Dietary Cadmium Exposure in Black Goats: Impacts on Growth Performance, Serum Biochemical and Immune Parameters, Meat Quality, and Tissue Accumulation

Cadmium (Cd) present in soil can accumulate in plants and subsequently affect the safety and quality of animal-derived food products. This study investigated the effects of dietary Cd exposure derived from rice straw on the growth performance, serum biochemical and immune parameters, meat quality, and tissue accumulation of black goats. A 90-day feeding trial was carried out with 42 healthy male black goats at 4 months. Prior to the feeding trial, six goats were slaughtered to establish baseline group, and the remaining 36 goats were randomly assigned to two groups fed with a diet containing Cd-contaminated rice straw (CAD, n = 18) or not (CON, n = 18). At 30, 60, and 90 d, six goats per group (n = 6) were randomly selected and slaughtered for sample collection. The results showed that dietary Cd exposure had no significant effects on growth performance and the indices of heart, liver, spleen, lung, and kidney (p > 0.05). Meanwhile, it induced tissue-specific and time-dependent Cd accumulation, with lymph nodes identified as the primary Cd target tissue in goats, followed by kidney and liver (p < 0.05). The CAD group exhibited higher concentrations of serum urea nitrogen and interleukin-10, and lower concentrations of serum glucose and creatinine. Fecal cadmium deposition efficiency (CdE) ranged from 95.68% to 97.01% in the CON group and from 68.48% to 88.74% in the CAD group, whereas the CdE in muscle and internal organs remained below 2% in both groups. These findings indicate that fecal excretion constitutes the predominant elimination pathway for ingested Cd, with only a negligible proportion retained in edible tissues and internal organs. However, based on the present findings, we cannot recommend the use of Cd-contaminated rice straw as a feed source for goats, nor can we confirm the safety of meat from exposed animals for human consumption. Further long-term studies, including human health risk assessments, are needed before any recommendations can be made.