Journal of animal science最新文献

This study aimed to characterize trace mineral and vitamin A metabolism and redistribution during clinical and subclinical respiratory infection in beef on dairy crossbred steers (n = 29; BW = 230 ± 2.14 kg). Steers were assigned to one of four groups encompassing days -6 to -1, 0 to 5, 5 to 10, and 10 to 15 of an experimental viral-bacterial respiratory challenge. Steers were adapted to metabolism crates for 5 d prior to a 5-d total urine and fecal collection period and necropsied at the end of the period. On day 0, steers were inoculated with bovine respiratory syncytial virus strain 375 followed by an intratracheal inoculation with Mannheimia haemolytica strain D153 on day 7. A natural disease challenge occurred during the study, leading to all steers showing signs of disease at necropsy. Lung pathology scores, plasma Fe concentrations, and rectal temperatures for 5 d prior to necropsy were used to categorize animals into clinical (n = 9) and subclinical (n = 20) disease. These categories were confirmed by decreases in dry matter intake (P = 0.06) and nitrogen retention (P = 0.06) in animals with clinical disease compared to subclinical. Plasma concentrations of Zn and retinol were lesser in clinical disease (P ≤ 0.005). Conversely, liver (P = 0.02) and kidney (P = 0.06) concentrations of Zn were higher in clinical disease. This tissue sequestration occurred despite no difference in apparent Zn absorption or retention (P ≥ 0.69), providing evidence of systemic mineral redistribution. There was also no difference in the apparent absorption of Cu, Fe, and Mn (P ≥ 0.44), despite some differences in tissue concentrations. At the site of infection, expression of genes regulating vitamin A transport and metabolism (STRA6, RXRα, RBP4) increased (P ≤ 0.002) in non-lesion lung relative to diseased lung. In both lesion and non-lesion lung, clinical disease decreased RALDH2 expression relative to subclinical disease (P = 0.05). These findings demonstrate that BRD induces a coordinated redistribution of trace minerals from circulation to key tissues and alters local vitamin A metabolism in the lung. This highlights that plasma micronutrient concentrations during infection are not reflective of total body status, but rather an organized physiological response that prioritizes tissue-level demands.

Immune system stimulation (ISS) alters the metabolic demand for amino acids (AA), and amino acid-based nutritional strategies may mitigate performance reduction in pigs subjected to sanitary challenge conditions. This study aimed to evaluate the effect of extra supplementation of a combination of functional AA (FAA, +20% threonine, methionine, and tryptophan) preventively (pre-ISS), curatively (during-ISS) or both on the performance of growing pigs challenged with Salmonella Typhimurium (ST) and poor housing conditions. Fifty-two entire male pigs (21.7 ± 4.6 kg) were allocated to four dietary treatments, with a control AA profile diet fed throughout the experimental period (Control; NRC, 2012) or a FAA supplemented diet (FAA+; supplied +20% Trp: Lys, Thr: Lys, and Met+Cys: Lys above Control) fed only before the ISS (FAA Preventive), during the ISS (FAA Curative), or before and during the ISS-period (FAA Continuous). On day 0, after a 7-day pre-ISS-period (day -7 to -1, pre-ISS), all pigs were inoculated with ST (2 × 109 CFU/mL). Additionally, manure from a commercial pig farm was spread on the solid concrete floor, and the room was not cleaned during the ISS-period for 4 weeks (0 to 28 days). Thereafter, all pigs received the same standard diet for 9 weeks (days 29 to 91), and the facilities were cleaned daily. Pigs were group-housed and fed using five electronic precision feeders during pre-ISS and ISS-period (-7 to 28 days). There was no effect of providing additional FAA before the ISS-period on growth performance (P > 0.10), indicating that the control diet met at least the requirements under non-challenged conditions. Rectal temperature increased by 1.25 °C on day 1 of the ISS-period (P < 0.05) and remained higher than pre-ISS during days 2 to 7 of the ISS-period (P < 0.05). Control group had higher rectal temperature than the FAA Preventive (P < 0.05). Serum haptoglobin was higher on day 7 and 28 (P < 0.05), while albumin was lower on day 28 (P < 0.05), with lower concentrations in the control group compared with the FAA curative (P < 0.05). Higher final BW (P < 0.05), ADG (P < 0.05), and G: F (P < 0.05) were observed in the FAA Continuous compared to the Control. On day 28, FAA curative pigs showed higher total body protein content than FAA preventive pigs (P < 0.10). Nitrogen utilization efficiency improved by 32.6% (P < 0.05) for the FAA Curative compared with the Control. There were no remaining effects of treatments on BW or body composition on day 91 (P > 0.10). In conclusion, the combination of short-term preventive and curative strategies with FAA dietary supplementation modulated the immune response and improved the growth performance of growing pigs under chronic immune system stimulation.