Effect of feeding increasing levels of spent coffee grounds on milk yield and composition, methane emissions, milk fatty acid profile and curd sensory characteristics in Latxa dairy sheep

Abstract

This study aimed to evaluate the effect of increasing levels of spent coffee grounds (SCG) in the concentrate on milk yield and composition, methane emissions, milk fatty acid (FA) profile and curd sensory properties in Latxa dairy ewes. In this 7-wk trial, forty-eight Latxa ewes were grouped into quartets based on milk yield and days in milk. Within each quartet, ewes were randomly assigned to one of four treatments corresponding to the inclusion level of SCG in the concentrate: Control (0 g/kg DM), SCG100 (100 g/kg DM), SCG150 (150 g/kg DM) and SCG200 (200 g/kg DM). All concentrates were formulated to be isoenergetic, isoproteic and isofat to meet the production requirements of the ewes. The concentrate was provided individually in two equal portions of 450 g DM per milking, while vetch-oat silage was offered ad libitum in group feeders. Ewes were milked daily at 0730 and 1800 h, and individual milk yield was recorded electronically. Milk samples were collected on days 30, 37 and 44 for composition analysis and on days 43 to 46 for the determination of milk FA composition. Enteric methane emissions were individually measured using a nondispersive infrared gas analyzer on days 21, 23, 28, 30, 35, 37, 42 and 44 of the trial. Increasing the level of SCG inclusion in the concentrate up to 200 g/kg DM resulted in a linear reduction in daily CH4 emissions (P = 0.025) and CH4 intensity (P = 0.001), along with a change in the milk FA profile, decreasing total saturated FA (P = 0.005) and increasing total monounsaturated and polyunsaturated FA (P = 0.019 and P < 0.001, respectively). Moreover, this was associated with no detrimental effect on daily milk production or on the protein and fat composition of milk. The sensory acceptability of the curd remained unaffected by the inclusion of SCG at 200 g/kg DM in the concentrate. In conclusion, including SCG at levels up to 200 g/kg DM in the concentrate of dairy ewes reduces CH4 emissions and intensity, improves the milk's FA profile toward a healthier composition, without negatively affecting the ewes' milk production or the sensory acceptability of the curds. Lay Summary Reducing the environmental footprint associated with food waste and livestock enteric CH4 emissions is critical to achieving environmental sustainability. Spent coffee grounds (SCG), a major by-product of coffee beverage preparation, represent a significant source of food waste worldwide. Due to its fiber and polyphenol content, SCG has attracted growing interest as a functional feed ingredient in ruminant nutrition. This study investigated the effects of including increasing levels of SCG in the concentrate of dairy sheep. Forty-eight Latxa dairy ewes were assigned to one of four treatments: Control (0 g/kg DM), SCG100 (100 g/kg DM), SCG150 (150 g/kg DM) and SCG200 (200 g/kg DM). Results showed that including up to 200 g/kg DM SCG in the concentrate reduced enteric CH4 emissions and improved the milk fatty acid profile, without affecting milk production and composition, or sensory quality of the curd.