Bioavailability of Ruminally or Abomasally Infused L-carnitine in Holstein Heifers

This study evaluated the relative bioavailability of carnitine delivered by different methods in dairy cattle. Four Holstein heifers were used in a split-plot design to compare ruminally or abomasally infused L-carnitine. The study included 2 main-plot periods, with infusion routes allocated in a crossover design. Within main-plot periods, each of 3 subplot periods consisted of 4-d infusions separated with 4-d rest periods. Subplot treatments were infusion of 1, 3, and 6 g L-carnitine daily. Doses were increased within a period to minimize carryover. Treatments were delivered in two 10-h infusions daily. Blood was collected before the start of infusions and on day 4 of each infusion to obtain baseline and treatment carnitine concentrations. There was a dose × route interaction (P \u3c 0.05) and route effect (P \u3c 0.01) for increases in plasma carnitine above baseline, with increases above baseline being greater across all dose levels when infused abomasally compared to ruminally. Results demonstrated superior bioavailability of carnitine when ruminal exposure was physically bypassed

Bioavailability of Rumen-Protected Carnitine in Lactating Dairy Cows

For this study, 56 lactating Holstein cows (143 ± 72 days in milk) were used in a randomized complete block design to evaluate 2 rumen-protected products compared to crystalline carnitine. Treatments were a) control, b) 3 grams/day crystalline L-carnitine (raw), c) 6 grams/day raw, d) 5 grams/day 40COAT (40% coating, 60% L-carnitine), e) 10 grams/day 40COAT, f) 7.5 grams/day 60COAT (60% coating, 40% L-carnitine), and g) 15 grams/day 60COAT. Treatments were top-dressed to diets twice daily. The 14-day experiment included a 6-day baseline-measurement period with the final 2 days used for data and sample collection and an 8-day treatment period with the final 2 days used for data and sample collection. Plasma, urine, and milk samples were analyzed for L-carnitine. Crystalline (P \u3c 0.001) and 40COAT (P = 0.01) linearly increased plasma L-carnitine, and 60COAT tended to linearly increase plasma L-carnitine (P = 0.08). Total daily excretion (milk + urine) of L-carnitine averaged 1.52 ± 0.04 grams in controls, increased linearly with crystalline and 40COAT, and increased quadratically with 60COAT (all P \u3c 0.05). Crystalline increased plasma L-carnitine and milk + urine L-carnitine more than 40COAT and 60COAT (all P \u3c 0.05). Carnitine supplementation increased carnitine concentrations in plasma, milk, and urine; however, the rumen protection did not provide additional increases in concentration

Effects of Dietary Supplementation of Scutellaria baicalensis Extract During Early Lactation on Milk Production of Dairy Cattle

Multiparous Holstein cows (n = 122) were used in a randomized block design to determine the effect of short-term and long-term postpartum administration of Scutellaria baicalensis extract (SBE) on 305-day milk yield, 120-day milk component yield, and early lactation milk markers of inflammation and metabolic function. Treatments were (1) control, (2) short-term (5-day) administration of the SBE (SBE5), and (3) longterm (60-day) administration of the SBE (SBE60). Treatments were included in a treatment pellet that was identical to the control pellet in ingredient source and composition except for the extract, and both pellets were provided via an automated milking system. Milk samples were collected on day 1, 3, and once during days 5–12 of lactation, followed by weekly sampling for the remainder of the 120 days collection period. Milk samples collected in the first 2 weeks were used for biomarker analysis (haptoglobin and β-hyroxybutyrate [BHBA]), and all samples were used for composition analysis. Cows were scored for body condition every 2 weeks prepartum and postpartum. Milk production, programmed pellet allocation, and actual provision of both pelleted feeds were recorded daily. There was no difference in daily treatment pellet feeding between SBE5 and SBE60 for the first 5 days of lactation. Total pellet intake was greater for SBE60 than SBE5 and control cows during the treatment period (weeks 1–9), but not during the carryover period (weeks 10–36). No treatment effects were observed for body condition, milk haptoglobin, or milk BHBA. Whole-lactation milk yield was increased for SBE60 compared to control, but SBE5 did not differ from control. Milk lactose and fat yields were significantly greater and milk protein yield tended to be greater for SBE60 than control. Treatment SBE60 decreased somatic cell count (SCC) compared to control during weeks 3–5 and 8, whereas SBE5 did not affect SCC. Mastitis incidence was lesser for both SBE5 and SBE60 compared to control. Time to pregnancy did not differ, but retention in the herd tended to be greater for SBE60 than control. In conclusion, despite no detected treatment effects on BCS or milk biomarkers of inflammation and metabolic status, supplementation of postpartum dairy cows with Scutellaria baicalensis extract for 60 days was effective at decreasing mastitis incidence and increasing milk yield

Impact of Saccharomyces cerevisiae Fermentation Product on Feed Intake Parameters, Lactation Performance, and Metabolism of Transition Dairy Cattle

A Saccharomyces cerevisiae fermentation product (NutriTek; Diamond V, Cedar Rapids, IA) was fed from 29 ± 5 days before calving and through 42 days in milk (DIM) to evaluate the effects on feed intake parameters, milk production, and metabolism. Treatments were control (n = 30) or 18 g/d NutriTek (NT, n = 34) provided as total mixed rations. Cows were individually fed 3×/day prepartum and 2×/day postpartum. Cows were milked 2×/day with samples taken 2×/week for composition analysis. Body weight (BW) was measured at enrollment (day -29 ± 5), day 0, and day 42 relative to calving, and body condition was scored weekly. Blood samples were collected during weeks -4, -2, 1, 2, and 5 relative to calving for biomarkers of metabolism and inflammation. To evaluate adaptive immunity, cows were challenged with a subcutaneous injection of ovalbumin (egg protein) and immune response was determined by serum concentrations of anti-ovalbumin immunoglobulin G (IgG) on days 7, 21, 28, and 35 of lactation. Overall dry matter intake, BW, body condition score, and milk yield were not different between treatments. NutriTek did alter feeding behavior by increasing the number of meals consumed with less time between those meals. Milk fat concentration increased with NT during weeks 4 and 5 of lactation, which contributed to an increase in fat yield during those weeks. There were tendencies for greater milk lactose yield in control cows and greater milk urea nitrogen concentration in NT, but no treatment differences for milk protein concentration or somatic cell count. Assuming equal digestibility, energy balance was more negative for NT during weeks 4 and 5, mirroring the increase in milk fat during that time. Energy density of diets calculated from observed ECM yield and BW change did not differ by treatment. Plasma concentrations of free fatty acids, β-hydroxybutyrate (BHB), glucose, insulin, and the inflammation marker haptoglobin did not differ between treatments. NutriTek increased the incidence of subclinical ketosis (12 vs. 38%, diagnosed by urine ketones). There was no overall treatment effect for immune response to vaccination; however, a treatment × parity interaction indicated greater antibody concentration in primiparous cows supplemented with NT. A partial budget analysis accounting for milk income, feed cost, and expense associated with ketosis treatment indicated an additional $0.35 daily profit per cow for NT vs. control. In conclusion, NT supplementation during the transition period altered feeding behavior and milk fat concentration and ultimately appeared profitable in this scenario, despite the increased incidence of subclinical ketosis and a lack of response in early lactation milk yield

Productivity of a Triticale and Crimson Clover Winter Cover Crop for Dairies

The potential for a winter cover crop to align with agronomic objectives and to support milk production was evaluated at the Kansas State University Dairy Teaching and Research Center, Manhattan, KS. August planting of a triticale and crimson clover blend following corn silage harvest resulted in production of more than 3.5 tons of dry matter prior to subsequent corn planting. After ensiling, the impact of triticale/crimson clover silage (TCS) on milk production was evaluated in 48 mid- to late-lactation Holstein cows. Cows were blocked by parity (1 and 2+) and milk production, then randomly assigned within block to treatment sequence and pen. The crossover design consisted of two 21-day periods, with 17 days of diet adaptation and 4 days of sampling. Treatments were a diet which included TCS at 15% of diet dry matter (DM) and a control ration in which TCS was primarily replaced by alfalfa and grass hays. The TCS diet included additional bypass soybean meal in an attempt to balance metabolizable protein supply across diets. Samples of rations, feed refusals, and milk were obtained daily, and milk yield was recorded. The TCS diet decreased dry matter intake (48.4 vs. 55.9 ± 3.4 lb/d; P = 0.02), but did not alter milk yield (P = 0.97); therefore, feed efficiency was greater for the TCS diet (P = 0.04). Milk fat concentration tended to increase on the TCS diet (P \u3c 0.10) whereas milk lactose yield tended to be lesser for TCS (P = 0.09), but other milk components analyzed (milk protein, MUN, SCC) did not differ between diets (P \u3e 0.15). Utilization of TCS also impacted the dairy’s nutrient management plan, as the winter forage harvest removed 40 and 340 lb/a of phosphorus and potassium, respectively. Overall, the blend of triticale and crimson clover as a winter cover crop produced good quality silage that maintained high milk production while also removing key nutrients from the soil to benefit nutrient management planning