio (EMAn) da SGUM. Para a determinação dos valores de aminoácidos, foi usada a técnica de alimentação forçada em 12 galos Leghorn cecectomizados, com peso médio de 1912,10 ± 133,73 g. Seis animais receberam a SGUM e os outros seis permaneceram em jejum. Ao final do período de coleta de excretas, foi determinado o perfil de aminoácidos essenciais, coeficientes de digestibilidade verdadeira e o conteúdo digestível verdadeiro dos aminoácidos no alimento. A SGUM apresentou valores médios de EMA e EMAn de 2283 de 2272 kcal/kg, respectivamente, sendo que os valores energéticos foram negativamente influenciados pelos níveis de inclusão da SGUM. A cistina apresentou o menor coeficiente de digestibilidade, enquanto a leucina e a glutamina apresentaram os maiores valores de aminoácidos digestíveis

Níveis de valina digestível para suínos machos castrados dos 15 aos 30 kg

The objective of this study was to evaluate the digestible valine levels for barrows from 15 to 30 kg of weight. In the first experiment, to determine the nitrogen balance, were used 20 barrows, averaging 22.88±1.19 kg of initial weight, individually allotted in metabolic cages in a randomized blocks design, consisting of five treatments (0.60, 0.67, 0.74, 0.81, 0.88% of digestible valine) and 4 replications. In the second experiment we determined animal performance in 40 barrows, with initial weight of 15.49±0.06 kg, submitted to the same treatments, experimental design and replicates used in the first experiment. The retained N: absorbed N ratio showed a quadratic effect, indicating 0.748% as an optimum level of digestible valine. Total N excretion showed a quadratic effect depending on the digestible valine levels, being reduced until 0.730% of digestible valine and from this level the N excretion increased again. The efficiency of valine utilization for weight gain decreased linearly as the digestible valine increased in the diets, and according to the Linear Response Plateau model was observed a reduction of this parameter up to 0.790% digestible valine. It was concluded that the level of 0.748% of digestible valine was the most appropriate when considering the retained N: absorbed N ratio, for barrows from 15 to 30 kg of live weight.O objetivo deste trabalho foi o de avaliar níveis de valina digestível para suínos machos castra- dos, dos 15 aos 30 kg de peso. No primeiro experimento, para determinação do balanço de nitrogênio, foram utilizados 20 suínos, machos castrados, com peso inicial de 22,88±1,19 kg, distribuídos individualmente em gaiolas de meta- bolismo, em delineamento experimental de blocos ao acaso, constituído de cinco tratamentos (0,60; 0,67; 0,74; 0,81 e 0,88% de valina digestível) e quatro repetições. No segundo experimento, de desempenho, foram utilizados 40 suínos, machos castrados, com peso inicial de 15,49±0,06 kg, submetidos aos mesmos tratamentos, repetições e delineamento experimental utilizados no primeiro experimento. A relação N retido:N absorvido apresentou resposta quadrática, indicando um nível ótimo de valina digestível de 0,748%. A excreção total de N apresentou efeito quadrático em função dos níveis de valina digestíveis, sendo reduzida até o nível de 0,730% de valina digestível e a partir deste nível a excreção de N aumentou novamente. A eficiência de utilização de valina, para ganho de peso reduziu de forma linear à medida que aumentaram os níveis de valina digestível nas rações, e ao utilizar o modelo linear response plateou obteve-se a redução deste parâmetro até 0,790% de valina digestível. Conclui- se que o nível de 0,748% de valina digestível foi o mais adequado, ao se considerar o N retido: N absorvido, para suínos machos castrados dos 15 aos 30 kg de peso