Aiming to determine the ration between digestible lysine and digestible threonine (Thr/Lys) for weaned piglets at 27 days, kept in the nursery under sanitary challenge conditions, 105 hybrid piglets with initial weight of 7.2 ± 0.41 kg, were distributed in randomized block design inside of five treatments (Thr/Lys ratios of 0.56; 0.63; 0.70; 0.77 and 0.84), seven replicates and three piglets per experimental unit. The Thr/Lys ratios did not affect (P>0.05) piglet performance. There was quadratic effect (P=0.02) of the Thr/Lys ratio on the protein/fat ratio and the estimated point of the bigger protein/fat ratio occurred with the Thr/Lys ratio of 0.68. The Thr/Lys ratio did not affect (P>0.05) the carcass parameters and serum urea levels, however, the liver and kidney weights raised with the increase (P=0.01) in Thr/Lys rate. The Thr/Lys ratio had a quadratic effect (P=0.01) on rate of plasma haptoglobin, Thr/Lys ratio was estimated at 0.74. It was concluded that the ratio between digestible threonine with digestible lysine for piglets from 27 to 48 days of age raised under sanitary challenge conditions is 0.74.

This study was conducted to determine the metabolizable energy (ME) requirement for quails (Cortunix cortunix cortunix) from 28 to 42 days of age. Four hundred and twenty quails were distributed in a completely randomized design, with 5 treatments (2950, 3000, 3050, 3100 and 3150 kcal of ME/kg of feed), 7 replicates and 12 birds per experimental unit. Performance, relative weights of organs and viscera, carcass characteristics, meat quality, body composition and blood parameters of the birds were evaluated. There was a reduction in feed intake (ADFI) with the use of 3150 kcal ME/kg (p < 0.01), with a quadratic effect on feed efficiency (p < 0.01), estimating the energy requirement in the 3009.4 kcal ME/kg. The breast yield (BY) and the colour b* had an effect (p < 0.01), with better results for 2950 kcal ME/kg, while the meat texture reduced when the birds were fed with 3150 kcal ME/kg. HDL and LDL showed the quadratic effect (p < 0.01) when ME increased to 3111.6 and 3157.4 kcal/kg respectively. Very low density lipoprotein increased linearly (p < 0.01) in birds that received diets with 3000 kcal ME/kg. We conclude that the use of 3009.4 kcal of ME/kg for European quail meets the nutritional needs and provides an improvement in feed efficiency, without affecting the carcass parameters of the birds. Information regarding the nutritional requirements for European quails is still recent; therefore, it is essential to know the adequate levels of metabolizable energy, an important nutritional component for the maximum productive performance of birds.