|Harnly, James - Jim|
Submitted to: Current Developments in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2021
Publication Date: 1/28/2022
Citation: Picklo, M.J., Kalscheur, K., Magnuson, A.D., Bukowski, M.R., Harnly, J.M., Fukagawa, N.K., Finley, J.W. 2022. Identification of high and low branched-chain fatty acid producing phenotypes in Holstein cows following high forage and low forage diets in a cross-over designed trial1. Current Developments in Nutrition. Article nzab154. https://doi.org/10.1093/cdn/nzab154.
Interpretive Summary: Branched chain fatty acids (BCFA) are rumen-derived fatty acids comprising about 2% of bovine milk fatty acids. BCFA possess anti-inflammatory properties and identifying means to enrich the BCFA content of bovine milk may provide human health benefits. We determined in Holstein cows whether the forage content of feed impacts the BCFA content of milk, identified whether some cows produce milk with high BCFA content vs low BCFA content independent of diet, and compared the fatty acid profiles of high BCFA vs low BCFA milks. Our data showed that a higher amount of forage in the cow diet increased the amount of BCFA in milk but that some milks had high BCFA content regardless of forage amount. Moreover, the milks high in BCFA content had a lower concentration of saturated fatty acids that are associated with heart disease in people. Our results demonstrate that the BCFA content of milk is diet-sensitive but that variation in responses suggest other factors such as genotype or rumen microbiome composition play significant roles. The potential to produce milk with high BCFA content and lower SFA content needs further study.
Technical Abstract: Background: Branched chain fatty acids (BCFA) are rumen-derived fatty acids comprising about 2% of bovine milk fatty acids. BCFA possess anti-inflammatory properties and enriching the BCFA content of bovine milk may provide human health benefits. Objective: We determined whether forage content impacts the BCFA content of milk from Holstein cows and identified fatty acid phenotypes in high vs low BCFA-containing milks. Methods: Holstein cows, fed for 67 days in a cross-over design, consumed a diet with high forage and low starch (HF:S) and a diet with low forage and high starch (LF:S). Milk samples were collected at the end of each treatment period and fatty acid content determined. Paired t-tests, one-way ANOVA, sparse partial least squares discriminant analysis (sPLSDA), and Pearson’s correlation analysis were used to analyze the data. Results: The total milk fatty acid concentration for cows fed the HF:S diet was greater than that of cows fed the LF:S diet (4.2 ± 0.7 g/100 mL vs 3.9 ± 0.9 g/100 mL). sPLSDA demonstrated separation of the dietary treatments, with BCFA and odd-chain fatty acids as primary determinants. Total BCFA content was elevated by HF:S intake vs LF:S intake (1.80 vs 1.68 %). Quintile separation of high vs low BCFA milks resulted in 4 groups, HF:S /low BCFA, HF:S /high BCFA; LF:S /low BCFA, and LF:S /high BCFA. Milks from the high BCFA quintiles had lower palmitic acid content (29.6% vs 34.4%) but higher oleic acid content than milks from the low BCFA quintiles (19.7% vs 17.0%). Some cows were identified as high BCFA producers or low BCFA producers regardless of diet. Conclusions: BCFA content of milk is diet-sensitive but variation in responses suggest other factors such as genotype or rumen microbiome composition play significant roles. The potential to produce milk with high BCFA content and lower SFA content needs further study.