Effect of humic acid supplementation on lamb gastrointestinal health and performance

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.