Effect of hydroxyselenomethionine on lactation performance, blood profiles, and transfer efficiency in early-lactating dairy cows

The current study investigated the effects of hydroxyselenomethionine (HMBSe), a novel organic selenium (Se) additive, on lactation performance, blood profiles, antioxidative status, and transfer efficiency of Se in early-lactation dairy cows. Sixty multiparous early-lactating dairy cows with similar days in milk (57 d; standard deviation = 9.9) and milk yield (36.5 kg/d; standard deviation = 1.42) were fed a basal diet containing 0.04 mg of Se/kg (dry matter basis). These cows were assigned to 1 of 4 groups following a randomized complete block design as follows: control (basal diet) or HMBSe addition (0.1, 0.3, or 0.5 mg of Se/kg of dry matter). The experiment lasted for 13 wk, with the first week as adaptation. The results showed that milk yields (raw, protein, and lactose) and feed efficiency were improved in a quadratic manner following increased dietary HMBSe addition, whereas energy-corrected milk, 4% fat-corrected milk, and total solid yields tended to be enhanced quadratically. In terms of whole-blood variables, red blood cell and white blood cell levels were increased quadratically, whereas hemoglobin concentration increased linearly with increased HMBSe addition. Plasma nonesterified fatty acid concentrations tended to increase linearly along with HMBSe addition. Plasma superoxide dismutase activity increased quadratically with increased HMBSe addition. The total antioxidant capacity in plasma tended to improve quadratically when cows were fed more HMBSe. Moreover, plasma malondialdehyde concentrations of dairy cows tended to decrease in a quadratic manner when dietary HMBSe increased. The Se concentrations in milk, plasma, and milk/plasma ratio increased linearly following increased HMBSe addition. In conclusion, HMBSe improved lactation performance, health status, and milk Se concentrations in early-lactating dairy cows.

Type I and type II cytokine production of CD4+ T-cells in immune response biased dairy cattle around calving

The peripartum period is a period of high stress, transition and management changes for dairy cows. It is associated with higher incidence of both metabolic and pathogenic disease. Both antibody-(AMIR) and cell-(CMIR) mediated immune responses play a key role in the maintenance of health in mammals protecting against extracellular and intracellular pathogens, respectively. Generally, interferon gamma (IFN-γ) has been associated with CMIR, whereas interleukin 4 (IL-4) has been associated with AMIR bias, and interleukin 17 (IL-17A) is associated with pro-inflammatory. It has been previously demonstrated that cows can be classified as high (H), average (A), and low (L) immune responders based upon their AMIR and CMIR to test antigens, and that this classification is associated with disease occurrence throughout lactation. The mechanisms behind these differences in phenotype and the effects of the peripartum period have not been fully investigated. The aim of this study was to determine the effects of the peripartum period on cytokine production of CD4+ T-cells or T helper (Th) cells, key mediators of the adaptive immune response. Immune response phenotyped cows were selected based on H-AMIR/L-CMIR (H-AMIR cows; n = 10) and H-CMIR/L-AMIR (H-CMIR cows; n = 11) response to test antigens. Isolated CD4+ T-cells collected at 28 days before calving (prepartum samples), 4 days after calving (early postpartum samples), and 21 days after calving (late postpartum samples) from these groups were stimulated with Concanavalin-A (ConA) with unstimulated controls. Subsequently, IL-4, IFN-γ, and IL-17A concentrations were quantified by ELISA. Overall, there was no obvious decline in IL-4, IFN-γ or IL-17A close to calving observed from CD4+ T-cells from each of these phenotypically distinct groups of cows. However, CD4+ T-cells isolated from H-CMIR secreted higher amounts of IL-4 (746.43 ± 428 pg/mL), IL-17A (446IL ± 62 pg/mL), and IFN-γ (7755.79 ± 4449 pg/mL) than H-AMIR cows (IL-4 (212.15 ± 121 pg/mL), IL-17A (163.15 ± 87 pg/mL), and IFN-γ (2909.771 ± 1671 pg/mL)) on day 21 after calving, late postpartum. This study indicates a genetic predisposition based on immune response phenotype of cytokine production from CD4+ T-cells around calving.