Utilization of Yolk as a Feed Source In newly Hatched Chicks With and Without vitellin
Increasing feed efficiency and early body weight gain has always been a top priority in the poultry industry. This experiment was designed to study the effects of feed sources differing in energy and protein levels as well as yolk removal on behavior, feed efficiency, energy intake, body weight and GIT growth in newly hatched chicks. Chicks in Experiment 1, Trial 1, were White Plymouth Rock chicks from the 40th generation of a line selected for high body weight, fed either freeze dried unincubated yolk (Diet Y) or mash (Diet M-A) from day 0 to day 5, after which all chicks were fed Diet M-A. Chicks in Experiment 1, Trial 2 were males from a commercial layer stock fed either a choice of residual yolk (yolk harvested from newly hatched chicks) and unincubated yolk (Diet Y), or mash (Diet M-A) alone from day 0 to day 6, after which all chicks were fed Diet M-A. In these experiments where chicks were offered yolk as a feed source for a period of time, body weight gain was significantly reduced and mortality increased. There was evidence that Diet Y chicks, consuming a high-lipid feed, experienced decreased appetite. There were no differences in body weight between the two diet groups in Trial 1 or Trial 2 on day 0, but during the days in which yolk was fed, Diet M-A chicks maintained a weight advantage over Diet Y chicks. Chicks used in Experiment 2 were males from a commercial layer stock. Yolk sacs were surgically removed (Trt YR) from half of the chicks while the other half remained yolk-intact (Trt YI). From day 0 to day 6, all chicks were offered a choice of residual yolk (Diet Y) or mash (Diet M-A) and beginning on day 6, all chicks were fed Diet M-A. Throughout the experiment, the Trt YI chicks maintained their body weight advantage over the Trt YR chicks, but by day 13, the Trt YR chicks gained proportionately more body weight. Because of wastage, feed efficiency and energy intake values were not reported. The only difference in GIT data was the amount of chyme; its value was higher in the Trt YI chicks than in Trt YR chicks. Behavior results showed that Trt YI chicks stood more while Trt YR chicks rested more throughout the experiment. Chicks used in Experiment 3 were males from a commercial layer stock. This experiment consisted of 4 groups: Trt YI chicks fed Diet M-E (mash feed high in energy and protein), Trt YI chicks fed Diet M-A (mash feed lower in energy and protein), Trt YR chicks fed Diet M-E and Trt YR chicks fed Diet M-A. Serial dissections on days 6, 13 and 20 allowed for better understanding of effects of diet and/or treatment on the growth of selected parts of the GIT. On days 13 and 20, there were no differences due to diet or treatment for GIT data except for the consistent difference due to diet for relative weight of the gizzard, whose value was higher in the Diet M-A chicks. Similar to results from Experiment 2, on day 13, Trt YR chicks fed Diet M-A gained more body weight than the Trt YI chicks fed the same diet. Also consistent with Experiment 2, of chicks fed Diet M-A, the Trt YI chicks stood more than the Trt YR chicks. Due to unusually large feed consumption values, feed efficiency and energy intake data were not reported.
- Masters Theses