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Byproducts in livestock diets have the potential to reduce the environmental impact of food production and the cost of animal feeding. The objective was to evaluate the extent and rate of nutrient degradability of potato and other byproducts by rumen microorganisms in vitro. Byproducts included barley malt sprouts, fries, dry peel, and hopper, which were supplied by Performix Nutrition Solutions (Nampa, ID). Two in vitro incubators (DAISYII, ANKOM Technology) each with four incubation jars were used to evaluate ruminal degradability of dry matter (DM) and neutral detergent fiber (NDF). Each jar contained 1,600 mL buffer solution (ANKOM Technology), 400 mL rumen contents (collected from two ruminally cannulated cows), 14 filter bags (F57, ANKOM Technology) with 0.5 g of ground byproduct, 14 filter bags with 0.5 g of ground corn (standard), and 14 blank bags. Each jar was purged with CO2 and filter bags were incubated at 39°C for 0, 3, 6, 9, 12, 24, and 48 h, then removed, rinsed, dried at 55˚C for 48 h, weighed, and analyzed for DM and NDF. Each byproduct was incubated in 3 jars on two different d (6 replicates). Degradation of DM was separated into fractions A (disappearance at 0 h), C (DM remaining after 48 h) and B (100%-A-C). Rate of degradation for fraction B was the slope of the natural logarithms of the DM disappearance. All byproducts were compared with standard corn grain as the control. Fraction A for DM was not different (P > 0.40) for barley malt sprouts (35.4%) and hopper (33.7%), and less (P < 0.05) for dry peel (27.8%) and fries (13.2%) when compared with corn grain (33.4%). Fraction B for DM was greater (P < 0.05) for fries (74.0%), not different (P = 0.44) for hopper (56.1%), and less (P < 0.05) for dry peel (43.6%) and sprouts (37.0%) when compared with corn grain (53.9%). Rate of DM degradation for fraction B was greater (P < 0.05) for fries (9.9%/h) and hopper (7.0%/h), and not different (P > 0.16) for dry peel (4.6%/h) and sprouts (3.0%/h) when compared with corn grain (3.8%/h). Fraction C for DM was greater (P < 0.05) for dry peel (28.6%) and sprouts (27.6%), and not different (P = 0.20) for fries (12.9%) and hopper (10.3%) when compared with corn grain (12.7%). The indigestible frac- tion of NDF after 48 h of incubation was greatest for dry peel (58.5%), intermediate for sprouts (40.1%) and hopper (36.7%), and least for fries (25.4%; P < 0.05). These results demonstrate that the extent and rate of ruminal DM degradability of various potato and other byproducts differ and may be more or less degradable in the rumen compared with corn grain. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to determine how source of selenium (Se) affects dairy cow performance, antioxidant status, and apparent absorption and retention. Multiparous Holstein cows (n = 24; 597 ± 49 kg BW) were blocked by days in milk (161 ± 18) and randomly assigned to receive 0.3 mg/kg of either: 1) organic Se (selenized yeast; ORG; Sel-Plex-Alltech); or, 2) inorganic Se (sodium selenite; INO) premix, top dressed and mixed into a ration daily. After an 11-week adaptation period (blood and milk sampled monthly), cows received an intraruminal dose of Se77 (either Se77 yeast or NaSe77O3) followed by a 4-day period of blood and rumen fluid sampling, and total collection of feces, urine, and milk. Data were analyzed using PROC GLIMMIX in SAS with fixed effects of treatment, time, and their interaction, and random effect of block. Daily DMI (23 ± 0.6 kg), milk yield (35 ± 1.2 kg), plasma glutathione peroxidase (64 ± 4.2 U), and serum Se (0.11 ± 0.003 µg/g) were not different between treatments during the adaptation period. Serum Se77 maximum concentration and area under the curve (AUC) were not different between treatments for 72 hours following infusion, but rumen fluid Se77 AUC was higher (P = 0.02) for ORG cows. Apparent absorption (64 ± 1.3%) and retention (44 ± 1.5%) of the Se77 dose did not differ between treatments. The ORG cows had lower urinary excretion (13 vs. 17 ± 0.6%; P < 0.01), higher milk excretion (6 vs. 2 ± 0.3%; P < 0.01), and similar fecal excretion (36 ± 1.3%; P = 0.9) of Se77 compared to INO cows. These results indicate that ORG Se increased Se content of milk and decreased Se excretion in urine, but did not alter performance, antioxidant status, and apparent absorption and retention of Se in mid-lactation cows. [ABSTRACT FROM AUTHOR]