Effects of source of gossypol and supplemental iron on plasma gossypol in Holstein steers

Effects of over-load iron on nutrient digestibility, haemato-biochemistry, rumen fermentation and bacterial communities in sheep

There is a risk of iron overload in grazing livestock. However, the effects on nutrient absorption and rumen function induced by excessive iron have not been well understood. Therefore, the purpose of present study was to investigate the impact of over-load iron on growth performance, nutrient digestibility, blood biochemistry, rumen fermentation and bacterial communities in sheep. Twenty-four German Mutton Merino cross-bred sheep with weight (42.66 ± 2.34 kg BW) were randomly divided into 4 groups, each with 6 replicates and 1 sheep per replicate. The basal diet consisted of 60% Leymus chinensis hay and 40% concentrate. The sheep in 4 groups were fed the basal diets supplemented with 50 (Control), 500 (T1), 1,000 (T2) and 1,500 (T3) mg Fe/kg as ferrous sulphate monohydrate (FeSO₄ ·H₂ O) respectively. And the actual contents of iron in the diet were determined to be 457.68 (control), 816.42 (T1), 1,256.78 (T2) and 1,725.63 (T3) mg/kg respectively. The experiment lasted 62 days including a 7-day metabolism trial. During the whole experiment, the digestibility of dry matter, organic matter, neutral detergent fibre and acid detergent fibre showed a quadratic increase with increasing over-load iron levels (p < .05), and maximum responses were found with 500 mg/kg supplementation. However, the response of total VFA concentration showed a quadratic decrease, as did the concentrations of propionate, butyrate and valerate (p < .05). Serum total iron-binding capacity on day 30 showed a quadratic decrease with the increase in high-dose iron, while the serum iron content increased linearly at day 60 (p < .05). Excessive iron resulted in the change in bacterial communities. An increase in over-load iron linearly decreased the abundance of bacteria in the phylum Bacteroidetes (p < .05), but linearly increased the Firmicutes (p = .037) and Proteobacteria (p = .018). In addition, there was a quadratic effect (p = .003) on the Fibrobacteres, which was higher in the 500 and 1,000 mg/kg Fe-supplemented groups. At the genus level, there were quadratic effects on the abundances of Selenomonas_1 (p = .023) and Ruminococcaceae_UCG-014 (p = .016). Furthermore, feeding of iron linearly increased the relative abundances of Succiniclasticum and Succinivibrionaceae_UCG-002 (p < .05). These results indicate that increasing ferrous sulphate monohydrate in diets had no negative impact on the growth performance, but it changed nutrient digestibility, blood iron parameters, rumen fermentation and bacterial communities in sheep.

Pharmacokinetic comparison of gossypol isomers in cattle: transfer from diet to plasma and degradation by rumen microbes*#

A pharmacokinetic comparison of gossypol isomers in cattle was made by investigating their transfer from ingested food to plasma and their degradation by rumen microbes. The gossypol isomers in whole cottonseed, plasma, and rumen fluid were determined by high-performance liquid chromatography (HPLC). The intakes of (+)-and (−)-gossypol by cows on three farms were about 5.6–8.5 and 3.8–5.9 g/(d·herd), respectively. The plasma gossypol concentrations increased as ingestion increased and ranged from 0.31 to 0.48 μg/ml for the (+) form and from 0.39 to 0.59 μg/ml for the (−) form. The (+) form was slightly predominant (58.8%–59.8%) in the gossypol ingested by the cows, whereas the (−) form predominated (54.6%–55.9%) in the plasma. An in vitro study showed that at 6 h, 67.4% and 85.7% of the (−)-gossypol were degraded in 500 and 1000 μg/g treatment groups, respectively, and these increased to 83.6% and 92.5%, respectively, at 12 h. The regularity of the degradation of (+)-gossypol was similar to that of (−)-gossypol. These results showed that (−)-gossypol may be more persistent than (+)-gossypol in plasma, and that the degradation of the gossypol isomers in the rumen is rapid and not enantioselective in cattle.

Development of an RP-UHPLC-PDA method for quantification of free gossypol in cottonseed cake and fungal-treated cottonseed cake

Cottonseed cake biomass, which is a residue of oil extraction, is potentially appropriate for use as animal feed, given the high mineral, fibre and protein content. The presence of free gossypol, however, a toxic pigment in the glands of the cotton plant, limits use of this biomass for monogastric livestock. A promising method to detoxify cottonseed cake relies on fermentation by fungi, which can eliminate up to 100% of gossypol. In order to quantify trace levels of free gossypol in different cotton materials, including cottonseed cake treated with macrofungi, a simple and rapid chromatographic detection method was developed and validated. Under optimized conditions, extraction was performed using 70% acetone. The extract was then analysed by Ultra High-Performance Liquid Chromatography (UHPLC), with gradient elution on a C18 reverse phase column KINETEX^® (100 x 2.10 mm, 2.6 μm). Methanol-0.1% TFA aqueous solution was employed as mobile phase and PDA detection conducted at 254 nm. The optimized method was validated by analysis of specificity, linearity and range, limit of detection, limit of quantification, precision and accuracy. Detection and quantification limits were observed at 0.2 and 0.5 μg/mL, respectively. With good reproducibility, with precision (RSD)<10% and recovery greater than 94%, the developed assay was appropriate for quantification of low quantities of free gossypol. The validated method was successfully applied to determine trace levels of free gossypol cottonseed treated with a macrofungus.

Presence of free gossypol in whole cottonseed

The European Commission asked EFSA to assess information provided by the Spanish Ministry of Agriculture, Food and Environment, on the toxicity of free gossypol in relation to the use of whole cotton seed in feed for ruminants, in particular dairy cows, and, if necessary, to update the previous opinion of the EFSA Panel on Contaminants in the Food Chain (CONTAM) on gossypol as an undesirable substance in animal feed. Gossypol is a polyphenolic compound that exists in a racemic mixture of (+)‐gossypol and (‐)‐gossypol isomers. It occurs in free or (protein‐) bound forms in cottonseeds. The most commonly used cottonseeds in feed are from Upland and Pima varieties. The Pima variety is considered more toxic due to a higher content of the (‐)‐gossypol isomer. Upland whole cottonseeds (WCS) are fed with no further processing (after delinting); Pima varieties normally undergo further processing (grinding or cracking). It is claimed that WCS have a greater retention time in the rumen, which results in an increased detoxifying activity, compared to a shorter ruminal retention time, in the case of cracked cottonseed or cottonseed meal products. Increased erythrocyte fragility has been observed in cows given WCS Upland varieties at similar exposure levels as those resulting from an inclusion rate of 10% of WCS containing gossypol at 7,000 mg/kg in feed – the maximum permitted level of gossypol in WCS suggested by the Spanish Delegation. The information from the Spanish delegation does not differentiate between varieties in their suggestion for an increase in the maximum permitted content of free gossypol for WCS. As both Upland and Pima varieties are grown in the EU and are used for animal feed, both varieties of WCS should be considered. The CONTAM Panel considered it not necessary to update the previous opinion.

Replacing soybean meal for cottonseed meal on performance of lactating dairy cows

Cottonseed meal (CSM) is an alternative source of protein, and previous studies have been shown that it can replace soybean meal (SBM) without decrease animal performance. However, Brazilian CSM has a different chemical composition compared with the usual CSM reported in the literature. The objective of this experiment was to evaluate the effects of replacing SBM for Brazilian CSM on performance and energy balance of mid-lactating dairy cows. Forty-two Holstein cows were used in a replicate 3 × 3 Latin square design. Increasing contents of CSM (0, 15, and 30% of dry matter (DM)) were fed in diets to replace SBM. Milk yield and feed efficiency were linearly reduced with the replacement of CSM for SBM (P = 0.001). Milk fat content tended to increase quadratically (P = 0.07) with CSM addition. Replacing SBM for CSM affected milk protein content quadratically (P = 0.05). Milk urea nitrogen and plasma urea nitrogen (PUN) tended to respond quadratically (P = 0.06 and 0.10) when CSM replaced SBM to the diets. Variation in body weight (BW) also responded quadratically as CSM replaced SBM (P = 0.05). Altogether, the findings suggest better performance when cows receive SBM diet compared with the Brazilian CSM diet.

BNIP3 regulates AT101 [(-)-gossypol] induced death in malignant peripheral nerve sheath tumor cells

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive Schwann cell-derived sarcomas and are the leading cause of mortality in patients with neurofibromatosis type 1 (NF1). Current treatment modalities have been largely ineffective, resulting in a high rate of MPNST recurrence and poor five-year patient survival. This necessitates the exploration of alternative chemotherapeutic options for MPNST patients. This study sought to assess the cytotoxic effect of the BH3-mimetic AT101 [(-)-gossypol] on MPNST cells in vitro and to identify key regulators of AT101-induced MPNST cell death. We found that AT101 caused caspase-independent, non-apoptotic MPNST cell death, which was accompanied by autophagy and was mediated through HIF-1α induced expression of the atypical BH3-only protein BNIP3. These effects were mediated by intracellular iron chelation, a previously unreported mechanism of AT101 cytotoxicity.