Tropical animal health and production最新文献

Gastrointestinal infections significantly impact sheep health and productivity, with diarrhea and parasites particularly threatening lambs. To address these challenges, feed additives offer solutions to enhance animal health and performance. This study aimed to investigate the effects of humic acids (HA) on the gastrointestinal tract and growth of lambs. Forty 1/2 Hampshire Down weaned lambs (aged 100.9 ± 7.1 days; average weight 24.4 ± 3.9 kg) were randomly allocated to two groups (20 each), balanced for weight and sex. The control group (CG) received a basal diet without HA supplementation, while the treatment group (TG) was fed a basal diet plus commercial HA at 500 mg/kg body weight/day for 56 days. Every two weeks, lambs underwent hematological, biochemical, parasitological, immunological, fecal consistency, and performance analyses. After the experimental period, 10 lambs per group were slaughtered. Histological analyses included measuring abomasal mucosa thickness and mucus production in the abomasum, duodenum, jejunum, and ileum. Tissues from the abomasum, duodenum, jejunum, ileum, and cecum were also used for leukocyte counts and scanning electron microscopy (SEM) evaluations, while parasitological analysis consisted of parasite recovery from the abomasum and small intestine. The TG exhibited improved fecal consistency, a decrease in CD8 lymphocytes in the abomasum and duodenum, and reduced platelet counts. In general, hematological, biochemical, parasitological, histological, and performance parameters did not differ significantly between groups. HA fragments were not able to be distinguished with SEM on gastrointestinal mucosa surface. Overall, HA supplementation positively impacted digestive health by mitigating gastrointestinal inflammation.

Newcastle disease (ND) is a highly contagious disease with the potential to cause massive losses in the global poultry industry. This study evaluated the efficacy of three commercial live ND vaccines based on genotypes I and II (enterotropic) on mortality and viral shedding in specific pathogen-free (SPF) chickens challenged with circulating virulent Newcastle disease virus (vNDV) of genotype VII. Forty one-day-old SPF chickens were randomly divided into four experimental groups (n = 10) and vaccinated (one dose ≥ 10⁶ EID50) with one of three enterotropic ND vaccines (E1, E2, or E3) or received phosphate-buffered saline (PBS) as the control on the 8th day of age. At 28 days of age, the chicks were intramuscularly challenged with genotype VII (GVII) vNDV. Blood samples were collected before the challenge (at 28 days of age) and at 7 and 14 days post-challenge (dpc) to measure serum antibody titers against NDV using the hemagglutination inhibition (HI) test. Cloacal and oropharyngeal swabs were taken on the 3rd, 5th, 7th, and 10th dpc to evaluate viral shedding. The vaccinated groups showed significantly higher antibody titers and protection rates compared with controls (P < 0.05). At 28 days of age, the E2 group had a higher antibody titer compared to E3 (P < 0.05); however, no significant difference was noted between the vaccinated groups at 35 and 42 days of age. All vaccinated chickens showed significantly higher protection in the challenge test compared to the control group; where the E2 group acknowledges the complete protection (70%, 100%, 60%, and 0% for E1, E2, E3, and control, respectively). The E2 group also had the lowest number of shedder birds compared to the E1 and E3 groups (0% vs. 30% and 40%, respectively; P < 0.05). This study shows that some commercially mismatched enterotropic ND vaccines not only provide high levels of protection against genotype VII of vNDV but also effectively control viral shedding in infected chickens.