Productive, environmental and economic effects of black grape pomace silage in the diet of Murciano-Granadina dairy goat

One of the problems facing the wine production industry is the enormous amount of by-product that is generated in the manufacturing process, since it can, through poor management, constitute serious environmental damage. In 2023, Spain produced 1,398.7 thousand tonnes of winemaking by-product, so this work addresses the study of the productive, environmental and economic effects of its inclusion at different levels in the diet of dairy goats to replace part of the alfalfa hay, as a formula for circular economy and zero waste. Thirty-two Murciano-Granadina breed goats were used in a cage study on the digestibility of four diets containing 0%, 6%, 12% or 18% dry matter of black grape pomace. The results showed that the optimum level of black grape pomace incorporation was 12% dry matter, as compared to the control group, consumption of the diet was not affected, the balance of digestible and metabolisable energies was similar, the milk production and its gross composition was maintained, the level of some polyunsaturated fatty acids in milk tended to improve and the emission of greenhouse gases was reduced. From an economic standpoint, this experiment indicates that this substitution means, compared to the control group, the saving of 340 g of alfalfa hay, although 530 g of fresh black grape pomace silage was needed, all of this per goat per day. So, the interest in its use will depend on the prices of the variables mentioned and on the appreciation of the environmental and health benefits.