Effects of dietary rumen-protected choline supplementation to periparturient dairy cattle on inflammation and metabolism in mammary and liver tissue during an intramammary lipopolysaccharide challenge.

The objective of this experiment was to examine the effects of supplementation and dose of rumen-protected choline (RPC) on markers of inflammation and metabolism in liver and mammary tissue during an intramammary lipopolysaccharide (LPS) challenge. Parous Holstein cows were blocked by calving month and randomly assigned within block to receive 45 g/d of RPC (20.4 g/d of choline ions; CHOL45), 30 g/d of RPC (13.6 g/d of choline ions; CHOL30), or no RPC (CON) as a top-dress starting 24 d before expected calving until 21 d postpartum. Cows were alternately assigned within treatment group to either receive an intramammary LPS challenge (200 µg in each rear quarter; Escherichia coli O111:B4) or not at 17 DIM (CHOL45, n = 9; CHOL45-LPS, n = 9; CHOL30, n = 11; CHOL30-LPS, n = 10; CON, n = 10; CON-LPS, n = 9). Hepatic and mammary tissues were collected from all cows on d 17 postpartum. Hepatic and mammary tissues were collected at ∼7.5 and 8 h, respectively, after the LPS challenge. An additional mammary biopsy was conducted on LPS-challenged cows (CHOL45-LPS, CHOL30-LPS, and CON-LPS) at 48 h postchallenge. Hepatic and mammary RNA copy numbers were quantified for genes involved in apoptosis, methylation, inflammation, oxidative stress, and mitochondrial function using NanoString technology. Targeted metabolomics was conducted only on mammary tissue samples (both 8 and 48 h biopsies) to quantify 143 metabolites including choline metabolites, amino acids, biogenic amines and derivatives, organic acids, carnitines, and glucose. Hepatic IFNG was greater in CHOL45 as compared with CON in unchallenged cows, suggesting an improvement in type 1 immune responses. Hepatic CASP3 was greater in CHOL45-LPS as compared with CON-LPS, suggesting greater apoptosis. Mammary IL6 was reduced in CHOL30-LPS cows as compared with CHOL45-LPS and CON-LPS (8 and 48 h). Mammary GPX4 and COX5A were reduced in CHOL30-LPS as compared with CON-LPS (8 h), and SDHA was reduced in CHOL30-LPS as compared with CON-LPS (8 and 48 h). Both CHOL30-LPS and CHOL45-LPS cows had lesser mammary ATP5J than CON-LPS, suggesting that dietary RPC supplementation altered mitochondrial function following LPS challenge. Treatment did not affect mammary concentrations of any metabolite in unchallenged cows, and only 4 metabolites were affected by dietary RPC supplementation in LPS-challenged cows. Mammary concentrations of isobutyric acid and 2 acyl-carnitines (C4:1 and C10:2) were reduced in CHOL45-LPS as compared with CHOL30-LPS and CON-LPS. Taken together, reductions in medium- and short-chain carnitines along with an increase in long-chain carnitines in mammary tissue from CHOL45-LPS cows suggests less fatty acid entry into the ß oxidation pathway. Although the intramammary LPS challenge profoundly affected markers for inflammation and metabolism in liver and mammary tissue, dietary RPC supplementation had minimal effects on inflammatory markers and the mammary metabolome.

Effects of dietary rumen-protected choline supplementation to periparturient dairy cattle on inflammation, metabolism, and performance during an intramammary lipopolysaccharide challenge.

Recent studies have suggested that dietary rumen-protected choline (RPC) supplementation can modulate immune function, attenuate inflammation, and improve performance in periparturient dairy cattle; however, this has yet to be evaluated during a mastitis challenge. Therefore, the objective of this study was to examine the effects of supplementation and dose of RPC on metabolism, inflammation, and performance during an intramammary lipopolysaccharide (LPS) challenge. Parous Holstein cows (parity, mean ± SD, 1.9 ± 1.1 at enrollment) were blocked by calving month and randomly assigned within block to receive either 45 g/d of RPC (20.4 g/d of choline ions; CHOL45, n = 18), 30 g/d of RPC (13.6 g/d of choline ions; CHOL30, n = 21), or no RPC (CON, n = 19) as a top-dress starting 24 d before expected calving until 21 d postpartum. Cows were alternately assigned within treatment group to either receive an intramammary LPS challenge (200 µg in each rear quarter; Escherichia coli O111:B4) or not at 17 DIM. Before the challenge, CHOL45 and CHOL30 cows produced 3.4 and 3.8 (±1.2 SED) kg/d more milk than CON, respectively. Dietary RPC supplementation did not mitigate the milk loss associated with the intramammary LPS challenge; however, CHOL45 and CHOL30 cows produced 3.1 and 3.5 (±1.4 SED) kg/d more milk than CON, respectively in the carryover period (22 to 84 DIM). Dietary RPC supplementation enhanced plasma ß-hydroxybutyrate (BHB) concentrations before the LPS challenge, and increased plasma nonesterified fatty acids (NEFA) and acetylcarnitine concentrations during the LPS challenge, potentially reflecting greater adipose tissue mobilization, fatty acid transport and oxidation. Aside from trimethylamine N-oxide and sarcosine, which were increased in CHOL45-LPS as compared with CON-LPS, most other choline metabolite concentrations in plasma were unaffected by treatment, likely because more choline was being secreted in milk. Plasma lactic acid concentrations were decreased in CHOL45-LPS and CHOL30-LPS as compared with CON-LPS, suggesting a reduction in glycolysis or an enhancement in the flux through the lactic acid cycle to support gluconeogenesis. Plasma concentrations of fumaric acid, a byproduct of AA catabolism and the urea cycle, were increased in both choline groups as compared with CON-LPS during the LPS challenge. Cows in the CHOL45 group had greater plasma antioxidant potential before the LPS challenge and reduced plasma methionine sulfoxide concentrations during the LPS challenge compared with CON-LPS, suggesting an improvement in oxidant status. Nevertheless, concentrations of inflammatory markers such as haptoglobin and tumor necrosis factor α (TNFα) were not affected by treatment. Taken together, our data suggest that the effects of dietary RPC supplementation on milk yield could be mediated through metabolic pathways and are unlikely to be related to the resolution of inflammation in periparturient dairy cattle. Lastly, dose responses to dietary RPC supplementation were not found for various economically important outcomes including milk yield, limiting the justification for feeding a greater dietary RPC dose in industry.

The effect of J5 bacterins on clinical, behavioral, and antibody response following an Escherichia coli intramammary challenge in dairy cows at peak lactation.

Vaccination against coliform mastitis has become part of mastitis control programs in the past 3 decades, as a means of reducing the severity of clinical mastitis. Our study objective was to evaluate the effect of 2 commercially available vaccines on clinical, behavioral, and antibody response following Escherichia coli intramammary challenge in cows near peak lactation. Cows (n = 12 per group) were vaccinated with vaccine 1 (V1) or vaccine 2 (V2) at dry-off, 21 d pre-calving, and 14 d post-calving. Twelve cows served as unvaccinated controls (CTL). Cows were challenged with E. coli in a rear quarter at approximately 100 d in milk. Milk samples were collected pre- and post-challenge to enumerate E. coli and determine somatic cell count. Serum was collected before each vaccination and at d 0, 1, 2, 3, 6, 30, and 60 relative to challenge, to study antibody response. Milk IgA and tumor necrosis factor-α concentrations were determined in whey. Vaginal temperature, cow activity, and milk yield and components were monitored post-challenge. Bacterial count, somatic cell score, milk yield and component decline, vaginal temperature, activity measures, and antibody and cytokine response were analyzed for treatment differences. The effects of parity, breed, and a repeated measure of time were also tested. Seven cows had to be removed from the study post-challenge for antibiotic treatment (CTL and V1, n = 3 each; V2, n = 1), 2 of which were euthanized (both CTL). Vaccinated cows exhibited fever (vaginal temperature ≥39.4°C) 3 h earlier than CTL cows, but we found no differences between treatments for bacterial count, somatic cell score, or milk yield reduction. Vaccinated cows spent more time lying per rest bout 2 d post-challenge, but total daily lying time was not different from CTL cows during the 7 d post-challenge. The vaccines differed in antibody response: V1 cows had greater serum IgG1 and IgG2 post-challenge. A parity effect was also evident: primiparous cows had lower bacterial counts, somatic cell score and a smaller milk yield decline than multiparous cows, but also had lower antibody production. Immunization with either J5 bacterin did not reduce clinical signs of mastitis in cows challenged at 100 d in milk, demonstrating that the effects of J5 vaccination had diminished at peak lactation.