Interactive effects between sugar source and pelleting temperature on processing, digestibility and blood metabolites in nursery piglets

Abstract

The aim of this study was to evaluate the effect of pelleting temperature (60°C or 90°C) and the type of sugar source (refined sugar cane or sugar cane molasses), on post-processed diet characteristics and on animal body weight gain, apparent total tract digestibility of energy and nutrient, and blood metabolites. Thirty-two recently-weaned piglets of both sexes were randomly assigned to 1 of the 4 treatments in a 2 (sugar source, refined sugar cane or sugar cane molasses) x 2 (pelleting temperature, 60°C or 90°C) factorial arrangement. The physicochemical characteristics of the diets evaluated were pellet durability index, fine content and starch gelatinization index. After seven days of adaptation, partial fecal samples were collected for apparent digestibility analyses for five days. For weight gain evaluation, the animals were weighed at 28, 35, 40 and 63 days of age. Blood samples were collected at the beginning (28 days) and the end of the experiment (63 days). Data were submitted to variance analysis and the means were compared by the Tukey test. There was interaction between pelleting temperature and sugar source on the pellet durability index, on the fine content and on the starch gelatinization index (P < 0.05) of the diets. Pelletizing at 90°C increased the pellet durability index in treatment with sugar cane molasses. The fine content was reduced in treatments with pelleting temperature at 90°C and increased in treatments with sugar cane molasses. There was an increase of the starch gelatinization index with refined sugar cane at 90°C. There was no interaction between pelleting temperature and sugar source on starch composition of the diets. The pelleting temperature and the type of sugar source did not influence the levels of resistant and non-resistant starch (P > 0.05). The total starch index was higher in treatments using sugar cane molasses. There was no interaction between pelleting temperature and sugar source on nutrient apparent total tract digestibility. The use of sugar cane molasses promoted higher apparent digestibility of gross energy and ash (A), and pelleting at 90°C increased the apparent digestibility of Ca, P and A (P < 0.05). There was interaction between pelleting temperature and sugar source on the gamma-glutamyltransferase (GGT) enzyme (P < 0.05), where the use of sugar cane molasses reduced GGT levels in the pelleted diet at 60°C. There was no effect of pelleting temperature and the type of sugar source on animal body weight gain, high density cholesterol (HDL), total cholesterol, triglycerides, urea and albumin. Therefore, sugar cane molasses can replace refined sugar cane as the palatable ingredient in the diet of nursery piglets without affecting animal body weight gain and levels of blood metabolites of the animals, promoting greater apparent digestibility of gross energy and ash, although it had altered the physicochemical characteristics of the diet. The use of sugar cane molasses allowed for the exploration of higher pelleting temperatures (90°C) in the feed processing, leading to increasing the apparent digestibility of Ca, P and A of the diets.