Effects of an exogenous enzyme preparation extracted from a mixed culture of Aspergillus spp. on lactational performance, metabolism, and digestibility in primiparous and multiparous cows

The objective of this study was to investigate the effects of an exogenous enzyme preparation from As-pergillus oryzae and Aspergillus niger on lactational performance of dairy cows. Forty-eight Holstein cows (32 primiparous and 16 multiparous) averaging (+/- SD) 36.3 +/- 8.7 kg/d milk yield and 141 +/- 52 d in milk were enrolled in a 10-wk randomized complete block design experiment (total of 24 blocks) and assigned to 1 of 2 treatments: basal diet, no enzyme supplementation (CON) or the basal diet supplemented with 4.2 g/kg dry matter intake (DMI) of an exogenous enzyme prep-aration containing amylolytic and fibrolytic activities (ENZ). After a 2-wk covariate period, premixes with the enzyme preparation or control were top-dressed daily by mixing with approximately 500 g of total mixed ra-tion. Production data were collected daily and averaged by week. Milk samples were collected every other week, and milk composition was averaged by week. Blood, fe-cal, and urine samples were collected over 2 consecutive days at 0, 4, 8, 12, and 36 h after feeding during the last week of the experiment. Compared with CON, cows fed ENZ tended to increase DMI and had increased milk concentrations of true protein, lactose, and other solids. Milk fat content tended to be higher in CON cows. A treatment x parity interaction was found for some of the production variables. Primiparous cows receiv-ing ENZ had greater yields of milk, energy-corrected milk, milk true protein, and lactose compared with CON primiparous cows; these production variables did not differ between treatments for multiparous cows. Intake and total-tract digestibility of nutrients did not differ between treatments. Concentrations of blood glucose and total fatty acids were not affected by ENZ supplementation, but 0-hydroxybutyrate concentration tended to be greater in ENZ cows. Overall, the exog-enous enzyme preparation used in this study increased milk protein and lactose concentrations in all cows, and milk production in primiparous but not multiparous cows. The differential production response between pri-miparous and multiparous cows was likely a result of a greater increase in DMI with ENZ supplementation in the younger animals.Peer reviewe

Effects of Medium Chain Fatty Acid Application in Swine Feed on Porcine Epidemic Diarrhea Virus

Medium chain fatty acid (MCFA) application has been identified as a promising strategy to decrease viral pathogen transmission in swine feed. Four experiments were conducted to: 1) determine if MCFAs are effective when applied to feed both prior to and after porcine epidemic diarrhea virus (PEDV) inoculation measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR), 2) evaluate the effects of varying amounts and combinations of MCFA measured by qRT-PCR, and 3) evaluate selected MCFA treatments in a bioassay. In Exp. 1, treatments were arranged in a 2 × 2 + 1 factorial with the main effects of chemical treatment (0.3% Sal CURB [Kemin Industries, Des Moines, IA] or 1% MCFA blend of 1:1:1 C6:C8:C10 [PMI, Arden Hills, MN]) and timing of chemical treatment (pre or post-inoculation with PEDV), plus a positive control (feed inoculated with PEDV and no chemical treatment). Feed was treated with the respective treatment either before or after inoculation at which point it remained at ambient temperature for 24 h and then was analyzed via qRT-PCR. The analyzed values represent cycle threshold (Ct), for which a lower number indicates greater detection of viral nucleic acid. Results demonstrated that all combinations of chemical treatment and timing increased Ct compared to the positive control (P \u3c 0.05). Additionally, treatment of feed pre-PEDV inoculation resulted in increased Ct value compared to post- inoculation treatment (P = 0.009) and Sal CURB increased Ct in comparison with 1% MCFA (P \u3c 0.0001). In Exp. 2, the chemical treatments were applied pre-inoculation and consisted of:1) positive control, 2) 0.3% Sal CURB, 3) 0.125% C6, 4) 0.25% C6, 5) 0.33% C6,6) 0.125% C8, 7) 0.25% C8, 8) 0.33% C8, 9) 0.125% C10, 10) 0.25% C10, 11) 0.33% C10, 12) 0.125% C5, 13) 0.25% C5, 14) 0.33% C5, and 15) 0.66% C5, which were analyzed via qRT-PCR. Treatment of feed with 0.33% C8 resulted in increased (P \u3c 0.05) Ct values compared to all other levels of MCFA and the positive control feed. Further, Sal CURB, 0.25% C6, 0.33% C6, all levels of C8, 0.25% C10, 0.33% C10, or 0.66% C5 all had increased Ct values compared to positive control feed (P \u3c 0.05). Increasing amounts of each individual MCFA resulted in increased Ct (P \u3c 0.045). In Exp. 3, the chemical treatments were applied pre-inoculation and consisted of: 1) positive control; 2) 0.3% Sal CURB; 3) 0.25% MCFA blend; 4) 0.375% MCFA blend; 5) 0.500% MCFA blend; 6) 0.750% MCFA blend; 7) 1.0% MCFA blend; 8) 0.125% C6 + 0.125% C8; 9) 0.25% C6 + 0.25% C8; 10) 0.33% C6 + 0.33% C8; 11) 0.125% C6 + 0.125% C10; 12) 0.25% C6 + 0.25% C10; 13) 0.33% C6 + 0.33% C10; 14) 0.125% C8 + 0.125% C10; 15) 0.25% C8 + 0.25% C10; and 16) 0.33% C8 + 0.33% C10, which were analyzed via qRT-PCR. Treating feed with Sal CURB, 0.500% blend, 0.750% blend, 1.0% blend, all levels of the C6 + C8, 0.25% C6 + 0.25% C10, 0.33% C6 + 0.33% C10, 0.25% C8 + 0.25% C10, or 0.33% C8 + 0.33% C10 resulted in increased Ct compared to the positive control (P \u3c 0.05). Lastly, in Exp. 4, feed was treated pre-inoculation with either 1) no treatment (positive control); 2) 0.3% Sal CURB; 3) 0.5% MCFA blend; or 4) 0.3% C8 and samples were analyzed via qRT-PCR and bioassay. Adding either 0.5% MCFA blend or 0.3% C8 resulted in increased Ct compared to the positive control. Further, only the positive control resulted in a positive in vivo bioassay. This set of experiments demonstrates that MCFA and Sal CURB are effective at decreasing detection of PEDV in feed both prior to and post-inoculation. Additionally, inclusion of lower levels of MCFA than previously evaluated may provide protection against PEDV transmission through feed