## 1 Introduction  
In Italy, milk from water buffaloes (_Bublus bublis_, Mediterranean type) is produced in specific areas of Lazio and Campania Regions. In recent decades, buffalo farming has been involved in an intensification of rearing and feeding techniques, so that total mixed ratios (TMR) based on silages, hays, and concentrates are commonly used throughout the year, with limited or no use of fresh forage or pasture. This feeding system, made necessary also by the limited farm size, allows increasing both productions of milk/cow and the number of animals raised on farm, and ultimately the farm income. Buffalo milk is almost completely transformed in mozzarella, a fresh cheese covered by the EU Protected Denomination of Origin (PDO) \"Mozzarella di Bufala Campana\" (Commission Regulation EC No 103/2008) [1; 2; 3]. This cheese presents peculiar sensory properties and flavor, playing an important role for the product specificity and consumer acceptability, also in relationship to volatile organic compounds (VOCs) arising from raw buffalo milk and cheese-making technology. The odor of raw buffalo milk is indeed very different from other ruminants' milk, due to specific VOC profiles, being 1-octen-3-one, nonanal, indole, 3-hydroxy-2-butanone, 3-methyl-2-buten-1-ol, 2-octanone, 2-hydroxy-3-pentanone, and heptanal, the main buffalo milk odor-active VOCs [4; 5; 6]. Native milk VOCs arise mainly from the animal diet, some of them already present in the feeds, others transformed during the digestion, absorbed, and directly transferred into milk via rumen and/or via the respiratory tract [7; 8; 9; 10]. The mozzarella cheese flavor instead arises mainly from the interaction among native milk components, microbial starters, rennet, cheese making technology, and secondary microflora enzymes [5].  
It is well known that the inclusion of fresh forage in ruminants' diet may produce healthier milk, since it is richer in conjugated linoleic acid and n-3 fatty acids [11; 12], and might also increase the casein and protein content, an issue of importance for mozzarella yield [13]. In this regard, the increased consumer interests about the nutritional and health properties of foods and their contribution to the human diet could create new market opportunities for mozzarella cheese [14]. The variations in milk composition induced by the cow feeding can be reflected in milk and cheese flavor, according to the metabolic pathways involved in aroma compound production [15]. Although a certain number of studies examined how the forage type can affect VOCs and organoleptic properties of cow milk and cheese [16; 17; 18; 19; 20; 21; 22], to the best of our knowledge, only one study has examined this topic for buffalo dairy products, finding that, compared to hay, the use of ensiled forage significantly increased the decanal and nonanal, alcohols, ketones, and terpenes of mozzarella cheese [23].  
The hypothesis of this study is that the inclusion of fresh-cut forage in a TMR for lactating buffalo under ordinary farming conditions may also influence, beside the fatty acid composition, the VOC profile of milk and cheese. We used sorghum, a forage species that is spreading in intensive Italian dairy farming, since, compared with maize silage, it is more flexible (it can be used both fresh and ensiled), and needs lower inputs of water and nitrogen fertilizer [24; 25]. Therefore, following up on a previous study describing the effect of the use of fresh forage on mozzarella fatty acid composition and sensory properties [26], this paper aimed to examine the VOC composition of buffalo raw milk and mozzarella produced by including 20 kg of fresh sorghum in the diet for lactating buffaloes.