Ration formulations containing reduced-fat dried distillers grains with solubles and their effect on lactation performance, rumen fermentation, and intestinal flow of microbial nitrogen in Holstein cows.
Sixteen multiparous lactating Holstein cows were used in 2 experiments to evaluate the effects of reduced-fat dried distillers grains with solubles (RFDG) on milk production, rumen fermentation, intestinal microbial N flow, and total-tract nutrient digestibility. In experiment 1, RFDG was fed at 0, 10, 20, or 30% of diet dry matter (DM) to 12 noncannulated Holstein cows (mean ± standard deviation: 89 ± 11 d in milk and 674 ± 68.2 kg of body weight) to determine effects on milk production. In experiment 2, the same diets were fed to 4 ruminally and duodenally cannulated Holstein cows (mean ± standard deviation: 112 ± 41 d in milk; 590 ± 61.14 kg of body weight) to evaluate the effects on rumen fermentation, intestinal flow of microbial N, and total-tract nutrient digestibility. In both experiments, cows were randomly assigned to 4 × 4 Latin squares over 21-d periods. Treatments (DM basis) were (1) control (0% RFDG), (2) 10% RFDG, (3) 20% RFDG, and (4) 30% RFDG. Feed intake and milk yield were recorded daily. In both experiments, milk samples were collected on d 19 to 21 of each period for analysis of milk components. In experiment 2, ruminal pH was measured; samples of rumen fluid, duodenal digesta, and feces were collected on d 18 to 21. Microbial N was estimated by using purines and DNA as microbial markers. Milk yield was not affected by treatment and averaged 34.0 ± 1.29 kg/d and 31.4 ± 2.81 kg/d in experiments 1 and 2, respectively. Percentage of milk protein tended to increase in experiment 1; estimates were 3.08, 3.18, 3.15, and 3.19 ± 0.06% when RFDG increased from 0 to 30% in the diets. However, milk protein concentration was not affected in experiment 2 and averaged 3.02 ± 0.07%. Percentage of milk fat was not affected and averaged 3.66 ± 0.05% and 3.25 ± 0.14% in experiments 1 and 2, respectively. Total ruminal volatile fatty acids and ammonia concentrations were not affected by treatment and averaged 135.18 ± 6.45 mM and 18.66 ± 2.32 mg/dL, respectively. Intestinal microbial N flow was not affected by treatment; however, purines yielded higher estimates of flow compared with DNA markers. When averaged across treatments, intestinal flow of microbial N was 303 and 218 ± 18 g of N/d, using purines and DNA as the markers. Dry matter, organic matter, neutral detergent fiber, and nonfiber carbohydrate digestibility tended to increase with increasing inclusion of RFDG. Results from these experiments indicate that dairy rations can be formulated to include up to 30% RFDG while maintaining lactation performance, volatile fatty acids concentration, and intestinal supply of microbial N.
Department of Animal Science, University of Nebraska-Lincoln, Lincoln 68583-0908.
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Castillo-Lopez
Department of Animal Science, University of Nebraska-Lincoln, Lincoln 68583-0908.
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Ramirez Ramirez
Department of Animal Science, University of Nebraska-Lincoln, Lincoln 68583-0908.
T J
TJ
Klopfenstein
Department of Veterinary and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln 68583-0908.
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Hostetler
Dakota Gold Research Association, Sioux Falls, SD 57104-4506.
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Karges
Department of Animal Science, University of Nebraska-Lincoln, Lincoln 68583-0908.
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Fernando
Department of Animal Science, University of Nebraska-Lincoln, Lincoln 68583-0908. Electronic address: pkononoff2@unlnotes.unl.edu.
P J
PJ
Kononoff
D000641:Ammonia / Q000032:analysis; D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002417:Cattle; D004032:Diet / Q000662:veterinary; D004041:Dietary Fats / Q000008:administration & dosage; D004043:Dietary Fiber / Q000008:administration & dosage; D002523:Edible Grain; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005260:Female; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology; D007774:Lactation; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis; D009584:Nitrogen / Q000378:metabolism*; D010316:Particle Size; D012417:Rumen / Q000378:metabolism* / Q000382:microbiology*
D004041:Dietary Fats; D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; D008894:Milk Proteins; D000641:Ammonia; D009584:Nitrogen
distillers grains with solubles; intestinal microbial N; lactation; total-tract nutrient digestibility