Abstract #534
Section: Ruminant Nutrition (orals)
Session: Ruminant Nutrition 7
Format: Oral
Day/Time: Wednesday 2:00 PM–2:15 PM
Location: Room 233
Session: Ruminant Nutrition 7
Format: Oral
Day/Time: Wednesday 2:00 PM–2:15 PM
Location: Room 233
# 534
The effects of isoenergetic high-starch or high-fat diets on energy and nitrogen partitioning and utilization in late-lactation Jersey cows.
D. L. Morris*1, T. M. Brown-Brandl2, K. E. Hales3, K. J. Harvatine4, P. J. Kononoff1, 1Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE, 2Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE, 3USDA Agricultural Research Service, US Meat Animal Research Center, Clay Center, NE, 4Department of Animal Science, The Pennsylvania State University, University Park, PA.
Key Words: starch, fat, energy
The effects of isoenergetic high-starch or high-fat diets on energy and nitrogen partitioning and utilization in late-lactation Jersey cows.
D. L. Morris*1, T. M. Brown-Brandl2, K. E. Hales3, K. J. Harvatine4, P. J. Kononoff1, 1Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE, 2Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, NE, 3USDA Agricultural Research Service, US Meat Animal Research Center, Clay Center, NE, 4Department of Animal Science, The Pennsylvania State University, University Park, PA.
The objectives were to determine the effects of an isoenergetic high-starch or high-fat diet on energy and N partitioning and utilization. Twelve multiparous Jersey cows (192 ± 11 d in milk) in a crossover design with 28-d periods (24-d adaptation and 4-d collection) were used to compare a high-starch (STA; 30.8% starch, 31.8% NDF, 2.5% crude fat) or high-fat (HFA; 16.8% starch, 41.7% NDF, 4.3% crude fat) diet. Nutrient composition was varied primarily by replacing corn grain in STA with a rumen-inert fat source and cottonseed hulls in HFA. Data were analyzed with a model that included the fixed effect of treatment and the random effect of period, cow, and error. Gross energy content was lower (P < 0.02) for STA compared with HFA (4.43 vs. 4.54 ± 0.01 Mcal/kg of DM); while, digestible (2.93 vs. 2.74 ± 0.04 Mcal/kg of DM), metabolizable (2.60 vs. 2.41 ± 0.03 Mcal/kg of DM) and net (1.89 vs. 1.70 ± 0.04 Mcal/kg of DM) energy content were all greater. Tissue energy deposit as body fat tended (P = 0.12) to be greater for STA compared with HFA (5.41 vs. 2.51 ± 1.16 Mcal/d). Compared with HFA, STA increased (P = 0.03) milk N secretion (141 vs. 131 ± 10.5 g/d) and decreased (P < 0.01) urinary N excretion (123 vs. 150 ± 6.4 g/d). Compared with HFA, STA increased (P < 0.01) apparent total-tract digestibility of DM (66.7 vs. 61.7 ± 1.06%), energy (66.0 vs. 60.4 ± 0.92%), and 18 carbon fatty acids (67.9 vs. 61.2 ± 1.60%), and decreased (P < 0.01) starch digestibility (97.0 to 94.5 ± 0.48%). Compared with HFA, STA tended (P < 0.15) to increase milk yield (19.7 vs. 18.9 ± 1.38 kg/d), milk protein content (4.03 vs. 3.93 ± 0.10%), and milk protein yield (0.79 vs. 0.74 ± 0.05 kg/d. In addition, STA compared with HFA decreased (P < 0.01) milk fat content (5.93 vs 6.37 ± 0.15%) but did not affect (P > 0.29) milk fat yield (1.19 ± 0.09 kg/d) or energy-corrected milk yield (27.2 ± 1.99 kg/d). Our results suggest that STA had a greater net energy content, increased partitioning of energy toward tissue energy deposit as fat, and partitioning of N toward milk secretion and away from urinary excretion.
Key Words: starch, fat, energy
