Combined Effect of Age and Ambient Temperature on the Comparative Growth of Broiler Chicks Fed Tallow and Soybean Oil

Performance of battery-reared broiler chicks fed diets containing either tallow or soybean oil from 1 to 28 days of age was compared in experiments carried out in summer and winter (temperatures 17 to 35 and 6 to 21 C, respectively). In two experiments carried out in the summer, weight gain of chicks fed experimental diets during 1 to 14 or 7 to 21 days of age was not affected by dietary fat source at concentrations of 4.8 and 3.5%, respectively. However, extending the experimental period for 1 week resulted in a significant (P<.05) reduction in weight gain of chicks fed the tallow-supplemented diet. Feed intake was not affected by dietary fat source. In the experiment performed in the winter, body weight of chicks fed a diet containing 4.8% tallow during 1 to 10 days of age was significantly depressed, whereas feed intake was not affected by fat source. Weight gain during the period 11 to 28 days, however, was not affected by dietary fat, but feed intake was significantly higher in chicks fed the tallow-supplemented diet. It is concluded that the response of chicks to dietary fats differing in their degree of saturation, measured in terms of feed intake and weight gain, is dependent on the combined effect of age and ambient temperature.