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Two experiments were conducted on sheep to determine the effect of dietary supplementation with zinc and a medicinal plant mixture on haematological parameters and microbial activity in the rumen and large intestine. In Experiment 1, 24 male lambs were randomly divided into four groups: One group was fed an unsupplemented basal diet (control), and three groups were fed a diet supplemented with 70 mg Zn/kg diet in the form of Zn sulphate (ZnSO ), a Zn-chelate of glycine hydrate (Zn-Gly) or a Zn-proteinate (Zn-Pro), for five months. The ruminal content was collected separately from each lamb, and batch cultures of ruminal fluid were incubated in vitro with mixture of medicinal plants (Mix) with different roughage:concentrate ratios (800:200 and 400:600, w/w). Bioactive compounds in Mix were quantified by UPLC/MS/MS. In Experiment 2, four sheep were fed a diet consisting of meadow hay and barley grain (400:600, w/w), with Zn-Gly (70 mg Zn/kg diet), Mix (10% replacement of meadow hay) or Zn-Gly and Mix (Zn-Gly-Mix) as supplements in a Latin square design. Mix decreased total gas (p < 0.001) and methane (p < 0.01) production in vitro. In Experiment 1, caecal isobutyrate and isovalerate concentrations varied among the dietary treatments (p < 0.01). The isovalerate concentration of the zinc-supplemented groups in the distal colon was higher (p < 0.001) compared with the control. In Experiment 2, the molar proportion of isobutyrate was the highest in the faeces of the sheep fed the diet with Zn-Gly-Mix (p < 0.01). The plasma zinc concentration was higher in the groups fed a diet supplemented with zinc (p < 0.001). The haematological profile and antioxidant status did not differ between the dietary groups (p > 0.05). The diets containing medicinal plants and organic zinc thus helped to modulate the characteristics of fermentation in ruminants.

The study investigated the effect of dietary zinc glycine chelate and potato fibre on the absorption and utilisation of Zn, Cu, Fe, and Mn; the activity of Zn-containing enzymes (superoxide dismutase, SOD; alkaline phosphatase, ALP); and zinc transporter concentrations (metalothionein1, MT1; zinc transporter1, ZnT1) in tissues, with a special emphasis on the small intestine. Twenty-four barrows (Danbred × Duroc) were randomly allotted to four diets (supplemented with 10 g/kg of crude fibre and 120 mg Zn/kg) that consisted of cellulose and either zinc sulphate (C) or zinc glycinate (ZnGly), or contained potato fibre supplemented with ZnSO4 (PF) or ZnGly (PF + ZnGly). Feeding PF can influence the Zn absorption in the small intestine due to reduced zinc transporters MT1 and ZnT1 in the jejunum. The activity of antioxidant enzyme SOD and liver ZnT1, and duodenal iron concentrations were increased in the PF treatments. Dietary ZnGly did not significantly influence the Zn distribution, but it may alter the absorption of Fe and Mn. Given the elevated content of thiol groups and the Zn/Cu ratio in plasma, as well as the altered SOD activity and MT content in the tissues, we can conclude that feeding PF and ZnGly can influence the mineral and antioxidant status of growing piglets. However, further research is needed in order to elucidate the effect of both dietary sources on the transport systems of other minerals in enterocytes.

Background Lactating dairy cows are the greatest livestock contributor of methane, a major global greenhouse gas (GHG). However, good feeding management with adequate mineral intake can offers an effective approach to maintaining high levels of milk production and the health of dairy cows over the entire course of lactation, while also helping to reduce methane emission. The study described here investigated the plasma concentrations of both macroelements (Ca, Na, K, Mg, P) and microelements (Zn, Cu, Fe, Mn), as well as enteric methane emission and milk composition in high-yielding dairy cows in different lactation periods. The experiment was performed on Holstein–Friesian dairy cows with the average milk yield of 41 (± 9) L/day in a Polish commercial farm with modern dairy systems. A total of thirty high-yielding dairy cows were randomly assigned into three groups differing by lactation stage: early stage (Early, days 25–100), middle stage (Middle, days 101–250), and late stage (Late, day 250 and later). Dietary treatment for all cows was a total mixture ration (TMR) with maize and alfalfa silage the main forage components. Results The greatest milk yield and methane production were recorded in early-stage lactating cows, but the greatest methane intensity per kg of corrected milk was recorded in the late stage of lactation. Plasma concentrations of macroelements and microelements did not differ by lactation stages, but increased plasma concentrations of Zn and Fe and decreased plasma levels of Mg were noted during lactation. A positive correlation was found between plasma levels of Mg and other macroelements (Ca, Na, K), and between the concentrations of Fe and Zn, P in plasma, but no correlation between methane emission and mineral status was detected in the different lactation stages. Conclusions Our results showed different mineral requirements and enteric methane emissions in each lactation stage. The feeding strategy and mineral utilization were adequate to maintain the health, mineral status, and milk production of the Holstein cows during the entire lactation period, and suggest an effective way of reducing methane emission.

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