Níveis de energia metabolizável mantendo a relação lisina digestível: caloria em rações para suínos machos castrados em terminação

Abstract

Metabolizable energy levels maintaining digestible lysine:calorie ratio in diets for finishing barrowsABSTRACT -Forty barrows from commercial hybrids averaging initial weight of 60.1 ± 1.3 kg were used in a trial to evaluate different ME levels, maintaining the digestible lysine:calorie ratio, on the performance and carcass characteristics. A randomized block experimental design with four treatments, five replicate and two animals per experimental unit was used. The treatments consisted of four ME levels (3,100, 3,230, 3,370, and 3,500 kcal/kg) with 2.41 g of digestible lysine/Mcal of EM ratio. Animals were fed until the end of the experimental period, when the animals reached 95.46 ± 2.89 kg. It was observed linear effect of treatments on feed intake. Feed:gain ratio increased linearly as the ME levels increased. There was no treatment effect on energy efficiency, weight gain, carcass yield, backfat thickness and lean meat yield. It was concluded that increasing ME levels (3,100 to 3,500 kcal/kg, maintaining the dietary digestible lysine:calorie ratio of barrows, increase feed:gain ratio and decrease feed intake with no effect on weight gain and carcass characteristics.Key Words: carcass, energy density, finishing phase, genotype IntroduçãoO conteúdo energético das rações é um dos fatores nutricionais mais relevantes para o desempenho de suínos na fase de terminação. Em geral, a energia é o componente nutricional que mais onera a alimentação, pois a maior parte da ração é constituída por alimentos energéticos. Por isso, a busca pela eficiência na nutrição energética dos suínos, aliando ganhos biológicos e econômicos, tem sido contínua.Os suínos, especialmente na fase de terminação, tendem a alterar o consumo de ração, procurando ajustá-lo aos níveis de energia da dieta. Quanto mais elevado o nível de energia, menor o consumo voluntário. Portanto, a utilização de rações com alta densidade energética na fase de terminação torna

Performance and carcass characteristics of swine at 50 kg fed diets with different energy levels and reduced levels of crude protein

“…These data confirm the studies conducted by Rezende et al (2006), who also have observed no effect of the dietary levels of ME on this variable in animals from 60 to 95 kg.…”

“…Since no differences were observed (P>0.05) in ME intake, these data are consistent with those obtained by Trindade Neto et al (2005), who when assessing growing pigs between 23 and 48 kg of body weight have found that these animals can transform their feed intake into energy intake. These results are similar to the ones obtained by Rezende et al (2006), who have observed a reduction in the ADFI due to the increase in the energy density of diets for growing pigs (60 to 95 kg). Similarly, Santos et al (2005), when evaluating gilts fed three levels of total lysine (0.55, 0.75 and 0.95%) and three levels of ME (3100, 3250 and 3400 kcal/kg) with a content of 13% crude protein (CP) have also observed a reduction in ADFI with an increase in the content of ME.…”

“…On the other hand, Rezende et al (2006) have suggested that there was an improvement in feed:gain because thay have observed a linear increase in F:G with an icrease in the ME of diets. According to these authors, among the animal performance data usually evaluated in different experiments, the positive response of F:G to an increased energy density of the diet has been the most consistent.…”

“…Moreover, energy levels can be manipulated to directly affect the utilization of other nutrients because they are linked to the regulation of consumption by the animals (REZENDE et al, 2006) and they interfere in the digestive processes of other nutrients, mainly amino acids (ALMEIDA et al, 2007).…”

Energia líquida e ractopamina para leitoas em terminação sob altas temperaturas ambientais

“…Esse resultado é corroborado pelos Tabela 2 -Desempenho de leitoas em terminação, sob estresse por calor, alimentadas com dietas contendo níveis de energia líquida (EL) e suplementadas com ractopamina (Rac). Estas variações do CRD podem estar relacionadas aos ajustes da demanda energética dos animais, de forma que a baixa densidade energética das dietas é compensada com o aumento do consumo até que determinado nível de exigência de energia seja atingido (REZENDE et al, 2006). Provavelmente, no presente estudo, esta resposta não foi constatada, uma vez que os animais foram submetidos a temperaturas ambientais elevadas que podem ter deprimido a ingestão voluntária de alimento.…”