One-carbon metabolite supplementation to heifers for the first 14 d of the estrous cycle alters the plasma and hepatic one-carbon metabolite pool and methionine-folate cycle enzyme transcript abundance in a dose-dependent manner.

The objective of this study was to determine the dose of folate and vitamin B12 in beef heifers fed rumen protected methionine and choline required to maintain increased B12 levels and intermediates of the methionine-folate cycle in circulation. Angus heifers (n = 30; BW = 392.6 ±â€…12.6 kg) were individually fed and assigned to one of five treatments: 0XNEG: Total mixed ration (TMR) and saline injections at day 0 and 7 of the estrous cycle, 0XPOS: TMR, rumen protected methionine (MET) fed at 0.08% of the diet DM, rumen protected choline (CHOL) fed at 60 g/d, and saline injections at day 0 and 7, 0.5X: TMR, MET, CHOL, 5 mg B12, and 80 mg folate at day 0 and 7, 1X: TMR, MET CHOL, 10 mg vitamin B12, and 160 mg folate at day 0 and 7, and 2X: TMR, MET, CHOL, 20 mg B12, and 320 mg folate at day 0 and 7. All heifers were estrus synchronized but not bred, and blood was collected on day 0, 2, 5, 7, 9, 12, and 14 of a synchronized estrous cycle. Heifers were slaughtered on day 14 of the estrous cycle for liver collection. Serum B12 concentrations were greater in the 0.5X, 1X, and 2X, compared with 0XNEG and 0XPOS on all days after treatment initiation (P < 0.0001). Serum folate concentrations were greater for the 2X treatment at day 5, 7, and 9 of the cycle compared with all other treatments (P ≤ 0.05). There were no differences (P ≥ 0.19) in hepatic methionine-cycle or choline analyte concentrations by treatment. Concentrations of hepatic folate cycle intermediates were always greater (P ≤ 0.04) in the 2X treatment compared with the 0XNEG and 0XPOS heifers. Serum methionine was greater (P = 0.04) in the 0.5X and 2X heifers compared with 0XNEG, and S-adenosylhomocysteine (SAH) tended (P = 0.06) to be greater in the 0.5X heifers and the S-adenosylmethionine (SAM):SAH ratio was decreased (P = 0.05) in the 0.5X treatment compared with the 0XNEG, 0XPOS, and 2X heifers. The hepatic transcript abundance of MAT2A and MAT2B were decreased (P ≤ 0.02) in the 0.5X heifers compared with the 0XNEG, 0XPOS, and 2X heifers. These data support that beef heifers fed rumen protected methionine and choline require 20 mg B12 and 320 mg folate once weekly to maintain increased concentrations of B12 and folate in serum. Furthermore, these data demonstrate that not all supplementation levels are equal in providing positive responses, and that some levels, such as the 0.5X, may result in a stoichiometric imbalance in the one-carbon metabolism pathway that results in a decreased SAM:SAH ratio.

The strategic inclusion of one-carbon metabolites, which include vitamins and minerals that are found in human prenatal vitamins, to beef cattle feeding and management protocols during the periconceptual period (the time around breeding) is a novel concept. Therefore, this study aimed to identify the feeding and injection doses of one-carbon metabolites in beef heifers to maintain increased circulating concentrations of one-carbon metabolites for use as a model from which other studies could base their treatments on. We determined that daily feeding of methionine and choline at 0.08% of dry matter and 60 g/d, respectively, and administration of vitamin B12 and folate at 20 mg and 320 mg once per week, respectively resulted in sustained elevated concentrations of one-carbon metabolites.

Effects of feeding bulls dried corn distiller's grains plus solubles or CaSO4 on mineral and metabolite concentrations in serum and seminal plasma.

Yearling Angus bulls (n = 36) were assigned one of three diets: 1) 60 % concentrate as corn (CON, 0.2 % S, 13.4 % CP; n = 12); 2) 60 % dried corn distiller's grains plus solubles (60DDGS 0.5 % S, 22.0 % CP; n = 12); 3) CON diet + equivalent sulfur of 60DDGS as CaSO4 (SULF, 0.5 % S, 13.9 % CP; n = 12) to evaluate effects of feeding 60 % DDGS or sulfur as CaSO4 on mineral and metabolite concentrations in serum and seminal plasma. Treatment × day interactions (P < 0.03) were observed for serum Cu, Se, and Mo. For Cu at d 112, lesser (P < 0.01) concentrations were observed in bulls fed the 60DDGS compared to SULF and CON diets. There were greater (P < 0.01) concentrations of Se at d 112 in bulls fed 60DDGS than CON and SULF diets. Concentrations of Mo were greater at d 56 and 112 (P < 0.01) in bulls fed CON compared to SULF and 60DDGS diets. In seminal plasma, there were treatment × day interactions (P < 0.02) for Cu and Mo. For Cu, at d 112, there was a lesser (P < 0.01) concentration in the bulls fed SULF compared to CON and 60DDGS diets. For Mo, there was a greater (P < 0.01) concentration in bulls fed the CON than 60DDGS and SULF diets at d 56 and 112. Changes in mineral and metabolite concentrations may have effects on bull reproductive performance when there is a relatively greater dietary sulfur content.

The effects of nutrient restriction on mRNA expression of endogenous retroviruses, interferon-tau, and pregnancy-specific protein-B during the establishment of pregnancy in beef heifers.

We hypothesize that syncytin-Rum1, bovine endogenous retrovirus-K1 (BERV-K1), pregnancy-specific protein-B (PSP-B), and interferon-τ (IFN-τ) will be influenced by maternal nutrient restriction and be differentially expressed during key stages (day 16, 34, and 50) of the establishment of gestation when fed to meet industry standards. Commercial crossbred heifers (n = 49) were maintained on a total mixed ration and supplemented with dried distillers grains with solubles. All heifers were subjected to 5-d CO-Synch + CIDR estrus synchronization protocol. Non-pregnant, non-bred control (NP-NB) heifers (n = 6) were ovariohysterectomized on day 16, and the remaining heifers were AI to a single Angus sire (day of breeding = day 0). On the day of breeding, heifers were randomly assigned to dietary treatments. One half were assigned to control treatment (CON) targeted to gain 0.45 kg/d, and the remaining half were assigned to restricted treatment (RES), which received 60% of control diets. Heifers were subjected to ovariohysterectomy on day 16, 34, or 50 of gestation. Utero-placental tissues were obtained from the uterine horn ipsilateral (P) and contralateral (NP) to the corpus luteum and separated into maternal caruncle (CAR), maternal endometrium, inter-caruncle, (ICAR), and fetal membrane (FM). There were no interactions between stage of gestation and nutritional treatment for syncytin-Rum1 or PSP-B (P > 0.22). Expression of BERV-K1 was influenced by a treatment × stage of gestation interaction (P = 0.03) in NP-CAR. On day 50, heifers fed the CON diet had greater BERV-K1 expression compared with CON heifers on day 16 and 34 and RES heifers at all sampling time points. There was a treatment × stage of gestation interaction (P < 0.01) for IFN-τ in FM tissue. On 16 d, mRNA expression of IFN-τ was greater (P < 0.01) compared with day 34 and 50 for both CON and RES heifers, but RES FM had greater (P < 0.01) IFN-τ expression compared with CON FM. In P-CAR, PSP-B expression increased (P < 0.01) by 18 000-fold on day 50 compared with NP-NB heifers. In P-ICAR, expression of syncytin-Rum1 in P-ICAR was greater (P = 0.01) on day 16 with a 14.14-fold increase compared with relative expression on day 34 and 50; whereas, PSP-B was increased (P < 0.01) on day 34 and 50 compared with day 16. In conclusion, 40% nutrient restriction had limited influence on mRNA of ERVs, PSP-B, and IFN-τ but stage of gestation differences reinforced the importance of these genes during the establishment of pregnancy.