Effect of dietary tannin supplementation on cow milk quality in two different grazing seasons

Abstract

Extensive farming systems are characterized by seasons with different diet quality along the year, as pasture availability is strictly depending on climatic conditions. A number of problems for cattle may occur in each season. Tannins are natural polyphenolic compounds that can be integrated in cows’ diet to overcome these seasonal problems, but little is known about their effect on milk quality according to the season. This study was designed to assess the effects of 150 g/head × day of tannin extract supplementation on proximate composition, urea, colour, cheesemaking aptitude, antioxidant capacity, and fatty acid (FA) profile of cow milk, measured during the wet season (WS) and the dry season (DS) of Mediterranean climate. In WS, dietary tannins had marginal effect on milk quality. Conversely, in DS, the milk from cows eating tannins showed 10% lower urea and slight improvement in antioxidant capacity, measured with FRAP and TEAC assays. Also, tannin extract supplementation in DS reduced branched-chain FA concentration, C18:1 t10 to C18:1 t11 ratio and rumenic to linoleic acid ratio. Tannins effect on rumen metabolism was enhanced in the season in which green herbage was not available, probably because of the low protein content, and high acid detergent fibre and lignin contents in diet. Thus, the integration of tannin in the diet should be adapted to the season. This could have practical implications for a more conscious use of tannin-rich extracts, and other tannin sources such as agro-industrial by-products and forages.

Impact of diet supplemented with microencapsulated condensed tannins on cow milk nutritional profile

“…In a recent work, it was shown that the dietary tannin supplementation on cow's diet improved both the reducing power and the radical scavenging capacity of milk probably because they have an indirect effect in preserving antioxidants (Menci et al . 2021).…”

Polyphenols for Livestock Feed: Sustainable Perspectives for Animal Husbandry?

“…These findings were further confirmed by supplementing a dose equal to 200 g/cow/day of quebracho tannin extract [146], when milk yield was decreased by 14.5%. It was observed that an increase in quebracho-chestnut tannin mixture was related to a linear decline in milk protein content [147], whereas chestnut and quebracho tannic extracts, during different seasonal diets (wet and dry), improved milk quality by enhancing antioxidant and reducing efficacy [148]. Most of the data in the literature reported no significant effects of bayberry and Acacia mangium CTs, valonia HTs, chestnut-tannin extract, hazel leaves, and hazelnut skin on MY [149][150][151][152].…”

“…In the light of studies analysed in the last 5 years (Table 1), in some cases the integration of polyphenols, mainly extracts rich in tannins, favours an increase in milk yield of more than 10% [120,133,142,148,158], with a positive impact on the chemical composition of fatty acid, protein and lactose modifications. The positive effect on milk production could also be strongly linked to the ability of these extracts to modulate the stressors that often lead to an inflammatory state during the transition period.…”