title: Management, nutrition, and lactation performance are related to bulk tank milk de novo fatty acid concentration on northeastern US dairy farms.
abstract: This study investigated the relationship of management practices, dietary characteristics, milk composition, and lactation performance with de novo fatty acid (FA) concentration in bulk tank milk from commercial dairy farms with Holstein, Jersey, and mixed-breed cows. It was hypothesized that farms with higher de novo milk FA concentrations would more commonly use management and nutrition practices known to optimize ruminal conditions that enhance de novo synthesis of milk FA. Farms (n=44) located in Vermont and northeastern New York were selected based on a history of high de novo (HDN; 26.18±0.94g/100g of FA; mean ± standard deviation) or low de novo (LDN; 24.19±1.22g/100g of FA) FA in bulk tank milk. Management practices were assessed during one visit to each farm in March or April, 2014. Total mixed ration samples were collected and analyzed for chemical composition using near infrared spectroscopy. We found no differences in days in milk at the farm level. Yield of milk fat, true protein, and de novo FA per cow per day were higher for HDN versus LDN farms. The HDN farms had lower freestall stocking density (cows/stall) than LDN farms. Additionally, tiestall feeding frequency was higher for HDN than LDN farms. No differences between HDN and LDN farms were detected for dietary dry matter, crude protein, neutral detergent fiber, starch, or percentage of forage in the diet. However, dietary ether extract was lower for HDN than LDN farms. This research indicates that overcrowded freestalls, reduced feeding frequency, and greater dietary ether extract content are associated with lower de novo FA synthesis and reduced milk fat and true protein yields on commercial dairy farms.
authors: Department of Animal and Veterinary Science, University of Vermont, Burlington 05405; William H. Miner Agricultural Research Institute, Chazy, NY 12921.
authors: M E
authors: ME
authors: Woolpert
authors: William H. Miner Agricultural Research Institute, Chazy, NY 12921.
authors: H M
authors: HM
authors: Dann
authors: William H. Miner Agricultural Research Institute, Chazy, NY 12921.
authors: K W
authors: KW
authors: Cotanch
authors: Department of Food Science, Cornell University, Ithaca, NY 14853.
authors: C
authors: C
authors: Melilli
authors: Department of Animal Science, Cornell University, Ithaca, NY 14853.
authors: L E
authors: LE
authors: Chase
authors: William H. Miner Agricultural Research Institute, Chazy, NY 12921. Electronic address: grant@whminer.com.
authors: R J
authors: RJ
authors: Grant
authors: Department of Food Science, Cornell University, Ithaca, NY 14853.
authors: D M
authors: DM
authors: Barbano
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D002138:Calibration; D002417:Cattle; D003612:Dairying; D004032:Diet / Q000662:veterinary*; D004041:Dietary Fats / Q000032:analysis; D004043:Dietary Fiber / Q000008:administration & dosage / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis*; D005260:Female; D007774:Lactation; D007785:Lactose / Q000032:analysis; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis; D009518:New York; D009752:Nutritional Status; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared; D013213:Starch / Q000008:administration & dosage / Q000737:chemistry; D014707:Vermont
chemical_list: D004041:Dietary Fats; D004043:Dietary Fiber; D005227:Fatty Acids; D008894:Milk Proteins; D013213:Starch; D007785:Lactose
keywords: de novo fatty acid; feeding management; milk fat; stocking density; true protein