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.

Effect of increasing dietary inclusion of whole cottonseed on nutrient digestibility and milk production of high-producing dairy cows.

We determined the effects increasing dietary inclusion of whole cottonseed (WCS) on nutrient digestibility and milk production responses of high-producing dairy cows. Twenty-four multiparous Holstein cows (mean ± SD; 52.7 ± 2.63 kg/d of milk; 104 ± 23 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were increasing doses of WCS at 0, 8, 16, and 24% DM, with WCS replacing soybean meal and hulls to maintain similar diet nutrient composition (%DM) of NDF (32%), forage NDF (21%), starch (27%), and CP (17%). Total fatty acid (FA) content of each treatment was 1.70, 2.96, 4.20, and 5.40%DM, respectively. Three preplanned contrasts were used to test the linear, quadratic, and cubic effects of increasing dietary WCS. Increasing dietary WCS from 0 to 24% DM quadratically influenced intakes of DM and NDF, with the highest value being for the 8% WCS, and intakes of 16- and 18-carbon, and total FA, with maximum values obtained up to 24% WCS. Increasing dietary WCS affected digestibility of DM (cubic) and NDF (quadratic), with the lowest values being for the 8% WCS. Increasing WCS increased 16-carbon digestibility (quadratic) but decreased digestibility of 18-carbon and total FA (both quadratic), with highest and lowest values for the 24% WCS, respectively. Increasing dietary WCS quadratically increased absorbed 16- and 18-carbon, and total FA, with maximum values obtained for 24% WCS. Increasing dietary WCS quadratically increased yields of milk, milk fat, milk protein, milk lactose, 3.5% fat corrected milk, and energy corrected milk, and linearly increased body weight gain. The source of milk FA was affected by dietary WCS, with a quadratic decrease in the yield of de novo and mixed milk FA and a quadratic increase in preformed milk FA. Increasing dietary WCS linearly increased trans-10 C18:1 milk FA content. As dietary WCS increased, plasma insulin linearly decreased, and plasma gossypol levels linearly increased. Despite the decrease in total FA digestibility, increasing dietary WCS from 0 to 24% DM increased FA absorption. Increasing dietary inclusion of WCS up to 16% DM increased milk production responses and DM intake. Under the current dietary conditions, high-producing dairy cows benefited best from a diet containing 8-16% DM inclusion of WCS.

Milk production responses of dairy cows to fatty acid supplements with different ratios of palmitic and oleic acids in low- and high-fat basal diets.

We evaluated the effects of fatty acid (FA) supplements with different ratios of palmitic acid (C16:0) and oleic acid (cis-9 C18:1) in low- and high-FA basal diets on production responses of lactating dairy cows. Thirty-six multiparous Holstein cows (50.2 ± 5.8 kg/d of milk; 160 ± 36 d in milk) were used in a split-plot Latin square design balanced for carryover effects. Cows were blocked by milk yield and allocated to a main plot receiving either a low-FA (LF; 1.93% FA content) basal diet (n = 18) containing cottonseed meal and cottonseed hulls or a high-FA (HF; 3.15% FA content) basal diet (n = 18) containing whole cottonseed. Within each plot, a 3 × 3 Latin square arrangement of treatments was used in 3 consecutive 21-d periods. Treatments were (1) control (CON; no FA supplementation), (2) FA supplement containing 80% C16:0 + 10% C18:1 (PA), and (3) FA supplement containing 60% C16:0 + 30% cis-9 C18:1 (PA+OA). The FA supplements were fed at 1.5% of dry matter and replaced soyhulls in CON. Preplanned contrasts were (1) overall effect of FA supplementation {CON vs. the average of the FA treatments [1/2 (PA + PA+OA)]}, and (2) the effect of the PA treatment versus the PA+OA treatment (PA vs. PA+OA). Treatment by basal diet interactions were observed for yields of milk and lactose, where FA treatments increased yields of milk and milk lactose in LF but not in HF. Basal diet had no effect on dry matter intake (DMI) or milk yield. Compared with LF, HF increased milk fat yield and 3.5% fat-corrected milk (FCM) and tended to increase milk fat content and energy-corrected milk (ECM) yield. The FA treatments decreased DMI but increased the yields of milk fat, 3.5% FCM, and ECM, compared with CON, due to increases in mixed and preformed milk FA yields. The PA+OA treatment decreased DMI and milk protein yield compared with PA. In conclusion, a high-fat basal diet increased milk fat production, and the addition of FA supplements to a low-fat basal diet increased milk lactose yield and tended to increase milk yield. Additionally, regardless of basal diet fat level, FA supplements increased production responses compared with the non-FA-supplemented control diet.

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.

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.

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.

Distribution of metals and radionuclides in the lichens Cladonia rangiferina and C. mitis from the past uranium mining region of Elliot Lake, Ontario, Canada.

The present study was performed in the Elliot Lake area (Ontario, Canada), a site of uranium mining and milling for nearly 40 years between 1950's and 1990's. Although mining activities ceased in the mid-1990's, the site hosts several tailings management areas (TMAs) which are under ongoing rehabilitation and monitoring. Several surveys using lichens as a biomonitoring tool were completed in the 1980s and the 1990s to assess the levels of contaminants. The present survey aimed to re-visit the historical surveys, and to determine the current status of environmental recovery of the area. Our survey consisted of sampling two lichen species, Cladonia rangiferina and C. mitis, in an area covering up to 50 km from the former mining operation and the TMAs. The results reported in this work indicated that the levels of metals and radionuclides, diagnostic of mining operations, have decreased over time: particularly, the U, Th and Pb levels in both lichen species dropped by about two orders of magnitude by the 2020's compared to the 1980's. Likewise, the Cs-137 levels in both lichen species reflect present day global background. The study provides a new set of present-day regional baseline elemental concentrations for other metals that are associated with mining (Cd, As, Ti, Cs). Finally, there were weak but statistically significant differences in the levels of some elements (U, Th, Cd) between the two lichens, suggesting these two species might have different capture mechanisms or retention abilities.

Increasing levels of calcium salts of palm fatty acids affect production responses during the immediate postpartum and carryover periods in dairy cows.

Our objective was to determine the dose-response effects of calcium salts of palm fatty acids (CSPF) on nutrient digestibility and production responses of early-lactation dairy cows grazing on tropical pastures and to evaluate carryover effects throughout mid and late lactation. Forty multiparous dairy cows (Jersey × Holstein) with (mean ± standard error of the mean) 20 ± 1.69 kg of milk/d and 20 ± 5.0 d in milk were used in a randomized complete block design. During the treatment period, all cows were kept in a grazing system. The treatments were offered for 90 d (treatment period) and consisted of 4 increasing levels of CSPF: 0 (0 kg/d), 0.2 (0.2 kg/d), 0.4 (0.4 kg/d), and 0.6 (0.6 kg/d). Each treatment had 10 animals. Increasing CSPF from 0 to 0.6 kg/d replaced an equivalent amount of a corn-based concentrate supplement offered at 10 kg/d on an as-fed basis (8.96 kg/d as a dry matter basis). All cows were housed and received a diet without fat inclusion fed as total mixed ration once a day from 91 to 258 d of the experiment (carryover period). During the treatment period, increasing CSPF linearly decreased dry matter intake (1.20 kg/d), linearly increased neutral detergent fiber digestibility (3.90 percentage units), and quadratically increased total fat digestibility (6.30 percentage units at 0.4 kg/d CSPF). Increasing CSPF linearly increased the yields of milk (4.10 kg/d), milk fat (0.11 kg/d), milk lactose (0.19 kg/d), energy-corrected milk (ECM; 3.30 kg/d), and feed efficiency (ECM/dry matter intake, 0.34 kg/kg), and linearly decreased milk protein content (0.38 g/100 g), body weight change (0.05 kg/d), and body condition score (0.37). We observed interactions between CSPF and time during the carryover period. Overall, CSPF supplementation linearly increased or tended to increase milk yield until 202 d of the experiment with a similar pattern observed for all the other yield variables. In conclusion, supplementing CSPF from 0 to 0.6 kg/d during 90 d increased neutral detergent fiber and total fat digestibility and the yields of milk, milk fat, and ECM in early-lactation dairy cows grazing on tropical pastures. Most production measurements linearly increased during the treatment period, indicating that 0.6 kg/d CSPF was the best dose. Also, supplementing CSPF from 0 to 0.6 kg/d for 90 d during early lactation had positive carryover effects across mid and late lactation.

Lipopolysaccharide challenge following intravenous amino acid infusion in postpartum dairy cows: I. Production, metabolic, and hormonal responses.

Postpartum cows experience a nadir in energy and AA deficit early postpartum. At the same time, cows are challenged with inflammatory stimuli and often show heightened immune responsiveness, further increasing their metabolic needs during this critical time. This study investigated the response to a systemic inflammatory stimulus after a 4-d intravenous (IV) AA infusion designed to ameliorate the estimated metabolizable protein (MP) deficit in postpartum cows. Our objectives were to (1) describe the production and metabolic responses to early postpartum IV AA infusion, (2) determine the metabolic and hormonal responses to an acute IV lipopolysaccharide (LPS) challenge in early postpartum cows, and (3) compare these metabolic and hormonal responses between IV AA treated and control cows. Cows (n = 14, 4 ± 1 d in milk) were continuously IV infused for 4 d in a matched-pair randomized controlled design and received IV AA (IVAA) or 0.9% NaCl (CTRL). Treatment with IV AA consisted of 1 g/kg of BW per day of combined essential AA (EAA) and nonessential AA (NEAA). After infusion ended, cows were challenged IV with LPS (0.0625 µg/kg of BW over 1 h), and serial blood samples were collected to quantify AA, metabolite, and hormone concentrations. Amino acid infusion increased plasma EAA and NEAA concentrations and ameliorated the estimated MP deficit but not the metabolizable energy deficit in IVAA cows. Patterns of dry matter intake during infusion were different between groups. Milk yield and milk protein content and yield were unaffected, but IV AA was associated with increased milk fat content and yield of both de novo and preformed fatty acids. Before LPS infusion, plasma EAA and NEAA concentrations were greater in IVAA compared with CTRL. During LPS challenge, plasma AA concentrations decreased to a greater degree in IVAA than CTRL. Glucagon concentrations were greater and glucose concentrations lower in IVAA during challenge; however, previous AA infusion did not affect the time-dependent changes in concentrations of energy metabolites or glucoregulatory hormones. Plasma urea nitrogen concentration increased in both treatments following challenge, although the temporal pattern depended on treatment. Effects of AA infusion on milk fat response were pronounced and likely due to a combination of increased lipolysis and de novo milk fat synthesis. Despite differences in circulating concentrations of nutrients and hormones before challenge, metabolic responses to systemic inflammation did not differ between the 2 treatments. We conclude that AA infusion changed metabolic status and milk fat but did not appear to alter the metabolic response to subsequent systemic inflammation.

Nutrient digetibility and production responses of lactating dairy cows when saturated free fatty acid supplements are included in diets: A meta-analysis.

Our objective was to perform a series of meta-analyses to evaluate the effects of diets supplemented with saturated free fatty acid (FA) supplements (SFAA) compared with nonfat supplemented control diets (CON) on nutrient digestibility and production responses of lactating dairy cows and to determine whether experimental design affects responses to SFFA. We divided SFFA into C16:0-enriched supplements (PALM, FA supplements with ≥80% C16:0) and C16:0+C18:0-enriched supplements (MIX, FA supplements with ≥80% C16:0+C18:0). The database was formed from 32 peer-reviewed publications with SFFA supplemented at ≤3% diet dry matter (DM). We completed 3 different meta-analyses to meet our objectives. We analyzed the interaction between experimental design (continuous vs. change-over) and treatments (CON vs. SFFA; Meta.1). Regardless of experimental design, we evaluated the effect of treatment (CON vs. PALM vs. MIX; Meta.2) and the effect of 1-percentage-unit increase of MIX and PALM in diet DM (Meta.3). In Meta.1, there was no interaction between treatments and experimental design for any variable. In Meta.2, compared with CON, MIX had no effect on NDF digestibility, milk protein yield and energy corrected milk (ECM), increased the yields of milk (1.20 kg/d) and milk fat (0.04 kg/d), and decreased FA digestibility (5.20 percentage units). Compared with CON, PALM increased NDF digestibility (4.50 percentage units), the yields of milk (1.60 kg/d), milk fat (0.10 kg/d), milk protein (0.04 kg/d), and ECM (2.00 kg/d), and had no effect on FA digestibility. Compared with MIX, PALM tended to increase FA digestibility (3.20 percentage units), increased NDF digestibility (3.50 percentage units), milk fat yield (0.06 kg/d), and ECM (1.20 kg/d). In Meta.3, for each 1-percentage-unit increase of supplemental FA in diet DM, MIX had no effect on NDF digestibility, decreased FA digestibility, increased the yields of milk and milk fat, had no effect on milk protein yield, ECM and milk fat content, and decreased milk protein content. For each 1-percentage-unit increase of supplemental FA in diet DM, PALM increased NDF digestibility, had no effect on FA digestibility, increased the yields of milk, milk fat, ECM and milk fat content, tended to increase milk protein yield, and had no effect on milk protein content. Our results indicate no reason for the restrictive use of change-over designs in saturated FA supplementation studies and meta-analyses. Lactating dairy cows responded better to a FA supplement enriched in C16:0 compared with one containing C16:0 and C18:0.

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.

Prediction of fatty acid composition using milk spectral data and its associations with various mid-infrared spectral regions in Michigan Holsteins.

Fatty acid composition in milk is not only reflective of nutritional quality but also potentially predictive of other attributes (e. g. including the cow's energy balance and its relative output of methane emissions). Furthermore, a higher ratio of long-chain to short-chain fatty acids or mean carbon number has been associated with negative energy balance in dairy cows, whereas enhanced nutritional properties have been generally associated with higher levels of unsaturation. We set out to directly compare Bayesian regression strategies with partial least squares for the prediction of various milk fatty acids using Fourier-transform infrared spectrum data on 777 milk samples taken from 579 cows on 4 Michigan dairy herds between 5 and 90 d in milk. We also set out to identify those spectral regions that might be associated with fatty acids and whether carbon number or level of unsaturation might contribute to the strength of these associations. These associations were based on adaptively clustered windows of wavenumbers to mitigate the distorting effects of severe multicollinearity on marginal associations involving individual wavenumbers. In general, Bayesian regression methods, particularly the variable selection method BayesB, outperformed partial least squares regression for cross-validation prediction accuracy for both individual fatty acids and fatty acid groups. Strong signals for wavenumber associations using BayesB were well distributed throughout the mid-infrared spectrum, particularly between 910 and 3,998 cm-1. Carbon number appeared to be linearly related to strength of wavenumber associations for 38 moderately to highly predicted fatty acids within the spectral regions of 2,286 to 2,376 and 2,984 to 3,100 cm-1, whereas nonlinear associations were determined within 1,141 to 1,205; 1,570 to 1,630; and 1,727 to 1,768 cm-1. However, no such associations were detected with level of unsaturation. Spectral regions where there were significant relationships between strength of association and carbon number may be useful targets for inferring the relative proportion of long-chain to short-chain fatty acids, and hence energy balance.

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.

A review of guidelines for evaluating a minor modification to a validated assay.

Any modification to a validated assay must be evaluated in terms of the impact on the assay's performance characteristics and whether the assay remains fit for the intended purpose. The comparison is referred to as a 'method comparison', 'method comparability', 'method change', or 'comparative validation'. This review presents recommendations and examples of studies found in the current literature as a means of assessing minor modifications. In addition, the authors discuss common statistical approaches used for these comparisons.

Toute modification apportée à un essai validé doit être évaluée afin de mesurer l'impact de cette modification sur les paramètres de performances de l'essai et déterminer si l'aptitude à l'emploi qui lui a été assigné demeure valable suite à la modification en question. Cette comparaison est désignée sous les termes de « comparaison de méthodes d'essai ¼, « comparabilité de méthodes ¼, « changement de méthode d'essai ¼ ou « validation comparative ¼. Les auteurs font part de leurs recommandations et donnent des exemples d'études émanant de la littérature récente concernant l'évaluation de modifications mineures. En outre, ils examinent les approches statistiques couramment utilisées pour ces comparaisons.

Toda modificación que se introduzca en un ensayo validado debe ser objeto de evaluación para determinar la influencia del cambio en las características de funcionamiento del ensayo y saber si este sigue estando adaptado a su función. Para referirse a la comparación, los autores emplean expresiones como 'comparación de métodos', 'comparabilidad de métodos', 'cambio de método' o 'validación comparativa'. Los autores presentan aquí recomendaciones y ejemplos de estudios extraídos de la bibliografía actual como medio de evaluar modificaciones de importancia menor. Además, los autores examinan las lógicas estadísticas comunes utilizadas para estas comparaciones.

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 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.

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 ß-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.

Effects of prepartum diets varying in dietary energy density and monensin on early-lactation performance in dairy cows.

Our objectives were to evaluate the effects of prepartum monensin supplementation and dry-period nutritional strategy on the postpartum productive performance of cows fed monensin during lactation. A total of 102 Holstein cows were enrolled in the experiment (32 primiparous and 70 multiparous). The study was a completely randomized design, with randomization restricted to balance for parity, body condition score, and expected calving date. A 2 × 2 factorial arrangement of prepartum treatments was used; the variables of interest were prepartum feeding strategy [controlled-energy diet throughout the dry period (CE) vs. controlled-energy diet from dry-off to 22 d before expected parturition, followed by a moderate-energy close-up diet from d 21 before expected parturition through parturition (CU)] and prepartum monensin supplementation [0 g/t (control, CON) or 24.2 g/t (MON); Rumensin; Elanco Animal Health, Greenfield, IN]. Lactation diets before and after the dry period contained monensin at 15.4 g/t. During the close-up period, cows fed CU had greater DM and NEL intakes than cows fed CE. Calf BW at birth tended to be greater for cows fed CU than for those fed CE but was not affected by MON supplementation. Diet did not affect calving difficulty score, but cows supplemented with MON had an increased calving difficulty score. We found a tendency for a MON × parity interaction for colostral IgG concentration, such that multiparous MON cows tended to have lower IgG concentration than CON cows, but colostral IgG concentration for primiparous MON and CON cows did not differ. Postpartum milk yield did not differ between diets but tended to be greater for cows supplemented with MON. Milk fat and lactose content were greater for cows fed CU than for those fed CE, and lactose content and yield were increased for cows supplemented with MON. Solids-corrected and fat-corrected milk yields were increased by MON supplementation, but were not affected by diet. Overall means for postpartum DMI did not differ by diet or MON supplementation. The CU diet decreased the concentration of nonesterified fatty acids during the close-up period but increased it postpartum. Neither diet nor monensin affected ß-hydroxybutyrate or liver composition. Overall, postpartum productive performance differed little between prepartum dietary strategies, but cows fed MON had greater energy-corrected milk production. In herds fed monensin during lactation, monensin should also be fed during the dry period.

Effects of physical preparation of diets and inclusion rate of modified wet distillers grains with solubles on production and rumen measurements of lactating dairy cows.

Our objective was to determine if methods for preparing total mixed ration [TMR; horizontal paddle mixer with knives (PK) vs. vertical auger (VA) mixer] would alter the physical form of the TMR and affect utilization of diets with increasing amounts of modified wet distillers grains with solubles (MWDGS). Holstein cows (n = 24 with 12 ruminally cannulated; 144 d in milk ± 31 d at start) were used in a split-plot design with mixer type as the whole plot and MWDGS concentrations as subplots in a replicated 3 × 3 Latin square arrangement with 35-d periods. Inclusion rates of MWDGS were 10, 20, and 30% of dietary dry matter, primarily replacing corn, soybean meal, soyhulls, and whole cottonseed. Feed dry matter intake (DMI) was less for PK (23.8 kg/d) than for VA (25.7 kg/d), but was unaffected by MWDGS concentration. Milk production did not differ by concentration of MWDGS or by interaction of MWDGS × mixer. Milk fat percentage declined with increasing MWDGS but the interaction between mixer and MWDGS showed that decreases were larger with VA mixing. Cows fed the diet containing 30% MWDGS mixed with PK averaged 3.45% (1.24 kg/d) milk fat, whereas cows fed the same diet mixed with VA averaged 2.81% (1.10 kg/d) fat. Concentrations of trans-10,cis-12 C18:2 in milk fat likely explain the differences observed in milk fat yield; the concentration of trans-10,cis-12 C18:2 increased as MWDGS was increased and the MWDGS × mixer interaction showed that VA had greater concentrations. Greater mean particle size and increased variation in particle size with VA may partially explain differences in milk fat via increased sorting that allowed for an altered rumen environment and favored alternative biohydrogenation pathways. Feed conversion efficiency (FCE; energy-corrected milk/DMI) decreased linearly as MWDGS increased, but FCE tended to be maintained when higher MWDGS diets were mixed using PK rather than VA. Ruminal pH and ammonia concentration decreased linearly as MWDGS increased. The PK mixer resulted in greater FCE when higher amounts of MWDGS were fed, primarily because milk fat content and yield were not as depressed and DMI was lower at similar milk yields.