The water footprint of Spanish Ternera de Navarra PGI beef: conventional versus novel feeding based on vegetable by-products from the local food industry

CONTEXT: In recent years, livestock farming has been in the spotlight. Meat production is blamed for the pollution of aquifers and rivers, as well as for the large amount of water required to feed livestock. This has highlighted the need to find alternative feeding systems for cattle breeding able to reduce food/feed competition. OBJECTIVE: In this context, the present study compares the water footprint (WF) of conventionally fed beef versus beef fed with vegetable by-products from the local agri-food industry. METHODS: Twenty-four entire male young bulls were reared under the Ternera de Navarra Protected Geographic Identification (PGI) in the town of Azoz, in Navarra, Spain. Twelve calves were fattened on a diet based on vegetable by-products and fodder and grain to complement the ration (VBP diet) and the remaining animals were fattened with a traditional diet based on concentrate and straw (conventional or control diet). RESULTS AND CONCLUSIONS: Once the fattening was finished and animals were slaughtered, the results showed a larger green, blue and grey WF in terms of m3 per beef cattle for conventionally fed animals compared to those fed with VBP. However, when looking at the efficiency, the results were mixed. Conventionally fed cattle exhibited lower green and grey WFs but a higher blue WF compared to VBP-fed cattle, with values of 9955 l/kg, 1577 l/kg and 1731 l/kg versus 10,147 l/kg, 1457 l/kg and 1831 l/kg of carcass beef, respectively. SIGNIFICANCE: This means that a by-product-based calf diet can reduce blue water use. However, further research is needed on the indirect water pollution associated with animal-fed crop production.