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Abstract
Three studies were conducted to determine the effect of nutritional factors on performance, bone mineralization, leg abnormalities, and Ca metabolism in broilers from 1 day to 3 wk of age. Two sulfate sources (potassium sulfate (K$\sb2$SO$\sb4$) and copper sulfate (CuSO$\sb4$)), and different levels of sulfate (.024,.034, and.044%), Ca (.6 and 1.0%), protein (CP (18 and 22%)), and sulfur amino acids (SAA (.93, 1.23, and 1.53%)) were used in the first study. As sulfate level increased, tibia ash increased in birds fed CuSO$\sb4$, and decreased in birds fed K$\sb2$SO$\sb4$ ($P<.024$). Tibia Ca retention (TCR) decreased linearly with sulfate level ($P<.05$) in birds fed.6% Ca. Excess SAA (1.53%) and 18% CP significantly reduced performance. Fecal Ca excretion decreased ($P<.01$) as the SAA level was increased. Bone mineralization was not significantly affected by excess SAA.
In the second study, involving three experiments, two Ca levels (.6 and 1.0%), and four (potassium) sulfate levels (0,.1,.2%, and.4%) were used. Urine and feces were collected separately in Experiments 2 and 3. Birds were dosed with $\sp{45}$Ca in Experiment 3. Sulfate increased BW gain linearly in birds fed 1.0% Ca but not when fed.6% Ca (Experiment 1). Plasma $\sp{45}$Ca and blood pH increased significantly with sulfate level; however,blood pCO$\sb2$, HCO$\sb3\sp-$, and base excess were not affected ($P>.05$). Urinary Ca, or $\sp{45}$Ca, and fecal Ca increased significantly with sulfate level. Inorganic (potassium) sulfate did not impair bone mineralization.
In the third study, four experiments were conducted. Three levels of available P (.3,.5, and.7%), and Cl (.2,.3, and.4%); and three levels of Ca (.6, 1.0, and 1.6%) and Mg (.06,.16, and.24%) were used in Experiments 1 and 2, respectively. The milliequivalents of cations (Ca$\sp{++}$, Mg$\sp{++}$, Na$\sp+$, and K$\sp+$) and anions (Cl$\sp-$, P$\sp-$, and S$\sp-$) per kg of diet were expressed as cation:anion ratio (CAR). Lowering CAR in Experiments 1 and 3, significantly increased BW gain, tibia ash and Ca, ash weight, and urinary $\sp{45}$Ca; and decreased severity of crooked tibia, plasma $\sp{45}$Ca and $\sp{45}$Ca retention in tibia. Reducing CAR in Experiment 2, significantly decreased gain:feed, tibia ash and Ca, tibia weight, ash weight, and severity of crooked tibia; and increased the severity of TD. Urinary $\sp{45}$Ca was closely related to low pH in the urine. Response variables were more dependent on the level of individual electrolytes than to CAR.
