László Wágner

Effects of rumen-protected choline supplementation on milk production and choline supply of periparturient dairy cows.

The objective of the present study was to determine the effects of rumen-protected choline (RPC) supplementation on body condition, milk production and milk choline content during the periparturient period. Thirty-two Holstein cows were allocated into two groups (RPC group - with RPC supplementation, and control group - without RPC supplementation) 28 days before the expected calving. Cows were fed the experimental diet from 21 days before expected calving until 60 days of lactation. The daily diet of the RPC group contained 100 g of RPC from 21 days before calving until calving and 200 g RPC after calving for 60 days of lactation, which provided 25 g and 50 g per day choline, respectively. Body condition was scored on days -21, 7, 35 and 60 relative to calving. Milk production was measured at every milking; milk fat, protein and choline content were determined on days 7, 35 and 60 of lactation. Body condition was not affected by RPC supplementation. Milk yield was 4.4 kg higher for the group of cows receiving supplementary choline during the 60 days experimental period and 4% fat-corrected milk production was also increased by 2.5 kg/day. Milk fat content was not altered by treatment, but fat yield was increased by 0.10 kg/day as a consequence of higher milk yield in the RPC-treated group. Milk protein content tended to increase by RPC supplementation and a 0.18 kg/day significant improvement of protein yield was detected. Milk choline content increased in both groups after calving as the lactating period advanced. However, milk choline content and choline yield were significantly higher in the RPC group than in the control group. The improved milk choline and choline yield provide evidence that some of the applied RPC escaped ruminal degradation, was absorbed from the small intestine and improved the choline supply of the cows and contributed to the changes of production variables.

Composition of diet modifies colonization dynamics of Campylobacter jejuni in broiler chickens

To evaluate the impact of diet composition on colonization dynamics of Camp. jejuni and on related physiological parameters in the chicken intestine.

Effect of various dietary fat supplementations on liver lipid and glycogen of high-yielding dairy cows in the peripartal period

In a model experiment, Holstein-Friesian dairy cows were fed on a corn-silage-based diet supplemented with 11.75 MJ NE1 per day of calcium soaps of palm oil fatty acids (CAS) or hydrogenated triglyceride (HTG) or without fat supplementation (control). All diets were fed to the cows over a period from 21 +/- 3 days (d) prior to the expected calving to d 100 +/- 5 postpartum. On d 25 (basal sample) and d 14 prepartum as well as on d 5 and 25 postpartum liver samples were collected by percutaneous biopsy. Total lipid content, fatty acid composition and glycogen of liver tissues were determined. At d 5 postpartum, both control and CAS cows had higher liver lipid (P < 0.05) and lower glycogen (P < 0.05) concentrations than cows in the HTG group. No significant (P < 0.05) differences were detected in liver fat content among the groups at d 14 prepartum or d 25 postpartum. The glycogen concentration slightly decreased in the liver of cows in each treatment group from d 14 prepartum to d 5 postpartum; however, this decrease was more intensive in both the control and CAS groups than in the HTG group. The variations in liver lipid concentrations were accompanied by significant changes in the proportion of C16:0, C16:1n-7, C18:0, C18:1n-9, C18:2n-6 and C20:4n-6 fatty acids in the liver lipids. The results show that HTG supplementation exerted more advantageous effects on liver lipid and glycogen metabolism than did CAS supplementation.

Effect of feeding different oils on plasma corticosterone in broiler chickens

A study was conducted to examine the effects of different oils on the plasma corticosterone concentrations of broiler chickens fed ad libitum or deprived of feed for 24 hours. A total of 36 Ross broilers were randomly assigned to one of three dietary treatments at 10 days of age and fed a grower diet supplemented with 60 g/kg soybean oil (rich in linoleic acid, C18:2n-6), linseed oil (rich in a-linolenic acid, C18:3n-3) or fish oil (rich in C14:0, C16:0, C16:1n-7, C20:1n-9; eicosapentaenoic acid and docosahexaenoic acid, EPA, C20:5n-3 and DHA, C22:6n-3), respectively, for 18 days. Dietary supplementation of fish oil resulted in lower (P < 0.05) baseline plasma corticosterone levels of chickens fed ad libitum for 18 days compared to soybean and linseed oil supplementations. Feed deprivation for 24 h induced a significant (P < 0.05) increase in corticosterone concentration in every treatment group compared to the ad libitum-fed birds. The hormone levels of feed-deprived birds did not differ significantly among groups fed diets supplemented with different oils.

Nutritional modulation of intestinal drug-metabolizing cytochrome P450 by butyrate of different origin in chicken

Intestinal cytochrome P450 (CYP) enzymes play key role in the first pass metabolism of orally ingested xenobiotics, providing a primary metabolic barrier, being of special importance in maintaining animal health and production. This study was aimed to investigate how intestinal drug-metabolizing CYPs can be modulated by nutritional factors in broiler chicken. We investigated the effects of the natural growth promoter (n-)butyrate of different origin (feed supplementation of protected or non-protected forms and/or inducing caecal microbial production by supporting higher level of dietary non-starch polysaccharides [NSP]) on the activity of duodenal CYPs. To observe the connection between intestinal CYP activity and butyrate concentration, the distribution of differently originated butyrate was also assessed by measuring its concentration in various intestinal segments and different vessels of portal and systemic circulation. Butyrate of different origin showed varying distribution properties as being absorbed from different parts of the gastrointestinal tract. Intestinal CYP1A and CYP2H2 activities were increased by dietary butyrate supplementation and by the increased caecal microbial butyrate production, while CYP3A37 activity was minimally influenced by microbial butyrate only. The present study proved that both dietary and microbial butyrate could alter the activity of CYPs in the duodenal epithelium. Our findings suggest that intestinal CYPs could be induced not only by the intestinal luminal butyrate, but also from basolateral side, by the already absorbed butyrate. Such action of butyrate can be of special importance from food safety and pharmacotherapeutic point of view as it may modify the metabolism and intestinal kinetics of simultaneously applied xenobiotics.