Use of sunflower meal as a protein source in diets of growing lambs

This study aimed to evaluate the effects of sunflower meal (SFM) inclusion on the performance, nutrient digestibility, and respirometric parameters in sheep. Twenty-four Dorper x Santa Ines uncastrated males, with an average age of 5 mo and initial body weight (BW) of 27.91 +/- 6.0 kg, were distributed in a randomized block design with four treatment diets containing 0, 100, 200, and 300 g of SFM/kg of total dry matter, replacing soybean meal. Intake, weight gain, ingestive behavior, and in vitro digestibility were evaluated according to the SFM inclusion. The respirometric parameters were evaluated in an open-circuit respirometric chamber. There was a quadratic response in dry matter intake expressed according to the SFM inclusion, with minimum points of 90.56 g/kg(0.75) BW for inclusion levels of 96 g of SFM/kg. A linear decrease in the in vivo digestibility of dry matter, neutral detergent fiber, and non-fibrous carbohydrate and in vitro fermentation of dry matter and fibrous carbohydrates was observed in response to SFM inclusion. These results reflect the higher fiber content of the byproduct, which reduced the non-fibrous carbohydrates in the diets. Despite the change in nutrient availability, average daily gain (299 g/day), O-2 consumption (26.24 L/kg(0.75) BW), and CH4 production (2.25 L/kg(0.75) BW) were not influenced by the SFM inclusion, indicating that changes in the nutritional value of the diet did not affect the animals' energetic metabolism. Sunflower meal inclusion decreased the digestibility but did not affect the animal gain and the respirometric parameters. The SFM can replace soybean meal in the diet of growing lambs; however, it has a maximum inclusion point of 88 g SFM/kg for feed conversion, which is a necessary factor for evaluating the replacement cost.