Effect of combining the methanogenesis inhibitor 3-nitrooxypropanol and cottonseeds on methane emissions, feed intake, and milk production of grazing dairy cows.

No single enteric CH4 mitigating strategy has been consistently effective or is readily applicable to ruminants in grassland systems. When CH4 mitigating strategies are effective under grazing conditions, mitigation is mild to moderate at best. A study was conducted to evaluate the potential of combining two CH4 mitigation strategies deemed feasible to apply in grazing dairy cows, the methanogenesis inhibitor 3-nitrooxypropanol additive (3-NOP) and cottonseed supplementation (CTS), seeking to enhance their individual CH4 mitigating potential. Forty-eight dairy cows were evaluated in a continuous grazing study and supplemented with either a starch-based concentrate (STA) or one that contained cottonseeds (1.75 kg DM/d; CTS), and with either 19 g/d of 10% 3-NOP (Bovaer®) or the additive's carrier (placebo), in a 2 × 2 factorial arrangement of treatments. Treatments were supplied mixed with a concentrate supplement (5 kg/d as fed) and offered in two equal rations at milking. Methane emissions were measured on weeks 4 and 8 using the sulphur hexafluoride tracer gas technique over a 5-d period. The 3-NOP and CTS treatments tended to interact on absolute CH4 such that 3-NOP decreased CH4 by 13.4% with STA, but there was no mitigation with 3-NOP and CTS. Treatment interactions were also obtained for CH4 yield, where 3-NOP tended to decrease CH4 when supplied with STA, and tended to increase it with CTS. The increase in CH4 yield with the CTS diet was driven by a numerical decrease in DM intake. Methane intensity was not affected by the 3-NOP or CTS treatments. Total volatile fatty acids in ruminal fluid were not affected by 3-NOP supplementation, but a reduction in acetate and an increase in propionate proportion occurred, resulting in decreased acetate: propionate. The 3-NOP additive decreased grass intake; however, energy-corrected milk yield and milk composition were largely unaffected. Milk urea increased with 3-NOP supplementation. Combining twice daily supplementation of 3-NOP and CTS did not enhance their CH4 mitigation potential when fed to grazing dairy cows. The relatively low inhibition of CH4 production by 3-NOP compared to studies with total mixed rations may result from the mode of delivery (pulse dosed twice daily) and time gap caused by experimental handling and moving of animals to pasture after 3-NOP supplementation in the milking parlour, which could have impaired the synchrony between the additive presence in the rumen and grass intake in paddocks.

Effect of dietary supplementation of sodium acetate and calcium butyrate on milk fat synthesis in lactating dairy cows.

Acetate is a major source of energy and substrate for milk fat synthesis in the dairy cow. We recently reported a linear increase in milk fat yield and greater than a 30% net apparent transfer of acetate to milk fat with ruminal infusion of neutralized acetate. Additionally, ruminal acetate infusion linearly increases plasma ß-hydroxybutyrate. The objective of the current study was to investigate the ability of acetate and butyrate fed in a diet to increase milk fat synthesis. Twelve multiparous lactating Holstein cows were randomly assigned to treatments in a 3 × 3 Latin square design with 14-d periods that included a 7-d washout followed by 7 d of treatment. Cows were fed ad libitum a basal diet with a low risk for biohydrogenation-induced milk fat depression, and treatments were mixed into the basal diet. Treatments were 3.2% NaHCO3 (control), 2.9% sodium acetate, and 2.5% calcium butyrate (carbon equivalent to acetate treatment) as a percent of diet dry matter. Feeding sodium acetate increased dry matter intake by 2.7 kg, had no effect on milk yield, and increased milk fat yield by 90 g/d and concentration by 0.2 percentage units, compared with control. Calcium butyrate decreased dry matter intake by 2.6 kg/d, milk yield by 1.65 kg/d, and milk fat yield by 60 g/d, compared with control. Sodium acetate increased concentration and yield of 16 carbon mixed source fatty acids (FA) and myristic acid, while decreasing the concentration of preformed FA, compared with control. Calcium butyrate had no effect on concentration of milk FA by source, but increased concentration of trans-10 C18:1 in milk by 18%, indicating a shift in rumen biohydrogenation pathways. Our data demonstrate that milk fat yield and concentration can be increased by feeding sodium acetate at 2.9% of diet dry matter, but not by feeding calcium butyrate at an equivalent carbon mass.

Factors associated with the content of mammary-synthesized fatty acids in milk fat: A meta-analysis.

Consumption of specific fatty acids (FA) that are synthesized in the mammary gland, namely de novo FA, has implications for human health. The objective of the present meta-analysis was to study the associations between milk fat content of de novo FA, with (1) diet composition, and (2) milk production and composition. Milk FA data from 96 peer-reviewed studies published between 1990 and 2016 that included 324 treatment means from 83 bovine experiments, 36 treatment means from 12 caprine experiments, and 40 treatment means from 12 ovine experiments were used in this analysis. Individual species models including the fixed effect of experiment were fitted using multiple regression to explain milk content of de novo FA as a function of diet composition and milk production and composition variables. We also evaluated replacing the effect of the experiment by the effect of the experiment nested in the laboratory at which the research had been conducted, and the effect of the laboratory. Butyric acid content in milk fat was positively but weakly related to dietary ether extract in does and ewes. Lauric, myristic, and palmitic acid contents in milk fat were negatively related to dietary ether extract in does and to a somewhat lesser extent in cows and ewes. The results confirm that the inclusion of lipids in the diet may not only affect the availability of preformed FA but also the profile of FA synthesized de novo in the mammary gland. Most of the variation in all prediction models was explained by the experiment or by the laboratory if the latter was included in the model. The ample variation in analytical methods reported by the different research groups suggests that differences in analytical protocols might explain a substantial proportion of the variation in de novo FA profile. A main conclusion of this study is the potential influence of differences in analytical procedures to explain the variation in de novo FA profile. Standardization of methods of FA analysis to improve reproducibility seems to be an aspect of importance to this area of research.

Effect of conjugated linoleic acid and acetate on milk fat synthesis and adipose lipogenesis in lactating dairy cows.

During biohydrogenation-induced milk fat depression (MFD), nutrients are spared from milk fat synthesis and are available for other metabolic uses. Acetate is the major carbon source spared and it may increase lipid synthesis in adipose tissue during MFD. The objective of this study was to compare the effect of trans-10,cis-12 conjugated linoleic acid (CLA) and the amount of acetate spared during CLA-induced MFD on adipose tissue lipogenesis. Nine multiparous, lactating, ruminally cannulated Holstein cows (244 ± 107 d in milk; 25 ± 8.4 kg of milk/d; mean ± standard deviation) were randomly assigned to treatments in a 3 × 3 Latin square design. Experimental periods were 4 d followed by a 10-d washout. Treatments were control (CON), ruminal infusion of acetate (AC; continuous infusion of 7 mol/d adjusted to pH 6.1 with sodium hydroxide), or abomasal infusion of CLA (10 g/d of both trans-10,cis-12 CLA and cis-9,trans-11 CLA). Dry matter intake, milk yield, and milk protein yield and percentage were not affected by treatments. Compared with CON, milk fat yield decreased 23% and fat percent decreased 28% in CLA, and milk fat yield increased 20% in AC. Concentration and yield of milk de novo synthesized fatty acids (C16) was increased by CLA, compared with CON. Yield of de novo synthesized fatty acids and palmitic acid was increased by AC, compared with CON. Lipogenesis capacity of adipose tissue explants was decreased 72% by CLA, but was not affected by AC. Acetate oxidation by adipose explants was not affected by treatments. Treatments had no effect on expression of key lipogenic factors, lipogenic enzymes, and leptin; however, expression of fatty acid binding protein 4 was reduced in CLA compared with CON. Additionally, hormone-sensitive lipase and perilipin 1 were decreased by CLA and acetate. Plasma glucose and glucagon concentrations were not affected by treatments; however, CLA increased nonesterified fatty acids 17.7%, ß-hydroxybutyrate 16.1%, and insulin 27.8% compared with CON, and AC increased plasma ß-hydroxybutyrate 18%. In conclusion, during CLA-induced MFD in low-producing cow adipose tissue was sensitive to the anti-lipogenic effects of CLA, while spared acetate did not stimulate adipose lipogenesis. However, acetate may play an important role in stimulating lipogenesis and improving energy status in the mammary gland under normal conditions.

The effect of conjugated linoleic acid, acetate, and their interaction on adipose tissue lipid metabolism in nonlactating cows.

During biohydrogenation-induced milk fat depression, adipose tissue lipogenesis may be increased through nutrients spared from milk fat synthesis. However, the direct effect of trans-10,cis-12 conjugated linoleic acid (CLA) and the indirect effect of spared nutrients on adipose tissue lipogenesis during milk fat depression is not clear. The objective of this study was to determine the direct effect of CLA, spared acetate, and their interaction on adipose tissue lipogenesis using nonlactating dairy cows as an experimental model, which allows separation of the effect of CLA and nutrient sparing. Eight ruminally cannulated, multiparous nonlactating and pregnant Holstein cows were randomly assigned to treatments in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Factors were CLA and acetate, and treatments were control (CON), rumen acetate infusions (Ac; continuous infusion of 7 mol/d adjusted to pH 6.1 with sodium hydroxide), abomasal infusion of trans-10,cis-12 CLA (CLA; 10 g/d of both trans-10,cis-12 CLA and cis-9,trans-11 CLA), and Ac + CLA (Ac + CLA). Dry matter intake was not affected by Ac, but tended to decrease by CLA. Plasma trans-10,cis-12 CLA concentration as a percentage of fatty acids was increased by 0.3 percentage points by CLA. No treatment effect was observed on plasma glucose and ß-hydroxybutyrate, but an interaction was observed of CLA and Ac on plasma insulin and nonesterified fatty acids. Insulin was increased 24% by CLA, but not by Ac + CLA, and nonesterified fatty acids were increased 55% by Ac + CLA, but not by CLA alone. Lipogenesis and oxidation capacity of adipose tissue explants were not affected by treatments. Adipose expression of key lipogenic factors (peroxisome proliferator-activated receptor γ2 and sterol response element binding protein 1c) were reduced by CLA, by the interaction of Ac and CLA (sterol response element binding protein 1c), and tended to be reduced with Ac (S14 and peroxisome proliferator-activated receptor γ1). Expression of several adipose lipogenic enzymes (fatty acid synthase, acetyl-CoA carboxylase, and stearoyl-CoA desaturase 1) was reduced by CLA and Ac. An interaction was observed of Ac and CLA for fatty acid binding protein 4, which was decreased by Ac, but not Ac + CLA. In conclusion, in the nonlactating cow, adipose tissue is sensitive to the anti-lipogenic effects of trans-10,cis-12 CLA at the transcription level and acetate does not stimulate lipogenesis.

Topical treatment of onychomycosis.

Onychomycosis continues to be one of the more common foot problems encountered by podiatrists. Although a reliable cure is elusive, this article reviews several new agents that show some promise.

[How current is the rubber dam method?]. / Wie aktuell ist die Kofferdam-Trockenlegung?

The coffer dam application is still a condition necessary for the successful treatment of pulpitis and periodontitis. It keeps the operating area perfectly dry and prevents incidents in endodontics. The various coffer dam techniques and their indications are described.