Hy-Line W36 hens were fed diets containing zero or 6% corn oil (CO) from 26 to 38 wk of age. At 38 wk, the hens receiving the diet with 6% CO were divided into three groups. One group continued to receive the diet with 6% CO. The level of CO in the diet was reduced to zero or 3% in the other two groups. The hens previously fed the diet without CO continued to receive the control diet. Egg weight was significantly heavier when the diet contained 6% CO and was not significantly reduced when the level of CO was reduced to 3%. Egg weight from control hens was significantly lower than the EW from hens that had received CO in the diet until 38 wk but none thereafter. Hens fed the diet with CO consumed more energy than hens fed the control diet. However, when CO level was reduced to zero at 38 wk, the hens consumed less energy than hens fed the control diet. These findings indicate that the hen cannot adjust feed intake with diets based on changing energy concentration in the range from 2,783 to 3,089 kcal/kg.

Trezentas e vinte poedeiras comerciais Hy-Line W36<FONT FACE=Symbol>Ò</FONT> com 39 semanas de idade foram utilizadas com o objetivo de determinar a seqüência e o tempo necessário para as galinhas recuperarem as características de desempenho após um período de oito semanas de alimentação, com dietas contendo diferentes níveis de treonina. Oito dietas experimentais, com níveis de treonina variando de 0,35 a 0,53%, foram distribuídas ao acaso, com oito repetições de cinco aves cada. Após esse prévio experimento, as aves foram alimentadas com a dieta controle (0,53% Thr) por quatro semanas em que as características: consumo de ração (CR), de energia (CE), produção de ovos (PO), peso de ovos (PE), massa de ovos (MO) e peso corporal (PC) foram avaliadas. Todas as características foram prejudicadas com dietas deficientes em Thr, e a seqüência da recuperação ocorreu na seguinte ordem: CR e CE; PO, PE e MO e, por último, PC, nos prazos de duas, três e quatro semanas, respectivamente. Os dados obtidos indicaram que uma deficiência em aminoácidos não causa um dano permanente ao sistema reprodutivo das galinhas.

Three hundred and twenty Hy-Line W36<FONT FACE=Symbol>Ò</FONT> commercial laying hens, 39 weeks of age, were used to determine the sequence and the length of time needed for hens to recover performance characteristics after an eight-week period under graded levels of threonine deficiency. Eight experimental diets with Thr levels ranging from 0.35 to 0.53% were randomly fed with eight replicates of five hens each. After the previous experiment, the hens were fed a control diet (0.53% Thr) for a four-week period. Feed consumption (FC), energy intake (EI), egg production (EP), egg weight (EW), egg mass (EM), and body weight (BW) were evaluated. All performance characteristics were impaired on Thr deficient diets. The recovery sequence order was FC and EI; EP, EW and EM, and finally BW, with the length of time of two, three, and four weeks, respectively. The data indicated that an amino acid deficiency does not cause permanent damage to the reproductive system of the hens.