An experiment was conducted to examine effects of supplemental lysophospholipids (LPL) in dairy cows. Eight ruminally cannulated lactating Holstein cows were used in a replicated 4 × 4 Latin square design. Dietary treatments were (1) a dairy ration [CON; 55% forage and 45% concentrate on a dry matter (DM) basis], (2) a positive control diet supplemented with monensin (MON; 16 mg/kg in dietary DM; Elanco Animal Health, Greenfield, IN], (3) a control diet supplemented with low LPL (0.05% of dietary DM; Lipidol Ultra, Easy Bio Inc., Seoul, South Korea), and (4) a control diet supplemented with high LPL (0.075% of dietary DM). Experimental periods were 21 d with 14-d diet adaptation and 7-d sample collection. Daily intake and milk yield were measured and rumen contents were collected for fermentation characteristics and bacterial population. Spot urine and fecal samples (8 samples/ cow per period) were collected to determine nutrient digestibility and dietary N utilization. All data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC; group and cow within group were random effects and treatments, time, and their interaction were fixed effects). Preplanned contrasts were made to determine effect of MON versus CON, effect of LPL versus MON, and linear effect of increasing LPL. In the current study, responses to MON generally agreed with effects of monensin observed in the literature (increased milk yield and feed efficiency but decreased milk fat content). Supplementation of LPL to the diet did not alter DM intake but linearly increased milk yield, resulting in increases in feed efficiency (milk yield/DM intake) and milk protein and fat yields. However, total-tract digestibility of DM and organic matter tended to be lower (60.9 vs. 62.2% and 61.8 vs. 63.1%, respectively) for LPL compared with CON. Linear increases in milk N secretion and decreases in urinary N excretion were observed with increasing LPL in the diet. A slight decrease in acetate proportion in the rumen for LPL was found. Relative to MON, very few bacteria in the rumen were affected with increasing LPL. In conclusion, LPL is a potential feed additive that can increase milk yield and components and dietary N utilization. However, more studies with large numbers of animals are needed to confirm the effect of LPL on production. Similar positive effects on production were observed between LPL and MON, but individual mechanisms were likely different according to ruminal fermentation characteristics. Further studies are needed to explore the mode of action of LPL in dairy cows.

No abstract

No abstract

Indirect methods of spot sampling with intrinsic markers to estimate fecal output and nutrient digestibility often have been used in dairy nutrition research as alternatives to total collection of feces (TC) because of labor and expense. However, fecal output and nutrient digestibility estimated from the indirect method must be accurate regardless of altering dietary conditions. This experiment was designed to validate the accuracy of using indigestible neutral detergent fiber (iNDF) or acid-insoluble ash (AIA) as intrinsic markers to estimate fecal outputs and nutrient digestibility compared with TC and to determine the optimal number of spot sampling events to accurately determine fecal output and then nutrient excretion. The experiment used 12 multiparous lactating Holstein cows in a randomized complete block design. Cows were blocked by days in milk and milk yield and randomly assigned to 1 of 2 diets: a diet containing about 49% corn silage on a dry matter basis and a diet containing about 48% alfalfa silage with high by-product (soyhulls) and supplemental K. During the final 3 d of 21-d periods, TC was performed, and 12 spot samples were collected for the same 3 d to represent every 2 h in a 24-h cycle. Fecal outputs and nutrient digestibility of dry matter, organic matter, or nitrogen estimated with iNDF or AIA as an intrinsic marker were compared with TC. Overall, fecal outputs and digestibility estimated with iNDF were similar to that estimated with TC, whereas AIA overestimated fecal output by 44 to 61% and underestimated nutrient digestibilities by 16 to 32%. However, potential differences in statistical inference of dietary effects between iNDF and TC were found. Data from individual spot samples were aggregated to represent spot sampling frequencies of 12 (SP12), 6 (SP6), 4 (SP4), or 2 (SP2) evenly spaced events starting at feeding time. Compared with TC, SP12 produced similar fecal content of iNDF, organic matter, and nitrogen, but fecal AIA content was greater. Furthermore, compared with SP12, SP6 produced similar fecal content of all nutrients, whereas marker and nutrient concentrations in SP4 and SP2 were different. In this experiment, iNDF was a better fecal marker than AIA, and a spot sampling frequency of at least 6 events was necessary. However, interpretation of dietary effects could be confounded when iNDF was used to estimate fecal outputs.

This study investigated the effects of continuous feeding of high inclusion of reduced-fat corn distillers grains with solubles with and without monensin on dry matter intake (DMI), production, milk fatty acid profile, and plasma AA profile in lactating cows. The experiment was conducted for 12 wk (1-wk covariate, 2-wk diet adaptation, and 9-wk experimental period of data collection) with 36 Holstein cows in a randomized complete block design. Cows were blocked by parity, days in milk, and milk yield and assigned to the following diets: (1) control (CON), (2) CON with reduced-fat corn distillers grains with solubles included at 28.8% (dry matter basis) replacing soybean meal, soyhulls, and supplemental fat (DG), and (3) DG with monensin (Rumensin; Elanco Animal Health, Greenfield, IN) supplemented at a rate of 20 mg/kg of DM offered (DGMon). Orthogonal contrasts were used to compare CON versus DG and DGMon and to compare DG versus DGMon. Milk yield was not affected (40.3 vs. 40.8 kg/d) by DG and DGMon compared with CON. However, for DG and DGMon compared with CON, decreased DMI (24.9 vs. 26.4 kg/d), milk fat yield (1.12 vs. 1.55 kg/d), milk protein yield (1.24 vs. 1.32 kg/d), and energy-corrected milk yield (37.7 vs. 43.5 kg/d) were observed. Feeding DGMon compared with DG did not affect DMI (24.4 vs. 25.4 kg/d) and milk yield (39.2 vs. 41.3 kg/d) but decreased milk fat yield (1.08 vs. 1.23 kg/d), milk protein yield (1.20 vs. 1.28 kg/d), and energy-corrected milk yield (36.0 vs. 39.4 kg/d). Interactions between treatment and week for DMI, milk fat yield, and energy-corrected milk indicate that production responses to DG and DGMon versus CON were decreased over the experimental period. Cows fed DG and DGMon had increased milk fat concentration of trans-10,cis-12 18:2, trans-10 18:1, and long-chain (>16C) and polyunsaturated fatty acids and decreased short-chain (<16C) and odd- and branched-chain fatty acids compared with CON. No difference was observed between DG and DGMon in milk fatty acid profile. In the current study, feeding a high-DG diet did not sustain DMI and production, and supplementing monensin to a high-DG diet further decreased DMI and production.

No abstract

A long-term experiment was conducted to examine the effects of feeding encapsulated nitrate (EN) on growth, enteric methane production, and nitrate (NO) toxicity in beef cattle fed a backgrounding diet. A total of 108 crossbred steers (292 ± 18 kg) were blocked by BW and randomly assigned to 18 pens. The pens (experimental unit; 6 animals per pen) received 3 dietary treatments: Control, a backgrounding diet supplemented with urea; 1.25% EN, control diet supplemented with 1.25% encapsulated calcium ammonium NO (i.e., EN) in dietary DM, which partially replaced urea; or 2.5% EN, control diet supplemented with 2.5% EN (DM basis) fully replacing urea. Additionally, 24 steers were located in 4 pens and randomly assigned to 1 of the above 3 dietary treatments plus a fourth treatment: 2.3% UEN, control diet supplemented with 2.3% unencapsulated calcium ammonium NO (UEN) fully replacing urea. Animals in the additional 4 pens were used for methane measurement in respiratory chambers, and the pens (except UEN) were also part of the performance study (i.e., = 7 pens/treatment). The experiment was conducted for 91 d in a randomized complete block design. During the experiment, DMI was not affected by inclusion of EN in the diet. Feeding EN had no effect on BW, ADG, and G:F ( ≥ 0.57). Methane production (g/d) tended to decrease ( = 0.099) with EN and UEN, but yield (g/kg DMI) did not differ ( = 0.56) among treatments. Inclusion of EN in the diet increased ( ≤ 0.02) sorting of the diets in favor of large and medium particles and against small and fine particles, resulting in considerable increases in NO concentrations of orts without affecting DMI. Plasma NO-N and NO-N concentrations increased ( ≤ 0.05) for EN compared with Control in a dose response manner, but blood methemoglobin levels were below the detection limit. Nitrate concentration in fecal samples slightly increased (from 0.01% to 0.14% DM; < 0.01) with increasing levels of EN in the diet. In conclusion, EN can be used as a feed additive replacing urea in beef cattle during a backgrounding phase in the long term without NO intoxication or any negative effects on growth performance. In addition, the study confirmed that feeding EN tended to decrease enteric methane production in the long term.

The objective of the experiment was to examine effects of a diet containing a high concentration (28.8% dry matter basis) of corn distillers grain with solubles on manure characteristics and NH 3 and H 2 S emissions from dairy cow manure. Eighteen cows were blocked by parity and days in milk, and cows in each block were assigned to the following treatments: the control diet (CON) or CON with distillers grains with solubles at 28.8% (dry matter basis) replacing mainly soybean meal (DG). The experiment was conducted for 11 wk, and feces and urine from individual cows were collected over 3 d in wk 11 (a total of 8 spot samples per cow). Fecal or urine samples were composited by cow, and the composite feces and urine were analyzed for indigestible neutral detergent fiber and creatinine concentration, respectively, for individual cows to estimate total fecal and urine outputs. Immediately before the manure incubation, composited feces and urine were sampled to determine manure characteristics. Manure was reconstituted according to daily fecal and urine excretion estimated for individual cows. Individual manures were incubated using a continuous air flux multichamber system over 10 d to measure NH 3 and H 2 S emissions. All data from 18 manures were analyzed using the Mixed procedure of SAS (SAS Institute Inc., Cary, NC). The ratio of feces to urine and the contents of manure total and volatile solids were not different among treatments. Urine from DG had lower pH and DG manure had lower N content and greater S content compared with CON. During the 10-d incubation, NH 3 emission was considerably less for DG versus CON. The emission of H 2 S over 10 d for DG was greater compared with that for CON. After the incubation, manure pH and N and S concentrations were greater for DG versus CON. In conclusion, manure from cows fed a high-DG diet decreased urinary N contribution to manure N and lowered urine pH, which were the factors that caused the decrease in NH 3 emission from DG manure. However, the DG diet increased dietary S concentration and increased S excretion in urine and feces. This increased H 2 S emission from DG manure during the 10-d manure incubation.