Management practices, physically effective fiber, and ether extract are related to bulk tank milk de novo fatty acid concentration on Holstein dairy farms

Abstract

The objective of this study was to evaluate the relationship of management practices and dietary factors with de novo fatty acid concentration in bulk tank milk from commercial dairy farms milking Holstein cows. Farms were selected based on de novo fatty acid concentration during the 6 mo before the farm visit and were categorized as high de novo (HDN; 24.61 ± 0.75 g/100 g of fatty acids, mean ± standard deviation; n = 19) or low de novo (LDN; 23.10 ± 0.88 g/100 g of fatty acids; n = 20). Farms were visited once in February, March, or April 2015 and evaluated based on management and facility design known to affect cow behavior, physical and chemical characteristics of the diet, and ration formulation and forage analyses obtained from the farm's nutritionist. We observed no differences between HDN and LDN farms in farm size, time away from the pen for milking, days in milk, or body condition score. We detected no differences between HDN and LDN farms in milk fat or true protein yield; however, milk fat and protein content and de novo fatty acid yield per day were higher for HDN farms, as was gross income per unit of milk sold. High de novo farms tended to be more likely to deliver fresh feed twice versus once per day, have a freestall stocking density ≤110%, and provide ≥46 cm of feed bunk space per cow. We observed no detectable differences in forage quality or ration dry matter, crude protein, or starch content. However, ether extract was lower and physically effective neutral detergent fiber was higher for HDN farms. Feeding management, stocking density, dietary ether extract content, and the physical characteristics of the diet are related to de novo fatty acid, fat, and protein concentration in bulk tank milk from high-producing Holstein dairy farms.

Short communication: Field study to investigate the associations between herd-level risk factors for milk fat depression and bulk tank milk fat percent in dairy herds feeding monensin

“…Descriptive statistics for milk FA profile of bulk tank samples are presented in Table 1. In the current study, we observed generally positive relationships of de novo-synthesized short-chain FA with herd milk fat percentage (P = 0.002; R 2 = 0.12), consistent with the previous observations (Barbano et al, 2014;Woolpert et al, 2016Woolpert et al, , 2017. We also noted a generally negative relationship of trans C18:1 isomers that are produced by other alternate pathways of ruminal biohydrogenation with herd milk fat percentage.…”

Evolution of the bovine milk fatty acid profile – From colostrum to milk five days post parturition

“…Days post parturition had a significant effect on the de novo fatty acid index (C4:0 to C15:0) (p = 0.028). De novo fatty acids, which are the fatty acids synthesised in the cows mammary gland from the volatile fatty acids acetate and butyrate, have increasingly been used as an indicator of rumen function on commercial dairy farms (Woolpert et al, 2017).…”

The milk fingerprint of Sardinian dairy sheep: quality and yield of milk used for Pecorino Romano P.D.O. cheese production on population-based 5-year survey

“…To compensate pasture quality variability and scarcity, sheep farms usually integrate animal diets with grain and mixes concentrates from both local and international markets. It has to be noticed that milk FA composition is also related to the herbage quality and to the intake of glucogenic and lipogenic carbohydrates; elevated intake of FA precursors from high digestible forages is associated with increases in de novo FA (Woolpert et al 2017). Thus, an increase in de novo FA is expected in winter and early-spring with high herbage availability and intake, whereas a decrease is expected late-spring and summer because the lower pasture fibre quality.…”