Effects of dietary sucrose levels on the ingestive behavior, blood parameters, and performance of feedlot lambs

The addition of sucrose to the diet may accelerate rumen development and improve the utilization of dietary protein, thus increasing lamb performance. This study aimed to evaluate the effects of four dietary sucrose levels on the ingestive behavior, blood parameters, and performance of crossbred Dorper lambs fed on feedlot. Twenty-four non-castrated male lambs with a mean age of 4 months and a body weight (BW) of 26.06 +/- 0.77 kg were allocated to individual pens. The trial was accomplished in a completely randomized design with four treatments and six replicates, and the treatments were a diet without sucrose (control) and the inclusion of 15, 30, and 45 g/kg of sucrose in the concentrate feed, on a dry matter (DM) basis. The diets were composed of 400 g/kg DM of Tifton 85 hay (Cynodon spp.) and 600 g/kg DM of pelleted concentrate feed, and contained 177 g/kg DM of crude protein (CP) and 2.75 Mcal/kg DM of digestible energy (DE), on average. The diets were supplied as total mixed ration, and the lambs were fed ad libitum for 56 days. The time spent in rumination increased linearly, whereas the time in idleness decreased linearly with addition of sucrose up to 45 g/kg DM of concentrate. The time spent feeding and on water intake were not affected by sucrose levels. The proportion of particles larger than 7.8 mm and smaller than 19 mm of orts showed a quadratic response to sucrose levels, indicating an influence of this sugar on the selective behavior of lambs during feeding. The pH of rumen fluid and the papillae height in the rumen epithelium were not influenced by sucrose levels, nor were blood metabolites. Neutral detergent fiber intake increased linearly with addition of sucrose up to 45 g/kg DM of concentrate, whereas the performance and feed efficiency traits were not affected by sucrose levels, nor were CP and DE intake. Addition of sucrose up to 45 g/kg DM of concentrate feed reduces the palatability of the diet, leading the lambs to partially reject the concentrate and increase their fiber intake from hay. Under this condition, rumination activity is intensified, but rumen pH and papillae height of the rumen epithelium, the blood biochemical profile, performance, and feed efficiency are not affected.

Automated summary

The addition of sucrose up to 45 g/kg DM of concentrate feed affects the ingestive behavior of crossbred Dorper lambs, but does not significantly impact various parameters and performance.