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Lactational performance in dairy cows receiving a rumen-protected B-vitamin blend during lactation: Regression analysis to evaluate yield, lactation number and days in milk.

E. Evans

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06-24-2020

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Abstract:

W80
Lactational performance in dairy cows receiving a rumen-protected B-vitamin blend during lactation: Regression analysis to evaluate yield, lactation number and days in milk.
E. Evans*2, H. Leclerc1, E. Santin1. 1Jefo St-Hyacinthe, QC, Canada, 2Technical Advisory Services Bowmanville, ON, Canada.

The objective of this study was to evaluate the impact of a rumen-protected blend of B vitamins pantothenic acid, pyridoxine, biotin, folic acid and vitamin B12 (Jefo, Canada) on milk, fat and protein yield in cows and to evaluate the effects of current yield, lactation number and days in milk (DIM). The analysis utilized 5043 observations from 50 on-farm double reversal studies from 7 countries between 2005 and 2015. The test product was added to the current diet in the center period. Cows included were over 45 d in milk at first milk test, and available for all milk collection periods (minimum 28 d). Data were analyzed using a regression model in Minitab 16 (Minitab LLC) with random effects of study, period, days in milk and lactation number. Overall results are provided in Table 1 and an overall description of results is provided in the equation: Milk yield with B vitamin blend = 4.05 + 0.917 � current milk −0.0063 � DIM + 0.246 � lactation number (R2 = 0.798). Current milk yield had a significant effect on response to the B vitamins blend in both primiparous (R2 = 0.72) and multiparous cows (R2 = 0.80). Milk yield and fat yield increased with supplementation, and the extent of change was determined to increase with lactation number (P < 0.05). Protein yield increased with the B vitamins blend and was unaffected by lactation number (P < 0.05). Responses to the supplementation were found to decline with DIM for milk, fat and protein yield, but to increase for fat and protein percent relative to control (P < 0.05). Results indicated that dairy cows responded positively to the inclusion of the rumen protected B vitamin blend with differences in the extent of the response due to lactation number, days in milk and milk yield.Table 1. Results for all cows from all studies (n = 5,043, DIM =163, Lactation number = 2.20)

ItemTestControlP-value
Milk, L33.1232.22<0.001
Fat, %3.723.700.236
Protein, %3.233.22<0.551
Fat, kg1.221.17<0.001
Protein, kg1.051.02<0.001

Keywords: B vitamins, meta regression, lactational performance.