Partial Substitution of Soybean Meal with a Yeast-Fermented Vinasse Protein Source: Effects on Milk Yield, Composition, and Serum Biochemistry in Crossbred Dairy Cows

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Akdağ A.

METABOLITES, vol.16, pp.1-13, 2026 (SCI-Expanded, Scopus)

  • Publication Type: Article / Article
  • Volume: 16
  • Publication Date: 2026
  • Doi Number: 10.3390/metabo16080518
  • Journal Name: METABOLITES
  • Journal Indexes: Natural Science Collection (ProQuest), Biological Science Database (ProQuest), Scopus, Science Citation Index Expanded (SCI-EXPANDED), BIOSIS, Chemical Abstracts Core, EMBASE, Directory of Open Access Journals
  • Page Numbers: pp.1-13
  • Open Archive Collection: AVESIS Open Access Collection
  • Eskisehir Osmangazi University Affiliated: Yes

Abstract

Background/Objectives: This study aimed to compare the effects of two distinct dietary

protein sources, soybean meal (SBM, 454 g CP/kg dry matter [DM]) and fermented protein

source (FPS, 635 g CP/kg DM), on milk yield (MY), milk quality traits, and serum biochemistry

in crossbred dairy cows. Methods: This study employed a randomized complete

block design with four groups (n = 6 per group): Control (120 g/kg SBM), FPS30 (30 g/kg

FPS and 75 g/kg SBM), FPS40 (40 g/kg FPS and 60 g/kg SBM), and FPS50 (50 g/kg FPS

and 45 g/kg SBM). Results: After 66 days (21-day adaptation period and 45-day feeding

trial), DM intake, milk protein content, and milk density did not differ significantly

across groups. However, MYs were significantly higher in the FPS50 group (p = 0.043).

Additionally, milk fat (p = 0.021), DM (p = 0.013), solids-non-fat (SNF, p = 0.047), and

lactose content (p = 0.007) were significantly higher in the FPS groups. Although serum

biochemistry did not differ across groups on day 0, blood urea nitrogen (BUN, p = 0.044)

and serum Ca (p = 0.041), P (p = 0.039), and Mg (p = 0.041) concentrations were significantly

lower in the FPS groups on day 66. Moreover, FPS intake correlated positively with MY

(R = 0.680), milk DM (R = 0.706), fat (R = 0.665), SNF (R = 0.566), lactose content (R = 0.653),

and fat-to-protein ratio (R = 0.507) and negatively with milk density (R = −0.429) and

mineral content (R = −0.271). Conclusions: These findings indicate that FPS is effective in

increasing productivity and improving/maintaining milk quality traits in cows fed diets

substituting specific amounts of SBM with FPS. The induced reduction in BUN can be

interpreted as increased protein utilization.