title: Short communication: Effect of dietary manipulation of crude protein content and nonfibrous-to-fibrous-carbohydrate ratio on energy balance in early-lactation dairy cows.
abstract: Disparities between nutrient intake and demand often result in a state of negative energy balance (EB) in the early-lactation dairy cow. Reducing dietary crude protein (CP) content and providing glucogenic nutrients may overcome this issue. This study evaluates whether or not offering a diet lower in CP and higher in nonfiber carbohydrates (LP-NFC) can improve EB and the metabolic status of the early-lactation dairy cow compared with a diet higher in CP and fibrous carbohydrates (HP-FC). Twenty Holstein-Friesian dairy cows were assigned to 1 of 2 dietary treatments in a randomized block design. Diets were isoenergetic (6.57 MJ of net energy for lactation) and formulated to contain 15% CP and 6% starch (HP-FC), or 12% CP and 28% starch (LP-NFC) and were offered for the first 63 d of lactation. Intake and milk yield were determined daily, whereas milk and blood samples, weights, and body condition scores were collected weekly. Intakes (mean ± standard errors of the mean, SEM) of dry matter (17.4 ± 0.6 kg/d) and energy (113.0 ± 4.6 MJ of net energy for lactation) were not different between treatments. However, the HP-FC group had a higher milk yield (31.8 vs. 28.9 ± 1.4 kg/d) and a lower EB compared with the LP-NFC group. Blood urea N concentration (3.5 vs. 1.8 ± 0.2 mmol/L) was higher, whereas bilirubin (6.0 vs. 6.7 ± 0.2 mmol/L) and β-hydroxybutyrate concentrations (0.7 vs. 0.8 ± 0.05 mmol/L) were lower in the HP-FC group compared with the LP-NFC group. These data suggest that EB can be improved during early lactation through the manipulation of milk output by offering a lower CP, higher NFC diet.
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Lyons Research Farm, Newcastle, Dublin, Ireland.
authors.forename: S J
authors.initials: SJ
authors.lastname: Whelan
authors.affiliation: School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: finbar.mulligan@ucd.ie.
authors.forename: F J
authors.initials: FJ
authors.lastname: Mulligan
authors.affiliation: School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: V
authors.initials: V
authors.lastname: Gath
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Lyons Research Farm, Newcastle, Dublin, Ireland.
authors.forename: B
authors.initials: B
authors.lastname: Flynn
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Lyons Research Farm, Newcastle, Dublin, Ireland.
authors.forename: K M
authors.initials: KM
authors.lastname: Pierce
mesh_terms: D020155:3-Hydroxybutyric Acid; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology; D004032:Diet / Q000662:veterinary*; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D004043:Dietary Fiber / Q000008:administration & dosage / Q000494:pharmacology*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D007774:Lactation; D008892:Milk / Q000378:metabolism; D013213:Starch / Q000378:metabolism
chemical_list: D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D004044:Dietary Proteins; D013213:Starch; D020155:3-Hydroxybutyric Acid
keywords: carbohydrate; dairy cow; early lactation; energy balance