ABSTRACT The objective with this study was to evaluate the effect of including dried distillers grains with solubles (DDGS) as a replacement for soybean meal on feed intake, digestibility, and total digestible nutrients (TDN), as well as plasmatic glucose and serum urea concentrations. Fifteen Saanen goats were distributed in a completely randomized design with three treatments and five replicates. Treatments were soybean meal (SBM), SBM+DDGS (12.28% of dry matter [DM]), and DDGS (23.16% of DM), as protein source in diets, common to all corn ground and mineral-vitamin supplement, and corn silage (60% of DM). Response variables were evaluated every 30 d, from 1 to 120 d after parturition. Measurements included body weight, DM intake, DM and nutrient digestibility, and blood samples. Indigestible neutral detergent fiber was used to estimate fecal excretion. There was a difference in neutral detergent fiber intake from 1 to 30 d after parturition. In the four phases of lactation evaluated, there were treatment effects on DM, organic matter, ether extract, and total carbohydrate digestibility, as well as on TDN concentration. Neutral detergent fiber digestibility was affected by treatments, except from d 61 to 90. There was no treatment effect on non-fibrous carbohydrate digestibility, regardless of period. Therefore, SBM+DDGS (12.28% of DM), as protein source on diets may be used in Saanen goat diets from 1 to 120 d of lactation without negative effects on feed intake, digestibility, and plasma glucose and urea concentrations.

RESUMO Objetivou-se com este estudo avaliar os parâmetros da cinética de degradação ruminal dos concentrados protéicos, farelo de soja(FS) e torta de algodão(TA). Para estimativa dos parâmetros da cinética de degradação in situ da matéria seca (MS) e proteína bruta (PB) dos concentrados, foi realizado o ajuste de 5 diferentes modelos matemáticos não-lineares: Exponencial, Van Milgen, Logístico, Gompertz e Richards. Para avaliação in situ dos alimentos, foram utilizados dois bovinos adultoscanuladosno rúmen. As amostras foram incubadas nos tempos 0; 2; 4; 6; 12; 16; 24; 36; 48 e 72 horas, nos resíduos de incubação foram determinados os teores de MS e PB, e sua degradabilidade potencial e efetiva. Os valores de degradabilidade efetiva da MS do FS foram de 86,35; 74,23 e 65,50%,e da TA de 53,44; 41,70 e 35,21% nas taxas de passagem de 0,02; 0,05 e 0,08.h-1, respectivamente. O FS e a TA apresentaram valores para a fração A da PB de 18,15 e 34,77% e para a fração B, 79,76 e 55,10%, respectivamente. De acordo com a ponderação de Akaike (Wi) o modelo de Richards apresenta; 95,45 e 49,64% de chance de ser o modelo mais adequado, para caracterizar a cinética de degradação in situ da MS do, FS e da TA, respectivamente. Contudo, o modelo de Gompertz apresenta 63,86 e 66,49 % de chance de ser o modelo mais adequado para caracterizar a degradação da PB do FS e TA.

SUMMARY This studied aimed to evaluate the parameters of ruminal degradation kinetics of protein concentrates, soybean meal (SM) and cotton cake (CC).To estimate the in situ degradation parameters of DM and CP from coproducts were fitted 5different non-linear mathematical models: Exponencial, Van Milgen, Logístico, Gompertz and Richards. For in situ evaluation were used two cattle cannulated in the rumen. The samples were incubate dat 0, 2, 4, 6, 12, 16, 24, 36, 48 and 72 hours and in the incubation residues were determined DM and CP and their degradability. The DM degradability of SM were 86.35, 74.23, 65.50% and to CC were 53.44, 41.70 and 35.21% in passage rates of 0.02; 0.05 and 0.08.h-1, respectively. The SM and CC showed values for the CP soluble fraction of the 18.15, 34.77% and 79.76, 55.10% to insoluble potentially degradable fraction, respectively. According to the Akaike weights (Wi) the model of Richards has 95.45 and 49.64% of chance to be the most suitable model to characterize the in situ DM degradation of SM and CC. However, the Gompertz model has 63.86 and 66.49% chance to be the most suitable model to characterize the CP in situ degradation of SM and CC.