Can residual frying oil be an alternative to traditional sources of vegetable oils for sheep diets

Abstract

This research aimed was to evaluate sources of vegetable oils in lamb diets regarding intake, digestibility, ruminal fermentation parameters, and microbial protein synthesis. Twelve mixed-breed, non-castrated lambs (45.00 ± 8 kg of body weight) were used and distributed in a triple 4 × 4 Latin square design. Each experimental period lasted 20 days, with 15 days of animal adaptation to the diets and 5 days of data collection. The evaluated treatments were as follows: a control diet without vegetable oils and diets containing 2% DM from one of the following oil sources: soybean, sunflower, or residual frying. The diets were balanced to be isonitrogenous with a roughage-to-concentrate ratio of 40:60. There was an 11 % reduction in DM intake when comparing the vegetable oil sources to the oil-free diet (1258 g animal-1 day-1). There was effect of the addition of vegetable oils on the digestibility of CP and NDF, where, on average, the oil sources reduced the digestibility by approximately 5 % and 8 %, respectively. Although the time spent on feeding and rumination did not change with the addition of oils, it was reflected in the pH and N-NH3 of ruminal fluid, which also did not show any effect. However, there was an effect on microbial protein synthesis, where diets with soybean oil, sunflower, and frying residue showed greater efficiency and synthesis of microbial protein. Based on the results, it is possible to conclude that vegetable oil sources can be used in diets for growing lambs without causing damage to the ruminal environment or interfering with microbial growth.