Effects of saturated fatty acids with lysophospholipids on production and nutrient digestibility in lactating cows.

The objective of the experiment was to determine the effects of supplemental saturated fatty acid (SFA) sources, lysophospholipids (LPL), and their interaction on production and nutrient digestibility in lactating dairy cows. The experiment was conducted with 48 cows in a randomized complete block design. Cows were blocked (total 12 blocks) by parity and days in milk and randomly assigned to 4 dietary treatments in each block (2 × 2 factorial arrangement), i.e., 2 sources of fat supplements, C16:0 (palmitic acid, PA)- or C18:0 (stearic acid, SA)-enriched fat, with or without LPL. The experiment was conducted for 6 wk to measure daily dry matter intake and milk yield and weekly milk composition. During the last week of the experiment, spot fecal and urine samples were collected to determine total-tract nutrient digestibility. Milk samples in the last week were also collected to analyze for milk fatty acid (FA) profile. All data were analyzed using the mixed procedure of SAS where block was used as a random effect and FA, LPL, and the interaction of FA by LPL were used as fixed effects. Week and interactions of week by FA or LPL were included for production measures. Different sources of SFA did not affect dry matter intake and milk yield. However, PA increased (39.7 vs. 36.8 kg) energy-corrected milk compared with SA due to increased milk fat yield. No effect of LPL on production measures was observed. Total-tract digestibilities of dry matter, organic matter, crude protein, and total FA were not different between PA and SA, but PA increased (41.4 vs. 38.8%) neutral detergent fiber digestibility compared with SA. Supplementation of LPL increased (64.7 vs. 60.5%) total FA digestibility, especially 18-carbon FA (74.1 vs. 68.2%). An interaction of SFA by LPL was found for 16-carbon FA digestibility. The PA diet increased the concentration of 16-carbon FA in milk fat and SA increased the concentration of preformed FA (≥18 carbons). Supplementation of LPL decreased the concentration of trans-10 C18:1. No difference in N utilization and excretion among treatments was observed. In conclusion, PA was more effective in improving milk fat yield of lactating cows compared with SA. Supplementation of LPL increased digestibility of total FA, especially 18-carbon FA but did not affect production.

Effects of corn distillers grains with yeast bodies and manipulation of dietary cation and anion difference on production, nutrient digestibility, and gas emissions from manure in lactating cows.

In a randomized complete block design, 40 lactating Holstein cows (average 98 d in milk and 41 kg/d of milk yield) were randomly assigned to 1 of 4 diets: (1) containing soybean meal as the major protein supplement (CON diet); (2) CON diet with high-protein dried corn distillers grains at 20% on a dry matter (DM) basis by replacing mainly soybean meal (DG diet); (3) DG diet except that high-protein dried corn distillers grains with yeast bodies (extracted after corn ethanol production) was used (DGY diet); or (4) DG diet supplemented with sodium bicarbonate and potassium carbonate to elevate the dietary cation and anion difference (DCAD; DG-DCAD diet). The DCAD of CON, DG, DGY, and DG-DCAD were 185, 62, 67, and 187 mEq/kg of DM, respectively. The experiment began with a 10-d covariate period and then cows were fed the experimental diets for 5 wk (2-wk diet adaptation and 3-wk data collection periods). Dry matter intake and milk yield were measured daily, and spot urine and fecal samples were collected in the last week of the experiment to measure nutrient digestibility; N, S, and P utilization and excretion; and in vitro NH3 and H2S emissions from manure. All data were analyzed using the MIXED procedure of SAS (random effect: block; fixed effects: diets, repeated week, and interactions). During data collection, DM intake was not different among treatment groups, but milk yield tended to be lower (42.4 vs. 39.9 kg/d) for DG, DGY, and DG-DCAD versus CON, which could have been caused by decreases in organic matter and neutral detergent fiber digestibility. Milk protein yield tended to be lower (1.33 vs. 1.24 kg/d) for DG, DGY, and DG-DCAD versus CON. Milk fat yield was lower (1.26 vs. 1.55 kg/d) for DG and DGY versus CON, but that for DG-DCAD (1.43 kg/d) did not differ from CON. Similarly, energy-corrected milk was lower (38.0 vs. 43.3 kg/d) for cows on DG and DGY versus those on CON, but it did not differ between DG-DCAD (40.7 kg/d) and CON. Urinary and fecal N excretion were greater for DG, DGY, and DG-DCAD compared with CON due to greater dietary crude protein content and N intake. However, NH3 emissions did not differ across treatments. Intakes of dietary P and S were greater for DG, DGY, and DG-DCAD, resulting in greater excretion of those in manure and greater H2S emissions from manure compared with CON. These data suggest that the negative effects of feeding distillers grains on production of lactating cows can be partly explained by a decrease in nutrient digestibility (milk yield) and excessive anion load (milk fat). The milk fat response to DG-DCAD suggests that milk fat depression observed with a diet with high content of distillers grains can be partially alleviated by supplementation of cations. In the current study, we observed no beneficial effects of DG containing yeast bodies.

Effects of reducing dietary cation-anion difference on lactation performance and nutrient digestibility of lactating cows and ammonia emissions from manure.

Reducing the dietary cation-anion difference (DCAD) reduces urine pH and, therefore, has potential to lower NH3 emissions from manure. We determined the effects of decreased DCAD on dry matter intake, production, nutrient digestibility, manure characteristics, and NH3 emissions from manure. An in vitro incubation study was conducted to evaluate the degree of reduced urine pH on manure pH and NH3 emissions from manure. In this study, urine pH was directly decreased from 8.5 to 7.5, 6.5, and 5.5 by adding sulfuric acid, which resulted in decreases in manure pH when manure was reconstituted with the fecal-to-urine ratio of 2:1 (as-is basis). The manures from urine at pH 7.5, 6.5, and 5.5 decreased NH3 emissions linearly by 19, 33, and 36%, respectively, compared with the manure from unacidified urine. An animal study was conducted with 27 mid-lactation Holstein cows in a randomized complete block design. Cows were blocked by parity and days in milk and assigned to 1 of 3 different DCAD diets: (1) HDCAD, a diet with DCAD of 193 mEq/kg of dry matter (DM); (2) MDCAD, a diet with 101 mEq/kg of DM; and (3) LDCAD, a diet with 1 mEq/kg of DM. A commercial anionic product (predominantly ammonium chloride) partly replaced urea, soybean meal, soyhulls, and corn grain in MDCAD and LDCAD to lower DCAD. The experiment lasted 7 wk (1-wk covariate followed by 6-wk data collection). Spot urine and fecal samples were collected for manure incubation. Data were analyzed using the MIXED procedure of SAS in a randomized block design. Dry matter intake and milk yield were not altered by treatments. No difference in milk fat content was observed among treatments, but fat yield tended to decrease linearly (1.00 to 0.86 kg/d) as DCAD decreased, resulting in a tendency for decreasing energy-corrected milk yield (35.1 to 32.7 kg/d). Milk protein content increased (3.00 to 3.14%) as DCAD decreased, but milk protein yield was not affected. Total-tract digestibility of DM, organic matter, and neutral detergent fiber did not differ among treatments. Digestibility of crude protein tended to decrease as DCAD decreased. There was no difference in fecal and urine N excretion among treatments, but fecal N as proportion of N intake tended to increase as DCAD decreased. Urine pH decreased linearly from 8.42 for HDCAD to 8.11 and 6.41 for MDCAD and LDCAD, respectively, resulting in decreased manure pH (7.57, 7.40, and 6.96 for HDCAD, MDCAD, and LDCAD, respectively). The cumulative NH3 emissions from manures over 6 d tended to decrease linearly as DCAD decreased (461 to 390 mg/kg of manure), but the decrease was only numerical when calculated on a cow basis (i.e., g/cow). In conclusion, lowering DCAD has potential to reduce NH3 emission from manure of lactating cows. However, a tendency for decreased milk fat yield and energy-corrected milk yield suggests that DCAD of 1 mEq/kg of DM may be too low, and more studies are needed to examine relatively less reduced DCAD to determine production responses in addition to NH3 emission from manure.

Effects of diet fermentability and supplementation of 2-hydroxy-4-(methylthio)-butanoic acid and isoacids on milk fat depression: 2. Ruminal fermentation, fatty acid, and bacterial community structure.

The experiment was conducted to understand ruminal effects of diet modification during moderate milk fat depression (MFD) and ruminal effects of 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and isoacids on alleviating MFD. Five ruminally cannulated cows were used in a 5 × 5 Latin square design with the following 5 dietary treatments (dry matter basis): a high-forage and low-starch control diet with 1.5% safflower oil (HF-C); a low-forage and high-starch control diet with 1.5% safflower oil (LF-C); the LF-C diet supplemented with HMTBa (0.11%; 28 g/d; LF-HMTBa); the LF-C diet supplemented with isoacids [(IA) 0.24%; 60 g/d; LF-IA]; and the LF-C diet supplemented with HMTBa and IA (LF-COMB). The experiment consisted of 5 periods with 21 d per period (14-d diet adaptation and 7-d sampling). Ruminal samples were collected to determine fermentation characteristics (0, 1, 3, and 6 h after feeding), long-chain fatty acid (FA) profile (6 h after feeding), and bacterial community structure by analyzing 16S gene amplicon sequences (3 h after feeding). Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) in a Latin square design. Preplanned comparisons between HF-C and LF-C were conducted, and the main effects of HMTBa and IA and their interaction within the LF diets were examined. The LF-C diet decreased ruminal pH and the ratio of acetate to propionate, with no major changes detected in ruminal FA profile compared with HF-C. The α-diversity for LF-C was lower compared with HF-C, and ß-diversity also differed between LF-C and HF-C. The relative abundance of bacterial phyla and genera associated indirectly with fiber degradation was influenced by LF-C versus HF-C. As the main effect of HMTBa within the LF diets, HMTBa increased the ratio of acetate to propionate and butyrate molar proportion. Ruminal saturated FA were increased and unsaturated FA concentration were decreased by HMTBa, with minimal changes detected in ruminal bacterial diversity and community. As the main effect of IA, IA supplementation increased ruminal concentration of all branched-chain volatile FA and valerate and increased the percentage of trans-10 C18 isomers in total FA. In addition, α-diversity and the number of functional features were increased for IA. Changes in the abundances of bacterial phyla and genera were minimal for IA. Interactions between HMTBa and IA were observed for ruminal variables and some bacterial taxa abundances. In conclusion, increasing diet fermentability (LF-C vs. HF-C) influenced rumen fermentation and bacterial community structure without major changes in FA profile. Supplementation of HMTBa increased biohydrogenation capacity, and supplemental IA increased bacterial diversity, possibly alleviating MFD. The combination of HMTBa and IA had no associative effects in the rumen and need further studies to understand the interactive mechanism.

Effects of diet fermentability and supplementation of 2-hydroxy-4-(methylthio)-butanoic acid and isoacids on milk fat depression: 1. Production, milk fatty acid profile, and nutrient digestibility.

The objectives of this experiment were to determine the effects of increased diet fermentability and polyunsaturated fatty acids (FA) with or without supplemental 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa), isoacids (IA; isobutyrate, 2-methylbutyrate, isovalerate, and valerate) or the combination of these on milk fat depression (MFD). Ten Holstein cows (194 ± 58 DIM, 691 ± 69 kg BW, 28 ± 5 kg milk yield) were used in a replicated 5 × 5 Latin square design. Treatments included a high-forage control diet (HF-C), a low-forage control diet (LF-C) causing MFD by increasing starch and decreasing neutral detergent fiber (NDF), the LF-C diet supplemented with HMTBa at 0.11% (28 g/d), the LF-C diet supplemented with IA at 0.24% of dietary dry matter (60 g/d), and the LF-C diet supplemented with HMTBa and IA. Preplanned contrasts were used to compare HF-C versus LF-C and to examine the main effects of HMTBa or IA and their interactions within the LF diets. Dry matter intake was greater for LF-C versus HF-C, but milk yield remained unchanged. The LF-C diet decreased milk fat yield (0.87 vs. 0.98 kg/d) but increased protein yield compared with HF-C. As a result, energy-corrected milk was lower (28.5 vs. 29.6 kg/d) for LF-C versus HF-C. Although the concentration of total de novo synthesized FA in milk fat was not affected, some short- and medium-chain FA were lower for LF-C versus HF-C, but the concentrations of C18 trans-10 isomers were not different. Total-tract NDF apparent digestibility was numerically lower (42.4 vs. 45.6%) for LF-C versus HF-C. As the main effects, the decrease in milk fat yield observed in LF-C was alleviated by supplementation of HMTBa through increasing milk yield without altering milk fat content and by IA through increasing milk fat content without altering milk yield so that HMTBa or IA, as the main effects, increased milk fat yield within the LF diets. However, interactions for milk fat yield and ECM were observed between HMTBa and IA, suggesting no additive effect when used in combination. Minimal changes were found on milk FA profile when HMTBa was provided. However, de novo synthesized FA increased for IA supplementation. We detected no main effect of HMTBa, IA, and interaction between those on total-tract NDF digestibility. In conclusion, the addition of HMTBa and IA to a low-forage and high-starch diet alleviated moderate MFD. Although the mechanism by which MFD was alleviated was different between HMTBa and IA, no additive effects of the combination were observed on milk fat yield and ECM.

Effects of lysophospholipids on short-term production, nitrogen utilization, and rumen fermentation and bacterial population in lactating dairy cows.

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.