Potential benefits of early-life supplementation of liquid feed with fennel (Foeniculum vulgare) seeds or oregano (Origanum vulgare) leaves on growth, health, and blood metabolites in Holstein dairy calves.

This study was performed to determine the early-life (first month of age) supplementation of liquid feed with fennel seed powder (FSP) or oregano leaf powder (OLP) on growth performance, health, and blood biochemical attributes in preweaning dairy calves. Holstein female calves (n = 57; 1 d of age; 34.1 ± 0.97 kg of BW; mean ± SE) were assigned randomly to receive liquid feed (colostrum and milk) with no added herbal plants (CON) or supplemented with FSP (3 g/d) or OLP (30 g/d) during the first month of age. The calves received pooled colostrum (4.5 kg/d on the first 2 d of life; total solids = 25.0% ± 1.24; mean ± SD) and then pooled waste milk (6 kg/d from d 3 to 44, 5 kg/d from d 45 to 46, 4 kg/d from d 47 to 48, and 3 kg/d from d 49 to 50 of the trial; total solids = 12.54% ± 0.50) to ensure they receive same mixed liquid feed daily. The calves had unlimited access to the starter feed and fresh water and remained in the study until weaning on d 51 of age. The average mean temperature-humidity index was 70.1 units (ranging between 61.9 to 78.2) during the experiment, indicating a borderline degree of environmental heat-load. The amount of starter feed offered and refused was recorded daily. The calves were weighed immediately after birth and every 10 d thereafter, before the morning feeding. Jugular blood samples were taken immediately before and 24 h after colostrum feeding, at first month of age, and at weaning to quantify serum concentrations of glucose, urea N, cholesterol, triglycerides, total proteins, albumin, globulin, aspartate transferase, alanine transferase, total antioxidant status, and malondialdehyde. Health checks including rectal temperature, general appearance (on a 1-5 score system), fecal score (on a 1-5 score system), and bovine respiratory disease (BRD; scored using the University of Wisconsin Calf Health Chart) were performed daily, by a veterinarian who was unaware of the calf treatment allocations, for all calves over the study period. A repeated-measures ANOVA was used to compare growth performance and blood metabolites among treatment groups, and a logistic regression model using a binomial distribution (PROC GLIMMIX, SAS v. 9.4, SAS Institute Inc.) was used to assess the chance of elevated rectal temperature (≥39.4°C), general appearance (≥2), diarrhea (≥3), and BRD. A Poisson regression model (PROC GENMOD) was also used to test group differences in the experience of days with elevated rectal temperature and general appearance, and frequency and duration of diarrhea or BRD. Total nutrient intake (DM, CP, and ME, but not ether extract) originating from milk and starter feed was greater in OLP- (but not FSP-) supplemented calves compared with CON group, being partially associated with difference in milk refusal. Calves receiving FSP and OLP had greater average daily gain, BW gain, skeletal gain (withers height or heart girth, respectively), and feed efficiency compared with CON animals with no difference between FSP and OLP. Rectal temperature was lower in FSP- (but not OLP-) supplemented calves compared with CON animals. The CON animals had a greater chance of experiencing higher rectal temperature (≥39.4°C; odds ratio = 1.55 and confidence interval = 1.12-2.15 and odds ratio = 1.33 and confidence interval = 0.92-1.90, respectively, compared with FSP and OLP) and general appearance (≥2; odds ratio = 1.99 and confidence interval = 1.45-2.74 and odds ratio = 1.45 and confidence interval = 1.03-2.05), and diarrhea (odds ratio = 1.47 and confidence interval = 1.11-1.97 and odds ratio = 1.49 and confidence interval = 1.07-2.08) compared with those receiving FSP or OLP; with the chance of BRD being lower in FSP- (but not OLP-) supplemented versus CON animals (odds ratio = 1.59 and confidence interval = 1.13-2.23). As compared with OLP and CON groups, FSP treatment resulted in shorter days with elevated rectal temperature and general appearance. Supplementing FSP or OLP decreased the duration of diarrhea and BRD but not their frequency compared with CON. Duration of diarrhea was not different between FSP- or OLP-supplemented calves but calves supplemented with FSP had shorter days with BRD compared with OLP-supplemented calves. Of the blood constituents measured on d 30, concentration of aspartate transferase was higher in FSP- (but not CON) versus OLP-supplemented calves, indicating a transient liver tissue damage or dysfunction which was subsequently ameliorated. At weaning, blood concentration of triglycerides was higher in FSP and OLP groups compared with CON group. Supplementation of the liquid feed with FSP or OLP, especially FSP, had beneficial effects on calf growth performance and health. Further experiments are warranted for optimizing the dosage and duration of feeding FSP or OLP as feed additives for dairy calves.

Essential oils improved weight gain, growth and feed efficiency of young dairy calves fed 18 or 20% crude protein starter diets.

The objective was to evaluate interactions between starter protein (180 vs. 200 g/kg, DM basis) and a mixture of essential oils (EOs; containing thymol, eugenol, vanillin, limonene and guaiacol) on growth, metabolic and ruminal functions of Holstein dairy calves. In a completely randomized 2 × 2 factorial design, 48 calves, 3 days old (averaging BW 42.7 ± 1.9 kg), were allocated into groups fed the following diets: (i) 180 g/kg CP with no EO (180P-NEO); (ii) 180 g/kg CP with EO (180P-EO); (iii) 200 g/kg CP with no EO (200P-NEO); and (iv) 200 g/kg CP with EO (200P-EO). The EO was supplemented as 1 g/kg of starter DM. Calves were fed ad libitum starter diet and were weaned at day 59 of age, but diets continued until day 80. There were no interactive effects of CP and EO on intake and growth. Pre-weaning feed efficiency tended to be increased for 200P-EO (p = .09). Average daily gain and feed efficiency during pre-weaning period as well as weaning weight were increased (p < .05) by EO, whereas wither height was increased by EO (p = .03) and tended to be increased for 200P vs. 180P (p = .06). Post-weaning blood urea nitrogen concentration tended to be lower in 180P vs. 200P (p = .08). Ruminal short-chain fatty acids concentration was greatest in 200P-EO. The EO increased both butyrate (p = .02) and propionate proportions (p = .01) and reduced acetate proportional ratio (p < .01). Ruminal ammonia-N was tended to be lower in calves-fed EO (p = .05) and was lower in those fed 180P vs. 200P (p < .01). In conclusion, supplementation of the starter diet with essential oil improved weight gain, growth and feed efficiency of dairy calves, irrespective of dietary protein content.

Role of antigen-specific regulatory CD4+CD25+ T cells in tolerance induction after neonatal IP administration of AAV-hF.IX.

Neonatal AAV8-mediated Factor IX (F.IX) gene delivery was applied as a model for exploring mechanisms of tolerance induction during immune ontogeny. Intraperitoneal delivery of AAV8/ Factor IX (hF.IX) during weeks 1-4 of life, over a 20-fold dose range, directed stable hF.IX expression, correction of coagulopathy in F.IX-null hemophilia B mice, and induction of tolerance to hF.IX; however, only primary injection at 1-2 days of life enabled increasing AAV8-mediated hF.IX expression after re-administration, due to the absence of anti-viral capsid antibodies. Adoptive splenocyte transfer from tolerized mice demonstrated induction of CD4(+)CD25(+) T regulatory (T(reg)) populations that specifically suppressed anti-hF.IX antibody responses, but not responses to third party antigen. Induction of hF.IX antibodies was only observed in tolerized mice after in vivo CD4(+)CD25(+) cell depletion and hF.IX challenge. Thus, primary injection of AAV during a critical period in the first week of life does not elicit antiviral responses, enabling re-administration of AAV and augmentation of hF.IX levels. Expansion of hF.IX-specific CD4(+)CD25(+) T(regs) has a major role in tolerance induction early in immune ontogeny. Neonatal gene transfer provides a useful approach for defining the ontogeny of immune responses and may suggest approaches for inducing tolerance in the context of genetic therapies.