Altering the ratio of dietary C16:0 and cis-9 C18:1 interacts with production level in dairy cows: Effects on production responses and energy partitioning

Effects of including a palmitic acid-enriched supplement in low and high starch diets on milk production and energy partitioning of primiparous and multiparous dairy cows between mid and late-lactation

The aim of our study was to assess the effects of low or high-starch diets with or without palmitic acid (C16:0) supplementation on the yield of milk, milk components, and energy partitioning of primiparous and multiparous dairy cows between mid and late-lactation. Thirty-two Holstein cows, 12 primiparous ([mean ± SD] 163 ± 33 d in milk) and 20 multiparous ([mean ± SD] 179 ± 37 d in milk), were used in a split-plot Latin square design. Parity was considered the main plot, and within each plot, treatments were then randomly assigned in a replicated 4 × 4 Latin square with 21 d periods and balanced for carryover effects. Treatments were in a 2 × 2 factorial arrangement of dietary starch level and fatty acid (FA) supplementation as main factors. The starch factor comprised either low (LS; 16% of diet dry matter [DM]) or high (HS; 32% of diet DM) dietary starch. Dietary starch was altered by varying the proportion of ground corn, whole cottonseed, and soyhulls, with LS and HS diets containing ∼15 and 18% forage neutral detergent fiber (fNDF) and ∼37 and 25% neutral detergent fiber (NDF), respectively. The FA supplementation factor consisted of either control with no FA supplementation (CON) or a C16:0-enriched supplement at 1.5% of diet DM replacing soyhulls (PALM). Compared with LS, HS increased plasma insulin (0.20 μg/L) and energy partitioning to body reserves (2.04 percentage-units), tended to increase body condition score (BCS) and body weight (BW) change, and decreased dry matter intake (DMI; 1.10 kg/d), milk fat yield (0.04 kg/d) and milk urea nitrogen (MUN; 2.10 mg/dL). Compared with CON, PALM increased energy output to milk (1.10 Mcal/d), the yields of milk fat (0.10 kg/d), 3.5% fat-corrected milk (FCM; 1.90 kg/d) and energy corrected milk (ECM; 1.60 kg/d), and had no effect on BW-related variables. We observed a 3-way interaction between parity, starch, and FA supplementation affecting multiparous but not primiparous cows, where PALM increased plasma insulin concentration (0.14 μg/L) in LS but had the opposite effect in HS by tending to decrease insulin. Our results demonstrate important interactions between parity, starch levels, and FA supplementation. Overall, feeding a low-starch diet to mid and late-lactation dairy cows helped prevent excessive body condition and weight gain while increasing milk fat yield compared with a high-starch diet. Multiparous cows may benefit the most from a low-starch diet as multiparous cows seemed more prone to accumulating body reserves. Feeding a C16:0-enriched supplement increased milk fat yield and ECM without increasing weight gain, regardless of starch level or parity.

Effects of abomasal infusion of soybean or sunflower lecithin on nutrient digestibility and milk production in lactating dairy cows

The fatty acid (FA) and phospholipid composition of dietary lecithin may influence FA digestibility and milk production in cattle. Eight multiparous Holstein cows (99.4 ± 9.2 DIM; 48.9 ± 3.8 kg of milk/d) were enrolled in a 3 × 3 incomplete Latin square design with 3 treatments provided as continuous abomasal infusates spanning 14-d experimental periods: water (CON), soybean lecithin (SBL; 74.5 g of deoiled soy lecithin), or sunflower lecithin (SFL; 133.5 g of hydrolyzed sunflower lecithin). Cows were fed the same diet, which contained (% DM) 27.0% NDF, 15.6% CP, 26.2% starch, and 5.87% FA. Treatments did not modify BW, milk fat, protein, or lactose contents, or the efficiency of producing ECM. Cows infused with SFL had greater milk yields than those receiving SBL or CON treatments. Cows infused with SFL had higher total solids, protein, and lactose yields than cows receiving the SBL or CON treatments. Sunflower lecithin enhanced feed efficiency (milk yield/DMI) relative to SBL or CON. Treatment did not affect intakes or apparent total-tract digestibilities for NDF, CP, starch, or 16-carbon (16C) FA. Cows receiving SFL had greater total FA and 18-carbon (18C) FA intakes than SBL or CON, but treatments did not affect their digestibility. Milk FA composition was modified by treatment. Cows receiving SFL had a greater concentration of PUFA and lower concentrations of SFA and MUFA in milk relative to SBL or CON. In conclusion, the abomasal infusion of SFL improved milk production and milk FA composition, indicating potential benefits for dairy cow nutrition and milk quality.

Effects of raw and roasted high oleic soybeans on milk production of high-producing dairy cows

Processing method of soybeans has the potential to influence dairy cow production performance, therefore we determined the effect feeding raw or roasted, ground high oleic acid soybeans (HOSB) on production responses of high-producing dairy cows. Thirty-six multiparous Holstein cows (45.6 ± 6.22 kg/d of milk; 110 ± 61 DIM) were randomly assigned to treatment sequences in a 4 × 2 Truncated Latin square design with 35-d periods. Treatments were: 1) control diet containing soybean meal and soybean hulls (CON), 2) 16% roasted and ground HOSB (RST), 3) 16% raw and ground HOSB (RAW-D), and 4) 16% raw and ground HOSB + additional rumen by-pass protein (RAW-U). High oleic acid soybeans replaced conventional soybean meal and hulls in the control diet and rumen by-pass protein replaced soybean meal in RAW-U to maintain diet nutrient composition (%DM) of ∼28.0% NDF, 21.3% forage NDF, 27.3% starch, and 17.8% CP. Fatty acid content of CON, RST, RAW-D, and RAW-U was 1.60, 4.30, 4.36, and 4.34%DM, respectively. Pre-planned contrasts included the overall effect of HOSB inclusion {CON vs. HOSOY [1/3 (RST + RAW-D + RAW-U)]}, the effect of soybean processing {RST vs. RAW [1/2 (RAW-D + RAW-U)]}, and the effect of increasing RUP content within the raw HOSB treatments (RAW-D vs RAW-U). For most variables tested, there were significant interactions between treatment and week, as HOSOY increased production variables compared with CON and RST increased production responses compared with RAW, with only the magnitude of difference varying between weeks. Overall, HOSOY increased DMI and yields of milk, 3.5% FCM, ECM, and milk fat, but did not affect milk protein yield. RST did not impact DMI but increased yields of milk, 3.5% FCM, ECM, milk fat, and milk protein. Compared with RAW-D, RAW-U increased yields of milk and milk protein and tended to increase ECM. Overall, HOSB inclusion of 16% DM increased production responses in high-producing dairy cows, but roasted HOSB had a greater impact than raw HOSB, and the addition of rumen-bypass protein positively affected milk protein response.

Effects of the palmitic-to-oleic ratio in the form of calcium salts of fatty acids on the production and digestibility in high-yielding dairy cows

The form of fat supplements, degree of saturation, and the fatty acid (FA) profile influence cows' production response. The objective was to determine the effects of supplemental fats in the form of calcium salts (CS) of FA (CSFA) with different ratios between palmitic (PA) and oleic (OA) acids on nutrient digestibility and cow performance. Forty-two dairy cows were assigned to 3 groups and fed (for 13 wk) rations that contained 2.2% CSFA (on a DM basis) with increasing PA-to-OA ratios as follows: (1) CS45:35, 45% PA and 35% OA; (2) CS60:30, 60% PA and 30% OA; and (3) CS70:20, 70% PA and 20% OA. Rumen and fecal samples were taken for VFA and digestibility measurements, respectively. Increasing the PA-to-OA ratio linearly decreased the milk and ECM yields, whereas a quadratic effect was observed for milk fat concentration (3.55%, 3.94%, and 3.87% in the CS45:35, CS60:30, and CS70:20 groups, respectively) and fat yield. Dry matter intake was highest in the CS60:30 group (33.7 kg/d) and lowest in the CS70:20 group (31.6 kg/d), and a tendency of quadratic effect was observed for calculated energy balance with no difference in BW gain among the groups. The milk-to-DMI ratio was decreased, and the ratio of ECM-to-DMI tended to decrease when the PA-to-OA ratio increased. The highest apparent total-tract digestibilities of DM, OM, and protein were observed in the CS60:30 cows, and NDF tended to decrease with increasing PA-to-OA ratio; however, digestibility of the total FA and FA subgroups (16- and 18-carbon FA) were not different among groups. Across treatments, the 18-carbon FA digestibility was higher than the 16-carbon FA digestibility. Under the current study conditions, the CS60:30 cows had the highest fat concentration and fat yield; energy output in milk; DMI; and digestibility of DM, OM, and protein. However, further research is required to fine tune the optimal FA ratio in supplemental fat sources to maximize production and efficiency under various conditions, such as production level, stage of lactation, and diet composition.

Effects of altering the ratio of C16:0 and cis-9 C18:1 in rumen bypass fat on growth performance, lipid metabolism, intestinal barrier, cecal microbiota, and inflammation in fattening bulls

BACKGROUND

C16:0 and cis-9 C18:1 may have different effects on animal growth and health due to unique metabolism in vivo. This study was investigated to explore the different effects of altering the ratio of C16:0 and cis-9 C18:1 in fat supplements on growth performance, lipid metabolism, intestinal barrier, cecal microbiota, and inflammation in fattening bulls. Thirty finishing Angus bulls (626 ± 69 kg, 21 ± 0.5 months) were divided into 3 treatments according to the randomized block design: (1) control diet without additional fat (CON), (2) CON + 2.5% palmitic acid calcium salt (PA, 90% C16:0), and (3) CON + 2.5% mixed fatty acid calcium salt (MA, 60% C16:0 + 30% cis-9 C18:1). The experiment lasted for 104 d, after which all the bulls were slaughtered and sampled for analysis.

RESULTS

MA tended to reduce 0-52 d dry matter intake compared to PA (DMI, P = 0.052). Compared with CON and MA, PA significantly increased 0-52 d average daily gain (ADG, P = 0.027). PA tended to improve the 0-52 d feed conversion rate compared with CON (FCR, P = 0.088). Both PA and MA had no significant effect on 52-104 days of DMI, ADG and FCR (P > 0.05). PA tended to improve plasma triglycerides compared with MA (P = 0.077), significantly increased plasma cholesterol (P = 0.002) and tended to improve subcutaneous adipose weight (P = 0.066) when compared with CON and MA. Both PA and MA increased visceral adipose weight compared with CON (P = 0.021). Only PA increased the colonization of Rikenellaceae, Ruminococcus and Proteobacteria in the cecum, and MA increased Akkermansia abundance (P < 0.05). Compared with CON, both PA and MA down-regulated the mRNA expression of Claudin-1 in the jejunum (P < 0.001), increased plasma diamine oxidase (DAO, P < 0.001) and lipopolysaccharide (LPS, P = 0.045). Compared with CON and MA, PA down-regulated the ZO-1 in the jejunum (P < 0.001) and increased plasma LPS-binding protein (LBP, P < 0.001). Compared with CON, only PA down-regulated the Occludin in the jejunum (P = 0.013). Compared with CON, PA and MA significantly up-regulated the expression of TLR-4 and NF-κB in the visceral adipose (P < 0.001) and increased plasma IL-6 (P < 0.001). Compared with CON, only PA up-regulated the TNF-α in the visceral adipose (P = 0.01). Compared with CON and MA, PA up-regulated IL-6 in the visceral adipose (P < 0.001), increased plasma TNF-α (P < 0.001), and reduced the IgG content in plasma (P = 0.035). Compared with CON, PA and MA increased C16:0 in subcutaneous fat and longissimus dorsi muscle (P < 0.05), while more C16:0 was also deposited by extension and desaturation into C18:0 and cis-9 C18:1. However, neither PA nor MA affected the content of cis-9 C18:1 in longissimus dorsi muscle compared with CON (P > 0.05).

CONCLUSIONS

MA containing 30% cis-9 C18:1 reduced the risk of high C16:0 dietary fat induced subcutaneous fat obesity, adipose tissue and systemic low-grade inflammation by accelerating fatty acid oxidative utilization, improving colonization of Akkermansia, reducing intestinal barrier damage, and down-regulating NF-κB activation.

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 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 (12 blocks total) 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 (PA)- or C18:0 (SA)-enriched fat, and with or without LPL. The experiment was conducted for 6 wk to measure daily dry matter intake, 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 the 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, the PA treatment 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 the PA and SA groups, 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, the PA diet 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.

High oleic soybean oil maintains milk fat and increases apparent total-tract fat digestibility and fat deposition in lactating dairy cows

Due to the bioactive properties of oleic acid, the objective of this study was to feed high oleic soybean oil (HOSO) to lactating cows and evaluate milk production, body composition, and apparent total-tract digestibility variables. Thirty Holstein cows (n = 16 primiparous, n = 14 multiparous at 87 ± 26 DIM at the start of the trial) were used in a crossover design with periods lasting 21 d. The treatments were a control (CON) diet with no added soybean oil and a HOSO diet with 1.5% diet DM of high oleic soybean oil. Dry matter and milk production data were collected the last 7 d of each period, and milk composition was collected the last 3 d of each period. Fecal samples were collected 6 times during the last 3 d of each period. Body weights were collected on the last 3 d of each period after the morning milking and ultrasound scans of the longissimus dorsi on the last day of each period. Compared with CON, HOSO did not affect DMI, milk production, and milk component yields. However, a parity effect was observed with multiparous cows having increased DMI (5.9 kg/d), milk production (11.2 kg/d), and component yields, with no treatment by parity interactions. Milk fat concentration tended to be greater for HOSO cows. Body weight data tended to have an interaction between treatment and parity, with multiparous HOSO cows having increased BW compared with CON and no effect on primiparous cows. Similar treatment by parity effects were observed for BCS. Compared with CON, HOSO increased fat depth by 0.44 mm and apparent total-tract fat digestibility by 12 percentage units. The results of this study indicated no detrimental effects of HOSO on milk production parameters with an increase in milk fat concentration, fat digestibility, and deposition compared with a control diet.

Effects of dietary palmitic acid and oleic acid ratio on milk production, nutrient digestibility, blood metabolites, and milk fatty acid profile of lactating dairy cows

Adequate energy supply is a crucial factor for maintaining the production performance in cows during the early lactation period. Adding fatty acids (FA) to diets can improve energy supply, and the effect could be related to the chain length and degree of saturation of those FA. This study was conducted to evaluate the effect of different ratios of palmitic acid (C16:0) to oleic acid (cis-9 C18:1) on the production performance, nutrient digestibility, blood metabolites, and milk FA profile in early lactation dairy cows. Seventy-two multiparous Holstein cows (63.5 ± 2.61 days in milk) blocked by parity (2.39 ± 0.20), body weight (668.3 ± 20.1 kg), body condition score (3.29 ± 0.06), and milk yield (47.9 ± 1.63 kg) were used in a completely randomized design. Cows were divided into 3 groups with 24 cows in each group. Cows in the 3 treatment groups were provided iso-energy and iso-nitrogen diets, but the C16:0 to cis-9 C18:1 ratios were different: (1) 90.9% C16:0 + 9.1% cis-9 C18:1 (90.9:9.1); (2) 79.5% C16:0 + 20.5% cis-9 C18:1 (79.5:20.5); and (3) 72.7% C16:0 + 27.3% cis-9 C18:1 (72.7:27.3). Fatty acids were added at 1.3% on a dry matter basis. Although the dry matter intake fat-corrected milk yield and energy-corrected milk yield were not affected, the milk yield, milk protein yield, and feed efficiency increased linearly with increasing cis-9 C18:1 ratio. The milk protein percentage and milk fat yield did not differ among treatments, whereas the milk fat percentage tended to decrease linearly with the increasing cis-9 C18:1 ratio. The lactose yield increased linearly and lactose percentage tended to increase linearly with increasing cis-9 C18:1 ratio, but the percentage of milk total solids and somatic cell count decreased linearly. Although body condition scores were not affected by treatments, body weight loss decreased linearly with increasing cis-9 C18:1 ratio. The effect of treatment on nutrient digestibility was limited, except for a linear increase in ether extract and neutral detergent fiber digestibility with increasing cis-9 C18:1 ratio. There was a linear increase in the concentration of plasma glucose, but the triglyceride and nonesterified FA concentrations decreased linearly with increasing cis-9 C18:1 ratio. As the cis-9 C18:1 ratio increased, the concentration of de novo FA decreased quadratically, but the mixed and preformed fatty acids increased linearly. In conclusion, increasing cis-9 C18:1 ratio could increase production performance and decrease body weight loss by increasing nutrient digestibility, and the ratio that had the most powerful beneficial effect on early lactation cows was 72.7:27.3 (C16:0 to cis-9 C18:1).

Effects of increasing dietary inclusion of high oleic acid soybeans on milk production of high-producing dairy cows

Recent research has highlighted the importance of dietary fatty acid profile of fatty acid supplements on production responses of high-producing dairy cows. Conventional soybeans contain ∼15% oleic acid and ∼50% linoleic acid whereas high oleic acid soybeans (HOSB) contain ∼70% oleic acid and ∼7% linoleic acid. We determined the effect of increasing dietary inclusion of roasted and ground HOSB on production responses of high-producing dairy cows. Twenty-four multiparous Holstein cows (50.7 ± 4.45 kg/d of milk; 122 ± 57 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were increasing doses of HOSB at 0, 8, 16, and 24% DM. The HOSB replaced conventional soybean meal and hulls to maintain similar diet nutrient composition (% DM) of 27.4 - 29.4% (NDF), 20.6% forage NDF, 27.5% starch, and 15.9 - 16.5% CP. Total fatty acid content of treatments was 1.65, 3.11, 4.52, and 5.97% DM, respectively. Pre-planned polynomial orthogonal contrasts included the linear, quadratic, and cubic effects of increasing HOSB. Increasing dietary inclusion of HOSB linearly decreased DMI and milk urea nitrogen and increased yields of milk, 3.5% fat corrected milk, energy corrected milk, and milk fat, and quadratically increased milk protein. The increased response to milk fat was due to an increase in preformed milk fatty acids. Due to the increase in milk component yields and decrease in DMI, there was an increase in feed efficiency. Increasing HOSB inclusion linearly decreased plasma BUN concentration and tended to decrease plasma insulin. Increasing HOSB had no effect on BW change or BCS change. In summary, increasing dietary inclusion of HOSB up to 24% DM increased production responses of high-producing dairy cows and did not affect body reserves.

Supply of palmitic, stearic, and oleic acid changes rumen fiber digestibility and microbial composition

The concept that fat supplementation impairs total-tract fiber digestibility in ruminants has been widely accepted over the past decades. Nevertheless, the recent interest in the dietary fatty acid profile to dairy cows enlightened the possible beneficial effect of specific fatty acids (e.g., palmitic, stearic, and oleic acids) on total-tract fiber digestibility. Because palmitic, stearic, and oleic acids are the main fatty acids present in ruminal bacterial cells, we hypothesize that the dietary supply of these fatty acids will favor their incorporation into the bacterial cell membranes, which will support the growth and enrichment of fiber-digesting bacteria in the rumen. Our objective in this experiment was to investigate how dietary supply of palmitic, stearic, and oleic acid affect fiber digestion, bacterial membrane fatty acid profile, microbial growth, and composition of the rumen bacterial community. Diets were randomly assigned to 8 single-flow continuous culture fermenters arranged in a replicated 4 × 4 Latin square with four 11-d experimental periods. Treatments were (1) a control basal diet without supplemental fatty acids (CON); (2) the control diet plus palmitic acid (PA); (3) the control diet plus stearic acid (SA); and (4) the control diet plus oleic acid (OA). All fatty acid treatments were included in the diet at 1.5% of the diet (dry matter [DM] basis). The basal diet contained 50% orchardgrass hay and 50% concentrate (DM basis) and was supplied at a rate of 60 g of DM/d in 2 equal daily offers (0800 and 1600 h). Data were analyzed using a mixed model considering treatments as fixed effect and period and fermenter as random effects. Our results indicate that PA increased in vitro fiber digestibility by 6 percentage units compared with the CON, while SA had no effect and OA decreased fiber digestibility by 8 percentage units. Oleic acid decreased protein expression of the enzymes acetyl-CoA carboxylase compared with CON and PA, while fatty acid synthase was reduced by PA, SA, and OA. We observed that PA, but not SA or OA, altered the bacterial community composition by enhancing bacterial groups responsible for fiber digestion. Although the dietary fatty acids did not affect the total lipid content and the phospholipid fraction in the bacterial cell, PA increased the flow of anteiso C13:0 and anteiso C15:0 in the phospholipidic membrane compared to the other treatments. In addition, OA increased the flow of C18:1 cis-9 and decreased C18:2 cis-9,cis-12 in the bacterial phospholipidic membranes compared to the other treatments. Palmitic acid tended to increase bacterial growth compared to other treatments, whereas SA and OA did not affect bacterial growth compared with CON. To our knowledge, this is the first research providing evidence that palmitic acid supports ruminal fiber digestion through shifts in bacterial fatty acid metabolism that result in changes in growth and abundance of fiber-degrading bacteria in the microbial community.

Increasing palmitic acid and reducing stearic acid content of supplemental fatty acid blends improves production performance of mid-lactation dairy cows

We determined the effects of altering the ratio of palmitic (C16:0) and stearic (C18:0) acids in supplemental fatty acid (FA) blends on production responses of mid-lactation dairy cows. Twenty-four multiparous Holstein cows (mean ± standard deviation; 47.1 ± 5.8 kg of milk yield, 109 ± 23 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were a control diet not supplemented with FA (CON), and 3 diets incorporating 1.5% of dry matter (DM) FA supplement blends containing 30% C16:0 + 50% C18:0, 50% C16:0 + 30% C18:0, and 80% C16:0 + 10% C18:0. Additionally, the FA blends were balanced to contain 10% of oleic acid (cis-9 C18:1). The FA blends replaced soyhulls in the CON diet. Diets were formulated to contain (% of DM) 31.0% neutral detergent fiber, 27.0% starch, and 16.9% crude protein. The statistical model included the random effect of cow within square and the fixed effects of period, treatment, and their interaction. Preplanned contrasts included CON versus overall effect of FA supplementation and the linear and quadratic effects of increasing C16:0 in FA blends. Overall FA treatment had no effect on dry matter intake (DMI), but increasing C16:0 linearly increased DMI. Compared with CON, overall FA treatment increased yields of milk, 3.5% of fat-corrected milk, energy-corrected milk, and milk fat but did not affect milk protein yield. Increasing C16:0 linearly increased milk fat yield and tended to linearly increase the yields of 3.5% of fat-corrected milk and energy-corrected milk. Fatty acid supplementation decreased the yield of de novo milk FA but increased yields of mixed and preformed milk FA compared with CON. Increasing C16:0 in FA treatments did not affect the yield of de novo milk FA, linearly increased the yield of mixed, and decreased the yield of preformed milk FA. In summary, feeding FA supplements containing C16:0 and C18:0 increased milk production responses with no effect on DMI compared with a control diet. Mid-lactation cows producing ∼40 to 50 kg/d milk yield responded best to increasing supplemental C16:0 in FA supplements, demonstrating that FA supplements higher in C16:0 and limited in C18:0 improves production responses.

Abomasal infusion of oleic acid and exogenous emulsifier alter fatty acid digestibility and production responses of lactating dairy cows

We evaluated the effects of abomasal infusion of cis-9 C18:1 (oleic acid) and an exogenous emulsifier (polysorbate-C18:1) on fatty acid (FA) digestibility and production responses of dairy cows. Eight rumen-cannulated multiparous cows (96 ± 23 d in milk) were assigned to a 2 × 2 factorial arrangement of treatments in 4 × 4 Latin squares with 18-d periods consisting of 7 d of washout and 11 d of infusion. Treatments were abomasal infusions of water carrier only (CON), 45 g/d oleic acid (OA), 20 g/d polysorbate-C18:1 (T80), or both 45 g/d OA and 20 g/d T80 (OA+T80). The OA treatments were dissolved in ethanol and the T80 treatments in water. To deliver the daily dose for each treatment, the infusate solution was divided into 4 equal infusions per day, occurring every 6 h. Cows were fed the same diet, which contained (% of dry matter [DM]) 30.3% neutral detergent fiber (NDF), 16.3% crude protein, 30% starch, and 3.2% FA (including 1.8% DM from a FA supplement containing 34.4% C16:0 and 47.7% C18:0). Infusion of T80 increased NDF digestibility compared with all other treatments (3.57 percentage units), whereas OA+T80 decreased NDF digestibility compared with CON (3.30 percentage units). Compared with CON, OA (4.90 percentage units) and T80 (3.40 percentage units) increased total FA digestibility, whereas OA+T80 had no effect on total FA digestibility. We did not observe differences between OA and T80 for total FA digestibility. Infusion of OA (3.90 percentage units) and T80 (2.80 percentage units) increased 16-carbon FA digestibility compared with CON. Digestibility of 16-carbon FA did not differ between OA and T80 or between CON and OA+T80. Compared with CON, OA increased (5.60 percentage units) and T80 tended to increase 18-carbon FA digestibility. Digestibility of 18-carbon FA did not differ between OA and T80 or between CON and OA+T80. Compared with CON, all treatments increased or tended to increase the absorption of total and 18-carbon FA. Infusion of OA and T80 increased the yields of milk fat (both increased 0.10 kg/d), 3.5% fat-corrected milk (1.90 and 2.50 kg/d), and energy-corrected milk (1.80 and 2.60 kg/d) compared with CON. We did not observe differences between OA and T80 or between CON and OA+T80 for yields of milk fat, 3.5% fat-corrected milk, or energy-corrected milk. Infusing OA tended to increase plasma insulin concentration compared with CON. Compared with the other treatments, OA+T80 decreased the yield of de novo milk FA (31.3 g/d). Compared with CON, OA tended to increase the yield of de novo milk FA. Compared with OA+T80, CON and OA tended to increase the yield of mixed milk FA, whereas T80 increased it (83 g/d). Compared with CON, all emulsifier treatments increased the yield of preformed milk FA (52.7 g/d). In conclusion, abomasally infusing either 45 g of OA or 20 g of T80 improved digestibility and similarly favored the production parameters of dairy cows. In contrast, providing both (45 g of OA + 20 g of T80) had no additional benefits and moderated the positive responses observed in the individual treatments with OA and T80.

Comparison of rumen and abomasal infusions of an exogenous emulsifier on fatty acid digestibility of lactating dairy cows

We evaluated the effects of infusing an exogenous emulsifier (polysorbates-C18:1) either into the rumen or abomasum on fatty acid (FA) digestibility and production responses of lactating dairy cows. Nine ruminally cannulated multiparous Holstein cows (170 ± 13.6 d in milk) were assigned to a treatment sequence in replicated 3 × 3 Latin squares with 18-d periods consisting of 7 d of washout and 11 d of infusion. Treatments were abomasal infusions of water carrier only into the rumen and abomasum (control, CON), 30 g/d polysorbate-C18:1 (T80) infused into the rumen (RUM), or 30 g/d T80 infused into the abomasum (ABO). Emulsifiers were dissolved in water and delivered at 6-h intervals (total daily infusion was divided into 4 equal infusions per day). Cows were fed the same diet that contained [% diet dry matter (DM)] 32.2% neutral detergent fiber (NDF), 16.1% crude protein, 26.5% starch, and 3.41% FA (including 1.96% FA from a saturated FA supplement containing 28.0% C16:0 and 54.6% C18:0). Two orthogonal contrasts were evaluated: (1) the overall effect of T80 {CON vs. average of the T80 infusions [1/2 (ABO + RUM)]}, and (2) the effect of ABO versus RUM infusion. Compared with CON, infusing T80 increased the digestibilities of NDF (2.85 percentage units), total (4.35 percentage units), 16-carbon (3.25 percentage units), and 18-carbon FA (4.60 percentage units), and tended to increase DM digestibility and total and 18-carbon FA absorption. Compared with RUM, ABO decreased the intakes of total (28 g/d), 16-carbon (7 g/d), and 18-carbon FA (19 g/d); tended to increase the digestibility of total and 18-carbon FA; and had no effect on the absorption of total, 16-carbon, or 18-carbon FA. Production responses did not change among our treatments. In conclusion, infusing 30 g/d polysorbates-C18:1 increased NDF and total, 16-carbon, and 18-carbon FA digestibility. Compared with RUM, ABO tended to increase the digestibilities of total and 18-carbon FA; however, this may be related to the fact that ABO reduced the intakes of total, 16-carbon, and 18-carbon FA, not necessarily due to better emulsifying action per se. In summary, ABO and RUM both improved FA absorption.

Oleic acid abomasal infusion limits lipolysis and improves insulin sensitivity in adipose tissue from periparturient dairy cows

Excessive adipose tissue (AT) lipolysis around parturition in dairy cows is associated with impaired AT insulin sensitivity and increased incidence of metabolic diseases. Supplementing cows with oleic acid (OA) reduces circulating biomarkers of lipolysis and improves energy balance. Nevertheless, it is unclear if OA alters lipid trafficking in AT. In the liver and skeletal muscle, OA improves mitochondrial function and promotes lipid droplet formation by activating perilipin 5 (PLIN5) and peroxisome proliferator-activated receptor α (PPARα). However, it is unknown if this mechanism occurs in AT. The objective of this study was to determine the effect of OA on AT lipolysis, systemic and AT insulin sensitivity, and AT mitochondrial function in periparturient dairy cows. Twelve rumen-cannulated Holstein cows were infused abomasally following parturition with ethanol (CON) or OA (60 g/d) for 14 d. Subcutaneous AT samples were collected at 11 ± 3.6 d before calving (-12 d), and 6 ± 1.0 d (7 d) and 13 ± 1.4 d (14 d) after parturition. An intravenous glucose tolerance test was performed on d 14. Adipocyte morphometry was performed on hematoxylin and eosin-stained AT sections. The antilipolytic effect of insulin (1 μg/L) was evaluated using an ex vivo explant culture following lipolysis stimulation. PLIN5 and PPARα transcription and translation were determined by real-time quantitative PCR and capillary electrophoresis, respectively. RNA sequencing was used to evaluate the transcriptomic profile of mitochondrial gene networks. In CON cows, postpartum lipolysis increased the percentage of smaller (<3,000 µm²) adipocytes at 14 d compared with -12 d. However, OA limited adipocyte size reduction at 14 d. Likewise, OA decreased lipolysis plasma markers nonesterified free fatty acids and β-hydroxybutyrate at 5 and 7 d. Over the 14-d period, compared with CON, OA increased the concentration of plasma insulin and decreased plasma glucose. During the glucose tolerance test, OA decreased circulating glucose concentration (at 10, 20, 30, 40 min) and the glucose clearance rate. Moreover, OA increased insulin at 10 and 20 min and tended to increase it at 30 min. Following lipolysis stimulation, OA improved the antilipolytic effect of insulin in the AT at 14 d. PLIN5 and PPARA gene expression decreased postpartum regardless of treatment. However, OA increased PLIN5 protein expression at 14 d and increased PPARA at 7 and 14 d. Immunohistochemical analysis of AT and RNA sequencing data showed that OA increased the number of mitochondria and improved mitochondrial function. However, OA had no effect on production and digestibility. Our results demonstrate that OA limits AT lipolysis, improves systemic and AT insulin sensitivity, and is associated with markers of mitochondrial function supporting a shift to lipogenesis in AT of periparturient dairy cows.

The form more than the fatty acid profile of fat supplements influences digestibility but not necessarily the production performance of dairy cows

The form of a lipid supplement, its degree of saturation, and its fatty acid (FA) profile greatly influence digestibility and cow productive response. The objective in this study was to examine the effect of fat supplements that differ in their form or FA profile on nutrient digestibility and cow performance. Forty-two mid-lactation cows (128 ± 53 d) were assigned to 3 treatment groups according to milk yield, days in milk, and body weight. For 13 wk, the cows were fed rations that contained (on a dry matter basis) (1) 2.4% of calcium salts of fatty acids (CSFA) consisting of 45% palmitic acid (PA) and 35% oleic acid (OA; CS45:35); (2) 2.4% of CSFA consisting of 80% PA and 10% OA (CS80:10); or (3) 2.0% of free FA consisting of 80% PA and 10% OA (FF80:10). Rumen samples were taken to measure the ammonia and volatile FA concentrations, and fecal samples were taken to measure the digestibility. Preplanned comparisons were CS45:35 versus CS80:10 to assess 2 CSFA supplements with different FA profiles, and CS80:10 versus FF80:10 to assess similar FA profiles in different forms. Compared with CS45:35, CS80:10 decreased the milk yields, increased the fat percentage, and tended to increase the energy-corrected milk (ECM) yields. The fat percentage of milk was highest in the FF80:10 cows (4.02%), intermediate in the CS80:10 cows (3.89%), and lowest in the CS45:35 cows (3.75%). Compared with CS80:10, FF80:10 increased milk yields (50.1 vs. 49.4 kg/d, respectively), tended to increase fat percentage, and increased 4% fat-corrected milk (4% FCM; 49.1 vs. 47.7 kg/d, respectively) and ECM yields (49.5 vs. 48.2 kg/d, respectively). Treatment had no effect on dry matter intake (DMI), and compared with CS80:10 cows, the calculated energy balance was lower in the FF80:10 cows. The 4% FCM/DMI and ECM/DMI ratios were higher in the FF80:10 group compared with the CS80:10 group. Compared with the CS80:10 cows, the FF80:10 cows had a lower rumen pH, higher propionate, lower acetate/propionate ratio, and higher total VFA. Compared with CS45:35 cows, the apparent total-tract digestibilities of neutral detergent fiber and acid detergent fiber were higher in CS80:10 cows; whereas, the apparent total-tract digestibilities of dry matter, organic matter, protein, neutral detergent fiber, and acid detergent fiber were higher in the CS80:10 cows compared with the FF80:10 cows. Compared with the CS80:10 group, the apparent digestibility of total FA was 13.0 percentage points lower in the FF80:10 cows (79.1 vs. 66.1%, respectively), and similarly, the digestibilities of 16-carbon and 18-carbon FA were lower in the FF80:10 cows than in the CS80:10 cows. In conclusion, the form, more than the FA profile of fat supplements, influenced digestibility. Further, the CSFA supplements were more digestible than the free fatty acids, regardless of the FA profile. However, energy partitioning toward production appeared to be higher in the FF80:10 cows, although the digestibility of nutrients was lower than in the CSFA product with a similar FA profile.

Relationships among total mixed ration nutritional components and reproductive performance in high-producing dairy herds

The main objective of the present study was to determine whether composition of total mixed ration influences reproductive performance in high-producing commercial dairy farms. Dairy producers and nutritional consultants from 48 dairy farms located in Wisconsin agreed to provide reproductive data and dietary information on high milk production pens during the main breeding period for the previous 12 mo. Dietary components (percentage of dry matter) were crude protein (CP), rumen degradable (RDP) and undegradable (RUP) protein, neutral detergent fiber (NDF), nonfiber carbohydrates (NFC), starch, and fat. Reproductive data were service rate (SR), overall pregnancy per artificial insemination (P/AI) and P/AI at the first service, 21-d pregnancy rate (PR), days open, and percentage of cows pregnant by 150 d in milk (PREG150). Participating herds had lactating Holstein cows (range = 143 to 2,717) housed in freestall facilities. Statistical analyses were performed with CORR and GLIMMIX of SAS (SAS Institute Inc.). Daily average milk production of herds was 38.9 ± 0.60 kg/d (30.0 to 50.4 kg/d). Overall SR was 58.5% (39-73) and P/AI was 36.1% (22-49). Overall 21-d PR was 20.3% (10-42%). Correlation between SR and PR was 0.59, whereas correlation of overall P/AI and P/AI at first service with PR were both 0.72. Similarly, for PREG150, correlation with overall P/AI (0.63) and P/AI at first service (0.66) were greater than with SR (0.48). There was large variation in diet composition, with CP varying from 16.0 to 18.7%, NDF from 24.9 to 35.1%, NFC from 31.7 to 46.6%, starch from 20.1 to 30.8%, and fat from 3.1 to 6.7%. Overall, there were no detectable associations of CP, RDP, and RUP with reproductive measures. The strongest relationship was a decrease in reproductive performance with increasing dietary NFC including overall P/AI (-0.48), P/AI at first service (-0.51), and PREG150 (-0.33). Starch also had a negative relationship with P/AI at first service (-0.35). Conversely, greater NDF was positively associated with P/AI at first service (0.34). Fat content was also positively associated with P/AI at first service (0.34). When NFC was divided in tertiles (<40, 40 to 42.2, and >42.2% NFC), the highest tertile had lower overall P/AI (39 vs. 36 vs. 31%), P/AI at first service (43 vs. 40 vs. 33%), and PREG150 (54 vs. 53 vs. 47%). In conclusion, farms with greater dietary NFC may have compromised reproductive performance. Correspondingly, herds with greater NDF content may achieve high milk production with potentially positive associations with reproduction. Other relationships of dietary components on reproduction were not as obvious in this herd-level analysis.

Abomasal infusion of different exogenous emulsifiers alters fatty acid digestibility and milk fat yield of lactating dairy cows

We evaluated the effects of abomasal infusion of emulsifiers on fatty acid (FA) digestibility and milk production of lactating dairy cows. All emulsifiers examined were polysorbates, nonionic surfactants, consisting of a polyethoxylated sorbitan esterified with FA. The polysorbates tested in this study consisted of the same polyethoxylated sorbitan base but differed by the FA esterified to it. Eight rumen-cannulated multiparous cows (89 ± 13 d in milk) were assigned to a treatment sequence in 4 × 4 Latin squares with 18-d periods consisting of 7 d of washout and 11 d of infusion. Treatments were abomasal infusions of water only (CON) or 30 g/d of different emulsifiers as follows: polysorbate-C16:0 (T40), polysorbate-C18:0+C16:0 (T60), and polysorbate-C18:1 (T80). Emulsifiers were dissolved in water and delivered at 6-h intervals (total daily infusion was divided into 4 equal infusions per day). Cows were fed the same diet that contained (% diet dry matter) 32.1% neutral detergent fiber, 15.7% crude protein, 25.8% starch, and 3.32% FA (including 1.92% FA from a saturated FA supplement containing 34.2% C16:0 and 47.7% C18:0). The T80 treatment increased total FA digestibility compared with CON (5.40 percentage units) and T60 (3.90 percentage units) and tended to increase it compared with T40. Also, T40 tended to increase and T80 increased (4.80 percentage units) 16-carbon FA digestibility compared with CON. The T80 treatment increased 18-carbon FA digestibility compared with the other treatments. The T40 treatment tended to increase and T80 increased total FA absorption compared with CON (53 g/d) and T60 (52 g/d). Both T40 and T80 increased the absorption of 16-carbon FA compared with CON and T60. The T60 treatment did not differ from CON for any digestibility variable. Both T40 and T80 increased the yields of milk fat, 3.5% fat-corrected milk, and de novo, mixed, and preformed milk FA compared with CON. In conclusion, not all emulsifiers increased FA digestibility. Compared with CON, T80 increased the digestibility and absorption of total, 16-, and 18-carbon FA. The T40 treatment tended to increase and T80 increased total FA absorption and the yields of milk fat and 3.5% FCM compared with CON. Milk fat yield was increased by increases in de novo, mixed, and preformed milk FA. In our short-term infusion study, results suggest that the predominant FA present in the polysorbate affects its ability to improve FA digestibility. Overall, FA digestibility and absorption were improved the most when cows received the T80 treatment.

Abomasal infusion of oleic acid increases fatty acid digestibility and plasma insulin of lactating dairy cows

Our objective was to determine whether abomasal infusions of increasing doses of oleic acid (cis-9 C18:1; OA) improved fatty acid (FA) digestibility and milk production of lactating dairy cows. Eight rumen-cannulated multiparous Holstein cows (138 d in milk ± 52) were randomly assigned to treatment sequence in a replicated 4 × 4 Latin square design with 18-d periods consisting of 7 d of washout and 11 d of infusion. Production and digestibility data were collected during the last 4 d of each infusion period. Treatments were 0, 20, 40, or 60 g/d of OA. We dissolved OA in ethanol before infusions. The infusate solution was divided into 4 equal infusions per day, occurring every 6 h, delivering the daily cis-9 C18:1 for each treatment. Animals received the same diet throughout the study, which contained (percent diet dry matter) 28% neutral detergent fiber, 17% crude protein, 27% starch, and 3.3% FA (including 1.8% FA from a saturated FA supplement containing 32% C16:0 and 52% C18:0). Infusion of OA did not affect intake or digestibility of dry matter and neutral detergent fiber. Increasing OA from 0 to 60 g/d linearly increased the digestibility of total FA (8.40 percentage units), 16-carbon FA (8.30 percentage units), and 18-carbon FA (8.60 percentage units). Therefore, increasing OA linearly increased absorbed total FA (162 g/d), 16-carbon FA (26.0 g/d), and 18-carbon FA (127 g/d). Increasing OA linearly increased milk yield (4.30 kg/d), milk fat yield (0.10 kg/d), milk lactose yield (0.22 kg/d), 3.5% fat-corrected milk (3.90 kg/d), and energy-corrected milk (3.70 kg/d) and tended to increase milk protein yield. Increasing OA did not affect the yield of mixed milk FA but increased yield of preformed milk FA (65.0 g/d) and tended to increase the yield of de novo milk FA. Increasing OA quadratically increased plasma insulin concentration with an increase of 0.18 μg/L at 40 g/d OA, and linearly increased the content of cis-9 C18:1 in plasma triglycerides by 2.82 g/100 g. In conclusion, OA infusion increased FA digestibility and absorption, milk fat yield, and circulating insulin without negatively affecting dry matter intake. In our short-term infusion study, most of the digestion and production measurements responded linearly, indicating that 60 g/d OA was the best dose. Because a quadratic response was not observed, improvements in FA digestibility and production might continue with higher doses of OA, which deserves further attention.

Dietary fatty acid and starch content and supplemental lysine supply affect energy and nitrogen utilization in lactating Jersey cows

The effects of dietary fatty acid (FA) and starch content as well as supplemental digestible Lys (sdLys) on production, energy utilization, and N utilization were evaluated. Each factor was fed at 5 different amounts, and factor limits were as follows: 3.0 to 6.2% of dry matter (DM) for FA; 20.2 to 31.3% of DM for starch, and 0 to 17.8 g/d of sdLys. Dietary FA and starch were increased by replacing soyhulls with supplemental fat and corn grain, respectively, and sdLys increased with rumen-protected Lys. Fifteen unique treatments were fed to 25 Jersey cows (mean ± SD; 80 ± 14 d in milk) across 3 blocks in a partially balanced incomplete block design. Each block consisted of 4 periods of 28 d, where the final 4 d were used to determine milk production and composition, feed intake, energy utilization (via total collection and headbox-style indirect calorimetry), and N utilization (via total collection). Response surface models were used to evaluate treatment responses. Increasing dietary FA decreased DM intake and milk protein yield. When dietary starch was less than 24%, milk protein concentration increased with increasing sdLys, but when dietary starch was greater than 26% milk protein concentration decreased with increasing sdLys. Digestibility of FA increased when dietary FA increased from 3.0 to 4.2% and decreased as FA increased beyond 4.2%. Although neutral detergent fiber digestibility decreased as dietary starch increased, energy digestibility increased. As dietary FA increased, metabolizable energy (ME) content quadratically increased. Supply of ME increased as dietary FA increased from 3.0 to 4.2% and decreased as FA increased beyond 4.2%. Increasing dietary FA and starch decreased CH₄ production and urinary energy. Increasing dietary starch increased the efficiency of utilizing dietary N for milk N. Increasing sdLys quadratically decreased N balance as sdLys increased from 0 to 8 g/d and increased N balance as sdLys increased from 8 to 18 g/d. Increasing dietary FA can increase ME content, however, at high dietary FA, decreased DM intake and FA digestibility resulted in a plateau in ME content and a decrease in ME supply. Our results demonstrate that sdLys supply is important for milk protein when dietary starch is low, and some Lys may be preferentially used for muscle protein synthesis at the expense of milk protein when sdLys is high.

Effect of concentrate enriched with palmitic acid versus rapeseed oil on dairy performance, milk fatty acid composition, and mammary lipogenic gene expression in mid-lactation Holstein cows

This study was performed to characterize the effect of a concentrate supplemented with free palmitic acid (4% on a DM basis; PA) or rapeseed oil (4% on a DM basis; RO) compared with a no-added-lipid control concentrate (CT) on the performance of dairy cows fed a corn silage-based diet over a 9-wk period. After a 3-wk pre-experimental period, 54 Holstein cows were randomly allocated to 3 experimental treatments to receive forage ad libitum with a fixed amount of CT, RO, or PA (8 kg/d for 2-yr-old primiparous; 10 kg/d for older cows). During the experiment, dry matter intake, milk yield and composition, fatty acid (FA) yields and FA profile, and feed efficiency were determined. At wk 9 of the experimental period, the mRNA levels of 10 genes involved in lipid metabolism in mammary tissue biopsy samples were measured. Compared with CT, RO and PA increased forage intake. Compared with CT, RO increased concentrate intake, the value being intermediate for PA. Compared with CT, RO increased milk yield (+2.0 kg/d) and decreased milk fat and protein content (-3.8 and -1.2 g/kg, respectively), whereas PA increased milk fat content (+4.1 g/kg). Compared with CT and RO treatments, PA increased milk fat yield (+179 g/d) and 3.5% fat-corrected milk and energy-corrected milk output (+2.8 and +2.3 kg/d, respectively), and thus improved feed efficiency (+7.3%). Compared with CT treatment, RO increased milk contents of the sum of >C16 FA, monounsaturated FA, polyunsaturated FA, trans FA, and n-3 FA, whereas PA decreased these FA contents (except n-3 FA) and also decreased n-6 FA. The variations in milk fat yield and content and FA secretion at wk 9 were not associated with modifications in mammary expression of 10 genes involved in major lipid pathways, except for the transcription factor PPARG1, which tended to be higher in PA versus RO treatment. This study demonstrated that PA improved milk fat yield and feed efficiency compared with RO and suggests that factors other than gene expression, such as substrate availability for mammary metabolism or other levels of regulation (transcriptional, posttranscriptional, translational or posttranslational), could play a key role in milk fat and FA responses to changes in diet composition in cows.

Effects of calcium salts of palm fatty acids on nutrient digestibility and production responses of lactating dairy cows: A meta-analysis and meta-regression

Our primary objective was to perform a meta-analysis and meta-regression to evaluate the effects of diets supplemented with calcium salts of palm fatty acids (CSPF) compared with nonfat supplemented control diets (CON) on nutrient digestibility and production responses of lactating dairy cows. Our secondary objective was to perform a meta-analysis to evaluate whether experimental design affects production responses to supplemental CSPF. The data set was formed from 33 peer-reviewed publications with CSPF supplemented at ≤3% diet dry matter. We analyzed the interaction between experimental design (continuous vs. change-over) and treatments (CON vs. CSPF) to evaluate whether experimental design affects responses to CSPF (Meta.1). Regardless of experimental design, we evaluated the effects of CSPF compared with CON on nutrient digestibility and production responses of lactating dairy cows by meta-analysis (Meta.2) and meta-regression (Meta.3) approaches. In Meta.1, there was no interaction between treatments and experimental design for any variable. In Meta.2, compared with CON, CSPF reduced dry matter intake [DMI, 0.56 ± 0.21 kg/d (±SE)] and milk protein content (0.05 ± 0.02 g/100 g), increased neutral detergent fiber (NDF) digestibility (1.60 ± 0.57 percentage units), the yields of milk (1.53 ± 0.56 kg/d), milk fat (0.04 ± 0.02 kg/d), and 3.5% fat corrected milk (FCM, 1.28 ± 0.60 kg/d), and improved feed efficiency [energy corrected milk (ECM)/DMI, 0.08 kg/kg ± 0.03]. There was no effect of treatment for milk protein yield, milk fat content, body weight, body weight change, or body condition score. Compared with CON, CSPF reduced the yield of de novo milk fatty acids (FA) and increased the yields of mixed and preformed milk FA. In Meta.3, we observed that each 1-percentage-unit increase of CSPF in diet dry matter reduced DMI, increased NDF digestibility, tended to increase FA digestibility, increased the yields of milk, milk fat, and 3.5% FCM, reduced the content of milk protein, reduced the yield of de novo milk FA, and increased the yields of mixed and preformed milk FA. In conclusion, our results indicate no reason for the restrictive use of change-over designs in CSPF supplementation studies or meta-analysis. Feeding CSPF increased NDF digestibility, tended to increase FA digestibility, and increased the yields of milk, milk fat, and 3.5% FCM. Additionally, CSPF increased milk fat yield by increasing the yields of mixed and preformed milk FA.

Replacing stearic acid with oleic acid in supplemental fat blends improves fatty acid digestibility of lactating dairy cows

The objective of our study was to determine the effects of altering the ratio of stearic (C18:0; SA) and oleic (cis-9 C18:1; OA) acids in supplemental fatty acid (FA) blends on FA digestibility and milk yield of dairy cows. Eight multiparous Holstein cows (mean ± SD; 157 ± 11.8 d in milk) were randomly assigned to treatment sequence in a replicated 4 × 4 Latin square design with 14-d periods. Digestibility and production data were collected during the last 4 d of each period. The treatments were an unsupplemented control diet (CON), and 3 diets incorporating FA supplement blends at 1.4% of diet dry matter (DM) containing (as a % of total FA) 50% SA and 10% OA, 40% SA and 20% OA, or 30% SA and 30% OA. The FA blends were balanced to contain 33% palmitic, 5% linoleic, and <0.5% linolenic acids. The FA supplements replaced soyhulls in the CON diet. Preplanned contrasts were as follows: (1) overall effect of FA treatments [CON vs. the average of the FA-supplemented diets; (50:10 + 40:20 + 30:30)/3], (2) the linear effect of OA inclusion in the supplemental FA blend, and (3) the quadratic effect of OA inclusion in the supplemental FA blend. There was no effect of treatment on DM intake, but the replacement of soyhulls in the FA treatments decreased neutral detergent fiber intake. Overall, compared with CON, FA treatments increased DM and neutral detergent fiber digestibility, and increasing OA within FA treatments quadratically increased digestibility of DM and neutral detergent fiber. Overall, FA treatments increased the intake of total, 16-carbon, and 18-carbon FA, decreased the digestibility of total and 18-carbon FA, but increased absorption of total, 16-carbon, and 18-carbon FA. Within FA treatments, increasing OA linearly increased the digestibility of total, 16-carbon, and 18-carbon FA, as well as the absorption of total, 16-carbon, and 18-carbon FA. Overall, FA treatments increased the yields of milk, energy-corrected milk, and milk fat, and tended to increase milk protein yield. Compared with CON, FA treatments had no effect on the yield of de novo milk FA and increased the yields of mixed and preformed milk FA. Within FA treatments, increasing OA did not affect the yields of milk or milk components, linearly decreased the yield of de novo FA, and quadratically affected the yield of mixed and preformed milk FA. Overall, FA treatments increased plasma nonesterified fatty acids but did not affect β-hydroxybutyrate or insulin. Within FA treatments, increasing OA quadratically affected plasma nonesterified fatty acids, and tended to linearly increase β-hydroxybutyrate and quadratically affect insulin. In conclusion, supplemental FA blends containing different ratios of SA and OA did not affect DM intake but increased the yields of milk and milk components. Supplemental FA blends also increased digestibility of DM and neutral detergent fiber and decreased digestibility of total and 18-carbon FA compared with CON. Although increasing OA within FA supplements did not alter milk production, increasing OA within FA supplements increased total, 16-carbon, and 18-carbon FA digestibility and FA absorption. Further research is required to determine longer term effects of SA and OA on nutrient digestion and partitioning and opportunities for maintaining or improving FA digestibility with increasing SA intake and availability in the small intestine.

Effect of palmitic acid-enriched supplements containing stearic or oleic acid on nutrient digestibility and milk production of low- and high-producing dairy cows

We evaluated the effects of fatty acid (FA) supplement blends containing 60% palmitic acid (C16:0) and either 30% stearic acid (C18:0) or 30% oleic acid (cis-9 C18:1) on nutrient digestibility and milk production of low- and high-producing dairy cows. Twenty-four multiparous Holstein cows [118 ± 44 d in milk (DIM)] were divided into 2 blocks by milk production and then randomly assigned to treatment sequence in four 3 × 3 Latin squares within production level, balanced for carryover effects in three consecutive 21-d periods. Cows were blocked by milk yield and assigned to 1 of 2 groups (n = 12 per group): (a) low group (42.5 ± 3.54 kg/d; 147 ± 42 DIM) and (b) high group (55.8 ± 3.04 kg/d; 101 ± 34 DIM). Commercially available fat supplements were combined to provide treatments that consisted of the following: (1) control (CON; diet with no supplemental FA), (2) FA supplement blend containing 60% C16:0 and 30% C18:0 (PA+SA), and (3) FA supplement blend containing 60% C16:0 and 30% cis-9 C18:1 (PA+OA) The FA blends were fed at 1.5% of dry matter (DM) and replaced soyhulls from CON. Preplanned contrasts were (1) overall effect of FA treatments [CON vs. the average of the FA treatments (FAT); 1/2 (PA+SA + PA+OA)], and (2) effect of FA supplement (PA+SA vs. PA+OA). Regardless of production level, overall FAT reduced DMI compared with CON. Also, regardless of level of milk production, PA+OA increased total-tract FA digestibility compared with PA+SA. Treatment by production level interactions were observed for neutral detergent fiber (NDF) digestibility, total FA intake, and the yields of 3.5% fat-corrected milk (FCM), energy-corrected milk (ECM), and milk fat. In low-producing cows, FAT increased DM and NDF digestibility compared with CON. In high-producing cows PA+SA increased DM and NDF digestibility compared with PA+OA. In low-producing cows, PA+SA increased 3.5% FCM, ECM, and milk fat yield compared with PA+OA. However, in high-producing cows PA+OA tended to increase 3.5% FCM compared with PA+SA. In conclusion, low-producing cows responded better to a FA blend containing 60% C16:0 and 30% C18:0, whereas high-producing dairy cows responded more favorably to a FA blend containing 60% C16:0 and 30% cis-9 C18:1. However, further research is required to validate our observations that higher-yielding cows have improved production responses when supplemented with cis-9 C18:1 compared with C18:0.

Altering the ratio of dietary palmitic and oleic acids affects nutrient digestibility, metabolism, and energy balance during the immediate postpartum in dairy cows

This article is the second from an experiment that determined the effects of altering the dietary ratio of palmitic (C16:0) and oleic (cis-9 C18:1) acids on digestibility, production, and metabolic responses of dairy cows during the immediate postpartum. This article elaborates on the effect of these diets on nutrient digestibility, energy balance, and metabolism. Fifty-six multiparous cows were used in a randomized complete block design and randomly assigned to 1 of 4 treatments fed from 1 to 24 d in milk. The treatments were: (1) control (CON) diet not supplemented with fatty acids (FA); (2) diet supplemented with a FA blend containing 80% C16:0 and 10% cis-9 C18:1 (80:10); (3) diet supplemented with a FA blend containing 70% C16:0 and 20% cis-9 C18:1 (70:20); and (4) diet supplemented with a FA blend containing 60% C16:0 and 30% cis-9 C18:1 (60:30). The FA supplement blends were added at 1.5% of diet dry matter by replacing soyhulls in the CON diet. Three preplanned contrasts were used to compare treatment differences: (1) CON versus FA-supplemented diets, (80:10 + 70:20 + 60:30)/3; (2) the linear effect of cis-9 C18:1 inclusion in diets; and (3) the quadratic effect of cis-9 C18:1 inclusion in diets. The FA-supplemented diets increased digestibility of dry matter, neutral detergent fiber, 18-carbon FA, and total FA compared with CON. We observed a tendency for an interaction between treatment and time for the digestibility of 18-carbon and total FA because the difference in digestibility between CON and 60:30 treatments tended to increase over time. Increasing dietary cis-9 C18:1 increased linearly the digestibility of dry matter, neutral detergent fiber, 16-carbon, 18-carbon, and total FA. Interestingly, total absorbed FA was positively related to milk, milk fat yield, energy-corrected milk, plasma insulin, and albumin, and negatively related to plasma nonesterified FA (NEFA) and body weight loss. The FA-supplemented diets increased intake of digestible energy, metabolizable energy, and net energy for lactation compared with CON. Compared with CON, FA-supplemented diets increased milk energy output and tended to increase negative energy balance. Increasing dietary cis-9 C18:1 increased intake of digestible energy, metabolizable energy, and net energy for lactation. Although increasing dietary cis-9 C18:1 did not affect milk energy output and energy for maintenance, increasing dietary cis-9 C18:1 improved energy balance. Compared with CON, FA-supplemented diets increased plasma insulin, but we did not observe differences between CON and FA-supplemented diets for NEFA and albumin. Increasing cis-9 C18:1 in FA treatments linearly decreased plasma NEFA and tended to linearly increase insulin and β-hydroxybutyrate. During the carryover period, no treatment differences in blood metabolites were observed. Our results indicate that feeding FA supplements containing C16:0 and cis-9 C18:1 during the immediate postpartum period increased nutrient digestibility, energy intake, and milk energy output compared with a non-fat-supplemented control diet. Increasing dietary cis-9 C18:1 increased energy intake, reduced markers of body fat mobilization, and improved energy balance during the immediate postpartum.

Altering the ratio of dietary palmitic and oleic acids affects production responses during the immediate postpartum and carryover periods in dairy cows

The objectives of our study were to determine the effects of altering the dietary ratio of palmitic (C16:0) and oleic (cis-9 C18:1) acids on production and metabolic responses of early-lactation dairy cows during the immediate postpartum period and to evaluate carryover effects of the treatment diets early in lactation. Fifty-six multiparous cows were used in a randomized complete block design and randomly assigned to 1 of 4 treatments (14 cows per treatment) fed from 1 to 24 d in milk (DIM). The treatments were: (1) control (CON) diet not supplemented with fatty acids (FA); (2) diet supplemented with a FA blend containing 80% C16:0 and 10% cis-9 C18:1 (80:10); (3) diet supplemented with a FA blend containing 70% C16:0 and 20% cis-9 C18:1 (70:20); and (4) diet supplemented with a FA blend containing 60% C16:0 and 30% cis-9 C18:1 (60:30). The FA supplement blends were added at 1.5% of diet DM by replacing soyhulls in the CON diet. All cows were offered a common diet from d 25 to 63 postpartum (carryover period) to evaluate carryover effects. Three preplanned contrasts were used to compare treatment differences: CON versus FA-supplemented diets (80:10 + 70:20 + 60:30)/3; the linear effect of cis-9 C18:1 inclusion in diets; and the quadratic effect of cis-9 C18:1 inclusion in diets. During the treatment period, FA-supplemented diets increased milk yield, 3.5% fat-corrected milk (FCM), and energy-corrected milk (ECM) compared with CON. Compared with CON, FA-supplemented diets increased milk fat content, milk fat yield, yield of mixed FA, and tended to increase protein yield and lactose yield. Also, compared with CON, FA-supplemented diets tended to increase body condition score (BCS) change. A treatment by time interaction was observed for body weight (BW), due to 80:10 inducing a greater BW loss over time compared with other treatments. Increasing cis-9 C18:1 in FA treatments tended to linearly increase dry matter intake (DMI) but did not affect milk yield, 3.5% FCM, ECM, and the yields of milk fat, protein and lactose. Increasing cis-9 C18:1 in FA treatments linearly decreased milk fat content and milk lactose content. Also, increasing cis-9 C18:1 in FA treatments linearly decreased BW and BCS losses. During the carryover period, compared with CON, FA-supplemented diets tended to increase milk yield. Also, FA-supplemented diets increased 3.5% FCM, ECM, and milk fat yield, and tended to increase milk protein yield compared with CON. A treatment by time interaction was observed for BW due to 80:10 increasing BW over time compared with CON. Our results indicate that feeding FA supplements containing C16:0 and cis-9 C18:1 during the immediate postpartum period increased milk yield and ECM compared with a nonfat supplemented control diet. Increasing cis-9 C18:1 in the FA supplement increased DMI and reduced BW and BCS losses. Additionally, the fat-supplemented diets fed during the immediate postpartum period had a positive carryover effect during early lactation, when cows were fed a common diet.

Milk production responses to altering the dietary ratio of palmitic and oleic acids varies with production level in dairy cows

We evaluated the effects of altering the dietary ratio of palmitic (C16:0; PA) and oleic (cis-9 C18:1; OA) acids on production responses of cows with a wide range of milk production (32 to 65 kg/d) in a crossover design experiment with a preliminary period. Thirty-two multiparous Holstein cows (144 ± 54 d in milk) were assigned randomly to a treatment sequence. Treatments were diets supplemented with fatty acid (FA) blends (1.5% of diet dry matter) that provided 80% C16:0 + 10% cis-9 C18:1 (PA) and 60% C16:0 + 30% cis-9 C18:1 (PA+OA). The corn silage and alfalfa-based diets contained 20.0% forage neutral detergent fiber (NDF), 28.5% starch, and 17.1% crude protein. Treatment periods were 21 d with the final 5 d used for data and sample collection. Treatment did not affect dry matter intake (DMI), milk yield, energy-corrected milk (ECM), body weight, or body weight change. The PA+OA diet increased total, 16-carbon, and 18-carbon FA digestibility compared with the PA diet. Compared with PA+OA, PA increased fat yield (1.97 vs. 1.91 kg/d) and protein yield (1.61 vs. 1.55 kg/d). The PA diet also increased the yield of de novo (448 vs. 428 g/d) and mixed (749 vs. 669 g/d) milk FA and decreased the yield of preformed FA (605 vs. 627 g/d) compared with PA+OA. Interactions were detected between treatment and preliminary milk yield for DMI, total FA intake, 16-carbon FA intake, ECM, 3.5% fat-corrected milk (linear interaction), and a tendency for milk yield (linear interaction); lower-producing cows (<45 kg/d) had increased DMI and ECM on the PA diet, whereas higher-producing cows (>55 kg/d) had increased DMI and ECM on the PA+OA diet. A linear interaction was detected between treatment and preliminary milk yield for mixed milk FA yield (linear interaction) and a tendency for de novo milk FA yield (linear interaction). Our results demonstrate that feeding a fat supplement containing more cis-9 C18:1 replacing C16:0 increased production responses (DMI, milk yield, and ECM) in higher-producing cows, but decreased production responses in lower-producing cows.

Modeling fatty acids for dairy cattle: Models to predict total fatty acid concentration and fatty acid digestion of feedstuffs

Development of predictive models of fatty acid (FA) use by dairy cattle still faces challenges due to high variation in FA composition among feedstuffs and fat supplements. Two meta-analytical studies were carried out to develop empirical models for estimating (1) the total FA concentration of feedstuffs, and (2) the apparent total-tract digestibility of total FA (DCFA_TTa) in dairy cows fed different fat types. In study 1, individual feedstuff data for total crude fat (EE) and FA were taken from commercial laboratories (total of 203 feeds, 1,170,937 samples analyzed for total FA, 1,510,750 samples analyzed for total EE), and data for FA composition were collected from the Cornell Net Carbohydrate and Protein System feed library. All feedstuffs were grouped into 7 classes based on their nutritional components. To predict total FA concentration (% of dry matter) for groups of feeds, the total EE (% of dry matter) was used as an independent variable in the model, and all models were linear. For forages, data were weighted using the inverse of the standard error (SE). Regression coefficients for predicting total FA from EE (% of dry matter) were 0.73 (SE, 0.04), 0.98 (0.02), 0.80 (0.02), 0.61 (0.04), 0.92 (0.03), and 0.93 (0.03), for animal protein, plant protein, energy sources, grain crop forage, by-product feeds, and oilseeds, respectively. The intercepts for plant protein and by-product groups were different from zero and included in the models. As expected, forages had the lowest total FA concentration (slope = 0.57, SE = 0.02). In study 2, data from 30 studies (130 treatment means) that reported DCFA_TTa in dairy cows were used. Data for animal description, diet composition, intakes of total FA, and DCFA_TTa, were collected. Dietary sources of fat were grouped into 11 categories based on their fat characteristic and FA profile. A mixed model including the random effect of study was used to regress digested FA on FA intake with studies weighted according to the inverse of their variance (SE). Dietary intake of extensively saturated triglycerides resulted in markedly lower total FA digestion (DCFA_TTa = 44%) compared with animals consuming unsaturated FA, such as Ca-salts of palm (DCFA_TTa = 76%) and oilseeds (DCFA_TTa = 73%). Cows fed saturated fats had lower total FA digestion among groups, but it was dependent on the FA profile of each fat source. The derived models provide additional insight into FA digestion in ruminants. Predictions of total FA supply and its digestion can be used to adjust fat supplementation programs for dairy cows.

Use of indirect calorimetry to evaluate utilization of energy in lactating Jersey dairy cattle consuming diets with increasing inclusion of hydrolyzed feather meal

A study using indirect calorimetry and 12 lactating multiparous Jersey cows (53 ± 23 d in milk at the beginning of the experiment; mean ± standard deviation) was conducted to evaluate the utilization of energy in cattle consuming diets containing increasing hydrolyzed feather meal (HFM). A triplicated 4 × 4 Latin square design with 35-d periods (28-d adaption and 4-d collections) was used to compare 4 different dietary treatments. Treatments contained (DM basis) HFM at 0% (0HFM), 3.3% (3.3HFM), 6.7% (6.7MFM), and 10.0% (10HFM). Diets were formulated such that HFM replaced blood meal and nonenzymatically browned soybean meal. With increasing HFM, linear increases were observed for dietary NEL content (1.61, 1.64, 1.69, and 1.70 ± 0.042 Mcal/kg of DM for 0HFM, 3.3HFM, 6.7MFM, and 10HFM, respectively), and the efficiency of converting ME to NEL (0.708, 0.711, 0.717, and 0.719). Apparent total-tract digestibility of CP linearly decreased with increasing HFM (63.4, 61.1, 59.9, and 58.6 ± 1.46% for 0HFM, 3.3HFM, 6.7MFM, and 10HFM, respectively), whereas long-chain fatty acid digestibility increased with increasing HFM (77.2, 77.7, 78.5, and 80.6 ± 1.30%). With increased inclusion of HFM, fecal N excretion increased (199, 230, 239, 237 ± 12.1 g/d for 0HFM, 3.3HFM, 6.7MFM, and 10HFM, respectively), whereas urinary N excretion decreased (166, 151, 155, and 119 ± 14.8 g/d). Increasing the concentration of HFM resulted in a quadratic effect on DMI (19.6, 20.2, 20.3, and 19.1 ± 0.79 kg/d for 0HFM, 3.3HFM, 6.7MFM, and 10HFM, respectively) and milk yield (31.7, 32.0, 31.9, and 29.7 ± 1.32 kg/d). Increasing HFM linearly decreased the milk protein concentration (3.34, 3.29, 3.23, and 3.23 ± 0.158 for 0HFM, 3.3HFM, 6.7MFM, and 10HFM, respectively) and yield (1.05, 1.05, 1.02, and 0.96 ± 0.040 kg). The inclusion of HFM did not affect energy-correct milk yield (average of 39.3 ± 1.54). Results of this study suggest that HFM can increase dietary NEL content compared with blood meal and nonenzymatically browned soybean meal and maintained energy-corrected milk yield; however, feeding HFM at greater than 6.7% of diet DM decreased DMI, and protein availability may have been reduced with increased HFM, leading to a linear decrease in milk protein concentration and yield.

Effects of commercially available palmitic and stearic acid supplements on nutrient digestibility and production responses of lactating dairy cows

We evaluated the effects of commercially available fatty acid (FA) supplements containing palmitic (C16:0) and stearic acid (C18:0) on nutrient digestibility and production responses of dairy cows. Thirty-six mid-lactation (146 ± 55 d in milk) multiparous Holstein cows were randomly assigned to twelve 3 × 3 balanced truncated Latin squares, with 3 treatments and 2 consecutive 35-d periods, with the final 5 d used for sample and data collection. Treatments were (1) a control diet containing no supplemental FA (CON), (2) a control diet supplemented with a commercially available C16:0 supplement (PA), and (3) a control diet supplemented with a commercially available C16:0 and C18:0 supplement (MIX). Supplements were fed at 1.5% dry matter and replaced soyhulls in CON. The statistical model included the random effect of cow nested within square and the fixed effects of treatment, period, square, and their interactions. Preplanned contrasts were (1) overall effect of FA treatments [CON vs. the average of the FA treatments (FAT); 1/2 (PA + MIX)], and (2) effect of FA supplement (PA vs. MIX). Treatment had no effects on dry matter intake, body weight, or body weight change. Compared with CON, FAT decreased digestibilities of total FA and 18-carbon FA but did not affect dry matter and neutral detergent fiber digestibility. Compared with MIX, PA increased dry matter and neutral detergent fiber digestibilities by 3.6 and 4.8 percentage units, respectively. The PA also increased total FA and 18-carbon FA digestibilities but did not alter 16-carbon FA digestibility compared with MIX. Using a Lucas test, we estimated apparent digestibility coefficients of 0.768 and 0.553 for the PA and MIX supplements, respectively. Compared with CON, FAT increased milk yield and tended to increase energy-corrected milk, but did not affect yield of milk fat or milk protein. The PA increased energy-corrected milk and milk fat yield but had no effect on milk protein yield compared with MIX. Our results indicate that dairy cows producing around 45 kg of milk respond better to a FA supplement enriched in C16:0 compared with a supplement containing both C16:0 and C18:0, which is likely due in part to PA increasing FA and neutral detergent fiber digestibility compared with MIX.