Case Study - A Reduction of Polyunsaturated Fatty Acid Intake in a Lactating Dairy Cow Herd Increased Milk Fat Percentage

摘要

A 100-cow dairy herd was investigated for chronic milk fat depression. Implementation of traditional measures to reduce the impact of altered rumen fermentation by increasing physically effective fiber intake only partially alleviated the problem. A field study was then performed to quantify the effect of reducing polyunsaturated fatty acid intake on milk fat and milk fatty acid profile. A total of 22 cows randomly selected in the herd were enrolled in the study. Dietary intake of linoleic acid was decreased from 0.609 Lb (277 g) to 0.519 lb (236 g) per cow per day by modifying the ration. The effect of ration reformulation was analyzed in linear regression models using repeated measures within cows. Milk production, milk composition, and milk fatty acid profile data were considered the outcomes. Ration reformulation was associated with an increase of 0.3 percentage points of milk fat (P<0.01) and a concomitant decrease of trans-10, cis-12 conjugated linoleic acid in milk (P<0.001). Results from this case study indicate a small reduction of polyunsaturated fatty acid intake may mitigate milk fat depression in dairy cows.