Wheat bran as dietary tool to improve dairy production, oxidative status of lactating cows and food sustainability indexes.

Abstract

Wheat bran (WB), an inexpensive by-product widely available in southern Italy, is largely used as component of feed for ruminants, contributing to decrease the use of food suitable for human consumption, thus to improve the sustainability of livestock production. However, the potential benefits of WB, due to its content in polyphenolic compounds, mainly consisted of ferulic acid, in improving rumen conditions and the antioxidant balance of animals, and also providing animal products with functional properties, are not yet well known. Accordingly, this experiment was carried out for 100 days with 36 lactating Italian Simmental cows divided into 3 groups receiving one of 3 concentrates including WB at 0% (WB0), 10% (WB10) or 20% (WB20), formulated to be isoenergetic and isoproteic. During the trial, the group feed intake and the individual milk production were monitored, and cheesemaking of bulk milk were carried out. The diet did not affect milk yield, which was similar among groups throughout the trial. Milk from WB20 group resulted slightly higher in protein and casein, probably promoted by a greater microbial protein synthesis in the rumen, and consequently showed higher clotting time and curd firmness (a2r). In WB20 cows, the higher intake of WB polyphenols, especially ferulic acid, was responsible of a higher blood content of polyphenols, which has had an impact on reactive oxygen metabolites (ROMs), resulted significantly lower in WB20 group than WB0 cows. WB20 cheeses showed, compared to WB0 cheeses, a tendency to have greater total polyphenol content, lower number of peroxides and higher antioxidant capacity, measured as FRAP. The WB20 diet, due to the low cost of WB, reduced the feeding cost for each cow and for kg of milk yield, in comparison with the WB0 diet. In addition, the WB20 group showed the best indexes heFCE (human edible feed conversion efficiency = milk/human edible feed) and NFP (net food production = human edible food - milk), expressed in terms of crude protein or gross energy. In conclusion, the WB ingested by dairy cows at a level of about 12% of total DM intake, as occurred in this experiment with WB20 diet, seems lead to several benefits, such as the improvement of oxidative status of cows, milk quality, shelf-life characteristics and nutraceutical properties of cheese, as well as it can contribute to reduce the feeding cost per unit of product, and limit the human-animal competition for feeding sources.