Buffalo (Bubalus bubalis) farming represents a sector of considerable economic importance in southern Italy, primarily due to its role in the production of mozzarella cheese (1, 2) and, to a lesser extent, for meat (3). Although buffaloes digest fibrous feeds more efficiently than cattle (4), high energy and protein diets are formulated to increase milk yield, with high risk for negative outcomes on ruminal fermentations (5) as undesirable effect. Corn silage is widely used in the diets of lactating buffalo cows, despite requiring intense irrigation, raising concerns from economic and environmental sustainability perspectives (6). In this context, the interest in forages with less environment impact than corn is progressively increasing; particularly, sorghum is attracting attention given the possibility to be used, as forage or grain, especially as replacement of corn when agronomic practices must face water scarcity for irrigation. Indeed, the capacity of sorghum to tolerate periods of water scarcity and to restore vegetative activity when subjected to stress has been demonstrated (7). The partial or complete replacement of corn with alternative forages such as sorghum can also be seen as part of a broader strategy for the environmental, social and economic sustainability of buffalo farming, in line with the Sustainable Development Goals (SDGs) of the United Nations’ 2030 Agenda (8). Specifically, thanks to sorghum adaptability to adverse environmental conditions and its remarkable water use efficiency, it is possible to contribute concretely to achieving SDG 12 (Responsible Consumption and Production) and SDG 13 (Climate Action), significantly reducing water consumption and the ecological footprint of livestock farms. Compared with maize it needs lower inputs of water and nitrogen fertilizer (9, 10). The high-water efficiency of sorghum therefore allows for reduced use of irrigation and energy for water supply, with a positive environmental and economic impact. Moreover, in the current context, marked by increasing price volatility of feed and raw materials, the use of forage crops with low cultivation costs can be one of the strategic levers to contain feed expenses, which represent one of the main cost items in dairy farming. Green fodder sorghum in livestock farming is used by means of the “cut and carry” technique, i.e., harvested when it has reached a height of at least 70–80 cm (not beyond the keg stage). This nutritional strategy involves offering freshly mown sorghum directly in the trough or incorporating it as an ingredient in a total mixed ration (TMR) (Total Mixed Ration) (11, 12). This technique allows to improve milk nutritional characteristics since grass is a profitable source of mineral and vitamins (13). Cut and carry technique has proven to increase productivity in the field, with up to a 25% increase in grass growth rates and a 15% improvement in grass utilization compared to grazing (5). Indeed, by using cut and carry, there is an improvement of land utilization per hectare by 15% and an increase in forage intake (1.6 kg/cow/day) and milk yield, fat and protein compared to grazing (5). Since the latest hybrid fodder varieties contain negligible amounts of dhurrin, the plant can be left to wilt in the field after mowing (only small amounts of hydrocyanic acid are produced), reducing the size of the forage and improving its intake. The hypothesis of this study was that the inclusion of green sorghum in the diet of buffalo cows would have a beneficial effect on the rumen environment, thus improving milk yield and quality. This in turn would have a positive effect on the economic sustainability of buffalo farms. The present trial aimed to evaluate the influence of partially replacing the corn silage with green sorghum in the diet of lactating buffalo cows on milk yield and quality, as well as to estimate the economic sustainability of this feeding system.

The study was approved by the Ethical Committee for Animal Care and Use of the University of Naples Federico II (Prot. 2019/0013729 of 8 February 2019) and was conducted from July to September 2024 at a commercial buffalo farm in the province of Caserta (Campania region, Italy, 123 m asl, 41°18′N 14°15′E, with 638 mm mean rainfall and 15.3–25.5 °C mean temperature). In the experimental period (July–September 2024) the temperatures ranged from 20 to 29.2 °C, humidity was 74.6% and 30 mm of rainfall were estimated.

Sorghum showed higher crude protein and NDF contents when compared to corn silage. Nevertheless, the two diets were isonitrogenous and isoenergetic, although the diet of group S had a slightly lower starch content (Table 2).

No TMR orts were detected, and the DMI and the BCS were not different between the groups. The OM, CP, EE and starch digestibility did not differ between the groups, while the digestibility (%) of NDF and ADF were significantly (p < 0.01) higher in group fed green sorghum (see Table 3).

The mean values of MY, protein and lactose content did not differ between the two groups (Table 4). In contrast, milk fat was significantly (p < 0.01) higher in the group fed with green sorghum. In both groups as lactation progressed, there was a significant (p < 0.05) decrease in milk production and a simultaneous increase in fat and protein levels. Lactose content, on the other hand, did not significantly vary according to the progress of lactation.

No significant differences were detected for milk somatic cell content; on the contrary, the level of milk urea (MUN) was significantly (p < 0.05) lower in group S. Finally, the estimated mozzarella cheese yield (MCY) was higher for the group of buffaloes fed the diet containing green sorghum. It should be noted that this parameter was consistently higher for the S group throughout the trial (Table 5).

The inclusion of green fodder in the diet could result to be economically advantageous for a lower cost impact and higher estimated mozzarella cheese yield. Table 6.

The present study hypothesized that the inclusion of green fodder sorghum in the diet of buffalo cows would enhance milk yield and composition. This in turn would positively impact the economic sustainability of buffalo farms, due to the increased production and to the reduced input cost.

The chemical composition of green fodder sorghum was in line with that reported in the literature (21). However, the CP content was higher, and NDF content was lower, than the values reported by Uzun et al. (22) who observed 7.1% CP and 45.7%, NDF. This discrepancy may be attributed to differences in the physiological stage at harvest, as Uzun et al. (22) evaluated the forage at the milk stage of development, which, as suggested by Oliveira et al. (23), can substantially influence its nutrient composition. In present study NDF and ADF content falls in the range (500–600 g/kg DM and around 300 g/kg DM, for NDF and ADF, respectively) recommended to avoid decrease in the intake rate and to guarantee the activities of rumen microorganisms and enzymes (24, 25). The replacement of corn silage with green fodder sorghum in the diet did not affect protein and energy concentrations, which were adequate for lactating buffalo cows (26). This result agrees with that reported by Neglia et al. (27) in a trial carried out on buffaloes over 110 days of lactation fed diets characterised by higher protein and energy concentrations (16.5% CP and 0.95 UFL/kg DM). Similarly, no alteration in DMI was recorded and in both groups it was in the range reported by others (28, 29) for lactating buffalo cows confirming the good palatability of green fodder sorghum. As a matter of fact, the buffalo species is known to be wary of the introduction of new feed ingredients in their diet (30, 31). The higher digestibility of NDF and ADF of sorghum compared to corn has been reported in buffalo cows, by Tudisco et al. (6) and in dairy cows by Miron et al. (32). The inclusion of green sorghum in the diet did not lead to a decrease in MY, as also reported by Neglia et al. (27), while milk fat content was significantly higher as also reported by Tudisco et al. (6) on buffaloes fed with sorghum silage. This outcome is probability due to the higher digestibility of the fibrous fractions of diet with sorghum, as confirmed by Calabrò et al. (33) in an in vitro trial.

The result concerning milk urea is of particular interest; indeed, the soluble and degradable fractions of diet protein are thought as the main cause of MUN increase (34) because rumen microbes cannot fully capture the excess ammonia (NH₃) when energy support is limited. The surplus NH₃ is therefore absorbed into the bloodstream, converted to urea in the liver, and then excreted in milk and urine. According to Gustafsson et al. (35), fresh forages contain high rumen degradable protein therefore the inclusion of green fodder sorghum in the diet should have result in MUN increase. Instead, Roseler et al. (36) demonstrated that also the contribution of protein by-pass is important in influencing MUN. In fact, these authors fed dairy cows with diets characterized by different ratio of degradable/by-pass protein obtaining similar MUN values. Therefore, other factors (total energy input, fermentable energy input, energy balance fermentable/degradable proteins, rumen nitrogen balance, amino acid composition of the by-pass fraction, lactation stage, productive level) are important as well (37). In the present trial the two diets were isoproteic and isoenergetic; therefore, these two factors would have not be responsible for MUN differences. However, the better utilization of dietary energy by rumen microbes and the increased protein synthesis, due to the higher digestibility of the fibrous fractions, would have led to a decrease in ammonia and therefore urea in the milk. This outcome agreed with the findings of Tajima et al. (38) who reported an increase of rumen cellulolytic bacteria and a decrease of acidotic flora in diet containing fresh forage compared to grain-based diets. Moreover, significantly higher estimated mozzarella cheese yield was recorded in the treated group probably due to the lower MUN, in agreement with the results of Bittante and Cipolat-Gotet (39) who found a significant correlation between high MUN and milk longer rennet coagulation time, weaker curd, and lower mozzarella yield (see Table 7).

Several feeding strategies have already been demonstrated to improve economic sustainability of buffalo farm (40). In the context of the trial, the utilization of sorghum is scheduled during the late spring and summer months, which correspond with the period of higher milk production. The inclusion of green fodder in the diet should resulted to be economically advantageous according to the on-going market trends. The saving obtained was 0.27 EUR/head/day (EUR 5.4/day/group). Therefore, it is estimated that for a mean buffalo farm with 300 buffaloes, the saving would be € 81 per day, which would amount to approximately € 2,500 per month. Furthermore, according to the equation proposed by Altiero et al. (19), the estimated mozzarella yield was greater in group S compared with group C. Moreover, the improved mozzarella yields should also contribute to lowering whey disposal expenses.

Finally, the diet with green sorghum might result in a lower environment impact; indeed, reducing the use of corn silage is supposed to decrease water and energy consumption for irrigation. In addition, Benchaar et al. (41), reported a reduction in methane production by 15 and 21% by using forage with higher digestibility as was the green fodder sorghum in present trial, thus contributing to achieve SDG 13.

This study provides evidence that the inclusion of green fodder sorghum in the diet of lactating buffalo cows could represent an effective feeding strategy. Its adoption does not adversely affect daily dry matter intake or milk yield, while it significantly enhances milk fat concentration and reduces milk urea content. From an economic standpoint, the use of green fodder sorghum should contribute to a reduction in feeding costs and an improvement in cheese yield, thereby offering tangible economic advantages for producers. Furthermore, the overall environmental impact along the production chain could be mitigated, primarily due to lower irrigation and energy requirements. In conclusion, the inclusion of green sorghum into the diet of lactating buffaloes may constitute a sustainable and economically advantageous approach; nonetheless, further research is warranted to investigate the effects of higher inclusion levels of this feed resource.