Performance and immunity of heat-stressed broilers fed vitamin- and electrolyte-supplemented drinking water.

The efficacy of different vitamin and electrolyte treatments of drinking water for heat-stressed broilers was studied in two experiments. In Experiment 1, commercial broilers (50% male, 50% female, sexed), were subjected to four drinking water treatments: 1) unsupplemented water (control); 2) B-vitamins plus electrolytes (B+El); 3) vitamins A, D, and E, B-vitamins plus electrolytes (ADEB+El); and 4) vitamins A, D, and E and B-vitamins (ADEB). Each treatment group was replicated in eight pens containing 70 birds. All birds were provided ad libitum access to feed through to 43 days of age and subjected to the water treatment from 16 to 21 days and 38 to 43 days. The birds were exposed to the 35 C ambient temperature during the last 72 h of each period. Immune function was tested on the males in each pen while they received the water treatments from 24 to 34 days of age. In comparison with the control, feed conversion was improved 5.6% by ADEB+El and ADEB, and body weight gain was improved 6.7% by ADEB (P<.05). Total and IgG antibody response against SRBC after primary immunization was improved by B+El; whereas, B+El and ADEB treatments improved IgG after secondary immunization. The highest numbers of Sephadex-elicited peritoneal macrophages were found among ADEB-treated birds, but neither adherence nor phagocytic ability of macrophages from either group was affected. Natural killer cells from all except ADEB+El-treated birds exhibited comparably high tumoricidal activity. In Experiment 2, commercial male broilers were given either unsupplemented water or vitamin-supplemented water (ADEB treatment) at 22 to 30 days, 37 to 41 days, and 52 to 55 days. The birds were exposed to 35 C at 38 to 41 days and 53 to 55 days of age. The two water treatments were replicated in 16 pens of 40 birds. Vitamin treatment increased 1- to 63-day body weight gain and feed conversion by 3 and 5%, respectively (P<.1), and it reduced mortality related to heat stress by 63% (P<.05). Vitamin supplementation of drinking water is beneficial for heat-stressed broilers, but the benefit of electrolytes is questionable.