Influences of dietary protein level, amino acid supplementation and environmental temperature on performance, body composition, organ weights and total heat production of growing pigs1

Abstract

The study was conducted to determine the effects of feeding a 16% CP diet, a 12% CP diet, or a 12% CP diet supplemented with crystalline Lys, Trp, and Thr (12% CP + AA diet) in a thermal-neutral (23 degrees C) or heat-stressed (33 degrees C) environment on various body and physiological measurements in growing pigs. Heat-stressed pigs were given a 15% lower daily feed allowance than thermal-neutral pigs to remove the confounding effect of feed intake caused by high temperature. No diet x temperature interaction was observed for any variables (P > 0.09) except for pig activity and pancreas weight. At 33 degrees C, pig activity and pancreas weight did not differ among dietary treatments (P > 0.05). In contrast, at 23 degrees C, pigs fed the 12% CP diet had greater activity than those fed the 16% CP diet or the 12% CP + AA diet (P < 0.05). Pancreas weight was greater for pigs fed the 12% CP + AA diet than those fed the 12% CP diet (P < 0.05) when maintained at 23 degrees C. Compared with 23 degrees C, the 33 degrees C temperature decreased pig activity, heat production, daily gain, feed efficiency, and affected the concentration and accretion of empty body protein and ash, as well as weights of heart, pancreas, stomach, and large intestine (P < 0.05). Pigs fed the 12% CP + AA diet attained similar levels of performance and rates of empty body water, protein, lipid, and ash deposition as pigs fed the 16% CP diet (P > 0.10). Pigs fed the 12% CP + AA diet had lower serum urea plus ammonia nitrogen concentrations (P < 0.01) and total heat production (P < 0.05) compared with those fed the 16% CP diet or the 12% CP diet. These results confirm that, with crystalline AA supplementation, growing pigs fed a 12% CP diet will perform similar to pigs fed a 16% CP diet. The data further indicate that lowering dietary CP and supplementing crystalline AA will decrease total heat production in growing pigs whether they are housed in a thermal-neutral or heat-stressed environment.

Efeitos da temperatura ambiente sobre o desempenho de suínos dos 30 aos 60 kg

“…Os similares (P>0,05) valores de deposição de proteína (DP) verificados nos animais mantidos sob calor e conforto térmico recebendo alimentação à vontade diferem do observado por Kerr et al (2003). Esses autores registraram, em suínos em crescimento mantidos a 25 e 33 o C com alimentação à vontade, menor concentração de proteína corporal que naqueles sob temperatura mais elevada.…”

“…Os pesos relativos do fígado, dos rins e do intestino delgado foram semelhantes aos obtidos por Kerr et al (2003), em suínos em crescimento.…”

“…Quando submetidos, porém, a ambientes de alta temperatura, os suínos tendem a perder a eficiência de utilização da energia disponível à medida que acionam mecanismos de termorregulação para redução do impacto do ambiente quente sobre seu organismo (Kerr et al, 2003).…”

Effects of low-protein diets supplemented with indispensable amino acids on growth performance, intestinal morphology and immunological parameters in 13 to 35 kg pigs

“…It is well documented that reducing dietary CP level from 16% to 12%, supplemented with indispensable amino acids (IAA), could maintain similar growth performance as pigs fed control diet (Figueroa et al, 2002 andKerr et al, 2003). In addition, a moderate reduction of dietary CP level has been shown to decrease the harmful microbial metabolites in the digesta such as ammonia N (Nyachoti et al, 2006;Opapeju et al, 2008), as well as improving the villous morphology of weaned piglets (Gu and Li, 2004;Opapeju et al, 2008).…”

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

“…Tem-se constatado que além de aumentar a deposição protéica, a ractopamina inibe parcialmente a lipogênese, reduzindo a deposição de gordura na carcaça (PÉREZ et al, 2006). Todavia, quando os suínos são submetidos a ambientes de alta temperatura, tendem a reduzir o consumo e perder a eficiência de utilização da energia disponível, à medida que acionam mecanismos de termoregulação para manter a homeostase térmica (KERR et al, 2003). Nas circunstâncias em que as temperaturas ambientais são elevadas e o consumo dos animais é reduzido, a inclusão de lipídios às dietas pode reduzir o incremento calórico e minimizar a redução do desempenho devido ao baixo consumo (ALMEIDA et al, 2007).…”