Effects of 1,25-dihydroxycholecalciferol and reduced vitamin D3 level on broiler performance and bone quality

<div><p>ABSTRACT This study was conducted to evaluate the effect of two levels of vitamin D3 with or without 1,25- dihydroxycholecalciferol (1,25(OH)2D3) on live performance and bone quality of broiler chickens. For that, we used a completely randomized design in a 2 × 2 factorial arrangement, with eight replicates of 30 Cobb®500 male broiler chicks each (n = 960). The two levels of vitamin D3 and the addition or not of 0.5 μg 1,25(OH)2D3/kg were considered as main factors. The vitamin D3 levels were: 2500/2000 IU/kg and 1250/1000 IU/kg for the starter (1 to 21 days) and grower (22 to 40 days) phases, respectively, with the first representing the levels used in industry (100%) and the second, a reduction in 50% of those levels. The 1,25(OH)2D3 source was Solanum glaucophyllum. On days 21 and 40, one broiler per replicate was killed and long bones were removed for analyses of mineral percentage, bone mineral density, biomechanical properties, and morphology. No significant differences were found related to vitamin D3 levels and the addition or not of 1,25(OH)2D3 for live performance, mineral percentage, strength, stiffness, and morphology. Toughness was lower when 1,25(OH)2D3 was used at 21 days, but this effect was not observed at 40 days of age. Bone mineral density was greater when 100% of vitamin D3 was used at 40 days of age. The reduction of up to 50% of vitamin D3 levels is sufficient to ensure performance and bone development of broilers at 21 and 40 days of age. The inclusion of 0.5 μg 1,25(OH)2D3/kg in addition to diets with sufficient levels of vitamin D3 shows no effect on the improvement of those parameters at the same ages.</p></div

Mean concentrations of NAR residues analyzed by HPLC-MS/MS in the broiler chicken muscle matrix according to chicken day of age.

<p>Mean concentrations of NAR residues analyzed by HPLC-MS/MS in the broiler chicken muscle matrix according to chicken day of age.</p

Chromatogram of a muscle sample from group C collected at the last day of administration (28 days of age) demonstrating the presence of the 1^st and 2^nd transitions of DNC (A) and NAR (B).

<p>Chromatogram of a muscle sample from group C collected at the last day of administration (28 days of age) demonstrating the presence of the 1^st and 2^nd transitions of DNC (A) and NAR (B).</p

Chromatogram of a muscle sample from group B collected at 25 days of age demonstrating the presence of the 1^st and 2^nd transitions of DNC.

<p>Chromatogram of a muscle sample from group B collected at 25 days of age demonstrating the presence of the 1^st and 2^nd transitions of DNC.</p

Mean concentrations of DNC analyzed by HPLC-MS/MS method in the muscle matrix from broilers that received nicarbazin-medicated feed according to chicken day of age.

<p>Mean concentrations of DNC analyzed by HPLC-MS/MS method in the muscle matrix from broilers that received nicarbazin-medicated feed according to chicken day of age.</p

Transitions, relative intensity of the ions and MS/MS parameters used for each analyte.

<p>Transitions, relative intensity of the ions and MS/MS parameters used for each analyte.</p

Mean concentrations of DNC analyzed by HPLC-MS/MS in the muscle matrix from broilers that received medicated feed with a nicarbazin-narasin combination according to chicken day of age.

<p>Mean concentrations of DNC analyzed by HPLC-MS/MS in the muscle matrix from broilers that received medicated feed with a nicarbazin-narasin combination according to chicken day of age.</p

Representative semi-logarithmic plot of residue concentration in muscle from broiler chickens subjected to a pharmacological treatment with nicarbazin (group B) for DNC vs. time for 99% tolerance level.

<p>Circles represent the residue concentration of DNC for an individual animal. The straight line and the curve represent the regression line (LR) and its 99% tolerance limit with 95% confidence interval, respectively. The withdrawal period calculation based on the MRL (200 μg kg^-1) is plotted with a vertical line.</p

Representative semi-logarithmic plot of residue concentration in muscle from broiler chickens subjected to a pharmacological treatment with nicarbazin + narasin (group C) for DNC vs. time for 99% tolerance level.

<p>Circles represent the residue concentration of DNC for an individual animal. The straight line and the curve represent the regression line (LR) and its 99% tolerance limit with 95% confidence interval, respectively. The withdrawal period calculation based on the MRL (200 μg kg^-1) is plotted with a vertical line.</p

Effects of <i>in ovo</i> injection of bacterial peptides and CpG-ODN on <i>Salmonella enterica</i> serovar Heidelberg infection in specific pathogen-free (SPF) chicks

The increasing prevalence of pathogenic and antimicrobial-resistant isolates of Salmonella Heidelberg (SH) represents a global concern. Consequently, novel strategies for preventing and controlling infections caused by this bacterium are needed. This study aimed to investigate the protective effects of in ovo injection with a formulation based on bacterial peptides, either alone or in combination with oligodeoxynucleotides containing cytosine-phosphodiester-guanine (CpG-ODN), against SH infection in chicks. Genomic data of SH available in public databases were analyzed to select amino acid sequences of structural proteins or those with greater relevance for intestinal colonization. These sequences were subjected to linear epitope prediction tools to identify highly immunogenic peptides. SPF eggs (n = 180) were incubated and injected via the allantoic cavity at day 18 of incubation. Results showed that in ovo injection of peptides + CpG-ODN reduced SH colonization in the caecal content during the first week post-infection, although it did not reduce overall faecal excretion throughout the study. Furthermore, CpG-ODN injection may positively affect intestinal health, as evidenced by reduced crypt depth at 21 dpi and increased villus height at 28 dpi. Levels of secretory IgA did not differ between chicks in any groups, and no detectable SH counts were found in the livers of chicks in any of the infected groups throughout the study. In conclusion, in ovo injection with peptides + CpG-ODN may help reduce caecal colonization by SH in the early stages of infection, but it does not impact total faecal excretion. Additionally, CpG-ODN injection may improve intestinal health parameters in chicks. Peptides + CpG-ODN reduced SH in caeca at the first week post-infection.Administered formulations did not reduce SH-faecal excretion.Levels of intestinal IgA were similar between all groups.CpG-ODN improved some parameters associated with chick intestinal health. Peptides + CpG-ODN reduced SH in caeca at the first week post-infection. Administered formulations did not reduce SH-faecal excretion. Levels of intestinal IgA were similar between all groups. CpG-ODN improved some parameters associated with chick intestinal health.</p