Níveis de energia líquida e ractopamina para leitoas em terminação sob conforto térmico

Abstract

RESUMO -Objetivou-se com este estudo avaliar níveis de energia líquida e ractopamina em dietas para leitoas em terminação sob conforto térmico. Foram utilizadas 40 leitoas com peso inicial de 67,4 ± 3,4 kg, distribuídas em delineamento de blocos ao acaso em esquema fatorial 2 × 4, composto de dois níveis de ractopamina, 0 e 20 ppm, em combinação aos níveis de energia líquida de 2.300; 2.424; 2.548 e 2.668 kcal/kg de ração, com cinco repetições, considerando cada animal uma unidade experimental. O período experimental teve duração de 28 dias. A temperatura do ar, a umidade relativa, a temperatura de globo negro e o índice de temperatura de globo e umidade foram de 21,5 ± 2,8ºC, 91,7 ± 6,8%, 21,7 ± 2,9ºC e 70,1 ± 3,7, respectivamente. Houve interação entre níveis de energia líquida e ractopamina, uma vez que a inclusão de 20 ppm de ractopamina em dietas contendo 2.668 kcal de energia líquida/kg de ração ocasionou redução da espessura de toucinho e aumento da porcentagem de carne magra e do índice de bonificação de carcaças. A inclusão de 20 ppm de ractopamina proporcionou aumento do ganho diário de peso e melhora na conversão alimentar, proporcionando maior peso de carcaça quente e aumentando a quantidade de carne magra nas carcaças. Dietas suplementadas com 20 ppm de ractopamina melhoram o desempenho e aumentam a produção de carne em leitoas em terminação. A ractopamina é ineficiente em reduzir a deposição de gordura e aumentar o percentual de carne magra na carcaça de leitoas alimentadas com dietas contendo baixa concentração de energia. O nível de 2.300 kcal de energia líquida/kg de ração atende à exigência nutricional de leitoas em terminação sob conforto térmico.Palavras-chave: aditivo, ambiente térmico, carcaça, desempenho Net energy and ractopamine levels for finishing gilts under thermal comfortABSTRACT -This research was conducted to evaluate the net energy and ractopamine levels in the diet of finishing gilts kept under thermal comfort conditions. Forty gilts were used, with initial weight of 67.4 ± 3.4 kg, distributed in a randomized blocks design in a 2 × 4 factorial scheme composed of two levels of ractopamine, 0 and 20 ppm, combined with net energy levels of 2,300; 2,424; 2,548 and 2,668 kcal/kg of feed, with five replications, considering each animal per experimental unit.The experimental period lasted 28 days. Air temperature, relative humidity, black globe temperature, and black globe temperature and humidity index were 21.5 ± 2.8ºC, 91.7 ± 6.8%, 21.7 ± 2.9ºC and 70.1 ± 3.7, respectively. There was interaction between net energy levels and ractopamine, once the inclusion of 20 ppm of ractopamine in diets with 2,668 kcal of net energy/kg of feed resulted in a decrease in backfat thickness and consequently an increase in lean meat percentage and in carcass allowance index. The inclusion of 20 ppm of ractopamine caused an increased in daily weight gain, improved feed gain ratio, providing higher hot carcass weight and increasing the lean meat amount in carcasses. Diets supplemented with 20 ppm of rac...

Net energy for 60- to 120-kg pigs fed low-crude protein diets

“…Contrary to the fi ndings of MOURA et al (2011), who reported no effect of NE content on ADG of 60-to 90-kg gilts, the results of our studies indicate that dietary NE content may affect the performance of pigs fed low-CP diets supplemented with industrial amino acids by favoring a higher DL and NE intakes, possibly due to the lower thermogenic effect of these type of diets. It also must be considered that the greater ADG of pigs fed the diets containing 155g kg -1 CP and 2566kcal kg -1 NE (Exp.…”

“…Similarly, VIDAL et al (2010) Ciência Rural, v.44, n.9, set, 2014. reduced 45g kg -1 CP in the diet for 70-to 100-kg pigs without any variation on ADFI. In a more recent study, MOURA et al (2011) evaluated NE in diets for fi nishing gilts (60-to 92-kg) and also verifi ed no effect on ADFI.…”

“…REZENDE et al (2006) evaluating levels of energy for fi nishing barrows with energy concentrations been obtained by including soybean oil in the diets which probably contributed to increase dietary NE content (NOBLET & SHI, 1994), also found no effect on carcass traits. More recently, MOURA et al (2011), investigating the effects of increased NE levels (2300 to 2668kcal kg -1 ) in diets for fi nishing gilts observed no differences on lean meat percentage and carcass yield. PAIANO et --------------------------CP (g kg -1 ) and NE (kcal kg -1 ), al.…”

Net energy for 60 to 120 kg pigs fed low crude protein diets

“…Similarly, VIDAL et al (2010) Ciência Rural, v.44, n.9, set, 2014. reduced 45g kg -1 CP in the diet for 70-to 100-kg pigs without any variation on ADFI. In a more recent study, MOURA et al (2011) evaluated NE in diets for fi nishing gilts (60-to 92-kg) and also verifi ed no effect on ADFI.…”

“…REZENDE et al (2006) evaluating levels of energy for fi nishing barrows with energy concentrations been obtained by including soybean oil in the diets which probably contributed to increase dietary NE content (NOBLET & SHI, 1994), also found no effect on carcass traits. More recently, MOURA et al (2011), investigating the effects of increased NE levels (2300 to 2668kcal kg -1 ) in diets for fi nishing gilts observed no differences on lean meat percentage and carcass yield. PAIANO et - al.…”