ABSTRACT. The objective of this study was to evaluate the behavior of carbon incorporation and turnover in hoof and ribs of pigs at different periods of development in the search for tissues that reflect longer the former diet. We used 132 commercial hybrids (barrows and females), weaned at an average age of 21 days, distributed in a completely randomized design with four treatments on different days of substitution of corn (C4 cycle plant grain) diets with broken rice (C3 cycle plant grain) at 21, 42, 63 and 110 days of age to change the carbon-13 isotope signal. By means of isotopic dilution curves, we observed that animals whose C4 diet was replaced with C3 diet at 21, 42, 63 and 110 days of age, for hoof and rib, reached a new level of isotope equilibrium. Bone samples are better choices to reflect the former diet, due to conservation of the isotopic signal for longer.

Foi realizado um experimento objetivando avaliar o melhor nível de substituição da lactose por maltodextrina em dietas de leitões desmamados. Utilizaram-se 120 leitões, distribuídos em delineamento experimental de blocos ao acaso, formando fatorial 2 x 4 (duas dietas: simples e complexa e quatro níveis de maltodextrina substituindo a lactose: 0,0; 33,5; 66,5 e 100%). Avaliou-se o consumo diário de ração (CDR), ganho diário de peso (GDP) e conversão alimentar (CA). Não houve interação entre os níveis de maltodextrina e as dietas. Leitões que consumiram as dietas complexas apresentaram maior GDP no período de 0 a 15 dias pós-desmame, melhor CA nos períodos de 0 a 15 dias e 0 a 30 dias (p < 0,05). Não foram observados efeitos (p > 0,05) dos níveis de maltodextrina em relação ao CDR, GDP nos dois períodos e na CA para o período de 0 a 15 dias. O aumento do nível de maltodextrina na dieta acarretou efeito quadrático para CA (p = 0,006, Ŷ = 1,53 + 0,002287X + 0,000022X²) no período de 0 a 30 dias. As dietas contendo somente maltodextrina na composição proporcionaram menor custo de ração. A maltodextrina pode substituir totalmente a lactose nas dietas, sem afetar o desempenho de leitões desmamados aos 21 dias.

The goal of this experiment was to find the best level of substitution of maltodextrin for lactose for pre-starter and starter rations, whether simple or complex, fed to piglets weaned at 21 days. One hundred and twenty piglets were used in a randomized block design, according to a 2 x 4 factorial (two diet types: simple or complex; and four levels of maltodextrin as a replacement for lactose: 0.0, 33.5, 66.5 and 100%). The daily feed intake (DFI), daily weight gain (DWG) and feed conversion (FC) were measured. No interaction between maltodextrin levels and diet type was observed. The piglets fed the complex diets showed higher DWG from 0 to 15 days post-weaning; better FC. No effect of maltodextrin levels on DWG and DFI was observed from 0 to 15 days or from 0 to 30 days; and FC from 0 to 15 days. Maltodextrin showed a quadratic effect (p = 0.006, Ŷ = 1.53 + 0.002287X + 0.000022X²) on FC from 0 to 30 days. Diets containing only maltodextrin in it composition provided the lowest cost of feed. The maltodextrin can fully replace lactose in diets, not affecting the performance of piglets weaned at 21 days.

One hundred and twenty six piglets from a commercial genetic strain weaned at 21 days of age (6.11±0.42 kg) were used to evaluate the effects of supplementation levels of organic sources of trace minerals in the diets of weaned piglets on performance, occurrence of diarrhea, excretion of copper and zinc in the feces, and hematological parameters. A completely randomized block design was adopted, composed of six treatments (diets containing 100% of inorganic trace minerals premix at 3.00 kg/T; diets containing 0, 25, 50, 75 or 100% of organic trace minerals premix, equivalent to 0; 0.75; 1.50; 2.25 or 3.00 kg/T, respectively), seven replicates and three animals per plot. During the experimental period (from 21 to 63 days of age), the increasing levels of organic trace minerals premix in the diets determined a quadratic effect on daily weight gain (DWG), feed conversion (FC), percentage of hematocrit (Ht), hemoglobin (Hb), mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), platelets (Pt), and a linear increase of Cu and Zn concentrations in feces. The comparison of means between the treatment with inorganic trace minerals premix and the other treatments showed that piglets fed diets without trace minerals premix had lower values of DWG, Ht, Hb, MCH, MCV, Pt and the worst FC value of piglets fed diets containing 25% of organic trace minerals premix presented lower values of Ht and Hb, in comparison with those fed diets with 100% of inorganic trace minerals premix. Inorganic trace minerals premix can be substituted by organic trace minerals premix at a lower level of inclusion in diets for weaned piglets.