Effect of adding a mycotoxin-sequestering agent on milk aflatoxin M₁ concentration and the performance and immune response of dairy cattle fed an aflatoxin B₁-contaminated diet

This project aimed to examine the effects of adding 2 doses of a montmorillonite-based mycotoxin adsorbent on milk aflatoxin M(1) (AFM(1)) concentrations and the performance and innate immune response of dairy cows fed an aflatoxin B(1) (AFB(1))-contaminated diet. Eight lactating cows were used in a duplicated 4×4 Latin square design with 12-d periods. Treatments included the following: (1) control diet (C), (2) aflatoxin diet (T) containing C and 75 µg of AFB(1)/kg, 3) low-clay (LC) diet containing T and Calibrin A (Amlan International, Chicago, IL) added at 0.2% of the diet dry matter (DM), and 4) high-clay diet (HC) containing T and Calibrin A added at 1% of the diet DM. Milk production and DM intake were recorded daily and milk was sampled twice daily on d 5, 9, 10, 11, and 12 in each period. Blood samples were collected on d 5 and 9 of each period. Dietary treatments did not affect DM intake, milk yield, or feed efficiency. Even though cows were limit fed, feeding T instead of C reduced milk fat yield (0.67 vs. 0.74 kg/d) and milk protein concentration (3.28 vs. 3.36%). Concentrations of AFM(1) in milk of cows fed the T and LC diets were similar (0.57 and 0.64 µg/kg) and greater than those of cows fed the HC diet (0.46 µg/kg). Haptoglobin concentration was greater (22.0 vs. 14.4) and β(2)-integrin expression (220 vs. 131) tended to be greater in cows fed diet T instead of C, but values for cows fed LC, HC, and C did not differ. In comparison to C, feeding T increased the innate immune response and decreased milk fat yield and milk protein concentration, but feeding LC and HC did not affect these measures. Only the HC diet reduced milk AFM(1) concentration.

Effects of duodenal infusion of free α-linolenic acid on the plasma and milk proteome of lactating dairy cows

This study is an exploratory analysis for understanding the effect of a duodenal infusion of an α-linolenic acid (LNA) on the plasma and milk proteome of lactating dairy cows. Four primiparous Holstein cows were fitted with duodenal cannulas and received 0, 100, 200, 300 and 400 g/day of LNA in a two-treatment crossover design. Blood and milk were collected for determination of protein composition by two-dimensional gel electrophoresis. Alteration of protein spots was detected and identified using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF-TOF MS). Plasma haptoglobin levels, and milk β-casein A2, αs1-casein variant and albumin, did not differ in cows after infusion of 0, 100, 200 and 300 g/day of LNA, but were increased after the cows received duodenal infusion of 400 g/day of LNA. Western blot analysis of haptoglobin expression in plasma confirmed the alterations in protein expression seen using MS. This study demonstrated that infusion of high doses of LNA by duodenal cannula can result in metabolic stress within the bovine intestine and in changes in milk composition.