RESUMO: Objetivou-se avaliar o melhor valor de balanço eletrolítico total (BET) para as variáveis de desempenho e qualidade dos ovos de galinhas poedeiras. Foram utilizadas 240 galinhas poedeiras da linhagem HyLine Brown, durante o período de 30 a 46 semanas de idade, distribuídos em um delineamento inteiramente casualizado, com cinco tratamentos (1000, 1250, 1500, 1750 e 2000 μeq/kg), oito repetições e seis aves por unidade experimental. Foram avaliados o desempenho e a qualidade dos ovos das aves com os diferentes tratamentos. Foi realizada análise de variância e, no caso de efeito significativo, foram estimadas equações de regressão considerando como variável concomitante o balanço eletrolítico (μeq/kg), usando o programa estatístico SAS (2001). As variáveis de consumo, produção, conversão alimentar por dúzia de ovos, peso final das aves, densidade do ovo, coloração da gema, Unidade Haugh, peso do albúmen, peso da casca e peso do ovo, não foram afetados pelos BET experimentais. Os valores de conversão alimentar por massa de ovos, peso de gema e uniformidade foram influenciados pelos diferentes BET. Os valores de balanço eletrolítico que propiciaram conversão alimentar mínima, melhor peso de gema e melhor uniformidade foram, respectivamente: BET=1400, BET = 1330 e BET = 1250 em μeq/kg de cargas nas rações. Conforme as equações de regressão indica-se o valor de BET de 1390 para poedeiras de 30 a 46 semanas de idade. O balanço eletrolítico da dieta afeta o desempenho e a qualidade dos ovos de galinhas poedeiras.

ABSTRACT: This study was done to determine the best value of the total electrolyte balance (BET) concerning the variables of performance and egg quality of the laying hens. We investigated 240 Hy-Line Brown laying hens, of 30 to 46 weeks of age, adopting the completely randomized experimental design, which included five treatments (1000, 1250, 1500, 1750 and 2000 μeq / kg), 8 repetitions and 6 birds per unit. The performance and quality of the birds’ eggs were evaluated in the different treatments. The results were subjected to the analysis of variance and, wherever significant effect was noted, the regression equations were estimated, taking into account the electrolyte balance (μeq / kg) as a concomitant variable, applying the SAS statistical program (2001). The consumption, production, and feed conversion variables by dozen eggs, final bird weight, egg density, yolk color, Haugh Unit, albumen weight, shell weight, and egg weight, were found to be unaffected by the experimental BET values. The values of the feed conversion per egg mass, yolk weight and uniformity were affected by the different BETs. The electrolyte balance values showing minimum feed conversion, higher yolk weight, and better uniformity were, respectively, BET = 1400, 1330, and 1250 in μeq / kg of loads at the different temperatures. From the regression equations, the value indicated was BET=1390 for the 30- to 46-week-old laying hens. The electrolyte balance of the diet was found to affect the laying hens in terms of performance and egg quality.

The assay was carried out to determine the effect of phytase supplementation on performance of broilers from 1 to 21 and 1 to 40 days of age. Twelve hundred and fifty male broilers (Ross) were distributed in a randomized experimental design, with five treatments, 10 repetitions and 25 birds per experimental unit. The treatments consisted of evaluating the phytase supplementation in diets with reductions in nutritional levels, compared with the positive control. The nutrient contents in negative controls one and two were reduced progressively and these diets were supplemented with phytase levels of 250 and 500 ftu/kg of the diet, respectively. Two diets were formulated: pre-starter/starter, 1-21 days, and growth/finishing, from 21 to 40 days). In both phases, with the phytase supplementation in diets that had their nutritional levels reduced (negative control one + 250 ftu and negative control two + 500 ftu), feed intake, weight gain and feed conversion of the birds were similar to the positive control. In the period from 1 to 40 days of age, with the diets supplemented with phytase, the productive efficiency index of the birds was similar to that of the positive control group. Supplementation with 250 ftu/kg and 500 ftu/kg phytase in diets with reduced nutritional levels improved broiler performance, resulting in parameters similar to those shown by broilers fed with the diet with normal levels of nutrients.

Avaliou-se o efeito dos níveis de treonina digestível, com base no conceito de proteína ideal, em rações com 1,35% de lisina digestível sobre o desempenho de alevinos de tilápia-do-nilo (Oreochromis niloticus). Utilizaram-se 432 alevinos revertidos de tilápia, linhagem tailandesa, com peso inicial de 1,64 ± 0,03 g, em delineamento inteiramente ao acaso, com seis tratamentos, cada um com seis repetições, e doze peixes por unidade experimental. Os tratamentos consistiram de cinco rações com diversas relações treonina:lisina digestível (69,0; 74,0; 79,0; 84,0 e 89,0%) e relação metionina + cistina:lisina digestível de 70,0% e uma ração com relação treonina:lisina digestível de 84,0% e de metionina + cistina:lisina digestível de 75,0%, todas isoenergéticas e isoprotéicas. Os peixes foram mantidos em 36 aquários de 130 L, dotados de abastecimento de água, temperatura controlada e aeração individuais, e alimentados à vontade, seis vezes ao dia, durante 30 dias. Avaliaram-se o desempenho, a composição corporal, as deposições de proteína e gordura e a eficiência de retenção de nitrogênio dos peixes. O consumo de ração, o teor de proteína corporal e a deposição de proteína corporal aumentaram de forma linear de acordo com a relação treonina:lisina na ração, contudo, não foram influenciados pelo aumento da relação metionina + cistina:lisina da ração. Os níveis de treonina total ou digestível que proporcionaram os melhores resultados de desempenho em alevinos de tilápia-do-nilo foram de 1,11 e 0,99%, enquanto os níveis que promoveram melhor deposição de proteína corporal foram de 1,43 e 1,28%, que correspondem às relações treonina:lisina total de 71,0 e 69,0% e treonina:lisina digestível de 90,0 e 89,0%.

The effects of digestible threonine levels, based on ideal protein concept in diets with 1.35% of digestible lysine on Nile tilapia (Oreochromis niloticus) fingerlings performance. Four hundred thirty two reverted Nile tilapia, Thailand strain, with initial weight of 1.64 ± 0.03 g, were allotted to completely randomized design, with six diets and six replications with twelve fishes each. The five diets, isoenergetic isoproteic, consisted of various threonine:digestible lysine ratio (69.0, 74.0, 79.0, 84.0, and 89.0%) and methionine + cystine:digestible lysine ratio of 70.0% and one diet with threonine:digestible lysine of 84.0% and methionine + cystine:digestible lysine of 75.0%. The fish were kept in 36 aquariums of 130 L, equipped with water supply, controlled temperature and individual aeration, and ad libitum fed six times a day for 30 days. Performance, body composition, protein and fat depositions and nitrogen retention efficiency of fishes were evaluated. Consumption of feed, body protein content and body protein deposition increased in a linear fashion in accordance to threonine:digestible lysine in the diet, however, was not affected by the increase of dietary methionine + cystine:digestible lysine. Total or digestible threonine levels that provided the best results of performance of Nile tilapia fingerlings were 1.11 and 0.99%, while the levels that promoted better body protein deposition were 1.43 and 1.28%, which correspond to threonine:total lysine ratio of 71.0 and 69.0% and threonine:digestible lysine of 90.0 and 89.0%.