Methane prediction based on individual or groups of milk fatty acids for dairy cows fed rations with or without linseed.

Milk fatty acids (MFA) are a proxy for the prediction of CH4 emission from cows, and prediction differs with diet. Our objectives were (1) to compare the effect of diets on the relation between MFA profile and measured CH4 production, (2) to predict CH4 production based on 6 data sets differing in the number and type of MFA, and (3) to test whether additional inclusion of energy-corrected milk (ECM) yield or dry matter intake (DMI) as explanatory variables improves predictions. Twenty dairy cows were used. Four diets were used based on corn silage (CS) or grass silage (GS) without (L0) or with linseed (LS) supplementation. Ten cows were fed CS-L0 and CS-LS and the other 10 cows were fed GS-L0 and GS-LS in random order. In feeding wk 5 of each diet, CH4 production (L/d) was measured in respiration chambers for 48 h and milk was analyzed for MFA concentrations by gas chromatography. Specific CH4 prediction equations were obtained for L0-, LS-, GS-, and CS-based diets and for all 4 diets collectively and validated by an internal cross-validation. Models were developed containing either 43 identified MFA or a reduced set of 7 groups of biochemically related MFA plus C16:0 and C18:0. The CS and LS diets reduced CH4 production compared with GS and L0 diets, respectively. Methane yield (L/kg of DMI) reduction by LS was higher with CS than GS diets. The concentrations of C18:1 trans and n-3 MFA differed among GS and CS diets. The LS diets resulted in a higher proportion of unsaturated MFA at the expense of saturated MFA. When using the data set of 43 individual MFA to predict CH4 production (L/d), the cross-validation coefficient of determination (R2CV) ranged from 0.47 to 0.92. When using groups of MFA variables, the R2CV ranged from 0.31 to 0.84. The fit parameters of the latter models were improved by inclusion of ECM or DMI, but not when added to the data set of 43 MFA for all diets pooled. Models based on GS diets always had a lower prediction potential (R2CV = 0.31 to 0.71) compared with data from CS diets (R2CV = 0.56 to 0.92). Models based on LS diets produced lower prediction with data sets with reduced MFA variables (R2CV = 0.62 to 0.68) compared with L0 diets (R2CV = 0.67 to 0.80). The MFA C18:1 cis-9 and C24:0 and the monounsaturated FA occurred most often in models. In conclusion, models with a reduced number of MFA variables and ECM or DMI are suitable for CH4 prediction, and CH4 prediction equations based on diets containing linseed resulted in lower prediction accuracy.

Effects of rutin and buckwheat seeds on energy metabolism and methane production in dairy cows.

Flavonoids are secondary plant metabolites with several health promoting effects. As dairy cows often suffer from metabolic imbalance and health problems, interest is growing in health improvements by plant substances such as flavonoids. Our group has recently shown that the flavonoids quercetin and rutin (a glucorhamnoside of quercetin) are bioavailable in cows when given via a duodenal fistula or orally, respectively, affect glucose metabolism, and have beneficial effects on liver health. Furthermore, flavonoids may reduce rumen methane production in vitro through their antibacterial properties. To test the hypothesis that rutin has effects on energy metabolism, methane production, and production performance in dairy cows, we fed rutin trihydrate at a dose of 100mg/kg of body weight to a group of 7 lactating dairy cows for 2 wk in a crossover design. In a second experiment, 2 cows were fed the same ration but were supplemented with buckwheat seeds (Fagopyrum tartaricum), providing rutin at a dose comparable to the first experiment. Two other cows receiving barley supplements were used as controls in a change-over mode. Blood samples were taken weekly and respiration measurements were performed at the end of each treatment. Supplementation of pure rutin, but not of rutin contained in buckwheat seeds, increased the plasma quercetin content. Methane production and milk yield and composition were not affected by rutin treatment in either form. Plasma glucose, ß-hydroxybutyrate, and albumin were increased by pure rutin treatment, indicating a possible metabolic effect of rutin on energy metabolism of dairy cows. In addition, we did not show that in vivo ruminal methane production was reduced by rutin. In conclusion, we could not confirm earlier reports on in vitro methane reduction by rutin supplementation in dairy cows in established lactation.

Effects of a 6-wk intraduodenal supplementation with quercetin on energy metabolism and indicators of liver damage in periparturient dairy cows.

Periparturient dairy cows experience metabolic challenges that result in a negative energy balance (EB) and a range of postpartum health problems. To compensate for the negative EB, cows mobilize fatty acids from adipose tissues, which can lead to fatty liver disease, a periparturient metabolic disorder. Flavonoids, such as quercetin (Q), are polyphenolic substances found in all higher plants and have hepatoprotective potential and the ability to prevent or reduce lipid accumulation in the liver. In ruminants, few studies on the metabolic effects of Q are available, and thus this study was conducted to determine whether Q has beneficial effects on EB, lipid metabolism, and hepatoprotective effects in periparturient dairy cows. Quercetin was supplemented intraduodenally to circumvent Q degradation in the rumen. Cows (n=10) with duodenal fistulas were monitored for 7wk. Beginning 3wk before expected calving, 5 cows were treated with 100mg of quercetin dihydrate per kilogram of body weight daily in a 0.9% sodium chloride solution for a total period of 6wk, whereas the control cows received only the sodium chloride solution. The plasma flavonoid levels were higher in the Q-treated cows than in the control cows. A tendency for higher postpartum (pp) than antepartum (ap) plasma flavonoid levels was observed in the Q-treated cows than in the controls, which was potentially caused by a reduced capacity to metabolize Q. However, the metabolic status of the Q-treated cows did not differ from that of the control cows. The pp increases in plasma aspartate aminotransferase and glutamate dehydrogenase activities were less in the Q-treated cows than in the control cows. The Q had no effect on energy expenditures, but from ap to pp the cows had a slight decline in respiratory quotients. Irrespective of the treatment group, the oxidation of fat peaked after calving, suggesting that the increase occurred because of an increased supply of fatty acids from lipomobilization. In conclusion, supplementation with Q resulted in lower pp plasma aminotransferase and glutamate dehydrogenase, which indicated reduced liver damage. However, the direct effects of Q on the liver and the implications for animal performance remain to be investigated.

Reduced AgRP activation in the hypothalamus of cows with high extent of fat mobilization after parturition.

Agouti-related protein (AgRP), produced by neurons located in the arcuate nucleus of the hypothalamus stimulates feed intake. During early lactation dairy cows increase their feed intake and additionally mobilize their fat reserves leading to increased plasma non-esterified fatty acid (NEFA) concentrations. Since cows with a higher extent of fat mobilization exhibit the lower feed intake, it seems that high NEFA concentrations confine hyperphagia. To test the involvement of AgRP neurons, we investigated 18 cows from parturition until day 40 postpartum (pp) and assigned the cows according to their NEFA concentration on day 40pp to either group H (high NEFA) or L (low NEFA). Both groups had comparable feed intake, body weight, milk yield, energy balance, plasma amino acids and leptin concentrations. Studies in respiratory chambers revealed the higher oxygen consumption and the lower respiratory quotient (RQ) in H compared to L cows. mRNA abundance of neuropeptide Y, peroxisome proliferator-activated receptor-gamma, AMP-activated protein kinase, and leptin receptor in the arcuate nucleus were comparable between groups. Immunohistochemical studies revealed the same number of AgRP neurons in H and L cows. AgRP neurons were co-localized with phosphorylated adenosine monophosphate-activated kinase without any differences between groups. The percentage of cFOS-activated AgRP neurons per total AgRP cells was lower in H cows and correlated negatively with oxygen consumption and NEFA, positively with RQ, but not with feed intake. We conclude that AgRP activation plays a pivotal role in the regulation of substrate utilization and metabolic rate in high NEFA dairy cows during early lactation.

Studies on persisting effects of soy-based compared with amino acid-supplemented casein-based diet on protein metabolism and oxidative stress in juvenile pigs.

Juvenile growing pigs were studied to explore whether a soy-based diet can induce persistent physiological alterations, especially in protein and energy metabolism, nutrient oxidation and redox homeostasis. In former studies we have shown that in juvenile pigs chronically fed protein diets based on either casein (CAS) or soy protein isolate (SPI), the SPI diet significantly decreases growth rate and increases oxidative stress responsiveness as compared to CAS. In addition, here we show that chronic feeding of SPI vs. CAS diet decreases whole body protein synthesis (WBPS) (p = 0.007) and hepatic gene expression associated with protein synthesis. To study persistent SPI effects, a three-period feeding experiment was designed: In the test group 18 pigs received the CAS diet for 24 days (period 1), followed by 31 days on the SPI diet (period 2) and further 31 days on the CAS diet (period 3). In the control group 18 pigs were fed the CAS diet throughout the three periods (86 days). Temporary consumption of SPI diet results in persistent changes of protein metabolism and oxidative stress responsiveness. After switching back from SPI to CAS diet the decrease of WBPS of the test group vs. control group was of borderline significance (p = 0.061), transcript levels of hepatic gene expressions of leucine aminopeptidase, endopeptidase 24.16, glutathione-S-transferase and peptide methionine sulfoxide reductase were increased. In liver tissue, total glutathione was increased and thiobarbituric acid reactive substances were decreased in the test vs. control group. In conclusion, results suggest that SPI-induced changes in protein and amino acid metabolism as well as in redox homeostasis and antioxidative potential in growing pigs persist 4 weeks after the cessation of SPI feeding.